1067 Journal of Food Protection, Vol. 53, No. 12, Pages 1067-1068 (December 1990) Copyright© International Association of Milk, Food and Environmental Sanitarians /4 1£e&e*nc& 1fote Cross-contamination with Campylobacter jejuni and Salmonella spp. from Raw Chicken Products During Food Preparation ENNE DE BOER* and MARCEL HAHNE Downloaded from http://meridian.allenpress.com/jfp/article-pdf/53/12/1067/1659752/0362-028x-53_12_1067.pdf by guest on 24 September 2021 Inspectorate for Health Protection, P.O. Box 9012, 7200 GN Zutphen, The Netherlands (Received for publication April 11, 1990) ABSTRACT was prepared using a Stomacher. For the Campylobacter isola­ tion, 1 ml of this suspension was added to 10 ml of CCDB Campylobacter jejuni was isolated from 170 (61%) of 279 enrichment medium (1). After microaerobic incubation during samples of chicken products and Salmonella from 44 (54%) of 24 h at 42°C, a loopful of enrichment broth was streaked on 81 samples. Cross-contamination experiments showed that C. Skirrow's medium or CCDA medium (1). The isolation media jejuni and to a lesser extent Salmonella were easily transferred were incubated microaerobically for 48 h at 42°C. Suspected from raw chicken products to cutting-boards, plates, and hands. colonies were identified by a positive oxidase test and typical These organisms were also isolated from raw vegetables and morphology and motility on microscopy. For the Salmonella cooked chicken products, which were in contact with plates on isolation, the remaining suspension was incubated for 16-20 h at which raw chicken products had been placed. Measures for the 37°C. From this preenrichment culture, 0.1 ml was added to 10 prevention of infection by cross-contamination through handling ml Rappaport-Vassiliadis enrichment broth (Oxoid) and 10 ml of raw chicken are mentioned. to 100 ml of tetrathionate brilliant green bile enrichment broth (Merck). After 24 and 48 h incubation at 42°C, a loopful of Campylobacter jejuni and Salmonella spp. are respon­ enrichment broth was streaked on brilliant green agar (Oxoid). sible for about 15 and 5%, respectively, of all cases of The plates were incubated for 24 h at 37°C. Suspected colonies acute enteritis in man in the Netherlands. Both organisms were identified using the API-20E system and Salmonella agglu­ tination sera. are frequently isolated from poultry products, and it is Cross-contamination experiments clear from epidemiological studies that these products play Experiment 1: Two swabs were taken from cutting-boards an important role in campylobacteriosis. on which raw chickens have been cut. Undercooking and cross-contamination of cooked foods Experiment 2: Chicken products were placed on plates for from raw chicken are the main causes of Campylobacter 5 min, and the products were moved over the plates several and Salmonella infections related to chicken products. times. Directly after removal of the products, two swabs were Though the role of cross-contamination in the cause taken from the plates. One of each swab of the sampled cutting- of foodborne infections is generally known, few data have board or plate was placed immediately into CCDB and further been published on quantitative aspects of cross-contami­ analyzed for Campylobacter. The second swab was placed in nation risks in the practice of food preparation. This paper buffered peptone water and further analyzed for Salmonella. describes some experiments in which contamination of Experiment 3: Chicken products were placed on plates for surfaces (cutting-boards, plates), ready-to-eat foods (raw 5 min and after removal of the products, raw vegetables were vegetables, cooked chicken), and hands with C. jejuni and put on the plates and moved over the plates some times using a fork. Next, the raw vegetables were analyzed for Campylobacter Salmonella from raw chicken was estimated. and Salmonella. MATERIALS AND METHODS Experiment 4: Chicken products were placed on plates for 5 min and then heated on another plate in a microwave oven for Samples 15 min at 80°C. The heated products were then placed on the Chicken products (drumsticks, wings, livers, fillets, etc.) same plate where they were in the raw state and moved over the were sampled in retail outlets. Parts of the samples were tested plates several times. Next, the heated products were analyzed for the presence of C. jejuni and Salmonella. The remaining for Campylobacter and Salmonella. parts of the samples were used for cross-contamination experi­ Experiment 5: Chicken products were held in clean hands ments. for 1 min. Next, the hands were put in plastic gloves containing 20 ml of either CCDB or buffered peptone water with 0.1% Isolation of Campylobacter jejuni and Salmonella Tween 80 (6). The contents of the gloves were analyzed for A 1:10 suspension of the samples of chicken meat (fillet), Campylobacter and Salmonella. The experiments