Staphylococcal Infection in Meat Animals and Meat Workers
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Staphylococcal Infection in Meat Animals and Meat Workers REIMERT T. RAVENHOLT, M.D., M.P.H., ROBERT C. EELKEMA, D.V.M., M.D., MARIE MULHERN, B.S., and RAY B. WATKINS, D.V.M. most of the serious and fatal ing an Acronizing process (chlortetracycline re¬ ALTHOUGHu cases of staphylococcal disease in Seattle HC1) about May 15, 1956. The antibiotic and King County, Wash., occur among hospital¬ placed chlorine in the ice water bath in which ized patients suffering from other diseases the chickens were immersed for 4-6 hours after (1-5), several recent incidents suggested that they were killed, cleaned, and eviscerated. It the community has nonhospital reservoirs of was claimed that the Acronizing process ex¬ staphylococcal infection which may be impor¬ tended the "shelf life" of the poultry, permit¬ tant in the ecology of staphylococci. ting the holding of chickens at ordinary refrig¬ One such incident was an outbreak of boils erator temperature for as long as 14 days. Most (pyoderma) among workers in a poultry-proc¬ of the workers, however, had little if any direct essing establishment in Seattle. An investiga¬ contact with the Acronizing process. tion in October 1956 revealed that from May Investigation of the outbreak also revealed through September of that year 19 (63 percent) that abscesses, especially along the keel bone, of the 30 poultry handlers in the establishment were sometimes observed in chickens. The plant developed boils and other suppurative skin le¬ manager and sanitary inspector were instructed sions. Most of the afflicted workers missed a to submit any abscessed poultry carcasses for few days from work, and several more than a culture. One such bird, with an abscess along week. Cultures prepared from specimens ob¬ the keel bone, was submitted and yielded tained from three patients with active lesions a coagulase-positive S. aureus, bacteriophage yielded coagulase-positive Staphylococcus au¬ type 7. Letters were sent to the 21 growers reus, bacteriophage type 52/42B/81 (now who had supplied poultry to the processing known as type 80/81). plant during 1956 asking whether they had ob¬ Investigation of possible epidemiogenic fac¬ served any unusual disease in their flocks and tors revealed that this poultry plant began us- what antibiotics they had used in raising the poultry. Thirteen of the 15 growers who re¬ had used in Dr. Ravenholt is director of the division of epidemi¬ plied stated that they tetracycline ology and communicable disease control, Seattle- raising the chickens sold to this poultry plant. King County (Wash.) Department of Public Health, None, however, reported unusual or staphy- and clinical assistant professor of public health and lococcal-like disease amongtheir birds. medicine, University of Washington. Another incident occurred in December 1959. preventive At least 30 members of a union be¬ Dr. Eelkema, a medical student at the University of carpenters' came ill with food Washington at the time of the study, is now an severely staphylococcal intern at the Public Health Service Hospital in Seat¬ poisoning after eating ham at a union-spon¬ tle. Miss Mulhern is director of the laboratory sored dinner. Investigation revealed the fol¬ division, and Dr. Watkins is chief of the meat inspec¬ lowing epidemiology: A tinned ham, purchased tion program, Seattle-King County Health Depart¬ at a supermarket, was removed from its can, ment. sliced by machine, wrapped in aluminum foil, Vol. 76, No. 10, October 1961 879 and delivered to a woman who assisted with cooked, refrigerated ham from the same res¬ preparation of the meal. She baked the sliced taurant revealed a few mixed, gram-positive ham, still wrapped in foil, for about <21/2 hours bacteria by direct smear and approximately at 300° F. and then left it at room temperature 1,000 organisms per gram of ham by culture. until it was served the following day. Coagu¬ No coagulase-positive staphylococci were iso¬ lase-positive staphylococci, bacteriophage type lated from the refrigerated ham initially, but 6/7/47/54/70/73/75, were isolated from (a) when a portion of the same specimen of ham the remnant of canned ham served at the din¬ was incubated at 35° C. for 36 hours it con¬ ner, (b) a throat swab specimen from the cook tained a bacterial count of more than 1 billion who prepared (and also ate) the ham, (c) organisms per gram of ham, including coagu¬ throat swab specimens (obtained after re¬ lase-positive S. aureus, not typable by means covery) from two food-poisoning victims, and of bacteriophage. Specimens of vomitus and (d) swab specimens from infected cuts on the stool from one hospitalized diner were hands of two meat cutters in the supermarket, examined. No coagulase-positive staphylococci one of whom had sliced the ham. No viable were isolated from the vomitus, but coagulase- staphylococci were isolated from a canned ham, positive S. aureus, not typable by bacterio¬ not previously opened, from the same lot as the phage, was isolated from the stool. Further¬ one causing food poisoning. On