Although the risk of Legionnaires' disease being spread by large-scale water systems cannot be eliminated, it can be greatly reduced by writing and enforcing a highly detailed, systematic water safety plan appropriate for the specific type of facility involved (office building, hospital, hotel, spa, cruise ship, etc.) Some of the elements that such a plan may include are the following:

- Keeping water temperature either above or below the range in which the "Legionella" bacterium thrives.

- Preventing stagnation, for example by removing from a network of pipes any sections that have no outlet (dead ends). Where stagnation is unavoidable, for example when a wing of a hotel is closed for the off-season, systems must be thoroughly disinfected just prior to resuming normal operation.

- Preventing the buildup of biofilm, for example by not using (or by replacing) construction materials that encourage its development, and by reducing the quantity of nutrients for bacterial growth that enter the system.

- Periodic disinfection of the system, by high heat or a chemical biocide, and the use of chlorination where appropriate.

- System design (or renovation) that reduces the production of aerosols and reduces human exposure to them, for example by directing them well away from building air intakes.

An effective water safety plan will also cover such matters as training, record-keeping, communication among staff, contingency plans and management responsibilities. The format and content of the plan may be prescribed by public health laws or regulations. There is tentative evidence for the treatment of the water with copper-silver ionization or ultraviolet light.

Effective antibiotics include most macrolides, tetracyclines, ketolides, and quinolones. "Legionella" multiply within the cell, so any effective treatment must have excellent intracellular penetration. Current treatments of choice are the respiratory tract quinolones (levofloxacin, moxifloxacin, gemifloxacin) or newer macrolides (azithromycin, clarithromycin, roxithromycin). The antibiotics used most frequently have been levofloxacin, doxycycline, and azithromycin.

Macrolides (azithromycin) are used in all age groups, while tetracyclines (doxycycline) are prescribed for children above the age of 12 and quinolones (levofloxacin) above the age of 18. Rifampicin can be used in combination with a quinolone or macrolide. It is uncertain whether rifampicin is an effective antibiotic to take for treatment. The Infectious Diseases Society of America does not recommend the use of rifampicin with added regimens. Tetracyclines and erythromycin led to improved outcomes compared to other antibiotics in the original American Legion outbreak. These antibiotics are effective because they have excellent intracellular penetration in "Legionella"-infected cells. The recommended treatment is 5–10 days of levofloxacin or 3–5 days of azithromycin, but in people who are immunocompromised, have severe disease, or other pre-existing health conditions, longer antibiotic use may be necessary. During outbreaks, prophylactic antibiotics have been successfully used to prevent Legionnaires' disease in high-risk individuals who have possibly been exposed.

The mortality at the original American Legion convention in 1976 was high (29 deaths in 182 infected individuals) because the antibiotics used (including penicillins, cephalosporins, and aminoglycosides) had poor intracellular penetration. Mortality has plunged to less than 5% if therapy is started quickly. Delay in giving the appropriate antibiotic leads to higher mortality.

Neuraminidase inhibitors may be used to treat viral pneumonia caused by influenza viruses (influenza A and influenza B). No specific antiviral medications are recommended for other types of community acquired viral pneumonias including SARS coronavirus, adenovirus, hantavirus, and parainfluenza virus. Influenza A may be treated with rimantadine or amantadine, while influenza A or B may be treated with oseltamivir, zanamivir or peramivir. These are of most benefit if they are started within 48 hours of the onset of symptoms. Many strains of H5N1 influenza A, also known as avian influenza or "bird flu", have shown resistance to rimantadine and amantadine. The use of antibiotics in viral pneumonia is recommended by some experts, as it is impossible to rule out a complicating bacterial infection. The British Thoracic Society recommends that antibiotics be withheld in those with mild disease. The use of corticosteroids is controversial.

"Streptococcus pneumoniae" — amoxicillin (or erythromycin in patients allergic to penicillin); cefuroxime and erythromycin in severe cases.

"Staphylococcus aureus" — flucloxacillin (to counteract the organism's β-lactamase).

People who have difficulty breathing due to pneumonia may require extra oxygen. An extremely sick individual may require artificial ventilation and intensive care as life-saving measures while his or her immune system fights off the infectious cause with the help of antibiotics and other drugs.

The most high-profile death caused by parrot fever is that of Thea Selway, mother of Radiohead drummer and singer Philip Selway.

Pontiac fever does not spread from person to person. It is acquired through aersolization of water droplets and/or potting soil containing "Legionella" bacteria.

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.

Sources of the causative agents are aquatic systems and potting soil. The first outbreak caused by inhalation of aersolized potting soil was discovered in New Zealand in January 2007. A total of 10 workers at a nursery came down with Pontiac fever. It was the first identification of "L. longbeachae".

