title: Fate of pathogenic bacteria in microcosms mimicking human body sites.
abstract: During the infectious process, pathogens may reach anatomical sites where they are exposed to substances interfering with their growth. These substances can include molecules produced by the host, and his resident microbial population, as well as exogenous antibacterial drugs. Suboptimal concentrations of inhibitory molecules and stress conditions found in vivo (high or low temperatures, lack of oxygen, extreme pH) might induce in bacteria the activation of survival mechanisms blocking their division capability but allowing them to stay alive. These "dormant" bacteria can be reactivated in particular circumstances and would be able to express their virulence traits. In this study, it was evaluated the effect of some environmental conditions, such as optimal and suboptimal temperatures, direct light and antibiotic sub-inhibitory concentrations doses of antibiotic, on the human pathogens Escherichia coli and Enterococcus faecalis when incubated in fluids accumulated in the body of patients with different pathologies. It is shown that inoculation in a number of accumulated body fluids and the presence of gentamicin, reliable conditions encountered during pathological states, induce stress-responding strategies enabling bacteria to persist in microcosms mimicking the human body. Significant differences were detected in Gram-negative and Gram-positive species with E. faecalis surviving, as starved or viable but non-culturable forms, in any microcosm and condition tested and E. coli activating a viable but non-culturable state only in some clinical samples. The persistence of bacteria under these conditions, being non-culturable, might explain some recurrent infections without isolation of the causative agent after application of the standard microbiological methods.
authors: Dipartimento di Patologia e Diagnostica, Sezione di Microbiologia, Università di Verona, Strada Le Grazie 8, 37134, Verona, Italy.
authors: Francesco
authors: F
authors: Castellani
authors: Valentina
authors: V
authors: Ghidini
authors: Maria Carla
authors: MC
authors: Tafi
authors: Marzia
authors: M
authors: Boaretti
authors: Maria M
authors: MM
authors: Lleo
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001202:Ascitic Fluid / Q000737:chemistry / Q000382:microbiology*; D001424:Bacterial Infections / Q000382:microbiology*; D013293:Enterococcus faecalis / Q000187:drug effects / Q000502:physiology*; D004926:Escherichia coli / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D050296:Microbial Viability; D013582:Synovial Fluid / Q000737:chemistry / Q000382:microbiology*
chemical_list: D000900:Anti-Bacterial Agents
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