Community-acquired pneumonia: drug-resistant pneumococcal infections were common

Clinical bottom line (level 4)

  1. Many cases of pneumococcal pneumonia were found to be resistantto penicillins or cephalosporins.
  2. Immunocompetent patients aged 65 or more were at increased risk of having a cephalosporin-resistant pneumococcal pneumonia.
  3. Immunocompetent patients with 2 or more comorbidities were more likely to have a pencillin-resistant infection.
  4. Immunosuppressed patients with a bacteraemia were less likely to have a drug-resistant infection.
Ewig et al: American Journal of Respiration and Critical Care Medicine 1999; 159: 1835-1842
Expires March 2003

The study

Case-control study with objective outcomes, not adjusted for confounding factors, not validated in an independent set of patients.

Setting: teaching hospital, Germany

101 patients (aged immunocompetent: mean 67; immunosuppressed: mean 38), 72% male) with community-acquired pneumonia (diagnosed on chest X-ray) due to Streptococcus pneumoniae (confirmed on culture). 22% were immunosuppressed

Excluded if
  • pneumonia due to another infectious agent


    • Cases: 52 patients (-% male, mean age -): with drug-resistant infection
    Controls: 49 patients (-% male, mean age -): infection sensitive to cephalosporins or penicillin

    Factors studied:
  • co-morbidities, age, sex, hospitalisation within previous year, HIV infection, need for mechanicalventilation


    • Factors summarised:
  • immunosuppressed: bacteraemia
  • aged 65 or more
  • immunocompetent: 2 or more comorbidities
  • immunosuppressed: bacteraemia


    • Outcomes studied:
  • cephalosporin-resistant infection
  • penicillin-resistant infection

    • The evidence

    Patient expected event rate for cephalosporin-resistant infection: 28%
    risk factor for
    cephalosporin-resistant infection     		unadjusted OR
    (95% CI)    		 NNH
    (95% CI)
    immunosuppressed: bacteraemia 0.46
    (0.23 to 0.93)     		-8
    (-69 to -5)
    aged 65 or more 5.0
    (1.3 to 18.8)     		3
    (2 to 5)

    Patient expected event rate for penicillin-resistant infection: 38%
    risk factor for
    penicillin-resistant infection     		unadjusted OR
    (95% CI)    		 NNH
    (95% CI)
    immunocompetent: 2 or more comorbidities 4.7
    (1.2 to 19.1)     		3
    (2 to 23)
    immunosuppressed: bacteraemia 0.04
    (0.003 to 0.45)     		-3
    (-6 to -3)

    Comments

    1. Drug resistance was not clearly associated with increased mortality.
    2. Prevalence of drug resistance has great geographical variation,but is an emerging, serious problem.
    3. Possibility of overestimate of problem if drug-resistant strainsare more easily isolated than drug-sensitive ones.

    Citation

    1. Ewig S, Ruiz M, Torres A, et al: pneumonia acquired in the community through drug-resistant Streptococcus pneumoniae. American Journal of Respiration and Critical Care Medicine 1999; 159: 1835-1842
    Search Terms: ?
    Contributor: Chris Ball and Clare Wotton, November 1999
    Reviewer: Mitsuhiro Kamei

    Clinical Question.
    Patient pneumococcal pneumonia
    Intervention or Exposure risk factors
    Outcome penicillin or cephalosporin resistant infection