Resistance to Serum Complement,iss, and Virulence of Avian Escherichia coli

Control of avian colibacillosis is hampered by lack of easily identifiable markers for virulent Escherichia coli. Resistance to serum complement appears to be a widespread trait of virulent avian E. coli, suggesting that bacterial factors promoting survival in serum may be useful in discriminating between virulent and avirulent isolates. Such distinguishing factors may prove useful in diagnostic protocols or as targets in future colibacillosis control protocols. Interestingly, the factors responsible for resistance to complement differ in the E. coli isolated from mammalian and avian hosts, which may reflect differences in the nature of avian and mammalian colibacillosis. In some cases, genetic determinants for serum complement resistance in avian E. coli are found on aerobactin- or Colicin V-encoding plasmids. One such gene, iss, first described for its role in the serum resistance associated with a ColV plasmid from a human E. coli isolate, occurs much more frequently in isolates from birds with colibacillosis than in faecal isolates from healthy birds. Efforts to identify the genomic location of iss in a single, virulent avian E. coli isolate have revealed that it occurs in association with several purported virulence genes, all linked to a large conjugative R plasmid. At this time, it is not known whether iss merely marks the presence of a larger pathogenicity unit or is itself a contributor to virulence. Nevertheless, the presence of the complement-resistance determinant, iss, may be a marker of virulent avian E. coli exploitable in controlling avian colibacillosis.     

Serogrouping,phylotyping, and virulence genotyping of commensal and avian pathogenic Escherichia coli isolated from broilers in Hamedan,Iran

In the present study, 100 Avian-Pathogenic Escherichia coli (APEC) isolates from colibacillosis-suspected broilers and 100 Avian Faecal Escherichia coli (AFEC) isolates from healthy broilers in Iran were examined by PCR for confirmation of their serogroups and phylogenetic background, and their association with ten virulence-associated genes (VAG) including fimC, iutA, chuA, sitA, iss, cvaA/B, hylA, stx1, stx2, and yjaA. Serogroups O78, O1, O2 and O18 were the prominent strains including 54 % of the APEC and 23 % of the AFEC strains. At phylotyping, the majority of APEC strains belonged to phylogenetic group E (22 %) while for the AFEC strains, half of the isolates were not assigned to any group but the predominant phylogroup was E (27 %). Virulence genotyping, revealed that the predominant VAGs were iutA (97 %), fimC (87 %) and iss (84 %) among APEC strains, and fimC (95 %), iss (93 %) and sitA (87 %) in AFEC strains. This is the first time that phylogroup E is described as predominant phylogroup among APEC strains also, this is the first report on the presence of the stx1 gene in APEC strains isolated from broilers in Iran. The results of the present study indicate that VAGs are more prevalent in APEC strains belonging to O2 and O78 serogroups, also phylogroups E and D have more frequency of VAGs than other phylogroups. Therefore, the APEC strains belonging to O2 and O78 serogroups and phylogroups E and D probably have more pathogenicity to broilers.     

Pathotyping avian pathogenic Escherichia coli strains in Korea

To examine the genetic background of avian pathogenic Escherichia coli (APEC) that affects virulence of this microorganism, we characterized the virulence genes of 101 APEC strains isolated from infected chickens between 1985~2005. Serotypes were determined with available anti-sera and median lethal doses were determined in subcutaneously inoculated chicks. The virulence genes we tested included ones encoding type 1 fimbriae (fimC), iron uptake-related (iroN, irp2, iucD, and fyuA), toxins (lt, st, stx1, stx2, and vat), and other factors (tsh, hlyF, ompT, and iss). Twenty-eight strains were found to be O1 (2.0%), O18 (3.0%), O20 (1.0%), O78 (19.8%), and O115 (2.0%) serotypes. The iroN (100%) gene was observed most frequently followed by ompT (94.1%), fimC (90.1%), hlyF (87.1%), iss (78.2%), iucD (73.3%), tsh (61.4%), fyuA (44.6%), and irp2 (43.6%). The strains were negative for all toxin genes except for vat (10.9%). All the strains were classified into 27 molecular pathotypes (MPs). The MP25, MP19, and MP10 pathotypes possessing iroN-fimC-ompT-hlyF-iucD-tsh-iss-irp2-fyuA (22.8%), iroN-fimC-ompT-hlyF-iucD-tsh-iss (21.8%), and iroN-fimC-ompT-hlyF-iss (11.9%) genotypes, respectively, were predominant. Redundancy of iron uptake-related genes was clearly observed and some strains were associated with higher mortality than others. Therefore, strains with the predominant genotypes can be used for diagnosis and vaccine.     

