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1.  Antimicrobial activity of the bioactive components of essential oils from Pakistani spices against Salmonella and other multi-drug resistant bacteria 
The main objective of this study was the phytochemical characterization of four indigenous essential oils obtained from spices and their antibacterial activities against the multidrug resistant clinical and soil isolates prevalent in Pakistan, and ATCC reference strains.
Chemical composition of essential oils from four Pakistani spices cumin (Cuminum cyminum), cinnamon (Cinnamomum verum), cardamom (Amomum subulatum) and clove (Syzygium aromaticum) were analyzed on GC/MS. Their antibacterial activities were investigated by minimum inhibitory concentration (MIC) and Thin-Layer Chromatography-Bioautographic (TLC-Bioautographic) assays against pathogenic strains Salmonella typhi (D1 Vi-positive), Salmonella typhi (G7 Vi-negative), Salmonella paratyphi A, Escherichia coli (SS1), Staphylococcus aureus, Pseudomonas fluorescens and Bacillus licheniformis (ATCC 14580). The data were statistically analyzed by using Analysis of Variance (ANOVA) and Least Significant Difference (LSD) method to find out significant relationship of essential oils biological activities at p <0.05.
Among all the tested essential oils, oil from the bark of C. verum showed best antibacterial activities against all selected bacterial strains in the MIC assay, especially with 2.9 mg/ml concentration against S. typhi G7 Vi-negative and P. fluorescens strains. TLC-bioautography confirmed the presence of biologically active anti-microbial components in all tested essential oils. P. fluorescens was found susceptible to C. verum essential oil while E. coli SS1 and S. aureus were resistant to C. verum and A. subulatum essential oils, respectively, as determined in bioautography assay. The GC/MS analysis revealed that essential oils of C. cyminum, C. verum, A. subulatum, and S. aromaticum contain 17.2% cuminaldehyde, 4.3% t-cinnamaldehyde, 5.2% eucalyptol and 0.73% eugenol, respectively.
Most of the essential oils included in this study possessed good antibacterial activities against selected multi drug resistant clinical and soil bacterial strains. Cinnamaldehyde was identified as the most active antimicrobial component present in the cinnamon essential oil which acted as a strong inhibitory agent in MIC assay against the tested bacteria. The results indicate that essential oils from Pakistani spices can be pursued against multidrug resistant bacteria.
PMCID: PMC3853939  PMID: 24119438
Essential oils; Multidrug resistant; Minimum inhibitory concentration; GC/MS; TLC-bioautography
2.  Detection of Antibodies to a Pathogenic Mycoplasma in American Alligators (Alligator mississippiensis), Broad-Nosed Caimans (Caiman latirostris), and Siamese Crocodiles (Crocodylus siamensis) 
Journal of Clinical Microbiology  2001;39(1):285-292.
An epidemic of pneumonia with fibrinous polyserositis and multifocal arthritis emerged in captive American alligators (Alligator mississippiensis) in Florida, United States, in 1995. Mycoplasma alligatoris sp. nov. was cultured from multiple organs, peripheral blood, synovial fluid, and cerebrospinal fluid of affected alligators. In a subsequent experimental inoculation study, the Henle-Koch-Evans postulates were fulfilled for M. alligatoris as the etiological agent of fatal mycoplasmosis of alligators. That finding was remarkable because mycoplasmal disease is rarely fatal in animals. An enzyme-linked immunosorbent assay (ELISA) for the detection of antibodies produced by alligators in response to M. alligatoris exposure was developed by using plasma obtained from naturally infected alligators during the original epidemic. The assay was validated by using plasma obtained during an experimental dose-response study and applied to analyze plasma obtained from captive and wild crocodilian species. The ELISA reliably detected alligator seroconversion (P < 0.05) beginning 6 weeks after inoculation. The ELISA also detected seroconversion (P < 0.05) in the relatively closely related broad-nosed caiman Caiman latirostris and the relatively distantly related Siamese crocodile Crocodylus siamensis following experimental inoculation with M. alligatoris. The ELISA may be used to monitor exposure to the lethal pathogen M. alligatoris among captive, repatriated, and wild crocodilian species.
PMCID: PMC87716  PMID: 11136785
3.  Antibacterial activity of aquatic gliding bacteria 
SpringerPlus  2016;5:116.
The study aimed to screen and isolate strains of freshwater aquatic gliding bacteria, and to investigate their antibacterial activity against seven common pathogenic bacteria. Submerged specimens were collected and isolated for aquatic gliding bacteria using four different isolation media (DW, MA, SAP2, and Vy/2). Gliding bacteria identification was performed by 16S rRNA gene sequencing and phylogenetic analysis. Crude extracts were obtained by methanol extraction. Antibacterial activity against seven pathogenic bacteria was examined by agar-well diffusion assay. Five strains of aquatic gliding bacteria including RPD001, RPD008, RPD018, RPD027 and RPD049 were isolated. Each submerged biofilm and plastic specimen provided two isolates of gliding bacteria, whereas plant debris gave only one isolate. Two strains of gliding bacteria were obtained from each DW and Vy/2 isolation medium, while one strain was obtained from the SAP2 medium. Gliding bacteria strains RPD001, RPD008 and RPD018 were identified as Flavobacterium anhuiense with 96, 82 and 96 % similarity, respectively. Strains RPD049 and RPD027 were identified as F. johnsoniae and Lysobacter brunescens, respectively, with similarity equal to 96 %. Only crude extract obtained from RPD001 inhibited growth of Listeria monocytogenes (MIC 150 µg/ml), Staphylococcus aureus (MIC 75 µg/ml) and Vibrio cholerae (MIC 300 µg/ml), but showed weak inhibitory effect on Salmonella typhimurium (MIC > 300 µg/ml). Gliding bacterium strain RPD008 should be considered to a novel genus separate from Flavobacterium due to its low similarity value. Crude extract produced by RPD001 showed potential for development as a broad antibiotic agent.
