Emergence in Taiwan of novel imipenem-resistant Acinetobacter baumannii ST455 causing bloodstream infection in critical patients.

Abstract

BACKGROUND:

Acinetobacter baumannii is one of the most important nosocomial pathogens worldwide. This study aimed to use multilocus sequence typing (MLST) for the epidemiological surveillance of A. baumannii isolates in Taiwan and analyze the clinical presentations and patients' outcome.

METHODS:

MLST according to both Bartual's PubMLST and Pasteur's MLST schemes was applied to characterize bloodstream imipenem-resistant A. baumannii (IRAB) infection in intensive care units in a medical center. A total of 39 clinical IRAB bloodstream isolates in 2010 were enrolled. We also collected 13 imipenem-susceptible A. baumannii (ISAB) bloodstream isolates and 30 clinical sputum isolates (24 IRAB and 6 ISAB) for comparison. Clinical presentations and outcome of the patients were analyzed.

RESULTS:

We found that infection by ST455(B)/ST2(P) and inappropriate initial therapy were statistically significant risk factors for mortality. More than one-third of the IRAB isolates belonged to ST455(B)/ST2(P). Most ST455(B)/ST2(P) (80%) carried ISAba1-blaOXA-23, including 10 (66.7%) with Tn2006 (ISAba1-blaOXA-23-ISAba1) in an AbaR4-type resistance island. ST455(B)/ST2(P) appears to evolve from ST208(B)/ST2(P) of clonal complex (CC) 92(B)/CC2(P). In this hospital-based study, A. baumannii ST455 accounted for 38.5% of IRAB bacteremia, with a high mortality of 86.7%. Approximately 85% of ST455(B)/ST2(P)bacteremia had a primary source of ventilation-associated pneumonia.

CONCLUSION:

We report the emergence in Taiwan of IRAB ST455(B)/ST2(P), which is the current predominant clone of IRAB in our hospital and has been causing bacteremia with high mortality in critical patients.

• Authors: Hao-Yuan Lee, Chih-Wei Huang, Chyi-Liang Chen, Yi-Hsin Wang, Chee-Jen Chang, Cheng-Hsun Chiu
• Journal: Journal of microbiology, immunology, and infection = Wei mian yu gan ran za zhi (J Microbiol Immunol Infect) Vol. 48 Issue 6 Pg. 588-96 (Dec 2015) ISSN: 1995-9133 [Electronic] England
• PMID: 26055692 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: Copyright © 2015. Published by Elsevier B.V.

Chemical References

• Anti-Bacterial Agents
• DNA, Intergenic
• Imipenem

Topics

• Acinetobacter Infections (drug therapy, epidemiology, pathology)
• Acinetobacter baumannii (drug effects, genetics, isolation & purification)
• Aged
• Anti-Bacterial Agents (therapeutic use)
• Bacteremia (drug therapy, epidemiology, microbiology)
• Cross Infection (microbiology)
• DNA, Intergenic (genetics)
• Drug Resistance, Bacterial (genetics)
• Female
• Humans
• Imipenem (therapeutic use)
• Intensive Care Units
• Male
• Microbial Sensitivity Tests
• Middle Aged
• Multilocus Sequence Typing
• Taiwan (epidemiology)