Extended-spectrum beta-lactamase genes of Klebsiella pneumoniae strains in Taiwan: recharacterization of shv-27, shv-41, and tem-116.

Klebsiella pneumoniae causing primary liver abscess (PLA) is emerging. This study identified the beta-lactamases genes of K. pneumoniae isolates in Taiwan. The susceptibilities of beta-lactam antibiotics of 30 K. pneumoniae strains associated with primary liver abscess and 30 noninvasive strains were analyzed. The beta-lactamase genes of randomly selected 24 strains from community-acquired infection and 7 extended-spectrum beta-lactamases (ESBL) strains were identified by PCR and DNA sequencing. Protein expression and the ESBL phenotype of beta-lactamase were determined. All 60 strains were ampicillin resistant and cefotaxime susceptible, whereas no strain was ESBL producing. In the 24 selected strains, shv-1a was found in 14, shv-1 in 7; shv-26, shv-27, and shv-41 were detected in one. However, all of these 24 strains had the tem-116 gene. In 7 ESBL-producing K. pneumoniae strains, shv-5a was found in 5, whereas shv-5 and ctx-m-9 group were detected in 1 strain. Two previously reported ESBL genes, shv-27 and tem-116, as well as a suspected ESBL gene, shv-41, were found in non-ESBL-producing strains. Transformation of these genes conferred ampicillin resistance but not the ESBL-producing phenotype in Escherichia coli. Beta-lactamase protein expression of these strains was further confirmed by western blotting. In conclusion, ESBL is rare in community-acquired K. pneumoniae infection and is not associated with PLA in Taiwan. The shv-5a, shv-5, and ctx-m-9 groups are present in ESBL-producing strains in Taiwan, but shv-27, shv-41, and tem-116 are not ESBL genes.