PMCID: PMC4742450  PMID: 26885469
Aquatic gliding bacteria; Antibacterial activity; Pathogenic bacteria; Isolation media; Agar-well diffusion assay; Biofilm; Novel genus
4.  Antibacterial, Antifungal, and Insecticidal Potentials of Oxalis corniculata and Its Isolated Compounds 
Oxalis corniculata is a common medicinal plant widely used against numerous infectious diseases. The agrochemical potential of methanolic extract, n-hexane, chloroform, ethyl acetate, and n-butanol fractions were assessed to measure the antibacterial, antifungal, and insecticidal activities of the plant. The crude, chloroform, and n-butanol soluble fractions showed excellent activities against Escherichia coli, Shigella dysenteriae, Salmonella typhi, and Bacillus subtilis but have no activity against Staphylococcus aureus. Similarly the crude, n-hexane, and chloroform fractions were also found to have significant activity against fungal strains including Fusarium solani, Aspergillus flexneri, and Aspergillus flavus and have no activity against Aspergillus niger. Chemical pesticides have shown very good results at the beginning, but with the passage of time the need was realized to use the natural plant sources for the safe control of insects. The current study will provide minor contribution towards it. High mortality rate was recorded for the crude extract and chloroform fraction against Tribolium castaneum. The two isolated compounds 5-hydroxy-6,7,8,4′-tetramethoxyflavone (1) and 5,7,4′-trihydroxy-6,8-dimethoxyflavone (2) were evaluated for antibacterial, antifungal, and insecticidal activities. The results showed that compound 2 was more active than compound 1 against the tested bacterial strains and insects.
PMCID: PMC4383515  PMID: 25873973
5.  Bio Prospecting of Marine-derived Streptomyces spectabilis VITJS10 and Exploring its Cytotoxicity Against Human Liver Cancer Cell Lines 
Pharmacognosy Magazine  2015;11(Suppl 3):S469-S473.
Recently, numerous pathogens have developed resistance due to the indiscriminate use of commercial therapeutic drugs.
The main aim of the study was to evaluate the bioactive potential of the Streptomyces spectabilis VITJS10 crude extract.
Materials and Methods:
The S. spectabilis VITJS10 ethyl acetate extract was tested for antibacterial, antioxidant, and cytotoxic properties. Genotypic characterization was done using 16S r-DNA partial gene amplification and sequencing. The authenticity of the crude chemical constitutes were determined by gas chromatography–mass spectrometry (GC-MS).
The antibacterial potential revealed the effective activity against Shigellaflexneri (MTCC No: 1457) (22 mm), Salmonella typhi (MTCC No: 1167) (23 mm), Escherichia coli (MTCC No: 1588) (22 mm), Pseudomonas aeruginosa (MTCC No: 4676) (22 mm) at 20 mg/mL concentration. Scavenging ability of the extract was determined using 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay revealing its 95% inhibition at 5 mg/mL concentration. Hepatocellular cancer cells (HepG2) cell line was used to evaluate the cytotoxicity by 3-(4, 5-dimethyl thiazol-2yl)-2, 5-diphenyl tetrazolium bromide assay. The extract showed maximum inhibition at IC50 of 250 μg/mL with 53.6% cell viability. The highest 16S rRNA gene sequence homogeneity was observed 99% similar with the novel strain S. spectabilis S3-1. The chemical components of the crude extract of VITJS10 were detected with 37 chemical constituents. However three major compounds were identified, namely Sulfurous acid, 2-ethylhexyl tridecyl ester, Phenol, 2,4-bis (1,1-dimethylethyl), and Trans-2-methyl-4-n-pentylthiane, S, S-Dioxide.
Hence the present study justifies the overwhelming circumstantial evidence as the most bioactive metabolites from the marine origin, which has potential utilization in pharmaceutical industry.
The aim of this study was to explore the bioactive potential of marine Streptomyces sp. isolated from marine soil and understand the bioactive properties of the crude extracts. It is clearly evident from the study that the bioactive metabolites produced by Streptomyces sp. exhibited good antibacterial, antioxidant and anticancer activity. Our results indicated that Starch casein medium was the good base for bioactive metabolite production. The taxonomic position of Streptomyces sp. isolated revealed unique pattern of phenotypic properties that distinguished it from representatives. The molecular characterization results provided valuable data for establishing the internal taxonomic structure of the genus. Hence high mortality rates, serious side effects, deficiencies of the available chemotherapeutics, and high costs during treatment clearly underscore the need to develop new anticancer agents, With the above significant features the strain could be recommended for its use in medicinal and agricultural sectors, an extensive knowledge on the behavior of natural compounds can be gained for the benefit of health.
PMCID: PMC4745219  PMID: 26929583
Bioactivity; cytotoxicity; MARINE actinomycetes; secondary metabolites; Streptomyces spectabilis; VITJS10
6.  Antimicrobial activity, toxicity and selectivity index of two biflavonoids and a flavone isolated from Podocarpus henkelii (Podocarpaceae) leaves 
Different parts of Podocarpus henkelii have been used in many cultures around the world to treat ailments such as cholera, stomach diseases, rheumatism, cancer, canine distemper in dogs and gall sickness in cattle. The aim of this study was to evaluate the biological activity and toxicity of isolated compounds from Podocarpus henkelii after an earlier study indicated a promising activity in crude extracts against viral pathogens of veterinary importance.
The antibacterial and antifungal activity of two biflavonoids 7, 4’, 7”, 4”’-tetramethoxy amentoflavone (TMA), isoginkgetin (IGG) and podocarpus flavone–A (PFA) isolated from the leaves of Podocarpus henkelii were determined using a serial microplate dilution method with tetrazolium violet as growth indicator. The cytotoxicity of compounds TMA and IGG were determined on different cell types using a tetrazolium-based colorimetric cellular assay (MTT). The Ames test was used to determine their mutagenic activities.
TMA had reasonable antifungal activity against Aspergillus fumigatus (MIC = 30 μg/ml). IGG had a wide spectrum of activity against four bacterial and two fungal pathogens with much higher selectivity index values obtained for A. fumigatus and Cryptococcus neoformans (SI > 30). PFA had a broad spectrum of activity against Enterococcus faecalis and Pseudomonas aeruginosa (SI > 15) and less activity against the two fungal pathogens. In both the cytotoxicity assays and Ames mutagenicity test using Salmonella typhimurium strains TA98 and TA100, TMA and IGG had no deleterious effect on the different cell types and did not induce mutations in the Ames test.
Although the antimicrobial activities of the isolated compounds were not that exciting, the compounds had no cytotoxic activity at the highest concentration (1000 μg/ml) tested against all three cell lines. IGG was the most active against E. coli, S. aureus, A. fumigatus and C. neoformans, exhibiting both antibacterial and antifungal activity with good selectivity index values. PFA had a broad spectrum of activity against E. faecalis and P. aeruginosa. The two compounds isolated had low toxicity and no genotoxic activity in the Ames test.
