Case Presentation: A 67-year-old male with a past medical history of COPD and atrial fibrillation was admitted for acute hypoxic respiratory failure. The patient was discovered to have community-acquired pneumonia along with blood cultures positive for Group A Streptococcus and Enterococcus faecalis. A transthoracic echocardiogram (TTE) was negative for vegetations. The patient received IV penicillin while hospitalized and was discharged on 2-week course of amoxicillin-clavulanate. Two months later, the patient presented to the emergency department with a temperature of 38.1 and nausea, vomiting, and body aches. Despite his fever, initial workup was unremarkable for acute infection and the patient was sent home with strict return precautions. The following day, blood cultures grew Enterococcus faecalis and the patient was admitted for further management. The patient was started on ampicillin and ceftriaxone. A repeat TTE was negative for vegetations. A transesophageal echocardiogram (TEE) was subsequently performed which demonstrated a vegetation on the bicuspid aortic valve. Colonoscopy was performed which revealed two polyps, however, they were not resected as the patient was on anticoagulation for atrial fibrillation. The patient was ultimately discharged with a 6-week course of ceftriaxone with penicillin G.
Discussion: E. faecalis IE has a predilection for older populations with comorbidities, however, it is a difficult condition to identify because symptoms on presentation are non-specific. Once blood cultures return positive, consideration of the work-up for IE should be made. A recent study showed that E. faecalis bacteremia had an IE prevalence as high as 26% and that TEE found vegetations in half of the cases where a TTE was negative. Our case highlights the superiority of TEE to identify valvular vegetations. Therefore, we recommend that TEE should be considered in all patients with enterococcus bacteremia as first-line IE work-up or after a negative TTE, especially in those who are older with comorbid conditions. Another consideration when faced with enterococcus IE, is its association with colorectal cancer. In one study, colorectal neoplasm was found in nearly half of patients who had enterococcus IE with an unclear source. Therefore, we recommend that patients without a clear source of infection undergo a colonoscopy to evaluate for malignancy. Our patient did not have a clear source for his IE and therefore underwent colonoscopy which found polyps. Single-agent beta-lactam antibiotics do not have bactericidal activity and are less effective at penetration of biofilms that are prevalent with E. faecalis. Since 1984, the first-line regimen for treatment of enterococcus IE has been a beta-lactam coupled with gentamycin for 4-6 weeks. However, given the increasing resistance to gentamycin and concern for nephrotoxicity, the treatment has shifted to dual beta-lactam therapy, such as ampicillin and ceftriaxone or in our patient’s case, penicillin G and ceftriaxone.
Conclusions: In summary, there are three considerations that should be taken when faced with enterococcus IE. First and foremost, TEE should be considered in all patients with enterococcus bacteremia as first-line IE work-up or after a negative TTE Secondly, if a patient with enterococcus bacteremia has an unclear source of infection, a colonoscopy should be performed in order to evaluate for malignancy. Lastly, treatment for enterococcus bacteremia should consist of dual-beta lactam therapy.