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1.
Escherichia coli isolates recovered from 182 fecal specimens from dogs up to five months old from the cities of S?o Paulo and Campinas, SP, Brazil, were examined by polymerase chain reaction (PCR) for several virulence factors and properties. The eae gene was found in 23 isolates of E. coli from 22 dogs, 19 of 146 (13%) from dogs with diarrhea and 3 of 36 (8.3%) from dogs with no diarrhea. Two different eae+ isolates were recovered from one dog with diarrhea. Isolates from two dogs with diarrhea harbored the bfpA gene, and none of the isolates possessed genes for enterotoxins, the EAF plasmid or Shiga toxins. PCR showed that, among the 23 isolates, eight were positive for beta intimin, six for gamma, two for, one for alpha, one for kappa, and five showed no amplification with any of the nine pairs of specific intimin primers used. PCR also showed that the LEE (locus of enterocyte effacement) was inserted in selC in four isolates, likely in pheU in seven isolates, and in undetermined sites in twelve isolates. Fifteen isolates adhered to HEp-2 cells and were fluorescence actin staining (FAS) positive. The predominant adherence pattern was the localized adherence-like (LAL) pattern. The eae-positive isolates belonged to a wide diversity of serotypes, including O111:H25, O119:H2 and O142:H6, which are serotypes that are common among human EPEC. These results confirmed the presence of EPEC in dogs (DEPEC) with and without diarrhea. The virulence factors found in these strains were similar to those in human EPEC, leading to the possibility that EPEC may move back and forth among human and canine populations.  相似文献   

2.
Enteropathogenic Escherichia coli (EPEC) that are known to cause severe diarrhoea in children and young rabbits are well characterized, but there are few reports on the serotypes and intimin (eae) types of EPEC in weaned pigs. Based on detection of the eae gene by PCR and by DNA-hybridisation with LEE specific gene probes, 20 intestinal and 17 faecal eae(+) strains from diarrhoeal (164) and non-diarrhoeal (57) weaned pigs from 13 Hungarian farms, representing 12.8% of diarrhoeal and 14.0% of non-diarrhoeal pigs, were identified. The dominant serotype was O123:H11 (40%) among intestinal, and O108:H9 (23%) among faecal strains. The majority (85%) of the intestinal strains possessed eae-beta and 10% carried eae-gamma gene. In contrast, significantly (p<0.025) fewer faecal strains (53%) harboured the eae-beta gene, and 23% were eae-gamma positive. In vitro adhesion tests of intestinal and faecal eae(+) strains indicated adhesion of 20/37 of the strains to PK15 (porcine kidney) cells while only 3/37 strains adhered to HeLa cells. The ultrastructure of intimate bacterial attachment of representative porcine eae(+) strains to PK15 cells showed no pedestal formation, in contrast to the human EPEC (O127:H5, eae-alpha) strain. In conclusion, the data do not demonstrate a significant role for the eae(+)E. coli in porcine post-weaning diarrhoea, but provide new information on a dominant porcine serotype (O123:H11, eae-beta), and on differences of serotypes and intimin types of porcine eae(+) strains according to their site of isolation. Furthermore there was an indication that the PK15 cell line could be used as a model to study in vitro adherence of eae(+)E. coli of some human and porcine origin.  相似文献   

3.
Faecal samples from 76 diarrhoeic calves belonging to 36 farms located in the Pampas plain, Argentina, were examined for Shiga toxin-producing Escherichia coli (STEC). A total of 15 STEC strains were isolated from 12 (15.8%) calves which came from six different farms. All stx positive strains assayed by PCR were also positives in the Vero cell cytotoxicity test. The majority (60.0%) of the STEC strains carried the stx(1) gene. Twelve (80.0%) of the STEC isolates which belonged to serotypes O5:H- (n = 4), O26:H11 (n = 4), O26:H- (n = 1), O111:H- (n = 2), and O123:H38 (n = 1) were also enterohaemolysin (EHly) positive and carried the gene encoding for intimin (eae). All the stx positive strains were negative for the bfpA gene. Localized adherence to HEp-2 cells were observed in 83.3% of the eae+ STEC strains. STEC belonging to serotype O5:H- showed atypical biochemical properties, including urease production. Urease was also produced by two strains belonging to serotypes O153:H? and non-typeable, respectively. Resistance to three or more antibiotics was observed in 12 (80.0%) of the STEC isolates. Most of the serotypes of STEC recovered in this survey carried virulence traits that are associated with increased human and bovine pathogenicity. The present study shows that highly virulent STEC strains are being shed by diarrhoeic calves from farms located in a high incidence area of human STEC infections.  相似文献   

