Potentially zoonotic shiga toxin-producing Escherichia coli serogroups in the faeces and meat of food-producing animals in Ibadan, Nigeria.

Shiga toxin-producing Escherichia coli (STEC) are major food-borne pathogens associated with gastroenteritis and sometimes fatal haemolytic uraemic syndrome complication. Farm animals are asymptomatic carriers of STEC and contaminated meat is an important vehicle for zoonotic transmission from animals to humans. This study investigated the presence, virulence traits and antimicrobial susceptibility of seven potentially human pathogenic STEC serogroups (O157, O26, O91, O103, O111, O128 and O145) in the faeces and meat of food-producing animals in Ibadan, Nigeria. One hundred and fifty-four (7.3%) of 2133 samples were positive for STEC serogroups. The pathogens were detected in the faeces of cattle (15.2%), sheep (10.7%), goats (7.5%) and pigs (5.6%) as well as in beef (3.8%), goat-meat (1.7%) and pork (4.0%). All seven investigated STEC serogroups were found in cattle, all except O145 were found in sheep, three serogroups (O157, O26 and O111) were found in goats and three (O157, O111 and O128) in pigs. The rate of detection of each of the serogroups in all 2133 samples was: O157 (5.0%), O26 (0.2%), O91 (0.3%), O103 (0.3%), O111 (1.0%), O128 (0.2%) and O145 (0.1%). Of all 154 isolates, 11.0% had shiga toxin type 1 gene (stx(1)), 25.3% had stx(2) and 41.6% had stx(1)/stx(2); intimin gene (eaeA) was detected in 56.5% and enterohaemolysin gene (hlyA) in 75.3%. Among the O157 isolates, 24.5% were negative for stx genes but positive for eaeA and/or hlyA while 7.6% were negative for all four virulence genes. Fourteen different combinations of virulence genes were encountered but stx(1)/stx(2)/eaeA/hlyA combination was the most predominant. The percentage resistance of the isolates to the tested antimicrobial agents was: ampicillin (82.5%), chloramphenicol (42.9%), ciprofloxacin (22.1%), enrofloxacin (25.3%), nalidixic acid (37.7%), neomycin (24.0%), norfloxacin (20.8%), streptomycin (50.7%) and tetracycline (75.3%). One hundred and forty-eight (96.1%) of all 154 isolates were resistant to at least one of the tested antimicrobial agents while 69.5% were categorised as multi-drug resistant. Potentially pathogenic multi-drug resistant STEC isolates were recovered from the meat production chain in Nigeria. Unhygienic practices that predominate during slaughter and processing were observed to have contributed to faecal contamination and presence of STEC in meat.

Ojo OE ，Ajuwape AT ，Otesile EB ，Owoade AA ，Oyekunle MA ，Adetosoye AI ... -  《-》

Escherichia coli O157:H7 and non-O157 Shiga toxin-producing E. coli in healthy cattle, sheep and swine herds in Northern Spain.

Three-hundred and forty-five herds (17 swine, 122 dairy sheep, 124 beef and 82 dairy cattle) were investigated for prevalence of Shiga toxin-producing Escherichia coli (STEC). Rectal faecal samples were selectively enriched and then examined by immunodetection techniques (Immunomagnetic Separation with anti-E. coli O157 Dynabeads, ImmunoMagnetic cell Separation (IMS) and automated enzyme-linked fluorescent immunoassay using VIDAS) and polymerase chain reaction (PCR) (rfbE and fliC genes) to assess the prevalence of E. coli O157:H7. Prevalence of non-O157 STEC was estimated by PCR screening for stx genes of 10 lactose-positive colonies grown on MacConkey agar after enrichment. PCR was used on all STEC isolates to detect stx(1), stx(2), eaeA and E-hlyA genes. Both immunodetection methods showed a moderate-good level of agreement (kappa = 0.649) but IMS showed 87.5% complementary sensitivity. Prevalence of positive herds for E. coli O157:H7 was estimated at 8.7% for sheep and 3.8% for cattle, whereas all the porcine herds tested negative. Non-O157 STEC were also absent from swine, but were isolated more frequently from ovine (50.8%) than bovine herds (35.9%). Within-herd prevalences of excretion of E. coli O157:H7 established by individual testing of 279 sheep (six herds) and 30 beef cattle (one herd) were 7.3% and 6.7% respectively. PCR analysis of 49 E. coli O157:H7 and 209 non-O157 isolates showed a different distribution of virulence genes. All E. coli O157:H7 were stx(2) gene-positive, eaeA was detected in 95.9%, and the toxigenic profile stx(2)/eaeA/E-hlyA was present in 75.5% of the isolates. Among the non-O157 STEC, prevalence of eaeA was significantly lower (5.3%) and E-hlyA was present in 50.2% of the isolates but only sporadically associated with eaeA. stx(2) was predominant in non-O157 isolates from cattle, whereas in sheep the combination stx(1)/stx(2) was more prevalent. This study demonstrated the wide distribution of STEC in ruminant herds, which represent an important reservoir for strains that pose a potential risk for human infections.

