Bacterial pericarditis

Article written and reviewed by Dr Luca Moretti

bacterial pericarditis is a disease of the pericardium caused by bacteria, with presentations ranging from rapidly progressive pyogenic infection to subacute forms caused by slow-growing or difficult-to-culture microorganisms. The term identifies an etiology, whereas the definition of purulent pericarditis describes a suppurative process with infected exudate. The two categories overlap substantially but are not perfectly equivalent: a bacterial infection may be recognized before macroscopic pus forms, and a pericardial manifestation associated with a systemic infection may also have an immune-mediated component.

tuberculous pericarditis belongs biologically to bacterial forms, but has distinctive epidemiology, diagnosis, and treatment. In clinical use, the expression bacterial pericarditis is often used mainly for nontuberculous infections. This distinction should be made explicit because antibiotic coverage for pyogenic infections is not adequate treatment for tuberculosis and because the significance of a lymphocytic effusion differs from that of a neutrophilic collection in a septic patient.

The disease is now uncommon in settings with timely access to antibiotics, but remains severe when it occurs. The priority is to recognize infection, assess its effects on cardiac filling, and identify the source. In suppurative forms, antibiotics and drainage are complementary: blood pressure improvement after evacuation does not demonstrate eradication, whereas microbiologically active therapy may fail if an undrained collection persists.

Etiology, routes of spread, and predisposing factors

The most relevant pyogenic bacteria include staphylococci and streptococci, with distribution conditioned by the clinical setting. Staphylococcus aureus is particularly important in bacteremia, healthcare-associated infections, and after procedures; Streptococcus pneumoniae may be associated with pneumonia and intrathoracic spread. Other streptococci, enterococci, and Gram-negative bacilli may be involved, especially in frail patients or in the presence of a specific source. The rarity of the disease and heterogeneity of series do not allow universal microbiologic percentages to be applied to every healthcare facility.

contiguous spread may originate from complicated pneumonia, pleural empyema, mediastinitis, esophageal infection, or nearby collections. In these cases, the pericardium is part of a broader anatomic problem. An effusion during pneumonia is not always infected, but persistent fever, circulatory deterioration, and a complex collection increase suspicion. Identifying the source helps both select antibiotics and determine which compartments require drainage or surgical correction.

hematogenous dissemination may occur during bacteremia from catheters, skin, deep tissues, or other foci. Infective endocarditis and infections of cardiac structures may coexist or contribute to the presentation. Persistently positive blood cultures therefore require investigation for an uncontrolled reservoir and assessment of devices and valves when clinically indicated. The presence of the same organism in blood and fluid strengthens attribution, but positive blood cultures alone do not prove that every effusion is an infected collection.

direct inoculation includes penetrating trauma, thoracic or cardiac surgery, and, less commonly, pericardial procedures. A healthcare-associated setting changes resistance risk and makes local microbiology relevant. Coagulase-negative staphylococci and Cutibacterium acnes may be difficult to interpret because they are also part of skin flora. An isolate should neither be automatically dismissed as contamination nor always considered causal: the number and type of samples, concordant growth, presence of prosthetic material, and clinical picture help define its significance.

Infections caused by anaerobes or polymicrobial infections become more plausible in relation to odontogenic, cervical, esophageal, or abdominal sources, according to the anatomic pathway. Their detection requires appropriate transport and culture; a routine negative culture after antibiotics does not exclude them. Empirical coverage should reflect this risk without indiscriminately adding every antimicrobial class for all patients. Once the source is identified, therapy can be made more precise and anatomic source control more effective.

Other organisms may produce subacute presentations or manifestations associated with systemic infections. Borrelia, Coxiella, and Brucella are considered in relevant epidemiologic settings, but do not justify universal serologic panels. The distinction between local invasion and an immune response may also remain uncertain. Immunosuppression, neoplasia, diabetes, renal failure, malnutrition, and previous procedures increase the complexity of assessment. In immunosuppressed patients, fungal and mycobacterial hypotheses must also remain open because they require different techniques and treatments.

