Microbiological Study on Nosocomial Acinetobacter baumannii Infection with Molecular Characterization of Metallo Beta- Lactamases

Abstract

Acinetobacter baumannii is a nosocomial pathogen which the World Health OrganizationI• s considered number one critical priority pathogen. It has become a growing problem in hospitals as a predominant multi-drug resistant that left clinicians with limited treatment options. Its main mechanisms for β-lactam resistance are the production of carbapenems especially Amber class D β-lactamases followed by B β-lactamases. NDM-1 which is an example of the later poses a major health concern particularly in the light of its spread through population. To precede our study, 74 Acinetobacter baumannii isolates were collected from hospital laboratories during the period from July 2017 till June 2018. Antimicrobial susceptibility testing was done by Kirby-Bauer Disc Diffusion method (KBDD) and Minimum Inhibitory Concentration (MIC) was detected using E-test method. CRAB ones were tested by both of Modified Hodge Test (MHT) and Imipenem EDTA Combined Disc Test (CDT) to detect metallo βeta-lactams (MBL) producers. Then existence of NDM-1 gene was further identified. All of the 74 Acinetobacter baumannii isolates were found to be multi-drug resistant (MDR). 36 of them (48.65%) were resulted as carbapenem resistant and 27 (36.49%) were metallo βeta-lactams (MBL) producers. 12/27 (44.44%) MBL poses NDM-1 gene in the first detection procedure while the other negative 15 ones the percentage of NDM-1 was found to be 10/15 (66.67%) when using different primer. PCR products were then verified by DNA sequencing. The final consensus sequences were analyzed and submitted to NCBI GenBank data base, representing accession numbers are JF838352.1, MK682768.1 and MN251667.1. The alignments showed similarity ranged from 94%-96.4% amino acids identity. We concluded that detection of antibiotic resistant Acinetobacter baumannii revealed that multi-drug resistance arises dramatically due to the indiscriminate use of antibiotics and the poor applying of infection control precautions. These results emphasize the importance of implementation and comply both of antibiotic and infection control policies.