The effect of temperature and the availability of nutrients on the transition of spiral Campylobacter jejuni cells to coccoid forms was investigated. Ageing of spiral C. jejuni cells in either nutrient-poor or nutrient-rich environments resulted in the formation of nonculturable coccoid cells at 4, 12, and 25؇C after different periods, with the cells incubated at 4؇C in nutrient-deficient media remaining culturable the longest. To study the phenomenon, ATP levels, protein profiles, and fatty acid compositions were monitored under conditions where the transition from spiral to coccoid cells occurred. During storage, the levels of intracellular ATP were highest in cells incubated at low temperatures (4 and 12؇C) and remained constant after a small initial decrease. During the transformation from spiral to coccoid forms, no alteration in protein profiles could be detected; indeed, inhibition of protein synthesis by chloramphenicol did not influence the transition. Furthermore, DNA damage by gamma irradiation had no effect on the process. Membrane fatty acid composition of cocci formed at low temperatures was found to be almost identical to that of spiral cells, whereas that of cocci formed at 25؇C was clearly different. Combining these results, it is concluded that the formation of cocci is not an active process. However, distinctions between cocci formed at different temperatures were observed. Cocci formed at 4؇C show characteristics comparable to those of spirals, and these cocci may well play a role in the contamination cycle of C. jejuni. However, spiral campylobacters can also play an important role in this cycle, since these cells remain culturable for a long period, especially under nutrient-poor and low-temperature conditions.

Campylobacteriosis is one of the most frequently occurring acute gastroenteritis diseases in humans. Studies have revealed that the main risk factors in contracting campylobacteriosis are eating undercooked poultry meat, drinking raw milk, or drinking untreated water, and to a lesser degree, living in a household with a cat or dog.During the past 5 years many transmission routes of Campy/obaeter have been elucidated. However, knowledge on the significance of surface waters in causing Campy/obaeter infections remains scarce. Various reports have shown that the aquatic environment is regularly contaminated with Campy/obaeter. Risk analysis indicates that the contribution of contaminated recreational water to human infections may be higher than previously assumed. The contribution of viable but nonculturable Campy/obaeter cells in the contamination cycle has been found to be negligible. Water Environ. Res., 69,52 (1997).

Fifty-six dairy bacteria belonging to the genera Lactococcus, Lactobacillus, Pediococcus, Propionibacterium, Streptococcus, Enterococcus, Leuconostoc, and Brevibacterium were screened for antifungal activity against four species of fungi relevant to the cheese industry (Penicillium discolor, Penicillium commune, Penicillium roqueforti, and Aspergillus vesicolor). Most of the active strains belonged to the genus Lactobacillus, whereas Penicillium discolor was found to be the most sensitive of the four fungi investigated. Further studies on P. discolor showed antifungal activity only below pH 5. This effect of pH suggests that organic acids present in the culture could be involved in the detected activity. Determination of acid composition revealed lactic acid production for active dairy strains and the presence of acetic acid in active as well as inactive strains. It was demonstrated that the undissociated acetic acid originates from the bacterial growth medium. The synergistic effect of the acetic acid present and the lactic acid produced was likely the main factor responsible for the antifungal properties of the selected bacteria. These results could explain some discrepancies in reports of the antifungal properties of lactic acid bacteria, since the role of acetic acid has not been considered in previous studies.

SUMMARYRecently, an increased resistance of Campylobacter to fluoroquinolones, a newer class of antimicrobial agents in both human and veterinary medicine, has been reported. Campylobacter isolates (617) from 150 broiler flocks were tested for their susceptibility to cephalothin (control), ampicillin, tetracycline, erythromycin, and the quinolones nalidixic acid, flumequine, enrofloxacin, and ciprofloxacin by a disc diffusion method. Almost complete cross-resistance was found between the quinolones tested. Campylobacter isolates (181, 29%), originating from 55 flocks (37%), were quinolone resistant. Salmonella isolates (94) from 40 flocks were also tested for their antimicrobial susceptibility. Eight isolates (8.5%), from three broiler flocks (7.5%), showed resistance to nalidixic acid and flumequine (and tetracycline), but not to ciprofloxacin or enrofloxacin.

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