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Pneumococci causing invasive disease in New Zealand, 1987-94: serogroup and serotype coverage and antibiotic
1ESR:Health Communicable Disease Centre, Porirua.
Insights
Understanding pneumococcal serotypes and antibiotic resistance is crucial for developing effective vaccines. This study analyzed invasive pneumococcal disease in New Zealand, identifying common serotypes and resistance patterns in children and adults.
Area of Science:
- Microbiology
- Vaccinology
- Epidemiology
Background:
- The 23-valent pneumococcal vaccine shows limited efficacy in young children, necessitating research into alternative vaccine strategies.
- Understanding the global distribution of pneumococcal serotypes causing invasive disease is essential for vaccine development.
Purpose of the Study:
- To review the capsular serogroups and serotypes of Streptococcus pneumoniae causing invasive disease in New Zealand between 1987 and 1994.
- To analyze the antibiotic resistance patterns of these pneumococcal isolates.
Main Methods:
- Serogrouping and serotyping of pneumococcal isolates using the Neufeld test and Danish nomenclature.
- Antibiotic susceptibility testing performed via agar dilution method according to NCCLS guidelines.
Main Results:
- 1506 pneumococcal isolates were analyzed, with 39.8% from children (<15 years) and 39% from adults (≥60 years).
- Serogroups/serotypes 14, 19, 6, 9, 23, 7, 4, and 1 were common across age groups.
- Serogroups 6 and 18 were significantly associated with children, while serotype 3 was linked to adults. Penicillin resistance was found in 1.4% of isolates, with 14% resistant to at least one antibiotic.
Conclusions:
- The identified pneumococcal serotypes and antibiotic resistance patterns in New Zealand align with international findings.
- Continuous surveillance of antibiotic resistances and serotypes causing invasive pneumococcal disease is recommended.
Aims:
Development of polysaccharide-conjugated pneumococcal vaccines, prompted by the ineffectiveness of the current 23-valent vaccine for young children, requires an understanding of the pneumococci causing invasive disease worldwide. We have reviewed the capsular serogroups and serotypes, and the antibiotic resistances of pneumococci identified from invasive disease in New Zealand, for the period 1987-94.
Methods:
Pneumococci referred from invasive disease were serogrouped and serotyped using the Neufeld test and allocated a capsular type according to the Danish system of nomenclature. Antibiotic susceptibility testing was performed by an agar dilution method following National Committee for Clinical Laboratory Standards (NCCLS) guidelines.
Results:
A total of 1506 pneumococci were examined of which, 584 (39.8%) were sourced from children less than 15 years and 573 (39%) were from adults 60 years or greater. The majority (88.3%) were from blood cultures. In descending order of frequency serogroups or serotypes 14, 19, 6, 9, 23, 7, 4 and 1 were common to all age-groups but serogroups 6 and 18 were significantly (p < 0.001) associated with children under 15 years and serotype 3 with adult patients. Penicillin resistance was demonstrated by 22 (1.4%) isolates, five of which showed high level resistance (MIC > or = 2 mg/L) and multidrug resistance. Fourteen percent of all isolates were resistant to at least one antibiotic and serogroups 23, 6, 18, 19 and serotype 14 accounted for 82.6% of these resistant isolates.
Conclusions:
The serogroups and serotypes found most frequently associated with pneumococcal disease, and antibiotic resistance, were consistent with those described overseas. Continuing surveillance of antibiotic resistances and serotypes of pneumococci causing invasive disease is recommended.