Improved procedure for recovery of Yersinia enterocolitica from meats.
A 1- to 3-day enrichment-KOH postenrichment procedure was evaluated and found to be as effective in recovering Yersinia enterocolitica from meats as a 14- to 21-day cold enrichment procedure, with or without KOH postenrichment. The shortened procedure consists of enriching 1.0- and 25-g samples of meat in phosphate-buffered saline (pH 7.2) at 25 degrees C. After incubation (48 and 72 h for 1.0-g samples and 24 and 48 h for 25-g samples); 0.5-ml portions of enrichment culture were treated with 4.5 ml of 0.25% KOH-0.5% NaCl for 2 min and 0.5% KOH-0.5% NaCl for 15 s, and 0.1-ml portions of treated culture were plated onto MacConkey or CIN agars or both. The procedure effectively recovered 2 to 12 cells of a number of both mouse-virulent and avirulent strains per g of ground beef with aerobic plate counts of approximately 10(6) to 10(7) CFU/g. Similarly, the procedure isolated both likely virulent and avirulent strains from porcine tongues (aerobic plate counts of 10(5) to 10(7) CFU/g) naturally contaminated with Y. enterocolitica. The organism was isolated from the tongues at similar rates by both shortened enrichment and cold enrichment procedures. Eight tongues were positive for serotype O:5,27 strains that agglutinate with WA-specific absorbed antiserum, an antiserum specific for mouse-virulent Y. enterocolitica (Doyle et al., Infect. Immun. 37:1234-1240, 1982), indicating that the oral cavity of swine is a reservoir of likely virulent serotype O:5,27 strains.
D000818:Animals; D002417:Cattle; D005516:Food Microbiology; D006878:Hydroxides / Q000494:pharmacology; D008460:Meat; D008461:Meat Products; D008722:Methods; D011188:Potassium / Q000494:pharmacology; D017680:Potassium Compounds; D013552:Swine; D014059:Tongue / Q000382:microbiology; D015008:Yersinia enterocolitica / Q000302:isolation & purification*
D006878:Hydroxides; D017680:Potassium Compounds; D011188:Potassium; C029943:potassium hydroxide