A 55-year-old Honduran man with a past medical history of non-ischemic cardiomyopathy due to valvular heart disease with associated combined heart failure (ejection fraction 40%, stage III diastolic dysfunction), a recent bioprosthetic mitral valve replacement with tricuspid valve repair (2 months prior to admission), and paroxysmal atrial fibrillation presented to our hospital with 3 weeks of subjective fevers, night sweats, 30-pound weight loss, fatigue, and anorexia. One month prior to this presentation, the patient was briefly admitted following his valve replacement surgery with a day of watery diarrhea and was found to be in septic shock due to E. coli bacteremia of uncertain source. Evaluation during this admission included an unremarkable urinalysis and urine cultures and CT imaging only notable for distention and mild dilation of the small bowel suggestive of possible enteritis. Stool studies were not obtained given the self-limited nature of his antecedent diarrheal illness, but serum Strongyloides serologic testing was notably negative at the time. After a brief parenteral antimicrobials course, he was instructed to complete a two-week course of oral cefpodoxime 200 mg q12h upon discharge for transient bacteremia from a presumed self-limited gastrointestinal source.
He did well clinically for one week after discharge before developing subjective fevers with generalized myalgias despite his outpatient cefpodoxime course. Over the following 3 weeks the patient progressively declined with more frequent subjective fevers, night sweats, malaise, anorexia with weight loss, and abdominal fullness further prompting another presentation to the emergency department. He denied sternal wound pain or drainage and a thorough review of systems for other localizing infectious symptoms was otherwise negative.
On admission, vital signs were notable for a temperature of 38.8  C (101.8  F), blood pressure 91/62 mm Hg, heart rate 84 beats per minute, respiratory rate 21 breaths per minute, and oxygen saturation 100% on room air. Physical examination revealed an irregularly irregular heartbeat without murmur and an unremarkable lung exam. His abdomen was soft, nondistended, nontender to palpation, and no organomegaly was noted. No distal extremity edema or distal embolic phenomena were noted on skin exam. Notably, a stage 2 sacral wound that had developed following his valve surgery had healed completely since his prior admission. Laboratory tests were significant for a leukocytosis with a white blood cell count of 14000 (normal 4500-11000 cells/mul), anemia with a hemoglobin of 9.4 (normal 13.5-17.5 gm/dL), and normal kidney and liver function on complete metabolic panel. Inflammatory markers were elevated with a sedimentation rate of 119 mm/hour (normal 0-20 mm/hr). Urinalysis and culture were again unremarkable.
Chest radiograph showed no evidence of acute cardiopulmonary disease, and an initial transthoracic echocardiogram showed no obvious vegetations or compromise of his prosthetic valve. The patient was started on broad spectrum antimicrobials with intravenous vancomycin 1 g q12h and cefepime 2 g IV q8h at the time of admission. Antibiotics were quickly narrowed to cefepime alone after admission blood cultures ultimately grew gram-negative rods in 4/4 collection tubes which later speciated as Escherichia coli. He was transitioned to ceftriaxone 2 g IV q24 based on sensitivity data, but blood cultures remained persistently positive on hospital day 2 and 3 raising concern for an endovascular nidus of infection. Transesophageal echocardiogram was obtained on hospital day 5 which revealed a small 3 mm mobile, filamentous vegetation on the anterior cusp of the prosthetic mitral valve without significant valvular compromise. As a result, he met Duke criteria for diagnosis of infective endocarditis by fulfilling one major criterion (TEE demonstrating a vegetation) and three minor clinical criteria (persistent fevers, predisposing cardiac condition, and persistently positive cultures.).
Antimicrobial therapy was tailored to combination therapy with ongoing ceftriaxone 2 g IV q24h and gentamicin 5 mg/kg IV q24h which was adjusted continually based on levels of accumulation and changes in renal function. He continued to improve clinically, and blood cultures demonstrated complete clearance on hospital day 5. Given that the patient lacked evidence of an antecedent urinary tract infection as the source of his recurrent bacteremia, additional imaging was obtained to exclude a secondary source or nidus of infection. This included CT of the chest, abdomen, and pelvis to exclude an indolent abscess and doppler ultrasounds of the extremities and portal vasculature to exclude septic thrombophlebitis. An MRI of the full spine was also performed to exclude osteomyelitis/discitis given his prior sacral wound during his previous hospitalization. Imaging studies were only notable for mild periappendiceal stranding concerning for a possible site of antecedent inflammation as the source of his recurrent E.coli bacteremia. Given a benign abdominal exam, surgical consultants did not feel he met criteria for acute appendicitis and declined intervention. Neither a colonoscopy nor capsule endoscopy were performed during his inpatient stay owing to limitations on endoscopic procedures performed during a concurrent coronavirus pandemic surge. Given the patient's rapid clinical improvement on tailored antimicrobial coverage, cardiothoracic surgery concluded that the risks of redo-valve replacement outweighed the benefits as there were no significant valvular defects noted on echocardiogram.
The patient subsequently completed a six-week course of combination antimicrobial therapy with appropriate levels of gentamicin and no adverse sequelae of therapy. Repeat echocardiogram showed a largely unchanged small mobile vegetation on the anterior cusp of the prosthetic mitral valve without valvular compromise. He was reassessed by cardiothoracic surgery who again recommended conservative management with chronic oral suppression and additional echocardiographic follow-up given his overall clinical improvement without significant valvular compromise on serial echocardiograms. He was subsequently transitioned to suppressive therapy with trimethoprim-sulfamethoxazole given the presence of continued vegetation on his prosthetic valve with plans for withdrawal after a distant repeat echocardiogram at 6 months of follow-up. The patient was reevaluated several weeks post-discharge and remained clinically well. Unfortunately, he was not seen again in follow-up at our clinic since he returned to his home country of Honduras for continuity of care.