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Journal of Bacteriology  1963;85(4):918-926.
Bateman, J. B. (U.S. Army Biological Laboratories, Fort Detrick, Frederick, Md.) and F. Elizabeth White. Effect of relative humidity on the survival of Serratia marcescens in concentrated glycerol and sucrose solutions. J. Bacteriol. 85:918–926. 1963.—The effects of sucrose and glycerol upon the ability of Serratia marcescens to grow when restored to a normal medium after exposure to solutions of these substances were examined, with special attention to the prevailing thermodynamic activity of water in these solutions as a factor of supposed primary importance in influencing survival or death of cells. The data were notable for the absence of any zones of instability such as those found when the water activity is changed by exposure of washed cells to water vapor at controlled relative humidities (RH). The cells survived indefinitely at room temperature in concentrated sucrose solutions; in glycerol solutions of equilibrium RH values from 20 to 90, the first-order decay constants were about 0.03 to 0.1 hr−1. These results, considered together with the contrasting phenomenon of narrow lethal humidity zones found in vapor-phrase equilibration experiments, were explained generally in terms of competitive interactions involving concentrated intrinsic and adventitious solutes, the cell water, and the organized structures of the cell, whose integrity was considered to depend ultimately upon the net effect of these various interactions.
PMCID: PMC278245  PMID: 14044963
2.  Growth and survival of Serratia marcescens under aerobic and anaerobic conditions in the presence of materials from blood bags. 
Journal of Clinical Microbiology  1993;31(7):1826-1830.
Several patients receiving blood transfusions during the summer of 1991 developed bacteremia after the transfusion. In all cases, the infection was caused by Serratia marcescens. The same strain of Serratia marcescens was isolated from the patients and from the outer surface of unfilled blood bags. The transport containers for the blood bags were made anoxic by using a catalyst in order to prevent microbial growth. The survival and growth of S. marcescens K202, which was isolated from the blood bags, was studied at different oxygen concentrations in deionized water containing materials derived from the blood bags. The rate of survival and growth of S. marcescens was highest under anaerobic conditions, in which growth occurred with all materials and even in deionized water alone. In contrast, S. marcescens did not survive in control cultures under semi-anaerobic and aerobic conditions. Growth was observed, however, under both aerobic and semi-anaerobic conditions in the presence of each of the tested blood bag materials. These findings indicate that the conditions in the transport containers for the blood bags were favorable for the survival and growth of S. marcescens.
PMCID: PMC265640  PMID: 8349760
3.  Relationship Between Atmospheric Temperature and Survival of Airborne Bacteria 
Applied Microbiology  1970;19(2):245-249.
Effects of temperatures ranging from −40 to 49 C on the behavior of airborne Serratia marcescens, Escherichia coli, and Bacillus subtilis var. niger were investigated. Aerosol decay rates of B. subtilis spores were not significantly affected by the temperature and remained approximately constant within the temperature range studied. The survival of airborne S. marcescens and E. coli was closely related to the temperature. An increase in temperature from −18 to 49 C resulted in a progressive increase of the biological death rate, and the relationship between the biological death rate and the temperature appeared to be linear. An increase in temperature from 24 to 49 C resulted in significantly reduced aerosol recoveries of the two vegetative organisms. At −40 C, the aerosol recovery of all three agents was consistently lower than at −18 to 24 C.
PMCID: PMC376659  PMID: 4985428
4.  Relative Humidity and the Killing of Bacteria 
Applied Microbiology  1961;9(6):567-571.
The viability of washed moist cells of Serratia marcescens after storage has been measured in relation to variations in the prior treatment of the cells and in conditions of storage. The factors considered were: (i) water content during storage; (ii) method of arriving at water content (partial drying in vacuum or freeze-drying and addition of water); (iii) presence or absence of air during storage.
Increasingly rapid decay occurs as the water content at which the cells are stored is diminished from above 90% to 20 or 30% (“critical” water content). It occurs in presence or absence of air and it occurs whether the final water content is approached by removal of water from wet cells or by addition of water to freeze-dried cells.
