Biofilm Formation and Quinolone Resistance Determinants in Clinical Klebsiella pneumoniae Isolates from Babol, Northern Iran

Daneshmand, Mohsen; Kiani, Masoumeh; Zahedi, Mahlagha; Zare Banadkouki, Abbas; Tayefeh-Arbab, Mohammad Hossein; Pournajaf, Abazar

year 19, Issue 6 (November - December 2025) Iran J Med Microbiol 2025, 19(6): 377-388 | Back to browse issues page

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Daneshmand M, Kiani M, Zahedi M, Zare Banadkouki A, Tayefeh-Arbab M H, Pournajaf A. Biofilm Formation and Quinolone Resistance Determinants in Clinical Klebsiella pneumoniae Isolates from Babol, Northern Iran. Iran J Med Microbiol 2025; 19 (6) :377-388
URL: http://ijmm.ir/article-1-2806-en.html

Biofilm Formation and Quinolone Resistance Determinants in Clinical Klebsiella pneumoniae Isolates from Babol, Northern Iran

Mohsen Daneshmand¹

, Masoumeh Kiani²

, Mahlagha Zahedi³

, Abbas Zare Banadkouki⁴

, Mohammad Hossein Tayefeh-Arbab⁵

, Abazar Pournajaf⁶

1- Student Research Committee, Babol University of Medical Sciences, Babol, Iran
2- Department of Microbiology, Faculty of Medicine, Shahid Sadoughi University of Medical Sciences, Yazd, Iran
3- Department of Pathology, Faculty of Medicine, Shahid Sadoughi University of Medical Sciences, Yazd, Iran
4- Department of Microbiology, Shahid Beheshti University, Tehran, Iran & Quality Control Department of Temad Mfg, Co., Tehran, Iran
5- Infectious Diseases and Tropical Medicine Research Center, Health Research Institute, Babol University of Medical Sciences, Babol, Iran
6- Infectious Diseases and Tropical Medicine Research Center, Health Research Institute, Babol University of Medical Sciences, Babol, Iran , abazar_pournajaf@yahoo.com

Abstract: (388 Views)

Background and Aim: Klebsiella (K.) pneumoniae is a major cause of hospital-acquired infections, where biofilm formation and quinolone resistance complicate the treatment outcomes. This research was aimed to examine the biofilm formation occurrence, plasmid-mediated quinolone resistance (PMQR) determinants, and chromosomal alterations among clinical K. pneumoniae isolates.
Materials and Methods: In this cross-sectional investigation, 120 unique K. pneumoniae isolates were obtained for evaluation. Antimicrobial susceptibility testing and biofilm production examination were conducted through disk diffusion technique and microtiter plate method, respectively. Minimum inhibitory concentration (MIC) was determined by the agar dilution approach. Polymerase chain reaction (PCR) and DNA sequencing were carried out to identify the resistance- and biofilm-related genes, along with mutations in the gyrA and parC genes. The statistical analysis was performed using SPSS 22.0, and the association between biofilm formation and fluoroquinolones (FQ) resistance was evaluated by Fisher’s exact test.
Results: The highest resistance was observed against ampicillin (77.5%, n=93), highlighting its limited therapeutic effectiveness in clinical settings. Biofilm production was observed in 69.2% (n=83). Resistance to ciprofloxacin was seen in 56.7% of 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 difficulties in controlling infections triggered by these strains.