Comparison of Virulence Genes in Staphylococcus aureus and Moraxella catarrhalis Isolated from Respiratory Tract Illnesses at the Molecular Level

Abstract

Patients with pharyngeal infections who sought treatment at Babylon General Teaching Hospital, Al-Hilla Hospital, and the Private Clinic of the Supervisor provided a total of two hundred and four (204) samples for analysis. Swabs of Moraxella catarrhalis were collected from people aged 5 to 80, with one set used for culture and the other set used for direct DNA extraction. Ninety-three percent (199) of the samples grew bacteria in culture, while just six percent (14 samples) did not. It was determined that 116/190 (61.10%) of the total isolates are Gram-positive bacteria and 74/190 (38.90%) are Gram-negative bacteria from the 190 (100%) samples. Laboratory diagnosis by biochemical tests, the Vitek-2 system, and molecular detection by specific primers found that Staphylococcus aureus constituted 38 (20%) of the 116 (100%) Gram-positive bacteria, while Moraxella catarrhalis was the most prevalent with a percentage of 44 (23.2%) of the 74 (100%) Gram-negative bacteria. Molecular analysis of S. aureus revealed that 13 strains, or 34%, possess the fnbA pathogenicity gene. Regarding the M. catarrhalis mcaP gene, 44 out of 44 (100%) were positive. The fnbA gene of S. aureus and the mcaP gene of M. catarrhalis, both of which displayed variation, were sequenced by DNA and then recorded in NCBI-gene sequencing as initially described in Iraq. The adhesion genes fnbA and mcaP of gram-positive S. aureus and gram-negative M. catarrhalis were sequenced and analyzed using DNA sequencing technology. The results showed that local S. aureus isolates (NO. 111 and NO. 181) were closely related to a worldwide S. aureus isolation documented by NCBI-BLAST (AM749012.1), while local isolates (NO. 37 and NO. 95) were closely connected to S. aureus strains from other parts of the world (LC073768.1 and LC073762.1).