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Community Acquired Pneumonia: Advances in the Cause and Management

Community acquired pneumonia (CAP) is a common cause of morbidity and mortality worldwide. Recent advances in research and technology have helped in the understanding of the disease which in turn aids treatment and management.

Community acquired pneumonia is one of the main causes of hospital admissions and healthcare professionals encounter community acquired pneumonia in different forms in their practices. Effective treatment and management of community acquired pneumonia require accurate diagnosis and determination of the causative agent (pathogen). There has been a shift over the last 20 years in how community acquired pneumonia is diagnosed and managed. A review that was recently published in the British Medical Journal by Wunderink and Waterer looked at new developments in the management of CAP in hospital patients. They reviewed 25 original articles on community acquired pneumonia in adults that were published between January 2007 and January 2017. Their findings can be summarized under the following developments:

Advances in diagnosis

Chest radiography has been the gold standard for diagnosis of CAP but this has recently been challenged by the use of current technologies such as Computed Tomography (CT) scans and Magnetic Resonance Imaging (MRI). Even though CT scanners may not be available in every healthcare setting, the rising use of this technology and its ability to scan as quickly as normal radiography coupled with its sensitivity and specificity makes it well suited as the technology of choice for the future. Point-of-care ultrasonography is another alternative since it can also confirm the presence of infiltrates and distinguish between other relevant abnormalities.

Recent understanding of causes of CAP

Conventional culture techniques have shown both bacterial and viral causes of CAP with Staphylococcus Pneumoniae being the most prominent. The past decade has seen considerable improvements in a test for pathogen detection in CAP including more sensitive and affordable molecular techniques such as nucleic acid amplification and deep sequencing. While different studies conflict on the most common pathogenic cause of CAP, a common observation was that at least a third of patients harbored two or more pathogens, mostly virus/bacteria combination. Other viral and bacterial causes of community acquired pneumonia have emerged over the years including metapneumovirus, coronaviruses, avian influenza, particularly H5N1 and H7N9, penicillin resistant S. pneumoniae and meticillin resistant S. aureus.

Management of CAP and other complications

Since the actual pathogenic cause of community acquired pneumonia is not always completely known, treatment is usually based on observation and experimentation and it is recommended that antibiotic treatment starts immediately after diagnosis. Several studies have compared monotherapy and combination therapy in the treatment of community acquired pneumonia in different settings and although treatment may vary from region to region and from case to case, β lactam/macrolide combination or a respiratory fluoroquinolone is generally recommended for an inpatient setting while a β lactam, macrolide, or tetracycline is recommended for outpatient settings unless contraindicated. Corticosteroids have also been studied and shown to reduce mortality from community acquired pneumonia, but due to the inadequacy of these studies coupled with the fact that steroids may be associated with other medical conditions, they are not recommended for patients with CAP. Further studies are required to completely understand its role and the type of patient with community acquired pneumonia that can benefit from steroid treatment.

The use of biomarkers like procalcitonin can aid clinical judgement in the management of community acquired pneumonia. Despite its limitations including the fact that it is not usually elevated in certain infections and its poor sensitivity in mixed bacterial and viral infection, procalcitonin may be useful in guiding duration of antibiotic therapy in settings where physicians routinely exceed the recommended duration.

Several studies have shown an association between community acquired pneumonia and increased risk of certain cardiovascular diseases. The mechanism by which community acquired pneumonia affects cardiovascular complications are not known but several possible explanations exist and have been used to guide treatment. Community acquired pneumonia survivors are known to have a long term increase in mortality risk which has been associated with increased cardiac disease including myocardial infarction and heart failure and as such, measures to reduce cardiac injury will be helpful in reducing the morbidity and mortality in community acquired pneumonia survivors.

Bundle of care

A group of interventions and processes known as “care bundles” have been designed to improve the outcome of community acquired pneumonia patients. Based on available research, CAP care bundles should include:

  • the use of CAP severity score to aid in clinical evaluation and determination of the site of care
  • rapid empiric antibiotic treatment
  • rapid resuscitation, including fluid resuscitation
  • encouraging early ambulation
  • tackling cardiovascular risk factors.

Our knowledge of the cause and management of community acquired pneumonia is ever improving. While better outcomes can be achieved through the use of therapeutic bundles, research in finding better treatment still continues and ongoing trials are looking into new diagnostic platforms, new antimicrobials, as well as treatment for severe community acquired pneumonia.

Written by Asongna T. Folefoc


Wunderink RG and Waterer G. “Advances in the causes and management of community acquired pneumonia in adults.” BMJ 2017;358:j2471 doi: 10.1136/bmj.j2471



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