Isolation of Escherichia coli from piglets in South Korea with diarrhea and characteristics of the virulence genes

Escherichia coli was isolated from the feces of 122 piglets with diarrhea on 55 farms in Korea. The virulence genes of each isolate were characterized by polymerase chain reaction (PCR). Of the 562 isolates, 191 carried 1 or more of the virulence genes tested for in this study. Of the 191 isolates, 114 (60%) carried 1 or more of the genes for enterotoxigenic E. coli (ETEC) fimbriae F4, F5, F6, F18, and F41 and ETEC toxins LT, STa, and STb, 57 (30%) carried 1 or more of the genes for the Shiga-toxin-producing E. coli (STEC) toxins Stx1, Stx2, and Stx2e, and 21% and 37% carried the gene for enteropathogenic E. coli intimin and for enteroaggregative E. coli toxin, respectively. Collectively, our results indicate that other pathotypes of E. coli as well as ETEC can be strongly associated with diarrhea in piglets. In addition, detection of the genes for Stx1 and Stx2 indicates that pigs are reservoirs of human pathogenic STEC.     

Genotypic Prevalence of the Adhesin Involved in Diffuse Adherence in Escherichia coli Isolates in Pre‐weaned Pigs with Diarrhoea in Korea

A total of 1002 Escherichia coli strains isolated from pre‐weaned pigs with diarrhoea on 1114 swine farms were screened for the presence of the adhesin involved in diffuse adherence (AIDA) gene by polymerase chain reaction (PCR). Escherichia coli isolates that carried AIDA genes were also tested by PCR for the detection of five fimbriae (F4, F5, F6, F18 and F41), heat‐stable (STa, STb) and heat‐labile (LT) enterotoxin, enteroaggregative E. coli heat‐stable enterotoxin 1 (EAST1), and Shiga toxin 2 oedema disease (Stx2e) genes. Twenty‐three (2.3%) of the 1002 E. coli isolates carried the gene for AIDA. Among 23 isolates shown to carry genes for AIDA, three carried the AIDA gene as the only shown virulence factor. Other isolates carried other virulence factor genes in addition to AIDA. Four isolates carried genes for at least one of the fimbrial adhesins and enterotoxins. Sixteen isolates carried genes for enterotoxins only. The AIDA may represent an additional virulence determinant in pre‐weaned pigs with diarrhoea.     

Phylogenetic grouping,epidemiological typing,analysis of virulence genes,and antimicrobial susceptibility of Escherichia coli isolated from healthy broilers in Japan

Background

The aim of our study was to investigate the possible etiology of avian colibacillosis by examining Escherichia coli isolates from fecal samples of healthy broilers.

Findings

Seventy-eight E. coli isolates from fecal samples of healthy broilers in Japan were subjected to analysis of phylogenetic background, virulence-associated gene profiling, multi-locus sequence typing (MLST), and antimicrobial resistance profiling. Phylogenetic analysis demonstrated that 35 of the 78 isolates belonged to group A, 28 to group B1, one to group B2, and 14 to group D. Virulence-associated genes iutA, iss, cvaC, tsh, iroN, ompT, and hlyF were found in 23 isolates (29.5%), 16 isolates (20.5%), nine isolates (11.5%), five isolates (6.4%), 19 isolates (24.4%), 23 isolates (29.5%), and 22 isolates (28.2%) respectively. Although the genetic diversity of group D isolates was revealed by MLST, the group D isolates harbored iutA (10 isolates, 71.4%), iss (6 isolates, 42.9%), cvaC (5 isolates, 35.7%), tsh (3 isolates, 21.4%), hlyF (9 isolates, 64.3%), iroN (7 isolates, 50.0%), and ompT (9 isolates, 64.3%).

