Molecular characterization of extended spectrum beta-lactamases produced by Klebsiella pneumoniae clinical strains from a Tunisian Hospital.

OBJECTIVES: Extended-spectrum β-lactamases are widespread in hospital settings worldwide. The prevalence of ESBL producing Klebsiella pneumoniae (ESBL-KP) strains isolated from patients has recently increased in Tunisia. We conducted this study to determine the prevalence and the genetic characterization of ESBL-KP in a Tunisian Hospital.

PATIENTS AND METHODS: We performed antibiotic susceptibility testing, multiplex PCR, and DNA sequencing analysis on 118 non repetitive K. pneumonia strains isolated during three years, to determine the prevalence and genotypes of ESBL among K. pneumoniae clinical isolates.

RESULTS: Most ESBL-producing K. pneumonia strains were isolated from hospitalized patients, especially in neonatal and pediatric wards. The resistance to other antibiotics was high. Most of the pathogens were isolated from the urinary tract (86.44%). Carbapenems were the most effective antimicrobial agents followed by amikacin and fosfomycin. The rate of blaSHV, blaTEM, and blaCTX-M genes among the isolates was 89, 56.78, and 81.35%, respectively. Sequencing revealed the amplicons encoding TEM-1, TEM-53, TEM-158, SHV-1, SHV-11, SHV-28, CTX-M-15, CTX-M-15-like. The blaCTX-M-15 was the dominant gene among Tunisian isolates, but this was the first report of blaTEM-53 and blaTEM-158 genes in the country.

CONCLUSIONS: Our results confirm the predominance of CTX-M-15 in Tunisia. To our knowledge, this is the first report of TEM-158 and TEM-53 in Tunisia.