Oporto B ，Esteban JI ，Aduriz G ，Juste RA ，Hurtado A ... -  《Zoonoses and Public Health》

Antimicrobial resistance of Shiga toxin (verotoxin)-producing Escherichia coli O157:H7 and non-O157 strains isolated from humans, cattle, sheep and food in Spain.

A total of 722 Shiga toxin-producing Escherichia coli (STEC) isolates recovered from humans, cattle, ovines and food during the period from 1992 to 1999 in Spain were examined to determine antimicrobial resistance profiles and their association with serotypes, phage types and virulence genes. Fifty-eight (41%) out of 141 STEC O157:H7 strains and 240 (41%) out of 581 non-O157 STEC strains showed resistance to at least one of the 26 antimicrobial agents tested. STEC O157:H7 showed a higher percentage of resistant strains recovered from bovine (53%) and beef meat (57%) than from human (23%) and ovine (20%) sources, whereas the highest prevalence of antimicrobial resistance in non-O157 STEC was found among isolates recovered from beef meat (55%) and human patients (47%). Sulfisoxazole (36%) had the most common antimicrobial resistance, followed by tetracycline (32%), streptomycin (29%), ampicillin (10%), trimethoprim (8%), cotrimoxazole (8%), chloramphenicol (7%), kanamycin (7%), piperacillin (6%), and neomycin (5%). The multiple resistance pattern most often observed was that of streptomycin, sulfisoxazole, and tetracycline. Ten (7%) STEC O157:H7 and 71 (12%) non-O157 strains were resistant to five or more antimicrobial agents. Most strains showing resistance to five or more antimicrobial agents belonged to serotypes O4:H4 (4 strains), O8:H21 (3 strains), O20:H19 (6 strains), O26:H11 (8 strains eae-beta1), O111:H- (3 strains eae-gamma2), O118:H- (2 strains eae-beta1), O118:H16 (5 strains eae-beta1), O128:H- (2 strains), O145:H8 or O145:H- (2 strains eae-gamma1), O157:H7 (10 strains eae-gamma1), O171:H25 (3 strains), O177:H11 (5 strains eae-beta1), ONT:H- (3 strains/1 eae-beta1) and ONT:H21 (2 strains). Interestingly, most of these serotypes, i.e., those indicated in bold) were found among human STEC strains isolated from patients with hemolytic uremic-syndrome (HUS) reported in previous studies. We also detected, among non-O157 strains, an association between a higher level of multiple resistance to antibiotics and the presence of the virulence genes eae and stx(1). Moreover, STEC O157:H7, showed an association between certain phage types, PT21/28 (90%), PT23 (75%), PT34 (75%), and PT2 (54%), with a higher number of resistant strains. We conclude that the high prevalence of antimicrobial resistance detected in our study is a source of concern, and cautious use of antibiotics in animals is highly recommended.

Mora A ，Blanco JE ，Blanco M ，Alonso MP ，Dhabi G ，Echeita A ，González EA ，Bernárdez MI ，Blanco J ... -  《RESEARCH IN MICROBIOLOGY》

Application of a real-time PCR-based system for monitoring of O26, O103, O111, O145 and O157 Shiga toxin-producing Escherichia coli in cattle at slaughter.

Faecal samples were collected from 573 slaughtered cattle aged between three and 24 months in seven abattoirs. After enrichment (mTSB with novobiocin), samples were screened by real-time PCR first for stx and if positive, tested for the top-five Shiga toxin-producing Escherichia coli (STEC) serogroups using PCR assays targeting genes specific for serogroups O26, O103, O111, O145 and O157. Of 563 samples with available results, 74.1% tested positive for stx genes. Amongst them, the serogroups O145, O103, O26, O157 and O111 were detected in 41.9%, 25.9%, 23.9%, 7.8% and 0.8%, respectively. From 95 O26, 166 O145 and 30 O157 PCR-positive samples, 17 O26, 28 O145 and 12 O157 strains were isolated by colony hybridization after immunomagnetic separation. The 17 O26 strains were eae-positive, but only nine strains harboured stx (eight possessing stx1 and one stx2). Of the 28 O145 strains, ten were eae-positive including four harbouring stx1 or stx2, whereas 18 were negative for stx and eae. Five of the 12 O157 strains harboured stx2 and eae, did not ferment sorbitol, and were identified as STEC O157:H7/H⁻. The other seven O157 strains were negative for stx and eae or positive only for eae. Shiga toxin genes and the top-five STEC serogroups were frequently found in young Swiss cattle at slaughter, but success rates for strain isolation were low and only few strains showed a virulence pattern of human pathogenic STEC.

Hofer E ，Stephan R ，Reist M ，Zweifel C ... -  《-》

Summer and Winter Prevalence of Shiga Toxin-Producing Escherichia coli (STEC) O26, O45, O103, O111, O121, O145, and O157 in Feces of Feedlot Cattle.

Dewsbury DM ，Renter DG ，Shridhar PB ，Noll LW ，Shi X ，Nagaraja TG ，Cernicchiaro N ... -  《-》