Molecular Analysis of lasA, lasB, and toxA Genes in Clinical Isolates of Pseudomonas Aeruginosa by the PCR Technique Ayhan Rashid Mahmood Microbiology Department / College of Medicine / University of Kirkuk/ Iraq E-mail: ayhan39b@uokirkuk.edu.iq Background: Pseudomonas aeruginosa (P. aeruginosa) is a type of opportunistic bacteria, which may infect almost all tissues, immunocompromised people, and cause hospital-acquired illnesses as well. It has a variety of virulence variables that might attribute to its pathogenesis. The toxA (exotoxin A), lasA (protease) and lasB (elastase) genes are among these virulence variants. Methods: In present study, 115 clinical samples were collected from patients. Conventional morphological and biochemical assays were used to identify the isolates of P. aeruginosa. PCR technique was performed for detection of lasA, lasB, and toxA genes in clinical specimens of P. aeruginosa. Results: Of all the samples, P. aeruginosa isolates were identifed in 25 clinical samples and their distribution was as follows: 8 (40%) wounds, 5 (7.14%) urine, 3 (100%) blood, 3 (37.5%) sputum, 2 (28.57%) CSF, 2 (50%) pus, and 2 (66.7%) renal abscess. Results of molecular analysis indicated the presence of virulence genes lasA, lasB, toxA in 14 (56%) of P. aeruginosa isolates while both lasA and lasB genes were detected in 15 (60%) isolates. While 16 (64%) of isolates harbored lasB and toxA genes. All these virulence genes were mostly found in pus, sputum, blood, and wound samples. Keywords: P. aeruginosa, virulence variants, PCR. Original Article Abstract INTRODUCTION Gram-negative bacterium P. aeruginosa results in a wide range of illnesses, including illnesses of the urinary system, bloodstream infections, and pneumonia. This bacterium has inherent mechanism of resistance to various antibacterial drugs such as tetracycline, beta-lactams, trimethoprim/sul- famethoxazole, and chloramphenicol. In addition, through mobile genetic elements, P. aeruginosa may develop other drug resistance mechanisms, which also complicate the treatment of the infections it induces. [1,2] The increase in the prevalence of P. aeruginosa species resistant to such antibacterial drugs has increased the risk of hospitalization, total cost as well as rate of death. [3] Its ability to infect the host is related to its role in regulating virulence genes which respond to external stimuli. [4,5] Pathogenesis of P. aeruginosa is complex and depends on the production of several cell-associated genetic variants, bacterial toxins and enzymes. [6] Exotoxins are either passively or actively released from the cell through various protein secretory mechanisms such as I, II, III, IV, and V. [7,8] P. aeruginosa carries several genes including toxA, lasA, Access this article online Quick Response Code: Website: www.jnsbm.org DOI: https://doi.org/10.4103/jnsbm.JNSBM_14_1_2 and lasB which comprise type II secretory mechanisms. [9] Exotoxin A, which is expressed via toxA gene is a toxin that suppresses protein production. [10] Throughout this mechanism, the nicotinamide adenine dinucleotide (NAD) and adenosine-5’-diphosphate-ribosyl (ADP- ribose) are transmitted to the multicellular organisms’ elongation factor-2 that inhibits the activity of this factor and eventually suppresses protein production. [11] LasA (protease) and lasB (elastase) have potent elastolytic function and are able to repress a broad variety of biological tissues; whilst the lasA has a limited elastolytic action, yet it may increase the expression of the lasB gene. [7] Elastase B, produced via the lasB gene, is a zinc metalloprotease which shows elastolytic action on lung tissue and destroys proteins like collagen and elastin. [12] Moreover, it also degrades proteins of immune system such as cytokines. [13] Address for Correspondence: Microbiology Department / College of Medicine / University of Kirkuk/ Iraq. Email: ayhan39b@uokirkuk.edu.iq Submitted: 15 th December, 2022 Received: 30 th December, 2022 Accepted: 20 th February, 2023 Published: 28 th February, 2023 This is an open access journal, and articles are distributed under the terms of the Creative Commons Attribution-Non Commercial-ShareAlike 4.0 License, which allows others to remix, tweak, and build upon the work non-commercially, as long as appropriate credit is given and the new creations are licensed under the identical terms. How to cite this article: Mahmood A R. Molecular Analysis of lasA, lasB, and toxA Genes in Clinical Isolates of Pseudomonas Aeruginosa by the PCR Technique. J Nat Sc Biol Med 2023;14:10-16 © 2023 Journal of Natural Science, Biology and Medicine 10