A multicenter study of the clonal structure and resistance mechanism of KPC-producing Escherichia coli isolates in Israel

Little is known about the molecular epidemiology of Klebsiella pneumoniae carbapenemase-producing Escherichia coli (KPCEC). We aimed to describe the clonal structure and resistance mechanisms of KPCEC in a multicenter study. The study included 88 isolates from four medical centres in Israel: Tel Aviv Medical Center (n=17), Laniado Medical Center (n=12), Sha'are-Zedek Medical Center (n=38), and Rambam Medical Center (n=21). Twelve (14%) KPCEC were from clinical sites and 86% from surveillance cultures. The clonal structure was studied by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) and was highly diverse, with 79 and 45 different PFGE types and STs, respectively. The most common clones were ST-131 and ST-410, identified in 21 isolates (23%). Dominant clonal complexes (CCs) were CC131 (n=16), CC410 (n=14), CC10 (n=17), and CC-69 (n=6). The bla_KPC-2 and bla_KPC-3 genes were identified in 68 and 20 isolates, respectively. All isolates were non-susceptible to ertapenem; 16 (18%) and 35 (40%) isolates were susceptible (minimal inhibitory concentration ≤1mg/L) to imipenem and meropenem, respectively. Isolates were susceptible to colistin, amikacin, ciprofloxacin, gentamicin, and trimethoprim-sulfamethoxazole in 100%, 87%, 28%, 27%, and 21% of the cases, respectively. bla_KPC-Harbouring plasmids from Tel Aviv Medical Center as well as from six CC-131 isolates from the other centres were studied by Inc and pMLST typing. Sixteen of the 20 bla_KPC2-harbouring plasmids were of identical type, IncN-pMLST ST-15. In conclusion, the clonal structure of KPCEC in Israel is characterized by the predominance of known international extended-spectrum β-lactamase-producing clones and by high intra- and inter-institutional diversity. This suggests that in Israel, clonal spread does not play a major role in the dissemination of KPCEC.