Control of an outbreak of Acinetobacter baumannii infections using vaporized hydrogen peroxide A. Chmielarczyk a, * , P.G. Higgins b , J. Wojkowska-Mach a , E. Synowiec c , E. Zander b , D. Romaniszyn a , T. Gosiewski a , H. Seifert b , P. Heczko a , M. Bulanda a a Jagiellonian University Medical College, Krakow, Poland b Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, Cologne, Germany c John Paul II Regional Teaching Hospital, Krakow, Poland A RT IC L E I N F O Article history: Received 25 February 2012 Accepted 17 May 2012 Available online 22 June 2012 Keywords: Hospital-acquired infection Multidrug-resistant Acinetobacter baumannii Outbreak Vaporized hydrogen peroxide S U M M A RY Background: Multidrug-resistant Acinetobacter baumannii (MRAB) is a serious nosocomial pathogen characterized by its survival on inanimate surfaces for long periods, making control of outbreaks difficult. Aim: To analyse two hospital outbreaks caused by MRAB, determine their epidemiology, carbapenem-resistance mechanisms and assess the effectiveness of surface disinfection by vaporized hydrogen peroxide (VHP). Methods: MRAB strains were isolated from patients in two intensive care units (ICUs). Antimicrobial susceptibility testing was performed by E-test. Polymerase chain reaction (PCR) was used to detect the presence of the most common A. baumannii carbapenemases. Epidemiological typing was performed by rep-PCR (DiversiLab) and pulsed-field gel elec- trophoresis. VHP was used to decontaminate the affected ICUs. Findings: MRAB was isolated from 28 patients between January 2009 and September 2010. All isolates were resistant to ciprofloxacin and gentamicin. Twenty-one were also resistant to carbapenems. Carbapenem resistance was associated primarily with the acquired OXA- 23-like enzyme. Genotyping revealed three clones; the predominant clone corresponded to the international clone (IC) 2. Typing of the isolates pointed to a multifocal outbreak without a single source of infection, with horizontal spread of the dominating clone among ICU patients. A combination of rigorous infection control measures including strict isola- tion, education of staff, hand hygiene and surface decontamination using VHP halted the outbreak. Conclusion: The results of this study confirm the importance of rigorous infection prevention and control measures, combined with VHP decontamination in controlling an outbreak of MRAB. Ó 2012 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved. Introduction The genus Acinetobacter are aerobic, non-fermenting Gram-negative rods, some of which are widespread in the natural environment. Acinetobacter baumannii is clinically the * Corresponding author. Address: Jagiellonian University Medical College, 18 Czysta Street, 31-121 Krakow, Poland. Tel.: þ48 12 633 25 67; fax: þ48 12 423 39 24. E-mail address: achmiel@cm-uj.krakow.pl (A. Chmielarczyk). Available online at www.sciencedirect.com Journal of Hospital Infection journal homepage: www.elsevierhealth.com/journals/jhin 0195-6701/$ e see front matter Ó 2012 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.jhin.2012.05.010 Journal of Hospital Infection 81 (2012) 239e245