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Volume 42, Number 3, June 2009

Gene cassette arrays, antibiotic susceptibilities, and clinical characteristics of Acinetobacter baumannii bacteremic strains harboring class 1 integrons


Yi-Tzu Lee, Li-Yueh Huang, Te-Li Chen, Leung-Kei Siu, Chang-Phone Fung, Wen-Long Cho, Kwok-Woon Yu, Chen-Yi Liu
Department of Medicine, Chutung Veterans Hospital, Chutung; Division of Infectious Diseases, Department of Medicine, Taipei Veterans General Hospital, Taipei; Division of Clinical Research, National Health Research Institutes, Taipei; School of Medicine, National Yang-Ming University, Taipei; and Department of Pathology and Laboratory Medicine, Taipei Veterans General Hospital, Taipei, Taiwan

Received: January 3, 2008    Revised: May 2, 2008    Accepted: May 23, 2008   

 

Corresponding author:

Dr. Te-Li Chen, Division of Infectious Diseases, Department of Medicine, Taipei Veterans General Hospital, No. 201, Sec. 2, Shih-Pai Road, Taipei, Taiwan. E-mail: Dr. Te-Li Chen This e-mail address is being protected from spam bots, you need JavaScript enabled to view it

 



 

Background and purpose: 

Acinetobacter baumannii isolates containing class 1 integrons belong to different clones, but only a few strains are successful at causing infection. This study was conducted to compare the characteristics among these clones with different epidemicity.
 



 

Methods:

 Eighty eight bacteremic isolates of A. baumannii were collected in a medical center in Taiwan during a 3-year period. The gene cassettes and antibiotic susceptibilities of the bacterial isolates were delineated and the patients’ characteristics were compared.
 



 

Results:

Class 1 integrons were detected in 75 isolates (85.2%). Most of the isolates belonged to 2 major clones, but only 1 of the 2 clones caused outbreaks in several hospitals in Taiwan. Restriction analyses of variable regions of the integron revealed identical gene cassettes among isolates within the same clone. The cassette arrays of the 3 clones were aacA4, catB8, aadA1 (clone I, epidemic clone); dhfr XII, unknown open reading frame (orfF), aadA2 (clone II, endemic clone); and aacC1, 2 unknown open reading frames (orfX, orfX'), aadA1a (clone III). The epidemic and endemic strains were multidrug resistant, but the former presented a higher resistance rate to ampicillin-sulbactam. Infections with epidemic strains were significantly associated with prior use of cephalosporins, but didn’t contribute to a higher mortality rate.

 



 

Conclusion:

Judicious use of cephalosporins and rapid identification using the integron typing method might be helpful for the prevention of further spread of strains with epidemic potential.



 

Key words:

Acinetobacter baumannii; Disease attributes; Disease outbreaks; Drug resistance, microbial; Integron integrase IntI1



 

J Microbiol Immunol Infect. 2009;42:210-219.