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1.  Diversity of Salmonella Isolates from Central Florida Surface Waters 
Applied and Environmental Microbiology  2014;80(21):6819-6827.
Identification of Salmonella serotypes is important for understanding the environmental diversity of the genus Salmonella. This study evaluates the diversity of Salmonella isolates recovered from 165 of 202 Central Florida surface water samples and investigates whether the serotype of the environmental Salmonella isolates can be predicted by a previously published multiplex PCR assay (S. Kim, J. G. Frye, J. Hu, P. J. Fedorka-Cray, R. Gautom, and D. S. Boyle, J. Clin. Microbiol. 44:3608–3615, 2006, Multiplex PCR was performed on 562 Salmonella isolates (as many as 36 isolates per water sample) to predict serotypes. Kauffmann-White serogrouping was used to confirm multiplex PCR pattern groupings before isolates were serotyped, analyzed by pulsed-field gel electrophoresis, and assayed for antimicrobial susceptibility. In 41.2% of the Salmonella-positive water samples, all Salmonella isolates had identical multiplex PCR patterns; in the remaining 58.8%, two or more multiplex PCR patterns were identified. Within each sample, isolates with matching multiplex PCR patterns had matching serogroups. The multiplex patterns of 495 isolates (88.1%) did not match any previously reported pattern. The remaining 68 isolates matched reported patterns but did not match the serotypes for those patterns. The use of the multiplex PCR allowed the number of isolates requiring further analysis to be reduced to 223. Thirty-three Salmonella enterica serotypes were identified; the most frequent included serotypes Muenchen, Rubislaw, Anatum, Gaminara, and IV_50:z4,z23:−. A majority (141/223) of Salmonella isolates clustered into one genotypic group. Salmonella isolates in Central Florida surface waters are serotypically, genotypically, and phenotypically (in terms of antimicrobial susceptibility) diverse. While isolates could be grouped as different or potentially the same using multiplex PCR, the multiplex PCR pattern did not predict the Salmonella serotype.
PMCID: PMC4249054  PMID: 25172861
2.  Bacteriophages for managing Shigella in various clinical and non-clinical settings 
Bacteriophage  2013;3(1):e25098.
The control of shigellosis in humans enjoys a prominent position in the history of bacteriophage therapy. d’Herelle first demonstrated the efficacy of phage therapy by curing 4 patients of shigellosis, and several subsequent studies confirmed the ability of phages to reduce Shigella based infection. Shigella spp continue to cause millions of illnesses and deaths each year and the use of phages to control the disease in humans and the spread of the bacteria within food and water could point the way forward to the effective management of an infectious disease with global influence.
PMCID: PMC3694061  PMID: 23819110
shigellosis; control; bacteriophage therapy; food safety; shiga toxins
3.  Phage-based biocontrol strategies to reduce foodborne pathogens in foods 
Bacteriophage  2011;1(3):130-137.
There has been much recent interest in the use of phages as biocontrol agents of foodborne pathogens in animals used for food production, and in the food products themselves. This interest seems to be driven by consumers' request for more natural foods, as well as the fact that foodborne outbreaks continue to occur, globally, in many foods, some of which (such as fresh produce), lack adequate methods to control any pathogenic contamination present. Also, the many successes with respect to regulatory approval of phage based products destined for use in foods is leading to an increase in the number of phage products that are commercially available. At present, these products are directed against three main foodborne pathogens including Escherichia coli O157:H7, Salmonella spp and Listeria monocytogenes. In the future, it is likely that new phage products will be targeted against emerging foodborne pathogens. Here, we review the current literature and status of phage based strategies aimed at reducing the presence of foodborne pathogenic bacteria in food and the food production environment.
PMCID: PMC3225777  PMID: 22164346
bacteriophage; biocontrol; food safety; bacterial foodborne pathogens; pre-harvest; post-harvest
4.  Luminescence based enzyme-labeled phage (Phazyme) assays for rapid detection of Shiga toxin producing Escherichia coli serogroups 
Bacteriophage  2011;1(2):101-110.
Most diagnostic approaches for Shiga toxin producing Escherichia coli (STEC) have been designed to detect only serogroup O157 that causes a majority, but not all STEC related outbreaks in the United States. Therefore, there is a need to develop methodology that would enable the detection of other STEC serogroups that cause disease. Three bacteriophages (phages) that infect STEC serogroups O26, O103, O111, O145 and O157 were chemically labeled with horseradish peroxidase (HRP). The enzyme-labeled phages (Phazymes) were individually combined with a sampling device (a swab), STEC serogroup-specific immunomagnetic separation (IMS) beads, bacterial enrichment broth and luminescent HRP substrate, in a self-contained test device, while luminescence was measured in a hand-held luminometer.
The O26 and O157 Phazyme assays correctly identified more than 93% of the bacteria tested during this study, the O123 Phazyme assay identified 89.6%, while the O111 and O145 Phazyme assays correctly detected 82.4% and 75.9%, respectively. The decreased specificity of the O111 and O145 assays was related to the broad host ranges of the phages used in both assays. The Phazyme assays were capable of directly detecting between 105 and 106 CFU/ml in pure culture, depending on the serogroup. In food trials, the O157 Phazyme assay was able to detect E. coli O157:H7 in spinach consistently at levels of 1 CFU/g and occasionally at levels of 0.1 CFU/g. The assay detected 100 CFU/100 cm2 on swabbed meat samples and 102 CFU/100 ml in water samples. The Phazyme assay effectively detects most STEC in a simple and rapid manner, with minimal need for instrumentation to interpret the test result.
PMCID: PMC3278647  PMID: 22334866
Shiga toxin producing Escherichia coli (STEC); rapid detection; enzyme-labeled phages (Phazymes); horseradish peroxidase (HRP); swab; hand held luminometer
5.  Predicting Salmonella Populations from Biological, Chemical, and Physical Indicators in Florida Surface Waters 
Applied and Environmental Microbiology  2013;79(13):4094-4105.
Coliforms, Escherichia coli, and various physicochemical water characteristics have been suggested as indicators of microbial water quality or index organisms for pathogen populations. The relationship between the presence and/or concentration of Salmonella and biological, physical, or chemical indicators in Central Florida surface water samples over 12 consecutive months was explored. Samples were taken monthly for 12 months from 18 locations throughout Central Florida (n = 202). Air and water temperature, pH, oxidation-reduction potential (ORP), turbidity, and conductivity were measured. Weather data were obtained from nearby weather stations. Aerobic plate counts and most probable numbers (MPN) for Salmonella, E. coli, and coliforms were performed. Weak linear relationships existed between biological indicators (E. coli/coliforms) and Salmonella levels (R2 < 0.1) and between physicochemical indicators and Salmonella levels (R2 < 0.1). The average rainfall (previous day, week, and month) before sampling did not correlate well with bacterial levels. Logistic regression analysis showed that E. coli concentration can predict the probability of enumerating selected Salmonella levels. The lack of good correlations between biological indicators and Salmonella levels and between physicochemical indicators and Salmonella levels shows that the relationship between pathogens and indicators is complex. However, Escherichia coli provides a reasonable way to predict Salmonella levels in Central Florida surface water through logistic regression.
PMCID: PMC3697547  PMID: 23624476

Results 1-5 (5)