A multidrug-resistant Acinetobacter baumannii outbreak in intensive care unit: antimicrobial and organizational strategies.

Purpose: Multidrug-resistant Acinetobacter baumannii (MRAB) is an emerging cause of intensive care unit (ICU) outbreaks. Patients are the main reservoirs, inducing cross transmission. We describe an MRAB outbreak that occurred in the Prato Hospital ICU in June to August 2009.

Materials And Methods: The ICU consists of 2 separated 4-bed rooms (rooms A and B). The MRAB-positive patients were included in our study. During the outbreak, infection control measures were enhanced; patients and environmental screenings were performed. A 6-month follow-up was carried out.

Results: Four of 26 patients admitted during the outbreak were MRAB positive. All patients were located in room A; no case was detected in room B either in the hospital or during the follow-up. Management included closure to new admissions, reinforcement of infection control measures, patient and environmental screenings, discharge of room B MRAB-negative patients for at least 5 days after the first case identification. All isolates were carbapenems resistant and tigecycline and colistin susceptible. All patients received tigecycline: 2 were successfully treated, 1 died because of preexisting illness, and 1 developed resistance and recovered after colistin therapy.

Conclusions: Enhanced infection control measures and adequate antibiotic strategy limited the outbreak. Tigecycline allowed rapid recovery. Nevertheless, resistance ensued; so colistin remained the only therapeutic option. However, pan-drug resistance has been reported.