PMCID: PMC4197215  PMID: 25293523
Selectivity index; Biflavonoids; Antimicrobial activity; Cytotoxicity; Mutagenicity
7.  In Vitro Antibacterial, Antifungal, Antibiofilm, Antioxidant, and Anticancer Properties of Isosteviol Isolated from Endangered Medicinal Plant Pittosporum tetraspermum 
This study aimed to investigate the in vitro antibacterial, antifungal, antibiofilm, antioxidant, and anticancer properties of isosteviol isolated from endangered medicinal plant Pittosporum tetraspermum. Pure compound was obtained and characterized by column chromatography followed by 1H NMR, 13C NMR, IR, and mass spectral analysis. The antimicrobial activities of the compound were assessed by the broth microdilution method and the antioxidant properties were determined using reducing ability assay, DPPH scavenging assay, hydroxyl radical scavenging activity, and superoxide radical scavenging assay. Anticancer study was evaluated by following MTT assay. Column purification and spectrocopical analysis lead to identifying isosteviol from the crude ethyl acetate extract. The compound exhibited significant activity against bacteria such as Staphylococcus epidermidis (125 µg/mL), Staphylococcus aureus (125 µg/mL), and Klebsiella pneumoniae (62.5 µg/mL). The MIC of the compound against Candida albicans, Aspergillus niger, and Trichophyton mentagrophytes was 62.5, 125, and 500 µg/mL, respectively. The compound showed comparatively better antibiofilm activity against E. coli, S. typhi, and P. aeruginosa. Furthermore, it exhibited good antioxidant properties. Anticancer properties of the compound against Vero and MCF7 cell lines were its advantage. Novel isosteviol would be useful to reduce the infectious diseases caused by pathogenic microorganisms or slow the progress of various oxidative stress-related diseases.
PMCID: PMC4460244  PMID: 26101532
8.  A study of antimicrobial activity, acute toxicity and cytoprotective effect of a polyherbal extract in a rat ethanol-HCl gastric ulcer model 
BMC Research Notes  2012;5:546.
The decoction of the aerial parts of Rhynchosia recinosa (A.Rich.) Bak. [Fabaceae] is used in combination with the stem barks of Ozoroa insignis Del. (Anacardiaceae), Maytenus senegalensis (Lam.) Excell. [Celastraceae] Entada abyssinica Steud. ex A.Rich [Fabaceae] and Lannea schimperi (Hochst.)Engl. [Anacardiaceae] as a traditional remedy for managing peptic ulcers. However, the safety and efficacy of this polyherbal preparation has not been evaluated. This study reports on the phytochemical profile and some biological activities of the individual plant extracts and a combination of extracts of the five plants.
A mixture of 80% ethanol extracts of R. recinosa, O. insignis, M. senegalensis, E. abyssinica and L. schimperi at doses of 100, 200, 400 and 800 mg/kg body wt were evaluated for ability to protect Sprague Dawley rats from gastric ulceration by an ethanol-HCl mixture. Cytoprotective effect was assessed by comparison with a negative control group given 1% tween 80 in normal saline and a positive control group given 40 mg/kg body wt pantoprazole. The individual extracts and their combinations were also tested for antibacterial activity against four Gram negative bacteria; Escherichia coli (ATCC 25922), Salmonella typhi (NCTC 8385), Vibrio cholerae (clinical isolate), and Klebsiella pneumoniae (clinical isolate) using the microdilution method. In addition the extracts were evaluated for brine shrimp toxicity and acute toxicity in mice. Phytochemical tests were done using standard methods to determine the presence of tannins, saponins, steroids, cardiac glycosides, flavonoids, alkaloids and terpenoids in the individual plant extracts and in the mixed extract of the five plants.
The combined ethanolic extracts of the 5 plants caused a dose-dependent protection against ethanol/HCl induced ulceration of rat gastric mucosa, reaching 81.7% mean protection as compared to 87.5% protection by 40 mg/kg body wt pantoprazole. Both the individual plant extracts and the mixed extracts of 5 plants exhibited weak to moderate antibacterial activity against four G-ve bacteria. Despite Ozoroa insignis being toxic to mice at doses above 1000 mg/kg body wt, the other plant extracts and the combined extract of the 5 plants were tolerated by mice up to 5000 mg/kg body wt. The brine shrimp test results showed the same pattern of toxicity with Ozoroa insignis being the most toxic (LC50 = 10.63 μg/ml). Phytochemical tests showed that the combined extract of the five plants contained tannins, saponins, steroids, cardiac glycosides, flavonoids and terpenoids. Flavonoids, tannins and terpenoids are known to have antioxidant activity.
The combined extract of the five plants exhibited a dose-dependent protective activity in the rat ethanol-HCl gastric ulcer model. The extracts also exhibited weak antibacterial activity against four Gram negative bacteria and low acute toxicity in mice and brine shrimps. Although the results support claims by traditional healers who use a decoction of the five plants for treatment of peptic ulcers, more models of gastric ulceration and proper animal toxicity studies are needed to validate possible clinical use of the polyherbal extract. It is also evident that the doses of the crude extracts showing protection of the gastric mucosa are too large for realistic translation to direct clinical application, but further studies using bioassay guided fractionation are important to either identify more practical fractions or active compound/s.
PMCID: PMC3532137  PMID: 23031266
Ozoroa insignis; Maytenus senegalensis; Entada abyssinica; Lannea schimperi; Gastroprotection; Toxicity
9.  Crocodiles in the Sahara Desert: An Update of Distribution, Habitats and Population Status for Conservation Planning in Mauritania 
PLoS ONE  2011;6(2):e14734.
Relict populations of Crocodylus niloticus persist in Chad, Egypt and Mauritania. Although crocodiles were widespread throughout the Sahara until the early 20th century, increased aridity combined with human persecution led to local extinction. Knowledge on distribution, occupied habitats, population size and prey availability is scarce in most populations. This study evaluates the status of Saharan crocodiles and provides new data for Mauritania to assist conservation planning.
Methodology/Principal Findings
A series of surveys in Mauritania detected crocodile presence in 78 localities dispersed across 10 river basins and most tended to be isolated within river basins. Permanent gueltas and seasonal tâmoûrts were the most common occupied habitats. Crocodile encounters ranged from one to more than 20 individuals, but in most localities less than five crocodiles were observed. Larger numbers were observed after the rainy season and during night sampling. Crocodiles were found dead in between water points along dry river-beds suggesting the occurrence of dispersal.
Research priorities in Chad and Egypt should focus on quantifying population size and pressures exerted on habitats. The present study increased in by 35% the number of known crocodile localities in Mauritania. Gueltas are crucial for the persistence of mountain populations. Oscillations in water availability throughout the year and the small dimensions of gueltas affect biological traits, including activity and body size. Studies are needed to understand adaptation traits of desert populations. Molecular analyses are needed to quantify genetic variability, population sub-structuring and effective population size, and detect the occurrence of gene flow. Monitoring is needed to detect demographical and genetical trends in completely isolated populations. Crocodiles are apparently vulnerable during dispersal events. Awareness campaigns focusing on the vulnerability and relict value of crocodiles should be implemented. Classification of Mauritanian mountains as protected areas should be prioritised.
