Genetic profiling of the tolC component of the acrAB-TolC efflux pump in clinical Klebsiella pneumoniae isolates: a cross-sectional study in Pontianak, Indonesia.

BACKGROUND

Klebsiella pneumoniae is a leading cause of hospital-acquired infections. Its increasing prevalence poses substantial challenges to both hospital and public health systems due to the emergence of multidrug-resistant strains. Understanding the epidemiology of K. pneumoniae and its antimicrobial resistance characteristics may support antimicrobial stewardship and infection control programs. A cross-sectional study was conducted from June to November 2025.

METHODS

A total of 62 isolates underwent phenotypic identification and antimicrobial susceptibility testing using the BD Phoenix system (Becton Dickinson), followed by molecular detection of K. pneumoniae and efflux pump genes. Sanger sequencing was performed on isolates positive for the tolC gene.

RESULTS

Among the isolates, 66.1% were classified as extended-spectrum β-lactamase (ESBL) producers, 6.5% as carbapenem-resistant Enterobacterales (CRE), and 6.5% as both ESBL and CRE producers. Most clinical isolates were resistant to ampicillin, cefazolin, ceftazidime, ceftriaxone, ciprofloxacin, and cefepime. The acrAB and tolC genes were detected in all 62 isolates. One isolate showed a genetic profile similar to that of the K. pneumoniae KP 52.145 strain.

CONCLUSION

This study demonstrated a high prevalence of antibiotic resistance among K. pneumoniae isolates and confirmed the presence of efflux pump genes, including tolC, with observable genetic variability. Further investigation of tolC gene evolution is essential, as these genes play critical roles in antibiotic resistance mechanisms.