American College of Physicians: Internal Medicine — Doctors for Adults ®


Community Acquired Pneumonia

From the December ACP Observer, copyright 2006 by the American College of Physicians.

Click here for a PDF version of Community Acquired Pneumonia

The latest thinking about community acquired pneumonia (CAP), the seventh leading cause of death in the U.S., is that many people can be effectively and safely treated at home.

"There is a lot of confusion about when to use the hospital," explained Michael S. Niederman, FACP, chair of the Department of Medicine and a pulmonary and critical care physician at Winthrop University Hospital in Mineola, N.Y. Dr. Niederman is author of ACP's PIER module on CAP.

In general, he said, the literature shows that doctors tend to be too cautious, opting to admit patients who don't need to be in the hospital to receive effective antibiotic therapy.

"Many patients are happier if they are managed out of the hospital, and it certainly costs less if they can safely be managed out of the hospital," he said. Before making a decision, ask these questions about patients' ability to handle home-based treatment: Do they need oxygen? Are they able to ingest food, water and medication? Do they have support? Can they get help if their symptoms worsen, and can they get adequate follow-up?

Some CAP experts recommend that physicians use one of several objective risk-assessment tools to help them decide about the site of care. One that has been validated is the Pneumonia Severity Index (PSI) and another is the simpler five-point prognostic scoring system called CURB-65 (which has recommendations consistent with the British Thoracic Society guidelines). New CAP treatment guidelines from the Infectious Diseases Society of America and the American Thoracic Society, expected to be published in early 2007, will recommend doctors use either the PSI or CURB-65 severity scoring systems.

"There is no hard and fast rule for when to hospitalize a CAP patient," said Dr. Niederman, "but it is safe for carefully selected patients not to be in the hospital if you make a good follow-up plan."

This edition of ACP Observer Special Focus is designed to help optimize your ability to diagnose, treat and manage patients with community acquired pneumonia.


Vaccinate all eligible patients against influenza yearly, preferably between early September and mid-November. For unvaccinated, high-risk patients during an influenza epidemic, consider antiviral chemoprophylaxis. Use amantadine and rimantadine against influenza A or oseltamivir and zanamivir against influenza A and B.

Administer pneumococcal vaccine to patients 65 and older, Alaskan natives, American Indian populations, long-term care facility residents, and people with chronic illnesses including congestive heart failure, COPD, diabetes, alcoholism, cirrhosis, cerebrospinal fluid leaks, or functional or anatomic asplenia.

Revaccinate once anyone initially vaccinated more than five years earlier or before the age of 65.

Consider vaccinating any hospitalized medical patient before discharge. While it is important to inform the patient, it is not necessary to explicitly obtain consent, and patients are unlikely to experience an adverse reaction from repeated vaccinations.


Take a careful history and look for the following respiratory and systemic symptoms:

  • cough, sputum production and color
  • pleuritic chest pain
  • dyspnea
  • chills, fever, night sweats
  • weight loss
  • confusion
  • weakness, lethargy
  • falling

Ask about duration of symptoms and look for poor oral intake and deterioration of a chronic illness, such as congestive heart failure.

Be aware that many older patients respond to infection differently from younger patients. They may exhibit a less intense immune response or fewer symptoms. They may be afebrile, and CAP can sometimes exacerbate comorbid illnesses. Bear in mind that CAP itself can be a clue to the presence of previously unrecognized serious comorbidity. Focus on chronic obstructive pulmonary disease (COPD), alcoholism, underlying heart disease, bronchiectasis, aspiration due to gastrointestinal or neurologic disease, poor dentition, injection drug use and the need for antibiotic therapy in the past three months.

Look for epidemiologic clues that suggest certain pathogens, including travel (consider endemic fungi in the southwestern U.S., or melioidosis or SARS in Southeast Asia or China), exposure to birds, bats, farm animals and rabbits, and epidemiologic information about the patient's residence that may suggest Legionella.

Although the pathogen causing CAP is unknown in at least half of cases, the most commonly identified ones are pneumococcus, H. influenzae, M. pneumoniae, C. pneumoniae, and Legionella. A variety of unusual or drug-resistant organisms can cause CAP. Elicit a history of risk factors for infection. With drug-resistant S. pneumoniae, ask about age over 65 years, b-lactam therapy within the past three months, alcoholism, immune-suppressive illness (including therapy with corticosteroids), multiple medical comorbidities or exposure to a child in a day care center. For enteric gram-negative bacteria, ask about residence in a nursing home, underlying cardiopulmonary disease, multiple medical comorbidities or recent antibiotic therapy. With P. aeruginosa, ask about structural lung disease (bronchiectasis) or corticosteroid therapy.