PMCID: PMC3045445  PMID: 21364897
10.  Antibacterial potential of a basic phospholipase A2 (VRV-PL-VIIIa) from Daboia russelii pulchella (Russell’s viper) venom 
Microbial/bacterial resistance against antibiotics poses a serious threat to public health. Furthermore, the side effects of these antibiotics have stimulated tremendous interest in developing new molecules from diverse organisms as therapeutic agents. This study evaluates the antibacterial potential of a basic protein, Vipera russellii venom phospholipase A2 fraction VIIIa (VRV-PL-VIIIa), from Daboia russelii pulchella venom against gram-positive and gram-negative bacteria.
The antibacterial potential of VRV-PL-VIIIa in the presence and absence of an inhibitor (p-bromophenacyl bromide) was tested against gram-positive and gram-negative bacteria and the minimum inhibitory concentration was determined by microdilution tests.
VRV-PL-VIIIa demonstrated potent antibacterial activities against all the human pathogenic strains tested. It more effectively inhibited such gram-positive bacteria as Staphylococcus aureus and Bacillus subtilis, when compared to the gram-negative bacteria Escherichia coli, Vibrio cholerae, Klebsiella pneumoniae and Salmonella paratyphi. It inhibited bacterial growth at minimum inhibitory concentration values ranging from 11.1 to 19.2 μg/mL. The anti-bacterial potential of VRV-PL-VIIIa was comparable to the standards gentamycin, chlorophenicol and streptomycin. The PLA2’s hemolytic and antibacterial activities were strongly correlated. Furthermore, even in the presence of p-bromophenacyl bromide, intense antibacterial activity was observed, suggesting a dissociation or partial overlapping of the bactericidal/antimicrobial domains.
VRV-PL-VIIIa demonstrated potent antibacterial activities against all the human pathogenic strains tested. The study shows that despite a strong correlation between enzymatic and antimicrobial activities of VRV-PL-VIIIa, it may possess additional properties that mimic the bactericidal/membrane permeability-increasing protein. This study encourages further in-depth studies on the molecular mechanisms of antibacterial properties of VRV-PL-VIIIa, which would thereby facilitate development of this protein into a possible therapeutic lead molecule for treating bacterial infections.
PMCID: PMC4453231  PMID: 26042153
Snake venom; Bactericidal; Antibiotics; Drug; Human pathogenic bacteria
11.  Antioxidant, antibacterial and cytotoxic effects of the phytochemicals of whole Leucas aspera extract 
To investigate the antioxidant, antibacterial and cytotoxic activity of whole Leucas aspera (Labiatae) (L. aspera) alcoholic extract.
Whole L. aspera powder was extracted by absolute ethanol (99.50%). The ethanolic extract was subjected to antioxidant, antibacterial and brine shrimp lethality assay.
The extract showed potent radical scavenging effect (antioxidant) with IC50 value of (99.58±1.22) µg/mL which was significant (P<0.01) in comparison to ascorbic acid with IC50 value of (1.25±0.95) µg/mL. In case of antibacterial screening, the extract showed notable antibacterial effect against the tested microbial strains. Significant (P<0.05) zone of inhibitions against Gram positive Bacillus subtilis [(12.00±1.32) mm] and Bacillus megaterium [(13.00±1.50) mm], Staphylococcus aureus [(8.00±0.50) mm] and Gram negative Salmonella typhi [(6.00±0.50) mm], Salmonella paratyphi [(8.00±1.00) mm], Shigella dysenteriae [(9.00±1.32) mm] and Vibrio cholerae [(9.00±0.66) mm] was observed. In brine shrimp lethality bioassay, the extract showed the LC50 value as (181.68±2.15) µg/mL which was statistically significant (P<0.01) compared to positive control vincristine sulfate [LC50=(0.76±0.04) µg/mL].
The results demonstrate that the ethanolic extract of L. aspera could be used as antibacterial, pesticidal and various pharmacologic actives.
PMCID: PMC3634923  PMID: 23620850
Leucas aspera; Radical scavenging; Antibacterial; Cytotoxic; Probit
12.  Simultaneous, specific and real-time detection of biothreat and frequently encountered food-borne pathogens 
Journal of food protection  2012;75(4):660-670.
The bacterial genera Escherichia, Salmonella, Shigella, Vibrio, Yersinia and Francisella include important food safety and biothreat agents causing food-related and other human illnesses worldwide. We aimed to develop rapid methods with the capability to simultaneously and differentially detect all six pathogens in one run. Our initial experiments to use previously reported sets of primers revealed non-specificity of some of the sequences when tested against a broader array of pathogens, or proved not optimal for simultaneous detection parameters. By extensive mining of the whole genome and protein databases of diverse closely and distantly related bacterial species and strains, we have identified unique genome regions, which we utilized to develop a detection platform. Twelve of the specific genomic targets we have identified to design the primers in F. tularensis ssp. tularensis, F. tularensis ssp. novicida, S. dysentriae, S. typhimurium, V. cholera, Y. pestis, and Y. pseudotuberculosis contained either hypothetical or putative proteins, the functions of which have not been clearly defined. Corresponding primer sets were designed from the target regions for use in real-time PCR assays to detect specific biothreat pathogens at species or strain levels. The primer sets were first tested by in-silico PCR against whole genome sequences of different species, sub-species, or strains and then by in vitro PCR against genomic DNA preparations from 23 strains representing six biothreat agents (E.coli O157:H7 strain EDL 933, Shigella dysentriae, Salmonella typhi, Francisella tularensis ssp. tularensis, Vibrio cholera, and Yersinia pestis) and six foodborne pathogens (Salmonella typhimurium, Salmonella saintpaul, Shigella sonnei, Francisella novicida, Vibrio parahemolytica and Yersinia pseudotuberculosis). Each pathogen was specifically identifiable at the genus and species levels. Sensitivity assays performed using purified DNA showed the lowest detection limit of 640 fg DNA/µl for F. tularensis. A preliminary test done to detect Shigella organisms in a milk matrix showed that 6–60 colony forming units of the bacterium per milliliter of milk could be detected in about an hour. Therefore, we have developed a platform to simultaneously detect foodborne pathogen and biothreat agents specifically and in real-time. Such a platform could enable rapid detection or confirmation of contamination by these agents.