Pathogenesis and pathophysiology of infectious injury

Entry of the microorganism activates a neutrophilic response and increases permeability of the pericardial microcirculation. Bacteria, inflammatory cells, and debris accumulate in the fluid, while surface injury and fibrin deposition reduce sliding of the pericardial layers. The process may begin with an exudate that is not frankly purulent and later develop overt suppuration. Severity therefore cannot be determined solely from the macroscopic appearance of a single sample, especially after previous antibiotic therapy.

fibrin promotes septa and loculations that divide the cavity into incompletely communicating compartments. A catheter may evacuate the reached portion while leaving other infected pockets. This anatomy explains why the amount drained and cessation of output do not necessarily demonstrate complete control. Subsequent organization involves fibroblasts and extracellular matrix; over time, the problem may shift from a fluid collection to persistent mechanical limitation of filling.

tamponade results from increased external pressure on the cardiac chambers. The rate of accumulation and distribution of fluid matter as much as total volume. A localized postoperative collection may regionally compress a chamber and produce a picture different from a classic circumferential effusion. Elevated intracardiac pressures or pulmonary hypertension may modify echocardiographic findings, whereas hypovolemia may precipitate diastolic collapse. Diagnosis therefore requires a clinical and functional interpretation, not a single measurement.

sepsis adds vasodilation, altered systemic permeability, and possible myocardial depression. The patient may simultaneously have an obstructive component from compression and a distributive component from infection. Hypotension should not be attributed exclusively to one of the two mechanisms because partial treatment may leave a major cause of shock uncorrected. Ventricular function, loading conditions, and response to decompression help identify residual components, together with perfusion, urine output, and lactate trends.

organ dysfunction may result from low cardiac output, venous congestion, the septic response, and treatment toxicity. Kidney and liver function in turn affect pharmacokinetics and antibiotic tolerance, requiring dynamic adjustment of therapy. Elevated troponin may reflect septic injury, supply-demand ischemia, or direct myocardial involvement and does not automatically identify bacterial myocarditis. Interpretation should integrate function, ECG, and context, avoiding substitution of a biomarker for assessment of mechanism.

constriction is a particularly relevant consequence of bacterial infections, especially purulent and tuberculous forms. It may appear during the inflammatory phase or after apparent microbiologic cure. Collagen deposition and adhesions limit expansion, accentuate ventricular interdependence, and cause congestion. An early component may regress with control of the process, whereas established fibrosis may require pericardiectomy. Eradication of bacteria and mechanical recovery of the pericardium are therefore distinct outcomes that must be verified separately.

Clinical presentation, history, and physical examination

The presentation may be dominated by fever and systemic toxicity, rather than by the chest pain typical of idiopathic pericarditis. Chills, tachycardia, marked fatigue, and rapid deterioration may precede recognition of the collection. In older or immunosuppressed patients, fever may be modest or absent; in sedated or ventilated patients, pain cannot be assessed. Absence of the classic clinical triad is not reassuring when infection and instability exist without a complete explanation.

pericarditic pain, when present, may be pleuritic and positional, with an intermittent friction rub. Dyspnea, orthopnea, and a feeling of chest pressure may indicate an increasing effusion, but also pneumonia, empyema, or ventricular dysfunction. The sequence of symptoms relative to the initial source and antibiotics already taken should be reconstructed. Transient improvement followed by recurrent fever may suggest an organized collection or an infection that has not been eradicated, without being specific for any particular organism.

The history should assess procedures and sources: cardiac surgery, vascular access, devices, trauma, skin, odontogenic, or thoracic infections. Previous colonization with resistant organisms and recent hospitalizations are important because they may change initial coverage. Antibiotic history also clarifies the significance of negative cultures. Exposure to tuberculosis or zoonoses is explored when consistent with a subacute course, avoiding conversion of every episode into indiscriminate testing for rare infections.

On physical examination, blood pressure, heart rate, temperature, peripheral perfusion, mental status, and urine output are assessed, together with jugular venous distension and thoracic findings. Muffled heart sounds and pulsus paradoxus may support tamponade, but all should not be awaited before performing echocardiography. Coexisting septic vasodilation may make a classic hemodynamic presentation less apparent. Signs of wound infection, new murmurs, skin lesions, or respiratory asymmetry point toward the source and associated complications.

indolent presentations may manifest with low-grade fever, weight loss, persistent effusion, or progressive congestion. Pericarditis after a procedure should not automatically be attributed to a post-cardiac injury immune-inflammatory syndrome if evidence of infection appears. A response to corticosteroids may attenuate signs without controlling the pathogen. The decision to intensify immunosuppression in an atypical course therefore requires reassessment of infectious suspicion and the quality of available samples.

severity assessment determines the level of care. Sepsis, suspected purulent collection, impaired filling, and organ dysfunction generally require hospital management with rapid access to drainage and intensive support. Current stability does not exclude deterioration over the following hours. Suspicion should be communicated early to cardiology, infectious diseases, and surgery because planning of the procedure and fluid studies may be as decisive as selection of the first antibiotic.