Health-care facility associated pneumonia should be considered in the presence of the following risk factors:

  • hospitalization or antibiotic therapy in the past 90 days,
  • residence in a long-term care facility,
  • chronic dialysis, or
  • outpatient wound care or home infusion therapy.

Prognosticate outcome by examining the patient for signs of pneumonia including crackles, bronchial breath sounds and evidence of pleural effusion. A poor outcome is associated with these specific findings, which should prompt hospitalization:

  • respiratory rate >30/min,
  • diastolic BP <60 mmHg,
  • systolic BP <90 mmHg,
  • heart rate >125/min,
  • temperature <35 C or >40 C.

Obtain a chest X-ray to confirm or rule out pneumonia and to identify complications, such as pleural effusion, cavitation or multilobar illness, which require a different approach to management. Limit laboratory testing in outpatients with CAP once the diagnosis of pneumonia has been established and appears to be mild to moderate in severity. If ordering lab tests, consider obtaining the following in addition to a chest X-ray, blood cultures and routine admission blood studies:

  • pulse oximetry,
  • arterial blood gas, especially in patients with COPD,
  • sputum culture in any patient at risk for infection with a drug-resistant or unusual pathogen,
  • immunochromatographic membrane test (BINAX NOW) of concentrated urine for pneumococcal antigen,
  • serologic testing for mycoplasma, Legionella and viruses if risk factors for these infections are present, or
  • Legionella urinary antigen for patients with severe CAP.


Although many patients with CAP can be safely managed in the outpatient setting, up to 20% require hospitalization. Hospitalize patients based on clinical judgment supplemented by prognostic scoring rules, such as the PSI or CURB-65.

The PSI measures the severity of illness and predicts the risk of mortality within 30 days of diagnosis. Classes 1-3 are considered low-risk categories with mortality risk ranging from 1% to 4%. The risk increased to 4%-10% for class 4 and 10%-30% for class 5. Home treatment is considered for patients in risk classes 1-3, while hospitalization is usually required for patients in higher risk classes. Using PSI can reduce the number of low-risk patients who are hospitalized, but physician judgment often supersedes the PSI.

The CURB-65 score considers these parameters: Confusion, urea nitrogen, respiratory rate, blood pressure and age 65 years or older. A score of two or higher usually indicates disease severe enough to warrant hospitalization. A PSI calculator is online.

Consider hospitalization for patients:

  • With multiple risk factors for a complicated course
  • Who are severely ill
  • With decompensated comorbid illness
  • Who have failed outpatient therapy
  • With complex social needs

Hospitalize patients who require intravenous antibiotics, oxygen, and intensive nursing care. Manage selected patients with nursing home acquired pneumonia with oral therapy in the nursing home, provided there is provision for careful serial observation and hydration. Consider using a validated pneumonia severity index as an adjunct to clinical judgment to triage patients. For more information, see Risk Factors for a Complicated Course with Community-acquired Pneumonia in PIER.

Use the British Thoracic Society (BTS) rule to identify patients with an increased risk of death. A score of two of more of the following criteria identifies a CAP patient with a higher risk of death:

  • respiratory rate >30/min,
  • diastolic BP <60 mm/Hg,
  • BUN >19.6 mg/dL,
  • confusion.

Alternatively, use the CURB-65 criteria to estimate mortality risk:

  • confusion,
  • blood urea nitrogen >19.6 mg/dL
  • respiratory rate >30 breaths per minute,
  • BP <90 mmHg systolic or <60 mmHg diastolic,
  • age 65 years or older.

While patients scoring none or one of the criteria have a 0% mortality rate, those with two or more have a mortality rate of 8.3%, and three or higher have a mortality rate of >20%.

Admit to the ICU any patient with CAP who requires mechanical ventilation or has septic shock. Consider ICU admission if at least 2 of the following are present: a PaO2/FiO2 ratio <250, multilobar infiltrates, or low systolic blood pressure; and consider the ICU for any patient who needs close observation or specific therapy only available in the ICU. Delays in ICU admission are associated with high mortality rates, especially if the patient needs mechanical ventilation. No prediction rule is completely accurate for determining ICU admission.


For patients requiring hospitalization, begin IV antibiotic therapy as soon as possible—preferably within four to six hours of the patient's arrival at the hospital—after rapid assessment of oxygenation and collection of routine blood work and blood cultures. Do not wait for a sputum sample for culture. Speed of initial therapy is important. Delays can lead to increased mortality, especially if the first dose of antibiotic therapy is delayed after arrival to the hospital.

Select drugs based on patient characteristics and site of care. For outpatients with no cardiopulmonary disease and no modifying factors that put the patient at risk for infection with drug-resistant pneumococcus or enteric gram-negatives, administer a newer macrolide (azithromycin or clarithromycin). An alternative is doxycycline.