The rate of decay during storage at 20 to 30% water is somewhat diminished by the presence of air (“protective” effect of air).
As the water content is further reduced to less than 10%, the stability of cells stored in a vacuum approaches that of wet cells. In presence of air the reverse is true: the stability decreases until at less than 1% water, the decay rate is about as great as at the “critical” water content (“toxic” effect of air).
Particularly rapid decay of S. marcescens at the “critical” water content has escaped attention in aerosol studies because accurate control of relative humidity (RH) in this region, RH 94 to 99%, is virtually impossible in such studies. On the other hand, values of decay rates referred to measured water contents are quite unreliable in the 20 to 80% RH zone because the corresponding variation of water content is too small to measure reliably. Thus data of the kind reported in this paper cannot be directly compared to the published results of studies of air-borne bacteria, although they are relevant to the practical question of air-borne infection in humid atmospheres.
PMCID: PMC1057789  PMID: 13865722
5.  Size and UV Germicidal Irradiation Susceptibility of Serratia marcescens when Aerosolized from Different Suspending Media 
Experimental systems have been built in laboratories worldwide to investigate the influence of various environmental parameters on the efficacy of UV germicidal irradiation (UVGI) for deactivating airborne microorganisms. It is generally recognized that data from different laboratories might vary significantly due to differences in systems and experimental conditions. In this study we looked at the effect of the composition of the suspending medium on the size and UVGI susceptibility of Serratia marcescens in an experimental system built in our laboratory. S. marcescens was suspended in (i) distilled water, (ii) phosphate buffer, (iii) 10% fetal calf serum, (iv) phosphate-buffered saline (saline, 0.8% sodium chloride), and (v) synthetic saliva (phosphate-buffered saline with 10% fetal calf serum). At low humidity (36%), S. marcescens suspended in water-only medium was the most susceptible to UVGI, followed by those in serum-only medium. The count median diameters (CMDs) for culturable particles from water-only and serum-only media were 0.88 and 0.95 μm, respectively, with the measurements based on their aerodynamic behavior. The bacteria suspended in phosphate buffer, synthetic saliva, and phosphate-buffered saline had similar UVGI susceptibility and CMD at 1.0, 1.4, and 1.5 μm, respectively. At high humidity (68%) the CMD of the particles increased by 6 to 16%, and at the same time UVGI susceptibility decreased, with the magnitude of decrease related to the type of suspending medium. In conclusion, the choice of suspending medium influenced both size and UVGI susceptibility of S. marcescens. These data are valuable for making comparisons and deciding on the use of an appropriate medium for various applications.
PMCID: PMC383042  PMID: 15066792
Journal of Bacteriology  1962;84(6):1297-1302.
Zimmerman, Leonard (U.S. Army Biological Laboratories, Fort Detrick, Frederick, Md.). Survival of Serratia marcescens after freeze-drying or aerosolization at unfavorable humidity. I. Effects of sugars. J. Bacteriol. 84:1297–1302. 1962.—Suspensions of Serratia marcescens were subjected to freeze-drying or to aerosolization at unfavorable humidity levels. The survival of the cells during one or the other of these treatments was markedly improved in the presence of common sugars, but no one sugar stabilized the cells against both stresses. The protective effects of the sugars were correlated with their penetrability into cells; minimally penetrable sugars stabilized cells against aerosolization, and freely penetrable sugars stabilized cells during freeze-drying. These results were attributed to the modifications of intracellular water content induced by the presence of the sugars in the cell suspensions.
PMCID: PMC278062  PMID: 14003706
7.  Effects of Oxygen on Aerosolized Serratia marcescens 
Applied Microbiology  1965;13(5):781-787.
