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Overview of Pneumonia

Pneumonia is an infection of the lungs.

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It can be caused by bacteria, viruses or fungi. Antibiotics have reduced the fatalities associated from pneumonia many fold. Prior to the discovery of antibiotics, about one-third of people who developed pneumonia died from the infection. There has been a steep decline in the number of deaths due to pneumonia since 1940, when penicillin became widely available. In the later years, the decline was increasing annually probably due to the increased coverage of medical services across the population. There was a rise in the number of deaths in 1957 due to the influenza A pandemic. In 2000, the number of patients in a homecare setting with admission in the hospital with a primary diagnosis of pneumonia in USA was 20,300 (1.5%).2 In a 2004 survey, pneumonia and influenza together were the 8th leading cause of death in the USA .3

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Signs and Symptoms of Pneumonia

The signs and symptoms of pneumonia are basically of the upper respiratory infection. Most people initially have symptoms of a cold followed by a high fever (sometimes as high as 104ºF), shaking chills, and a cough with sputum production. The sputum is usually discolored and sometimes bloody. Patients may have breathing difficulties and shortness of breath. Chest pain may develop if the outer aspects of the lung are involved. This pain is known as pleuritic pain and is usually sharp and worsens when taking a deep breath. In other cases of pneumonia, there can be a slow onset of symptoms. A worsening cough, headaches and muscle aches may be the only symptoms. In some people with pneumonia, coughing is not a major symptom because the infection is located in areas of the lung away from the larger airways.

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While the above symptoms may be present in most of the population, in some populations the symptoms may not be very obvious. Children and babies who develop pneumonia often do not have any specific signs of a chest infection, but develop a fever, appear quite ill, and can become lethargic. Elderly people may also have few symptoms with pneumonia. Caution has to be exercised in diagnosing and treating these patients because delays can prove fatal.

Diagnosis of Pneumonia

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In most cases, pneumonia may be suspected clinically when the doctor examines the patient and hears coarse breathing or crackling sounds when listening to a portion of the chest with a stethoscope. There may be wheezing, or the sounds of breathing may be faint in a particular area of the chest. A chest X-ray is usually ordered to confirm the diagnosis of pneumonia.

To confirm the diagnosis and the organism, sputum samples can be collected and examined under the microscope. To further confirm the finding of a microorganism, a sample of the sputum can be grown in special incubators, and the offending bacteria can be subsequently identified. It is important to understand that the sputum specimen must contain little saliva from the mouth and be delivered to the laboratory fairly quickly. Otherwise, overgrowth of noninfecting bacteria may predominate.

A blood test is done to assess the severity of the infection. A white blood cell count (WBC) may be performed. An individual’s white blood cell count can often give a hint as to the severity of the pneumonia and whether it is caused by bacteria or a virus.

Bronchoscopy is a procedure in which a bronchoscope (thin, flexible, tube with fibreoptics to view the structures at the front of the tube) is inserted into the nose or mouth after a local anesthetic is administered to eliminate or reduce the pain. The breathing passages can then be directly examined by the doctor, and specimens from the infected part of the lung can be obtained.

Legionella urinary antigen test is done if there is clinical suspicion of Legionnaire’s disease.

Treatment Options for Pneumonia

Guidelines for the treatment of diseases are published by the related societies in the respective nations. These are based on prior evidence of clinical benefit from specific therapies. The evidence is graded to provide a clear understanding.

  • Level I—High level of evidence. Evidence from well-conducted, randomized controlled trials.
  • Level II—Moderate level of evidence. Evidence from well-designed, controlled trials without randomization. (Randomization is a process where research participants are assigned to either the investigational group or the control group randomly (by chance not by choice). The goal of randomization is to produce comparable groups in terms of general participant characteristics, such as age or gender, and other key factors that affect the probable course the disease would take. A randomized, controlled trial is considered the most reliable and impartial method of determining what medical interventions work the best).
  • Level III – Low level of evidence. Evidence from case studies and expert opinion. In some instances, therapy recommendations come from antibiotic susceptibility data without clinical observations.

In USA, two of the most widely referenced guidelines for the treatment of CAP are those of the Infectious Diseases Society of America (IDSA) and the American Thoracic Society (ATS).4 In response to confusion regarding differences between their respective guidelines, the IDSA and the ATS convened a joint committee to develop a unified CAP guideline document. The guidelines can be adapted to suit local regulations and practices.

Outpatient Treatment

1.Previously healthy and no use of antimicrobials within the previous 3 months

  • A macrolide (strong recommendation; level I evidence)
  • Doxycyline (weak recommendation; level III evidence)

2.Presence of comorbidities such as chronic heart, lung, liver or renal disease; diabetes mellitus; alcoholism; malignancies; asplenia; immunosuppressing conditions or use of immunosuppressing drugs; or use of antimicrobials within the previous 3 months (in which case an alternative from a different class should be selected)

  • A respiratory fluoroquinolone (moxifloxacin, gemifloxacin, or levofloxacin [750 mg]) (strong recommendation; level I evidence)
  • A β-lactam plus a macrolide (strong recommendation; level I evidence)

3.In regions with a high rate (125%) of infection with high-level macrolide-resistant Streptococcus pneumoniae, consider the use of alternative agents listed above in (2) for patients without comorbidities (moderate recommendation; level III evidence).

Inpatients and Non-ICU Treatment

  • A respiratory fluoroquinolone (strong recommendation; level I evidence)
  • A β-lactam plus a macrolide (strong recommendation; level I evidence)
  • Inpatients, ICU treatment

A β-lactam (cefotaxime, ceftriaxone, or ampicillin-sulbactam) plus either azithromycin (level II evidence) or a respiratory fluoroquinolone (level I evidence) (strong recommendation) (for penicillin-allergic patients, a respiratory fluoroquinolone and aztreonam are recommended)

Special Concerns

If community acquired-methicillin resistant Staphylococcus aureus (CA-MRSA) is a consideration, add vancomycin or linezolid (moderate recommendation; level III evidence).


Pneumonia is a serious illness that requires a visit to the doctor to assess it’s severity and start therapy. If diagnosed and treated at the right time, it is a very easily manageable condition. In case of an elderly person or babies or children or immunocompromised people developing upper respiratory signs and symptoms, medical attention becomes necessary to rule out or treat pneumonia.


1.Dowell SF, Kupronis BA, Zell ER, Shay DK. Mortality from pneumonia in children in the United States, 1939 through 1996, N Engl J Med. 2000; 342: 1399–1407.

2.The National Home and Hospice Care Survey, United States, 2000.

3.National Vital Statistics Reports, Vol. 55, No. 19, August 21, 2007.

4.Mandell LA,, Wunderink RG, Anzueto A, Bartlett JG, Campbell GD, Dean NC,  et al. Infectious Diseases Society of America/American Thoracic Society Consensus Guidelines on the Management of Community-Acquired Pneumonia in Adults, Clinical Infectious Diseases 2007; 44: S27–72.

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Written by: Saptakee sengupta
Date last updated: April 17, 2015