Clonal replacement of meticillin-resistant Staphylococcus aureus during repeated outbreaks in a long-term care facility.

Meticillin-resistant Staphylococcus aureus (MRSA) is common among residents of long-term care facilities (LTCFs). Analysing the spa types of 22 isolates, mostly bloodstream infections (BSI), revealed five temporally distinct clonal outbreaks occurring in one ward of our local LTCF between 2012 and 2019. Each clone caused episodes of BSI for several months until replaced by another clone. A high MRSA carriage rate of 32% among healthcare workers in this ward was documented during the investigation of the 2019 outbreak. Clonal replacement of MRSA and the role of healthcare workers in transmission are discussed.

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 blaKPC-2 and blaKPC-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 ≤1 mg/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. blaKPC-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 blaKPC2-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 ß-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.