Antibiotic resistance and molecular characteristics of OXA-48-producing Klebsiella pneumoniae isolates from northeastern Poland.

BACKGROUND

Resistance of Klebsiella pneumoniae to carbapenems is complex and involves the production of carbapenemases. Infections caused by carbapenemase-producing K. pneumoniae represent a significant public health concern due to the limited treatment options available.

OBJECTIVES

The aim of the study was to identify OXA-48-like-producing K. pneumoniae isolates, characterize their multidrug resistance phenotypically and genetically, and classify them into appropriate sequence types (STs).

MATERIAL AND

METHODS

The study was conducted on 3 K. pneumoniae isolates producing OXA-48 carbapenemase obtained from patients hospitalized at the University Hospital of Bialystok, Poland. Identification and antimicrobial susceptibility testing were performed using the automated VITEK 2 system and the broth microdilution method for colistin. Screening for OXA-48 production was performed using a disc containing 30 μg of temocillin. Carbapenemase production was confirmed using the Carba NP test. The presence of the blaOXA-48 gene and genes encoding resistance to quinolones (qnrA, qnrB, qnrD, qnrS) and aminoglycosides (aac(3)-Ia, aac(6')-Ib, ant(4')-IIa, ant(2")-Ia, and aph(3")-Ib) was detected using polymerase chain reaction (PCR). The ST of the isolates was determined based on sequence analysis of conserved housekeeping genes (rpoB, gapA, mdh, pgi, phoE, infB, tonB).

RESULTS

Analysis of antimicrobial susceptibility revealed that the tested strains were resistant to all tested β-lactam antibiotics and exhibited resistance to amikacin, gentamicin, ciprofloxacin, colistin, and trimethoprim-sulfamethoxazole. Polymerase chain reaction analysis revealed the presence of the aac(6')-Ib and aph(3")-Ib genes encoding aminoglycoside-modifying enzymes in all OXA-48-positive strains. Among the genes encoding quinolone resistance, qnrS was detected in all tested isolates. Multilocus sequence typing (MLST) revealed that 2 OXA-48-positive strains belonged to ST15, whereas 1 isolate belonged to ST2193.

CONCLUSIONS

Two sequence types of K. pneumoniae, ST15 and ST2193, producing OXA-48 carbapenemase and exhibiting resistance to aminoglycosides and fluoroquinolones associated with the aac(6')-Ib, aph(3")-Ib, and qnrS genes, respectively, were identified.