engleski

CLONAL SPREAD OF AN IMPORTED STRAIN OF CARBAPENEM RESISTANT ACINETOBACTER BAUMANNII CARRYING GENES FOR OXA-90, OXA-72 AND A TRUNCATED VIM METALLO-β-LACTAMASE GENE TO SPLIT UNIVERSITY HOSPITAL, CROATIA

Acinetobacter baumannii is a well-recognised opportunistic pathogen that gives rise to nosocomial infections and outbreaks, particularly in the intensive care unit setting. The first carbapenem-resistant strain (meropenem MIC 16 μg/ml) at Split University Hospital, Croatia, was isolated in 2002. Between 2002 and 2008, more than 100 clonally-related isolates belonging to the sequence group 2 (European/worldwide clone 1) lineage were collected, with a high percentage of these isolates carrying a blaOXA-107 gene associated with ISAba1. Thus, isolates belonging to the European/worldwide clone 1 lineage and carrying a blaOXA-107 gene can be considered to be the domestic endemic clone. On January 5, 2009, a 51 year-old female was transferred from the General Hospital, Mostar, Bosnia and Herzegovina, to the Intensive Care Unit of Split University Hospital following brain surgery for glioblastoma. According to the transfer letter, multiresistant Acinetobacter spp. was isolated from a bronchial aspirate during hospitalisation in Mostar. The susceptibility pattern of the isolate at this stage showed susceptibility only to colistin and ampicillin/sulbactam. During the next 6 months (January – July 2009), 32 similar consecutive isolates were collected from different patients hospitalised in two ICUs and three different departments at Split University Hospital. All isolates displayed the same resistance pattern, with no inhibition zone around imipenem and meropenem disks, and were collected from blood cultures, urine samples, catheter tip specimens, cerebrospinal fluid, throat and nasal swabs, and bronchial secretions. Pulsed-field gel electrophoresis performed following macrorestriction with ApaI confirmed that all isolates belonged to a single new clone, shown by multiplex PCR to belong to the sequence group 1 lineage (European/worldwide clone 2). Multiplex PCR also revealed that isolates belonging to the new clone possessed blaOXA-51-like and blaOXA-40-like genes. No other class D oxacillinase genes were detected by PCR. Sequencing of the blaOXA-51-like gene (both strands) revealed the presence of a gene encoding OXA-90 (a variant of OXA-66). Sequencing of the blaOXA-40-like gene revealed the presence of a gene encoding OXA-72. PCRs to detect the presence of integrons and MBL genes revealed three different integron structures (530, 750 and 1130 bp, respectively) with the 750 bp and 1130 bp structures containing a truncated (at the 5'- end) VIM-type gene cassette in the distal position. The new clone of A. baumannii belonging to the European/worldwide clone 2 lineage has become dominant in Split University Hospital hospital during the last year and is a major causative agent of nosocomial infection. These findings highlight the importance of international transfer of patients in the spread of novel antimicrobial-resistant pathogens, and emphasise the need for hospitals to isolate and screen patients admitted to hospitals from foreign countries.

Acinetobacter baumannii; carbapenem resistant; OXA-72; VIM metallo-lactamase

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