Effect of antibiotics on the expression of pyocyanin synthetic genes in Pseudomonas aeruginosa isolated from different clinical sources of a few hospitals in Mosul, Iraq

Abstract

Pyocyanin is a blue-green phenazine pigment and one of the most virulent factors produced by the opportunistic pathogen Pseudomonas aeruginosa. It has a redox activity and a toxic impact on living cells, as it interacts with oxygen to produce reactive oxygen species (ROS). Using antibiotics at a sub-lethal dose has an unexpected influence on the expression of pyocyanin-producing genes. In this study, qPCR technique was performed to identify the effect of eight antibiotics (cefotaxime, ampicillin, amoxiclav, ceftazidime, ceftriaxone, chloramphenicol, kanamycin and tetracycline) on the gene expression level of pyocyanin synthetic genes in P. aeruginosa isolated from different clinical sources of a few hospitals in Mosul, Iraq using qPCR technique. It was found that when P. aeruginosa was grown in media containing cefotaxime (CTX 30 µg/mL), ampicillin (AM 25 µg/mL) or amoxiclav (AMC 30 µg/mL), up-regulated the expression of pyocyanin producing genes belonging to different operons thereby increased pyocyanin production. Overexpression occurred in (CTX) treatment in PhzA1 operon with 235.56 fold change and phzM and phzS genes with 340.14, 280.13 fold change, respectively. Lower expression levels showed in tetracycline (TE 30 µg/mL) treatment, which was a (1.44) fold change for phzA1 and a (1.64, 1.08) fold change for phzM and phzS genes. More caution should be considered when delivering antibiotics to treat P. aeruginosa infections, as using drugs that the bacteria resists or at sub-lethal concentrations may trigger up-regulation of virulence factors, aiding in the spread of the disease.