Conclusions

Our results indicated that E. coli isolates inhabiting the intestines of healthy broilers pose a potential risk of causing avian colibacillosis.     

Extraintestinal pathogenic Escherichia coli in poultry meat products on the Finnish retail market

Background

Extraintestinal pathogenic Escherichia coli bacteria (ExPEC) exist as commensals in the human intestines and can infect extraintestinal sites and cause septicemia. The transfer of ExPEC from poultry to humans and the role of poultry meat as a source of ExPEC in human disease have been discussed previously. The aim of the present study was to provide insight into the properties of ExPEC in poultry meat products on the Finnish retail market with special attention to their prevalence, virulence and phylogenetic profiles. Furthermore, the isolates were screened for possible ESBL producers and their resistance to nalidixic acid and ciprofloxacin was tested.

Methods

The presence of ExPEC in 219 marinated and non-marinated raw poultry meat products from retail shops has been analyzed. One E. coli strain per product was analyzed further for phylogenetic groups and possession of ten virulence genes associated with ExPEC bacteria (kpsMT K1, ibeA, astA, iss, irp2, papC, iucD, tsh, vat and cva/cv) using PCR methods. The E. coli strains were also screened phenotypically for the production of extended-spectrum β-lactamase (ESBL) and the susceptibility of 48 potential ExPEC isolates for nalidixic acid and ciprofloxacin was tested.

Results

E. coli was isolated from 207 (94.5%) of 219 poultry meat products. The most common phylogenetic groups were D (50.7%), A (37.7%), and B2 (7.7%). Based on virulence factor gene PCR, 23.2% of the strains were classified as ExPEC. Two ExPEC strains (1%) belonged to [O1] B2 svg+ (specific for virulent subgroup) group, which has been implicated in multiple forms of ExPEC disease. None of the ExPEC strains was resistant to ciprofloxacin or cephalosporins. One isolate (2.1%) showed resistance to nalidixic acid.

Conclusions

Potential ExPEC bacteria were found in 22% of marinated and non-marinated poultry meat products on the Finnish retail market and 0.9% were contaminated with E. coli [O1] B2 svg+ group. Marinades did not have an effect on the survival of ExPEC as strains from marinated and non-marinated meat products were equally often classified as ExPEC. Poultry meat products on the Finnish retail market may have zoonotic potential.     

Virulence factors and genetic variability of uropathogenic Escherichia coli isolated from dogs and cats in Italy

In this study, the association between virulence genotypes and phylogenetic groups among Escherichia (E.) coli isolates obtained from pet dogs and cats with cystitis was detected, and fingerprinting methods were used to explore the relationship among strains. Forty uropathogenic E. coli (UPEC) isolated from dogs (n = 30) and cats (n = 10) in Italy were analysed by polymerase chain reaction (PCR) for the presence of virulence factors and their classification into phylogenetic groups. The same strains were characterized by repetitive extragenic palindromic (REP)- and enterobacterial repetitive intergenic consensus (ERIC)-PCR techniques. We found a high number of virulence factors such as fimbriae A, S fimbriae (sfa) and cytotoxic necrotizing factor 1 (cnf1) significantly associated with phylogenetic group B2. We demonstrated a high correlation between α-hemolysin A and pyelonephritis C, sfa, and cnf1 operons, confirming the presence of pathogenicity islands in these strains. In addition, UPEC belonging to group B2 harboured a greater number of virulence factors than strains from phylogenetic groups A, B1, and D. REP- and ERIC-PCR grouped the UPEC isolates into two major clusters, the former grouping E. coli strains belonging to phylogenetic group B2 and D, the latter grouping those belonging to groups A and B1. Given the significant genetic variability among the UPEC strains found in our study, it can be hypothesized that no specific genotype is responsible for cystitis in cats or dogs.     

