Pneumonia-Specific Escherichia coli with Distinct Phylogenetic and Virulence Profiles, France, 2012-2014

Abstract

In a prospective, nationwide study in France of Escherichia coli responsible for pneumonia in patients receiving mechanical ventilation, we determined E. coli antimicrobial susceptibility, phylotype, O-type, and virulence factor gene content. We compared 260 isolates with those of 2 published collections containing commensal and bacteremia isolates. The preponderant phylogenetic group was B2 (59.6%), and the predominant sequence type complex (STc) was STc73. STc127 and STc141 were overrepresented and STc95 underrepresented in pneumonia isolates compared with bacteremia isolates. Pneumonia isolates carried higher proportions of virulence genes sfa/foc, papGIII, hlyC, cnf1, and iroN compared with bacteremia isolates. Virulence factor gene content and antimicrobial drug resistance were higher in pneumonia than in commensal isolates. Genomic and phylogenetic characteristics of E. coli pneumonia isolates from critically ill patients indicate that they belong to the extraintestinal pathogenic E. coli pathovar but have distinguishable lung-specific traits.

Keywords: Escherichia coli; France; Nosocomial infection; antimicrobial resistance; bacteria; pneumonia; respiratory infections; ventilator-associated pneumonia; virulence factors.

Figure

Comparison of Escherichia coli isolates among pneumonia patients with extraintestinal infections, France, 2012–2014, with commensal E. coli (COLIVILLE collection) and E. coli bacteremia isolates (COLIBAFI collection). A) Proportions of E. coli phylogenetic groups and subgroups; B) B2 subgroups, D CGA, and B1 CC87; C) virulence factors; and D) antimicrobial drug resistance. Roman numerals correspond to the B2 subgroup. Correspondence with the Achtman multilocus sequence typing schema is as follows: subgroup I, STc131; subgroup II, STc73; subgroup III, STc127; subgroup IV, STc141; subgroup VI, STc12; subgroup VII, STc14; subgroup IX, STc95 (22). Proportions of subgroups are reported as fractions of the respective phylogroups. Asterisks indicate a significant difference between respiratory isolates and strains responsible for bacteremia (COLIBAFI collection) or commensal strains (COLIVILLE collection): *p<0.05; **p<0.005; ***p<0.0005. AMC, amoxicillin/clavulanic acid; AMK, amikacin; AMX, amoxicillin; CTX, cefotaxime; FOX, cefoxitin; OFX, ofloxacin; STc, sequence type complex.