1637 Bacterial Enteritis as a Red Herring in Workup for Fever of Unknown Origin

Abstract

INTRODUCTION: The evaluation for fever of unknown origin (FUO) can often be misled by anchoring on incidental findings. Here, we describe the case of a patient with a FUO and new-onset diarrhea incidentally found to have a bacterial colitis. CASE DESCRIPTION/METHODS: A 72-year-old female was seen by the Gastroenterology consult service for new-onset of diarrhea in the context of 2-3 weeks of fevers, leukocytosis, and malaise. CT revealed colonic wall thickening suggestive of colitis and GI PCR revealed enteroaggregative Escherichia coli (EAEC). Inflammatory markers revealed ESR >130, and CRP 37.7. The patient had persistent fevers and leukocytosis despite antibiotics. PET scan showed no evidence of infection or malignancy. A bilateral temporal artery biopsy was obtained, which showed temporal arteritis (GCA). Fevers resolved with steroids. DISCUSSION: Uncomplicated gastrointestinal infections without abscesses typically do not cause ESR elevations >100. Our patient’s markedly elevated inflammatory markers suggested that EAEC colitis was an unlikely explanation for her diarrhea and fever. Though similar data is lacking in adults, a cohort of children with E. coli enteritis had ESR ranging from 2-48 and CRP from 0.02-10.25 (Kim, Y et al., Infect Chomother, 17 Dec 2017, 275-281). Common etiologies of ESR elevations >100 include infectious (mostly pneumonia, cellulitis, bacteremia, abscesses, or osteomyelitis), autoimmune, and malignancy (Daniels, LM et al., Mayo Clinic Proc., Nov 2017, 1636-1643). Thus, EAEC colitis was a red herring in our workup for our patient with a FUO. A widely used algorithm for FUO (Figure 1) would have suggested that no further workup was necessary for our patient after her CT revealed colitis in the setting of diarrhea and EAEC. We conclude that systemic inflammatory markers may be helpful in patients with suspicion for bacterial enteritis as an etiology of prolonged fevers. In our case, the profoundly elevated systemic inflammatory markers lead us to continue down the algorithm for FUO, leading to our biopsy proven diagnosis of GCA. GCA is most commonly seen in patients >50 years old and should be considered in patients with FUO within this demographic even when symptoms are not present.