Identification of Acinetobacter baumannii and detection of ß – lactam antibiotic resistance genes in clinical samples by multiplex PCR

Phan-Canh Trinh, Thao Le-Thi-Thanh, Thuy Ngo-Thi-Bich, Thanh Nguyen-Thi-Thanh, Linh Ho-Le-Truc, Tu-Anh Nguyen 2020. biorxiv 2020.


Acinetobacter baumannii is the leading cause of hospital-acquired infection in Vietnam. Of note, antibiotic resistance genes are significantly popular in clinical isolates of A. baumannii. Therefore, rapid identification of A. baumannii and determination of antibiotic resistance genes will help to make effective clinical decisions related to antibiotic use. This paper proposes a multiplex PCR to identify Acinetobacter baumannii and detect their ß-lactam antibiotic resistance genes in clinical isolates. Multiplex PCR was applied to amplified recA gene and region ITS 16S - 23S rDNA for Rapid detection of A. baumannii. The two antibiotic resistance genes - blaOXA-51-like, ampC gene - were detected by multiplex PCR and three genes coding Extended-spectrum beta-lactamases - blaCTX-M, blaTEM, blaSHV genes - were subjected to PCR. 49 bacteria strains were subjected to colony PCR. The result showed that 46 strains were A. baumannii and 3 strains belonged to the genus Acinetobacter. The multiplex PCR showed that all of 46 A. baumannii containing the blaOXA-51-like gene and the AmpC gene; 34 strains possess the gene blaTEM and none of them has blaCTX-M and blaSHV genes. The results of the multiplex PCR are the same as those of the in vitro antibiotic sensitivity testing of A. baumannii. However, applying the multiplex PCR directly from the bacteria colony, we can proceed simultaneously with the bacterial identification and the antibiotic resistance gene detection.

  • 100% of isolates of A. baumannii contains the blaOXA-51-like gene and the AmpC gene.

  • 34/46 isolates possess the gene blaTEM, however, do not contain blaCTX-M and blaSHV genes.

  • Combined disc test with cefotaxime/clavulanic acid/boronic acid is an excellent method to analyse ESBL phenotype.