CTX-M-15 type extended spectrum β-lactamase producing Escherichia coli and Klebsiella pneumoniae: A developing problem in infected outpatients and hospitalised patients in Istanbul, Turkey

Extented-spectrum β-lactamase (ESBL) producing Escherichia coli and Klebsiella pneumoniae were shown to be a significant cause of both community-acquired and hospital-acquired infections worldwide. The aim of this study was to compare the epidemiological feature of CTX-M, TEM and SHV producing pathogenic E. coli and K. pneumoniae strains in outpatients and hospitalised patients. Antimicrobial susceptibilities of 551 E. coli and 62 K. pneumoniae strains isolated as pathogenic bacteria were determined by disc diffusion method and ESBLs were characterised by isoelectric focusing and PCR. ESBL production was found in 17.4% of the E. coli and 33.9% of the K. pneumoniae strains. CTX-M type ESBL production was determined in 94.8% of the E. coli and 81% of the K. pneumoniae strains and their sequence analysis revealed the presence of CTX-M-15. Our ESBL producing strains had an excellent susceptibility to imipenem, meropenem and ertapenem. According to the usage of molecular methods, the epidemiologic character of CTX-M type ESBL producing E. coli and K. pneumoniae was found to be related particularly to the presence of CTX-M-15 in outpatients and hospitalised patients. Prudent usage of extented-spectrum cephalosporins is inevitable to reduce the propagation of multidrug resistant ESBL-producing organisms and additionnaly to succeed in the treatment.