Suspensions of Serratia marcescens (ATCC strain 14041) in water were aerosolized in a rotating drum in the presence of various concentrations of oxygen. The colony-forming ability of aerosolized organisms was rapidly destroyed by contact with 0.25% or more oxygen at 40% relative humidity (RH) and 25 C, but was almost unimpaired for at least 5 hr in nitrogen containing not more than 10 ppm of oxygen. Completely hydrated organisms were insensitive to oxygen at pressures up to 100 psi for 4 hr. No loss in viability occurred in aerosols of washed cells in air at 97% RH. It is proposed that dehydration of the aerosolized cell results in sensitization to lethal effects of oxygen, but is not the primary cause of death. Mn++, Co++, glycerol, and thiourea enhanced the biological stability of aerosols in air. Numerous similarities between the effects of oxygen in this system and in systems using freeze-dried or irradiated organisms or cell-free enzymes support the hypothesis that closely related mechanisms are involved.
PMCID: PMC1058343  PMID: 5325941
8.  Kinetic Analysis of Growth Rate, ATP, and Pigmentation Suggests an Energy-Spilling Function for the Pigment Prodigiosin of Serratia marcescens▿  
Journal of Bacteriology  2008;190(22):7453-7463.
Serratia marcescens is a gram-negative environmental bacterium and opportunistic pathogen. S. marcescens expresses prodigiosin, a bright red and cell-associated pigment which has no known biological function for producing cells. We present here a kinetic model relating cell, ATP, and prodigiosin concentration changes for S. marcescens during cultivation in batch culture. Cells were grown in a variety of complex broth media at temperatures which either promoted or essentially prevented pigmentation. High growth rates were accompanied by large decreases in cellular prodigiosin concentration; low growth rates were associated with rapid pigmentation. Prodigiosin was induced most strongly during limited growth as the population transitioned to stationary phase, suggesting a negative effect of this pigment on biomass production. Mathematically, the combined rate of formation of biomass and bioenergy (as ATP) was shown to be equivalent to the rate of prodigiosin production. Studies with cyanide inhibition of both oxidative phosphorylation and pigment production indicated that rates of biomass and net ATP synthesis were actually higher in the presence of cyanide, further suggesting a negative regulatory role for prodigiosin in cell and energy production under aerobic growth conditions. Considered in the context of the literature, these results suggest that prodigiosin reduces ATP production by a process termed energy spilling. This process may protect the cell by limiting production of reactive oxygen compounds. Other possible functions for prodigiosin as a mediator of cell death at population stationary phase are discussed.
PMCID: PMC2576671  PMID: 18805986
9.  Structure and function of a bacterial mRNA stabilizer: analysis of the 5' untranslated region of ompA mRNA. 
Journal of Bacteriology  1991;173(15):4578-4586.
The 5' untranslated region (UTR) of the Escherichia coli ompA transcript functions in vivo as a growth rate-regulated mRNA stabilizer. The secondary structure of this mRNA segment has been determined by a combination of three methods: phylogenetic analysis, in vitro probing with a structure-specific RNase, and methylation by dimethylsulfate in vivo and in vitro. These studies reveal that despite extensive sequence differences, the 5' UTRs of the ompA transcripts of E. coli, Serratia marcescens, and Enterobacter aerogenes can fold in a remarkably similar fashion. Furthermore, the Serratia and Enterobacter ompA 5' UTRs function as effective mRNA stabilizers in E. coli. Stabilization of mRNA by the Serratia ompA 5' UTR is growth rate dependent. These findings indicate that the features of the ompA 5' UTR responsible for its ability to stabilize mRNA in a growth rate-regulated manner are to be found among the structural similarities shared by these diverse evolutionary variants.
PMCID: PMC208132  PMID: 1713205
10.  Survival of Airborne Bacteria in a High Urban Concentration of Carbon Monoxide1 
Applied Microbiology  1973;25(1):86-91.
