Lactose vs Non-Lactose Fermenting E. coli: Epidemiology, Clinical Outcomes, and Resistance

BACKGROUND: E. coli are facultative anaerobic, Gram-negative bacilli that will ferment lactose to produce hydrogen sulfide. Up to 10% of isolates have historically been reported to be slow or non-lactose fermenting, though clinical differences are unknown. The aim of our study was to determine whether differences exist between non-lactose (NLFEC) and lactose fermenting E. coli (LFEC) in regards to epidemiology, pathogenicity, clinical manifestations, and antibiotic resistance. METHODS: Retrospective chart review from January 2013 to April 2016 of 150 NLFEC isolates age matched to 150 LFEC isolates from adult patients admitted to Albert Einstein Medical Center in Philadelphia PA. Mann–Whitney U analysis of data was done utilizing SPSS Statistics 24.0 (IBM Corporation) Only the 1st isolate from an admission was included unless the same isolate was found in different cultures drawn at same time. A recurrent isolate from a patient would only be considered if separated by 3 months. Urine cultures with multiple different organisms, cultures with multiple species of E. coli, or multiple cultures w/ E. coli with variable fermentation of lactose were excluded. RESULTS: There were no epidemiological risk factors for isolation of NLFEC from patients. Diabetic patients and patients with CKD had more NLFEC isolates, though the difference was not statistically significant NLFEC isolates were more likely to be found in patients admitted from the community (97% vs 73% P = 0.03) rather than hospital acquired (3% vs 27% P = 0.009). There was no difference in rates of colonization (36% vs 46% P = 0.14) and pathogenicity (64% vs 54% P = 0.256), nor site of infection. NLFEC demonstrated a trend to statistical significance to be less resistant to later generation Cephalosporin. They were less likely to be resistant to Cefepime (1% vs 8% P = 0.003) and be flagged as an ESBL isolate. CONCLUSION: Non-Lactose Fermenting E. coli are more likely to be isolated from patients in the community, have no difference in predilection for nor site of infection, and are less likely to be resistant to later generation Cephalosporins DISCLOSURES: All authors: No reported disclosures.