Multi-resistant Acinetobacter baumannii: description of an outbreak centred on an intensive care unit in an Australian hospital

Abstract

Multi-resistant Acinetobacter baumannii (MRAB) is an increasingly important cause of nosocomial outbreaks, particularly in intensive care units (ICUs). Over a 4-year period, more than 130 patients colonised or infected with MRAB were identified at our institution, with 90 per cent of cases from the adult ICU or neighbouring high-dependency wards. Most isolates were from wound or respiratory sites but 14.5 per cent came from sterile sites. Typing of isolates by pulsed-field gel electrophoresis (PFGE) showed that six distinct pulsotypes circulated during this period, including two strains that exhibited high-level carbapenem resistance. PFGE typing also helped direct infection control efforts, which included isolation/cohorting of cases, emphasis on handwashing and use of barrier precautions by staff, plus improved cleaning of the environment. Inappropriate prescribing of antibiotics, particularly third-generation cephalosporins and carbapenems, was reduced. Despite these measures, control of the outbreak was difficult. MRAB may become endemic in institutions, despite the use of recommended infection control measures.