Phylogeny, sequence-typing and virulence profile of uropathogenic Escherichia coli (UPEC) strains from Pakistan

Escherichia coli lineage ST131 predominates across various spectra of extra-intestinal infections, including urinary tract infection (UTI). The distinctive resistance profile, diverse armamentarium of virulence factors and rapid global dissemination of ST131 E. coli makes it an intriguing pathogen. However, not much is known about the prevalence and genetic attributes of ST131 lineage in Pakistan. We estimated prevalence and genetic attributes of E. coli ST131 isolates causing UTI among 155 randomly selected samples. Samples were analyzed for phylogenetic grouping, O-typing and fum C/ fim H typing. Isolates were further tested for the ESBL and virulence factors using PCR. Overall, 59% of the UPEC isolates belonged to the phylogenetic group B2, followed by D = 28%, B1 = 8% and A = 5%. Among 18 different Sequence-types, ST131 was the dominant lineage ( n = 71; 46%) out of which 72% of the isolates were assigned to the phylogenetic group B2, while 61% adhered to the serogroup O25b. Fum C/ fim H typing confirmed 49% of the ST131 as H30 sub-types. In this study, significant numbers of the identified ST131 isolates were MDR and 42% showed ESBL phenotypes, out of which 37% carried bla - CTX-M-15 . Moreover, different virulence factors were detected in following percentages: fim H,155(100%), iut A 86 (55%), feo B 76 (49%), pap C 75 (48%), papGII 70 (45%), kpsMTII 40 (26%), pap EF 37 (24%), fyu A 37 (24%), usp 22 (14%), pap A 20 (13%), sfa/foc 20 (13%), hly A 18 (12%), afa 15 (10%), cdt B 11 (7%), papGI 6 (4%), papGIII 6 (4%), kpsMTIII 4 (3%) and bma E2 (1%). Conclusively, this study provides important insight into the genetic and virulence attributes of pandemic MDR ST131 strains involved in UTIs. It also highlights higher prevalence of ST131-O25b-H30 UPEC isolates in patients, which was previously unreported from this part of globe.