Vaccine coverage of Streptococcus pneumoniae in Hong Kong with attention to the multiple-antibiotic-resistant strains.

Two hundred and four isolates of Streptococcus pneumoniae obtained from children and adults in Hong Kong between January 1993 and May 1995 were analysed for serotype and serogroup (SGT) distribution and antibiotic resistance. The predominant serogroups and serotypes (SGTs) were 23, 19, 6 and 3 which accounted for 19.6%, 16.7%, 15.2% and 7.8% of all isolates, respectively. Altogether, 83.8% of all isolates were related to the current 23-valent pneumococcal vaccine. Sixty-six (32.4%) isolates demonstrated multiple antibiotic resistance, defined as resistance to three or more different antibiotics. SGTs 19, 23 and 6 occurred significantly more frequently in this group than in the groups with less antibiotic resistance (97% vs 30%; P < 0.001). Isolates shown to be resistant to all five antibiotics tested (penicillin, chloramphenicol, ceftriaxone, macrolides and tetracycline) were found only in serogroups 6, 19 and 23. The 23-valent vaccine should cover 84.4% (152/180) of SGTs with one or more antibiotic resistance in all age groups, while the proposed 9-valent global pneumococcal conjugate vaccine should cover 85.0% (34/40) of such SGTs in children.