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Lux J, Sánchez García L, Chaparro Fernández P, Laloli L, Licheri MF, Gallay C, Hermans PWM, Croucher NJ, Veening JW, Dijkman R, Straume D, Hathaway LJ. AmiA and AliA peptide ligands, found in Klebsiella pneumoniae, are imported into pneumococci and alter the transcriptome. Sci Rep 2024; 14:12416. [PMID: 38816440 PMCID: PMC11139975 DOI: 10.1038/s41598-024-63217-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Accepted: 05/27/2024] [Indexed: 06/01/2024] Open
Abstract
Klebsiella pneumoniae releases the peptides AKTIKITQTR and FNEMQPIVDRQ, which bind the pneumococcal proteins AmiA and AliA respectively, two substrate-binding proteins of the ABC transporter Ami-AliA/AliB oligopeptide permease. Exposure to these peptides alters pneumococcal phenotypes such as growth. Using a mutant in which a permease domain of the transporter was disrupted, by growth analysis and epifluorescence microscopy, we confirmed peptide uptake via the Ami permease and intracellular location in the pneumococcus. By RNA-sequencing we found that the peptides modulated expression of genes involved in metabolism, as pathways affected were mostly associated with energy or synthesis and transport of amino acids. Both peptides downregulated expression of genes involved in branched-chain amino acid metabolism and the Ami permease; and upregulated fatty acid biosynthesis genes but differed in their regulation of genes involved in purine and pyrimidine biosynthesis. The transcriptomic changes are consistent with growth suppression by peptide treatment. The peptides inhibited growth of pneumococcal isolates of serotypes 3, 8, 9N, 12F and 19A, currently prevalent in Switzerland, and caused no detectable toxic effect to primary human airway epithelial cells. We conclude that pneumococci take up K. pneumoniae peptides from the environment via binding and transport through the Ami permease. This changes gene expression resulting in altered phenotypes, particularly reduced growth.
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Affiliation(s)
- Janine Lux
- Institute for Infectious Diseases, Faculty of Medicine, University of Bern, Friedbühlstrasse 25, CH-3001, Bern, Switzerland
- Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland
| | - Lucía Sánchez García
- Institute for Infectious Diseases, Faculty of Medicine, University of Bern, Friedbühlstrasse 25, CH-3001, Bern, Switzerland
| | - Patricia Chaparro Fernández
- Institute for Infectious Diseases, Faculty of Medicine, University of Bern, Friedbühlstrasse 25, CH-3001, Bern, Switzerland
| | - Laura Laloli
- Institute for Infectious Diseases, Faculty of Medicine, University of Bern, Friedbühlstrasse 25, CH-3001, Bern, Switzerland
| | - Manon F Licheri
- Institute for Infectious Diseases, Faculty of Medicine, University of Bern, Friedbühlstrasse 25, CH-3001, Bern, Switzerland
| | - Clement Gallay
- Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland
| | - Peter W M Hermans
- Julius Centre for Health Sciences and Primary Care, University Medical Centre Utrecht (UMCU), Utrecht, The Netherlands
| | - Nicholas J Croucher
- MRC Centre for Global Infectious Disease Analysis, White City Campus, Imperial College London, Sir Michael Uren Hub, London, UK
| | - Jan-Willem Veening
- Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland
| | - Ronald Dijkman
- Institute for Infectious Diseases, Faculty of Medicine, University of Bern, Friedbühlstrasse 25, CH-3001, Bern, Switzerland
- Multidisciplinary Center for Infectious Diseases, University of Bern, Bern, Switzerland
- Microscopy Imaging Centre (MIC), Theodor Kocher Institute, University of Bern, Bern, Switzerland
- European Virus Bioinformatics Center, Jena, Germany
| | - Daniel Straume
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, 1430, Ås, Norway
| | - Lucy J Hathaway
- Institute for Infectious Diseases, Faculty of Medicine, University of Bern, Friedbühlstrasse 25, CH-3001, Bern, Switzerland.
