Resuscitation of ‘non-culturable’ cells from aged cultures of Campylobacter jejuni

Abstract

When stationary phase batch cultures of Csmpylobacter jejuni were stored in sealed flasks under static conditions, viable numbers declined from 2 x lo9 c.f.u. ml'' to around 103-106 c.f.u. ml'l within 4-6 weeks. When the aged cultures were sparged with a microaerobic gas mixture, there was a rapid increase in viable numbers accompanied by a change from predominantly coccoid t o vibrioid morphology. The most probable number (MPN) technique was used to distinguish resuscitation of injured or dormant cells from multiplication of residual viable cells. MPN estimates using fresh Brucella broth containing 0.2 O/ O mucin revealed that plate counts underestimated the true viable count by up to 23-fold. The experiments clearly demonstrated that a proportion of surviving cells in aged cultures were in an injured or latent state that prevented growth on agar plates. It is possible that the size of this fraction is greater than was demonstrated and that much higher recoveries would be obtained under other recovery conditions. Nevertheless, from presently available evidence, it must be concluded that the size of the latent fraction is quite small and that most of the increase in count that occurs on regassing a spent culture comes from multiplication of residual viable cells.

The β-Defensin Gallinacin-6 Is Expressed in the Chicken Digestive Tract and Has Antimicrobial Activity against Food-Borne Pathogens

“…The differences between both types of assays can be explained in part by the greater stringency of the broth microdilution assay, i.e., after the killing reaction has been terminated by dilution, surviving microorganisms form single colonies on agar plates but can fully outgrow in liquid media. Additionally, the conditions for resuscitation of sublethally damaged cells seem to be more favorable in the broth microdilution assay than in direct plating on agar media (4,43). Colony count assays performed with minimal media containing 1:100-instead of 1:1,000-diluted TSB showed only a marginal increase in bacterial growth for the investigated species and a markedly increased bacterial survival (Fig.…”

Putative mechanisms and biological role of coccoid form formation inCampylobacter jejuni

“…A link between CF and the VBNC form was noticed in a variety of microorganisms, for example, Actinomyces radicidentis [32], V. vulnificus [33], V. cholera [34], Mycobacterium smegmatis [35] and Salmonella typhimurium [36]. Association of CF with the VBNC state of C. jejuni would help to explain the incidences of infections by Campylobacter with no discernable environmental source [37].…”

Characterization of Mono- and Mixed-Culture Campylobacter jejuni Biofilms

“…Sanders et al (2007) also showed that C. jejuni enters the VBNC state in biofilms (34). Bacteria in the VBNC state can be resuscitated by laboratory animal challenge and mucin treatment (2,3,5,33). Although the significance of this state in the transmission of C. jejuni infection is uncertain, it has been reported that the development of the VBNC state could be a survival strategy in aquatic environments (22,42,45).…”