Viable but nonrecoverable stage of <i>Salmonella enteritidis</i> in aquatic systems

Roszak, D. B.; Grimes, D. Jay; Colwell, Rita R.

doi:10.1139/m84-049

Cited by 390 publications

(231 citation statements)

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“…It may be inferred, therefore, that the unsupplemented albumen induces a quiescent state in salmonella. This phenomenon was noted by Rozak, Grimes and Colwell [23] who worked on water contaminated naturally with this organism. This novel proposal may be linked with the observation [24] that the alkalinity (pH 9-6) of the albumen induces a marked change in the characteristics, e.g.…”

Section: Discussionmentioning

confidence: 70%

Persistence of contamination of hens' egg albumen in vitro with Salmonella serotypes

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1992

Epidemiol. Infect.

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SUMMARYA study was made of the persistence of different Salmonella serotypes in hens' egg albumen in vitro at 4, 20 and 30 °C. The majority of serotypes remained viable but did not increase in numbers at 20 and 30 °C for 42 days. At 4 °C many of the serotypes died out.The addition of ferric ammonium citrate on the 42nd day of incubation induced multiplication of organisms incubated at 20 and 30 °C, but not at 4 °C. The pH and glucose concentration of the albumen diminished only when heavy growth occurred.Salmonella enteritidis remained viable on the air cell membrane in vitro for 17 days at 4, 20 and 30 °C. Thirty percent of the organisms also remained motile in albumen for 42 days at 25 °C and up to 5% of the cells remained motile for up to 20 days at 4 °C.

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Section: Discussionmentioning

confidence: 70%

Persistence of contamination of hens' egg albumen in vitro with Salmonella serotypes

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1992

Epidemiol. Infect.

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“…Escherichia coli O157:H Ϫ strain E 32511/HSC became nonculturable in sterilized distilled water microcosms at 4°C in about 21 days (24). Roszak et al reported that Salmonella serovar Enteritidis 13-1BB entered the nonculturable state within 48 h when it was incubated in Potomac River water (39). The clinical isolate Vibrio cholerae ATCC 14035 was found to enter the VBNC state in 6 to 9 days in Chesapeake Bay water at 4 to 6°C (51).…”

Section: Discussionmentioning

confidence: 99%

Retention of Virulence in a Viable but Nonculturable Edwardsiella tarda Isolate

Chen

Zhang

et al. 2007

Appl Environ Microbiol

100

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Edwardsiella tarda is pathogen of fish and other animals. The aim of this study was to investigate the viable but nonculturable (VBNC) state and virulence retention of this bacterium. Edwardsiella tarda CW7 was cultured in sterilized aged seawater at 4°C. Total cell counts remained constant throughout the 28-day period by acridine orange direct counting, while plate counts declined to undetectable levels (<0.1 CFU/ml) within 28 days by plate counting. The direct viable counts, on the other hand, declined to ca. 10 9 CFU/ml active cells and remained fairly constant at this level by direct viable counting. These results indicated that a large population of cells existed in a viable but nonculturable state. VBNC E. tarda CW7 could resuscitate in experimental chick embryos and in the presence of nutrition with a temperature upshift. The resuscitative times were 6 days and 8 days, respectively. The morphological changes of VBNC, normal, and resuscitative E. tarda CW7 cells were studied with a scanning electron microscope. The results showed that when the cells entered into the VBNC state, they gradually changed in shape from short rods to coccoid and decreased in size, but the resuscitative cells did not show any obvious differences from the normal cells. The VBNC and the resuscitative E. tarda CW7 cells were intraperitoneally inoculated into turbot separately, and the fish inoculated with the resuscitative cells died within 7 days, which suggested that VBNC E. tarda CW7 might retain pathogenicity.Edwardsiella tarda, an enteric gram-negative bacterium of the Enterobacteriaceae, is the causative agent of the systemic disease edwardsiellosis in freshwater and marine fish worldwide. The bacterium causes septicemia with extensive skin lesions and affects internal organs, such as the liver, kidney, spleen, and muscle (33, 52). It has been isolated from a variety of animals, including fish, birds, mammals, and reptiles (12,27,31,46,47), and environmental water (32, 50). Several potential virulence properties have been suggested to contribute to the pathogenesis of E. tarda, namely, the production of dermatotoxin (45) and hemolysin (14) and the ability to resist phagocyte-mediated destruction and to invade epithelial cells (19,22,43). However, little is known about the pathogenic mechanism of E. tarda, and the causes of disease occurrence are still elusive.Many bacteria have developed strategies for metamorphosis into more or less sophisticated survival forms in response to harsh environmental conditions, such as a temperature change, high salinity, or nutrient deprivation (4, 5). The formation of viable but nonculturable (VBNC) cells of bacteria has been proposed as a strategy to survive adverse conditions (10). The first clear evidence of the existence of the VBNC state in pathogens was provided by Xu et al. It has been demonstrated that VBNC cells are active in metabolism (16,20,53) and are able to recover from their dormant state, becoming metabolically active and fully culturable (26,40,48). Some pathogens in the VBNC ...

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“…The addition of nutrients, usually a small amount of yeast extract, is generally required (61). This direct viable count (DVC) method has been applied for detection of viable Vibrio vulnificus (91,105), estimation of viable counts of several gramnegative bacteria in an aquatic environment (15,20,28,29,112,115,127,128,129,150), and detection of viable bacteria in biofilms (151,152). In general, viable counts determined by the DVC method are considerably higher than the corresponding plate counts, which implies the existence of viable but nonculturable bacteria.…”

Section: Flow Cytometrymentioning

confidence: 99%