Pigmentli ve Pigmentsiz Pseudomonas Aeruginosa Suşlarının Virulans Faktörlerinin Fenotipik ve Genotipik Olarak Karşılaştırılması

Abstract

Pseudomonas aeruginosa is an aerobic, motile, non-spore forming, straight or slightly curved, gram-negative bacilli and it can grow at 42 °C. The incidence of P. aeruginosa has been increased in recent years and its virulence factors are various. It has high morbidity and mortality and its rates of antibiotic resistance is increasing constantly. The aim of this study was to compare the differences in the virulence factors of pigmented and non-pigmented P. aeruginosa isolates. Isolates of patients that were identified as P. aeruginosa were included into the study. Identification was done in Hacettepe University Medical Faculty Microbiology Laboratory. Strains of patients (n: 100) were divided into two main groups. In the first group, strains were isolated from cystic fibrosis patients (n: 50). In the second group, the strains which were isolated from various body parts (pus, urine, burn wounds, sputum, and cerebrospinal fluid) included (n: 50). The isolated P. aeruginosa strains from both main groups were divided into two subgroups according to their pigment production (n: 25). Antibiotic susceptibility tests of all strains were performed by disk diffusion method according to CLSI (Clinical and Laboratory Standards Institute) standards. DNase, protease, elastase, haemolysis and motility tests were performed as phenotypic tests. The presence of several virulence-associated genes encoding exotoxins T (exoT), S (exoS), U (exoU) and Y (exoY) and quorum sensing mediators (rhlA and rhlB) were assessed by Real-time PCR method for genotypic identification. The relationship between pigment production, antibiotic resistance and virulence factors were examined. There was no significant difference between pigmented and non-pigmented isolates when elastolytic activity and mucus production were compared. Pigmented isolates produced significantly more (p≤0.05) protease and haemolysis activity. Motility was present in pigmented isolates more frequently than in non-pigmented isolates. DNase activity was significant in pigmented isolates then non-pigmented isolates (p≤0.05). Antibiotic resistance was present more frequently in non-pigmented isolates than pigmented isolates. Pigmented isolates had more frequently and significant more (p≤0.05) virulence-associated genes rhlB, exoS, exoY (p≤0.05). ExoT was present in pigmented isolates more frequently than in non-pigmented isolates. The results of this study suggest that both phenotypic and genotypic virulence factors are associated with the pigment production in P. aeruginosa. Pigment production is easy to determine, which might be a good starting point to identify the virulence status of an isolate.