Table 3.
Microbial causes of CAP in childhood, according to age in descending order of frequency, and associated testing
| Age Grouping, Cause | Associated Testing33, 81, 82 |
|---|---|
| Birth–20 d | |
| Group B streptococci | Blood cultures should not be routinely performed in fully immunized, nontoxic children in outpatient setting, but should be obtained if children fail to improve or have progressive symptoms or clinically deteriorate after starting antibiotic therapy; blood and pleural fluid culture are insensitive, but there are no established alternatives in children |
| Gram-negative enteric bacteria | |
| Listeria monocytogenes | |
| 3 wk–3 mo | |
| Chlamydia trachomatis | Quadrupling of acute and convalescent serology, NP culture or NP PCR; although IDSA does not recommend diagnostic testing, because reliable and readily available diagnostic tests do not exist |
| RSV | NP swab for PCR or immunofluorescence, viral culture and DFA staining, acute and convalescent serology. Whereas influenza and RSV have winter-spring seasonality, PIV3 is present year-round |
| PIV 3 | |
| Streptococcus pneumoniae | Blood culture (yield <10%), urinary antigen (low specificity, many false-positives because of NP carriage), pneumolysin-based PCR of blood, pleural fluid and secretions |
| Bordetella pertussis | Culture, immunofluorescence assay, PCR assay of NP secretions |
| Staphylococcus aureus | Blood culture, pleural fluid culture |
| 4 mo–4 y | |
| RSV, parainfluenza viruses, influenza virus, adenovirus, rhinovirus | NP swab for PCR or immunofluorescence, viral culture and DFA staining, acute and convalescent serology |
| Streptococcus pneumoniae | Blood culture (yield <10%), urinary antigen (low specificity, many false-positive results because of NP carriage), pneumolysin-based PCR of blood, pleural fluid and secretions |
| Haemophilus influenzae | Blood culture, pleural fluid culture |
| Mycoplasma pneumoniae | Quadrupling of acute and convalescent serology is diagnostic, IgM antibody in acute or early convalescent serum is helpful, throat or NP swab PCR (high specificity and positive predictive value) |
| Mycobacterium tuberculosis | Identify bacteria in culture of sputum or gastric aspirates, with positive tuberculin skin test or interferon γ release assay |
| 5–15 y | |
| Mycoplasma pneumoniae | Quadrupling of acute and convalescent serology is diagnostic, IgM antibody in acute or early convalescent serum is helpful, throat or NP swab PCR (high specificity and positive predictive value) |
| Chlamydia pneumoniae | Quadrupling of acute and convalescent serology, NP culture or NP PCR; although IDSA does not recommend diagnostic testing, because reliable and readily available diagnostic tests do not exist |
| Streptococcus pneumoniae | Blood culture (yield <10%), urinary antigen (low specificity, many false-positive results because of NP carriage), pneumolysin-based PCR of blood, pleural fluid, and secretions |
| Influenza A or B, adenovirus | NP swab for PCR or immunofluorescence, viral culture and DFA staining, acute and convalescent serology |
| Nontypeable Haemophilus influenzae | Blood culture, pleural fluid culture |
| Mycobacterium tuberculosis | Identify bacteria in culture of sputum or gastric aspirates, with positive tuberculin skin test or interferon γ release assay |
| All ages, severe pneumonia requiring admission to intensive care unit: | |
| Streptococcus pneumoniae, Staphylococcus aureus, group A streptococci, Haemophilus influenzae type b, Mycoplasma pneumoniae, adenovirus | |
| Uncommon causes of pediatric CAP: | |
| Viruses: varicella zoster virus, coronaviruses, enteroviruses (coxsackievirus and echovirus), cytomegalovirus, Epstein-Barr virus, mumps virus, herpes simplex virus (in newborns), bocaviruses, polyomaviruses, measles virus, hantavirus | Varicella zoster virus: quadrupling of acute and convalescent serology, immunofluorescent assay of skin secretions; cytomegalovirus, Epstein-Barr virus: quadrupling of acute and convalescent serology, IgM antibody in acute serum; measles virus: quadrupling of acute and convalescent serology, immunofluorescent assay of NP secretions; hantavirus: quadrupling of acute and convalescent serology, IgM antibody in acute serum NP secretions or antibody in serum; sufficiently uncommon that IgM or IgG antibody in serum is essentially diagnostic |
| Chlamydia: Chlamydia psittaci | Quadrupling of acute and convalescent serology is diagnostic |
| Coxiella: Coxiella burnetii | Quadrupling of acute and convalescent serology is diagnostic |
| Bacteria: Streptococcus pyogenes, anaerobic mouth flora (Streptococcus milleri, Peptostreptococcus), nontype B (but typeable) Haemophilus influenzae, Bordetella pertussis, Klebsiella pneumoniae, Escherichia coli, Listeria monocytogenes, Neisseria meningitides (often group Y), Legionella, Burkholderia pseudomallei, Francisella tularensis, Brucella abortus, Leptospira | Francisella tularensis: quadrupling of acute and convalescent serology is diagnostic (blood or sputum culture requires special medium and may pose danger of infection to laboratory workers and they should be notified before handling specimen); Legionella pneumophila and other Legionella species: sputum or tracheal aspirate culture, urinary antigen (urinary antigen tests detect only Legionella pneumophila antigen); Brucella abortus: blood culture, quadrupling of acute and convalescent serology |
| Fungi: Coccidioides immitis, Histoplasma capsulatum, Blastomyces dermatitidis | Urinary Histoplasma or Blastomyces antigen, stain or culture of respiratory tract secretions, serum IgM antibody; quadrupling of acute and convalescent serology |
Abbreviations: DFA, direct fluorescent antibody; IDSA, Infectious Diseases Society of America; NP, nasopharyngeal; PCR, polymerase chain reaction.