PMCID: PMC3524339  PMID: 22488053
Biothreat agents; PCR; food-borne pathogens
13.  Phytochemical and Antimicrobial Effects of Chrozophora Senegalensis 
The in vitro antimicrobial activities of the whole plant extract (ethanolic-CEE) of Chrozophora senegalensis and its fractions (ethyl acetate-EAA, n-butanol-NBE, aqueous-AQE) were assayed using the agar plate diffusion and nutrient broth dilution methods. Test microorganisms were Bacillus subtilis (NCTC 8326 B76), Escherichia coli (ATCC 11775), Pseudomonas aeruginosa (ATCC 10145), Staphylococcus aureus (ATCC 021001). Aspergillus flavus, Aspergillus niger, Candida albicans and Salmonella typhi - laboratory isolates. CEE, EAA and NBE inhibited all the test bacterial organisms and a fungus-Aspergillus flavus. AQE inhibited only Salmonella typhi and Bacillus subtilis. None of the extracts had activity on other 3 fungal organisms tested. CEE and EAA showed minimum inhibition concentration (MIC) of 0.390 and 3.125 mg/ml against S. typhi and E. coli, while NBE and AQE had MIC of 3.125 and 1.563 mg/ml against S. typhi respectively. NBE had an MIC of 12.500 mg/ml against E. coli. The minimum bactericidal concentration (MBC) of CEE and EAA was found to be <0.098 against S. typhi. The MBC of AQE was 12.5 mg/ml against E. coli and S. aureus, and 6.25 mg/ml towards P. aeruginosa. CEE and EAA exhibited similar antibacterial activities, followed by AQE. The extracts revealed the presence of carbohydrates, tannins, saponins, sterols determined by utilizing standard methods of analysis.
This study has justified the traditional use of the plant for treating diarrhea, boils and syphilis.
PMCID: PMC2816503  PMID: 20161917
Antimicrobial activity; Chrozophora senegalensis; Extracts; Phytochemical Screening; Euphorbiaceae
14.  Antibacterial properties of silver nanoparticles synthesized by marine Ochrobactrum sp 
Brazilian Journal of Microbiology  2015;45(4):1221-1227.
Metal nanoparticle synthesis is an interesting area in nanotechnology due to their remarkable optical, magnetic, electrical, catalytic and biomedical properties, but there needs to develop clean, non-toxic and environmental friendly methods for the synthesis and assembly of nanoparticles. Biological agents in the form of microbes have emerged up as efficient candidates for nanoparticle synthesis due to their extreme versatility to synthesize diverse nanoparticles with varying size and shape. In the present study, an eco favorable method for the biosynthesis of silver nanoparticles using marine bacterial isolate has been attempted. Very interestingly, molecular identification proved it as a strain of Ochrobactrum anhtropi. In addition, the isolate was found to have the potential to form silver nanoparticles intracellularly at room temperature within 24 h. The biosynthesized silver nanoparticles were characterized by UV-Vis spectroscopy, transmission electron microscope (TEM) and scanning electron microscope (SEM). The UV-visible spectrum of the aqueous medium containing silver nanoparticles showed a peak at 450 nm corresponding to the plasmon absorbance of silver nanoparticles. The SEM and TEM micrographs revealed that the synthesized silver nanoparticles were spherical in shape with a size range from 38 nm – 85 nm. The silver nanoparticles synthesized by the isolate were also used to explore its antibacterial potential against pathogens like Salmonella Typhi, Salmonella Paratyphi, Vibrio cholerae and Staphylococcus aureus.
PMCID: PMC4323294  PMID: 25763025
biosynthesis; silver nanoparticles; Ochrobactrum anhtropi; purification; antibacterial activity
15.  The Antibacterial Activity of Cassia fistula Organic Extracts 
Cassia fistula, is a flowering plant and a member of Fabaceae family. Its leaves are compound of 4 - 8 pairs of opposite leaflets. There are many Cassia species around the world which are used in herbal medicine.
This study was designed to examine in vitro anti-bacterial activity of methanolic and ethanolic extracts of C. fistula native to Khuzestan, Iran.
Materials and Methods:
The microbial inhibitory effect of methanolic and ethanolic extracts of C. fistula was tested on 3 Gram positive: Bacillus cereus, Staphylococcus aureus and S. epidermidis and 5 Gram negative: Salmonella Typhi, Kelebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginosa, and Proteus mirabilis bacterial species using disc diffusion method at various concentrations. The minimum inhibitory and bactericidal concentrations (MIC and MBC) were measured by the tube dilution assay.
The extract of C. fistula was effective against B. cereus, S. aureus, S. epidermidis, E. coli and K. pneumoniae. The most susceptible microorganisms to ethanolic and methanolic extracts were E. coli and K. pneumoniae, respectively. Also B. cereus and S. aureus showed the least sensitivity to ethanolic and methanolic extracts, respectively. The MIC (minimum inhibitory concentration) and MBC (minimum bactericidal concentration) of ethanolic extracts against S. aureus, E. coli, S. epidermidis and K. pneumoniae were also determined.
With respect to the obtained results and regarding to the daily increase of the resistant microbial strains to the commercial antibiotics, it can be concluded that these extracts can be proper candidates of antibacterial substance against pathogenic bacterial species especially S. aureus, E. coli, K. pneumoniae and S. epidermidis.
PMCID: PMC4138669  PMID: 25147664
Cassia fistula; Anti-bacterial Activity; Disc Diffusion Antibacterial Test; Minimum Inhibitory Concentration; Minimum Bactericidal Concentration
16.  Epigenetic Activation of Antibacterial Property of an Endophytic Streptomyces coelicolor Strain AZRA 37 and Identification of the Induced Protein Using MALDI TOF MS/MS 
PLoS ONE  2016;11(2):e0147876.
The endophytic Streptomyces coelicolor strain AZRA 37 was isolated from the surface sterilized root of Azadirachta indica A. Juss., commonly known as neem plant in India. Since only a few reports are available regarding epigenetic modulations of microbial entities, S. coelicolor was treated with different concentrations of 5-azacytidine for this purpose and evaluated for its antibacterial potential against five human pathogenic bacteria (Aeromonas hydrophila IMS/GN11, Enterococcus faecalis IMS/GN7, Salmonella typhi MTCC 3216, Shigella flexneri ATCC 12022 and Staphylococcus aureus ATCC 25923). The crude extract obtained from cultures treated with 25 μM concentration of 5-azacytidine, was found effective against all five pathogenic bacteria tested while the untreated control was only active against 3 pathogenic bacteria. HPLC analysis of crude compounds from treated cultures showed a greater number of compounds than that of the control. Extraction of whole cell protein and its SDS PAGE analysis showed an additional major protein band in 25 μM 5-azacytidine treated culture and MALDI TOF MS/MS analysis revealed that this protein belongs to the porin family.
