The safety, immunogenicity, and impact on carriage of a nonvalent pneumococcal vaccine given at ages 6, 10, and 14 weeks were examined in a double-blind, randomized, placebo-controlled trial in 500 infants in Soweto, South Africa. No serious local or systemic side effects were recorded. Significant antibody responses to all pneumococcal serotypes were observed 4 weeks after the third dose. Haemophilus influenzae type b polyribosylribitol phosphate (geometric mean titer, 11.62 microg/mL) and diphtheria (1.39 IU/mL) antibodies were significantly higher in children receiving pneumococcal conjugate, compared with placebo recipients (4.58 microgram/mL and 0.98 IU/mL, respectively). Nasopharyngeal carriage of vaccine serotypes decreased in vaccinees at age 9 months (18% vs. 36%), whereas carriage of nonvaccine serotypes increased (36% vs. 25%). Carriage of penicillin-resistant pneumococci (21% vs. 41%) and cotrimoxazole-resistant pneumococci (23% vs. 35%) were significantly reduced 9 months after vaccination, compared with controls.

No abstract

In children with invasive pneumococcal disease caused by the pediatric serogroups, HIV-infected children have more antibiotic-resistant isolates and have a different clinical presentation than do HIV-uninfected children.

Resistance to penicillin among South African strains of Streptococcus pneumoniae increased from 4.9% in 1979 to 14.4% in 1990. Except for resistance to co-trimoxazole (44%), resistance to other antimicrobial agents remained relatively low. Multiply resistant strains belonged mainly to serovars 6B, 19A, 14, and, more recently, 23F. Use of chloramphenicol to treat meningitis caused by strains relatively resistant to penicillin proved to be unsatisfactory, probably because of the inadequate bactericidal activity of chloramphenicol against these strains. Spread of penicillin-resistant nasopharyngeal strains in pediatric wards was most common among children who received antimicrobial therapy. Penicillin-binding protein (PBP) patterns were shown to vary in resistant clinical strains. Interspecies transfer of penicillin resistance between Streptococcus mitis and S. pneumoniae was demonstrated and antigenic homology was found in PBPs 1A and 2B of strains belonging to these species. Restriction enzyme mapping following DNA amplification of the PBP 2B gene revealed six arrangements among South African strains within serogroup 19. Despite extensive studies in South Africa and several other countries, many questions with regard to the global problem of antimicrobial resistance among S. pneumoniae strains remain unanswered, especially those that relate to prevalence in developing regions of the world.