Investigations and demonstration of pericardial infection

urgent echocardiography assesses effusion, distribution, septa, echogenic material, and effects on filling. A complex collection increases suspicion but does not prove pus because fibrin and clots may have overlapping appearances. Chamber collapse, respiratory variation in flows, and venous congestion should be interpreted in the clinical context. A technically limited examination or a localized postoperative collection may require additional windows, transesophageal echocardiography, or CT, provided that further imaging does not delay urgent drainage.

blood cultures are obtained promptly, preferably before antibiotics when this does not cause a dangerous delay. Complete blood count, C-reactive protein, renal and liver function, electrolytes, and lactate help define activity and severity. Procalcitonin may add information but alone neither confirms nor excludes bacterial localization. ECG and troponin complete the cardiac assessment; diffuse ST/PR changes may be absent and troponin requires interpretation of the injury mechanism.

Features supporting the diagnosis of bacterial infection of the pericardium

• Demonstration of bacteria in pericardial fluid or tissue with a clinically reliable microbiologic result.
• Frankly purulent exudate or a suppurative histologic picture, even if cultures are negative after antibiotics.
• Consistency among pericardial findings, systemic infection or a contiguous focus, and results from other samples.
• Reasoned exclusion of contamination, sterile reactive effusion, and other etiologies when the result is not unequivocal.

These elements describe a diagnostic reasoning process, not a validated score. When suppuration is suspected, pericardiocentesis or surgical drainage also has a diagnostic purpose and does not require tamponade to already be present. Fluid is sent for Gram stain, aerobic and anaerobic cultures, and susceptibility testing, with further investigations added according to risk. Sample quality matters: material obtained directly from the cavity differs from a sample collected later from a potentially colonized drainage system.

The fluid profile may show neutrophil predominance, low glucose, and high inflammatory activity, but no isolated biochemical value identifies the bacterium. A low pericardial-to-serum glucose ratio is consistent with local consumption without being specific. A lymphocytic exudate points in a different direction but does not exclude every infection, depending on phase and treatment. A negative direct stain does not eliminate suspicion; culture and molecular method sensitivity is influenced by bacterial burden, antibiotics, and pathogen characteristics.

molecular techniques, including broad-range bacterial testing on appropriate material, may help in selected culture-negative cases. They do not always replace isolation because genetic identification may not provide a complete susceptibility profile and may be affected by contamination. The laboratory should know if slow-growing organisms, anaerobes, or mycobacteria are suspected before the procedure is set up. The most robust diagnosis arises from concordance among anatomy, clinical findings, and microbiology, not from isolated positivity on a panel.

Search for the source, extent, and differential diagnosis

Once infection is recognized, the source must be defined. Chest CT may show empyema, complicated pneumonia, mediastinitis, postoperative collections, or pathologic relationships with the esophagus and adjacent structures. Contrast selection takes renal function and urgency into account, but contrast risk should not be considered separately from the benefit of identifying a correctable source. In an unstable patient, echocardiography and immediate pericardial control may precede complete anatomic assessment.

persistent bacteremia requires investigation for endocarditis, device infection, septic thrombophlebitis, and metastatic foci according to the organism and presentation. Transesophageal echocardiography and other investigations are selected for the clinical question, without simply repeating assessment of the collection. Persistently positive blood cultures after starting an active antibiotic may indicate inadequate source control, unrecognized resistance, or insufficient drug exposure. These possibilities should be addressed before attributing fever to a residual inflammatory response alone.

Distinction from a reactive effusion is important in thoracic infections. Not every effusion during pneumonia contains bacteria; a small sterile effusion may accompany the systemic response. The probability of invasion increases with a complex collection, pericardial signs, persistent sepsis, and unexplained deterioration. Sampling is decided by balancing benefits and risks, but suspected pus requires a more active approach. A negative culture after antibiotics alone does not permit reclassification of a macroscopically suppurative collection as sterile.

tuberculosis enters the differential diagnosis especially in subacute presentations, relevant exposures, and immunosuppression. It requires dedicated cultures and tests that are not automatically included in routine bacterial cultures. Fungi, neoplasms, and immune-mediated diseases may produce complex effusions and should be investigated when the phenotype requires it. Cytology may be useful if there is a concomitant oncologic suspicion. The possibility of simultaneous processes is particularly relevant in frail patients or those already receiving multiple therapies.