PMCID: PMC4742224  PMID: 26844762
17.  Temporal Fluctuation of Multidrug Resistant Salmonella Typhi Haplotypes in the Mekong River Delta Region of Vietnam 
Typhoid fever remains a public health problem in Vietnam, with a significant burden in the Mekong River delta region. Typhoid fever is caused by the bacterial pathogen Salmonella enterica serovar Typhi (S. Typhi), which is frequently multidrug resistant with reduced susceptibility to fluoroquinolone-based drugs, the first choice for the treatment of typhoid fever. We used a GoldenGate (Illumina) assay to type 1,500 single nucleotide polymorphisms (SNPs) and analyse the genetic variation of S. Typhi isolated from 267 typhoid fever patients in the Mekong delta region participating in a randomized trial conducted between 2004 and 2005.
Principal Findings
The population of S. Typhi circulating during the study was highly clonal, with 91% of isolates belonging to a single clonal complex of the S. Typhi H58 haplogroup. The patterns of disease were consistent with the presence of an endemic haplotype H58-C and a localised outbreak of S. Typhi haplotype H58-E2 in 2004. H58-E2-associated typhoid fever cases exhibited evidence of significant geo-spatial clustering along the Sông H u branch of the Mekong River. Multidrug resistance was common in the established clone H58-C but not in the outbreak clone H58-E2, however all H58 S. Typhi were nalidixic acid resistant and carried a Ser83Phe amino acid substitution in the gyrA gene.
The H58 haplogroup dominates S. Typhi populations in other endemic areas, but the population described here was more homogeneous than previously examined populations, and the dominant clonal complex (H58-C, -E1, -E2) observed in this study has not been detected outside Vietnam. IncHI1 plasmid-bearing S. Typhi H58-C was endemic during the study period whilst H58-E2, which rarely carried the plasmid, was only transient, suggesting a selective advantage for the plasmid. These data add insight into the outbreak dynamics and local molecular epidemiology of S. Typhi in southern Vietnam.
Author Summary
Typhoid fever remains a serious public health issue in some parts of Vietnam, including the Mekong delta region. Typhoid is caused by the bacterium Salmonella Typhi, which is frequently multidrug resistant and shows reduced susceptibility to fluoroquinolone-based drugs. We assayed single nucleotide variation in the genomes of S. Typhi organisms isolated from 267 patients with typhoid fever in the Mekong delta between 2004 and 2005, and identified genetically distinct S. Typhi strains. We also detected the presence of genes or mutations that confer drug resistance in those strains. We found that the vast majority of typhoid cases were caused by one of two subgroups of H58 S. Typhi, referred to as H58-C and H58-E2. The H58-E2 group appeared to cause an outbreak in 2004, affecting patients living in a small zone near the Mekong River. The other group, H58-C, was present throughout the study period and affected patients living in a broader area of the Mekong River delta. Most of the H58-C strains were resistant to multiple drugs and carried a plasmid encoding multiple resistance genes. However very few H58-E2 strains were multidrug resistant, which may explain why the strain did not persist after the initial outbreak.
PMCID: PMC3014949  PMID: 21245916
18.  In vitro antibacterial evaluation of Anabaena sp. against several clinically significant microflora and HPTLC analysis of its active crude extracts 
Indian Journal of Pharmacology  2010;42(2):105-107.
The present study was conducted to evaluate the possible antibacterial activity of Anabaena extracts. Anabaena was isolated from a natural source and cultured in vitro. after suitable growth, cyanobacterial culture was harvested using different solvents. Extracts, thus prepared, were evaluated for their antibacterial potential by agar-well diffusion assay against bacterial species of clinical significance. MIC values were determined further to check the concentration ranges for significant inhibition. HPTLC analysis was done to separate the components of active crude extract in an attempt to identify the bio-active chemical entity. Methanol extract exhibited more potent activity than that of hexane and ethyl acetate extracts. No inhibitory effect was found against Pseudomonas aeruginosa, Salmonella typhi, and Klebsiella pneumoniae. Staphylococcus aureus required about 256 µg/ml of the crude methanol extract for effective inhibition. HPTLC evaluation at λ 254 nm was performed for the separation of a complex mixture of the methanol extract. The results provide evidence that Anabaena sp. extracts might indeed be potential sources of new antibacterial agents.
PMCID: PMC2907006  PMID: 20711376
Blue-green algae; drug-resistance; biologically active substances; bacterial species
19.  Antimicrobial activity, acute toxicity and cytoprotective effect of Crassocephalum vitellinum (Benth.) S. Moore extract in a rat ethanol-HCl gastric ulcer model 
BMC Research Notes  2014;7:91.
A decoction of Crassocephallum vitellinum (Benth.) S. Moore (Asteraceae) is used in Kagera Region to treat peptic ulcers. This study seeks to evaluate an aqueous ethanol extract of aerial parts of the plant for safety and efficacy.
An 80% ethanolic extract of C. vitellinum at doses of 100, 200, 400 and 800 mg/kg body wt was evaluated for ability to protect Sprague Dawley rats from acidified ethanol gastric ulceration in comparison with 40 mg/kg body wt pantoprazole. The extract and its dichloromethane, ethyl acetate, and aqueous fractions were also evaluated for acute toxicity in mice, brine shrimp toxicity, and antibacterial activity against four Gram negative bacteria; Escherichia coli (ATCC 25922), Salmonella typhi (NCTC 8385), Vibrio cholera (clinical isolate), and Streptococcus faecalis (clinical isolate). The groups of phytochemicals present in the extract were also determined.
The ethanolic extract of C. vitellinum dose-dependently protected rat gastric mucosa against ethanol/HCl insult to a maximum of 88.3% at 800 mg/kg body wt, affording the same level of protection as by 40 mg/kg body wt pantoprazole. The extract also exhibited weak antibacterial activity against S. typhi and E. coli, while its ethyl acetate, dichloromethane and aqueous fractions showed weak activity against K. pneumonia, S.typhi, E. coli and V. cholera. The extract was non-toxic to mice up to 5000 mg/kg body wt, and the total extract (LC50 = 37.49 μg/ml) and the aqueous (LC50 = 87.92 μg/ml), ethyl acetate (LC50 = 119.45 μg/ml) and dichloromethane fractions (88.79 μg/ml) showed low toxicity against brine shrimps. Phytochemical screening showed that the extract contains tannins, saponins, flavonoids, and terpenoids.
