Antimicrobial resistance and molecular typing of Pseudomonas aeruginosa and Acinetobacter baumanii isolated from a burn hospital in Tehran, Iran

Acinetobacter baumanii and pseudomonas aeruginosa are common opportunistic gram-negative bacteria related to hospital-acquired infections. Multidrug resistant microorganisms have emerged as the causes of nosocomial infections worldwide. In this study, we evaluated the existence of blaTEM, blaSHV and blaCTX-M genes among Pseudomonas aeruginosa and Acinetobacter baumannii strains isolated from hospitalized patients in one burn hospital in Tehran, Iran.
From June 2015 to May 2016, 82 isolates were collected from burn patients hospitalized in one burn hospital in Tehran, Iran. A total of 82 isolates of gram-negative, non-fermentative bacilli including pseudomonas aeruginosa (58 isolates) and Acinetobacter baumanii (24 isolates) were tested for susceptibility to selective antibiotics by disk diffusion recommended in CLSI guidelines. All the resistant isolates were subjected to PCR assay for blaTEM, blaSHV, and blaCTX-M genes that encode ESBL.
Resistance to gentamicin was 83%, but resistance to cephalosporins was higher than gentamicin. Out of the 47 pseudomonas aeruginosa resistance isolates, 24 and 9 isolates were CTX-M and TEM procedure, respectively. Among 8 Acinetobacter baumanii isolates that were resistant to all antibiotics, 7 and 1 isolates were CTX-M and TEM producer, respectively. In addition, bla SHV gene was not detected in any of the isolates.
High level of resistance to most antibiotics tested and high prevalence of bla CTX-M gene in this study, indicating the careful detection of antimicrobial resistant strains is needed in order to prevent further resistance to antimicrobial agents in Iran.