Cause:Streptococcus pneumoniae,esp types 3, 6, 9A (most virulent)

Pathophys:(Nejm 1995;332:1280) Invasive w pyogenic response; little toxin production; pathogenic via numbers alone; polysaccharide capsule in virulent strains makes phagocytosis hard

Population carriers disseminate to pts w diminished resistance; 50% of population carries in upper respiratory tract at some time

Increased incidence in blood group A types because pneumococcus has A-like antigens, and in pts after splenectomy because residual RES requires increased antibody coating before phagocytosis can occur (Nejm 1981;304:245)

Vaccine (PCV7, see below) has led to decrease in rates of meningitis in kids; recent increase in meningitis and antibiotic resistance in non-PCV7 strains (NEJM 2009;360:244)

Sx:

Meningitis: Fever, confusion

Otitis media: Ear pain

Pneumonia: Fever, chills, sudden onset of pleurisy

Si:

Meningitis: Fever, confusion

Otitis media: Hot ear

Pneumonia: Bloody sputum unlike viral or mycoplasma

Pneumonia: Xray clears in 6 wk (Nejm 1970;283:798)

Meningitis: 50% mortality

Triad w endocarditis, meningitis, and pneumonia often fatal (Am J Med 1963;33:262); empyema

r/o multiple myeloma if crit low

Lab:Bact:Gram-pos diplococci; culture shows optochin-sensitive/bile salt soluble colonies

Rx:

Prevent w vaccine, which is inducing a declining rate of invasive disease in all ages including HIV pos children (Jama 2006;295:1668; Nejm 2003;348:1737, 1747; 2003;349:1341)

• Adult pneumococcal 23-valent vaccine (Pneumovax—Med Let 1999;41:84), 65% overall effective (Nejm 1991;325:1453; Ann IM 1988;108:653) at least for elderly (>65 yr) and people at increased risk, eg, splenectomy, COPD, alcoholics, diabetes, chronic renal pts on dialysis, CHF; in all patients? (Ann IM 1986;104:106 vs Jama 1996;275:194); ineffective in many sick pts who need it the most, eg, VA COPD pts (Nejm 1986;315:1318). Revaccinate if vaccination in doubt or once 5 yr later at least for high-risk pts and those who got 1st dose under age 65 yr (Mmwr 1997;46:1); local reactions in ~10% of those revaccinated (Jama 1999;281:243)
• Pediatric conjugated vaccine Prevnar: protects against 7 serotypes; or Synflorix: Prevnar types plus 3 additional serotypes (Jama 2000;283:1460) at 2, 4, 6, and 12 mos, or single dose thereafter; even single dose dramatically decreases pneumococcal infection rates under age 5 yr (Jama 2004;291:2197) including otitis media by 20+% (NNT-2 = 5) (Nejm 2001;344:403)

of disease: Since penicillin resistance now is so widespread though regionally variable, 25% nationally (Nejm 2000;343:1917), until know sensitivities, rx w ceftriaxone + vancomycin for life-threatening infections like meningitis; or vancomycin iv w po levofloxacin 500 mg po qd × 7-14 d, or 3rd-generation fluoroquinolone or telithromycin. Then, if sensitive, switch to penicillin or another ß-lactam antibiotic, though quinolone resistance appearing and can even develop during the crs of rx (Nejm 2002;346:747)