High prevalence of extended-spectrum β-lactamases and plasmid-mediated AmpC β-lactamases in Enterobacteriaceae isolated from long-term care facilities in Korea

The aim of this study was to investigate for the first time the prevalence and types of extended-spectrum β-lactamase (ESBL) and plasmid-mediated AmpC β-lactamase (PABL) in Enterobacteriaceae in Korean long-term care facilities (LTCFs). ESBL rates were 45.3% (72/159) in Escherichia coli and 42.7% (50/117) in Klebsiella pneumoniae. In E. coli, CTX-M-28, the most prevalent ESBLs, was identified for the first time in Korea in 44 isolates. In K. pneumoniae, SHV-12 was found in 27 isolates (52.9% of ESBLs), among which 25 isolates also contained SHV-11. Twenty-seven isolates had SHV and CTX-M β-lactamase simultaneously. PABL genes were detected in 39.3% (46/117) of K. pneumoniae and 3.1% (5/159) E. coli. In E. coli, DHA-1(3), CMY-2(1), and CMY-6(1) were detected, whereas in K. pneumoniae, only DHA-1 was detected. Among the PABL-producing organisms, 80.0% (E. coli) and 52.2% (K. pneumoniae) simultaneously produced ESBLs. In conclusion, LTCF residents in Korea have a very high prevalence of E. coli and K. pneumoniae producing ESBLs, PABLs, or both, and the genotypes of ESBL and PABL were identical with those found in general hospitals.