High-dose antibiotics are administered by the intravenous route to maximize diffusion of antibiotic molecules into vegetation(s) from the blood filling the chambers of the heart. This is necessary because neither the heart valves nor the vegetations adherent to them are supplied by blood vessels. Antibiotics are typically continued for two to six weeks depending on the characteristics of the infection and the causative microorganisms.

In acute endocarditis, due to the fulminant inflammation empirical antibiotic therapy is started immediately after the blood has been drawn for culture. This usually includes vancomycin and ceftriaxone IV infusions until the microbial identification and susceptibility report with the minimum inhibitory concentration becomes available allowing for modification of the antimicrobial therapy to target the specific microorganism. It should be noted that the routine use of gentamicin to treat endocarditis has fallen out of favor due to the lack of evidence to support its use (except in infections caused by "Enterococcus" and nutritionally variant "streptococci") and the high rate of complications.

In subacute endocarditis, where patient's hemodynamic status is usually stable, antibiotic treatment can be delayed till the causative microorganism can be identified.

The most common organism responsible for infective endocarditis is "Staphylococcus aureus", which is resistant to penicillin in most cases. High rates of resistance to oxacillin are also seen, in which cases treatment with vancomycin is required.

Viridans group "streptococci" and "Streptococcus bovis" are usually highly susceptible to penicillin and can be treated with penicillin or ceftriaxone.

Relatively resistant strains of viridans group "streptococci" and "Streptococcus bovis" are treated with penicillin or ceftriaxone along with a shorter 2 week course of an aminoglycoside during the initial phase of treatment.

Highly penicillin resistant strains of viridans group "streptococci", nutritionally variant "streptococci" like "Granulicatella sp.", "Gemella sp." and "Abiotrophia defectiva", and "Enterococci" are usually treated with a combination therapy consisting of penicillin and an aminoglycoside for the entire duration of 4–6 weeks.

Selected patients may be treated with a relatively shorter course of treatment (2 weeks) with benzyl penicillin IV if infection is caused by viridans group "streptococci" or "Streptococcus bovis" as long as the following conditions are met:

- Endocarditis of a native valve, not of a prosthetic valve

- An MIC ≤ 0.12 mg/l

- Complication such as heart failure, arrhythmia, and pulmonary embolism occur

- No evidence of extracardiac complication like septic thromboembolism

- No vegetations > 5mm in diameter conduction defects

- Rapid clinical response and clearance of blood stream infection

Additionally oxacillin susceptible "Staphylococcus aureus" native valve endocarditis of the right side can also be treated with a short 2 week course of a beta-lactam antibiotic like nafcillin with or without aminoglycosides.

Surgical debridement of infected material and replacement of the valve with a mechanical or bioprosthetic artificial heart valve is necessary in certain situations:

- Patients with significant valve stenosis or regurgitation causing heart failure

- Evidence of hemodynamic compromise in the form of elevated end-diastolic left ventricular or left atrial pressure or moderate to severe pulmonary hypertension

- Presence of intracardiac complications like paravalvular abscess, conduction defects or destructive penetrating lesions

- Recurrent septic emboli despite appropriate antibiotic treatment

- Large vegetations (> 10 mm)

- Persistently positive blood cultures despite appropriate antibiotic treatment

- Prosthetic valve dehiscence

- Relapsing infection in the presence of a prosthetic valve

- Abscess formation

- Early closure of mitral valve

- Infection caused by fungi or resistant Gram negative bacteria.

The guidelines were recently updated by both the American College of Cardiology and the European Society of Cardiology. There was a recent meta-analysis published that showed surgical intervention at 7 days or less is associated with lower mortality .

Infective endocarditis is associated with 18% in-hospital mortality.

Another form of endocarditis is healthcare-associated endocarditis when the infecting organism is believed to be transmitted in a health care setting like hospital, dialysis unit or a residential nursing home. Nosocomial endocarditis is a form of healthcare associated endocarditis in which the infective organism is acquired during stay in a hospital and it is usually secondary to presence of intravenous catheters, total parenteral nutrition lines, pacemakers, etc.

When properly diagnosed, the mortality of Lemierre's syndrome is about 4.6%. Since this disease is not well known and often remains undiagnosed, mortality might be much higher.

Lemierre's syndrome is primarily treated with antibiotics given intravenously. "Fusobacterium necrophorum" is generally highly susceptible to beta-lactam antibiotics, metronidazole, clindamycin and third generation cephalosporins while the other fusobacteria have varying degrees of resistance to beta-lactams and clindamycin. Additionally, there may exist a co-infection by another bacterium. For these reasons is often advised not to use monotherapy in treating Lemierre's syndrome. Penicillin and penicillin-derived antibiotics can thus be combined with a beta-lactamase inhibitor such as clavulanic acid or with metronidazole. Clindamycin can be given as monotherapy.

