Active but nonculturable cells of Salmonella enterica serovar Typhimurium do not infect or colonize mice

• Published in: Microbiology (Society for General Microbiology) 2002-09, Vol.148 (9), p.2717-2726
• Main Authors: Smith, Rebecca J, Newton, Angela T, Harwood, Colin R, Barer, Michael R
• Format: Article
• Language: English
• Subjects: Administration, Oral; Animals; Anti-Bacterial Agents - pharmacology; Bacteriology; Biological and medical sciences; Chloramphenicol - pharmacology; Female; Fundamental and applied biological sciences. Psychology; Injections, Intraperitoneal; Lethal Dose 50; Mice; Mice, Inbred BALB C; Microbiology; Pathogenicity, virulence, toxins, bacteriocins, pyrogens, host-bacteria relations, miscellaneous strains; Salmonella enterica; Salmonella Infections, Animal - microbiology; Salmonella typhimurium - drug effects; Salmonella typhimurium - pathogenicity; Salmonella typhimurium - physiology; Virulence
• ISSN: 1350-0872; 1465-2080
• DOI: 10.1099/00221287-148-9-2717

Department of Microbiology and Immunology, Medical Sciences Building, PO Box 138, University Road, Leicester LE1 9HN, UK 1 Department of Microbiology and Immunology, University of Newcastle, Newcastle upon Tyne NE2 4HH, UK 2 Author for correspondence: Rebecca J. Smith. Tel: [phone]. Fax: [phone]. e-mail: rjs29{at}le.ac.uk The possibility that nonculturable cells of a normally culturable bacterial pathogen may constitute a source or reservoir for infective disease was investigated. In multiple experiments and with careful attention to the statistical limitations of the assays used, Salmonella enterica serovar Typhimurium cells rendered nonculturable by carbon and nitrogen stress in the presence of chloramphenicol were administered orally and intraperitoneally to over 300 female BALB/c mice. Neither infection nor colonization was detected in these studies, even when active but nonculturable (ABNC) cells, as defined by the Kogure cell elongation assay, were present in the inoculum. Doses of ABNC cells exceeding the oral and intraperitoneal LD 50 values by 3·5 and 2 orders of magnitude, respectively, were administered. It was concluded that ABNC cells of the salmonella strains used could not be considered potentially infective and that their detection in samples from material being evaluated as a potential source or reservoir of infection by the Kogure test does not specifically represent an infective hazard. Keywords: viable but nonculturable, viability testing, infectivity Abbreviations: ABNC, active but nonculturable; CCN, chloramphenicol-treated carbon/nitrogen-stressed; MCCN, minimally stressed CCN; i.p., intraperitoneal(ly); MPN, most probable number; TCC, total cell count; VBNC, viable but nonculturable