Molecular investigation of type III secretion system toxins-encoding genes in clinical isolates of Pseudomonas aeruginosa

Abstract EN

Objectives : This study is aimed to isolate P.

aeruginosa from different clinical cases and to detect the prevalence of virulence genes encoding type III secretion system toxins in these clinical isolates. Materials and methods : In this study a total of 422 clinical samples including burn, wound, ear, urine ,abscess and stool were aseptically taken from out- and inpatients who admitted into two hospitals in Hilla City (Teaching Al-Hilla Hospital and Babylon Hospital for Maternity and children during a period of three months (from March 2011 to June 2011).

All samples were subjected to bacterial cultivation for the isolation of P.

aeruginosa.

The isolated P.

aeruginosa was diagnosed depended on morphological, biochemical and molecular standard characteristics.

Type III secretion toxins-encoding genes (exoS, exoY, exoT and exoU) were detected by PCR and the amplification products were separated in 1 % agarose gels containing ethidium bromide. Results : Out of 422 samples, P.

aeruginosa was isolated from 54 samples(12.8 %).

The distribution of these isolates were : 22 (55 %) from burn samples, 2 ; (50 %) from diabitics foot samples, 8 (14.8 %) from wound samples, 8 (32 %) from ear samples, 3 (11 %) from abscess samples, 7 (4 %) from stool samples, 4 (4 %) from urine samples and 0 sputum samples.

The genotypic properties of type III secretion system toxins was detected by polymerase chain reaction (PCR).

The results of this study revealed that exoS gene found in 10 / 20(50 %) of isolates, exoY gene accounted for 12 / 20 (60 %) of isolates, while exoT detected in most isolates17 / 20 (85 %) and exoU was detected in minaroty of isolates 5 / 20 (25 %). Conclusion : Type III secretion system toxins-encoding genes found in isolated P.aeruginosa, in which exoT, exoY and exoS gene detected in most isolates while exoU gene was detected in minaroty of the isolates.