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December 2019 | Published by RCPA

Issue #098

The risks of over diagnosing Community Acquired Pneumonia

The risks of over diagnosing Community Acquired Pneumonia

Community acquired pneumonia (CAP) is one of the most common infectious disease presentations and is an important cause of mortality and morbidity worldwide.[1] We spoke with Dr Jenny Robson Pathologist-in-Charge of Sullivan Nicolaides Pathology's Department of Microbiology and Molecular Pathology to understand more.

“The infections that cause pneumonia inflame the air sacs in one or both lungs. When pneumonia occurs in individuals who are not in hospital or have been in hospital for less than 48 hours, it is referred to as CAP. Patients with CAP usually present with acute respiratory symptoms such as a cough, shortness of breath, chest pain, fever and occasionally sputum production. In some patients, symptoms may also include diarrhoea and headache or, particularly in the elderly, clinical features may be nonspecific.

“CAP is more common in older adults, but it can affect people of any age and can be very serious, especially in older adults or people with other health problems. Risk factors include, increasing age, smoking and presence of chronic diseases, such as chronic lung disease, heart disease and diabetes,” said Dr Robson.

It is important to differentiate pneumonia from other respiratory infections such as bronchitis, pharyngitis, and viral type illnesses that don’t affect the lower airways. Acute bronchitis for example usually does not require antibiotic treatment. CAP is most commonly cause by bacteria, but can also be caused by viruses, fungi, or bacteria-like organisms. Worldwide, Streptococcus pneumoniae is the bacterium that is most often responsible for CAP in adults. Whilst CAP is a common condition, it appears to be over-diagnosed and it is argued that this may be adding to the problems of overuse of antibiotics, leading to bacterial resistance in the community and greater costs and complications in individuals. Most cases of non-severe CAP can be treated for 5 to 7 days; even 3 days may be sufficient. However, most patients with CAP are receiving much longer courses of therapy.[2]

“In this time of great concern for widespread antimicrobial resistance, it’s important not to use unnecessary broad-spectrum antibiotics. Careful assessment is required to determine the severity in all patients in order to guide the need for inpatient management and the most appropriate course and duration of antibiotics. CAP is diagnosed by putting together the symptoms and signs which can include fever, rapid respiratory rate and high pulse rate. By listening to the chest, there are often signs that suggest there is consolidation of the alveoli or air sacs which become filled up with inflammatory cells and other secretions. CAP can then be confirmed on radiology either via an X-ray or a CT scan.

“Sputum cultures or direct detection of the pathogen using polymerase chain reaction (PCR) may shed light on the cause. The latter is particularly important to detect viruses such as influenza which then often obviate the need for antibiotics or atypical and difficult to culture bacteria such as Mycoplasma pneumonia, Chlamydia and Legionella species. For individuals who are really unwell, and may require hospitalisation, two sets of blood cultures might also be taken” said Dr Robson.

Annual influenza vaccination and five-yearly pneumococcal vaccination are recommended for people with risk factors and all those aged over 65 years. For Indigenous people, who have much higher rates of CAP than the non-Indigenous population, regular influenza and pneumococcal vaccination is recommended from the age of 50.[3]





[1] https://emedicine.medscape.com/article/234240-overview

[2] https://www.mja.com.au/journal/2017/206/7/controversies-diagnosis-and-management-community-acquired-pneumonia

[3] https://www.mja.com.au/journal/2002/176/7/3-community-acquired-pneumonia




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