For outpatients with cardiopulmonary disease or modifying factors who require more complex antibiotic therapy, choose an antipneumococcal quinolone (levofloxacin, gemifloxacin or moxifloxacin) or a b-lactam (cefuroxime, cefpodoxime, amoxicillin/clavulanate, high-dose amoxicillin) with a macrolide.

Avoid using the same class of antibiotics that the patient has received in the past three months. (Some data suggest that antibiotic exposures as much as six and 12 months earlier can affect pneumococcal resistance.) Limit quinolone monotherapy to patients who have either advanced age or comorbid conditions.

Non-ICU inpatients with cardiopulmonary disease and/or modifying factors should receive:

  • a new IV antipneumococcal quinolone (levofloxacin or moxifloxacin), or
  • an IV beta-lactam (cefotaxime, ceftriaxone, ampicillin/ sulbactam, high-dose ampicillin)/macrolide (IV or oral) combination.

It may be useful to use both regimens interchangeably in a given hospital to promote antibiotic heterogeneity and to minimize development of antibiotic resistance. (Quinolones most-to-least active against pneumococcus are gemifloxacin, moxifloxacin and levofloxacin.)

Treat ICU patients based on risk factors for P. aeruginosa.

  • If there are no risk factors, use an IV b-lactam (ceftriaxone or cefotaxime) plus either a macrolide (azithromycin) or a quinolone.
  • If risk factors exist, select an IV anti-pseudomonal b-lactam (cefepime, piperacillin/tazobactam, imipenem, meropenem) plus an IV quinolone effective against Pseudomonas (ciprofloxacin or high-dose levofloxacin).
  • An alternative is one of the above b-lactams with an aminoglycoside plus either an IV macrolide or an IV antipneumococcal quinolone.

If community-acquired methicillin resistant Staphylococcus aureus (CA-MRSA) is identified, add linezolid as monotherapy or consider adding clindamycin plus vancomycin in the therapeutic regimen.

For patients with severe CAP, consider also using drotrecogin alfa if shock and multiple organ failure are present. Consider systemic corticosteroid therapy if there may be adrenal insufficiency. Obtain pulmonary/critical care consultation to help manage severe CAP, to select and manage supportive care modalities, to evaluate patients with pleural effusion for possible thoracentesis or to consider the necessity of chest tube insertion. Request a thoracic surgery consultation to help manage patients who develop complicated parapneumonic effusion or empyema.

Evaluate how well hospitalized patients are responding to therapy and switch them to oral antibiotics as early as 24 to 48 hours after admission. Generally, half of all patients are switched by day 3. Switch to an oral regimen that covers all the organisms isolated in blood or sputum culture, such as an oral b-lactam/macrolide combination or a quinolone alone. If cultures do not justify continued dual therapy, patients responding to a b-lactam/macrolide combination can be continued on a macrolide alone.

Before switching to oral therapy, evaluate symptoms of cough, sputum production, dyspnea and fever. Some new data suggest the value of serially measuring serum procalcitonin levels to identify patients who do not need prolonged antibiotic therapy.

Patients with a good clinical response and a low likelihood of bacterial infection do not require prolonged therapy. Sometimes all therapy is stopped without switching to oral therapy in selected patients with mild-moderate CAP and a good clinical response to IV therapy.

Discharge most patients who are switched to oral therapy or no longer require antibiotics since there is no proven benefit of hospital observation if comorbid illnesses are stable during oral therapy; continued hospitalization only adds to the cost and the risk of hospital-related complications.


If outpatient therapy is warranted, teach patients how to monitor themselves for signs of nonresponsive or worsening illness:

Measure oral temperature every eight hours and notify the physician if it rises above 38.3 C (101 F) or does not fall below 37.2 C (99 F) after 48 hours.

Hydrate, and call if unable to drink at least one to two quarts of liquid daily.

Call the physician if there are symptoms of persistent fever, chest pain, severe or increasing shortness of breath or lethargy.

Stress the need to take antibiotics according to the prescribed time schedule and to finish all medication, even after feeling better.

Obtain a chest X-ray four to six weeks after initial therapy to establish a new baseline and to evaluate for non-resolution. Since radiographic resolution lags behind clinical resolution, avoid an early repeat X-ray in patients who are clinically doing well, particularly for patients older than 65, for patients with comorbidities, or if there was bacteremia, multilobar involvement or infection with enteric gram-negative bacteria, which are all predictors of slow resolution.

Identify risk factors for recurrent illness, and immunize patients with influenza or pneumococcal vaccine if necessary. Recurrent pneumonia can be due to aspiration, anatomic abnormalities (such as bronchiectasis) or immune deficiency.


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