Population structure and virulence content of avian pathogenic Escherichia coli isolated from outbreaks in Sri Lanka

Avian pathogenic Escherichia coli (APEC) causes economically significant infections in poultry. The genetic diversity of APEC and phylogenetic relationships within and between APEC and other pathogenic E. coli are not yet well understood. We used multilocus sequence typing (MLST), PCR-based phylogrouping and virulence genotyping to analyse 75 avian E. coli strains, including 55 isolated from outbreaks of colisepticaemia and 20 from healthy chickens. Isolates were collected from 42 commercial layer and broiler chicken farms in Sri Lanka. MLST identified 61 sequence types (ST) with 44 being novel. The most frequent ST, ST48, was represented by only six isolates followed by ST117 with four isolates. Phylogenetic clusters based on MLST sequences were mostly comparable to phylogrouping by PCR and MLST further differentiated phylogroups B1 and D into two subgroups. Genotyping of 16 APEC associated virulence genes found that 27 of the clinical isolates and one isolate from a healthy chicken belonged to highly virulent genotype according to previously established classification schemes. We found that a combination of four genes, ompT, hlyF, iroN and papC, gave a comparable prediction to that of using five and nine genes by other studies. Four STs (ST10, ST48, ST117 and ST2016) contained APEC isolates from this study and human UPEC isolates reported by others, suggesting that these STs are potentially zoonotic. Our results enhanced the understanding of APEC population structure and virulence association.     

Antibiogram,virulotyping and genetic diversity of Escherichia coli and Salmonella serovars isolated from diarrheic calves and calf handlers

Antimicrobial resistance profile of E. coli and Salmonella serovars isolated from diarrheic calves and handlers in Egypt is unknown due to the absence of monitoring. Therefore, this study aimed to determine the virulence, genetic and antimicrobial resistance profiles of E. coli and Salmonella serovars associated with diarrhea in calves and handlers in intensive dairy farms in Egypt. A total of 36 bacterial strains (20 E. coli and 16 Salmonella) were isolated from fecal samples of 80 diarrheic Holstein dairy calves (10 E. coli and 13 Salmonella) and hand swabs of 35 handlers (10 E. coli and 3 Salmonella) in two intensive dairy farms in Sharkia Governate in Egypt. E. coli strains belonged to six different serogroups and O114:K90 was the most prevalent serogroup (30%). However, Salmonella strains were serotyped into four different serogroups and S. Kiel was the most prevalent serotype (50%). Thirteen (65%) E. coli isolates were harbouring either stx2, eaeA and/or astA virulence-associated genes. However, stn and spvC virulence genes were detected in 2 (12.5%) and 4 (25%) of Salmonella isolates, respectively. E. coli isolates showed marked resistance to ampicillin (75%), while Salmonella strains exhibited high resistance to amikacin (100%), gentamicin (93.75%) and tobramycin (87.5%). Results of the present study showed that E. coli and Salmonella serovars isolated from diarrheic calves and handlers in intensive dairy farms in Egypt exhibited resistance to multiple classes of antimicrobials, which may pose a public health hazard. Thus, the continuous monitoring of antimicrobial resistance is necessary for both humans and veterinary medicine to decrease the economic losses caused by antimicrobial-resistant strains in animals as well as the zoonotic risk.     

Dynamics of shiga-toxin producing Escherichia coli (STEC) and their virulence factors in cattle

Starting at birth, twenty Holstein calves were housed individually, in groups of five and finally in one large freestall while fecal samples were collected weekly for 25 weeks. From each sample, twenty isolates of Escherichia coli were screened for 6 virulence markers including shiga-toxin 1, 2, intimin, enterohemolysin, the fimbrial antigen efa1 and the adhesin saa. Dynamic models of transmission of E. coli were used to model the transmission of different virulotypes between calves and the loss of the same virulotypes from the calves. It was found that, once E. coli encoding shiga-toxins in combination with enterohemolysin were transmitted and established in a calf, they tended to be eliminated less efficiently compared to E. coli without this combination of virulence markers. It was concluded that the presence of certain combinations of virulence markers coincided with persistence of E. coli in the bovine gastrointestinal tract. In addition, the combinations of stx with either eae or ehxA in E. coli have a greater impact on the loss rates than on the transmission rates.     

