Peer-reviewed article
Characteristics of Streptococcus pneumoniae colonising Cypriot children during a period of high PCV10 and PCV13 vaccine coverage: serotypes and antimicrobial resistance.
Gavriella Ioannou Vassiliadou, Petros Ladas, Michail Mendris, Stella Mazeri, Maria Michail et al. ·
Summary
Written by AI, not yet AICS's view · claude-haiku-4-5-20251001This study examined nasopharyngeal carriage of Streptococcus pneumoniae in 809 Cypriot children aged 6 months to 6 years during 2023-2024, when vaccine coverage was high. Over one-third of children carried pneumococcal bacteria, mostly non-vaccine serotypes, and many isolates showed resistance to common antibiotics. Vaccination provided some protection against carriage, but most infections were not preventable by current vaccines, highlighting the need for continued surveillance.
Key points
- 35.72% of children carried Streptococcus pneumoniae nasopharyngeal bacteria despite 83.85% being fully vaccinated with pneumococcal conjugate vaccines
- 68% of isolates were not covered by available vaccines, with dominant non-vaccine serotypes being 15B, 23A, 23B, 24, 6C, and 15A
- Resistance to erythromycin (54.32%), tetracycline (37.28%), and clindamycin (31.65%) was common; 28.94% of isolates were multidrug-resistant
- Receipt of at least one vaccine dose was protective against carriage (OR 0.38), but recent antibiotic use and daycare attendance increased carriage risk
- The predominance of non-vaccine serotypes and high antimicrobial resistance indicate limitations of current vaccination strategies in Cyprus
Limitations
This was a cross-sectional study measuring carriage at one point in time, so it cannot establish causation or track how carriage patterns change over time. The study did not assess clinical outcomes (disease or invasive infections), only bacterial colonisation.
Abstract
BACKGROUND: Nasopharyngeal carriage of Streptococcus pneumoniae is a key factor for transmission, invasive disease, and antimicrobial resistance. Data on pneumococcal carriage in children in Cypriot are limited. METHODS: We conducted a cross sectional study from December 2023 to May 2024, during a period of high PCV10 and PCV13 vaccine coverage in Cyprus, including children aged six months to six years who attended outpatient clinics in Cyprus. Nasopharyngeal swabs were cultured, and Streptococcus pneumoniae isolates were identified using conventional methods and confirmed by polymerase chain reaction. Serotyping was performed using multiplex polymerase chain reaction, latex agglutination, and whole-genome sequencing when needed. Antimicrobial susceptibility was assessed according to European guidelines. Logistic regression was used to identify risk factors for carriage. RESULTS: A total of 809 children were included, 83.85% of whom were fully vaccinated with pneumococcal conjugate vaccines. The overall prevalence of carriage was 35.72%. Recent antibiotic use (OR 1.47, 95% CI 1.03-2.12) and daycare attendance (OR 1.89, 95% CI 1.37-2.63) were associated with increased carriage, whereas receipt of at least one vaccine dose was protective (OR 0.38, 95% CI 0.17-0.82). Among the 290 isolates, 34 distinct serotypes were identified, predominantly non-vaccine types including 15B, 23A, 23B, 24, 6C, and 15A. Most isolates (68%) were not covered by available vaccines. Resistance was highest for erythromycin (54.32%), tetracycline (37.28%), and clindamycin (31.65%). Multidrug resistance occurred in 28.94% of the isolates, mainly in serotypes 24, 15A, and 19A. CONCLUSIONS: Despite extensive vaccination, pneumococcal carriage in Cypriot children remains high, with predominance of non-vaccine serotypes and substantial antimicrobial resistance. Continuous surveillance is essential to guide vaccination and antimicrobial stewardship.