E. coli Sepsis: Red Flag for Colon Carcinoma

Abstract

Introduction: While the relationship between Streptococcus bovis bacteremia and colon cancer has been well established, rare cases of colon adenocarcinoma have been reported after exposure to other microorganisms. We present an atypical case of newly diagnosed colon cancer and provide insight into the infectious predispositions of E. coli bacteremia to the development of colon adenocarcinoma. Case Report: A 66-year-old female with past medical history of hypertension, type 2 diabetes mellitus, and obesity was evaluated for one week symptoms of subjective fevers, chills and lower back pain. Upon initial evaluation, her temperature was 101 degrees Fahrenheit with a white count of 12,000 K/mm3, procalcitonin level of 29.02 K/mm3, and lactic acid of 4.8 MMOL/L. Initial septic workup was positive for E. coli bacteremia. The patient was started on Aztreonam (due to her Penicillin allergy). Repeat blood culture 48 hours later on antibiotics was negative for any growth. However, later during hospital stay blood culture was repeated due to SIRS, which was positive again for E. coli. The patient reported no abdominal complaints other than chronic constipation. The patient had cholecystectomy done many years ago. No family history of colorectal cancer and never had a colonoscopy. CT scan of the chest/abdomen/pelvis with contrast revealed no signs of colitis however; it was remarkable for spondylitis/diskitis with adjacent fluid collection at L4-L5. The patient underwent a CT guided aspiration biopsy of the L4-L5 discitis and adjacent fluid collection, showed no growth on culture. Without clear etiology for recurrent E. coli bacteremia ultimately colonoscopy was performed which showed an ulcerated mass in the cecum. Biopsy showed moderately differentiated adenocarcinoma. Discussion: CRC presenting as a persistent E. coli bacteremia is rare. Molecular research has supported the relationship between the virulent E. coli strains and the development of CRC. E. coli strains B2 and D produce cyclomodulin toxins as part of their virulence, which interfere with the cell cycle regulation, promoting chromosomal instability, and increasing susceptibility to the cancer. Enteropathogenic E. coli was reported to down regulate expression of key DNA mismatch repair proteins MSH2 and MLH1. hly+ type 1- E. coli is also associated with adenoma and CRC development. The patients with recurrent E. coli bacteremia with an unknown source, colonoscopy should be done to look for colon tumor.