were repeated, chicken giblets (liver, stomach), or chicken skin (drumsticks, whereby after holding the chicken products, 3 min, were waited wings) in buffered peptone water (Oxoid, Basingstoke, England) before the hands were put in the gloves with enrichment media. JOURNAL OF FOOD PROTECTION, VOL. 53, DECEMBER 1990 1068 DE BOER AND HAHNE RESULTS AND DISCUSSION eat foods. Direct risks of infection will especially occur because the minimal infectious dose for Campylobacter is Campylobacter and Salmonella in chicken products probably low (//) and for Salmonella can be low (4). Campylobacter jejuni was isolated from 170 (61%) of When the hands were sampled 3 min after holding the 279 chicken products, while Salmonella was isolated from chicken products, C. jejuni was isolated from 30 (55%) 44 (54%) of 81 chicken products. These results confirm and Salmonella from 4 (12%) of the hands (54 experi­ the high incidence of C. jejuni and Salmonella in chicken ments). So, Campylobacter and Salmonella survived a 3 products. No other food in The Netherlands is contami­ min "drying" period. Though Campylobacter and Salmonella nated with these pathogens to such a degree. For compari­ can survive on hands for a rather long time (3,10), in son, in minced meat (pork) we recently found 8 of 104 practice cross-contamination is likely to occur before the samples Salmonella-positive, while C. jejuni was isolated fingers have dried (3). from only one of these samples. In epidemiological studies it was shown that the handling of raw chicken or the preparing of chicken was associated Cross-contamination experiments with Campylobacter enteritis (2,8). Cross-contamination Downloaded from http://meridian.allenpress.com/jfp/article-pdf/53/12/1067/1659752/0362-028x-53_12_1067.pdf by guest on 24 September 2021 After removal of raw chicken products from cutting- can easily occur at barbecues and in similar situations, boards and plates, C. jejuni was isolated from 38 (50%) of where direct contact with raw meat is likely to occur. the 76 tested cutting-boards and from 25 (46%) of the 54 Measures for the prevention of infection by cross- tested plates. The isolation rates for Salmonella from these contamination through the handling of raw chicken should surfaces were much lower, namely 6% (4 of 71) and 5% include: a) preventing direct hand contact with raw chicken; (3 of 57). b) careful washing and drying of hands after handling raw The difference in the degree of transfer of C. jejuni chicken; c) thorough cleaning of surfaces (cutting-boards, and Salmonella may be due to the method used, in which plates) after contact with raw chicken; d) strict separation the first swab was always analyzed for C. jejuni and the of raw chicken and ready-to-eat foods; and e) use of second swab for Salmonella. Also, a difference in the previously cooked chicken at barbecues. attachment of these bacteria to chicken may have made a difference. REFERENCES The viability of transferred organisms will largely depend on the simultaneously transferred amount of liquid. 1. Bolton, F. J., D. N. Hutchinson, and D. Coates. 1984. Blood-free se­ Campylobacter is very sensitive to drying. When contami­ lective medium for isolation of Campylobacter jejuni from faeces. J. Clin. Microbiol. 19:169-171. nated spin-chiller water was spread on tiles of different 2. Brown, P., D. Kidd, T. Riordan, and R. A. Barrell. 1988. An outbreak materials, the organism survived as long as moistened surface of food-borne Campylobacter jejuni infection and the possible role of could be observed (9). Salmonella is less sensitive to drying. cross-contamination. J. Infect. 17:171-176. This organism could be isolated from artificially contami­ 3. Coates. D.. D. N. Hutchinson, and F. J. Bolton. 1987. Survival of ther­ mophilic Campylobacters on fingertips and their elimination by wash­ nated surfaces up to 6 h after the surface had dried (5). ing and disinfection. Epidemiol. Infect. 99:265-274. Chicken liquor and blood were found to have a protective 4. D'Aoust, J.-Y., and H. Pivnick. 1976. Small infectious doses of effect on Campylobacter (3), while beef serum showed a Salmonella. Lancet i:866. protective effect on Salmonella during drying (7). 5. De Wit, J. C„ G. Broekhuizen, and E. H. Kampelmacher. 1979. Cross- contamination during the preparation of frozen chickens in the Campylobacter jejuni was isolated from five (9%) and kitchen. J. Hyg. (Camb.) 83:27-32. Salmonella from three (6%) of 54 samples of raw vege­ 6. De Wit, J. C, and E. H. Kampelmacher. 1981. Some aspects of micro­ tables, which were in contact with plates on which raw bial contamination of hands of workers in food industries. Zbl. Bakt. chicken products had been placed. For cooked chicken Hyg., 1. Abt. Orig. B 172:390-400. 7. Dyer, R. L., and R. B. Maxcy. 1982. Fate of Escherichia coli and Sal­ products these percentages were 10% (2 of 21) for C.