Escherichia coli ST131 causing invasive infections in Romanian patients--a threat we can no longer ignore.

Escherichia coli sequence type ST131 is a major pandemic clonal group of drug-resistant extraintestinal pathogenic E. coli (ExPEC) involved in community-onset and healthcare-associated infections. Thus far, its presence in our area has been paid little attention. This is a preliminary study intended to detect ST131 among 87 clinical isolates retrieved from a larger and unpublished E. coli collection. The study isolates originated from various specimens associated with invasive infections (blood, deep surgical wounds/abscesses, tracheal aspirates, pleural fluid, cerebrospinal fluid, and peritoneal fluid) and were collected between 2010 and 2014. Based on the main inclusion criteria, resistance to extended-spectrum cephalosporins (ESCs) and/or fluoroquinolones (FQs), the isolates were distributed in three categories: isolates with resistance to FQs (20 isolates), to ESCs (8 isolates), and to FQs and ESCs (59 isolates), respectively. Polymerase chain reaction (PCR) -based assays were performed to determine the major phylogenetic groups, to predict the MLST ST131 status, and to detect the bla(CTX-M) content of the ESC-resistant isolates. Overall, the studied isolates derived from phylogenetic groups B2 (42 isolates), A (30 isolates), B1 (11 isolates), and D (4 isolates). Thirty-five isolates, originating from blood (26 isolates), deep wounds (6 isolates), tracheal aspirates (2 isolates), and cerebrospinal fluid (1 isolate), were identified as members of O25b:H4 ST131. Most of them displayed resistance to both ESCs and FQs and harboured group 1 bla(CRX-M) genes. The emergence of ST131 in our region can no longer be ignored. Focused attention to this lineage could reduce infection-related morbidity and antibiotic resistance.