subsequent hemodynamic assessment verifies what remains after drainage. Persistent elevated venous pressure, edema, and constrictive Doppler signs may indicate effusive-constrictive physiology, but residual fluid, right-sided dysfunction, and severe tricuspid regurgitation should be excluded. Magnetic resonance imaging may characterize inflammation and tissue when the patient is stable; it is not the priority examination during shock or when a collection needs evacuation. Catheterization is reserved for uncertainties that would change strategy.

multidisciplinary assessment integrates microbiology, anatomy, and therapeutic options. It is useful to define who manages the drain, when to repeat imaging and blood cultures, and which findings mandate surgery. Laboratory results should be reinterpreted in light of the source and procedure, especially for skin organisms or samples obtained after prolonged catheter dwell time. Incomplete diagnosis of the source may make a formally correct antibiotic regimen ineffective and promote reaccumulation, infectious relapse, and permanent pericardial injury.

Antimicrobial treatment and source control

Treatment of clinically significant pyogenic forms requires prompt intravenous antibiotics and immediate assessment of the need for drainage. In probable or confirmed sepsis, especially with shock, therapy should not await culture results. Samples are collected rapidly when possible. Initial coverage should be broad enough for plausible pathogens, but constructed according to community- or healthcare-associated origin, exposures, previous isolates, immune status, and the local antibiogram, avoiding a fixed regimen applied to every setting.

empirical coverage generally includes staphylococci and streptococci; the need to cover methicillin-resistant Staphylococcus aureus and Gram-negative bacilli depends on individual risk. An agent active against resistant staphylococci, such as vancomycin when appropriate, may be combined with a beta-lactam selected according to source and expected resistance. Appropriately broad cephalosporins, piperacillin-tazobactam, or carbapenems address different scenarios and are not interchangeable equivalents. Anaerobic coverage is particularly justified by esophageal, cervical, or abdominal sources; selection requires infectious-disease expertise.

targeted therapy is adapted to organism identification and susceptibility. Isolation of a methicillin-susceptible staphylococcus may allow transition to an appropriate antistaphylococcal beta-lactam; other organisms require specific regimens. Dose, interval, and infusion method should ensure adequate exposure in sepsis, taking renal function, weight, volume of distribution, and extracorporeal support into account. Therapeutic drug monitoring is used when indicated. De-escalation reduces toxicity and selective pressure without compromising infection control.

duration depends on the organism, source, completeness of drainage, bacteremia, and complications. For purulent pericarditis, the 2025 ESC guidelines indicate a minimum duration of three weeks, to be extended according to clinical resolution and context; this is not an automatic stopping point. Endocarditis, osteomyelitis, or residual collections may require longer courses. Reduction in fever or C-reactive protein is insufficient if a source persists. Any transition to oral therapy requires stability, an appropriate drug, and a verifiable specialist plan.

drainage is essential in tamponade and suspected suppuration. Image-guided pericardiocentesis may achieve decompression and obtain samples, but thick pus, loculations, and postoperative collections may require surgical access, lavage, and removal of adhesions that prevent evacuation. The choice depends not only on effusion size, but on the ability to control the entire infected compartment. A catheter with no further output should be assessed for obstruction or isolation within a pocket, not automatically considered proof of cure.

intrapericardial fibrinolysis may be considered in loculated purulent collections to facilitate drainage, as contemplated by contemporary recommendations. Evidence includes heterogeneous studies and series; it does not define a single universal regimen or eliminate bleeding risk. The approach requires assessment of contraindications, a functioning access, and the ability to proceed to surgery if ineffective. It should not delay surgery in uncontrolled sepsis, unfavorable anatomy, or persistent infected material that cannot be evacuated.

hemodynamic support treats the septic component while obstruction is corrected. Crystalloids and vasopressors are titrated to perfusion with frequent reassessment; norepinephrine is the standard initial vasopressor in ordinary septic shock. In tamponade, fluids or vasopressors may provide temporary support but do not replace drainage. Anti-inflammatory drugs, colchicine, and corticosteroids do not eradicate infection and are not the primary treatment. Any corticosteroids used for refractory shock respond to a distinct intensive-care indication rather than immunosuppression of pericarditis.

Prognosis, complications, and follow-up

prognosis depends on prompt recognition, adequacy of source control, and host conditions. Historical series report high mortality, but percentages from different eras and populations cannot be directly transferred to a contemporary patient. Delayed diagnosis, shock, multiple collections, and comorbidities increase risk. Availability of active antibiotics does not eliminate the need for timely intervention when the pericardium contains infected material.