4.
Domestic farm animals represent an important reservoir of infection for Shiga toxin-producing Escherichia coli (STEC). Nevertheless the bacterial factors required to colonise these hosts are poorly defined. In this study, the prevalence of a recently described fimbrial gene cluster, lpfO113, among human and animal isolates of STEC was investigated. lpfO113 has been shown to play a role in the adherence of STEC O113:H21 to epithelial cells. Here the presence of the lpfAO113 gene (predicted to encode a major fimbrial subunit) was examined by PCR in E. coli of serogroups O157 and O26 isolated from pigs (n=38), cattle (n=10), and humans (n=9). In addition, we tested for several other genetic virulence markers including Shiga toxin (stx), intimin (eae), the translocated intimin receptor (tir), EHEC-hemolysin (ehx) and F18 fimbriae (fedA). Overall 45 of the 57 strains (79%) possessed the lpfAO113 gene as determined by the presence of a 573 bp PCR product. Moreover, there was a close correlation between the presence of the lpfAO113 marker and the absence of the eae gene. lpfAO113 was found in all of pig isolates, suggesting a possible role in colonisation of the porcine host. In addition, several E. coli strains isolated from pigs had two fimbrial gene markers, fedA and lpfAO113. lpfAO113 was not present in strains of E. coli O157:H7 as described previously. Overall these results show that lpfAO113 is widely distributed among eae-negative E. coli isolates and thus may represent an important adherence factor in this group of pathogens.  相似文献   

5.
A total of 178 Escherichia coli isolates from diarrheic and healthy rabbits in the S?o Paulo State (Brazil) were serobiotyped and investigated by PCR for the presence of virulence genes. Among the 90 (50.6%) isolates which possessed the eae gene, 74 were from diarrheic animals and all but one encoded intimin beta. Sixty five (72.2%) of the eae+ isolates had insertion of the locus of enterocyte effacement locus in the pheU locus, 11 (12.2%) in the selC and 14 (15.6%) did not insert in either of these loci. All isolates were negative for genes of the E. coli enterotoxins, Stx1, Stx2, CNF1, CNF2 and EHEC hemolysin. The O132:H2 serotype was dominant, being present in 63 isolates (70%) of the 90 eae+ isolates, and 57 of the 63 isolates of this serotype belonged to biotype 30. PCR detected the gene for AF/R2 fimbriae in 75 (83.3%) of the 90 eae+ isolates. Adherence to HeLa cells was best detected following 6h incubation and a positive fluorescence actin staining (FAS) test was given by 52 isolates. These data show that isolates of E. coli associated with diarrhea in rabbits in Brazil possess the genotype and phenotype typically associated with rabbit enteropathogenic E. coli (EPEC). We conclude that EPEC that possess the eae gene are a common cause of diarrhea in Brazilian rabbit farms and that the pathogenic eae+ AF/R2+ isolates of O132:H2:B30 serobiotype are especially predominant.  相似文献   

6.
This study identified potential virulence markers in 93 eae-positive and 179 eae-negative Shiga toxin-producing Escherichia coli (STEC), isolated from a random sampling of healthy cattle in southwestern Ontario. PCR amplification was used to identify genes for enterohemorrhagic E. coli (EHEC)-hemolysin, the EAF plasmid, and bundle-forming pili (Bfp); adherence to HEp-2 cells and to bovine colonocytes, and the fluorescent actin staining (FAS) test were used to characterize interaction of the bacteria with epithelial cells. The EHEC-hemolysin sequences were detected in 98% of eae-positive isolates compared with 34% of eae-negative isolates. All isolates were negative for EAF and bfp sequences. There was 100% correlation between localized adherence (LA) to HEp-2 cells and the FAS test. Forty-eight (52%) of the eae-positive isolates were LA/FAS-positive, whereas none of the 179 eae-negative isolates was positive in either test. Among the eae-negative isolates, 20 (11%) showed diffuse adherence and 5 (2.8%) showed enteroaggregative adherence to HEp-2 cells. Seventy-three percent of the eae-positive isolates adhered to bovine colonocytes, whereas only 26% of 120 eae-negative isolates that were tested adhered. All 13 O157:H7 isolates were positive for eae and EHEC-hemolysin gene sequences, LA/FAS, and adherence to bovine colonocytes. It is concluded that possession of genes for eae and EHEC hemolysin is correlated with the serotype of STEC, that production of EHEC hemolysin was highly correlated with serotypes implicated in human disease, and that none of the potential markers that were examined can be used to predict the potential virulence of an isolate.  相似文献   