Vegetative cells of Serratia marcescens 8UK, Sarcina lutea, and spores of Bacillus subtilus var. niger were held in aerosols, with and without an urban concentration of CO (85 μliters per liter or ppm), for up to 6 hr at 15 C and a relative humidity (RH) of approximately 0, 25, 50, 75, and 95%. It was found that CO enhanced the death rate of S. marcescens 8UK at least four- to sevenfold at low RH (ca. 1 to 25%), but protected the cells at high RH (ca. 90%). Death rates of S. lutea, with or without added CO, were comparatively low over the entire RH range. However, in the first hour, airborne S. lutea held in CO-containing air were more stable than those in air without added CO (i.e., CO protection). A marked increase in the death rate (up to 70-fold) occurred in the subsequent 5 hr within the RH range of approximately 0 to 75%. Statistical analysis indicated that aerosol decay rates of B. subtilus var. niger spores decreased significantly, when held in a CO-containing as compared to a non-CO-containing atmosphere, in the 0 to 85% RH range. Thus, the data presented indicate that CO in the urban environment may have a protective or lethal effect on airborne bacteria, dependent upon at least the microbial species, aerosol age, and relative humidity. A mechanism for CO death enhancement and protection of airborne S. marcescens 8UK is suggested to involve CO uncoupling of an energy-requiring death mechanism and an energy-requiring maintenance mechanism at high and low RH, respectively.
PMCID: PMC380740  PMID: 4631439
11.  R Factor-Mediated Antibiotic Resistance in Serratia marcescens 
Nineteen of 39 multiresistant strains of Serratia marcescens isolated from clinical sources transferred antibiotic resistance to Escherichia coli or Klebsiella pneumoniae recipients. Marcesins and/or phage prevented effective resistance transfer to E. coli and attempts to select marcescin-resistant mutants of the E. coli recipient strain were unsuccessful. Transfer of resistance was demonstrated for all drugs tested except nalidixic acid. Approximately 90% of donors resistant to tobramycin, ampicillin, or carbenicillin transferred resistance to these drugs. High levels of transferred resistance (minimal inhibitory concentration, >2,500 μg/ml) were demonstrated particularly for ampicillin, carbenicillin, and kanamycin. Transmissibility of Serratia R factors was greatest between isogeneic strains of E. coli K-12. Comparative rates of spontaneous loss of R factor-mediated resistance indicated that Serratia R factors are less stable in E. coli and K. pneumoniae transcipients than in the indigenous hosts.
PMCID: PMC429700  PMID: 791085
12.  Prodigiosin-Producing Bacteria from Marine Sources1 
Applied Microbiology  1964;12(1):13-17.
Two aerobic, gramnegative, red-pigmented, rod-shaped bacteria were compared morphologically and physiologically with Serratia species, which they resembled superficially. The pigment produced by the marine isolates was shown to be similar to prodigiosin, the red pigment of S. marcescens. The isolates had a single polar flagellum, were oxidative, and did not produce acetoin from glucose or reduce nitrates, which made them distinct from both S. marcescens and S. marinorubra. The latter conformed well to the descriptions of S. marcescens in Bergey's Manual. The marine isolates displayed an absolute growth requirement for sea water or its equivalent. The growth requirement for sea water was replaced by sea-water levels of sodium, potassium, and magnesium chloride. Pigment was produced only when this salt mixture was further supplemented with calcium chloride. Neither sea water nor a high salt level was required for growth or prodigiosin synthesis by the Serratia species examined.
PMCID: PMC1058056  PMID: 14106932
13.  A novel medium for the enhanced cell growth and production of prodigiosin from Serratia marcescens isolated from soil 
BMC Microbiology  2004;4:11.
Prodigiosin produced by Serratia marcescens is a promising drug owing to its reported characteristics of having antifungal, immunosuppressive and antiproliferative activity. From an industrial point of view the necessity to obtain a suitable medium to simultaneously enhance the growth of Serratia marcescens and the pigment production was the aim of this work. The usage of individual fatty acid as substrate in industries would be cost-effective in the long run and this paved the way for us to try the effect of different fatty acid-containing seeds and oils of peanut, sesame and coconut as source of substrate.
The addition of sugars only showed slight enhancement of prodigiosin production in nutrient broth but not in fatty acid containing seed medium. The powdered peanut broth had supported better growth of Serratia marcescens and higher yield of prodigiosin when compared with the existing nutrient broth and peptone glycerol broth. A block in prodigiosin production was seen above 30°C in nutrient broth, but the fatty acid seed medium used by us supported prodigiosin production upto 42°C though the yields were lower than what was obtained at 28°C. From the results, the fatty acid form of carbon source has a role to play in enhanced cell growth and prodigiosin production.
