Toxigenecity and Virulence variations of Pseudomonas aeruginosa from out-patients hospitals in Southwest Nigeria

Background Multidrug resistant (MDR) Pseudomonas aeruginosa isolates harboring genes for virulence and antibiotic resistance, have grown more prevalent lately. These strains pose a major threat to the general population, especially in tertiary care settings. There is a paucity of information on toxigenic and virulence diversity of multidrug resistant P. aeruginosa in Nigeria, hence, the need to characterize and determine the variations of the virulence genes. Methods Six hundred clinical samples from different anatomical sites were collected aseptically from Lagos University Teaching Hospital (LUTH), University of Medical Sciences, Ondo (UNIMED) and Federal Medical Centre, Abeokuta (FMC). Pseudomonas aeruginosa was isolated using cetrimide agar identified using biochemical tests. Antibiotic sensitivity was done by disc diffusion method. Protease, phospholipase C (lecithinase), caseinase and gelatinase presence were assayed for. Genomic DNA was extracted from P. aeruginosa isolates and screened for the presence of N-Acetylneuraminate synthase (NaN), Elastase B ( Las B), Exotoxin A (ExoA), Exoenzyme S (ExoS) and Exoenzyme U (ExoU) virulence genes by PCR. Results Three hundred and sixty bacterial isolates identified from clinical samples are as follows: Pseudomonas aeruginosa (11.3%), Escherichia coli (18.0%), Klebsiella pneumoniae (14.3%), Staphylococcus aureus (10.2%), Proteus mirabilis (3.2%), Streptococcus pnuemoniae (2.3% ), Enterobacter aerogenes (0.5%) and Acinetobacter baumanni (0.1%). Enzymes detected in the P. aeruginosa isolates were Phospholipase C (77.9%), caseinase (83.9%), gelatinase (98.5%) and protease (88.2%). The P. aeruginosa isolates were all resistant to ampicillin and cloxacillin; 26 (38.2 %) strains exhibited multidrug resistance. Virulence Las B elastase gene was detected in all 14 multi resistant P. aeruginosa , ExoA was detected in 5, ExoS in 4, ExoU in 5 and NaN in 4 isolates: Four (28.6%) Conclusion The study confirmed presence and variations of toxic genes in Pseudomonas aeruginosa isolated from all the three tertiary hospitals.