If antibiotic therapy does not improve the clinical picture, it may prove useful to drain any abscesses and/or perform ligation of the internal jugular vein where the antibiotic can not penetrate.

There is no evidence to opt for or against the use of anticoagulation therapy. The low incidence of Lemierre's syndrome has not made it possible to set up clinical trials to study the disease.

The disease can often be untreatable, especially if other negative factors occur, i.e. various diseases occurring at the same time, such as meningitis, pneumonia.

Tuberculous pericarditis is a form of pericarditis.

Pericarditis caused by tuberculosis is difficult to diagnose, because definitive diagnosis requires culturing "Mycobacterium tuberculosis" from aspirated pericardial fluid or pericardial , which requires high technical skill and is often not diagnostic (the yield from culture is low even with optimum specimens). The Tygerberg scoring system helps the clinician to decide whether pericarditis is due to tuberculosis or whether it is due to another cause: night sweats (1 point), weight loss (1 point), fever (2 point), serum globulin > 40g/l (3 points), blood total leucocyte count <10 x 10/l (3 points); a total score of 6 or more is highly suggestive of tuberculous pericarditis. Pericardial fluid with an interferon-γ level greater than 50/ml is highly specific for tuberculous pericarditis.

There are no randomized trials which evaluate the length of anti-tuberculosis treatment required for tuberculous pericarditis. There is a small but not conclusive benefit for treatment with a schedule of steroids with anti-tuberculosis drugs. Open surgical drainage of fluid though effective in preventing cardiac tamponade was associated with more deaths.

In the majority of immunocompetent individuals, histoplasmosis resolves without any treatment. Antifungal medications are used to treat severe cases of acute histoplasmosis and all cases of chronic and disseminated disease. Typical treatment of severe disease first involves treatment with amphotericin B, followed by oral itraconazole.

Liposomal preparations of amphotericin B are more effective than deoxycholate preparations. The liposomal preparation is preferred in patients that might be at risk of nephrotoxicity, although all preparations of amphotericin B have risk of nephrotoxicity. Individuals taking amphotericin B are monitored for renal function.

Treatment with itraconazole will need to continue for at least a year in severe cases, while in acute pulmonary histoplasmosis, 6 to 12 weeks treatment is sufficient. Alternatives to itraconazole are posaconazole, voriconazole, and fluconazole. Individuals taking itraconazole are monitored for hepatic function.

Prognosis depends on the pathogen responsible for the infection and risk group. Overall mortality for "Candida" meningitis is 10-20%, 31% for patients with HIV, and 11% in neurosurgical cases (when treated). Prognosis for "Aspergillus" and coccidioidal infections is poor.

It is not practical to test or decontaminate most sites that may be contaminated with "H. capsulatum", but the following sources list environments where histoplasmosis is common, and precautions to reduce a person's risk of exposure, in the three parts of the world where the disease is prevalent. Precautions common to all geographical locations would be to avoid accumulations of bird or bat droppings.

The US National Institute for Occupational Safety and Health (NIOSH) provides information on work practices and personal protective equipment that may reduce the risk of infection. This document is available in English and Spanish.

Authors at the University of Nigeria have published a review which includes information on locations in which histoplasmosis has been found in Africa (in chicken runs, bats and the caves bats infest, and in soil), and a thorough reference list including English, French, and Spanish language references.

About 30% of people with viral pericarditis or pericarditis of an unknown cause have one or several recurrent episodes.

The treatment in viral or idiopathic pericarditis is with aspirin, or non-steroidal anti-inflammatory drugs (NSAIDs such as ibuprofen). Colchicine may be added to the above as it decreases the risk of further episodes of pericarditis.

Severe cases may require one or more of the following:

- pericardiocentesis to treat pericardial effusion/tamponade

- antibiotics to treat tuberculosis or other bacterial causes.

- steroids are used in acute pericarditis but are not favored because they increase the chance of recurrent pericarditis.

- in rare cases, surgery

- in cases of constrictive pericarditis, pericardiectomy

In immunocompromised patients, prophylaxis with co-trimoxazole (trimethoprim/sulfamethoxazole), atovaquone, or regular pentamidine inhalations may help prevent PCP.

Antipneumocystic medication is used with concomitant steroids in order to avoid inflammation, which causes an exacerbation of symptoms about four days after treatment begins if steroids are not used. By far the most commonly used medication is trimethoprim/sulfamethoxazole, but some patients are unable to tolerate this treatment due to allergies. Other medications that are used, alone or in combination, include pentamidine, trimetrexate, dapsone, atovaquone, primaquine, pafuramidine maleate (under investigation), and clindamycin. Treatment is usually for a period of about 21 days.

Pentamidine is less often used as its major limitation is the high frequency of side effects. These include acute pancreatic inflammation, kidney failure, liver toxicity, decreased white blood cell count, rash, fever, and low blood sugar.

