Pneumonia caused by a relatively resistant strain of Streptococcus pneumoniae

A patient with pneumonia caused by a relatively resistant strain of Streptococcus pneumoniae that did not respond to prolonged therapy with intravenous ampicillin is described, and general principles of treatment for such cases are reviewed. The patient was a 16-month-old, 10-kg girl who was admitted to a hospital for treatment of severe smoke inhalation and burns. The patient was intubated immediately, but her respiratory status remained unstable. Chest roentgenograms showed numerous episodes of pneumonia; the organism was later identified as Strep. pneumoniae. Despite empiric therapy with ampicillin and tobramycin followed by a prolonged course of ampicillin and subsequent treatment with cefazolin, the patient's respiratory status did not improve, and she continued to have elevated temperatures. Strep. pneumoniae isolated from her blood was identified as relatively resistant to penicillin but sensitive to chloramphenicol. After a seven-day course of chloramphenicol, the patient recovered and was later discharged. Relatively resistant Strep. pneumoniae (RRSP) infections often occur at sites where high antibiotic concentrations are not achieved, such as in the CNS. Prior antibiotic therapy may increase or have no effect on the incidence of RRSP. The mechanism for RRSP is unknown, and these infections often are not detected until a patient has failed to respond to conventional therapy. Also, the incidence of RRSP has not been determined because many hospitals do not perform susceptibility tests for pneumococcal isolates routinely. Vancomycin or chloramphenicol may be alternates to penicillin for the treatment of RRSP, but antibiotic sensitivities should be determined for each isolate to ensure susceptibility.