Diagnosis Protocol

It is not necessary to perform a chest radiograph unless: The diagnosis is in doubt and a chest radiograph will help in a differential diagnosis and management of the acute illness; Progress following treatment for suspected CAP is not satisfactory at review; The patient is considered at risk of underlying lung pathology such as lung cancer.

Should have a chest radiograph performed as soon as possible to confirm or refute the diagnosis. The objective of any service should be for the chest radiograph to be performed in time for antibiotics to be administered within 4 hours of presentation to hospital should the diagnosis of CAP be confirmed.

The chest radiograph need not be repeated prior to hospital discharge in those who have made a satisfactory clinical recovery from CAP.

A chest radiograph should be arranged after about 6 weeks.

Further investigations which may include bronchoscopy should be considered.

It is the responsibility of the hospital team to arrange the follow-up plan with the patient and the general practitioner.

General investigations are not necessary. Pulse oximeters allow for simple assessment of oxygenation. General practitioners, particularly those working in out of hours and emergency assessment centres, should consider their use.

Pulse oximetry should be available in all locations where emergency oxygen is used.

Should have the following tests performed on admission: Oxygenation saturations and, where necessary, arterial blood gases in accordance with the BTS Guideline for Emergency Oxygen Use in Adult Patients; Chest radiograph to allow accurate diagnosis; Urea and electrolytes to inform severity assessment; C-reactive protein to aid diagnosis and as a baseline measure; Full blood count; Liver function tests.

Microbiological tests should be performed on all patients with moderate and high severity CAP. The extent of investigation in these patients being guided by severity.

The extent of microbiological investigations should be guided by clinical factors (age, co-morbid illness, severity indicators), epidemiological factors, and prior antibiotic therapy.

Empirical antibiotics should be changed to the appropriate pathogen-focused agent, unless there are legitimate concerns about dual pathogen infection.

Microbiological investigations are not recommended routinely.

Examination of sputum should be considered.

Examination of sputum for Mycobacterium tuberculosis should be considered.

Urine antigen investigations, PCR of upper (eg. nose and throat swabs) or lower (eg. sputum) respiratory tract samples or serological investigations may be considered.

Blood cultures are recommended, preferably before antibiotic therapy is commenced.

Blood cultures may be omitted.

Sputum samples should be sent for culture and sensitivity tests. Specimens should be transported rapidly to the laboratory.

Culture of sputum or other lower respiratory tract samples should also be performed.

Sputum cultures for Legionella spp should always be attempted in order to provide isolates for epidemiological typing and comparison with isolates from putative environmental sources.

Where sputum Gram stain is available, laboratories should offer a reliable Gram stain as, occasionally, this can give an immediate indicator of the likely pathogen.

Routine performance or reporting of sputum Gram-stain on all patients is unnecessary but can aid the laboratory interpretations of culture results.

Are rarely helpful in establishing a diagnosis.

Should adhere to strict and locally agreed criteria for interpretation and reporting of results.

Pneumococcal urine antigen tests should be performed.

A rapid testing and reporting service for pneumococcal urine antigen should be available to all hospitals admitting patients with CAP.

Investigations for legionella pneumonia are recommended.

Legionella urine antigen tests should be performed.

A rapid testing and reporting service for legionella urine antigen should be available to all hospitals admitting patients with CAP.

Specimens of respiratory secretions, including sputum, should be sent. The clinician should specifically request legionella culture on laboratory request forms.

Legionella cultures should be routinely performed on invasive respiratory samples (eg obtained by bronchoscopy) from patients with CAP.

Clinicians should send respiratory specimens, such as sputum and request legionella culture. This is to aid outbreak and source investigation with the aim of preventing further cases.

Where available, PCR of respiratory tract samples, such as sputum, should be the method of choice.

A throat swab for Mycoplasma pneumoniae PCR is recommended.

Requires considerable caution.

Chlamydophila antigen and/ or PCR detection tests should be available.

The complement fixation test remains the most suitable and practical serological assay. There is no currently available serological test that can reliably detect acute infection due to C pneumoniae.

This is preferred to serological investigations.

Paired serology tests can be considered. The date of onset of symptoms should be clearly indicated on all serological request forms.

Serological tests may be extended to all patients admitted to hospital with CAP. The criteria for performing serology tests in these circumstances should be agreed locally between clinicians, laboratories and public health.