Similarly, in the present study the PFGE profiles of the ST131 isolates showed a similarity level of 61% (Figure 2). All theses ST131 isolates expressed the commonly described virulence genes in ST131 clone including fimH, iha, sat, kpsM, fyuA and iutA, however many of these isolates expressed uncommon genes in this clone including papG allele II (5 isolates), papG allele III (4 isolates), papC (3isolates), afa/draBC (1 isolate) and hylA (2 isolates) (Table 2). Clermont et al have shown that the phylogroup B2 pandemic clone ST131 is highly virulent in a

mouse model, even though it lacks several genes encoding key virulence factors (Pap, Cnf1, HylA) [26]. Nevertheless, the recent findings of Johnson et al point away from ST131 isolates as having higher virulence potential compared with other E. coli types in see more causing invasive infections in a murine sepsis model [27]. Moreover, a recent study have demonstrated that the ST131 clone has a genetic composition that differs from other group B2 strains, and appears to be less

virulent than previously suspected [28]. In fact, in the present study, the non-ST131-group B2 isolates, which were significantly associated to CTX-M-15 ESBLs, had a higher frequency of several genes encoding key virulence factors such selleck chemicals llc as adhesins hra, sfa/foc, papC and papG II and the toxins hylA and cnf1 than had the ST131 isolates (p < 0.01) (Table 3). Surprisingly, unlike most previously published studies, where the ESBL-producing E. coli isolates lacked the toxins hylA and cnf1, in

our collection the group B2 isolates especially those carrying CTX-M had a high frequency of hylA (42.6%) and cnfI (24.5%) (Table 2) [22]. PFGE Molecular motor typing showed polyclonality with sporadic cases and small clusters indicating that the rapid increase of CTX-M-15 producing E. coli isolates could be due to the incorporation of bla CTX-M-15 genes into group B2 clones exhibiting high number of virulence factors as well as ST131. Although ST131 was predominant in 2003-2004, it learn more appeared to be replaced by group B2 strains exhibiting a higher number of virulence factors in 2006 and 2009. The successful spread of CTX-M-15 was reported to be also related to IncF plasmids. The bla CTX-M-15-carrying plasmid studied here were also assigned to incompatibility groups IncF in 72/88 plasmids and rarely to IncL/M, IncI1, IncN and IncHI2. However, unlike other previous reports, bla CTX-M-14 was carried often on non-typeable plasmids (9/15) and not on Inc K or IncF replicons [5]. More than half of the IncF plasmids carrying CTX-M-15 belonged to the single FII replicon type (48/72).