Detection of Antibiotic Resistance Genes among Pseudomonas aeruginosa Strains Isolated from Burn Patients in Iran

Aim: In this study, we evaluated the presence of antibiotic resistance genes among P. aeruginosa strains.

Methodology: From January to September 2012, 100 isolates of P. aeruginosa were collected from burn patients. Antimicrobial susceptibility testing was performed by disk diffusion method. Screening for Metallo-β-lactamases (MBLs) productions were performed by Combination Disk Diffusion Test (CDDT). The frequency of antibiotic resistance encoding genes such as MBLs (IMP, VIM, NDM), ESBLs (CTX-M-15), Amp-C enzyme (CMY), Ambler class A carbapenemases (KPC), Ambler class D β-lactamase (OXA-48), 16S rRNA methylases (armA, rmtB, rmtC, rmtD), Quinolone Resistance Gene (aac(6′)-Ib) and class 1 integron were performed by PCR and Sequencing techniques.

Results: 48(62.33%) of isolates were metallo-beta-lactamase producers. All MBL-producing P. aeruginosawere resistant to antibiotics; while 49% of isolates were resistant to Gentamicin. The aac(6)-Ib, CTX-M-15, int I, CMY, rmtB , rmtD and IMP-1 genes were detected in 57 (74.02%), 48 (62.3%), 48 (62.3%), 7 (9.09%), 11 (14.28%), 9 (11.68%) and 6 (7.7%) isolates respectively, whereas none of them were positive for other genes. The mortality rate due to metallo-β-lactamases-producing P. aeruginosa infection was 5(10.4%).

Conclusions: The prevalence of antibiotic resistance genes producing P. aeruginosa detected in this study is of great concern.