CAP may be prevented by treating underlying illnesses increasing its risk, by smoking cessation and vaccination of children and adults. Vaccination against "haemophilus influenzae" and "streptococcus pneumoniae" in the first year of life has reduced their role in childhood CAP. A vaccine against "streptococcus pneumoniae", available for adults, is recommended for healthy individuals over 65 and all adults with COPD, heart failure, diabetes mellitus, cirrhosis, alcoholism, cerebrospinal fluid leaks or who have had a splenectomy. Re-vaccination may be required after five or ten years.

Patients who are vaccinated against "streptococcus pneumoniae", health professionals, nursing-home residents and pregnant women should be vaccinated annually against influenza. During an outbreak, drugs such as amantadine, rimantadine, zanamivir and oseltamivir have been demonstrated to prevent influenza.

Patients with HCAP are more likely than those with community-acquired pneumonia to receive inappropriate antibiotics that do not target the bacteria causing their disease.

In 2002, an expert panel made recommendations about the evaluation and treatment of probable nursing home-acquired pneumonia. They defined probably pneumonia, emphasized expedite antibiotic treatment (which is known to improve survival) and drafted criteria for the hospitalization of willing patients.

For initial treatment in the nursing home, a fluoroquinolone antibiotic suitable for respiratory infections (moxifloxacin, for example), or amoxicillin with clavulanic acid plus a macrolide has been suggested. In a hospital setting, injected (parenteral) fluoroquinolones or a second- or third-generation cephalosporin plus a macrolide could be used. Other factors that need to be taken into account are recent antibiotic therapy (because of possible resistance caused by recent exposure), known carrier state or risk factors for resistant organisms (for example, known carrier of MRSA or presence of bronchiectasis predisposing to Pseudomonas aeruginosa), or suspicion of possible Legionella pneumophila infection (legionnaires disease).

In 2005, the American Thoracic Society and Infectious Diseases Society of America have published guidelines suggesting antibiotics specifically for HCAP. The guidelines recommend combination therapy with an agent from each of the following groups to cover for both "Pseudomonas aeruginosa" and MRSA. This is based on studies using sputum samples and intensive care patients, in whom these bacteria were commonly found.

- cefepime, ceftazidime, imipenem, meropenem or piperacillin–tazobactam; plus

- ciprofloxacin, levofloxacin, amikacin, gentamicin, or tobramycin; plus

- linezolid or vancomycin

In one observational study, empirical antibiotic treatment that was not according to international treatment guidelines was an independent predictor of worse outcome among HCAP patients.

Guidelines from Canada suggest that HCAP can be treated like community-acquired pneumonia with antibiotics targeting Streptococcus pneumoniae, based on studies using blood cultures in different settings which have not found high rates of MRSA or Pseudomonas.

Besides prompt antibiotic treatment, supportive measure for organ failure (such as cardiac decompensation) are also important. Another consideration goes to hospital referral; although more severe pneumonia requires admission to an acute care facility, this also predisposes to hazards of hospitalization such as delirium, urinary incontinence, depression, falls, restraint use, functional decline, adverse drug effects and hospital infections. Therefore, mild pneumonia might be better dealt with inside the long term care facility. In patients with a limited life expectancy (for example, those with advanced dementia), end-of-life pneumonia also requires recognition and appropriate, palliative care.

Psittacosis was one of more than a dozen agents that the United States researched as potential biological weapons before the nation suspended its biological weapons program.

Most newborn infants with CAP are hospitalized, receiving IV ampicillin and gentamicin for at least ten days to treat the common causative agents "streptococcus agalactiae", "listeria monocytogenes" and "escherichia coli". To treat the herpes simplex virus, IV acyclovir is administered for 21 days.

Postinfection treatment involves a combination of antituberculosis antibiotics, including rifampicin, rifabutin, ciprofloxacin, amikacin, ethambutol, streptomycin, clarithromycin or azithromycin.

NTM infections are usually treated with a three-drug regimen of either clarithromycin or azithromycin, plus rifampicin and ethambutol. Treatment typically lasts at least 12 months.

Although studies have not yet identified an optimal regimen or confirmed that any therapeutic regimen produces sustained clinical benefit for patients with disseminated MAC, the Task Force concluded that the available information indicated the need for treatment of disseminated MAC. The Public Health Service therefore recommends that regimens be based on the following principles:

- Treatment regimens outside a clinical trial should include at least two agents.

- Every regimen should contain either azithromycin or clarithromycin; many experts prefer ethambutol as a second drug. Many clinicians have added one or more of the following as second, third, or fourth agents: clofazimine, rifabutin, rifampin, ciprofloxacin, and in some situations amikacin. Isoniazid and pyrazinamide are not effective for the therapy of MAC.

