Molecular Study of E. coli Virulence Genes in Nosocomial Sepsis

Maysaa E. Zaki*¹, Samah Bastawy² and Karim Montasser²

¹Clinical Pathology, Mansoura Faculty of Medicine, Egypt.

²Clinical Pathology, Helwan Faculty of Medicine, Egypt.

Corresponding Author E-mail: may_s65@hotmail.com

DOI : http://dx.doi.org/10.13005/bbra/2743

ABSTRACT: Escherichia coli (E. coli) is a common cause of nosocomial sepsis. There are multiple factors related to the severity of sepsis among these are the presence of virulence genes and the pattern of antibiotics resistance. The aim of the present study was to determine the prevalence of virulence pap gene encoding for pili, hlyA gene encoding for α-hemolysin and cnf1 gene encoding for cytotoxic necrotizing factor 1 among E. coli isolated from children with nosocomial sepsis. Also, to correlate the presence of ESBL and carbapenem resistance with the presence of these genes. The study is a retrospective cross-sectional study included 150 non-duplicate strains of E. coli isolated from blood cultures from children with nosocomial sepsis. The isolated E. coli strains were subjected to antibiotics study by disc diffusion method, detection of extended spectrum lactamase production by double discs diffusion method and determination of resistance to carbapenem by combined tests methods. The detection of virulence genes pap, hylA and cnf-1 were determined by multiplex polymerase chain reaction (PCR). E. coli isolates were classified as ESBL phenotype in 56% of the isolates and carbapenemase producing phenotype in 34.7%. Pap gene, hylA and cnf-1 genes were detected in 30%, 23.3% and 22.7% of the isolated E. coli. The clinic-laboratory study of the virulence genes of E. coli revealed the significant association of pap, hylA and cnf-1genes with prolonged duration of the use of the medical devices (4.3± 2.9 days-P=0.01, 4.5± 2.9 days, P=0.02, 5.2± 3.4 days, P=0.0001 respectively). HylA gene was associated with younger age of the patients (28.4± 4.5, P=0.01). Pap gene was significantly associated with ESBLs and carbapenemase phenotypes (P=0.0001, P=0.002 respectively). On the other hand, cnf-1 was significantly associated with E. coli isolated from primary sepsis (P=0.02) and in isolates from sepsis due to medical devices (P=0.02) and was significantly associated with death (P=0.01) and carbapenemase resistance (P=0.01). The present study highlights the prevalence of pap, hylA and cnf-1 virulence genes among E. coli associated with nosocomial sepsis in children. The frequency of some of these genes was correlated with extended spectrum lactamase resistance and carbapenemase resistance. This may be attributed to the presence of the virulence and antibiotics genes on transferable plasmids. Moreover, there was association with cnf-1 virulence gene and mortality outcome of sepsis. Further studies are recommended to evaluate these findings.

KEYWORDS: Cnf-1; E. Coli; HylA; Multiplex PCR; Pap

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