Nejm 2002;346:430—children; 1995;333:1618

Cause:

<1 month, commonly: group B strep, E. coli,and other gram negatives, CMV
less commonly: S. aureus,RSV, Enterobactersp, Listeria

1 mo to 5 yr, commonly: RSV, parainfluenza virus, adenovirus, rhinovirus, influenza
less commonly: Strep pneumoniae, chlamydia, whooping cough, Staph, mycoplasma, H. flu, tbc

5-15 yr, commonly: influenza A, adenovirus, chlamydia
less commonly: Mycoplasma, Strep pneumoniae,tbc

Adults (%’s from Nejm above): Strep. pneumoniae(50%), viral including influenza A (10%), aspiration (8%), H. flu (6%; others feel much higher, up to 30%, depending on group), Staph aureus(4%), gram negatives (6%), atypicals (15%) including mycoplasma (4%) and Chlamydia(5%), which are higher (>20%) in young adults, and Legionella(5%)
in elderly, prognosis bad if elevated BUN, hypotensive, respiratory rate >30 (Ann IM 1991;115:428)

Much more common in immunosuppressed pts who constitute 60% of hospital admissions for pneumonia

Sx:Cough, fever, dyspnea, sputum production, pleurisy

Si:T° (80%); RR >20 in adults; RR >40 age 1-5 yr, >50 age 2-12 mo, >60 under 2 mo, in children, 70% sens and specif (Arch Dis Child 2000;82:41, 46); rales (80%), consolidation changes (30%), bronchial breath sounds, dullness, E to A changes

Empyema

Lab:

ABGs:admit if pO₂ below 60; procalcitonin level over 0.25 µg/L makes bacterial cause more likely, decr. unnecessary abx use (Jama 2009;302:1059, 1115)

Bact:Blood cultures (pos in 11% overall, in 67% w S. pneumoniae), sputum Gram stain (50% pos inS. pneumoniae)

Chem:Procalcitonin level >0.25 µg/L makes bacterial cause much more likely (Jama 2009;302:1059, 1115)

Hem:CBC

Xray:Chest, infiltrate, although false negs esp in 1st 24 h or w neutropenia or w PCP (10-30% neg); effusions (40%). Resolution in community-acquired in elderly takes 12-14 wk (Jags 2004;52:224)

Rx: (Jama 2006;295:2503—NH rx; Nejm 2002;347:2039 for hospitalization criteria; Med Let 2007;49:62)

Outpts: azithromycin; or 2nd, tetracycline at least under age 60 yr w/o complicating illness (Jama 1997;278:32); or a 3rd-generation fluoroquinolone alone w good antipneumococccal activity like levofloxacin, moxifloxacin, or gatifloxacin, esp if age >60 yr

Inpts, get antibiotics started w/i 4 h for best outcomes: 3rd-generation cephalosporin like ceftriaxone or cefotaxime w a macrolide; or a 3rd-generation fluoroquinolone

ICU pts: imipenem + aminoglycoside if Pseudomonaspossible (Med Let 1996;38:25); linezolid or vancomycin for MRSA coverage

Aspiration (Nejm 2001;344:665): levofloxacin 500 mg qd, or ceftriaxone 1-2 gm qd

if bad teeth, consider anaerobes and rx w clindamycin as well