blaOXA, blaSHV-, and blaTEM- extended-spectrum β-lactamases in Gram-negative strains from burn patients in Lahore, Pakistan.

INTRODUCTION

Gram-negative bacterial pathogens are associated with complications of post-burn infections that showed significant association with different genotypic variants of extended-spectrum β-lactamases. In this study, we aimed to determine the distribution of ESBL gene variants among bacterial pathogens from post-burn infections.

METHODOLOGY: Cephalosporin-resistant isolates were collected from Jinnah Burn and Reconstructive Surgery Centre, Lahore. Phenotypic testing: double-disk synergy test, combination disk test, multiplex PCR for blaOXA, blaTEM, and blaSHV genes were performed.

RESULTS

Of the 53.5% cephalosporin-resistant isolates, 50.7% were community-acquired and 49.3% were nosocomial pathogens. Seventy-two percent of post-burn infections were found in males (p-value = 0.92, OR = 1.04). The age of burn victims ranged from 4 to 85 years (mean = 28.9, SD = 15.6). Pseudomonas aeruginosa was most predominant at a rate of 49%. There were 83.3% multidrug-resistant isolates, which showed susceptibility to meropenem, imipenem, and amikacin in 28.7%, 25.3%, and 26% respectively. In phenotypic tests 16% ESBLs detected by the DDST and 14% confirmed by the CDT. Molecular detection proved effective for the detection of 79.7% blaTEM, 37.7% blaOXA, and 18.8% blaSHV isolates. blaTEM genes were confirmed in 18.1% CDT-positive isolates, with 62.6% diagnostic accuracy (95% CI = 54.7-70) and 88% specificity (95% CI = 80.4-93.4).

CONCLUSIONS

The antimicrobial resistance associated with the ESBL-producing Pseudomonas spp. and Enterobacteriaceae is becoming a challenge for the treatment and survival of burn patients. The high rate blaTEM, blaOXA, and blaSHV genes confirm the need to improve the management of burn patients in order to prevent post-burn infections.