Chloramphenicol and penicillin resistance in pneumococci isolated from blood and cerebrospinal fluid: a prevalence study in metropolitan Denver.

From January through October 1981, we screened blood and cerebrospinal fluid pneumococcal isolates from 101 patients in the Denver, Colorado area. Isolates from seven patients (6.9%) showed relative resistance to penicillin, with minimal inhibitory concentrations ranging from 0.12 to 1.0 microgram/ml. Two isolates (2.0%) were resistant to chloramphenicol, both with a minimal inhibitory concentration of 16 micrograms/ml. One of these was multiply resistant (to penicillin, chloramphenicol, and tetracycline). All isolates were susceptible to erythromycin, sulfamethoxazole-trimethoprim, and rifampin. On the basis of penicillin susceptibilities performed by participating hospitals on the isolates from 215 patients in the Denver area (101 included in the survey, 114 not included), we estimated the rate of relative resistance to penicillin to be approximately 4.3%. Compared with resistance rates reported in a previous study in Denver, these penicillin and chloramphenicol resistance rates may represent a trend of increasing resistance to these antibiotics in the Denver area. We recommend screening all isolates from invasive pneumococcal infections for penicillin and chloramphenicol susceptibility.