Molecular detection of the virulence genes of pseudomonas aeruginosa causing an outbreak in a tertiary centre, Selangor.

Pseudomonas aeruginosa is an opportunistic pathogen which is commonly associated with healthcare associated infection (HAI) and outbreaks. They have the ability to possess multiple pathogenic factors which play an important role in causing invasive infections such as surgical site infection (SSI), osteomyelitis, pneumonia, and blood stream infection. Between 2016 to 2017, there were two outbreaks caused by sensitive strain P. aeruginosa in a Tertiary Centre among 17 patients which resulted in multiple complications and fatalities. The outbreak investigation conducted using pulsed field gel electrophoresis (PFGE) revealed seven clonally related P. aeruginosa strains from A to G. The objective of this study is to determine the virulence factors acquired by P. aeruginosa isolates obtained from the clinical samples during the outbreak and to describe the clinical outcome associated with these infections. The P. aeruginosa isolates from outbreak investigation were retrieved from the laboratory’s stock culture collection and revived to determine their virulence genes by polymerase chain reaction (PCR). Six virulence genes were investigated, namely ToxA, ExoS, LasI, LasB, OprI, and OprL genes which encodes for exotoxin A, exoenzyme S, quorum sensing system, alginate, and the last two genes are for peptidoglycan related outer membrane respectively. A total of ten out of 17 clinical isolates, were able to revive. They were represented by clone A, B, C, D, F and G. Results showed that ToxA gene were detected in six isolates only which belonged to clone A (one isolate) and clone C (five isolates). While ExoS, LasI, LasB, OprI, and OprL were detected in all six clones. The P. aeruginosa isolate which belonged to clone A caused pneumonia while P. aeruginosa which belonged to clone C caused surgical site infections which also resulted in complication such as disseminated infections and death. The preservation and the presence of multiple virulence genes among these P. aeruginosa isolates were possible contributing factors to the invasiveness, persistence, and severity of the infection despite the organism being sensitive to the antimicrobials tested. Further investigations of P. aeruginosa virulence genes involving a larger number of isolates and involving different types of infection may reveal more variable virulence genes pattern and would provide a better correlation with their clinical outcomes.