7.
《Veterinary microbiology》1997,54(2):145-153
Nineteen Escherichia coli strains belonging to enteropathogenic (EPEC) serogroups were isolated from calves with diarrhea in Paraná State, Brazil, and studied for virulence markers associated with EPEC or enterohemorrhagic E. coli (EHEC). The 19 isolates belonged to 12 serotypes with isolates of O26:H11, O119:H25 and O114:H− being the most prevalent. Localized adherence (LA) was demonstrated for 37% of the isolates, consisting of all four O26:H11, both O114:H− and one O114:H40 isolates. All the LA strains were positive in the fluorescent-actin staining (FAS) test and possessed attaching-effacing E. coli (eae) sequences, but only O114 strains hybridized with the EPEC adherence factor (EAF) probe. None of the strains produced Shiga-like toxins (Verotoxin). Only the O26:H11 strains hybridized with the EHEC plasmid specific (CVD419) probe and were enterohemolytic, properties associated with EHEC strains. This investigation demonstrates that among the bovine strains isolated only those of serogroup O114 behaved as typical EPEC.  相似文献   

8.
A total of 42 Shiga toxin-producing (STEC) strains from slaughtered healthy cattle in Switzerland were characterized by phenotypic and genotypic traits. The 42 sorbitol-positive, non-O157 STEC strains belonged to 26 O:H serotypes (including eight new serotypes) with four serotypes (O103:H2, O113:H4, O116:H-, ONT:H-) accounting for 38.1% of strains. Out of 16 serotypes previously found in human STEC (71% of strains), nine serotypes (38% of strains) were serotypes that have been associated with hemolytic-uremic syndrome (HUS). Polymerase chain reaction (PCR) analysis showed that 18 (43%) strains carried the stx1 gene, 20 strains (48%) had the stx2 gene, and four (9%) strains had both stx1 and stx2 genes. Of strains encoding for stx2 variants, 63% were positive for stx2 subtype. Enterohemolysin (ehxA), intimin (eae), STEC autoagglutinating adhesin (saa) were detected in 17%, 21%, and 19% of the strains, respectively. Amongst the seven intimin-positive strains, one possessed intimin type beta1 (O5:H-), one intimin gamma1 (O145:H), one intimin gamma2/theta, (O111:H21), and four intimin epsilon (O103:H2). The strains belonged to 29 serovirotypes (association between serotypes and virulence factors). O103:H2 stx1eae-epsilon ehxA, O116:H- stx2, and ONT:H- stx2c were the most common accounting for 29% of the strains. Only one strain (2.4%) of serovirotype O145:H- stx1stx2eae-gamma1ehxA showed a pattern of highly virulent human strains. This is the first study providing characterization data of bovine non-O157 STEC in Switzerland, and underlining the importance of the determination of virulence factors (including intimin types) in addition to serotypes to assess the potential pathogenicity of these strains for humans.  相似文献   

9.
Feces of 70 diarrhoeic and 230 non‐diarrhoeic domestic cats from São Paulo, Brazil were investigated for enteropathogenic (EPEC), enterohaemorrhagic (EHEC) and enterotoxigenic (ETEC) Escherichia coli types. While ETEC and EHEC strains were not found, 15 EPEC strains were isolated from 14 cats, of which 13 were non‐diarrhoeic, and one diarrhoeic. None of 15 EPEC strains carried the bfpA gene or the EPEC adherence factor plasmid, indicating atypical EPEC types. The EPEC strains were heterogeneous with regard to intimin types, such as eae‐θ (three strains), eae‐κ (n = 3), eae‐α1 (n = 2), eae‐ι (n = 2), one eae‐α2, eae‐β1 and eae‐η each, and two were not typeable. The majority of the EPEC isolates adhered to HEp‐2 cells in a localized adherence‐like pattern and were positive for fluorescence actin staining. The EPEC strains belonged to 12 different serotypes, including O111:H25 and O125:H6, which are known to be pathogens in humans. Multi locus sequence typing revealed a close genetic similarity between the O111:H25 and O125:H6 strains from cats, dogs and humans. Our results show that domestic cats are colonized by EPEC, including serotypes previously described as human pathogens. As these EPEC strains are also isolated from humans, a cycle of mutual infection by EPEC between cats and its households cannot be ruled out, though the transmission dynamics among the reservoirs are not yet understood clearly.  相似文献   

