Epidemiology and clonality of multidrug-resistant Acinetobacter baumannii from a healthcare region in Hong Kong

• Published in: The Journal of hospital infection 2010-04, Vol.74 (4), p.358-364
• Main Authors: Ho, P.L, Ho, A.Y, Chow, K.H, Lai, E.L, Ching, P, Seto, W.H
• Format: Article
• Language: English
• Subjects: Acinetobacter baumannii; Acinetobacter baumannii - classification; Acinetobacter baumannii - drug effects; Acinetobacter baumannii - isolation & purification; Acinetobacter Infections - epidemiology; Acinetobacter Infections - microbiology; Aged; Aged, 80 and over; Anti-Bacterial Agents - pharmacology; Bacterial Typing Techniques; Biological and medical sciences; Cluster Analysis; Cross Infection - epidemiology; Cross Infection - microbiology; DNA, Bacterial - chemistry; DNA, Bacterial - genetics; Drug Resistance, Multiple, Bacterial; Electrophoresis, Gel, Pulsed-Field; Female; Health Facilities; Hong Kong - epidemiology; Humans; Infectious Disease; Infectious diseases; Male; Medical sciences; Middle Aged; Molecular epidemiology; Molecular Sequence Data; Multilocus sequence typing; Polymorphism, Restriction Fragment Length; Risk Factors; Wound Infection - epidemiology; Wound Infection - microbiology
• ISSN: 0195-6701; 1532-2939
• DOI: 10.1016/j.jhin.2009.10.015

Summary We assessed the risk factors and molecular epidemiology of multidrug-resistant Acinetobacter baumannii (MDR-AB) in Hong Kong. The patients were treated in five hospitals in a healthcare region during 2005–2006. We performed genomic identification by amplified rRNA gene restriction analysis (ARDRA) and investigated the existence of metallo-β-lactamases and the clonality of representative MDR-AB strains by phenotypic and molecular methods. Forty-five subjects with MDR-AB were compared with 135 controls (patients with no MDR-AB). In the logistic regression, chronic wound (odds ratio: 29.5, 95% confidence interval: 8.1–107.2; P < 0.001) was the only factor independently associated with MDR-AB colonisation or infection. ARDRA identified all 45 MDR-AB as genomic species 2TU. Pulsed-field gel electrophoresis clustered all except two isolates into two clonal types, designated HKU1 and HKU2 with 24 and 19 isolates, respectively. The main features of HKU1 strains were ST26, adeB type XII, positivity for blaOxA-23-like and blaOxA-51-like genes and high level resistance to carbapenems. Most HKU1 strains retained susceptibility to gentamicin, cotrimoxazole and minocycline. By contrast, HKU2 strains exhibited ST22, adeB type II, and were usually positive only for the blaOxA-51-like gene and resistant to gentamicin, cotrimoxazole and minocycline. Both clones were found to have disseminated widely. In conclusion, clonal expansion is playing major roles in the increase of MDR-AB in these hospitals in Hong Kong. The findings highlight the need to enhance infection control measures.