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Grant LR, Hanquet G, Sepúlveda-Pachón IT, Theilacker C, Baay M, Slack MPE, Jodar L, Gessner BD. Effects of PCV10 and PCV13 on pneumococcal serotype 6C disease, carriage, and antimicrobial resistance. Vaccine 2024; 42:2983-2993. [PMID: 38553292 DOI: 10.1016/j.vaccine.2024.03.065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2023] [Revised: 02/26/2024] [Accepted: 03/24/2024] [Indexed: 04/22/2024]
Abstract
BACKGROUND The cross-protection of pneumococcal conjugate vaccines (PCV) against serotype 6C is not clearly documented, although 6C represents a substantial burden of pneumococcal disease in recent years. A systematic review by the World Health Organization that covered studies through 2016 concluded that available data were insufficient to determine if either PCV10 (which contains serotype 6B but not 6A) or PCV13 (containing serotype 6A and 6B) conferred protection against 6C. METHODS We performed a systematic review of randomized controlled trials and observational studies published between January 2010 - August 2022 (Medline/Embase), covering the direct, indirect, and overall effect of PCV10 and PCV13 against 6C invasive pneumococcal disease (IPD), non-IPD, nasopharyngeal carriage (NPC), and antimicrobial resistance (AMR). RESULTS Of 2548 publications identified, 112 were included. Direct vaccine effectiveness against 6C IPD in children ranged between 70 and 85 % for ≥ 1 dose PCV13 (n = 3 studies), was 94 % in fully PCV13 vaccinated children (n = 2), and -14 % for ≥ 1 dose of PCV10 (n = 1). Compared to PCV7, PCV13 efficacy against 6C NPC in children was 66 % (n = 1). Serotype 6C IPD rates or NPC prevalence declined post-PCV13 in most studies in children (n = 5/6) and almost half of studies in adults (n = 5/11), while it increased post-PCV10 for IPD and non-IPD in all studies (n = 6/6). Changes in AMR prevalence were inconsistent. CONCLUSIONS In contrast to PCV10, PCV13 vaccination consistently protected against 6C IPD and NPC in children, and provided some level of indirect protection to adults, supporting that serotype 6A but not 6B provides cross-protection to 6C. Vaccine policy makers and regulators should consider the effects of serotype 6A-containing PCVs against serotype 6C disease in their decisions.
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Affiliation(s)
- Lindsay R Grant
- Medical Development and Scientific Clinical Affairs, Pfizer Vaccines, 500 Arcola Road, Collegeville, PA 19426, USA.
| | - Germaine Hanquet
- P95 Epidemiology & Pharmacovigilance, Koning Leopold III-laan 1, 3001 Leuven, Belgium.
| | | | - Christian Theilacker
- Medical Development and Scientific Clinical Affairs, Pfizer Pharma GmbH, Berlin, Germany.
| | - Marc Baay
- P95 Epidemiology & Pharmacovigilance, Koning Leopold III-laan 1, 3001 Leuven, Belgium.
| | - Mary P E Slack
- School of Medicine & Dentistry, Griffith University Gold Coast Campus, Parklands Drive, Southport, Queensland, QLD 4222, Australia.
| | - Luis Jodar
- Medical Development and Scientific Clinical Affairs, Pfizer Vaccines, 500 Arcola Road, Collegeville, PA 19426, USA.
| | - Bradford D Gessner
- Medical Development and Scientific Clinical Affairs, Pfizer Vaccines, 500 Arcola Road, Collegeville, PA 19426, USA.
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Warda K, Amari S, Boureddane M, Elkamouni Y, Arsalane L, Zouhair S, Bouskraoui M. Changes in pneumococcal serotypes distribution and penicillin resistance in healthy children five years after generalization of PCV10. Heliyon 2024; 10:e25741. [PMID: 38380016 PMCID: PMC10877248 DOI: 10.1016/j.heliyon.2024.e25741] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Revised: 01/11/2024] [Accepted: 02/01/2024] [Indexed: 02/22/2024] Open
Abstract
Objective Streptococcus pneumoniae (S. pneumoniae) nasopharyngeal carriage has significantly decreased after the generalization of pneumococcal vaccination worldwide. This study sought to investigate changes in S. pneumoniae carriage rates, serotype distribution and penicillin non-susceptibility following the generalization of 10-valent pneumococcal conjugate vaccine. Methods A prospective study was conducted in Marrakesh, Morocco, between 2017 and 2018, among healthy children attending vaccination centers. We collected nasopharyngeal swabs and questionnaire data for each child. Using univariate logistic regression, we analyzed the association between S. pneumoniae carriage and various risk factors. Comparisons of serotype diversity and penicillin resistance between 2017 and 2018 and the period before introduction of vaccination (2008-2009, n = 660) were performed using Simpson index and the chi-squared test, respectively. Results During 2017-2018, 515 children aged between 6 and 36 months participated. The S. pneumoniae carriage rate was 43.3%. Looking at the distribution serotypes, the rate of PCV10 serotypes rate was only 9.6%. Among non-vaccine serotypes, an increase in serotypes 6C/6D (22; 14%), 19B/19C (17; 10.8%), and 15B/15C (11; 7%) was observed. A particular increase in serotype diversity was also observed after the generalization of PCV10 (p < 0.001). S. pneumoniae non-susceptible to penicillin decreased, reaching a rate of 26.6% in 2017-2018. Conclusion The significant change in S. pneumoniae carriage, serotype distribution, and penicillin resistance highlights the effectiveness of the pneumococcal conjugate vaccine among children in Marrakesh, Morocco.
