Reduced virulence of Yersinia enterocolitica by copper-induced injury

Abstract

A sublethal concentration of copper (0.75 mg/liter) caused substantial injury (87 to 95%) of Yersinia enterocolitica serotype 0:8 cells in 72 h at 4°C without producing extensive cell death. Copper-injured cells had a higher 50% lethal dose in mice (2,700 CFU) than uninjured cells (150 CFU). This reduced virulence correlated with more rapid clearance of the injured cells from the blood of mice after intravenous inoculation. A possible role of the liver in this process was shown by significant cell accumulation in mouse livers when copper-injured Y. enterocolitica cells were administered, compared with uninjured bacteria. In vitro studies with isolated mouse liver membranes showed higher titers of aggregation with copper-injured cells than control cells. The in vitro aggregation reaction and blood clearance activity in vivo were abolished by sugars that are known to interact with a hepatic lectin. Our data suggest that copper-induced injury reduces the virulence of Y. enterocolitica and that the liver may be involved in nonimmune rapid clearance of the injured cells, probably by interaction with a hepatic lectin(s). Yersinia enterocolitica has been isolated from a variety of foods, such as raw milk (35, 38), cheese (36), raw meats (4, 37, 39), and vegetables (1), and from various water sources, such as pond and well water (9), drinking water (25), and streams and lakes (20). This organism is being increasingly recognized as the cause of a variety of infections in humans, including acute gastroenteritis, mesenteric lymphadenitis, septicemia, arthritis, and erythema nodosum (8, 42). Yersiniosis is regarded as a foodor waterborne disease because of the implication of food (3, 10, 21, 29, 46) or water (4, 14, 22, 25) in several outbreaks. Y. enterocolitica may become physiologically injured from water treatment or the processing of foods. The resulting injured population shows increased sensitivity to selective agents in the recovery medium (16). Since injured organisms generally fail to multiply in selective media used for isolation or enumeration, they remain undetected. However, induced injury in the few pathogens that have been studied (11, 18, 41) did not alter their pathogenic characteristics. This was evident after they were recovered and grown in nonselective media. In aquatic environments copper and other elements, even in trace amounts, present potentially important causes of bacterial injury. In a survey of the water supplies of the 100 largest cities of the United States, the copper concentrations ranged from 0.006 to 0.25 mg/liter (13). Other studies have

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

“…Several agents are known to injure coliform bacteria in drinking water, but copper and chlorine appear to be the most significant factors in this process (2,5,12,20). These agents have also been shown to cause injury in enteric pathogens like Yersinia enterocolitica and several strains of ETEC (13,30,31). The results of the present investigation show that different concentrations of copper and chlorine were lethal to some cells of the exposed E. coli strains but induced sublethal lesions in large proportions of the remaining population.…”

“…The effect of various stress factors on the pathogenic traits of different organisms has not been thoroughly investigated. Reduced virulence of copper-and chlorine-injured Y. enterocolitica cells in mice has been reported (13,30) recently. Heat injury of Agrobacterium tumefaciens reduces it tumorforming ability in the plant host (34).…”

“…Such an occurrence can result in serious potential health risks when waterborne pathogens are also present. However, pathogens are likewise injured when exposed to stress factors such as sublethal doses of chlorine and copper (13,30), heat (3), and the process of freeze-drying (7). Sublethally injured Staphylococcus aureus (7) and E. coli strains (31), as well as "viable but not recoverable" ETEC (23) cells, have been shown to regain their pathogenic traits when transferred to suitable in vitro environments.…”

Serovars of Multi‐Antibiotic Resistant Escherichia coli from the Freshwater Environs of Calcutta, India

“…Reduced virulence has been demonstrated for various waterborne pathogens including ETEC, Yersinia enterocolitica, Salmonella typhimurium, and Shigella spp. following sublethal aquatic injury (21,38,39,43). According to Walsh and Bissonnette (44) the sites involved in the processing, synthesis and release of LT by ETEC may be affected when these organisms are exposed to extraenteral habitats that can cause injury to the organisms.…”

INJURY AND SURVIVAL OF AEROMONAS HYDROPHILA 7965 AND YERSINIA ENTEROCOLITICA 9610 FROM HIGH HYDROSTATIC PRESSURE

“…Sublethal injury has been demonstrated from exposure to copper in Y. enterocolitica (Singh et al 1985), from exposure to chlorine in Escherichia coli (Singh et al 1986), and from exposure to microwave and conventional heating in Staphylococcus aureus (Khalil and Villota 1988). Injury is usually quantified by plate count using a nonselective medium supplemented with a selective agent such as sodium chloride (Palumbo 1989).…”