A significant increase in antimicrobial resistance among pneumococci causing invasive disease in New Zealand

Aims. To review the prevalence of antibiotic resistance and the distributio n of capsular types among pneumococci from invasive disease in New Zealand from 1995 through 1997. Method. Pneumococci isolated from sterile sites that were referred to the I nstitute of Environmental Science and Research (ESR) were tested for antimi crobial susceptibility and capsular type. Results. A total of 994 pneumococci were referred by 27 hospital and commun ity laboratories. Almost 74% of the isolates were from patients aged < 15 y ears or greater than or equal to 60 years. The majority (88.2%) of the isol ates were from blood cultures. In 1997, cefotaxime-resistant pneumococci we re confirmed for the first time from invasive disease in New Zealand. Over the three years, 6.0% of the pneumococci were penicillin-nonsusceptible (MI C greater than or equal to 0.12 mg/L) and 3.7% were cefotaxime-nonsusceptib le (MIC greater than or equal to 1 mg/L). Penicillin nonsusceptibility incr eased significantly from 1.9% in 1995 to 6.2% in 1996 and 9.9% in 1997. Sim ilarly, cefotaxime nonsusceptibility increased from 0.6% in 1995 to 3.5% in 1996 and 6.9% in 1997. In descending order of frequency, the ten most comm on capsular types were 14, 19, 6, 9, 1, 4, 18, 7, 23, and 3. Eighty-three p ercent of the penicillin-nonsusceptible pneumococci belonged to serotypes 9 V, 19A, 19F, 23F, 14 and 6B and 90% belonged to serotypes included in the 2 3-valent vaccine. Conclusions. The increasing prevalence of antimicrobial resistance among pn eumococci highlights the need for continued surveillance and for effective measures to prevent pneumococcal infections.