The results support the claims by traditional healers that a decoction of C.vitellinum has antiulcer activity. The mechanism of cytoprotection is yet to be determined but the phenolic compounds present in the extract may contribute to its protective actions. However, the dose conferring gastro-protection in the rat is too big to be translated to clinical application; thus bioassay guided fractionation to identify active compound/s or fractions is needed, and use of more peptic ulcer models to determine the mechanism for the protective action.
PMCID: PMC3932038  PMID: 24552147
Crassocephalum vitellinum; Traditional medicine; Gastric cytoprotection; Antimicrobial; Acute, Toxicity
20.  Interferon-γ and Proliferation Responses to Salmonella enterica Serotype Typhi Proteins in Patients with S. Typhi Bacteremia in Dhaka, Bangladesh 
Salmonella enterica serotype Typhi is a human-restricted intracellular pathogen and the cause of typhoid fever. Cellular immune responses are required to control and clear Salmonella infection. Despite this, there are limited data on cellular immune responses in humans infected with wild type S. Typhi.
Methodology/Principal Findings
For this work, we used an automated approach to purify a subset of S. Typhi proteins identified in previous antibody-based immuno-affinity screens and antigens known to be expressed in vivo, including StaF-putative fimbrial protein-STY0202, StbB-fimbrial chaperone-STY0372, CsgF-involved in curli production-STY1177, CsgD- putative regulatory protein-STY1179, OppA-periplasmic oligopeptide binding protein precursor-STY1304, PagC-outer membrane invasion protein-STY1878, and conserved hypothetical protein-STY2195; we also generated and analyzed a crude membrane preparation of S. Typhi (MP). In comparison to samples collected from uninfected Bangladeshi and North American participants, we detected significant interferon-γ responses in PBMCs stimulated with MP, StaF, StbB, CsgF, CsgD, OppA, STY2195, and PagC in patients bacteremic with S. Typhi in Bangladesh. The majority of interferon-γ expressing T cells were CD4 cells, although CD8 responses also occurred. We also assessed cellular proliferation responses in bacteremic patients, and confirmed increased responses in infected individuals to MP, StaF, STY2195, and PagC in convalescent compared to acute phase samples and compared to controls. StaF is a fimbrial protein homologous to E. coli YadK, and contains a Pfam motif thought to be involved in cellular adhesion. PagC is expressed in vivo under the control of the virulence-associated PhoP-regulon required for intra-macrophage survival of Salmonella. STY2195 is a conserved hypothetical protein of unknown function.
This is the first analysis of cellular immune responses to purified S. Typhi antigens in patients with typhoid fever. These results indicate that patients generate significant CD4 and CD8 interferon-γ responses to specific S. Typhi antigens during typhoid fever, and that these responses are elevated at the time of clinical presentation. These observations suggest that an interferon-γ based detection system could be used to diagnose individuals with typhoid fever during the acute stage of illness.
Author Summary
Salmonella enterica serotype Typhi infection is a significant global public health problem and the cause of typhoid fever. Salmonella are intracellular pathogens, and cellular immune responses are required to control and clear Salmonella infections. Despite this, there are limited data on cellular immune responses during wild type S. Typhi infection in humans. Here we report the assessment of cellular immune responses in humans with S. Typhi bacteremia through a screening approach that permitted us to evaluate interferon-γ and proliferation responses to a number of S. Typhi antigens. We detected significant interferon-γ CD4 and CD8 responses, as well as proliferative responses, to a number of recombinantly purified S. Typhi proteins as well as membrane preparation in infected patients. Antigen-specific interferon-γ responses were present at the time of clinical presentation in patients and absent in healthy controls. These observations could assist in the development of interferon-γ-based diagnostic assays for typhoid fever.
PMCID: PMC3110156  PMID: 21666798
21.  Antibacterial and Antioxidant Activities of Acid and Bile Resistant Strains of Lactobacillus fermentum Isolated from Miang 
Brazilian Journal of Microbiology  2009;40(4):757-766.
Miang is a kind of traditional fermented tea leaves, widely consumed in northern Thailand as a snack. It contains several kinds of Lactobacilli spp. The aim of this study was to isolate strains of Lactobacillus fermentum from miang and to investigate their antibacterial and antioxidant activities. The agar spot and well assays were used for determination of antibacterial power. The antibacterial mechanism was investigated by cell morphologic change under scanning electron microscope (SEM). Antioxidant activity was studied by means of free radical scavenging and ferric reducing power assays. The acid and bile screening tests indicated that L. fermentum FTL2311 and L. fermentum FTL10BR presented antibacterial activity against several pathogenic bacteria: Listeria monocytogenes DMST 17303, Salmonella Typhi DMST 5784, Shigella sonnei DMST 561 (ATCC 11060) and Staphylococcus aureus subsp. aureus DMST 6512 (ATCC 6538Ptm). The results from SEM suggested that the antibacterial action was due to the destruction of cell membrane which consequently caused the pathogenic cell shrinking or cracking. The antioxidant study suggested that both L. fermentum FTL2311 and L. fermentum FTL10BR strains could liberate certain substances that possessed antioxidant activity expressed as trolox equivalent antioxidant capacity (TEAC) and equivalent concentration (EC) values for free radical scavenging and reducing mechanisms, respectively. The supernatant of L. fermentum FTL2311 broth revealed TEAC and EC values of 22.54±0.12 and 20.63±0.17 > respectively, whereas that of L. fermentum FTL10BR yielded TEAC and EC values of 24.09±0.12 and 21.26±0.17 > respectively. These two strains isolated from miang present high potential as promising health-promoting probiotics.
PMCID: PMC3768562  PMID: 24031422
Lactobacillus fermentum; miang; bile resistance; antibacterial activity; antioxidant activity
22.  In Vitro Antibacterial Activity of Ibuprofen and Acetaminophen 
Ibuprofen and acetaminophen are common chemical agents that have anti-inflammatory, antipyretic, and analgesic activity.
To detect any potential antibacterial effects of ibuprofen and acetaminophen on pathogenic bacteria.
Materials and methods:
Ibuprofen and acetaminophen were tested for antibacterial activity against seven isolates of bacteria including gram positive bacteria (Staphylococci aureus and Bacillus subtilis) and gram negative bacteria (E. coli, Enterobacter aerogenes, Enterobacter cloacae, Salmonella typhi and Paracoccus yeei). Spectrophotometer assay was applied to determine the antibacterial activities of ibuprofen and acetaminophen. Three controls were included in this study: Ampicilline sodium (20 μg/ml); cefotaxime sodium (20 μg/ml) and chemical free medium.
