The purpose of this study is to evaluate the added diagnostic value of a quantitative polymerase chain reaction targeting the lytA gene in detecting pneumococci in patients with community-acquired pneumonia.

Inclusion Criteria:

Patients:

• Age 18 years or above;

• Presentation at the emergency department (ED);

• Working diagnosis of CAP at the ED with the presence of at least two of the following criteria:

  1. New or worsened coughing;
  2. Production of purulent sputum or change in sputum colour;
  3. Temperature >38.0 ⁰C or ≤36.0 ⁰C (tympanic);
  4. Auscultatory findings consistent with pneumonia, including rales, evidence of pulmonary consolidation (dullness on percussion, bronchial breath sounds, rales, or egophony), or both;
  5. White blood cell count of >10x10^9 cells/L or <4x10^9 cells/L or >15% bands;
  6. C-reactive protein level ≥30mg/L;
  7. Dyspnea, tachypnea, (>20 breaths per minute), or hypoxemia (arterial pO2 <60mmHg or peripheral O2 saturation <90%).

• New consolidation(s) on the chest radiograph or computed tomography (CT);

• No other explanation for the signs and symptoms;

Control group 1 - Related controls

• Being aged 18 years or above;
• Close relative of the patient: relative defined as living in the same house as the CAP patient or daily contact;
• Is at the hospital at the moment of inclusion of the CAP patient or is willing to come for testing within 7 days;

Control group 2 - Unrelated healthy individuals

• Being aged 18 years or above;
• Subject with a preoperative appointment with the anaesthiologist for a planned surgical procedure;
• Age matched to a included CAP patient (+-10 years);
• Time matched to a included CAP patient (up to 14 days after inclusion of the CAP patient);
• Gender matched to a included CAP patient.

Control group 3 - Patients with stable COPD

• Being aged 18 years or above;
• Diagnosis of COPD confirmed with spirometry (GOLD criteria 2017)(76);
• Stable disease.

Control group 4 - Patients with exacerbation of COPD

• Being aged 18 years or above;
• Diagnosis of COPD confirmed with spirometry (GOLD criteria 2017)(76);
• Diagnosis of exacerbation of COPD: defined as an acute event characterised by a worsening of the patient's respiratory symptoms that is beyond normal day-to-day variations and leads to a change in medication (76).
• Presentation at emergency department with the suspicion of an exacerbation.

Exclusion Criteria:

In general:

• Recent pneumonia (< 1 month) or pneumonia in last 3 months with known pneumococcal aetiology with one of current diagnostics;
• Was included in the study group before;
• Not capable of understanding information needed to sign informed consent.

Patients:

• Aspiration pneumonia;
• Hospitalisation for two or more days in the last 14 days;
• History of cystic fibrosis.

For all control groups:

• Fits inclusion criteria for patient group;
• Present or recent hospitalisation (14 days);
• Fits inclusion criteria for patient group;
• Use of antibiotics in the last 14 days, including maintenance antibiotic therapy.

Control group 1 and 2 - Related healthy controls and unrelated healthy individuals

• Active infectious respiratory complaints defined as defined as two or more respiratory symptoms (cough, nasal congestion, runny nose, sore throat or sneezes);
• Temperature >38.0 ⁰C;
• Fits inclusion criteria for control group 3 or 4;
• Chronic pulmonary disease: COPD, asthma, cystic fibrosis, bronchiectasis.

Control group 3 - Patients with stable COPD

• Temperature >38.0 ⁰C;
• Stable disease;
• Fits inclusion criteria for control group 4;
• Recent exacerbation (<1 month) defined as increased respiratory symptoms with need of antibiotic and/or corticosteroid therapy;
• History of cystic fibrosis.

Control group 4 - Patients with exacerbation of COPD

• Current pneumonia;
• Recent exacerbation (<1 month) defined as increased respiratory symptoms with need of antibiotic and/or corticosteroid therapy;
• Fits inclusion criteria for control group 3;
• History of cystic fibrosis.

Patient group: Adult patients ≥18 years with diagnosis of CAP at the emergency department (ED).

Control groups (without CAP):

• Related controls (inclusion at ED)
• Unrelated healthy adults (inclusion at an outpatient preoperative appointment for any elective surgery)
• Stable COPD patients (inclusion at outpatient clinic for pulmonary diseases)
• COPD patients with an AECOPD (inclusion at ED)