We conclude by reporting that the powdered and sieved peanut seed of different quality grades were consistent in yielding a fourty fold increase in prodigiosin production over the existing media. A literature survey on the composition of the different media components in nutrient broth, peptone glycerol broth and the fatty acid containing seeds and oils enabled us to propose that the saturated form of fatty acid has a role to play in enhanced cell growth and prodigiosin production. This work has also enabled us to report that the temperature related block of prodigiosin biosynthesis varies with different media and the powdered peanut broth supports prodigiosin production at higher temperatures. The medium suggested in this work is best suitable from an industrial point of view in being economically feasible, in terms of the higher prodigiosin yield and the extraction of prodigiosin described in this paper is simple with minimal wastage.
PMCID: PMC404375  PMID: 15113456
14.  Sulfamethoxazole-Trimethoprim-Polymyxin Therapy of Serious Multiply Drug-Resistant Serratia Infections 
Nonpigmented multiply drug-resistant Serratia marcescens caused an extensive outbreak of infection at the Nashville Veterans Administration Hospital. Isolates were of one serotype resistant to all currently available antimicrobial agents for therapy of systemic infections except for occasional susceptibility to chloramphenicol and kanamycin. Frequently strains were susceptible to nalidixic acid, and all were susceptible to amikacin (BB-K8). Drug-resistant strains caused 130 infections, 12 bacteremias, and 7 infection-associated deaths. Combinations of antimicrobial agents were evaluated for synergism against Serratia strains from infected patients. “Checkerboard” isobolograms indicated in vitro static synergism between sulfamethoxazole, trimethoprim, and polymyxin (STP). Killing curves using clinically achievable concentrations of STP verified the bactericidal effect of STP against these strains. In a daily dosage of 1,600 mg of sulfamethoxazole and 320 mg of trimethoprim orally in combination with 100 to 300 mg of colistimethate parenterally, serum cidal levels at 1:8 or greater were achieved in five of six patients. Clinical improvement or microbiological cure was effected in four of six patients. STP may be potentially useful for selected Serratia infections for which single agents are unavailable or ineffective.
PMCID: PMC429504  PMID: 178273
15.  Spheroplast induction in clinical isolates of Serratia marcescens in the presence of Ca2+ or Mg2+. 
Journal of Clinical Microbiology  1987;25(11):2154-2158.
Serratia marcescens was easily induced to form spheroplasts by beta-lactam antibiotics in the presence of Ca2+ or Mg2+ without an osmotic stabilizer such as sucrose. The spheroplasts grew in volume, although they could not divide. They were stable for more than 10 h at 37 degrees C in a medium containing a high concentration of antibiotic, and they had the ability to revert to the original bacillary form. Ca2+ was more effective in spheroplast induction than Mg2+. The effect was proportional to the concentration of cations. In 40% of 180 clinical isolates of S. marcescens, more than 40% of the original bacterial cells were induced to form spheroplasts by ceftizoxime in a medium supplemented with 40 mM Ca2+. A high spheroplast induction rate was observed even in medium with 10 mM Ca2+. Few isolates that were supersusceptible to ceftizoxime (MIC, less than 0.2 microgram/ml) were induced to form spheroplasts at a high rate. No difference in spheroplast induction rate or extent between antibiotic-resistant strains and relatively susceptible strains (MIC, greater than 0.2 microgram/ml) was found. The serotype of S. marcescens had no effect on the spheroplast induction rate. Monocations (Na+ and K+) had little effect on spheroplast induction.
PMCID: PMC269431  PMID: 3320083
16.  Comprehensive evaluation of ciprofloxacin-aminoglycoside combinations against Enterobacteriaceae and Pseudomonas aeruginosa strains. 
