Non-pigmented Strain Of Serratia Marcescens Research Articles

Injection site abscess in an immunocompromised patient caused by non-pigmented strain of Serratia marcescens

Injection site abscess in an immunocompromised patient caused by non-pigmented strain of Serratia marcescens - IJMR- Print ISSN No: - 2394-546X Online ISSN No:- 2394-5478 Article DOI No:- 10.18231/j.ijmr.2019.040, Indian Journal of Microbiology Research-Indian J Microbiol Res

Ozone Sensitivity and Catalase Activity in Pigmented and Non-Pigmented Strains of Serratia Marcescens.

Background:Ozone exposure rapidly leads to bacterial death, making ozone an effective disinfectant in food industry and health care arena. However, microbial defenses may moderate this effect and play a role in the effective use of oxidizing agents for disinfection. Serratia marcescens is an opportunistic pathogen, expressing genes differentially during infection of a human host. A better understanding of regulatory systems that control expression of Serratia’s virulence genes and defenses is therefore valuable.Objective:Here, we investigated the role of pigmentation and catalase in Serratia marcescens on survival to ozone exposure.Method:Pigmented and non-pigmented strains of Serratia marcescens were cultured to exponential or stationary phase and exposed to 5 ppm of gaseous ozone for 2.5 – 10 minutes. Survival was calculated via plate counts. Catalase activity was measured photometrically and tolerance to hydrogen peroxide was assayed by disk-diffusion.Results:Exposure of S. marcescens to 5 ppm gaseous ozone kills > 90% of cells within 10 minutes in a time and concentration-dependent manner. Although pigmented Serratia (grown at 28°C) survived ozonation better than unpigmented Serratia (grown at 35°C), non-pigmented mutant strains of Serratia had similar ozone survival rates, catalase activity and H2O2 tolerance as wild type strains. Rather, ozone survival and catalase activity were elevated in 6 hour cultures compared to 48 hour cultures.Conclusion:Our studies did not bear out a role for prodigiosin in ozone survival. Rather, induction of oxidative stress responses during exponential growth increased both catalase activity and ozone survival in both pigmented and unpigmented S. marcescens.

Extracellular Vesicle Formation and Biosurfactant Production by Serratia marcescens

Summary: Pigmented and non-pigmented strains of Serratia marcescens produced extracellular vesicles and had wetting activity when grown at 30°C but not at 37°C. Light microscopy showed that the red pigment was present in vesicles and intracellular granules. Electron microscopy revealed the presence of vesicles surrounded by the bacterial membrane. Three lipids having the wetting activity, W1, W2 and W3, were isolated by thin-layer chromatography of lipids from different strains of S. marcescens. Dispersions of the isolated wetting agents had small contact angles on a polystyrene surface and the ability to lower surface tension. Wetting agent W1 was the aminolipid serratamolide. Wetting agents W2 and W3 were also aminolipids but were shown to be different from serratamolide by chemical analyses. Wetting agent and prodigiosin (in a pigmented strain) were the main lipids of isolated vesicles.

Decrease in respiration activity related to prodigiosin synthesis in Serratia marcescens.

Variation in the cell respiration rate of pigmented and nonpigmented strains of Serratia marcescens was exhibited. The respiration rate of a pigmented strain decreased earlier than that of nonpigmented strains in the late exponential or early stationary phase. However when prodigiosin synthesis was not induced by exchange of carbon sources in the medium, the decrease in the respiration rate of the pigmented strain was the same as that of nonpigmented strains. Measurement of the oxygen consumption rate in the sonicated cell membrane by adding NADH solution showed that the rate in the pigmented strain was lower than that in nonpigmented strains. Furthermore, the cell membrane of prodigiosin-induced organisms was more sensitive to respiration inhibitors than that of pigment-noninduced organisms of the pigmented strain. These results showed that the respiration activity was decreased by prodigiosin synthesis in S. marcescens.

Insect pathogenic properties of Serratia marcescens: phage-resistant mutants with a decreased resistance to Cecropia immunity and a decreased virulence to Drosophila.

A non-pigmented strain of Serratia marcescens (Db10) was isolated from moribund Drosophila flies. From this strain were isolated spontaneous mutants resistant to streptomycin (Db11) and nalidixic acid (Db12). Mutant Db11 was used for the isolation of two phages, phi J and phi K, which grew on Db10, Db11 and Db12, but not on three reference strains of S. marcescens. Mutant Db11 was demonstrated to fulfil koch's postulates. Strain Db10 and its antibiotic-resistant derivatives were lethal to Drosophila whether given in the food or by injection. Evidence for toxin(s) was found only in sterile supernatants from 7 d cultures. Such extracts contained proteolytic activity and inactivated the antibacterial activity in immune haemolymph from Cecropia. Phages phi J and phi K were used to isolate phage-resistant mutants of Db11. Three such mutants and their parental strain were investigated for their susceptibility to immune haemolymph from Cecropia. The parental strain was resistant to incubation with 90% haemolymph for 2 h at 37 degrees C; all phage-resistant mutants were susceptible to the immune haemolymph with "killing times" (i.e. the time required to kill 90% of the viable cells) ranging from 15 to 55 min. When the same strains were compared for their virulence to Drosophila, the phage-resistant mutants had significantly reduced virulence. It is concluded that resistance to insect immunity plays an important role in the overall pathogenicity of S. marcescens.

