Identification of Class-1 Integron and Various Β-Lactamase Classes among Clinical Isolates of Pseudomonas aeruginosa at Children's Medical Center Hospital

Pseudomonas aeruginosa is one of the most important oppor­tunistic pathogens responsible for various types of infections. Children suffer significant morbidity and mortality due to nosocomial infections. The aim of this study was to investigate the presence of Class-1 integron, blaBEL, blaPER, blaKPC, blaVIM, blaIMP and blaOXA-group-1 genes among P. aerugi­nosa isolates at Children''s Medical Center Hospital in Iran and to determine phenotypic evidence of ESBL and MBL production. Antibiotic susceptibility tests were analyzed for 72 P. aeruginosa clinical isolates. Isolates were identified by using biochemical tests and con­firmed by PCR assay for oprL gene. ESBL and MBL producer isolates were identified by phenotypic tests (double disc synergy tests). Detection of β-lactamase genes and class-1 integron were performed by PCR method. All of the isolates were susceptible to ceftazidime / clavulanate, me­ropenem, imipenem and ciprofloxacin. About 83.3% and 16.7% of isolates were resistant to ceftazidime and amikacin respectively. Approximately, 83.3% of isolates were considered as potential ESBL producers. None of the clinical isolates showed above β-lactamase genes. It seems that, the reason is the absence of class-1 integron in all of isolates. About 16.7% of strains were identified as multidrug resistant. Fortunately, all of the isolates were sus­ceptible to meropenem and imipenem which are effective against ESBL pro­ducing strains. The absences of class-1 integron decreases the probability of acquired β-lactamase especially MBL. Thus, absolute susceptibility to carba­penems and ciprofloxacin among P. aeruginosa isolates in pediatric hospital has important implications for empirical antimicrobial therapy. It seems that these properties help to decrease mortality of nosocomial infections within children.