| Description: |
Acinetobacter baumannii (strain ACICU) is an important opportunistic pathogen worldwide responsible for large outbreaks of nosocomial infection which account for 2-10% of all Gram-negative infections. A. baumannii infections include nosocomial pneumonia, secondary meningitis, skin, soft tissue and urinary tract infections and bacteremia, and result in high (up to 50%) morbidity and mortality. A. baumannii has simple growth requirements, exploiting a variety of nutritional sources, and is adaptable to a range of temperature, pH, salinity and humidity.
Infections by this organism are becoming increasingly problematic due to the high number of resistance genes found in clinical isolates. Multidrug resistant clones of A. baumannii are emerging and spreading throughout many geographic areas. The emergence of two pan-European epidemic clones, referred to as European clones I and II, has been reported in north-western Europe since the1980s, and has been then documented in many European regions. These epidemic lineages are endowed with a broad range of antibiotic resistance, although individual strains can display different types and combinations of resistance determinants. Treatment options for multidrug resistant A. baumannii infections are generally limited to carbapenems, but the emergence of imipenem and meropenem resistance is a growing source of concern.
Acinetobacter baumannii strain (strain ACICU) belongs to the European clone II and carries the plasmid-mediated blaOXA58 carbapenem resistance gene. An antibiotic resistance island, AbaR2, is present in ACICU, plausibly evolving by reductive evolution from the AbaR1 island previously described in the multiresistant A. baumannii AYE strain. Moreover, 36 putative alien islands (pAICUs) were detected in the ACICU genome, 24 of which had previously been described in the ATCC17978 genome, 4 here proposed for the first time and present in both ATCC17978 and ACICU, and 8 unique to the ACICU genome. Fifteen pAICUs encode genes related to drug resistance, including membrane transporters and ex novo acquired resistance genes. These findings provide novel insight into the genetic basis of A. baumannii. Most of these genes appear to have been transferred horizontally from other organisms. |
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