Laboratory testing can be helpful in selected infants or children with community-acquired pneumonia (CAP). Pediatric patients with CAP who can be managed as outpatients often do not need additional laboratory testing. The authors are from the Pediatric Infectious Diseases Society and the Infectious Diseases Society of America.
Patient selection: infant > 3 months old or child with CAP
Microbiology tests may include:
(1) respiratory tract specimen for Gram stain and culture
(2) urinary antigen detection tests
(3) rapid tests for influenza or respiratory syncytial virus (RSV)
(4) serologic testing for antibody response
(5) molecular panels for respiratory pathogens
Respiratory specimens for Gram stain and culture may include:
(1) an adequate deep sputum specimen
(2) the patient has undergone bronchoscopy and a specimen free of oral contaminants can be obtained
(3) tracheal aspirate collected at the time of endotracheal tube placement
(4) percutaneous lung aspirate
(5) open lung biopsy
A respiratory specimen may be submitted for bacterial, fungal, mycobacterial and viral culture.
Urinary antigen tests can give false positive and false negative results, limiting their usefulness.
Serologic tests can be helpful in diagnosis of some infections but the results may be delayed.
Molecular panels can detect many respiratory pathogens rapidly but can be expensive. Advantages may include:
(1) reduced use of antibiotics if a viral pathogen is identified
(2) decreased need for bronchoscopy to make a diagnosis.
(3) identification of atypical bacteria (Mycoplasma pneumoniae, Chlamydia pneumoniae) which can help in antibiotic selection
