Air in the Left Ventricle. An Unusual Case of Endocarditis.

Figure 1. Noncontrast thoracic computerized tomography demonstrated air in the left ventricle. A 59-year-old woman who had recently returned from a trip to Laos presented to the emergency department with decreased appetite, altered mentation, and abdominal pain. Four days before admission, she developed vomiting and nonbloody diarrhea. She was intubated in the emergency department mainly for airway protection and admitted to the intensive care unit. Her medical history included poorly controlled diabetes mellitus and gastroesophageal reflux disease. Physical examination revealed a 2/6 systolic murmur and diffuse abdominal tenderness. Computed tomography of the chest and abdomen showed air in the left ventricle (Figure 1) and within the renal collecting system bilaterally (Figure 2). Blood and urine cultures were positive for gram-negative rods, which were later identified as Citrobacter koseri. The organism was resistant to ampicillin but otherwise was pansensitive. The patient initially was treated with meropenem, which was changed later to ceftriaxone based on culture sensitivity results. Transesophageal echocardiography showed an increased echogenic density of the anterior papillary muscle, with multiple small mobile pockets presumed to be secondary to “gas gangrene” of the myocardial tissue and an echo-dense vegetation in the anterior and posterior mitral leaflets (Figure 3). Transesophageal echocardiography also showed a flail anterior mitral leaflet with severe mitral regurgitation and severe pulmonary hypertension. Magnetic resonance imaging of the brain revealed multiple infarcts compatible with an embolic process. The patient subsequently underwent urgent mitral valve replacement with papillary muscle biopsy and culture. Papillary muscle cultures confirmed C. koseri infection. The postoperative course was complicated by cardiogenic shock, which required multiple vasoactive medications, endophthalmitis, and acute kidney injury, which required continuous renal replacement therapy. The patient’s condition slowly improved, and she ultimately had complete recovery of kidney function. At the time of transfer to a long-term acute care hospital, she continued to have mild cognitive deficits, residual leftsided weakness, and dysphagia. This case has been previously reported in the form of an abstract (1). Citrobacter species, which belong to the Enterobacteriaceae family, are environmental organisms commonly found in soil, water, and the intestinal tracts of animals and humans. Although Citrobacter infections typically occur in hospital settings in patients with multiple comorbidities, they are seldom found in the general population (2). C. koseri is frequently associated with neonatal meningitis and brain abscesses. Both of these conditions have high mortality rates (3). In adults, infections are reported mainly in immunocompromised individuals, although these infections can affect immunocompetent individuals (4). Endocarditis caused by C. koseri is extremely rare. To our knowledge, there are only four previous cases of endocarditis due to C. koseri reported in the English literature. The current case demonstrates a unique example of a gas-forming infection secondary to C. koseri presenting as