E. hirae Causing Biliary Tract Infection in a Patient with Cholangiocarcinoma: A Case Report.

Introduction: E. faecium and E. faecalis are the common species of Enterococcus responsible for the majority of infections. Earlier, species other than the common ones were usually unidentified and reported as Enterococcus species. However, modern equipment, like MALDI-TOF and VITEK2, have been utilitarian, helping us to identify the previously unidentified species. E. hirae is an organism seldom reported to cause human infections. Here, we report a case of a biliary tract infection in a female patient with cholangiocarcinoma caused by E. hirae.

Case: A 56-year-old female presented with fever and abdominal pain. Bile aspirated during the ERCP was received in our laboratory. The gram stain of the bile sample revealed abundant polymorphonuclear leucocytes along with gram-positive diplococci. The organism failed to grow on MacConkey agar. On blood agar, non-hemolytic colonies grew. The organism was identified as E. hirae by MALDI-TOF MS. The antibiotic susceptibility performed using VITEK2 revealed it to be resistant to high-level gentamicin and susceptible to all remaining drugs. She was successfully treated with oral ciprofloxacin for the infection.

Discussion: Bile is colonized with bacteria due to obstruction in the biliary tree, leading to cholangitis. This causes bacterial proliferation and translocation of bacteria into the systemic circulation. Our case was resistant to high-level gentamicin, while all previously reported cases were susceptible. The resistant isolates of E. hirae being isolated from cattle and their surroundings amidst the rampant use of antibiotics in livestock can pose a difficult situation for humans. Thus, there should be regulations on antibiotic usage in livestock. Cases like these should be reported and recognized for their potential to cause outbreaks if they remain unreported.

Conclusion: Thus, E. hirae, when encountered, should not be ignored but considered a pathogen and reported. The presence of drug-resistant organisms in cattle and their surroundings, their zoonotic potential to cause infections in humans, and the uncontrolled usage of antibiotics in livestock are causes for concern. Thus, we need to be more vigilant regarding it in the future.