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Volume 39, Number 5, October 2006

Predictive biomarkers for drug-resistant Acinetobacter baumannii isolates with blaTEM-1, AmpC-type bla and integrase 1 genotypes


Chang-Hua Chen, Tzuu-Guang Young, Chieh-Chen Huang
Division of Infectious Diseases, Department of Internal Medicine and Infection Control Committee, Changhua Christian Hospital, Changhua; College of Life Science, National Chung Hsing University, Taichung; and Taipei City Hospital, Ren-ai Branch, Taipei, Taiwan

Received: August 23, 2005    Revised: February 16, 2006    Accepted: February 21, 2006   

 

Corresponding author:

Dr. Chieh-Chen Huang, College of Life Science, National Chung Hsing University, Taichung, Taiwan. E-mail: cchuang@dragon.nchu.edu.tw This e-mail address is being protected from spam bots, you need JavaScript enabled to view it

 



 

Background and purpose: 

We tested whether antibiotic susceptibilities of drug-resistant Acinetobacter baumannii isolates could be used to predict the clinically important genotypes blaTEM-1, AmpC-type bla, and integrase 1 gene (IntI1).

 



 

Methods:

We analyzed 401 A. baumannii isolates obtained at Changhua Christian Hospital between April 2001 and March 2002. The isolates were all from blood cultures, and identification of A. baumannii was confirmed by API-20NE. Antibiotic susceptibility testing (phenotype) was performed by disk diffusion method. Polymerase chain reaction was used to detect the genes blaTEM-1, AmpC-type bla and IntI1.

 



 

Results:

Of 32 A. baumannii isolates, 10 possessed blaTEM-1, 21 AmpC-type bla, and 26 IntI1. Resistance to ceftazidime (CAZ) predicted blaTEM-1 genotype with 63.6% sensitivity, 100% specificity, 55.6% positive predictive value (PPV) and 0% negative predictive value (NPV). Trimethoprim-sulfamethoxazole (SXT) and gentamicin (GM) resistance predicted IntI1 genotype with 83.3% sensitivity, 71.4% specificity, 95.2% PPV and 45.4% NPV. No resistance phenotype could predict the AmpC-type bla genotype.

 



 

Conclusion:

CAZ resistance predicted the blaTEM-1 genotype with 100% specificity, and SXT and GM resistance predicted the IntI1 genotype with 92.5% PPV. Therefore, antibiotic susceptibilities to CAZ, SXT, and GM can be utilized clinically to detect critical genotypes in A. baumannii.

 



 

Key words:

Acinetobacter baumannii, bacterial drug resistance, beta-lactamases genetics, biological markers, genotype


 



 

J Microbiol Immunol Infect 2006;39:372-379.