ABSTRACT
Purpose: the aim of the present study was to determine the role of some virulence determinants and biofilm production in bacteraemia of urinary tract origin by phenotypic defection of these virulence factors. In addition, this research was done to characterize and compare, using genetic techniques, bacterial genes that encode virulence determinants
Methods: a total of 111 strains of Enterobacteriaceae isolated from urine of patients with clinically diagnosed urinary tract infection in Urology and Nephrology Center, Mansoura University, were included in this study. The isolated strains were phenotypically screened for virulence factors, namely mannose-resistant, mannose-sensitive haemagglutination [MRHA, MSHA], hemolysin production, biofilm formation, serum resistance, and lipase, protease and lecithinase production. They were also genotypically examined by PCR for the presence of genes for the virulence factors MRHA [papC], MSHA [fimH], serum resistance [iss] and biofilm,formation [biofilm]
Results: among 111 urinary isolates of Enterobacteriaceae, 40 isolates of E. coli, 39 isolates of K. pneumonia and 32 isolates of Enterobacter were identified. The antibiotic sensitivity test showed that amikacin and imipinem were the most active antibiotic against all isolates[90%-100%]. While most isolates were resistant to ampicillin [95%- 100]. The phenotypic detection results revealed that 29[72%] of E.coli, 32[82%] of K.pneumoniae and 22[69%] of Enterobacter isolates showed MRHA. MSHA was defected in 11[28%] isolates of E.coli. 7[18%] of K.pneumoniae and in 10[31%] of Enterobacter isolates. Serum resistance was seen in 15[37%] o f E.coli, 13[33%] of K.pneumoniae and 7[21%] of Enterobacter isolates. Biofilm formation was observed in 27[67%] of both E.coli and K. pneumoniae and in 30[94%] of Enterobacter isolates. All E.coli isolates were negative lipase and protease producers, while 16[33%] of K.pneumoniae isolates showed lipase production and one isolate showed protease production. For Enterobacter, none of isolates produce lipase, while 4[12%] of isolates were protease producers. All isolates showed no lecithinase production. For genotypic detection, it was observed that among E.coli isolates, 69% were positive for papC gene, 31% were positive for fimH gene, 30% were positive for iss gene and 77% were positive for biofilm gene. For K.pneumoniae, papC gene was detected in 80% of isolates, 20% were positive, for fimH gene, 8% were positive for iss gene and 87% contained the biofilm gene. Results of Enterobacter isolates were 89%, 11 %, 5% and 95% positive for genes of papC, fimH, iss and biofilm respectively
Conclusion: the present study shows the significance role of virulence factors in urinary tract infections caused by Enterobacteriaceae and the genotypic characterization was more prominent compared to the phenotypic detection of these virulence factors