Risk factors for healthcare-associated extensively drug-resistant Acinetobacter baumannii infections: a case-control study.
The emergence of extensively drug-resistant Acinetobacter baumannii (XDRAB) is a serious threat to hospitalized patients. From 2008 to 2010, surveillance detected 25 hospital-acquired infection (HAI) cases caused by XDRAB at a medical center in Taipei. The site of XDRAB infection was bloodstream (n = 8), urinary tract (n = 12), lower respiratory tract (n = 3), surgical site (n = 1), and cardiovascular (n = 1). The isolates were resistant to all currently available antibiotics except for colistin. The XDRAB isolates are genetically diverse, shown by pulsed-field gel electrophoresis, but 23 of 25 harbored class 1 integron with a 2.3-kb gene cassette. Most of these isolates carry OXA-23 (n = 21) and OXA-51-like carbapenemase genes (n = 25). To identify the risk factors, a case-control study was conducted. The 25 cases were compared with 100 controls randomly selected from hospitalized patients without XDRAB-HAIs, matched by the onset date, ward, and age, at a ratio of 1∶4. Prior use of imipenem, meropenem, piperacillin/tazobactam or fourth-generation cephalosporins (adjusted OR: 3.2, 95% CI: 1.03-10.2, P = 0.04) and >30 days bed-ridden (adjusted OR: 6.0, 95% CI: 1.3-27.6, P = 0.02) were found to be the independent risk factors for XDRAB-HAIs. These findings highlight that, even in the absence of clonal dissemination, XDRAB can emerge under the selective pressure of broad-spectrum antibiotics and causes subsequent HAIs in compromised hosts. An appropriate response to the XDRAB threat therefore should include a component of prudent use of broad-spectrum antibiotics active against gram-negative bacteria.
Infection Control Office, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan.
Ming-Chin
MC
Chan
Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan.
Sheng-Kang
SK
Chiu
Department of Internal Medicine, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei, Taiwan ; Department of Laboratory Medicine, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei, Taiwan.
Po-Ren
PR
Hsueh
Infection Control Office, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan ; Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan.
Ning-Chi
NC
Wang
Department of Pediatrics, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan.
Chih-Chien
CC
Wang
Department of Internal Medicine, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei, Taiwan ; Institute of Epidemiology and Preventive Medicine, College of Public Health, National Taiwan University, Taipei, Taiwan.
Chi-Tai
CT
Fang
D000151:Acinetobacter Infections / Q000188:drug therapy / Q000453:epidemiology* / Q000382:microbiology*; D040981:Acinetobacter baumannii / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology*; D000368:Aged; D000890:Anti-Infective Agents / Q000494:pharmacology / Q000627:therapeutic use; D001426:Bacterial Proteins / Q000235:genetics; D015373:Bacterial Typing Techniques; D016022:Case-Control Studies; D003428:Cross Infection / Q000188:drug therapy / Q000453:epidemiology* / Q000382:microbiology*; D003695:Delivery of Health Care; D024901:Drug Resistance, Multiple, Bacterial / Q000187:drug effects; D016521:Electrophoresis, Gel, Pulsed-Field; D005260:Female; D005798:Genes, Bacterial / Q000235:genetics; D006801:Humans; D032023:Integrons / Q000235:genetics; D008297:Male; D008826:Microbial Sensitivity Tests; D015999:Multivariate Analysis; D012307:Risk Factors; D013624:Taiwan / Q000453:epidemiology; D001618:beta-Lactamases / Q000235:genetics
D000890:Anti-Infective Agents; D001426:Bacterial Proteins; D001618:beta-Lactamases; C063912:carbapenemase