NICE guidelines suggest cases of community acquired pneumonia (CAP) in hospital have blood and sputum cultures and legionella and pneumococcal antigen tests be considered in specific cases. Local guidelines advise respiratory viral swabs, sputum and blood culture in specific cases and urinary antigen tests only in severe cases. We assessed the frequency and appropriateness of microbiological testing in CAP.


The electronic records of admissions to St Thomas’ Hospital, London in January 2019 were scrutinised to identify cases of CAP. The severity of each case was categorized using CRB65 scoring. Microbiological tests and their results were analysed.


64 cases of CAP were identified. Severe disease (CRB>/= 2) was present in 31%. Respiratory viral/flu swabs were sent in 76% of cases and were positive in 39% of these cases [12 (63%) were influenza]. Sputum culture was collected in 39% of cases and revealed pathogens in 24% of these. Urinary pneumococcal antigen was sent in 7 cases of non-severe disease and 1 case of severe disease and was positive in 25% of those tested. Legionella urinary antigen tests were sent in 6 cases, only 2 of whom had reasons documented for sending the test; all were negative. Blood cultures were sent in 69% of cases (44 patients) and none revealed pathogens.


During the influenza season the most useful microbiological test was the respiratory viral swab. Sputum culture is a cheap test that could be used more often. Expensive legionella antigen tests were performed inappropriately.

  • This is an open-access article distributed under the terms of the Creative Commons Attribution License.

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