SUSCEPTIBILITY OF PNEUMOCOCCAL CARRIAGE ISOLATES TO PENICILLIN PROVIDES A CONSERVATIVE ESTIMATE OF SUSCEPTIBILITY OF INVASIVE PNEUMOCOCCI

Objective, Because of its practical importance for public health monit oring in developing countries, we aimed to determine whether susceptib ility to penicillin of pneumococci isolated from the upper respiratory tract (URT) is representative of the susceptibility of pneumococci ca using pneumonia in children, Method, The serogroup distribution and mi nimum inhibitory concentration of penicillin for 56 and 90 isolates fr om blood and cerebrospinal fluid, respectively, were compared with tho se of 833 pneumococcal carriage isolates from Papua New Guinean childr en. These included 154 and 98 strains from bacteremic and nonbacteremi c hospitalized patients with pneumonia, respectively, 350 from outpati ents with respiratory infections and 176 and 55, respectively, from ch ildren in a community based study who were healthy or sick with pneumo nia, Results, Proportions of pneumococci intermediately resistant to p enicillin were comparable in the URT and blood (60%) in 1985 through 1 987 when serogroup distributions in the two sites were similar. Howeve r, penicillin resistance was higher in the URT (75%) than blood (44%) in 1980 through 1984 when the less frequently carried, less resistant serogroups (1 to 5, 7 to 12, 45 and 46) accounted for a high proportio n of bacteremic strains. Conclusions, URT isolates from any group of s ick or healthy children could provide a conservative estimate of antim icrobial susceptibility of invasive strains and is a practical way of monitoring susceptibility as well as evaluating the continued effectiv eness of standard antibiotic therapy. If there was cause for concern, it would then be necessary to examine invasive isolates.