10.
The virulence properties of Shiga toxin-producing Escherichia coli (STEC) strains isolated from diarrhoeic and non-diarrhoeic calves were compared. The strains were also tested for O157:H7, O111 and O26 serotypes, using PCR and conventional serotyping methods. E coli strains isolated from 297 faecal samples, from 200 diarrhoeic and 97 non-diarrhoeic calves, were screened by multiplex PCR assay for the stx1, stx2, eae and Ehly virulence genes. STECs were recovered from 8 per cent of diarrhoeic calves and 10.3 per cent of non-diarrhoeic calves. The predominant virulence gene profile was stx1/eae/Ehly (47.3 per cent) among isolates from diarrhoeic calves and eae/Ehly (36.8 per cent) among isolates from non-diarrhoeic calves. Among three tested serogroups, the predominant serogroup was O26 (18.4 per cent), and O157:H7 was not detected. Intimin subtyping by restriction fragment length polymorphism analysis revealed only three intimin subtypes (β, γ and ). A significant difference was observed in the distribution of Int- between two groups. Int- was present in 50 per cent of the isolates from diarrhoeic calves and in 11.1 per cent of the isolates from non-diarrhoeic calves; this difference was statistically significant (P=0.01).  相似文献   

11.
Domestic animals belonging to seven different species (cattle, sheep, dogs, cats, pigs, chicken and goats) were investigated as natural reservoirs for attaching and effacing Escherichia coli (AEEC). For this, 2165 E. coli strains from faeces of 803 animals were examined for the presence of the intimin -(eae) gene as a characteristic of AEEC strains. Ten percent of the animals were found to excrete AEEC, most frequently found in sheep (19.2%) and pigs (17.6), followed by cattle (10.4%), dogs (7.2%), cats (6.5%) and poultry (2.3%). The 97 AEEC strains from animals were grouped into 44 serotypes. Only four E. coli serotypes (O2:H8, O26:[H11], O109:[H25] and O145:[H28] were found in more than one animal host species. AEEC O26:[H11] strains were most frequently isolated (13.4%) being present in cattle, poultry, pigs and sheep. A search for virulence markers associated with enterohemorrhagic E. coli (EHEC) revealed Shiga-toxin genes in three (3.1%) AEEC strains from sheep. Bundle forming pili genes as a trait of typical enteropathogenic E. coli (EPEC) were detected in four (4.1%) strains from dogs and cats. The remaining 90 AEEC strains were classified as atypical EPEC. Typing of intimin genes revealed intimin beta being present in 51.5% of the strains, followed by intimins theta (23.7%), epsilon (6.2%), kappa (5.2%), zeta (5.2%), alpha, eta and iota (each 1.0%). Our data indicate that domestic animals and pets constitute an important natural reservoir of AEEC strains, and some of these (O26:[H11], O103:H2, O128:H2, O145:[H28] and O177:[H11]) are known to occur as pathogens in humans.  相似文献   

12.
Several outbreaks of Escherichia coli O157 have been reported in petting zoos, resulting in hospitalization of many children. At present, no standard procedure has been adopted to monitor the presence of enterohemorrhagic E. coli (EHEC) or Shiga-toxin-producing E. coli (STEC) in petting zoo animals. Direct detection of these strains from rectal swabs of animals in petting zoos was developed and obviated the need to culture the organisms. DNA extracted from bacteria in the swabs was tested for the presence of wecA gene specific for E. coli by polymerase chain reaction (PCR). The wecA positive samples were further tested for Shiga-toxin genes stxl and stx2, and the intimin eae by multiplex PCR and for the presence of O157 and H7. Swabs (n=104) from 15 animal species in a petting zoo were tested; 7 goats and 3 cows were found to carry STEC. The method is rapid and convenient for monitoring potentially pathogenic E. coli in petting zoo animals.  相似文献   

