Molecular epidemiology of Acinetobacter baumannii in Iran: endemic and epidemic spread of multiresistant isolates.

OBJECTIVES We examined the molecular epidemiology of Acinetobacter baumannii clinical isolates from two cities (Tehran and Tabriz) of Iran. METHODS DiversiLab repetitive extragenic palindromic PCR (rep-PCR), multilocus sequence typing and sequence group multiplex PCR were performed. The presence of resistance mechanisms including metallo-β-lactamases, extended-spectrum β-lactamases, OXA carbapenemases, aminoglycoside-modifying enzymes and RNA methylases was also investigated. RESULTS DiversiLab rep-PCR identified 11 clusters and 11 singleton isolates. Twelve sequence types (STs), including six novel types, were identified. Sequence groups (SGs) 1-3 as well as five additional banding patterns were detected by multiplex PCR. A local outbreak in a general hospital in Tabriz with an SG1/ST2 profile was identified. Isolates of international clone II showed the highest prevalence and the most heterogeneous combination of resistance determinants. CONCLUSIONS Several different multiresistant strains of A. baumannii were shown to circulate in Iran. The selection and spread of the SG1/ST2 clone might have been favoured by the acquisition of resistance genes in the absence of adequate infection control measures.