An unique presentation of infective endocarditis

Abstract

This lesson reports the case of endophthalmitis, a rare presentation of infective endocarditis (IE), two months following cardiac surgery. Although inflammatory markers were increased, blood cultures were negative. Transoesophageal echocardiography demonstrated an aortic root abscess. Culture of tissue obtained at surgery revealed the infective organism to be Aspergillus fumigatus, a rare cause of IE in the immunocompetent patient.

Key learning points

• Aspergillus endocarditis is an ominous complication after cardiac surgery and confers a poor prognosis.

• The diagnosis of fungal endocarditis is difficult, leading to delays in treatment, but should always be considered in ‘culture-negative’ endocarditis, especially in patients with prosthetic cardiac valves.

• Patients with pyrexia of unknown origin following valve replacement should undergo transthoracic echocardiography (TTE) and transesophageal echocardiography (TOE), and several sets of blood cultures.

• Endophthalmitis is a rare but recognised complication of endocarditis.

Lesson

A 73-year-old man underwent tissue aortic valve replacement (AVR). Despite initial uncomplicated recovery, one-month postoperatively he reported reduced right-sided visual acuity. Ophthalmological examination suggested a diagnosis of unilateral endophthalmitis. On examination he was pyrexial (38^oC) and had aortic regurgitation (AR) but no other signs of endocarditis. Investigation revealed normocytic normochromic anaemia (haemoglobin 9.5 g/l), white cell count 9×10⁹/l, C-reactive protein 71 mg/l. Six blood cultures were negative at five days, as were vitreous cultures. Atypical respiratory serology and antistaphylococcal antibodies were negative. Transoesophageal echocardiography demonstrated an aortic root abscess posteriorly (Fig 1). The prosthetic AV was ‘rocking’ with moderate AR.

Fig 1.

Transoesophageal echocardiography demonstrating an aortic root abscess posterior to the prosthetic aortic valve.

A diagnosis of infective endocarditis (IE) with secondary endopthalmitis was made and treatment commenced with intravenous vancomycin, gentamicin and rifampicin, intra-vitreal cefatazidine, topical chloramphenicol and oral predsnioslone. His case was discussed with the cardiothoracic surgery team and it was agreed that, in the absence of cardiac compromise, surgery should be delayed until he had received a prolonged course of antibiotics. One week later he developed left-sided endophthalmitis. Intravenous variconazole was added to cover for fungal endophthalmitis. In view of ongoing infection, he underwent redo-AV surgery. At surgery, large vegetations were seen on the partially dehisced bioprosthetic valve with a gross sub-annular root abscess extending into the left ventricular outflow tract. The patient underwent aortic root replacement and bioprosthetic AVR. Samples of the explanted valve grew Aspergillus fumigatus and intravenous amphotericin was commenced. Two days postoperatively the patient's condition deteriorated suddenly with the development of intracerebral haemorrhage, followed by multi-organ failure and he died the following day.

Discussion

Fungal endocarditis is rare, accounting for 1.3% of all cases of endocarditis and affecting only 0.1% of all prosthetic valves. The most common organism isolated is Candida, with Aspergillus cultured in 25% of cases.¹ Aspergillus typically affects the immunocompromised but rarely affects immunocompetent patients. Additional predisposing factors include prior valve surgery, diabetes, malignancy, in-dwelling intravascular catheters, broad-spectrum antibiotics and intravenous drug abuse.² The diagnosis is often delayed³ due to paucity of peripheral signs of IE and a lack of consistent or pathognomonic features. The common features include fever and peripheral emboli (seen in 83% of patients) involving all major organs and associated with aneurysm formation. Blood cultures are generally negative with positive cultures in only 31% of Aspergillus cases.² Often the diagnosis is made at surgery. The prognosis is poor with a high rate of recurrence and survival rate of only 18%.²

Ocular manifestations are seen in fungal endocarditis in approximately 13% of cases, but Aspergillus endophthalmitis secondary to endocarditis is extremely rare.⁴ Treatment is with systemic and intra-vitreal antibiotics and, in severe cases, vitrectomy.