Discussion
F nucleatum is a gram-negative, nonmotile, spindle-shaped rod found in dental plaques.5 The incidence of F nucleatum bacteremia is 0.34 per 100,000 people and increases with age, with the median age being 53.5 years.6 Although our patient did not present with F nucleatum bacteremia, it is possible that bacteremia was present before hospitalization but resolved by the time the sample was drawn for culture. F nucleatum bacteremia can lead to a variety of presentations. The most common primary diagnoses are intra-abdominal infections (eg, PHA, respiratory tract infections, and hematological disorders).1,6
PHA Presentation
The most common presenting symptoms of PHA are fever (88%), abdominal pain (79%), and vomiting (50%).4 The patient’s presentation of inspiratory right-sided chest pain is likely due to irritation of the diaphragmatic pleura of the right lung secondary to the abscess formation. The patient did not experience abdominal pain throughout the course of this disease or on palpation of his right upper quadrant. To our knowledge, this is the only case of PHA in the literature of a patient with inspiratory chest pain without respiratory infection, abdominal pain, and cardiac abnormalities. There was no radiologic evidence or signs of hypoxia on admission to CWBYVAMC, which makes respiratory infection an unlikely cause of the chest pain. Moreover, the patient presented with new-onset chest pain 2 weeks after the diagnosis of pneumonia.
Common laboratory findings of PHA include transaminitis, leukocytosis, and bilirubinemia.4 Of note, increased procalcitonin has also been associated with PHA and extreme elevation (> 200 μg/L) may be a useful biomarker to identify F nucleatum infections before the presence of leukocytosis.3 CT of PHA usually reveals right lobe involvement, and F nucleatum infection usually demonstrates multiple abscesses.4,7
Contributing Factors in F nucleatum PHA
F nucleatum is associated with several oral diseases, such as periodontitis and gingivitis.8 It is important to do an oral inspection on patients with F nucleatum infections because it can spread from oral cavities to different body parts.
F nucleatum is also found in the gut.9 Any disease that can cause a break in the gastrointestinal mucosa may result in F nucleatum bacteremia and PHA. This may be why F nucleatum has been associated with a variety of different diseases, such as diverticulitis, inflammatory bowel disease, appendicitis, and colorectal cancer.10,11 Our patient had a history of diverticulosis with diverticulitis. Bawa and colleagues described a patient with recurrent diverticulitis who developed F nucleatum bacteremia and PHA.11 Our patient did not have any signs of diverticulitis.
Our patient’s COVID-19 infection also had a role in delaying the appropriate treatment of PHA. Without any symptoms of PHA, a diagnosis is difficult in a patient with a positive COVID-19 test, and treatment was delayed 1 month. Moreover, COVID-19 has been reported to delay the diagnosis of PHA even in the absence of a positive COVID-19 test. Collins and Diamond presented a patient during the COVID-19 pandemic who developed a periodontal abscess, which resulted in F nucleatum bacteremia and PHA due to delayed hospital presentation after the patient’s practitioners recommended self-isolation, despite a negative COVID-19 test.12 This highlights the impact that COVID-19 may have on the timely diagnosis and treatment of patients with PHA.
Malignancy has been associated with F nucleatum bacteremia.1,13 Possibly the association is due to gastrointestinal mucosa malignancy’s ability to cause micro-abrasions, resulting in F nucleatum bacteremia.10 Additionally, F nucleatum may promote the development of colorectal neoplasms.8 Due to this association, screening for colorectal cancer in patients with F nucleatum infection is important. In our patient, a colonoscopy was performed during the patient’s hospitalization for diverticulitis 2 years prior. No signs of colorectal neoplasm were noted
Conclusions
PHA due to F nucleatum is a rare but potentially life-threatening condition that must be diagnosed and treated promptly. It usually presents with fever, abdominal pain, and vomiting but can present with chest pain in the absence of a respiratory infection, cardiac abnormalities, and abdominal pain, as in our patient. A wide spectrum of infections can occur with F nucleatum, including PHA.
Suspicion for infection with this organism should be kept high in middle-aged and older individuals who present with an indolent disease course and have risk factors, such as poor oral health and comorbidities. Suspicion should be kept high even in the event of COVID-19 infection, especially in individuals with prolonged fever without other signs indicating respiratory infection. We believe that the most likely causes of this patient’s infection were his dental caries and periodontal disease. The timing of his symptoms is not consistent with his previous episode of diverticulitis. Due to the mortality of PHA, diagnosis and treatment must be prompt. Initial treatment with drainage and empiric anaerobic coverage is recommended, followed by a tailored antibiotic regiment if indicated by culture, and further drainage if suggested by imaging.