Pandemic extra-intestinal pathogenic Escherichia coli (ExPEC) clonal group O6-B2-ST73 as a cause of avian colibacillosis in Brazil

Extra-intestinal pathogenic Escherichia coli (ExPEC) represent an emerging pathogen, with pandemic strains increasingly involved in cases of urinary tract infections (UTIs), bacteremia, and meningitis. In addition to affecting humans, the avian pathotype of ExPEC, avian pathogenic E. coli (APEC), causes severe economic losses to the poultry industry. Several studies have revealed overlapping characteristics between APEC and human ExPEC, leading to the hypothesis of a zoonotic potential of poultry strains. However, the description of certain important pandemic clones, such as Sequence Type 73 (ST73), has not been reported in food sources. We characterized 27 temporally matched APEC strains from diverse poultry farms in Brazil belonging to the O6 serogroup because this serogroup is frequently described as a causal factor in UTI and septicemia in humans in Brazil and worldwide. The isolates were genotypically characterized by identifying ExPEC virulence factors, phylogenetically tested by phylogrouping and multilocus sequence type (MLST) analysis, and compared to determine their similarity employing the pulsed field gel electrophoresis (PFGE) technique. The strains harbored a large number of virulence determinants that are commonly described in uropathogenic E. coli (UPEC) and sepsis associated E. coli (SEPEC) strains and, to a lesser extent in neonatal meningitis associated E. coli (NMEC), such as pap (85%), sfa (100%), usp (100%), cnf1 (22%), kpsMTII (66%), hlyA (52%), and ibeA (4%). These isolates also yielded a low prevalence of some genes that are frequently described in APEC, such as iss (37%), tsh, ompT, and hlyF (8% each), and cvi/cva (0%). All strains were classified as part of the B2 phylogroup and sequence type 73 (ST73), with a cluster of 25 strains showing a clonal profile by PFGE. These results further suggest the zoonotic potential of some APEC clonal lineages and their possible role in the epidemiology of human ExPEC, in addition to providing the first description of the O6-B2-ST73 clonal group in poultry.Fundacao de Amparo a Pesquisa do Estado de Sao Paulo - FAPESPUniv Sao Paulo, Dept Pathol, Fac Med Vet & Zootecnia, Sao Paulo, BrazilUniv Sao Paulo, Dept Vet Prevent Med, Fac Med Vet & Zootecnia, Sao Paulo, BrazilUniv Fed Sao Paulo, Dept Microbiol Immunol & Parasitol, Escola Paulista Med, Sao Paulo, BrazilUniv Fed Sao Paulo, Dept Microbiol Immunol & Parasitol, Escola Paulista Med, Sao Paulo, BrazilFAPESP: 05/57500-9-TFAPESP: 11/182046-TFAPESP: 14/11523-7]Web of Scienc

Pandemic extra-intestinal pathogenic <i>Escherichia coli</i> (ExPEC) clonal group O6-B2-ST73 as a cause of avian colibacillosis in Brazil

<div><p>Extra-intestinal pathogenic <i>Escherichia coli</i> (ExPEC) represent an emerging pathogen, with pandemic strains increasingly involved in cases of urinary tract infections (UTIs), bacteremia, and meningitis. In addition to affecting humans, the avian pathotype of ExPEC, avian pathogenic <i>E</i>. <i>coli</i> (APEC), causes severe economic losses to the poultry industry. Several studies have revealed overlapping characteristics between APEC and human ExPEC, leading to the hypothesis of a zoonotic potential of poultry strains. However, the description of certain important pandemic clones, such as Sequence Type 73 (ST73), has not been reported in food sources. We characterized 27 temporally matched APEC strains from diverse poultry farms in Brazil belonging to the O6 serogroup because this serogroup is frequently described as a causal factor in UTI and septicemia in humans in Brazil and worldwide. The isolates were genotypically characterized by identifying ExPEC virulence factors, phylogenetically tested by phylogrouping and multilocus sequence type (MLST) analysis, and compared to determine their similarity employing the pulsed field gel electrophoresis (PFGE) technique. The strains harbored a large number of virulence determinants that are commonly described in uropathogenic <i>E</i>. <i>coli</i> (UPEC) and sepsis associated <i>E</i>. <i>coli</i> (SEPEC) strains and, to a lesser extent in neonatal meningitis associated <i>E</i>. <i>coli</i> (NMEC), such as <i>pap</i> (85%), <i>sfa</i> (100%), <i>usp</i> (100%), <i>cnf</i>1 (22%), <i>kps</i>MTII (66%), <i>hly</i>A (52%), and <i>ibe</i>A (4%). These isolates also yielded a low prevalence of some genes that are frequently described in APEC, such as <i>iss</i> (37%), <i>tsh</i>, <i>omp</i>T, and <i>hly</i>F (8% each), and <i>cvi/cva</i> (0%). All strains were classified as part of the B2 phylogroup and sequence type 73 (ST73), with a cluster of 25 strains showing a clonal profile by PFGE. These results further suggest the zoonotic potential of some APEC clonal lineages and their possible role in the epidemiology of human ExPEC, in addition to providing the first description of the O6-B2-ST73 clonal group in poultry.</p></div

XbaI-PFGE dendrogram generated with the Bionumerics software based on the Dice similarity index indicating the genetic relatedness of 27 ExPEC O6-B2-ST73 strains from poultry.

<p><b>The level of similarity (%) is shown at the top</b>. A, B and C indicate the three pulsotypes. States: PR = Paraná, RS = Rio Grande do Sul, SC = Santa Catarina, SP = São Paulo. VFs = Virulence factor, SUL = Sulfonamides, TET = Tetracycline.</p

Prevalence of virulence markers in 27 strains of APEC O6-B2-ST73.

<p>Prevalence of virulence markers in 27 strains of APEC O6-B2-ST73.</p

Edwardsiella tarda outbreak affecting fishes and aquatic birds in Brazil

Background: Edwardsiella tarda infections are frequent causes of severe outbreaks in the fish farming industry besides representing possible zoonotic risks. However, naturally occurring outbreaks that affect various species besides fishes are seldom described. Aim: To report an outbreak of acute mortality caused by E. tarda affecting multiple species that inhabited a natural pond in the state of São Paulo, Brazil. Materials and methods: Three adult tilapias, three Mallard ducks and one Snow egret were necropsied and subjected to further microbiological tests. Gross and microscopic lesions were documented. The antibiotic susceptibility and phylogenetic similarities among fish and avian strains were also determined. The E. tarda species was confirmed through MALDI-TOF, partial sodB sequencing and phylogenetic analysis. Results: Macroscopical findings between the three species included intestinal dilatation, mucosal hyperaemia and mucous to liquid contents. Common histopathology findings included acute enteritis, increased number of intraepithelial lymphocytes with bacteria adhered to the intestinal epithelium and lymphoid depletion in the spleen. E. tarda was isolated from several organs from all affected species. The phylogeny employing amplified fragment length polymorphism (AFLP) of eleven strains revealed high similarity (>90%) among the isolates regardless of the affected species or sampled organs. Ten isolates of E. tarda showed susceptibility to all tested antibiotics. Conclusions: E. tarda was identified as the cause of death of the species examined. Further studies would be necessary to determine the virulence of these strains and the possible risks regarding public health