Source: Tan TQ, et al. Clinical characteristics and outcome of children with pneumonia attributable to penicillin-susceptible and penicillin-nonsusceptible Streptococcus pneumoniae. Pediatrics 1998;102:1369-1375.
In this study, the "united states pediatric multicenter Pneumococcal Surveillance Study Group" reported on the clinical characteristics, treatment, and outcome of pediatric patients with pneumonia caused by penicillin susceptible and penicillin-nonsusceptible Streptococcus pneumoniae. Eight pediatric hospitals from around the country prospectively identified 254 patients with pneumococcal pneumonia between September 1993 and August 1996. Pneumococcal pneumonia was diagnosed based on chest x-ray findings and a positive blood or pleural fluid culture. Of the 254 patients, 189 (74%) were hospitalized. The hospitalized patients were more likely to have underlying illnesses, multiple lobe involvement, and pleural effusions.
Of the 257 S. pneumoniae isolates, 14% were nonsusceptible to penicillin (8% intermediately resistant and 6% resistant), and 5% were nonsusceptible to cefriaxone. There were no significant differences for duration of fever, oxygen requirement, WBC count, underlying disease, x-ray findings, or hospitalization rates between the penicillin-susceptible and penicillin-nonsusceptible groups.
There was also no significant difference in outcome between the penicillin-susceptible and penicillin-nonsusceptible groups. Ninety-eight percent of the 254 patients had a good response to therapy. All six children with poor outcomes had underlying illnesses (1 had a penicillin-resistant isolate).
Comment by Leonard Friedland, MD
Previous reviews in Emergency Medicine Alert have commented on the increasing prevalence of isolates of S. pneumoniae that are resistant to penicillin and other antibiotics. This may affect our current treatment of common bacterial diseases caused by S. pneumoniae, such as otitis media and community acquired pneumonia. In this recent study from sites throughout the United States, clinical characteristics and patient outcome did not differ between children with pneumonia attributable to penicillin-susceptible and penicillin-nonsusceptible S. pneumoniae.
What antibiotic regimen should be used for the treatment of infections caused by penicillin-resistant S. pneumoniae? The specific doses of antimicrobial agents used in study patients are not presented. However, we are told that in the group treated as outpatients, 80% received a dose of parenteral second- or third-generation cephalosporin followed by a course of oral antibiotic, 17% were treated with oral beta-lactam antibiotic alone, and 3% with oral nonbeta-lactam antibiotic alone. In the group hospitalized, 48% received a dose of parenteral second- or third-generation cephalosporin followed by a course of oral antibiotic. All the children without underlying illnesses responded well to what appears to be standard antimicrobial therapy.
Information I have gleaned from the literature and attending conferences indicates that standard doses of amoxicillin, amoxicillin with clavulinic acid, and cephalosporins can exceed the MIC of resistant strains of S. pneumoniae. Despite this, many infectious disease experts now recommend that high doses of oral antibiotics be used to treat S. pneumoniae infections (e.g., treating an episode of acute otitis media with 80 mg/kg/d of amoxicillin). The rationale behind this recommendation is to clearly exceed the MIC of the resistant strain. I expect to report again on this topic as the prevalence of S. pneumoniae antibiotic resistance continues to increase.
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