Prevalent resistance mechanisms in isolates from patients with burn wounds

Abstract

Context: Infections are the major cause of morbidity and mortality in burn patients. The Extended Spectrum Beta Lactamase (ESBL), AmpC Beta Lactamase (AmpC), and Metallo-Beta Lactamase (MBL) are the major mediators of antimicrobial resistance in Gram-negative organisms. Methicillin-resistant Staphylococcus aureus (MRSA) are also implicated in causing serious infections in burn patients. Aim: To find the prevalence of ESBL, AmpC, and MBL mediated resistance among Gram-negative organisms and MRSA in Staphylococcus aureus isolates in pus samples obtained from the burn unit. Materials and Methods: ESBL, Amp C, and MBL production was detected using ceftazidime and ceftazidime-clavulanic acid combination disc test, cefoxitin and cefoxitin/boronic acid disk test, and Imipenem-EDTA disk test, respectively. MRSA were screened using oxacillin disc by disc-diffusion technique. Results: High ESBL rate (37%) was seen among Escherichia coli isolates, whereas Acinetobacter cbc exhibited maximum (25%) MBL activity. Among Klebsiella pneumoniae isolates, 20% isolates were ESBL and AmpC producers, whereas no AmpC expression and no co-existence of these enzymes were seen in Escherichia coli. Co-existence of AmpC with MBLs was seen in 9.6% of Pseudomonas aeruginosa isolates while ESBL expression alone was seen in 16.1% of isolates. Conclusions: Drug resistance to antimicrobial agents is a serious threat in burn infection. Early detection of these β-lactamase producing isolates in a diagnostic laboratory could help to avoid treatment failure, as often the isolates producing this enzyme show a susceptible phenotype in routine susceptibility testing.