Patients with uncomplicated acute pericarditis can generally be treated and followed up in an outpatient clinic. However, those with high risk factors for developing complications (see above) will need to be admitted to an inpatient service, most likely an ICU setting. High risk patients include the following:

- subacute onset

- high fever (> 100.4 F/38 C) and leukocytosis

- development of cardiac tamponade

- large pericardial effusion (echo-free space > 20 mm) resistant to NSAID treatment

- immunocompromised

- history of oral anticoagulation therapy

- acute trauma

- failure to respond to seven days of NSAID treatment

Pericardiocentesis is a procedure whereby the fluid in a pericardial effusion is removed through a needle. It is performed under the following conditions:

- presence of moderate or severe cardiac tamponade

- diagnostic purpose for suspected purulent, tuberculosis, or neoplastic pericarditis

- persistent symptomatic pericardial effusion

NSAIDs in "viral" or "idiopathic" pericarditis. In patients with underlying causes other than viral, the specific etiology should be treated. With idiopathic or viral pericarditis, NSAID is the mainstay treatment. Goal of therapy is to reduce pain and inflammation. The course of the disease may not be affected. The preferred NSAID is ibuprofen because of rare side effects, better effect on coronary flow, and larger dose range. Depending on severity, dosing is between 300–800 mg every 6–8 hours for days or weeks as needed. An alternative protocol is aspirin 800 mg every 6–8 hours. Dose tapering of NSAIDs may be needed. In pericarditis following acute myocardial infarction, NSAIDs other than aspirin should be avoided since they can impair scar formation. As with all NSAID use, GI protection should be engaged. Failure to respond to NSAIDs within one week (indicated by persistence of fever, worsening of condition, new pericardial effusion, or continuing chest pain) likely indicates that a cause other than viral or idiopathic is in process.

Colchicine, which has been essential to treat recurrent pericarditis, has been supported for routine use in acute pericarditis by recent prospective studies. Colchicine can be given 0.6 mg twice a day (0.6 mg daily for patients <70 kg) for 3 months following an acute attack. It should be considered in all patients with acute pericarditis, preferably in combination with a short-course of NSAIDs. For patients with a first episode of acute idiopathic or viral pericarditis, they should be treated with an NSAID plus colchicine 1–2 mg on first day followed by 0.5 daily or twice daily for three months. It should be avoided or used with caution in patients with severe renal insufficiency, hepatobiliary dysfunction, blood dyscrasias, and gastrointestinal motility disorders.

Corticosteroids are usually used in those cases that are clearly refractory to NSAIDs and colchicine and a specific cause has not been found. Systemic corticosteroids are usually reserved for those with autoimmune disease.

Uremic pericarditis is a form of pericarditis. It causes fibrinous pericarditis. The main cause of the disease is poorly understood.

Since the start of the AIDS epidemic, PCP has been closely associated with AIDS. Because it only occurs in an immunocompromised host, it may be the first clue to a new AIDS diagnosis if the patient has no other reason to be immunocompromised (e.g. taking immunosuppressive drugs for organ transplant). An unusual rise in the number of PCP cases in North America, noticed when physicians began requesting large quantities of the rarely used antibiotic pentamidine, was the first clue to the existence of AIDS in the early 1980s.

Prior to the development of more effective treatments, PCP was a common and rapid cause of death in persons living with AIDS. Much of the incidence of PCP has been reduced by instituting a standard practice of using oral co-trimoxazole (Bactrim / Septra) to prevent the disease in people with CD4 counts less than 200/μL. In populations that do not have access to preventive treatment, PCP continues to be a major cause of death in AIDS.

The definitive treatment for constrictive pericarditis is pericardial stripping, which is a surgical procedure where the entire pericardium is peeled away from the heart. This procedure has significant risk involved, with mortality rates of 6% or higher in major referral centers.

A poor outcome is almost always the result after a pericardiectomy is performed for constrictive pericarditis whose origin was radiation-induced, further some patients may develop heart failure post-operatively.

Fungal meningitis is treated with long courses of high dose antifungal medications. The duration of treatment is dependent upon the causal pathogen and the patient's ability to stave off the infection; for patients with a weaker immune system or diabetes, treatment will often take longer.

One of the most feared complications of acute pericarditis is cardiac tamponade. Cardiac tamponade is accumulation of enough fluid in the pericardial space --- pericardial effusion --- to cause serious obstruction to the inflow of blood to the heart. Signs of cardiac tamponade include distended neck veins, muffled heart sounds when listening with a stethoscope, and low blood pressure (together known as Beck's triad). This condition can be fatal if not immediately treated.

Another longer term complication of pericarditis, if it recurs over a longer period of time (normally more than 3 months), is progression to constrictive pericarditis. Recent studies have shown this to be an uncommon complication. The definitive treatment for constrictive pericarditis is pericardial stripping, which is a surgical procedure where the entire pericardium is peeled away from the heart.

