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


RESULTS
Of 32 A. baumannii isolates, 10 possessed bla(TEM-1), 21 AmpC-type bla, and 26 IntI1. Resistance to ceftazidime (CAZ) predicted bla(TEM-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.


CONCLUSIONS
CAZ resistance predicted the bla(TEM-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.
Chen
Chang-Hua
CH
Division of Infectious Diseases, Department of Internal Medicine, Changhua Christian Hospital, Changhua, Taiwan.
Young
Tzuu-Guang
TG
Huang
Chieh-Chen
CC
D000151:Acinetobacter Infections / Q000382:microbiology*; D040981:Acinetobacter baumannii / Q000187:drug effects* / Q000235:genetics; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D000890:Anti-Infective Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics; D015415:Biomarkers; D002442:Ceftazidime / Q000494:pharmacology; D003430:Cross-Sectional Studies; D024901:Drug Resistance, Multiple, Bacterial; D005798:Genes, Bacterial; D005839:Gentamicins / Q000494:pharmacology; D006801:Humans; D019426:Integrases / Q000235:genetics; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D011446:Prospective Studies; D013045:Species Specificity; D013624:Taiwan; D015662:Trimethoprim, Sulfamethoxazole Drug Combination / Q000494:pharmacology; D001618:beta-Lactamases / Q000235:genetics
D000900:Anti-Bacterial Agents; D000890:Anti-Infective Agents; D001426:Bacterial Proteins; D015415:Biomarkers; D005839:Gentamicins; D015662:Trimethoprim, Sulfamethoxazole Drug Combination; D002442:Ceftazidime; D019426:Integrases; C048795:AmpC beta-lactamases; D001618:beta-Lactamases; C034413:beta-lactamase TEM-1