Strep Pneumoniae Infection

Learning Objectives:
Review Strep Pneumoniae
Discuss complications
Summarize treatment

Strep Pneumoniae Infection
Invasive pneumococcal infection is defined as the isolation of Streptococcus pneumoniae from a normally sterile site, such as the blood or cerebrospinal fluid
Risks: cigarette smoking, chronic obstructive pulmonary disease, alcohol abuse, neurologic disease, malignancy, liver disease, IV drug use, congestive heart failure, diabetes mellitus, HIV infection, recent hospitalization, winter, preceding viral infection.
Signs and Symptoms: fevers, night sweats, malaise are more common in the young
absence of fever with strep pneumo pna is a poor prognostic indicator as is hypothermia
Mandell's has the following comment, which is pertinent to our case:
"Patients with pneumococcal pneumonia usually appear ill and have a grayish, anxious appearance that differs from that of persons with viral or mycoplasmal pneumonia."
CXR usually reveals an infiltrate
Empyema and pleural effusions are rare as strep pneumo does not produce tissue toxins

Complications:
-Empyema, although rare, is among the most common complications occuring in 5% pre-antibiotic era and 2% now
Cardiac- series of 170 hospitalized veterans, cardiac complications were common and thought to be due to increased inflammation, dec o2 supply, and increased cardiac demand
19% had at least one major cardiac complication
including 7% with acute myocardial infarction
5% with new-onset atrial fibrillation or ventricular tachycardia
8% with newly diagnosed or worsening CHF
-Pneumococcal endocarditis is seen once every 10 yrs at most US hospitals. Most IE involves previously normal valves and is rapidly progressive; purulent pericarditis is extremely rare
- Pneumococcal peritonitis occurs by hematogenous or local inoculation (female reproductive tract or bowel perf) of the peritoneal cavity
-Pneumococcal infections may affect the female reproductive organs
-Septic arthritis may affect a prosthetic or arthritic joint; osteomyelitis may involve vertebral bones
-Epidural abscesses are rare
- Meningitis is estimated to occur in up to 4% of cases of invasive pneumococcus
-Soft tissue infections are more common in those with HIV infection

Treatment:
PCN resistance was first noted in the 70's, later MICs were used to determine resistance patterns
In 2008, MICs were assigned based on location of infection ie) lung vs CNS
In the US, 25% of pneumococci are resistant to macrolides
17% are resistant to pcn
10% are resistant to clindamycin
30% are resistant to trimethoprim-sulfamethoxazole
18% are resistant to doxycycline
2% are resistant to the newer quinolones
Beta-lactam antibiotics: penicillin, penicillin derivatives or second generation cephalosporins are recommended for PCN sensitive strains
No consensus on duration of therapy

Should all CAP patients get blood cultures?
New evidence (and push towards cost-effectiveness) suggests we should not order blood cultures on all patients with CAP.
Hi CRP and CXR Infiltrate are predicters of bacteremia amongst hospitalized patients with CAP
Check out the following study for more:
Analysis of blood cultures in patients presenting with community-acquired pneumonia at the emergency room].
Nagata K, Hirota T, Fujiwara H.



References:
Mandell: Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases, 7th ed. Pneumonia
Madjid M, Vela D, Khalili-Tabrizi H, et al: Systemic infections cause exaggerated local inflammation in atherosclerotic coronary arteries: Clues to the triggering effect of acute infections on acute coronary syndromes.  Tex Heart Inst J  2007; 34:11-18.
Uptodate: Pneumococcal pneumonia in adults

(Ellen Eaton MD, 11/30/10)