- Therapy should continue for the lifetime of the patient if clinical and microbiologic improvement is observed.

Clinical manifestations of disseminated MAC—such as fever, weight loss, and night sweats—should be monitored several times during the initial weeks of therapy. Microbiologic response, as assessed by blood culture every 4 weeks during initial therapy, can also be helpful in interpreting the efficacy of a therapeutic regimen.Most patients who ultimately respond show substantial clinical improvement in the first 4–6 weeks of therapy. Elimination of the organisms from blood cultures may take somewhat longer, often requiring 4–12 weeks.

People with AIDS are given macrolide antibiotics such as azithromycin for prophylactic treatment.

People with HIV infection and less than 50 CD4+ T-lymphocytes/uL should be administered prophylaxis against MAC. Prophylaxis should be continued for the patient's lifetime unless multiple drug therapy for MAC becomes necessary because of the development of MAC disease.

Clinicians must weigh the potential benefits of MAC prophylaxis against the potential for toxicities and drug interactions, the cost, the potential to produce resistance in a community with a high rate of tuberculosis, and the possibility that the addition of another drug to the medical regimen may adversely affect patients' compliance with treatment. Because of these concerns, therefore, in some situations rifabutin prophylaxis should not be administered.

Before prophylaxis is administered, patients should be assessed to ensure that they do not have active disease due to MAC, M. tuberculosis, or any other mycobacterial species. This assessment may include a chest radiograph and tuberculin skin test.

Rifabutin, by mouth daily, is recommended for the people's lifetime unless disseminated MAC develops, which would then require multiple drug therapy. Although other drugs, such as azithromycin and clarithromycin, have laboratory and clinical activity against MAC, none has been shown in a prospective, controlled trial to be effective and safe for prophylaxis. Thus, in the absence of data, no other regimen can be recommended at this time.The 300-mg dose of rifabutin has been well tolerated. Adverse effects included neutropenia, thrombocytopenia, rash, and gastrointestinal disturbances.

Treating fever in people with sepsis does not affect outcomes.

Monoclonal and polyclonal preparations of intravenous immunoglobulin (IVIG) do not lower the rate of death in newborns and adults with sepsis. Evidence for the use of IgM-enriched polyclonal preparations of IVIG is inconsistent. A 2012 Cochrane review concluded that N-acetylcysteine does not reduce mortality in those with SIRS or sepsis and may even be harmful.

Recombinant activated protein C (drotrecogin alpha) was originally introduced for severe sepsis (as identified by a high APACHE II score), where it was thought to confer a survival benefit. However, subsequent studies showed that it increased adverse events—bleeding risk in particular—and did not decrease mortality. It was removed from sale in 2011. Another medication known as eritoran also has not shown benefit.

In some studies, the bacteria found in patients with HCAP were more similar to HAP than to CAP; compared to CAP, they could have higher rates of "Staphylococcus aureus" ("S. aureus") and "Pseudomonas aeruginosa", and less "Streptococcus pneumoniae" and "Haemophilus influenzae". In European and Asian studies, the etiology of HCAP was similar to that of CAP, and rates of multi drug resistant pathogens such as "Staphylococcus aureus" and "Pseudomonas aeruginosa" were not as high as seen in North American studies. It is well known that nursing home residents have high rates of colonization with MRSA. However, not all studies have found high rates of S. aureus and gram-negative bacteria. One factor responsible for these differences is the reliance on sputum samples and the strictness of the criteria to discriminate

between colonising or disease-causing bacteria. Moreover, sputum samples might be less frequently obtained in the elderly.Aspiration (both of microscopic drops and macroscopic amounts of nose and throat secretions) is thought to be the most important cause of HCAP. Dental plaque might also be a reservoir for bacteria in HCAP.

Bacteria have been the most commonly isolated pathogens, although viral and fungal pathogens are potentially found in immunocompromised hosts (patients on chronic immunosuppressed medications, solid organ and bone marrow transplant recipients). In general, the distribution of microbial pathogens varies among institutions, partly because of differences in patient population and local patterns of anti microbial resistance in hospitals and critical care units' Common bacterial pathogens include aerobic GNB, such as "Pseudomonas aeruginosa", "Acinetobacter baumanii", "Klebsiella pneumoniae", "Escherichia coli" as well as gram-positive organisms such as "Staphylococcus aureus". In patients with an early onset pneumonia (within 5 days of hospitalization), they are usually due to anti microbial-sensitive bacteria such as "Enterobacter" spp, "E. coli", "Klebsiella" spp, "Proteus" spp, "Serratia mare scans", community pathogens such as "Streptococcus pneumoniae, Haemophilus influenzae", and methicillin-sensitive "S. aureus" should also be considered.