questioning, more, the specimens were negative for Salmo¬ the meat cutters stated that knife cuts (which nella, Shigella, and pathogenic Escherichia coli. they inflict on themselves frequently) had be¬ These findings indicated that the raw ham come suppuratively infected about a month be¬ was lightly seeded with a variety of organisms, fore the outbreak occurred. They also said including pathogenic staphylococci, at the time that such infections, which they referred to as it was received by the restaurant, and that the "pork infection," occurred most frequently in incubatory infrared lamps then caused great the spring and fall. multiplication of organisms, especially the Apparently, the meat cutter inoculated the pathogenic staphylococci which caused the acute ham with pathogenic staphylococci while gastroenteritis. slicing the ham, and leaving the ham at room These incidents suggested that considerable temperature after it was inadequately cooked staphylococcal disease may derive, either di¬ permitted greatmultiplication of the organisms. rectly or indirectly, from nonhuman reservoirs The findings suggested that meat, particularly of infection. To explore this possibility, a pork, might expose meat cutters to an occupa¬ study of staphylococcal infection in meat ani¬ tional risk of stapylococcal infection of cuts. mals slaughtered in this and in A third community per¬ incident took place in June 1960. At sons slaughtering these animals or processing least three persons became severely ill with the meat was made in the summer of 1960. The acute gastroenteritis several hours after eating availability of an investigator with both vet¬ ham sandwiches in a Seattle restaurant. These erinary and medical training (R.C.E.) greatly persons ate ham which had been cooked by ex¬ facilitated the undertaking. posure to infrared lamps for at least 18 hours and as as 36 hours. The measured perhaps long Method of Investigation temperature of another ham similarly held un¬ der the infrared lamps was 112° F. The approximate number of meat-handling Laboratory examination of specimens of the establishments in Seattle and the number of implicated ham in this incident showed many employees.slaughterers, cutters, boners, wrap¬ gram-positive cocci by direct smear and a bac¬ pers, sausage workers, packagers, and other terial count of approximately 100 million handlers.was ascertained by means of ques¬ organisms per gram of ham by culture. The tionnaires with the assistance of the six meat only pathogenic organisms identified as part of inspectors employed by the health department. the heavy bacterial growth were coagulase- The number of pounds of meat from animals positive S. aureus, which were not typable by slaughtered in Seattle and King County abat¬ means of bacteriophage. A specimen of an un¬ toirs was ascertained from city, State, and 880 Public Health Reports Federal officials who routinely inspect these with associated inflammation, lymphangitis establishments. ("streaking"), and fever, necessitating medical To learn the nature and prevalence of staphy¬ treatment and referred to as "blood poisoning," lococcal infection among meat animals and "pork infection," or "fish poisoning" by the meat workers, 15 establishments, including 2 workers. slaughter, 5 wholesale, 3 poultry, and 5 fish Each employee was also given a dermatologi- establishments, were selected for intensive cal examination. Men were stripped to the study. They were chosen because (a) they waist; for women, the head, neck, and upper, were located in Seattle, (b) they were among extremities were examined. Swab specimens the largest of their respective kinds of estab¬ for culture were obtained from any suppura- lishments (there are only three poultry-process¬ tive skin lesions observed and routinely from ing houses in Seattle), and (c) their manage¬ the nostrils. These specimens were immedi¬ ments agreed to cooperate. ately transported to the laboratory of the Seat¬ For each of 318 (all) workers having direct tle-King County Health Department and contact with raw meat in these 15 establish¬ cultured by standard methods, using Chapman- ments, histories were obtained by direct per¬ Stone medium. sonal interview. The histories covered job Abattoir inspectors were asked to save all classification, employment tenure as a meat han¬ suppurative lesions observed in meat and to dler, and experience with boils and "blood notify the investigators. These specimens were poisoning," or "septicemia." The term "sep¬ also immediately taken to the laboratory of the ticemia" is used in this article to denote wounds Seattle-King County Health Department and Table 1. Age, sex, and meat-handling experience of workers in selected meat establishments, 1960 survey, Seattle, Wash. Number Number of workers Average Total number Median number Type of establishment of age worker-years of worker-years establish¬ (years) meat-handling in meat ments Total Male Female experience handling Slaughterhouse_ 92 70 22 40 1,146 8.5 Wholesale meat house_ 85 55 30 36 917 6.0 Poultry house_ 77 26 51 40 690 6.0 Fish house_ 64 51 13 40 857 7.0 TotaL 15 318 202 116 39 3,610 7.0 Table 2.