The in vitro activities of antibiotic combinations containing ciprofloxacin and either gentamicin, sisomicin, netilmicin, amikacin, or tobramycin were evaluated by checkerboard assay (agar dilution method). A total of 220 strains of Enterobacteriaceae and Pseudomonas aeruginosa (11 species, 20 strains each) were tested. Synergistic or antagonistic effects were observed in less than 1% of the tests performed; they appeared to represent method-dependent fluctuations rather than true antibiotic interactions. No significant differences among the five aminoglycosides tested were seen. Time-kill experiments performed with three representative strains of Escherichia coli and Serratia marcescens showed additive combination effects with respect to the kill rates and inhibition of bacterial regrowth. Exposure of Serratia strains to either ciprofloxacin or gentamicin before the addition of the second drug had little influence on the combination effects observed. No antagonistic drug interactions were seen in vivo when combination therapy with ciprofloxacin and gentamicin was evaluated in a model of E. coli thigh muscle infection in neutropenic mice. Comparable therapeutic effects were obtained, regardless of whether the two compounds were administered simultaneously or sequentially at 1- or 2-h intervals.
PMCID: PMC176353  PMID: 2936301
17.  Serratia pneumonia presenting as hemoptysis in a patient with sarcoidosis: a case report 
Serratia marcescens is a Gram-negative bacillus which belongs to the family Enterobacteriaceae. It is a facultative anaerobe and produces red pigment at room temperature. It naturally occurs in soil and water as well as the intestines, and it is responsible for nosocomial infections. There have been few reports about community acquired pneumonia of Serratia.
Case presentation
This report presents a 37-year-old man with hemoptysis, fever, and shortness of breath. The clinical and laboratory examinations revealed that the patient had pseudohemoptysis due to S. marcescens pneumonia, on an immunocompromised pattern, because of the coexistence of sarcoidosis (stage 1).
Appropriate antibiotic therapy for Serratia was administered, and the patient’s symptoms regressed. The patient is healthy and asymptomatic after 1-year follow-up. To the best of the authors’ knowledge, this is the first reported case of a pseudohemoptysis in a patient with pulmonary sarcoidosis.
PMCID: PMC3177592  PMID: 21941452
Serratia marcescens; pseudohemoptysis; pulmonary sarcoidosis
18.  Effect of Water Vapor on Lyophilized Serratia marcescens and Escherichia coli 
Applied Microbiology  1967;15(6):1299-1302.
Dried Serratia marcescens ATTC 14014 and Escherichia coli ATTC 4157 cells were exposed to various partial pressures of purified water vapor. The colony-forming ability of the S. marcescens was unimpaired when the dried organisms were stored in water-vapor atmosphere such that P/P0 < 0.55 or P/P0 = 1.0 (where P is the pressure of the water vapor in contact with the organisms, and P0 is vapor pressure of pure water at 25 C). During storage under water-vapor atmospheres with P/P0 between 0.6 and 1.0, the colony-forming ability of the dried S. marcescens was destroyed. The inactivation by water vapor followed the expression — ln N/N0 = Kt1/2, where N0 and N are the number of viable organisms before and after exposure, respectively, t is time, and K is a pseudo constant which is dependent upon the partial pressure of the water vapor at 25 C. Similar results were obtained with dried E. coli. The addition of solutes to the suspending media before freeze-drying was found to influence the stability of the organisms during exposure to water vapor.
PMCID: PMC547187  PMID: 16349738
19.  Survival of Microorganisms in Laundered Polyester-Cotton Sheeting1 
Applied Microbiology  1973;25(3):431-435.
The effects of wash-water temperature, cold-water or regular detergent, wash-cycle design, drying, and drying temperature on survival of four microorganisms on polyester-cotton sheeting were examined. Escherichia coli T3 bacteriophage survived washing at 24, 35, 46, and 57 C, but not at 68 C. Serratia marcescens survived only the lowest three wash temperatures. Levels of residual Staphylococcus aureus were diminished at the highest two wash temperatures, but survival was substantial even at 68 C. Counts of Bacillus stearothermophilus spores were not altered appreciably by wash temperature. Type of detergent had no practical effect on observed counts. The regular wash cycle was significantly more efficient in removal of microorganisms than the permanent-press cycle. Counts, especially of the bacteriophage and the gramnegative bacterium, were decreased by drying; after drying, the effects of wash-water temperature on S. aureus and B. stearothermophilus were not significantly different. Microorganisms were transferred from inoculated to sterilized sheeting during laundering. The public health significance of these observations is discussed.
