Nosocomial Outbreak of Extensively and Pan Drug-Resistant Acinetobacter baumannii in Tertiary Hospital in Central Part of Iran

Background: Acinetobacter baumannii has emerged as a cause of nosocomial infections in hospitalized patients, particularly in intensive care units. Carbapenems are a common choice for treating nosocomial infections caused by A. baumannii strains. Increasing antimicrobial resistance among Acinetobacter isolates has been documented and multidrug-resistant A. baumannii is recognized to be among the most difficult antimicrobial-resistant bacilli to control and treat. Objectives: This study describes carbapenem resistance in A. baumannii isolates obtained during an outbreak from intensive care units of a peripheral hospital in central part of Iran. Patients and Methods: Sixty-three non-repetitive A. baumannii isolates were collected over a six months period. Susceptibility of the isolated bacteria to a panel of 23 different antimicrobial agents was defined by using the standard disk diffusion method. Production of Metallo-beta-lactamases (MBL) and AmpC beta-lactamase were determined by using the E-test MBL strip and AmpC disk tests, respectively. Results: The present study indicates that carbapenems and new cephalosporin antibiotics were practically ineffective against the extensive drug resistance (XDR) strains. Colistin was observed to be more effective, although in seven cases resistance to colistin observed. AmpC beta-lactamase and MBL could be an important contributory factor for imipenem resistance among the isolates in our hospital. The elevated prevalence of XDR and pan drug resistance (PDR) strains indicates that local antibioti Conclusions: The elevated prevalence of XDR and PDR strains indicates that local antibiotic prescription policies should be revised and infection control should be improved.