Detection of Virulence Genes in Uropathogenic Escherichia coli by Multiplex Polymerase Chain Reaction(PCR) : Comparison with Clinical Characteristics

Lim, Seong Joon; Kim, So Young; Lim, In Seok; Yoon, Shin Won; Chae, Soo Ahn; Lee, Dong Keun; Choi, Eung Sang; Yoo, Byoung Hoon; Song, Mi Ok; Kim, Won Yong

Abstract

BACKGROUND: We identified virulence genes in uropathogenic E. coli isolates and studied the association between virulence gene and clinical characteristics in order to predict the severity and recurrency.
METHODS
39 Escherichia coli strains from patients with urinary tract infection were clinically and genotypically characterized. The strains were examined genotypically by using the multiplex polymerase chain reaction for presence of 5 urovirulence genes : pyelonephritis-associated pili(pap), S. fimbriae(sfa), afimbrial adhesin(afa), cytotoxic necrotizing factor (cnf), and alpha-hemolysin(hly). The patient's clinical characteristics were determined retrospectively.
RESULTS
17 pap(+), 4 sfa(+), 7 afa(+), 6 cnf(+), and 8 hly(+) strains were identified. And there were 10 genotypes. Among them, genotype pap(+)sfa(-)afa(-)cnf(-) hly(-) was most dominant(36%). But no urovirulence gene was detected in 12 strains(31%). When the data was analyzed, it was apparent that an association among various urovirulence genes exists. sfa gene was frequently associated with cnf gene(p < 0.001). And afa gene was associated cnf and hly gene(p= 0.026, <0.001). An association between cnf gene and hly gene was observed(p=0.002). Positive rates of virulence genes were not different between male and female. In infancy, pap(-)sfa(-)afa(+)cnf(+)hly(+) genotype was dominant. In 2-15 years old age group, pap(-) sfa(-)afa(-)cnf(-)hly(-) genotype was dominant. And in 16- 40 years old age group, pap(+)sfa(-)afa(-)cnf(-)hly(-) was dominant. So, some virulence genotype might be associated with specific age group. Presence of virulence gene or specific genotype was not different among diseases(acute pyelonephritis, cystitis, asymptomatic bacteriuria). So, virulence genes were not associated with severity of urinary tract infection. Virulence genes were not associated with susceptibility of recurrent infection. In neurogenic bladder patients, there were significantly more sfa(+) strains (p=0.019). And all isolates of neurogenic bladder patients were genotype pap(+)sfa(+)afa(-)cnf(+)hly(-)(p < 0.001).
CONCLUSION
In this study, We found which genotype is most dominant in uropathogenic Escherichia coli, and that virulence genes do not suggest severity or recurrency of urinary tract infection. In neurogenic bladder patients, some virulence genes were more prevalent.