PMCID: PMC380823  PMID: 4572894
20.  Formation and Purification of Serratia marcescens Arylsulfatase 
The effects of culture conditions on arylsulfatase production by six strains of the genus Serratia were studied. Synthesis of arylsulfatases in all six strains was repressed in media with inorganic sulfate or methionine as the sole source of sulfur and derepressed by the addition of tyramine. Serratia marcescens IFO 3046 grew most rapidly and produced a high level of arylsulfatase when cultured on mannitol with inorganic sulfate and tyramine. The derepressed synthesis of arylsulfatase in S. marcescens was not subject to strong catabolite repression. The molecular weight of purified arylsulfatase was determined to be between 46,000 and 49,000. Arylsulfatase from S. marcescens differed in Km and Vmax values, substrate specificities, fluoride inhibition, and electrophoretic mobility from the enzyme from K. aerogenes, but had the same molecular weight as the latter.
PMCID: PMC291424  PMID: 16345546
21.  Numerical analysis of SDS-PAGE protein patterns of Serratia marcescens: a comparison with other typing methods. 
Epidemiology and Infection  1990;105(1):107-117.
Twenty-five cultures comprising 18 clinical isolates of Serratia marcescens from two hospitals, the type strain of S. marcescens, two reference strains of S. marinorubra, the type or a reference strain of three other Serratia species and a reference strain of undetermined species, were characterized by one-dimensional sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) of whole-cell proteins. The protein patterns were highly reproducible and were used as the basis of a numerical analysis which divided the clinical isolates into eight protein types. Comparison with O-serotyping indicated that the level of discrimination by SDS-PAGE was similar. As with O-serotyping, a secondary scheme, such as phage typing, is necessary to differentiate strains of the same protein type. We conclude that high-resolution SDS-PAGE of proteins provides an effective adjunct to other methods for typing isolates of S. marcescens.
PMCID: PMC2271800  PMID: 2200696
22.  Mutational Upregulation of a Resistance-Nodulation-Cell Division-Type Multidrug Efflux Pump, SdeAB, upon Exposure to a Biocide, Cetylpyridinium Chloride, and Antibiotic Resistance in Serratia marcescens▿  
Antimicrobial Agents and Chemotherapy  2009;53(12):5230-5235.
Serratia marcescens is an important opportunistic pathogen in hospitals, where quaternary ammonium compounds are often used for disinfection. The aim of this study is to elucidate the effect of a biocide on the emergence of biocide- and antibiotic-resistant mutants and to characterize the molecular mechanism of biocide resistance in Serratia marcescens. A quaternary ammonium compound-resistant strain, CRes01, was selected by exposing a wild-type strain of S. marcescens to cetylpyridinium chloride. The CRes01 cells exhibited 2- to 16-fold more resistance than the wild-type cells to biocides and antibiotics, including cetylpyridinium chloride, benzalkonium chloride, chlorhexidine gluconate, fluoroquinolones, tetracycline, and chloramphenicol, and showed increased susceptibilities to β-lactam antibiotics and N-dodecylpyridinium iodide. Mutant cells accumulated lower levels of norfloxacin than the parent cells in an energized state but not in a de-energized state, suggesting that the strain produced a multidrug efflux pump(s). To verify this assumption, we knocked out a putative efflux pump gene, sdeAB, in CRes01 and found that the knockout restored susceptibility to most quaternary ammonium compounds and antibiotics, to which the CRes01 strain showed resistance. On the basis of these and other results, we concluded that S. marcescens gains resistance to both biocides and antibiotics by expressing the SdeAB efflux pump upon exposure to cetylpyridinium chloride.
PMCID: PMC2786342  PMID: 19752278
23.  Preservation of Serratia marcescens by High-Vacuum Lyophilization 
Applied Microbiology  1966;14(4):561-567.
