Phylogenetic group B2 Escherichia coli strains from the bowel microbiota of Pakistani infants carry few virulence genes and lack the capacity for long-term persistence

Abstract

Escherichia coli strains of phylogenetic group B2 obtained from Western human hosts are enriched in virulence-associated genes and have a superior capacity to persist in the colonic microbiota. Here, E . coli strains from 22 infants born in Pakistan whose rectal flora was sampled regularly over the first 6 months of life were examined. B2 strains did not carry the virulence-associated genes sfaD/E, papC, neuB or hlyA more often than strains of other phylogenetic groups. B2 origin was not associated with persistence in the bowel microbiota. As compared with B2 strains from Swedish infants, Pakistani B2 strains carried significantly less often the virulence genes fimH (p 0.04), papC (p 0.02), papG class III (p 0.01), sfaD/E (p < or =0.0001), neuB (p < or =0.0001), and hlyA (p 0.005), and also the high-pathogenicity island (p < or =0.0001). A minority of Pakistani B2 strains belonged to recognized uropathogenic O-groups, which are common among 'Western' B2 strains. Thus, extra-intestinal pathogenicity may be the foremost characteristic of B2 strains colonizing Western populations.

Diversity, transmission and persistence of Escherichia coli in a cohort of mothers and their infants

“…This is in accordance with an earlier study in Swedish infants where B2 strains were found to be most prevalent and the authors argued that increased virulence factor carriage by B2 strains may be a contributing factor (Nowrouzian et al ., 2005; 2006). However, strain dominance in infant guts show geographical variation and B2 strains were not found to be the main colonizer group in Pakastani infants (Nowrouzian et al ., 2009). Overall, the global average distribution of phylogenetic groups in humans in the literature shows group A (40.5%) to be the most predominant and that B2 (25.5%) is subdominant (Tenaillon et al ., 2010).…”

Worldwide Phylogenetic Group Patterns of Escherichia coli from Commensal Human and Wastewater Treatment Plant Isolates

“…Previous research has shown that phylogroup distribution varied across locations. The observed differences were attributed to differences in climate, living area, and feeding habits (Escobar-Páramo et al, 2004 ; Gordon et al, 2005 ; Nowrouzian et al, 2005 , 2009 ; Karami, 2007 ; Pallechi et al, 2007 ; Vinue et al, 2008 ; Bartoloni et al, 2009 ; Hannah et al, 2009 ; Bailey et al, 2010b ; Li et al, 2010 ; Nicolas-Chanoine et al, 2013 ). However, no formal statistical framework was used to test the effect of these parameters in phylogroup distribution.…”

“…To this end, we compiled data from the literature that used the Clermont classification (Clermont et al, 2000 ), to find out if any phylogroup pattern might be related to climate, feeding habits, living area, and/or geographic location. Several studies compared Clermont phylogroups with climate (Escobar-Páramo et al, 2004 ; Gordon et al, 2005 ; Li et al, 2010 ), living area (Nowrouzian et al, 2005 , 2009 ; Karami, 2007 ; Pallechi et al, 2007 ; Vinue et al, 2008 ; Bartoloni et al, 2009 ; Hannah et al, 2009 ; Bailey et al, 2010b ; Nicolas-Chanoine et al, 2013 ), and feeding habits (Gordon et al, 2005 ), however only qualitative differences had been reported and none of the studies had formally tested the observed differences.…”

Phylogeny, Sequence-typing and virulence profile of uropathogenic E. coli (UPEC) strains from Pakistan

“…Interestingly however, another study conducted in Pakistan reported that only 12% of the strains belonged to phylogenetic group B2. These findings suggest that prevalence of phylogenetic group B2 may vary across different regions [29].…”

“…These genes include P-fimbriae, S-fimbriae, haemolysin, aerobactin, K1 and K5 antigens and capsular antigen genes [30,31]. A previous report focusing on UPEC, in Pakistan described prevalence of various VF genes, including hlyA, sfaDE, papC,cnf1, eaeAand afaBC [29] While another study conducted on rectal flora isolates of Pakistani children confirmed that virulence factors such as S-fimbriae, haemolysin, K-1 antigens and class III PapGadhesins are either very rare or completely absent [29]. Among UPEC strains of phylogenetic group B2 wide range of the virulence factors including genes for adhesins (fimH 100%, papA13%, papC 47%, papEF 21% papGI 3%, papGII40%,papGIII 4%, sfa/foc14%, afa 11%, bmaE 1%), toxins (hlyA 7%, cdtB 7%) iron acquisition system (iutA 57%, feoB43%, fyuA 23%) capsular proteins (kpsMTII 26%, kpsMTIII3%) and uropathogenic specific protein (usp 14%) were detected.…”