The Prevalence and Antimicrobial Responses of Yersinia Isolates in Comparison Toenterop Athogens Causing Diarrhoea

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Addis Ababa University


Among the stool samples of 205 patients tested for bacteriological cultures, only 6 (2.9%) were positive for Yersil/ia, 22 (10.7%) for Salmonella. 12 (5.8%) for Shigella and 11 (42.3%) for diarrhoeagenic E. coli. Out of the Yersil/ia spp. totally isolated in this study, only 3 (1.5%) were Yersil/ia enterocolitica and 3 (1.5%) were Yersil/ia pestis. Among Yersil/ia el/terocolitica strains two were isolated from children while one was from adult diarrhoeal patients. Similarly, 2 of these strains were from male patients, while 1 was from female patients. With regard to Yersinia pestis all strains were isolated from males, of which 2 were from children and one from adult diarrhoeal patient. The standardized agar disk-diffusion technique was used with disks of 13antmicrobial agents (ampicillin, carbenicillin, cephalothins, chloramphenicol, gentamycin, kanamycin, nalidixic acid, norfloxacin, polymyxin B, streptomycin, sulphadiazene, tetracycline, and trimethoprim-sulphamethoxazole. All (51) strains of enteric pathogenic bacterial isolates were sensitive to nalidixic acid, norfloxacin, and polymyxin Band 46 strains were resistant to cephalothin. Sensitivity to gentamycin, nalidixic acid, norfloxacin and polymyxin B is greater than 90% of the tested strains, while resistance to cephalothin, ampicillin and. tetracycline was greater than 50%. All strains of Yersil/ia ellterocolitica and Yersinia pestis were sensitive to carbenicillin, chloramphenicol, gentamycin, kanamycin, nalidixic acid, norfloxacin, polymyxin B, streptomycin, sulphadiazene and trimethoprim-sulphamethoxazole. All strains of Yersinia enterocolitica were resistant to ampicillin. Among Yersinia pestis strains, 66.7% were resistant to ampicillin and cephalothin respectively while 33.3% of the strains were resistant to tetracycline. Out of 22 Salmonella strains, all isolates were sensitive to norfloxacin, polymyxin B and nalidixic acid while 21 (95.5%) of strains were sensitive to gentamycin and kanamycin. Resistance was found 86.4% against cephalothin, 36.4% ampicillin and 27.0% sulphadiazene and both streptomycin and trimethoprim-sulphamethoxazole in 22.7% of these strains. Eleven different combinations of resistant patterns were observed for all the Salmonella strains. All of the 12 strains of Shigella were sensitve to nadixic acid, norfloxacin, polymyxin B, gentamycin and kanamycin. Ampicillin, carbenicillin, cephalothin, streptomycin, sulphadiazene, tetracycline and trimethoprim-sulphamethoxazole were sensitive against ::; 50% of Shigella isolates. Among the isolates, 91.7% were resistant against tetracycline, 50% against cephlothin, 75% against each of ampicillin and strepomycin. Totally, 10 different patterns of resistance were noted for Shigella spp. All strains of diarrhoeagenic E. coli were sensitive to gentamycin, kanamycin, nalidixic acid, norfloxacin and polymyxin B. While 90.9% of. them were sensitive to chloramphenicol. Of all these isolates, 81.8% strains were resistant against cephalothin and 63.6% against sulphadiazene. Based on the above sumrnerized results the prevalnece and antimicrobial response of Yersinia spp. is discussed in comparison with those of Salmonella, Shigella and E. coli isolates. According to this study, gentamycin, kanamycin, nalidixic acid, norfloxacin and polymyxin B were effective to treat diarrhoeal patients against enteropathogens.