Respiratory microbiota of healthy broilers can act as reservoirs for multidrug-resistant Escherichia coli

This study aimed at evaluate the presence and to study characteristics of Escherichia coli in the respiratory system microbiota of healthy broilers. Trachea, air sacs, and lungs of 20 broilers were analyzed at 21 days of age, reared in experimental conditions, without receiving antimicrobials. E. coli strains were isolated and identified using conventional bacteriology through morphological and biochemical characterization. The production of bacteriocin-like substances, the presence of virulence-associated genes (VAGs) of APEC (Avian Pathogenic Escherichia coli) predictors, and the antimicrobial susceptibility were evaluated. E. coli was found in 85 % of the animals (17/20), in the trachea, air sacs or lungs; and it was not found in 15 % of the animals (3/20). A total of 34 isolates were recovered, 13 from the air sacs, 13 from the lungs, and 8 from the trachea, which showed no production of bacteriocin-like substances nor virulence genes associated with APEC. Most isolates, 59 % (20/34), showed resistance to at least one of the tested antimicrobials, and six multiresistant strains were identified. The results demonstrated that strains of E. coli were commensal of the respiratory microbiota, and that they did not present pathogenicity to the host, since there were no clinical signs of disease, macroscopic lesions in the organs of the evaluated broilers, production of bacteriocin-like substances, nor virulence-associated genes considered as predictors of APEC in bacteria. These strains of E. coli were mostly susceptible to antimicrobials. However, the occurrence of multidrug-resistant strains suggests that these animals can act as reservoirs of resistant to antimicrobials E. coli.     

Virulence-associated genes in avian pathogenic Escherichia coli from laying hens in Apulia,southern Italy

1. Escherichia coli isolated from lesions (Avian Pathogenic E. coli?-?APEC) of layer hens affected by colibacillosis and from intestinal contents of clinically-healthy birds (Avian Faecal E. coli?-?AFEC) were serotyped. All the isolates were investigated for the presence of virulence genes to determine which genes were more closely related to those from lesions.

2. A number of different serogroups were detected, O78 being predominant among the isolates from colibacillosis.

3. E. coli isolated from lesions were not linked to a specific pathotype (set of common virulence genes).

4. The presence of the virulence genes, with the exception of astA, was associated more generally with APEC strains.

5. Statistically, genes such as cva/cvi, tsh, iss, irp2 and iucD were more related to isolates from colibacillosis.

6. It is suggested that the detection of these genes in a rapid and inexpensive test for field practitioners could provide useful information about the potential virulence of E. coli isolated in commercial layer flocks.     

Virulence factors in Escherichia coli isolated from calves with diarrhea in Vietnam

This study was conducted to determine the prevalence and characteristics of pathogenic Escherichia (E.) coli strains from diarrheic calves in Vietnam. A total of 345 E. coli isolates obtained from 322 diarrheic calves were subjected to PCR and multiplex PCR for detection of the f5, f41, f17, eae, sta, lt, stx1, and stx2 genes. Of the 345 isolates, 108 (31.3%) carried at least one fimbrial gene. Of these 108 isolates, 50 carried genes for Shiga toxin and one possessed genes for both enterotoxin and Shiga toxin. The eae gene was found in 34 isolates (9.8%), 23 of which also carried stx genes. The Shiga toxin genes were detected in 177 isolates (51.3%) and the number of strains that carried stx1, stx2 and stx1/stx2 were 46, 73 and 58, respectively. Among 177 Shiga toxin-producing E. coli isolates, 89 carried the ehxA gene and 87 possessed the saa gene. Further characterization of the stx subtypes showed that among 104 stx1-positive isolates, 58 were the stx1c variant and 46 were the stx1 variant. Of the 131 stx2-positive strains, 48 were stx2, 48 were stx2c, 11 were stx2d, 17 were stx2g, and seven were stx2c/stx2g subtypes. The serogroups most prevalent among the 345 isolates were O15, O20, O103 and O157.     

