Treatment: 
The patient underwent pericardiocentesis then laparoscopic drainage of her perihepatic abscesses and drain placement with extensive hepatic necrosis noted intraoperatively.  She improved clinically and was discharged with ampicillin-sulbactam and doxycycline for a total of eight weeks of antibiotic therapy.
Outcomes and Follow-Up:
She was seen once more in the Infectious Disease clinic and was asymptomatic. She was then lost to follow up before being seen by OB-GYN for evaluation of the tubo-ovarian abscess.
Discussion:
Fusobacteria are an obligate anaerobic, non-spore forming, Gram-negative bacilli that are considered normal flora in the oral cavity. This organism accounts for less than 1% of bacteremia and less than 1% of clinically significant infections (1).Fusobacterium nucleatum is at times a difficult organism to isolate in clinical practice where the bacterium is not easily grown in blood or abscess cultures, but only on PCR or other modalities (12). As in the case above with only the liver aspirate culture with positive growth, patients may present with disseminated infections and have abscesses in multiple organs despite most of the cultures remaining negative. One contributing factor to this culture negativity would be ample pre-culture antibiotics. Although there was no confirmed source for this case’s infection, we assume it was from poor dental hygiene and social history.
Pyogenic liver abscesses (PLA) are the most common form of liver abscess in the United States and are most frequently caused by E. coli  in adults.  Fusobacterium nucleatum  has rarely been reported as a cause of PLA, and to our knowledge, there is only one other reported case of Fusobacterium  PLA associated with pericardial effusion (12).
Cardiac tamponade (CT) is defined as compression of the cardiac chambers due to an increase in intrapericardial pressure. This may be due to accumulation of fluid, pus, blood, clots, or gas within the pericardial space as a result of an effusion, trauma, or rupture of the myocardium (13). While the pericardium does have some degree of elasticity, a rapid accumulation of fluid will lead to a marked increase in intrapericardial pressure that may impede normal cardiac filling and result in cardiovascular collapse. Beck’s triad of hypotension, elevated jugular venous pressure, and muffled heart sounds are the classic presentation of acute CT. However, these features are not always present, especially in subacute tamponade as in our patient. Additional clinical diagnostic factors include tachycardia and pulsus paradoxus. Prompt diagnosis and assessment of acute or subacute CT should be aided by TTE.
There are many echocardiographic signs of CT in addition to the presence of a pericardial effusion. The most sensitive findings include collapse of the right atrium (RA) or right ventricle (RV) and inferior vena cava plethora. Left atrial collapse is also highly specific, but only seen in approximately 25% of hemodynamically compromised patients (14). Additionally, there may be changes in right and left-sided inflow velocities with respiration. Tricuspid E wave velocity variation >60% and mitral E wave velocity variation of >25% by pulsed-wave doppler is highly suggestive of CT (14).
In regards to etiology, infection is a less common cause of tamponade. Multiple studies have demonstrated a rate of 15-24%, however these infections are predominately viral, with bacteria accounting for approximately 3.7% of total cases (15). Common bacteria to cause tamponade include Staphylococcus, Streptococcus, Escherichia coli, Salmonella , and Neisseria meningitides (16). However, despite extensive literature review, we were unable to find a case of a Fusobacterium infection causing tamponade, nor any bacterial liver abscess invading into the pericardium causing tamponade physiology.
Furthermore, this may be the first documented case of a tubo-ovarian abscess (TOA) caused by F. nucleatum. While there are two case reports of TOA caused by F. necrophorum(14,15) there are no published cases of TOA caused by this species of Fusobacterium.
In conclusion, maintaining a broad differential diagnosis during unique clinical presentations is prudent. Fusobacterium nucleatum is considered normal flora in the oral cavity, but when it rarely causes clinically symptomatic infection, its presentation varies widely. In this case, rapid identification of an exceedingly rare and possibly novel case of Fusobacterium nucleatum infection prevented grave hemodynamic collapse in the setting of sub-acute cardiac tamponade and yielded a favorable outcome.
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