Immediate complications include tamponade and shock, myocardial dysfunction, arrhythmias, and multiorgan failure. After decompression, the response must be assessed: persistently low blood pressure may result from sepsis, myocardial injury, or residual collection. Sudden deterioration requires consideration of procedural complications, bleeding, and respiratory problems. Clinical assessment should be accompanied by imaging directed to the question, without assuming that a technically successful procedure has resolved every component of the disease.

persistent infection may manifest with fever, bacteremia, prolonged purulent output, or reaccumulation. Before automatically broadening antibiotics, drainage, an extracardiac source, and reliability of susceptibility testing should be checked. Growth of a new organism from a catheter may represent superinfection or colonization and requires correlation. Distinguishing microbiologic failure from inadequate anatomic source control guides treatment and prevents ineffective prolonged courses.

postinfectious constriction requires surveillance even after fever and cultures have normalized. Exertional dyspnea, edema, ascites, and persistent jugular venous distension require assessment of filling. Early physiology may have a reversible inflammatory component, but refractory congestion and persistent fibrosis require evaluation for pericardiectomy. Surgical indication considers infectious activity, nutritional status, organ function, and operative risk; it does not derive from thickening alone or isolated calcification.

treatment consequences include renal and hepatic injury, cytopenias, allergic reactions, and vascular-access complications. Monitoring is adapted to the drugs and duration, with particular attention after discharge. Reduced renal function may reflect sepsis, congestion, or toxicity and requires causal interpretation. An outpatient antimicrobial therapy program is appropriate only when stability, source control, and monitoring capability permit it.

follow-up verifies infectious cure, hemodynamic recovery, and independence. Drain removal should consider output trends and imaging, whereas completion of antibiotics requires an assessment of the entire episode. Patients should know the signs of recurrent congestion or infection and have a defined route to reassessment. Prevention mainly concerns source control, proper device management, and timely treatment of related infections; there is no universally indicated chronic antibiotic prophylaxis after cured bacterial pericarditis.

References
1. Schulz-Menger J et al. 2025 ESC Guidelines for the management of myocarditis and pericarditis. European Heart Journal. 2025;46(40):3952-4041.
2. Klein AL et al. Pericardial Diseases: International Position Statement on New Concepts and Advances in Multimodality Cardiac Imaging. JACC: Cardiovascular Imaging. 2024;17(8):937-988.
3. Adler Y et al. 2015 ESC Guidelines for the diagnosis and management of pericardial diseases: The Task Force for the Diagnosis and Management of Pericardial Diseases of the European Society of Cardiology (ESC). Endorsed by: The European Association for Cardio-Thoracic Surgery (EACTS). European Heart Journal. 2015;36(42):2921-2964.
4. Pankuweit S et al. Bacterial pericarditis: diagnosis and management. American Journal of Cardiovascular Drugs. 2005;5(2):103-112.
5. Sagristà-Sauleda J et al. Purulent pericarditis: review of a 20-year experience in a general hospital. Journal of the American College of Cardiology. 1993;22(6):1661-1665.
6. Roberts WC. Pericardial heart disease: its morphologic features and its causes. Proceedings (Baylor University Medical Center). 2005;18(1):38-55.
7. Spodick DH. Acute cardiac tamponade. New England Journal of Medicine. 2003;349(7):684-690.
8. Imazio M et al. Risk of constrictive pericarditis after acute pericarditis. Circulation. 2011;124(11):1270-1275.
9. Augustin P et al. Clinical review: intrapericardial fibrinolysis in management of purulent pericarditis. Critical Care. 2011;15(2):220.
10. Wiyeh AB et al. A systematic review of the efficacy and safety of intrapericardial fibrinolysis in patients with pericardial effusion. International Journal of Cardiology. 2018;250:223-228.
11. Society of Critical Care Medicine; European Society of Intensive Care Medicine. Surviving Sepsis Campaign: International Guidelines for Management of Sepsis and Septic Shock 2026. Society of Critical Care Medicine. 2026. Online recommendations. Accessed September 26, 2026. https://www.sccm.org/clinical-resources/guidelines/guidelines/surviving-sepsis-campaign-international-guidelines-for-management-of-sepsis-and-septic-shock-2026.
12. Sagristà-Sauleda J et al. Effusive-constrictive pericarditis. New England Journal of Medicine. 2004;350(5):469-475.
13. Mayosi BM et al. Tuberculous pericarditis. Circulation. 2005;112(23):3608-3616.