Antimicrobial resistance in Escherichia coli isolates from frugivorous (Eidolon helvum) and insectivorous (Nycteris hispida) bats in Southeast Nigeria,with detection of CTX-M-15 producing isolates

Thirty-five Escherichia coli isolates obtained from the liver, spleen and intestines of 180 frugivorous and insectivorous bats were investigated for antimicrobial resistance phenotypes/genotypes, prevalence of Extended-Spectrum beta-lactamase (ESBL) production, virulence gene detection and molecular typing. Eight (22.9 %) of the isolates were multidrug resistant (MDR). Two isolates were cefotaxime-resistant, ESBL-producers and harbored the bla_CTX-M-15 gene; they belonged to ST10184-D and ST2178-B1 lineages. tet(A) gene was detected in all tetracycline-resistant isolates while int1 (n = 8) and bla_TEM (n = 7) genes were also found. Thirty-three of the E. coli isolates were assigned to seven phylogenetic groups, with B1 (45.7 %) being predominant. Three isolates were enteropathogenic E. coli (EPEC) pathovars, containing the eae gene (with the variants gamma and iota), and lacking stx1/stx2 genes. Bats in Nigeria are possible reservoirs of potentially pathogenic MDR E. coli isolates which may be important in the ecology of antimicrobial resistance at the human-livestock-wildlife-environment interfaces. The study reinforces the importance of including wildlife in national antimicrobial resistance monitoring programmes.     

Virulence traits of avian pathogenic (APEC) and fecal (AFEC) <Emphasis Type="Italic">E. coli</Emphasis> isolated from broiler chickens in Algeria

Avian pathogenic E. coli (APEC) is the etiologic agent of avian colibacillosis, the most common disease responsible for chicken morbidity in the world. Although multiple virulence-associated factors were identified, their prevalence in Algeria is still poorly known. In the present research, 92 avian pathogenic E. coli (APEC) isolates were recovered from broilers with clinical signs and lesions of colibacillosis. In addition, 32 E. coli isolates collected from feces of healthy birds (AFEC) were included for comparison. All isolates were investigated by PCR for the presence of a total of 11 virulence-associated genes described for avian pathogenic (iroN, ompT, hlyF, iss, iutA, and fimC) and diarrheagenic E. coli (eae, stx, elt/est, ipaH, and aggR). The sensitivity of 39 APEC isolates to 16 antibiotics was also determined using antimicrobial pretreated microplates. Here, we report that 98% of the examined isolates host at least one of the tested virulence factors. The most prevalent genes in APEC were iutA (90.6%), ompT (86.9%), and iss (85.8%); whereas, iutA (78.1%), fimC (78.1%), and iroN (68.7%) were the highest prevalent genes in AFEC. Our data showed that none of the AFEC isolates harbor any of the tested diarrheagenic genes. Moreover, only elt/est (5.4%), stx (2.1%), and ipaH (2.1%) genes were carried by APEC isolates. We further established that ceftazodime, ceftiofur, mequindox, amoxicillin/clavulanic acid, and meropenem were the most efficient antibiotics against the analyzed APEC isolates. Overall, our findings provide more insights about APEC and AFEC virulence potential in Algeria which could participate in the fight against colibacillosis.     

Antimicrobial resistance of Escherichia coli isolates from canine urinary tract infections

This study determined the antimicrobial resistance profiles of Escherichia coli isolates from dogs with a presumptive diagnosis of urinary tract infection (UTI). Urine samples from 201 dogs with UTI diagnosed through clinical examination and urinalysis were processed for isolation of Escherichia coli. Colonies from pure cultures were identified by biochemical reactions (n=114) and were tested for susceptibility to 18 antimicrobials. The two most frequent antimicrobials showing resistance in Urinary E. coli isolates were oxytetracycline and ampicillin. Among the resistant isolates, 17 resistance patterns were observed, with 12 patterns involving multidrug resistance (MDR). Of the 69 tetracycline-resistant E. coli isolates, tet(B) was the predominant resistance determinant and was detected in 50.9% of the isolates, whereas the remaining 25.5% isolates carried the tet(A) determinant. Most ampicillin and/or amoxicillin-resistant E. coli isolates carried bla_TEM-1 genes. Class 1 integrons were prevalent (28.9%) and contained previously described gene cassettes that are implicated primarily in resistance to aminoglycosides and trimethoprim (dfrA1, dfrA17-aadA5). Of the 44 quinolone-resistant E. coli isolates, 38 were resistant to nalidixic acid, and 6 were resistant to nalidixic acid, ciprofloxacin and enrofloxacin. Chromosomal point mutations were found in the GyrA (Ser83Leu) and ParC (Ser80Ile) genes. Furthermore, the aminoglycoside resistance gene aacC2, the chloramphenicol resistant gene cmlA and the florfenicol resistant gene floR were also identified. This study revealed an alarming rate of antimicrobial resistance among E. coli isolates from dogs with UTIs.     