13.
Two hundred and fifty Escherichia coli isolates from diarrhoeic and healthy piglets were serotyped and tested for the presence of virulence genes for fimbriae, intimin, heat-labile (LT) and heat-stable (STa and STb) enterotoxins, Stx toxins, and enteroaggregative heat-stable 1 (EAST1) enterotoxin by polymerase chain reaction (PCR). Although 220 isolates from diarrhoeic piglets belonged to 43 O serogroups and 77 O:H serotypes, 60% were of one of the 10 serogroups O2, O8, O15, O54, O84, O101, O141, O147, O149 and O157, and 60% belonged to only 10 serotypes (O8:H-, O54:H-, O84:H7, O101:H-, O141:H-, O141:H4, O147:H-, O149:H10, O163:H-, and ONT:H-). PCR showed that 79% of 220 isolates carried genes for at least one of the virulence factors tested. The gene encoding for EAST1 was the most prevalent (65%) followed by those encoding for STb (49%), LT (42%), STa (13%), and Stx2e (4%). Eighty-three (38%) of the 220 E. coli isolates carried the gene for F4 (K88), whereas genes for F18, F5 (K99), F41, F6 (P987), F17, and intimin (eae) were detected in 9%, 3%, 3%, 3%, 1%, and 3%, respectively. Seropathotype O149:H10:F4:LT/STb/EAST1 (70 isolates) was the most common, representing 32% of isolates. Pulsed-field gel electrophoresis (PFGE) analysis with XbaI of 15 O149:H10 representative isolates from diarrhoeic piglets distinguished 14 types. The 15 isolates exhibited a wide variability of distinct restriction patterns though all belonged to the same serotype (O149:H10), and all but one showed identical virulence determinants (F4, LT, STb, and EAST1). Among 30 isolates from healthy piglets only two virulence genes were detected: EAST1 (26%) and eae (17%). In total, 12 isolates were positives for the eae gene: five isolates had intimin beta1, four possessed intimin theta and three showed intimin type xiB. This is believed to be the first study describing the presence of intimin type xiB in E. coli of porcine origin.  相似文献   

14.
Strains of Escherichia coli from 101 healthy and 114 diarrheic calves were screened by PCR for the eae (intimin) gene and Shiga toxin genes (stx). Each eae+ and eae/stx+ strain was examined for antimicrobial susceptibility, enterohemolysin activity, and the somatic O antigen was determined. An immunoassay was used to detect Shiga toxin antigens for the eae/stx+ E. coli. Significantly more (p = 0.005) of the healthy calves carried eae+ and eae/stx+ E. coli in their feces when compared to strains from diarrheic calves. Moreover, Shiga toxin antigens were detected significantly more (p = 0.001) often among the eae/stx+ strains from healthy calves when compared to eae/stx+ strains from diarrheic calves. However, significantly more (p = 0.001) of the eae+ and eae/stx+ strains from diarrheic calves were resistant to at least one of the antimicrobials tested, and the strains from diarrheic calves had a significantly (p = 0.05) higher rate of antimicrobial resistance to at least two different antimicrobial classes. No significant difference (p> or =0.05) was detected among the eae+ and eae/stx+ strains from healthy and diarrheic calves for enterohemolysin production. Serogroups O-negative, O5, O26, and O111 were predominate among both healthy and diarrheic calves.  相似文献   