Water-washed Serratia marcescens (ATCC strain 14041) cells were lyophilized in an all-glass system capable of evacuation to pressures of less than 5 × 10-6 torr. Lyophilization at the lowest pressures resulted in 50 to 65% survival for unstabilized washed organisms compared with 10 to 20% when the cells were lyophilized at pressures of about 2.5 × 10-2 torr. At the latter pressures, 45 to 65% survival was obtained when NaCl or Naylor-Smith stabilizer was added to the cell suspensions before lyophilization. However, the stabilizers failed to increase significantly the levels of survival compared with water suspension when cells were lyophilized at pressures less than 10-5 torr. The high survival rates obtained by the high-vacuum technique may be attributed to the reduction of traces of molecular oxygen which has been reported to be destructive of the dried bacteria. Survival of unstabilized dried S. marcescens after 1-day storage increased markedly with decreasing sealing pressure. Under the highest vacuum attained, survival of the dried bacteria was not impaired by storage for up to 1 month at Dry Ice temperatures; at higher temperatures, viability losses occurred. Exposure of the dried unstabilized bacteria to dry air resulted in rapid viability loss. The inactivation could be stopped almost immediately by evacuation to pressures of less than 10-5 torr, but the evacuation failed to reverse the viability losses that occurred during exposure.
PMCID: PMC546782  PMID: 5332950
24.  Use of colistin and sorbitol for better isolation of Serratia marcescens in clinical samples. 
Epidemiology and Infection  1988;101(2):315-320.
A comparison was made of different culture media and procedures for detection of Serratia marcescens from faecal, pharyngeal and ocular swabs collected from 213 neonates. MacConkey agar and MacConkey agar with sorbitol (1%) and/or colistin (200 i.u./ml) were used both for primary isolation and after enrichment using Mossel Enterobacteriaceae broth with colistin (200 i.u./ml). The use of MacConkey agar supplemented with colistin for primary isolation improved considerably the isolation rate of S. marcescens from faecal swabs but not from pharyngeal swabs; the number of ocular isolations were insufficient to demonstrate differences between procedures. Moreover the enrichment procedures consistently increased the number of S. marcescens isolates especially from pharyngeal and ocular swabs. Use of sorbitol made detection of S. marcescens from clinical specimens easier and time- and cost-efficient.
PMCID: PMC2249382  PMID: 3053219
25.  Outbreak of a Cluster with Epidemic Behavior Due to Serratia marcescens after Colistin Administration in a Hospital Setting 
Journal of Clinical Microbiology  2013;51(7):2295-2302.
Serratia marcescens causes health care-associated infections with important morbidity and mortality. Particularly, outbreaks produced by multidrug-resistant isolates of this species, which is already naturally resistant to several antibiotics, including colistin, are usually described with high rates of fatal outcomes throughout the world. Thus, it is important to survey factors associated with increasing frequency and/or emergence of multidrug-resistant S. marcescens nosocomial infections. We report the investigation and control of an outbreak with 40% mortality due to multidrug-resistant S. marcescens infections that happened from November 2007 to April 2008 after treatment with colistin for Acinetobacter baumannii meningitis was started at hospital H1 in 2005. Since that year, the epidemiological pattern of frequently recovered species has changed, with an increase of S. marcescens and Proteus mirabilis infections in 2006 in concordance with a significant decrease of the numbers of P. aeruginosa and A. baumannii isolates. A single pulsed-field gel electrophoresis (PFGE) cluster of S. marcescens isolates was identified during the outbreak. When this cluster was compared with S. marcescens strains (n = 21) from 10 other hospitals (1997 to 2010), it was also identified in both sporadic and outbreak isolates circulating in 4 hospitals in Argentina. In132::ISCR1::blaCTX-M-2 was associated with the multidrug-resistant cluster with epidemic behavior when isolated from outbreaks. Standard infection control interventions interrupted transmission of this cluster even when treatment with colistin continued in several wards of hospital H1 until now. Optimizing use of colistin should be achieved simultaneously with improved infection control to prevent the emergence of species naturally resistant to colistin, such as S. marcescens and P. mirabilis.
PMCID: PMC3697717  PMID: 23698525

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