Iraqi Postgraduate Medical Journal

Abstract

ABSTRACT:
BACKGROUND:
P. aeruginosa remains an important cause of life-threatening bloodstream infection in
immunocompromised patients, particularly those with hematologic malignancies complicated by
neutropenia. One of the most worrisome characteristics of P. aeruginosa consists is its low
antibiotic susceptibility This low susceptibility is attributable to concerted action of
chromosomally-encoded multidrug efflux pumps genes. These genes are often controlled by
regulatory gene located on the same operon of efflux pump. One of particular significance is the
MexAB - OprM efflux system, which is expressed constitutively, thereby contributing to the
well-known intrinsic resistance of this organism to multiple antimicrobials.
OBJECTIVE:
To detect the occurrence of mexAB-OprM operom on the chromosomes of septicemic P.
aeruginosa(SPA).
METHODS:
This study was include 53 Pseudomonas aeruginosa isolates isolated from patients their ages ranging
from two days to 73 years,28 males and 25 females. Some of the isolates were isolated from acute,
15(28.3%), and chronic, 7 (13.2%), leukemic patients, 5 (9.4%) from each lymphoma and
gastrointestinal neoplasms patients. Nine (17%), 3(5.7%), 6 (11.3%) and 3(5.7%) from urogenital
neoplasms, breast cancer patients, septicemic patients due to burn infections and neonatal
septicemia respectively. Chromosomal DNA was extracted from SPA isolates and subjected to PCR to
amplify three genes of mexAB-OprM efflux pump.
RESULTS:
Multiplex PCR of mexAB-OprM efflux pump genes revealed that 53 (100%) were positive to all three
genes of operon, mexA, mexB and the regulatory gene, mexR.
CONCLUSION:
P. aeruginosa can cause septicemia in cancer patients and other compromised patients, like patients
suffering from extensive burns and neonatal infants. mexAB-OprM efflux pump genes are a
chromosomal encoded genes and can be used as a markers in identification of SPA by molecular
methods. These genes can be used individually or collectively in rapid identification of SPA, and rapid
detection for mexAB-OprM efflux pump occurrence on their chromosomes.