VERDICTA severe complication of COVID-19 is viral pneumonia. Distinguishing viral pneumonia from bacterial pneumonia is difficult in the community. In some cases, they could co-exist, increasing the chance of a more unfortunate outcome. However, there may be important clues in the history and the examination that can help differentiate the two. Recent guidance from NICE (UK) will support clinicians in this process.

BACKGROUNDCommunity-acquired pneumonia (CAP) can be caused by viruses, bacteria and fungi (Figure 1).

Viral pneumonia is a common complication of influenza-like illnesses and is a complication of SARS-COV-2. Viral pneumonia may clear up on its own; however, when severe, it can be life-threatening. Viruses are generally not as common a cause of CAP as some bacteria. However, as well as being a primary pathogen, viruses can be a co-pathogen with bacteria, particularly in those with severe illness requiring admission to ICU and in ventilator-associated pneumonia.

CURRENT EVIDENCEBacterial community-acquired pneumonia and viral pneumonia may coexist. A systematic review including 31 studies (n=10, 762 patients) found that 25% of patients with CAP had viral infections (95% CI 22–28%), this increased to 44% in studies where >50% had a lower respiratory sample. The review reported that the interaction of CAP and viral infection doubled mortality: odds of death in patients with bacterial and viral infection (OR 2.1, 95% CI 1.32 to 3.31) (10 studies).

Coronavirus has also been shown to occur with CAP. In a 2010 case-control study conducted in Israel (n=183 adults with CAP, 450 controls), coronaviruses were identified in 24 (13%) patients with CAP, compared with 17 (4%) in control subjects.

The Development of a Bedside Predictive Model and Scoring System in 103 consecutive patients classified as having virus-like (48), bacterial (37) and unknown (18) pneumonia found that the independent predictors for bacterial pneumonia were:

Acute onset of symptoms (OR 31; 95% CI, 6-150),

Age > 65 or

Comorbidity (OR 6.9; 95% CI, 2-23),

Leukocytosis or leukopenia (OR 2; 95% CI, 0.6-7).

The sensitivity and specificity of the score to identify patients with bacterial pneumonia were 89% and 94%, respectively. The sample was small and the results might not be generalizable outside of the ED setting and they have not been validated.

A meta-analysis included 12 studies of 2408 adult patients with documented bacterial versus non-bacterial aetiology of CAP. For the 8 studies using a procalcitonin cut-off of 0.5 µg/L, the pooled sensitivity and specificity estimates were 55% (95% CI, 37-71%) and 76% (95% CI, 62–86%), respectively. The review found that the sensitivity and specificity were both too low and variable for the results to be confidently used in the decision-making.

Meet the increased calorie needs of the patient, secondary to the increased respiratory effort.

MANAGING SUSPECTED OR CONFIRMED PNEUMONIA IN ADULTS IN THE COMMUNITY DURING THE COVID-19 PANDEMICIn the UK, the National Institute for Health and Care Excellence (NICE) has produced rapid guidelines for managing suspected or confirmed pneumonia in adults in the community during the COVID-19 pandemic. The guidance makes specific reference to differentiating viral COVID-19 pneumonia from bacterial pneumonia as follows:

COVID‑19 viral pneumonia may be more likely if the patient:

A bacterial cause of pneumonia may be more likely if the patient:

presents with a history of typical COVID‑19 symptoms for about a week

has severe muscle pain (myalgia)

has a loss of sense of smell (anosmia)

is breathless but has no pleuritic pain

has a history of exposure to known or suspected COVID‑19, such as a household or workplace contact.

becomes rapidly unwell after only a few days of symptoms

does not have a history of typical COVID‑19 symptoms

has pleuritic pain

has purulent sputum.

Expert opinion added suggestions include*

Viral pneumonia more likely if

Bacterial Pneumonia more likely if

Insidious onset

Lower temperature

Tachycardia or tachypnea out of proportion to the temperature

A paucity of physical findings on pulmonary exam disproportionate to the level of disability

If management can be maintained in the community, NICE goes on to suggest that:

As COVID‑19 pneumonia is caused by a virus, antibiotics are ineffective.

Do not offer an antibiotic for treatment or prevention of pneumonia if:

COVID‑19 is likely to be the cause and

symptoms are mild.

Offer an oral antibiotic for the treatment of pneumonia in people who can or wish to be treated in the community if:

the likely cause is bacterial or

it is unclear whether the cause is bacterial or viral and symptoms are more concerning or

they are at high risk of complications because, for example, they are older or frail, or have a pre-existing comorbidity such as immunosuppression or significant heart or lung disease (for example bronchiectasis or COPD), or have a history of severe illness following a previous lung infection.

Start antibiotic treatment as soon as possible, taking into account any different methods needed to deliver medicines to patients during the COVID‑19 pandemic

Do not routinely offer a corticosteroid * unless the patient has other conditions for which these are indicated, such as asthma or COPD.

Safety net and review as appropriate

*Corticosteroids were widely used during the 2002-3 SARS outbreak. However, in a subsequent systematic review, including 29 low-quality studies of steroid use, reported on 25 studies that were inconclusive and four reported possible harm from steroid use. A further evidence review did not support corticosteroid treatment, reporting no evidence of net benefit with corticosteroids in “respiratory infection due to RSV, influenza, SARS-CoV, or MERS-CoV”, and that corticosteroids probably impair clearance of SARS-CoV.

CONCLUSIONSDistinguishing viral pneumonia from bacterial pneumonia is difficult. There are important cues in history and the examination that can help differentiate the two. The clinician should be aware that the coexistence of viral and bacterial pneumonia increases the risk of death.

Disclaimer: The article has not been peer-reviewed; it should not replace individual clinical judgement and the sources cited should be checked. The views expressed in this commentary represent the views of the authors and not necessarily those of the host institution, the NHS, the NIHR, or the Department of Health and Social Care. The views are not a substitute for professional medical advice.

AUTHORS

Carl Heneghan is the Editor in Chief BMJ EBM and Professor of EBM, Centre for Evidence-Based Medicine in the Nuffield Department of Primary Care Health Sciences, University of Oxford

Annette Pluddemann Course Director of the MSc in Evidence-Based Health Care and also a Senior Research Fellow in the Centre for Evidence-Based Medicine

Kamal R. Mahtaniis a GP, Associate Professor and Deputy Director of the Centre for Evidence-Based Medicine, Nuffield Department of Primary Care Health Sciences, University of Oxford. He is also an Associate Editor at the BMJ Evidence-Based Medicine journal and Director of The Evidence-based Healthcare MSc in Systematic Reviews