Susceptibility to antimicrobial agents in isolates from invasive Streptococcus pneumoniae in Colombia]

A study was done to determine the patterns of susceptibility to antimicrobial agents in isolates of Streptococcus pneumoniae that caused invasive disease diagnosed in children under the age of 5 in Colombia between 1994 and 1996, as well as to establish the distribution of the capsular types of the resistant isolates. The analysis was done using 324 isolates obtained during the performance of the National Serotyping Protocol for S. pneumoniae carried out in Bogotá, Medellín, and Cali, Colombia, between July 1994 and March 1996. Of the 324 isolates, 119 (36.7%) showed diminished susceptibility to at least one antimicrobial agent, including 39 (12%) that showed diminished susceptibility to penicillin. Of these 39 resistant to penicillin, 29 showed intermediate resistance and 10 showed high resistance. Nine isolates (2.8%) showed resistance to ceftriaxone, 80 (24.7%) to the combination of trimethoprim and sulfamethoxazole (TMS), 49 (15.1%) to chloramphenicol, and 31 (9.6%) to erythromycin. Resistance to two antimicrobial agents was observed in 31 isolates (9.6%); multiple resistance was found in 22 (6.7%). These 22 multiresistant isolates all showed resistance to TMS. The most frequent associations were penicillin, TMS, and erythromycin (5 cases); penicillin, chloramphenicol, TMS, and erythromycin (4 cases); penicillin, ceftriaxone, chloramphenicol, and TMS (3 cases); and penicillin, ceftriaxone, chloramphenicol, TMS, and erythromycin (3 cases). The most frequent serotypes in the penicillin-resistant isolates were: 23F (53.8%), 14 (25.6%), 6B (7.7%), 9V (5.1%), 19F (5.1%), and 34 (2.6%). The most frequent serotypes in the isolates resistant to antimicrobial agents other than penicillin were: 5 (37.5%), 23F (7.5%), 14 (18.8%), and 6B (13.8%). This difference in the distribution of the serotypes was statistically significant (P < 0.0001). The study results indicate the need to maintain active surveillance of antibiotic susceptibility patterns in order to avoid resistance in S. pneumoniae and to provide timely information to change practices regarding prescribing and consuming antimicrobial agents.