15.
PROBLEM ADDRESSED: Shiga toxin-producing Escherichia coli (STEC), have emerged as food poisoning pathogens which can cause severe diseases in humans. OBJECTIVE: The aim of this study was to determinate the serotypes and virulence genes of STEC strains isolated from sheep in Spain, with the purpose of determining whether sheep represent a potential source of STEC pathogenic for humans. METHODS AND APPROACH: Faecal swabs obtained from 697 healthy lambs on 35 flocks in Spain during the years 2000 and 2001 were examined for STEC using phenotypic (Vero cells) and genotypic (PCR) methods. RESULTS: STEC O157:H7 strains were isolated from seven (1%) animals in six flocks, whereas non-O157 STEC strains were isolated from 246 (35%) lambs in 33 flocks. A total of 253 ovine STEC strains were identified in this study. PCR showed that 110 (43%) strains carried stx(1) genes, 10 (4%) possessed stx(2) genes and 133 (53%) both stx(1) and stx(2). Enterohaemolysin (ehxA) and intimin (eae) virulence genes were detected in 120 (47%) and in 9 (4%) of the STEC strains. STEC strains belonged to 22 O serogroups and 44 O:H serotypes. However, 70% were of one of these six serogroups (O6, O91, O117, O128, O146, O166) and 71% belonged to only nine serotypes (O6:H10, O76:H19, O91:H-, O117:H-, O128:H-, O128:H2, O146:H21, O157:H7, O166:H28). A total of 10 new O:H serotypes not previously reported in STEC strains were found in this study. Seven strains of serotype O157:H7 possessed intimin type gamma1, and two strains of serotype O156:H- had the new intimin zeta. STEC O157:H7 strains were phage types 54 (four strains), 34 (two strains) and 14 (one strain). CONCLUSIONS: This study confirms that healthy sheep are a major reservoir of STEC pathogenic for humans. However, because the eae gene is present only in a very small proportion of ovine non-O157 STEC, most ovine strains may be less pathogenic.  相似文献   

16.
In this study, multiplex PCR was employed to investigate the virulence factors of Escherichia coli strains isolated from 60-day-old calves. Faecal samples were collected from 54 calves at 12 dairy farms in the state of Minas Gerais, Brazil. A total of 156 isolates were obtained after culture and microbiological isolation and were tested by multiplex PCR for the presence of genes encoding toxins (Stx1, Stx2 and STa) and adherence factors (intimin, F41 and F5). Seventy of 156 isolates were positive for at least one virulence factor: ten (14.3?%) from diarrhoeic animals and 60 (85.7?%) from healthy calves. The virulence markers identified were: Stx1 (82.8?%), eae (24.3?%), F41 (11.4?%), F5 (10?%), STa (4.28?%) and Stx2 (4?%). In diarrhoeic animals, Stx1 (70?%) and F41 (30?%) were identified, while Stx1 (83.3?%), eae (28.3?%), F41 (8.3?%), F5 (11.6?%), STa (5?%) and Stx2 (1.6?%) were detected in isolates from healthy calves. Mixed infections with pathotypes Shiga toxin-producing E. coli (STEC)/enteropathogenic E. coli, STEC/enterohaemorrhagic E. coli and STEC/other (eae/F5, Stx1/STa) were detected in five healthy calves. Pathogenic E. coli were identified in 59.26?% of all calves and on 75?% of the dairy farms studied, not only in diarrhoeic (five of six) but also in healthy calves (27 of 48), which demonstrates the importance of this agent in the aetiology of diarrhoea in calves in the state of Minas Gerais.  相似文献   

17.
To obtain microbiological data from rabbits at slaughter, 500 fecal samples and 500 carcasses samples were examined. All samples tested negative for Listeria and Salmonella. Campylobacter were detected in two fecal samples. Of the 500 fecal samples, 45.8% tested positive for eae (intimin), 1.2% for stx (Shiga toxin), and 1.8% for both eae and stx. By colony hybridization, 56 eae positive Escherichia coli strains were isolated. Among them, 27 strains (48.2%) were of the serotypes O178:H7 and O153:H7, whereas 15 strains (26.8%) belonged to a serogroup that has not yet been described (O(CB10681):H7). All strains possessed intimin beta1 and the translocated intimin receptor (tir) capable of being tyrosine phosphorylated. None of the strains harbored the genes for Shiga toxins, EAST1 (astA), bundlin (bfpA), or the EAF plasmid. Slaughter rabbits therefore constitute a reservoir for certain atypical enteropathogenic Escherichia coli. On rabbit carcasses, average total bacterial counts accounted for 3.3 log CFU cm(-2). Enterobacteriaceae and coagulase positive staphylococci (CPS) were detected on 118 (23.6%) and 153 (30.6%) carcasses, respectively. Enterobacteriaceae and CPS counts of positive samples were mainly <1.5 log CFU cm(-2). Among 153 selected CPS isolates, 98.7% were identified as Staphylococcus aureus. None of the 151 isolated strains harbored the gene for methicillin resistance (mecA). Genes for staphylococcal enterotoxins (SE) were detected in 102 strains. The combinations of seg and sei (53 strains) and sed, seg, sei, and sej (27 strains) dominated.  相似文献   

