Abstract
This study aimed to detect Escherichia coli O157:H7 in samples from patients with diarrhea, sheep milk, and sheep drinking water by growth on selective media, biochemical tests, latex agglutination test, and PCR technique. During the period from November 2008 to May 2009, a total of 340 samples were collected; stools diarrhoeic patients (125), healthy sheep feces (125), milk (45), and sheep drinking water samples (45). Samples were screened for the presence of non-sorbitol fermenting colonies (NSF) on sorbitol MacConkey agar supplemented with cefixime and potassium tellurite (CT-SMAC). Out of the 340 samples, 58 (46.4%) stool from diarrhea, 98 (78.4%) from sheep feces, 19 (42.2%) milk, and 17 (37.7%) drinking water were nonsorbitol fermenting. E. coli isolates were serotyped as E. coli O157:H7 by latex agglutination test, 3 (5.7%) isolates of stool from diarrhea patients, 7 (7.3%) isolates of sheep feces, 2 (11.1%) isolates of milk, and none of drinking water samples were positive. All latex agglutination positive isolates were positive to PCR test except one isolate from sheep feces. PCR positive isolates were produced enterohemolysin on sheep blood agar, and were found resistant to at least 3 antibiotics. The highest rate of E. coli O157:H7 isolation was observed in April (7.6%) followed by December (4.7%) , while those of sheep feces showed the highest rate in March (10%) followed by April (8.6%).
Highlights
This study aimed to detect Escherichia coli O157:H7 in samples from patients with diarrhea, sheep milk, and sheep drinking water by growth on selective media, biochemical tests, latex agglutination test, and PCR technique
The frequency of non-sorbitol fermenting colonies (NSF) E. coli was 46.4% in human stool samples, 78.4% in sheep fecal samples, 42.2% in milk samples, and 37.7% in water samples based on non-sorbitol fermintation in TC-SMAC
Based on Chi-squar statistical analysis, the results revealed significant differences between the isolation frequency from human and sheep while there are no significant differences in isolation frequency in human, milk, and water samples (Table 2)
Summary
This study aimed to detect Escherichia coli O157:H7 in samples from patients with diarrhea, sheep milk, and sheep drinking water by growth on selective media, biochemical tests, latex agglutination test, and PCR technique. Out of the 340 samples, 58 (46.4%) stool from diarrhea, 98 (78.4%) from sheep feces, 19 (42.2%) milk, and 17 (37.7%) drinking water were nonsorbitol fermenting. E. coli isolates were serotyped as E. coli O157:H7 by latex agglutination test, 3 (5.7%) isolates of stool from diarrhea patients, 7 (7.3%) isolates of sheep feces, 2 (11.1%) isolates of milk, and none of drinking water samples were positive. This study was designed to detect E. coli O157:H7 in sheep as a major reservoir and as a causative agent for diarrhea patients, and to characterize these isolates by means of biochemical tests, serotyping and PCR techniques
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