Identification and detection of three new F17 fimbrial variants in Escherichia coli strains isolated from cattle

F17 fimbriae are produced by pathogenic Escherichia coli involved in diarrhea and septicemia outbreaks in calves and lambs. These proteins result from the expression of four different clustered genes, namely f17A, f17D, f17C and f17G, encoding a pilin protein, a periplasmic protein, an anchor protein and an adhesin protein, respectively. Several variants of f17A and f17G genes have been reported and found genetically associated with typical virulence factors of bovine pathogenic E. coli strains. In this study, a new F17e-A variant, closely related to F17b-A, was identified from a collection of 58 E. coli isolates from diarrheic calves in Iran. While highly prevalent in Iranian F17-producing clinical isolates from calves, this variant was rare among E. coli from a French healthy adult bovine population, suggesting a possible association with virulence. The f17Ae gene was also found in the genome of the Shiga-like toxin variant Stx_1d–producing bovine E. coli strain MHI813, and belonged to a gene cluster also encoding a new F17-G3 variant, which greatly differed from F17-G1 and F17-G2. This gene cluster was located on a pathogenicity island integrated in the tRNA pheV gene. The gene coding for a third new F17f-A variant corresponding to a combination of F17c-A and F17d-A was also identified on the pVir68 plasmid in the bovine pathogenic E. coli strain 6.0900. In conclusion, we identified three new F17-A and F17-G variants in cattle E. coli, which may also have significant impact on the development of new diagnostics and vaccination tools.     

Detection of Shiga Toxin‐Producing Escherichia coli and Enteropathogenic Escherichia coli in Faecal Samples of Healthy Mithun (Bos frontalis) by Multiplex Polymerase Chain Reaction

Faecal samples obtained from 190 healthy mithuns were examined for the presence of Escherichia coli. Total one‐hundred and five E. coli isolates were obtained from these samples, which belonged to 55 different serogroups. These isolates were subjected to multiplex polymerase chain reaction (m‐PCR) for detection of stx1, stx2, eaeA and hlyA genes. Twenty‐three (21.90%) E. coli isolates belonging to 14 serogroups revealed the presence of at least one virulence gene when examined by m‐PCR. Nineteen percent and 2.85% of the mithuns were found to carry Shiga toxin‐producing E. coli (STEC) and enteropathogenic E. coli, respectively. stx1 and stx2 genes were found to be prevalent in 7 (6.67%) and 18 (17.14%) of the isolates respectively, whereas eaeA and hlyA genes were found to be carried by three (2.85% each) isolates. Interestingly, none of the STEC isolates belonged to serogroup O157.     

Virulence factors in Escherichia coli strains isolated from urinary tract infection and pyometra cases and from feces of healthy dogs

The aim of this study was to compare the prevalence of virulence genes in 158 Escherichia coli strains isolated from 51 clinical cases of UTIs, 52 of pyometra and from 55 fecal samples from healthy dogs by PCR. papC was found in 12 (23.5%) strains isolated from UTIs, 19 (36.5%) from pyometra and 10 (18.2%) from feces. papGII was observed in 3 (5.8%) strains from pyometra, and papGIII in 10 (19.6%) from UTIs, 15 (28.8%) from pyometra and 9 (16.4%) from feces. sfaS was detected in 22 (43.1%) strains from UTIs, 24 (46.1%) from pyometra and 19 (34.5%) from feces. hlyA was observed in 17 (33.3%) strains from UTIs, 18 (34.6%) from pyometra and 7 (12.7%) from feces, while cnf-1 was detected in 11 (21.6%) from UTIs, 21 (40.4%) from pyometra and 9 (16.4%) from feces. iucD was observed in 12 (23.5%) strains from UTIs, 9 (17.3%) from pyometra and 1 (1.8%) from feces. usp was found 17 (33.3%) isolates from UTIs and 36 (69.9%) from pyometra.