763 ERADICATION OF SERRATIA MARCESCENS FROM AN NICU

In a 10 month period 29 infants in an NICU were infected with a highly resistant non-pigmented strain of Serratia marcescens. The organism was cultured from stool,umbilicus,catheter tip,eye, groin,blood, and at autopsy from CSF,lung,and spleen. After one death from Serratia sepsis (+ blood culture) 5 infants in the same room developed positive cultures in nose, urine, stool and cord. Positive cultures for the same strain were found retrospectively in 8 infants during the preceding 6 months, none of whom demonstrated clinical illness. As Serratia is commonly water-borne,environmental survey was carried out. Blood pressure machines,EKG paste, and urine refractometers were negative. The epidemic strain was recovered from an incubator humidifier. An aseptic protocol for cleaning incubators was adhered to and the room with infected infants was closed and cleaned. Despite these measures 7 additional infants became infected. The Serratia was finally eradicated by placing all infants on gown and glove pre-cautions, admitting new infants to clean rooms only, and by segregating older infants. Although 10 older infants in the isolated group developed Serratia infections in the following month, no new infant became colonized or infected. Two weeks following the discharge of the last infected infant Serratia was recovered from the umbilicus of a transported infant. This infant's strain differed in antibiotic sensitivities from the previous strain. Adherence to environmental control prevented its spread.

The inhibitory effect of the artificial electron donor system, phenazine methosulfate‐ascorbate, on bacterial transport mechanisms

The artificial electron donor system, phenazine methosulfate (PMS)-ascorbate, inhibited active transort of solutes in Pseudomonas aeruginosa irrespective of whether the active transport systems were shock sensitive or shock resistant. N,N,N',N'-tetramethylphenylenediamine could be substituted for PMS but a higher concentration was required. PMS-ascorbate also inhibited active transport in several other bacterial species with the exception of Escherichia coli and of a nonpigmented strain of Serratia marcescens. PMS-ascorbate previously has been shown to energize active transport in isolated membrane vesicles, even those prepared from the same bacterial species in whose intact cells active transport was inhibited. The apparent Km of glucose active transport in untreated cells of P. aeruginosa was 40 micron while the Km of glucose transport in cells incubated with PMS-ascorbate was 25 mM, and PMS-ascorbate had no effect on efflux of accumulated glucose. These results strongly suggested that facilitated diffusion resulted upon exposure of the cells to PMS- ascorbate. Thus, PMS-ascorbate appeared to have an uncoupler-like effect on cells of P. aeruginosa. The experimental data also pointed out that there are fundamental differences between the response of intact cells and membrane vesicles to exogenous electron donors.

Amoxycillin and Ampicillin

In vitro antibacterial activities of ampicillin and amoxycillin were compared against pigmented and non-pigmented strains of Serratia marcescens. Ampicillin appeared more effective than amoxycillin; three-fourths of all strains consistently exhibited an ampicillin minimum inhibitory concentration (MIC) of at least one tube less than that recorded for amoxycillin. Complete cross resistance was not observed as has previously been inferred. Further, greater bactericidal activity was demonstrated with ampicillin; minimum bactericidal concentrations (MBC) were either the same as or one tube greater than the MIC. MBC's for amoxycillin, however, were significantly higher; often four to five times greater than the MIC. Ampicillin exhibited greater bactericidal activity as inferred from differences observed in the biological lesions induced, as recorded through observations by scanning electron microscopy (SEM). Spheroplasts were the predominant morphological alteration induced by ampicillin. In contrast, only filament formation, which demonstrated a degree of reversibility, was induced by amoxycillin.

Endocarditis From Serratia marcescens

Despite the increasing frequency of nosocomial infections due to nonpigmented strains ofSerratia marcescens, infective endocarditis from this organism is rare. This communication adds three such cases to the previously reported four. Five of the seven patients succumbed to infection. Some predisposing factor could be identified in all seven. Therapy was extremely difficult because of resistance to antibiotics and persistence of infection despite the use of appropriate chemotherapeutic agents, including nalidixic acid intravenously, used unsuccessfully in two patients. The difficulty in eradicating this infection once it has become established on a prosthetic valve is evident. The possibility that intravenous foreign bodies are a source of infection must be considered.