Antimicrobial resistance patterns and carbapenemase gene distribution in pediatric Pseudomonas aeruginosa isolates: molecular and epidemiological insights from an Iranian referral center.

BACKGROUND

Antimicrobial resistance in Pseudomonas aeruginosa represents a major challenge in pediatric healthcare, yet molecular epidemiological data from children in the Middle East are limited. This study aimed to characterize antimicrobial resistance patterns, carbapenemase gene profiles, and transmission dynamics in a tertiary pediatric hospital in Iran.

METHODS

We analyzed 110 P. aeruginosa isolates from pediatric patients (December 2023-August 2024) using disk diffusion susceptibility testing, PCR detection of carbapenemase genes (blaIMP, blaKPC, blaNDM, blaOXA, blaSIM, blaSPM, and blaVIM), and RAPD-PCR genotyping. Multivariate logistic regression analysis was used to identify predictors of resistance.

RESULTS

Carbapenem resistance (CR) affected 40.9% of isolates, with 37.3% multidrug-resistant (MDR) and 10.0% extensively drug-resistant. Among CR isolates, blaVIM (68.9%) and blaNDM (55.6%) predominated, with 49.1% harboring multiple carbapenemase genes. Age was a significant predictor of antimicrobial resistance (p < 0.05 for most antibiotics). Children < 5 years demonstrated significantly lower resistance compared to those > 10 years, with the strongest associations observed for fluoroquinolones (ciprofloxacin: AOR = 0.046 (CI: 0.010–0.212), p < 0.001; norfloxacin: AOR = 0.061 (CI: 0.013–0.283), p = 0.002) and some β-lactams (meropenem: AOR = 0.196 (CI: 0.062–0.623), p = 0.021). Gender showed no significant association with resistance across all antibiotics tested (p > 0.05). Gene coexistence was a significant predictor for β-lactams (imipenem: AOR = 1.968 (CI: 1.314–2.946), p = 0.001). RAPD-PCR revealed 23 genetic clusters, with ward-specific clustering patterns suggesting nosocomial transmission, particularly in intensive care units (ICUs).

CONCLUSION

This study demonstrates an alarming burden of carbapenemase-producing P. aeruginosa among Iranian pediatric patients, with age-dependent antibiotic resistance, frequent co-existence of carbapenemase genes suggesting horizontal gene transfer, and ward-specific genetic clustering consistent with nosocomial transmission. These observations underscore the necessity for age-focused therapeutic strategies, intensified ICU surveillance, and targeted antimicrobial stewardship.