Staphylococcus aureus and Paracoccus yeei were susceptible to lower concentrations of ibuprofen and acetaminophen (MIC=1.25 mg/ml), while two strains of Enterobacter exhibited resistance to these agents.
Ibuprofen and acetaminophen showed a potential antibacterial effect on isolated strains of bacteria. They had the same ability to inhibit bacterial growth.
PMCID: PMC2889646  PMID: 20606962
Acetaminophen; Antibacterial; Ibuprofen
23.  In vitro antibacterial potency of Butea monosperma Lam. against 12 clinically isolated multidrug resistant bacteria 
To investigate the antibacterial activity, using cold and hot extraction procedures with five solvents, petroleum ether, acetone, ethanol, methanol and water to validate medicinal uses of Butea monosperma Lam (B. monosperma) in controlling infections; and to qualitatively estimate phytochemical constituents of leaf-extracts of the plant.
The antibacterial activity of leaf-extracts was evaluated by the agar-well diffusion method against clinically isolated 12 Gram-positive and -negative multidrug resistant (MDR) pathogenic bacteria in vitro. Values of minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of leaf-extracts against each bacterium were obtained in a 96-well micro-titre plate, by broth dilution micro-titre plate technique.
The presence of tannins, flavonoids, starch, glycosides and carbohydrates in different leaf extracts was established. Pathogenic bacteria used were, Acinetobacter sp., Chromobacterium violaceum, Citrobacter freundii, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Salmonella typhi, Shigella sp., Enterococcus sp., Staphylococcus aureus (S. aureus), methicillin resistant S. aureus and vancomycin resistant S. aureus, along with standard bacterial strains. These MDR bacteria had been recorded to have significant inhibitions by leaf extracts, obtained by cold and hot extraction procedures with five solvents. In addition, the hot aqueous extract against Enterococcus sp. had the highest inhibition zone-size (21 mm). Ciprofloxacin 30 µg/disc was the positive/reference control and the diluting solvent, 10% dimethyl sulphoxide was the negative control. Recorded MIC values of different extracts ranged between 0.23 and 13.30 mg/mL, and MBC values were 0.52 to 30.00 mg/mL, for these bacteria.
Leaf-extracts with hot water and ethanol had shown significant antibacterial activity against all bacteria. B. monosperma leaf-extract could be used in treating infectious diseases, caused by the range of tested bacteria, as complementary and alternate medicine.
PMCID: PMC4027298
Butea monosperma; Gram-positive bacteria; Gram-negative bacteria; Multidrug resistant bacteria; Minimum inhibitory concentration; Antibacterial activity; Phytochemical constituents
24.  A C-Type Lectin from Bothrops jararacussu Venom Disrupts Staphylococcal Biofilms 
PLoS ONE  2015;10(3):e0120514.
Bovine mastitis is a major threat to animal health and the dairy industry. Staphylococcus aureus is a contagious pathogen that is usually associated with persistent intramammary infections, and biofilm formation is a relevant aspect of the outcome of these infections. Several biological activities have been described for snake venoms, which led us to screen secretions of Bothrops jararacussu for antibiofilm activity against S. aureus NRS155. Crude venom was fractionated by size-exclusion chromatography, and the fractions were tested against S. aureus. Biofilm growth, but not bacterial growth, was affected by several fractions. Two fractions (15 and 16) showed the best activities and were also assayed against S. epidermidis NRS101. Fraction 15 was identified by TripleTOF mass spectrometry as a galactose-binding C-type lectin with a molecular weight of 15 kDa. The lectin was purified from the crude venom by D-galactose affinity chromatography, and only one peak was observed. This pure lectin was able to inhibit 75% and 80% of S. aureus and S. epidermidis biofilms, respectively, without affecting bacterial cell viability. The lectin also exhibited a dose-dependent inhibitory effect on both bacterial biofilms. The antibiofilm activity was confirmed using scanning electron microscopy. A pre-formed S. epidermidis biofilm was significantly disrupted by the C-type lectin in a time-dependent manner. Additionally, the lectin demonstrated the ability to inhibit biofilm formation by several mastitis pathogens, including different field strains of S. aureus, S. hyicus, S. chromogenes, Streptococcus agalactiae, and Escherichia coli. These findings reveal a new activity for C-type lectins. Studies are underway to evaluate the biological activity of these lectins in a mouse mastitis model.
PMCID: PMC4374669  PMID: 25811661
25.  Mucosal and Systemic Immune Responses in Humans after Primary and Booster Immunizations with Orally Administered Invasive and Noninvasive Live Attenuated Bacteria 
Infection and Immunity  1999;67(7):3680-3685.
The mucosal and systemic immune responses after primary and booster immunizations with two attenuated live oral vaccine strains derived from a noninvasive (Vibrio cholerae) and an invasive (Salmonella typhi) enteric pathogen were comparatively evaluated. Vaccination with S. typhi Ty21a elicited antibody-secreting cell (ASC) responses specific for S. typhi O9, 12 lipopolysaccharide (LPS), as well as significant increases in levels of immunoglobulin G (IgG) and IgA antibodies to the same antigen in serum. A strong systemic CD4+ T-helper type 1 cell-mediated immune (CMI) response was also induced. In contrast to results with Ty21a, no evidence of a CMI response was obtained after primary immunization with V. cholerae CVD 103-HgR in spite of the good immunogenicity of the vaccine. Volunteers who received a single dose of CVD 103-HgR primarily developed an IgM ASC response against whole vaccine cells and purified V. cholerae Inaba LPS, and seroconversion of serum vibriocidal antibodies occurred in four of five subjects. Serum IgG anti-cholera toxin antibody titers were of lower magnitude. For both live vaccines, the volunteers still presented significant local immunity 14 months after primary immunization, as revealed by the elevated baseline antibody titers at the time of the booster immunization and the lower ASC, serum IgG, and vibriocidal antibody responses after the booster immunization. These results suggest that local immunity may interfere with colonization of the gut by both vaccine strains at least up to 14 months after basis immunization. Interestingly, despite a low secondary ASC response, Ty21a was able to boost both humoral (anti-LPS systemic IgG and IgA) and CMI responses. Evidence of a CMI response was also observed for one of three volunteers given a cholera vaccine booster dose. The direct comparison of results with two attenuated live oral vaccine strains in human volunteers clearly showed that the capacity of the vaccine strain to colonize specific body compartments conditions the pattern of vaccine-induced immune responses.
PMCID: PMC116565  PMID: 10377160

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