Heat injury and repair in Campylobacter jejuni

Abstract

A procedure for detecting and quantitating heat injury in Campylobacterjejuni was developed. Washed cells of C. jejuni A7455 were heated in potassium phosphate buffer (0.1 M, pH 7.3) at 46°C. Samples were plated on brucella agar supplemented with Na2S203, FeSO4 7H20, and sodium pyruvate and on a medium containing brilliant green, bile, Na2S203, FeSO4-7H20, and sodium pyruvate. Colonies were counted after 5 days of incubation at 37°C in an atmosphere containing 5% 02, 10% C02, and 85% N2. After 45 min at 46°C, there was virtually no killing and ca. two log cycles of injury. Cells grown at 42°C were more susceptible to injury than cells grown at 37°C. The addition to brucella agar supplemented with Na2S203, FeSO4 * 7H20, and sodium pyruvate of three different antibiotic mixtures used in the isolation of C. jejuni from foods or clinical specimens did not prevent recovery of heat-injured C. jejuni. Cells lost 260 nm of absorbing materials during heat injury. The addition of 5% NaCl or 40% sucrose to the heating buffer prevented leakage but did not prevent injury. Of the additional salts, sugars, and amino acids tested for protection, only NH4CI, KCI, and LiCl2 prevented injury. Heat-injured C. jejuni repaired (regained dye and bile tolerance) in brucella broth supplemented with Na2S203, FeSO4 * 7H20, and sodium pyruvate within 4 h. Increasing the NaCl in this medium to 1.25% inhibited repair, and increasing it to 2% was lethal. Heat-injured C. jejuni will repair at 42°C but not at 5°C. Campylobacter jejuni is emerging as a bacterium of considerable importance as an agent of human diarrhea (1, 4). Some reports have even indicated that C. jejuni may be isolated from human diarrhea cases as frequently as Salmonella spp. (1, 8). The mode of transmission is currently unknown, although food has been suggested as a vehicle (2, 4). C. jejuni has been isolated from poultry (9, 12) as well as from various other foods, such as raw milk, beef, and pork (2, 4, 6, 19). Many foodborne microorganisms, including pathogens, may be stressed (sublethally injured) by food processing unit operations such as heating, freezing, drying, fermentation, and acidification (3, 18). Heat injury has been demonstrated in organisms such as Staphylococcus aureus, salmonellae, streptococci, pseudomonads, yeasts, molds, and spores (3,

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

“…However, on extended incubation, enterotoxin levels were comparable to those produced by uninjured cultures. Somewhat similar studies on thermal injury and the process of repair in Y. enterocolitica (26), Campylobacterjejuni (24), S. aureus 3, and Salmonella typhimurium (36) have been reported. In these investigations, however, the revival process was studied in in vitro systems.…”

The isolation of salmonellas and campylobacters

“…In fact, during a study of the incidence of campylobacters in frozen meat and poultry, a 2 h preenrichment culture significantly reduced the numbers isolated when compared with direct enrichment in media containing both poiymyxin B and rifampicin (Fricker, unpublished observations). Palumbo (1984) showed no inhibition of repair in heat-injured campylobacters by the three antibiotic mixtures described by Lauwers et al (1978), Skirrow (1977) and Blaser et al (1980), although none of the mixtures contained rifampicin. These conflicting results are difficult to explain but may be due to the fact that in the unpublished studies naturally contaminated materials were used, whereas the published reports describe findings based on artificially contaminated materials.…”

A comparative study of the rod and coccoid forms of Campylobacter jejuni ATCC 29428

“…The loss by converting cells of 260 nm absorbing material, observed in this study, explains the lower content of nucleic acids in coccoid forms. Such a loss from bacterial cells indicates both damage to the cell membrane and degradation of cellular components (Palumbo 1984).…”