Ubi pus ibi evacua: Staphylococcus aureus pericardial abscess--one more dreadful complication of this pathogen.

Pericardial abscess is an extremely rare complication of Staphylococcus aureus bacteremia, with very few case reports published in the English literature. Delayed diagnosis of this entity may carry severe complications to the patient. The main treatment of a pericardial abscess is percutaneous drainage under echocardiographic or tomographic guidance, or surgical drainage and pericardiectomy, in conjunction with appropriate antimicrobial therapy.

The article by El-Ahdab et al (1) in this issue of the journal provides an important reminder about the virulence of S. aureus. The article describes a young cirrhotic patient with community-acquired Staphylococcus bacteremia and a secondary focus of infection (a pericardial abscess). The patient required surgical pericardiectomy and a long course of antimicrobial therapy for cure.

The natural history of S. aureus bacteremia (SAB) in the preantibiotic era showed young persons without comorbidities, with frequent metastatic lesions and mortality approaching 82%. (2) Despite advances in antibiotic therapy, mortality in the modern era has remained elevated at around 20 to 35%. (3) SAB can be a community-, nursing home-, or hospital-acquired infection. Patients with community-acquired SAB have higher rates of unknown primary foci of infection and higher metastatic complications. Several clinical questions always arise when dealing with SAB. First, Are positive blood cultures true bacteremia? Three quarters of the time, positive blood cultures with S. aureus are considered true bacteremia. (4) Second, What is the type of bacteremia in this case? In 1976, Nolan and Beaty (5) described two different groups with SAB. One group, without an identifiable site of primary infection, acquired bacteremia in the community. Secondary metastatic foci of infection developed in 95% of patients. The second group consisted of older patients with an identifiable primary site of infection. Secondary foci appeared in only 10% of patients. Most recently, Fowler et al (6) described four types of SAB, based on clinical and echocardiographics findings. To evaluate patients appropriately, all removable sources of infection must be taken off, surveillance blood cultures should be procured on Days 2 to 4 of adequate antimicrobial therapy, and a transesophageal echocardiogram (TEE) should be carried out on Days 5 to 7 of antimicrobial treatment. Afterward, patients were classified as having simple bacteremia, uncomplicated bacteremia, endocarditis, or deep tissue extracardiac disease. Simple bacteremia requires a negative TEE, negative surveillance cultures, source of infection resolved, rapid clinical improvement, no prosthesis present, and no evidence of metastatic foci of disease. Uncomplicated bacteremia requires TEE with valvular lesions but without endocarditis, growth of S. aureus in a surveillance blood culture, a nonremovable superficial skin focus of SAB, or clinical signs of disease after 3 days of antimicrobial therapy. Infective endocarditis was defined according to the Duke criteria. Extracardiac disease refers to deep-seated infections such as osteomyelitis and mediastinitis.

Third, What is the optimal duration of therapy? Based on the above types of SAB, 7 days is recommended for simple bacteremia, 14 days for uncomplicated bacteremia, and 4 to 8 weeks for the last two groups.

Aulus Cornelius Celsus (c. 25 BC-50 AD) was a Roman encyclopedist whose work De re Medicina was most likely from Hippocratic writers. In today's world of high technology and very effective antimicrobials, Celsus' old dictum, ubi pus ibi evacua (where there is pus, there evacuate), remains a very critical therapy for any kind of abscess.

Lastly, it is important to recognize the usefulness of the infectious diseases consultation in cases with SAB. (6) We should not underestimate S. aureus as an ordinary pathogen.

References

(1.) El-Ahdab F, East M, Sexton D, et al. Staphylococcus aureus pericardial abscess in a patient with liver cirrhosis: Case report. South Med J 2003; 96:926-927.

(2.) Skinner D, Keefer C. Significance of bacteremia caused by Staphylococcus aureus: A study of 122 cases and a review of the medical literature concerned with experimental infections in animals. Arch Intern Med 1941; 68:851-875.

(3.) Willcox PA, Rayner BL, Whitelaw DA. Community-acquired Staphylococcus aureus bacteraemia in patients who do not abuse intravenous drugs. QJM 1998:91:41-47.

(4.) Weinstein MP, Towns ML, Quartey SM, et al. The clinical significance of positive blood cultures in the 1990s: A prospective comprehensive evaluation of the microbiology, epidemiology, and outcome of bacteremia and fungemia in adults. Clin Infect Dis 1997;24:584-602.

(5.) Nolan CM, Beaty HN. Staphylococcus aureus bacteremia: Current clinical patterns. Am J Med 1976;60:495-500.

(6.) Fowler VG Jr, Sanders LL, Sexton DJ, et al. Outcome of Staphylococcus aureus bacteremia according to compliance with recommendations of infections diseases specialists: Experience with 244 patients. Clin Infect Dis 1998;27:478-486.

From the Department of Medicine, Danbury Hospital, Danbury, CT.

Reprint requests to Juan-Pablo Caeiro, MD, Department of Medicine, Danbury Hospital, 70 Main Street, Danbury, CT 06810. Email: [e-mail]

Accepted June 2, 2003.

Copyright [c] 2003 by The Southern Medical Association

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