Understanding the Role of Enteropathogenic Escherichia coli (EPEC) in Immunosuppressed Cancer Patients

Adilene Olvera, The University of Texas School of Public Health


Background: Multiplexed nucleic acid amplification tests (NAAT) are becoming widely utilized for the diagnosis of bacterial diarrhea in the US and include probes specific for EPEC. However these platforms do not differentiate typical EPEC (tEPEC, defined as strains carrying eaeA and bfp) which have strong epidemiologic associations with diarrhea from atypical EPEC (aEPEC, defined as carrying eaeA but not bfp) for which the association with diarrhea is less strong. Emerging data suggests that aEPEC subsets carrying efaI/lifA which encodes for adherence factor 1/lymphocyte inhibitory factor A are associated with diarrheal disease. The role of EPEC and its subtypes as agents of bacterial diarrhea have not been well defined in US cancer patients. Methods: We sought to characterize EPEC subtypes in a case control study that included healthy individuals with no diarrhea (HI, N=21), Patients with diarrhea and negative Biofire NAAT for enteropathogens (ND, N=25) and patients with NAAT positive for EPEC (ID, N=52). Quantitative PCR was performed in stools using probes specific for eaeA, efaI/lifA. The qPCR dynamic range was optimized to detect from 5.6X101-5X10 7 bacteria/mg stool setting the cutoff limit of 35 cycle thresholds (CT) for eaA and 32 for efaI/lifA. EPEC strains recovered from stool cultures from DP patients were tested for eaeA and bfp, stx and other diarrheagenic E. coli virulence factors. Results: All EPEC recovered in culture were aEPEC. Fecal qPCR identified eaeA in 3/21 (14%) HI, 0/25 ND (0%) and in 43/52 (83%) ID patients; P<0.001. aEPEC carrying efa1/lifA were found in 0/25 DN patients and in 14/54 (26%) PD; p<0.001. Conclusions: aEPEC carrying adherence factor 1/lymphocyte inhibitory factor A were not present in healthy individuals but were present in a subset of patients with aEPEC associated diarrhea. Additionally, that post-stem cell transplant patients are more likely to encounter EPEC infections. Higher loads of EPEC bacteria were found in cancer patients that in healthy asymptomatic individuals.

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Recommended Citation

Olvera, Adilene, "Understanding the Role of Enteropathogenic Escherichia coli (EPEC) in Immunosuppressed Cancer Patients" (2018). Texas Medical Center Dissertations (via ProQuest). AAI10811321.