Opportunistic infections caused by Feline Leukemia Virus and Feline immunodeficiency virus retroviral infections can be treated with Lymphocyte T-Cell Immune Modulator.

Individuals at higher risk are often prescribed prophylactic medication to prevent an infection from occurring. A patient's risk level for developing an opportunistic infection is approximated using the patient's CD4 T-cell count and sometimes other markers of susceptibility. Common prophylaxis treatments include the following:

The cause of constrictive pericarditis in the developing world are idiopathic in origin, though likely infectious in nature. In regions where tuberculosis is common, it is the cause in a large portion of cases.

Causes of constrictive pericarditis include:

- Tuberculosis

- Incomplete drainage of purulent pericarditis

- Fungal and parasitic infections

- Chronic pericarditis

- Postviral pericarditis

- Postsurgical

- Following MI, post-myocardial infarction

- In association with pulmonary asbestos

Antibiotics improve outcomes in those with bacterial pneumonia. Antibiotic choice depends initially on the characteristics of the person affected, such as age, underlying health, and the location the infection was acquired. In the UK, treatment before culture results with amoxicillin is recommended as the first line for community-acquired pneumonia, with doxycycline or clarithromycin as alternatives. In North America, where the "atypical" forms of community-acquired pneumonia are more common, macrolides (such as azithromycin or erythromycin), and doxycycline have displaced amoxicillin as first-line outpatient treatment in adults. In children with mild or moderate symptoms, amoxicillin remains the first line. The use of fluoroquinolones in uncomplicated cases is discouraged due to concerns about side-effects and generating resistance in light of there being no greater clinical benefit.

For those who require hospitalization and caught their pneumonia in the community the use of a β-lactam such as cephazolin plus macrolide such as azithromycin or a fluoroquinolones is recommended. The addition of corticosteroids also appears to improve outcomes.

The duration of treatment has traditionally been seven to ten days, but increasing evidence suggests that shorter courses (three to five days) are similarly effective. Recommendations for hospital-acquired pneumonia include third- and fourth-generation cephalosporins, carbapenems, fluoroquinolones, aminoglycosides, and vancomycin. These antibiotics are often given intravenously and used in combination. In those treated in hospital, more than 90% improve with the initial antibiotics.

Uremic pericarditis is correlated to the degree of azotemia in the system. BUN is normally >60 mg/dL (normal is 7–20 mg/dL). The pathogenesis is poorly understood.

Oral antibiotics, rest, simple analgesics, and fluids usually suffice for complete resolution. However, those with other medical conditions, the elderly, or those with significant trouble breathing may require more advanced care. If the symptoms worsen, the pneumonia does not improve with home treatment, or complications occur, hospitalization may be required. Worldwide, approximately 7–13% of cases in children result in hospitalization, whereas in the developed world between 22 and 42% of adults with community-acquired pneumonia are admitted. The CURB-65 score is useful for determining the need for admission in adults. If the score is 0 or 1, people can typically be managed at home; if it is 2, a short hospital stay or close follow-up is needed; if it is 3–5, hospitalization is recommended. In children those with respiratory distress or oxygen saturations of less than 90% should be hospitalized. The utility of chest physiotherapy in pneumonia has not yet been determined. Non-invasive ventilation may be beneficial in those admitted to the intensive care unit. Over-the-counter cough medicine has not been found to be effective nor has the use of zinc in children. There is insufficient evidence for mucolytics.

Intensive cardiac care and immunosuppressives including corticosteroids are helpful in the acute stage of the disease. Chronic phase has, mainly debility control and supportive care options.

The treatment of choice is penicillin, and the duration of treatment is around 10 days. Antibiotic therapy (using injected penicillin) has been shown to reduce the risk of acute rheumatic fever. In individuals with a penicillin allergy, erythromycin, other macrolides, and cephalosporins have been shown to be effective treatments.

Treatment with ampicillin/sulbactam, amoxicillin/clavulanic acid, or clindamycin is appropriate if deep oropharyngeal abscesses are present, in conjunction with aspiration or drainage. In cases of streptococcal toxic shock syndrome, treatment consists of penicillin and clindamycin, given with intravenous immunoglobulin.

For toxic shock syndrome and necrotizing fasciitis, high-dose penicillin and clindamycin are used. Additionally, for necrotizing fasciitis, surgery is often needed to remove damaged tissue and stop the spread of the infection.

No instance of penicillin resistance has been reported to date, although since 1985, many reports of penicillin tolerance have been made. The reason for the failure of penicillin to treat "S. pyogenes" is most commonly patient noncompliance, but in cases where patients have been compliant with their antibiotic regimen, and treatment failure still occurs, another course of antibiotic treatment with cephalosporins is common.