ABSTRACT
An 11 month-old infant had meningitis caused by a strain of Streptococcus pneumoniae, serotype 6b, resistant to penicillin, chloramphenicol, and several other antimicrobials. The minimum inhibitory concentrations (MIC) by agar dilution were 1.0 microgram/ml for penicillin and 16 microgram/ml for chloramphenicol. The infant did not respond to high-dose intravenous penicillin G but was cured by a combination of ampicillin, chloramphenicol, and rifampicin. At the infant's day-care centre this multiply resistant strain was isolated from throat cultures of 27% of the children (age less than or equal to 26 months) assigned to the same room as the index case, and from 11% of older children and staff. There was a 33% carriage rate in family contacts of colonised children. Antibiotic use during the previous 2 months was more frequent among the carriers than among non-carriers. No resistant pneumococci were found in on hundred and twenty-five children and staff in six other Denver day-care centres, in 300 consecutive routine throat cultures processed by our clinical microbiology laboratory, or among 150 pneumococcal isolates collected from Denver area hospitals. The carriers were not treated, and there have been no other cases of infection due to this strain. The emergence of multiply resistant pneumococci in the United States indicates the need to screen important pneumococcal isolates for resistance to both penicillin and chloramphenicol, especially in cases of meningitis.
