Antibiotic susceptibility of Streptococcus pneumoniae in New Zealand

Aims. To determine the current antibiotic susceptibility patterns of Strept ococcus pneumoniae from four centres in New Zealand. Methods. Over a six-month period in 1997, 386 consecutive clinical isolates of S pneumoniae were collected by four laboratories (Auckland, Wellington, Hamilton and Christchurch) from general practice or inpatients. Susceptibi lity testing for seven antibiotics was performed by each centre using the E test. Results. Eighty-three-percent of isolates were penicillin susceptible, 12% showed intermediate resistance to penicillin and 5% were penicillin resista nt. Overall, 93 and 91% of isolates were susceptible to amoxicillin/clavula nic acid and ceftriaxone, respectively. Erythromycin and tetracycline had s imilar rates of susceptibility (88 and 87%, respectively). Resistance to co trimoxazole was common, with only 57% of isolates susceptible to this combi nation. No National Committee for Clinical Laboratory Standard (NCCLS) brea kpoints were available for cefaclor to allow interpretation of the minimum inhibitory concentration data for this agent. Wellington had lower resistan ce rates than Auckland, Christchurch and Hamilton. Isolates from children h ad. consistently higher resistance rates (two- to five-fold greater for bet a-lactams and 1.2 to 1.3-fold for other agents) compared with isolates from adult patients. Conclusions. Resistance to multiple antibiotics among S pneumoniae is now e vident in New Zealand, although rates varied between study centres. The ove rall rate of penicillin resistance is 5%, which is similar to that observed in many European and US cities but lower than the rates reported in badly affected areas (> 30%). These data suggest that amoxicillin (+/- clavulanic acid), erythromycin or tetracycline are appropriate agents for empirical u se in less serious community acquired infections when S pneumoniae is suspe cted. Ceftriaxone, with or without vancomycin, should be considered in the empirical treatment of invasive, disease until sensitivities are known.