Assessment of in vivo revival, growth, and pathogenicity of Escherichia coli strains after copper- and chlorine-induced injury

Abstract

Cells of one enteroinvasive and three enterotoxigenic strains of Escherichia coli were exposed to sublethal concentrations of copper and chlorine to produce 85 to 94% injury. Injured cells were intraluminally inoculated into ligated ileal loops of anesthetized mice, and injury was assessed at timed intervals. Substantial recovery (72-84%) of copper-and chlorine-injured cells was observed in the inoculated loops at 4 and 3 h, respectively. No appreciable increase in total numbers was observed during these time intervals. In vitro revival of copper-injured cells in phosphate-buffered saline alone after incubation at 35°C for 4 h was not observed. However, a 60 to 70% revival occurred when 200 ,ug of protein per ml of mouse intestinal mucosal homogenate was incorporated into saline cell suspensions. The enterotoxigenic activity of copper-injured cells in rabbit ileal loops was somewhat reduced compared with that of chlorine-injured or uninjured cells. These results show that injured pathogenic E. coli cells can revive in the small intestine and appear to retain their enterotoxigenic activity.

Resistance to chlorine of freshwater bacterial strains

“…Analogously, differences in chlorination resistance attributable to encapsulation (Rudd et al 1982) or concentration of nutrients in the media (Clark 1984;Harakeh et al 1985) have been described. As it is known, either the formation or the modification processes of membrane accessory components involve protein synthesis (Walsh andBissonette 1983, 1987 ;Singh et al 1986).…”

Effect of chlorination on β-D-galactosidase activity of sewage bacteria and Escherichia coli

“…total coliforms, faecal coliforms (FC) and Escherichia coli, on agar-solidified media, or by most probable number techniques. Injured indicator bacteria have been shown to lose their ability to grow into colonies on selective media, and it is recognized that chlorine at low levels is lethal only for a fraction of the exposed bacteria but induces injury in a large proportion of the remaining cells (Green et al 1977 ;Camper and McFeters 1979 ;Egan 1979 ;LeChevallier et al 1983 ;McFeters and Camper 1983 ;Singh et al 1986Singh et al , 1990Calabrese and Bissonnette 1990). Sub-lethally injured bacteria, due to exposure to stress, may also evolve towards a viable but not cultivable stage (Xu et al 1982).…”

Flow cytometry and growth‐based analysis of the effects of fruit sanitation on the physiology of Escherichia coli in orange juice

“…Washing the cells with 200 ppm AC also resulted in a significant increase in the number of VBNC cells. The induction of VBNC in AC-stressed cells has previously been reported (Dukan, Levi, & Touati, 1997;Kolling & Matthews, 2001;Oliver, Dagher, & Linden, 2005;Singh et al, 1986).…”

“…However, these studies have only measured elimination of bacteria using plate counts; the physiological state of the bacteria has not been determined using nongrowth-based methods. Considering that an AC concentration as low as 0.4 ppm can cause sublethal injury and induce a viable but nonculturable (VBNC) state in E. coli whereby bacteria are viable but do not grow on agar plates (Kolling & Matthews, 2001;Singh, Yeager, & McFeters, 1986), and measurement of viability using plate counts could grossly underestimate the number of viable bacteria. VBNC E. coli including AC-injured bacteria have also been previously shown to be capable of revival, growth, and pathogenicity in vivo when the stress conditions were removed (Palmer, Baya, Grimes, & Colwell, 1984;Pao, Davis, Kelsey, & Petracek, 1999).…”