18.
Shiga toxin-producing Escherichia coli (STEC) strains isolated from healthy cattle (O111:NM, seven strains; O111:H8, three strains) in Brazil were studied and compared to previously characterized human strains in regard to their phenotypic and genotypic characteristics to evaluate their pathogenic potential. Most bovine STEC O111 strains were isolated from dairy calves, and strains with genotypes stx1 alone and stx1/stx2 (variant stx2) occurred in different regions. Irrespective of the stx genotype, all strains were positive for eae theta, alpha variants of tir, espA and espB, and for ler, qseA, iha, astA and efa1 genes. Only one strain was negative for EHEC-hlyA and all strains were negative for iha, saa and espP genes and for EAF and bfpA, genetic markers of EPEC. Except for the presence of stx2, bovine strains showed the same profile of putative virulence genes found among the human strains. Similar biochemical behavior was identified among the strains analysed. Two bovine STEC strains produced the localized adherence (LA) phenotype in 6-h tests with Caco-2 (human enterocyte) cells. Intimate attachment (judged by the FAS test) was found in 9 out of 10 bovine strains as it was observed for the human STEC strains. RAPD-PCR analysis showed two distinct RAPD groups among the STEC O111 strains examined. Despite the relative low frequency of STEC O111 strains recovered from cattle no differences in their pathogenic potential were observed compared to some strains isolated from human diarrhea, suggesting that healthy cattle may be a potential source of infection for humans in Brazil.  相似文献   

19.
The importance of latent zoonoses has increased in recent years in view of foodborne diseases: (i) the "healthy" animal repesents a reservoir for specific pathogens; () no pathological-anatomical changes in the carcass and its organs show the presence of these pathogens; and (iii) these pathogens may enter the food chain via hygienic weak points in the slaughtering process. To estimate the risks involved and to take appropriate measures, analysis of the slaughtering process should be complemented by collecting data relating to the carriage of the animals of latent zoonotic pathogens. From October 2004 to June 2005, fecal samples from 630 slaughtered sheep were enriched and then examied by IMS technique and by PCR to assess the prevalence of E. coli O157 (OE). Seven samples (1.1%), distributed throughout the whole examination period, were found to be positive. To assess the potential pathogenicity for humans, E. coli O157 strains were isolated by colony hybridization and further characterized. The isolated strains fermented Sorbitol, showed four different H tys (H7, H12, H38, H48), and were all negative for stx. One O157:H7 strain harbored the gene for intimin (eae) in combination with ehxA, and paa. In consequence, the potential health hazard from sheep meat related to O157 STEC seems current not to be of particular importance in Switzerland. Results emphasize the fact that E. coli O157 are not always STEC but may belong to other pathotypes as nontraditional EPEC.  相似文献   

20.
In the autumn of 1995 the first outbreaks of enterohemorrhagic Escherichia coli O157:H7 including ca 100 human cases were reported in Sweden. From outbreaks in other countries it is known that cattle may carry these bacteria and in many cases is the source of infection. Therefore, the present study was performed to survey the Swedish bovine population for the presence of verotoxin-producing E. coli (VTEC) of serotype O157:H7. Individual faecal samples were collected at the 16 main Swedish abattoirs from April 1996 to August 1997. Of 3071 faecal samples, VTEC O157 were found in 37 samples indicating a prevalence of 1.2% (CI95% 0.8-1.6). All 37 isolates carried genes encoding for verotoxin (VTI and/or VT2), intimin, EHEC-haemolysin and flagellin H7 as determined by PCR. Another 3 strains were of serotype O157:H7 but did not produce verotoxins. The 37 VTEC O157:H7 strains were further characterised by phage typing and pulsed-field gel electrophoresis. The results clearly show that VTEC O157:H7 is established in the Swedish bovine population and indicate that the prevalence of cattle carrying VTEC O157:H7 is correlated to the overall geographical distribution of cattle in Sweden. Results of this study have formed the basis for specific measures recommended to Swedish cattle farmers, and furthermore, a permanent monitoring programme was launched for VTEC O157:H7 in Swedish cattle at slaughter.  相似文献   

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