Study on the molecular mechanism of aminoglycoside resistance to Acinetobacter baumannii

Abstract

Abstract: Objective　To investigate the molecular epidemiology and mechanism of aminoglycoside resistance to Acinetobacter baumannii isolates. Methods　Agar-dilution was carried out to detect the minimum inhibitory concentration（MIC）, and enterobacterial repetitive intergenic consensus（ERIC）-polymerase chain reaction（PCR） was performed to analyze the molecular epidemiology of aminoglycoside-resistance isolates. Specific PCR，DNA sequencing，conjugation experiments were carried to confirm the transmission mechanism. Results　All the clinical isolates were resistant to most drugs including aminoglycosides, and ERIC-PCR showed the isolates belonged to 7 genotypes. Specific PCR and DNA sequencing revealed that all isolates encoded aminoglycoside-modifying enzyme genes, efflux pump gene and methylase gene. Conclusions　Producing of aminoglycoside-modifying enzyme and methylase mainly contribute to reduce the susceptibility of aminoglycosides in Acinetobacter baumannii. Efflux pump overexpression may as a cofactor in high-level aminoglycoside resistance. Vertical transmission and plasmid-mediated horizontal transmission are probably the principal epidemical mechanisms.

Key words: Tryptophan, Kynurenine, Kynurenic acid, Indoleamine 2;3-dioxygenase, Kynurenine aminotransferase, Essential hypertension

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