Abstract:
BACKGROUND
Infections caused by Pseudomonas aeruginosa present a huge treatment challenge due to the high antibiotic resistance. The rapid development of carbapenem resistance is alarming and calls for implementing surveillance measures. This study aimed to detect antibiotic susceptibility of P. aeruginosa isolated from different clinical samples and to detect carbapenem resistance, metallo β-lactamase and also colistin resistance among carbapenem-resistant P. aeruginosa.
MATERIALS AND METHODS
A cross-sectional study with a sample size of 100 clinical isolates of pathologically significant P. aeruginosa collected from patients of all age groups identified by standard methods were included. The prevalence of P. aeruginosa was estimated at 7.15% (95/1566) from a previous study. The sample size was estimated at 102 with a 95% confidence level and a margin of error of 5%. Antimicrobial susceptibility testing was done by the standard Kirby-Bauer disc diffusion method. Metallo β-lactamase detection done by the combined disc test and Modified Hodge test. Carbapenemase gene detection was done by Real-time polymerase chain reaction. Susceptibility to colistin was detected by the Vitek-2 system.
RESULTS
Out of 100 P. aeruginosa isolates, 52% were from pus, 22% respiratory samples,16% urine and 10% from blood respectively. In antimicrobial susceptibility testing, 30% of the strains were multidrug-resistant, 38% of the strains were sensitive and 32% were intermediate. The highest resistance was observed against fluoroquinolones. Carbapenem resistance was observed as imipenem 17 % and meropenem 16 %. Among the carbapenem-resistant P. aeruginosa, 47% of the strains were metallo β-lactamase producers by the phenotypic method. Gene detection for carbapenemase revealed blaNDM to be the most common gene carried by 35.2% of the MBL-positive carbapenem-resistant strains. All the carbapenem-resistant strains were susceptible to colistin.
CONCLUSION
Maximum number of P. aeruginosa was isolated from pus samples. Prevalence of carbapenem resistance was found to be less in our hospital, with a rate of 17%. The highest resistance was observed against fluoroquinolones. Among carbapenamase, blaNDM seems to be the most prevalent gene at 23%, followed by blaIMP at 11%, blaIMP and blaNDM at 5.8%, and blaNDM, blaIMP and blaVIM at 8 % respectively. No strains exhibited resistance against colistin when tested by the Vitek-2 system.
