Streptococcus anginosus purulent pericarditis with cardiac tamponade after coronary artery bypass surgery

Abstract

Purulent pericarditis caused by Streptococcus anginosus is extremely rare. A 66-year-old man underwent elective coronary artery bypass surgery. This was complicated by sternal wound dehiscence with drainage. Subsequently, he developed fever, progressive dyspnoea and presyncope. Echocardiography showed a large pericardial effusion with evidence of tamponade. He underwent emergent pericardiocentesis. The pericardial fluid culture grew S. anginosus. He was treated with 4 weeks of intravenous ceftriaxone with complete clinical recovery. The source of infection was most likely the sternal wound which was overlooked during debridement and rewiring surgery.

Background

Acute purulent bacterial pericarditis is rare in the modern antibiotic era. In this report, we describe an extremely rare case of purulent pericarditis caused by Streptococcus anginosus in a patient after coronary artery bypass surgery.

Case presentation

A 66-year-old man with a medical history of uncontrolled type 2 diabetes, hypertension, hyperlipidaemia, obesity, diastolic heart failure and coronary artery disease status postpercutaneous coronary intervention initially presented with recurrent chest pain. Invasive coronary angiography showed three-vessel coronary artery disease. He underwent elective coronary artery bypass surgery.

Two weeks after the bypass surgery, he sneezed hard and felt something popped in his chest. Subsequently, he noted subjective fever. The sternal wound opened and he had drainage from the wound. He was admitted for sternal wound dehiscence and underwent debridement and rewiring. The surgeon reported that there was no evidence of infection of the wound and there was no culture sent.

The patient continued to have drainage from sternal wound with low-grade fever. He experienced progressive shortness of breath and came to the emergency department with near syncope 6 weeks after the bypass surgery.

Investigations

A 12-lead ECG revealed sinus tachycardia with low voltage. Chest X-ray showed enlarged cardiac silhouette (figure 1A). Transthoracic echocardiography showed a large anterior and lateral pericardial effusion with evidence of tamponade (figure 1B–D and videos 1–3). Laboratory workup showed no leucocytosis. However, the inflammatory markers including erythrocyte sedimentation rate and C-reactive protein were elevated.

Figure 1.

(A) Chest X-ray before pericardiocentesis showing significantly enlarged cardiac silhouette. (B–D) Transthoracic echocardiography showing a large pericardial effusion. (E) Chest X-ray during follow-up showing normal cardiac size. (F–H) Transthoracic echocardiography showing pericardial effusion resolved after treatment. (B and F) Parasternal short-axis view; (C and G) apical four-chamber view; (D and H) subcostal view.

Video 1.

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DOI: 10.1136/bcr-2020-235862.video01

Video 2.

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DOI: 10.1136/bcr-2020-235862.video02

Video 3.

bcr-2020-235862supp003.mp4 ^{(8.5KB, mp4)}

DOI: 10.1136/bcr-2020-235862.video03

Differential diagnosis

The differential diagnosis includes postpericardiotomy syndrome, idiopathic pericarditis and purulent pericarditis. All three diseases can present with fever, elevated inflammation markers and pericardial effusion. However, the predominant symptom for postpericardiotomy syndrome and idiopathic pericarditis is chest pain. The definitive differential relies on pericardial fluid analysis in difficult cases.

Treatment

He underwent emergent pericardiocentesis with 800 mL sanguineous fluid drained. The Gram stain of the pericardial fluid showed Gram-positive cocci in chains and the fluid culture grew S. anginosus. He was treated with 4 weeks of intravenous ceftriaxone.

Outcome and follow-up

At 4 week follow-up, the patient reported a complete resolution of symptoms. Chest X-ray showed normal cardiac size (figure 1E). Repeated echocardiography showed near-complete resolution of the pericardial effusion (figure 1F–H and videos 4–6).

Video 4.

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DOI: 10.1136/bcr-2020-235862.video04

Video 5.

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DOI: 10.1136/bcr-2020-235862.video05

Video 6.

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DOI: 10.1136/bcr-2020-235862.video06

Discussion

Purulent pericarditis is a localised infection within the pericardial space often caused by bacteria. It has become a rare disease in the modern antibiotic era with an incidence of approximately 1 in 18 000.¹ The major complications of purulent pericarditis include sepsis, cardiac tamponade and haemodynamic collapse in the acute phase. The survivors may suffer from constrictive pericarditis, mycotic aneurysms of the aorta, coronary artery and left ventricle in the long run.^{2 3} Common organisms of purulent pericarditis include Staphylococcus aureus, S. pneumoniae and Haemophilus influenzae.^{4 5} S. anginosus is a very rare cause of purulent pericarditis. In the past four decades, only about 20 such cases have been reported worldwide.^{6 7}

Streptococcus anginosus and its related species, S. intermedius and S. constellatus, form the S. anginosus group. These organisms are a part of normal commensal flora of the oral cavity, gastrointestinal tract and genitourinary tract. However, they can cause various infections such as abscesses, endocarditis and bacteraemia.^{8 9} Most patients have a predisposing condition such as immunosuppression or malignancy.¹⁰ We report the first case of S. anginosus purulent pericarditis after elective coronary bypass surgery. We reviewed serial chest X-rays and found that the patient had significantly enlarged cardiac silhouette right after the bypass surgery suggesting the presence of a large amount of pericardial effusion as a surgical complication. The echocardiography showed a large anterior and lateral pericardial effusion instead of a circumferential distribution pattern, suggesting that the pericardial effusion is more related to the surgery than from the infection itself. Pericardial fluid serves as an excellent growth media for the bacteria.

The pericardial space is rarely a primary site of bacterial infection without underlying infection elsewhere. Instead, bacterial pericarditis usually occurs as a secondary infection by direct spreading from a surrounding intrathoracic infection or by haematogenous dissemination from a distant focus of infection.^{4 5} In our case, the infection most likely originated from the sternal wound infection following sternal dehiscence. The patient reported fever and sternal wound drainage for which he underwent debridement. However, no tissue culture was sent and he did not receive antibiotic therapy. It is logical to postulate that the infection subsequently extended from the sternal wound to the pericardial space causing purulent pericarditis.

Purulent pericarditis due to S. anginosus group organisms is a rapidly progressive and life-threatening condition.⁷ Effective treatment requires expeditious drainage of the infected pericardial fluid and culture-specific antibiotics. Even with drainage and antibiotics, the mortality rate is still high. Some patients may require repeated drainage, intrapericardial thrombolytics and pericardiectomy given the loculated nature of S. anginosus group infections. S. anginosus group organisms are broadly susceptible to most β-lactams.¹¹ Most patients have been treated successfully with 2–4 weeks of intravenous antibiotic therapy.

Learning points.

• Streptococcus anginosus group bacteria are a part of normal commensal flora capable of causing purulent pericarditis, although it is very rare. Recent cardiac surgery with pericardial effusion is a predisposing condition.

• Early recognition and timely management of intrathoracic focus of infection may prevent infection from spreading to the pericardial space and subsequent purulent pericarditis.

• Due to the high mortality rate with purulent pericarditis, a high index of suspicion is needed for early diagnosis to initiate appropriate therapy including pericardial drainage and antibiotics.