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Emergence of antibiotic-resistant pneumococcal serotypes causing invasive pneumococcal disease in children, Spain
Joaquín Llorente1,2,3, Julio Sempere1,4, Mirella Llamosí1,4
1Spanish Pneumococcal Reference Laboratory, National Center for Microbiology, Instituto de Salud Carlos III, Madrid, Spain.
Insights
Pneumococcal conjugate vaccines (PCVs) reduced invasive pneumococcal disease (IPD) in children. However, antibiotic-resistant strains, particularly non-PCV13 serotypes like 24F, are increasing, posing a new challenge.
Area of Science:
- Microbiology
- Epidemiology
- Vaccinology
Background:
- Pneumococcal conjugate vaccines (PCVs) have decreased invasive pneumococcal disease (IPD) globally.
- The emergence of non-vaccine serotypes with reduced antibiotic susceptibility is a concern.
- Surveillance of antibiotic resistance patterns is crucial for public health.
Purpose of the Study:
- To analyze changes in antibiotic-resistant *Streptococcus pneumoniae* strains causing IPD in children.
- To evaluate the impact of PCV13 and the COVID-19 pandemic on antibiotic resistance.
- To identify prevalent non-vaccine serotypes contributing to IPD-RS.
Main Methods:
- National surveillance of 4,455 pediatric IPD isolates in Spain (2009-2023).
- Analysis of antibiotic susceptibility to penicillin and erythromycin.
- Stratification of data into six periods: pre-PCV13, early, middle, late PCV13, COVID-19, and reopening.
Main Results:
- Overall IPD cases decreased significantly (over 60% in 1-4 years, 50% in <1 year).
- Increased incidence of IPD-RS caused by non-PCV13 serotypes, with 24F being most prevalent.
- PCV13 introduction substantially reduced IPD; COVID-19 caused a temporary decline in resistant strains.
Conclusions:
- PCV13 effectively reduced IPD but led to an increase in non-PCV13 serotype resistance.
- Serotype 24F is a growing concern for antibiotic resistance in IPD.
- Pandemic measures temporarily lowered resistant strain burden, followed by recovery.
Abstract:
Pneumococcal conjugate vaccines (PCVs) have significantly reduced disease burden caused by Streptococcus pneumoniae, a leading cause of childhood morbidity and mortality globally. The rise of non-vaccine serotypes is a frequent phenomenon after the use of these PCVs. This study is a national surveillance that includes all pneumococcal isolates causing invasive pneumococcal disease (IPD) (4,455 isolates) in the pediatric population to analyze the changes of strains with reduced susceptibility (IPD-RS) to different antibiotics (1,458 to penicillin/1,304 to erythromycin) and the impact of PCVs and COVID-19 pandemic on antibiotic resistance. Six periods are differentiated according to this decline: pre-PCV13, early PCV13, middle PCV13, late PCV13, COVID-19, and reopening. Between 2009 and 2023, overall IPD cases in Spain decreased by over 60% in children aged 1-4 years and by approximately 50% in infants under 1 year of age. Nevertheless, an increase in IPD-RS caused by non-PCV13 serotypes was observed, with serotype 24F being the most prevalent, which is not included in the currently licensed PCVs. The introduction of PCV13 showed a substantial impact on reducing IPD in children. The COVID-19 pandemic led to a temporary decline in the burden of disease caused by resistant strains in 2020 due to non-pharmacological measures followed by a subsequent recovery.
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