1100. Characterization of Enteropathogenic Escherichia coli (EPEC) in Cancer Patients With Diarrhea

Abstract

BackgroundBiofire FilmArray multiplexed nucleic acid amplification tests (NAAT) for bacterial diarrhea include probes specific for EPEC. However, the platform does not differentiate typical EPEC (tEPEC, defined as carrying eaeA and bfp) which have strong epidemiologic associations with diarrhea from atypical EPEC (aEPEC, carrying eaeA but not bfp) for which there is a weaker association. Nevertheless, emerging data suggest that aEPEC subsets carrying efa1/lifA which encodes for adherence factor 1/lymphocyte inhibitory factor A, are associated with diarrhea. The role of EPEC and its subtypes as agents of bacterial diarrhea have not been well defined in immunosuppressed and cancer patients.MethodsWe characterized EPEC subtypes in stools from healthy individuals with no diarrhea (HI, N = 21), cancer patients with diarrhea and negative NAAT (DN, N = 25) and patients with diarrhea positive NAAT for EPEC (DP, N = 54). EPEC isolated from stool cultures were tested for eaeA and bfp, stx and other E. coli pathotypes. We estimated the number of fecal EPEC using a qPCR for eaeA, efa1/lifA that detected 5.6 × 101 to 5 × 107 cfu/mg of stool.ResultsDemographic characteristics and underlying malignancy were similar between DN and DP groups. DP were more likely to have diarrhea on admission than DN [46/52 (88%) vs. 13/25 (52%), P < 0.01]. Stool cultures confirmed EPEC in 24/52 (60%) DP of which 23/24 (96%) were aEPEC. Fecal qPCR for eaeA confirmed EPEC in 43/52 (83%) of DP, 0/25 DN and in 3/21 (14%) of HI (P < 0.001). DP excreted a higher number of EPEC cfu/mg of stool than HI (median 168 vs. 1.18 cfu/mg, P < 0.001) and only DP excreted EPEC efa1/lifA (+) [14/52 DP (27%) vs. 0/25 DN and 0/21 HI; P < 0.001]. When compared with DP EPEC efa1/lifA (-), DP EPEC efa1/lifA (+) had a longer median duration of illness (3 days vs. 1 days, P < 0.05); more likely to be hematopoietic stem cell transplant recipients [7/14 (50%) vs. 7/38 (18%), P < 0.05] and had a higher EPEC eaeA fecal burden (median 3885 vs. 84 cfu/mg, P < 0.05). Co-infections with other pathogens were equally represented in efa1/lifA (−) and efa1/lifA (+) DP subgroups [8/14 (57%) vs. 21/38 (55%) P = NS].ConclusionMost EPEC in cancer patients with diarrhea are aEPEC acquired in the community and when carrying efa1/lifA (+), are associated with more severe disease.Disclosures All authors: No reported disclosures.