Streptococcus pneumoniae and community-acquired pneumonia: a cause for concern

Abstract

Community-acquired pneumonia (CAP) is the sixth most common cause of death in the United States and the leading cause of death from infectious diseases. It is associated with significant morbidity and mortality, and poses a major economic burden to the healthcare system. Streptococcus pneumoniae is the leading cause of CAP. Other common bacterial causes include Haemophilus influenzae as well as atypical bacteria (Mycoplasma pneumoniae, Chlamydia pneumoniae, and Legionella species). Increasing resistance to a variety of antimicrobial agents has been documented in S. pneumoniae and is common in H. influenzae as well. Successful empiric therapy is paramount to the management of CAP to avoid treatment failure and subsequent associated costs. Given that resistance is increasing among respiratory pathogens, and S. pneumoniae is the most common etiologic agent identified in CAP, strategies for antimicrobial therapy should be based on the likely causative pathogen, the presence of risk factors for infection with resistant bacteria, and local resistance patterns.

Figure 1

Age-specific rates of community-acquired pneumonia caused by specific pathogens. (Reprinted with permission from Arch Intern Med.⁴)

Figure 2

Trends in penicillin resistance among Streptococcus pneumoniae in the United States. *Number of centers contributing isolates. MIC = minimum inhibitory concentration. (Courtesy of G. V. Doern, personal communication, December 2002.)

Figure 3

Increasing Streptococcus pneumoniae resistance in response to increased use of penicillin. (Reprinted with permission from J Antimicrob Chemother.⁵⁵)

Figure 4

Outcomes for 192 hospitalized patients with pneumococcal pneumonia. *Statistically significant, unadjusted for other risk factors (when adjusted for other risk factors, the only outcome with significant differences was suppurative complications). ICU = intensive care unit; RR = unadjusted relative risk, Cochran-Mantel-Haenszel statistics. (Adapted from Clin Infect Dis.⁶²)