Pneumonia that starts in the hospital tends to be more serious than other lung infections because: people in the hospital are often very sick and cannot fight off germs. The types of germs present Ina hospital are often more dangerous and more resistant to treatment than those outside in the community. Pneumonia occurs more often in people who are using a respirator. This machine helps them breathe. Hospital-acquired pneumonia can also be spread by health care workers, who can pass germs from their hands or clothes from one person to another. This is why hand-washing, wearing grows, and using other safety measures is so important in the hospital.

Early recognition and focused management may improve the outcomes in sepsis. Current professional recommendations include a number of actions ("bundles") to be followed as soon as possible after diagnosis. Within the first three hours someone with sepsis should have received antibiotics and, intravenous fluids if there is evidence of either low blood pressure or other evidence for inadequate blood supply to organs (as evidenced by a raised level of lactate); blood cultures also should be obtained within this time period. After six hours the blood pressure should be adequate, close monitoring of blood pressure and blood supply to organs should be in place, and the lactate should be measured again if initially, it was raised. A related bundle, the "Sepsis Six", is in widespread use in the United Kingdom; this requires the administration of antibiotics within an hour of recognition, blood cultures, lactate and hemoglobin determination, urine output monitoring, high-flow oxygen, and intravenous fluids.

Apart from the timely administration of fluids and antibiotics, the management of sepsis also involves surgical drainage of infected fluid collections and appropriate support for organ dysfunction. This may include hemodialysis in kidney failure, mechanical ventilation in lung dysfunction, transfusion of blood products, and drug and fluid therapy for circulatory failure. Ensuring adequate nutrition—preferably by enteral feeding, but if necessary, by parenteral nutrition—is important during prolonged illness. In those with high blood sugar levels, insulin to bring it down to 7.8–10 mmol/L (140–180 mg/dL) is recommended with lower levels potentially worsening outcomes. Medication to prevent deep vein thrombosis and gastric ulcers also may be used.

Vaccination helps prevent bronchopneumonia, mostly against influenza viruses, adenoviruses, measles, rubella, streptococcus pneumoniae, haemophilus influenzae, diphtheria, bacillus anthracis, chickenpox, and bordetella pertussis.

Micro-organisms are known to survive on inanimate ‘touch’ surfaces for extended periods of time. This can be especially troublesome in hospital environments where patients with immunodeficiencies are at enhanced risk for contracting nosocomial infections.

Touch surfaces commonly found in hospital rooms, such as bed rails, call buttons, touch plates, chairs, door handles, light switches, grab rails, intravenous poles, dispensers (alcohol gel, paper towel, soap), dressing trolleys, and counter and table tops are known to be contaminated with "Staphylococcus", MRSA (one of the most virulent strains of antibiotic-resistant bacteria) and vancomycin-resistant "Enterococcus" (VRE). Objects in closest proximity to patients have the highest levels of MRSA and VRE. This is why touch surfaces in hospital rooms can serve as sources, or reservoirs, for the spread of bacteria from the hands of healthcare workers and visitors to patients.

A number of compounds can decrease the risk of bacteria growing on surfaces including: copper, silver, and germicides.

The methods used differ from country to country (definitions used, type of nosocomial infections covered, health units surveyed, inclusion or exclusion of imported infections, etc.), so the international comparisons of nosocomial infection rates should be made with the utmost care.

Antibiotics do not help the many lower respiratory infections which are caused by parasites or viruses. While acute bronchitis often does not require antibiotic therapy, antibiotics can be given to patients with acute exacerbations of chronic bronchitis. The indications for treatment are increased dyspnoea, and an increase in the volume or purulence of the sputum. The treatment of bacterial pneumonia is selected by considering the age of the patient, the severity of the illness and the presence of underlying disease. Amoxicillin and doxycycline are suitable for many of the lower respiratory tract infections seen in general practice.

Mycoplasma is found more often in younger than in older people.

Older people are more often infected by Legionella.

When comparing the bacterial-caused atypical pneumonias with these caused by real viruses (excluding bacteria that were wrongly considered as viruses), the term "atypical pneumonia" almost always implies a bacterial cause and is contrasted with viral pneumonia.

Known viral causes of atypical pneumonia include respiratory syncytial virus (RSV), influenza A and B, parainfluenza, adenovirus, severe acute respiratory syndrome (SARS)

and measles.

ILI occurs in some horses after intramuscular injection of vaccines. For these horses, light exercise speeds resolution of the ILI. Non-steroidal anti-inflammatory drugs (NSAIDs) may be given with the vaccine.