Background and Aims: Klebsiella pneumoniae is a major cause of hospital-acquired infections, where biofilm formation and quinolone resistance complicate treatment outcomes. This research examined the occurrence of biofilm formation, plasmid-mediated quinolone resistance (PMQR) determinants, and chromosomal alterations among clinical K. pneumoniae isolates.
Materials and Methods: In this cross-sectional investigation, 120 K. pneumoniae were obtained. Antimicrobial susceptibility and biofilm formation tests carried out using disk diffusion and microtiter plate methods, respectively. Minimum inhibitory concentration (MIC) was determined by the agar dilution approach. Polymerase chain reaction (PCR) and DNA sequencing were carried out to identify resistance- and biofilm-related genes, along with mutations in the gyrA and parC genes. Statistical analysis was performed using SPSS 22.0, and the association between biofilm formation and FQ resistance was evaluated with Fisher’s exact test (p<0.05 considered significant).
Results: The highest resistance was observed against ampicillin (77.5%, 93/120). Biofilm production was observed in 69.2% (n; 83/120). Resistance to ciprofloxacin was seen in 56.7% isolates, and PCR revealed frequent presence of gyrA, parC, qnrS, aac(6′)-Ib-cr, qepA, oqxA, and oqxB genes, with common mutations S83I and D87N in gyrA and S80I and E84V in parC. Biofilm-producing isolates had significantly higher resistance to ampicillin (p=0.001>), imipenem (p=0.037), gentamicin (p=0.045), and ceftazidime (p= 0.003), and fluoroquinolone resistance genes (qepA, oqxB) were more prevalent among them.
Conclusion: This investigation revealed a considerable frequency of PMQR genes and chromosomal alterations in quinolone-resistant K. pneumoniae isolates, highlighting a strong association between biofilm formation and antimicrobial resistance. The outcomes underscore the genetic mechanisms underlying resistance and the difficulties in controlling infections triggered by these strains.