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Affiliation(s)
- Karima Warda
- Laboratory of Microbiology and Virology, Cadi Ayad University, Marrakesh, Morocco
| | - Sara Amari
- Laboratory of Microbiology and Virology, Cadi Ayad University, Marrakesh, Morocco
| | - Majda Boureddane
- Laboratory of Microbiology and Virology, Cadi Ayad University, Marrakesh, Morocco
| | - Youssef Elkamouni
- Laboratory of Microbiology and Virology, Cadi Ayad University, Marrakesh, Morocco
- Laboratory of Microbiology-Virology and Molecular Biology, Avicenna Military Hospital, Marrakesh, Morocco
| | - Lamiae Arsalane
- Laboratory of Microbiology and Virology, Cadi Ayad University, Marrakesh, Morocco
- Laboratory of Microbiology-Virology and Molecular Biology, Avicenna Military Hospital, Marrakesh, Morocco
| | - Said Zouhair
- Laboratory of Microbiology and Virology, Cadi Ayad University, Marrakesh, Morocco
- Laboratory of Microbiology-Virology and Molecular Biology, Avicenna Military Hospital, Marrakesh, Morocco
| | - Mohammed Bouskraoui
- Laboratory of Microbiology and Virology, Cadi Ayad University, Marrakesh, Morocco
- Department of Pediatrics, Mohamed VI University Hospital Center, Marrakesh, Morocco
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Müller A, Lekhuleni C, Hupp S, du Plessis M, Holivololona L, Babiychuk E, Leib SL, Grandgirard D, Iliev AI, von Gottberg A, Hathaway LJ. Meningitis-associated pneumococcal serotype 8, ST 53, strain is hypervirulent in a rat model and has non-haemolytic pneumolysin which can be attenuated by liposomes. Front Cell Infect Microbiol 2023; 12:1106063. [PMID: 36683678 PMCID: PMC9852819 DOI: 10.3389/fcimb.2022.1106063] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Accepted: 12/19/2022] [Indexed: 01/09/2023] Open
Abstract
Introduction Streptococcus pneumoniae bacteria cause life-threatening invasive pneumococcal disease (IPD), including meningitis. Pneumococci are classified into serotypes, determined by differences in capsular polysaccharide and both serotype and pneumolysin toxin are associated with disease severity. Strains of serotype 8, ST 53, are increasing in prevalence in IPD in several countries. Methods Here we tested the virulence of such an isolate in a rat model of meningitis in comparison with a serotype 15B and a serotype 14 isolate. All three were isolated from meningitis patients in South Africa in 2019, where serotype 8 is currently the most common serotype in IPD. Results and Discussion Only the serotype 8 isolate was hypervirulent causing brain injury and a high mortality rate. It induced a greater inflammatory cytokine response than either the serotype 15B or 14 strain in the rat model and from primary mixed-glia cells isolated from mouse brains. It had the thickest capsule of the three strains and produced non-haemolytic pneumolysin. Pneumolysin-sequestering liposomes reduced the neuroinflammatory cytokine response in vitro indicating that liposomes have the potential to be an effective adjuvant therapy even for hypervirulent pneumococcal strains with non-haemolytic pneumolysin.
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Affiliation(s)
- Annelies Müller
- Institute for Infectious Diseases, Faculty of Medicine, University of Bern, Bern, Switzerland
- Graduate School for Cellular and Biomedical Sciences, Faculty of Medicine, University of Bern, Bern, Switzerland
| | - Cebile Lekhuleni
- Centre for Respiratory Diseases and Meningitis, National Institute for Communicable Diseases, Division of the National Health Laboratory Service, Johannesburg, South Africa
- School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Sabrina Hupp
- Institute of Anatomy, University of Bern, Bern, Switzerland
| | - Mignon du Plessis
- Centre for Respiratory Diseases and Meningitis, National Institute for Communicable Diseases, Division of the National Health Laboratory Service, Johannesburg, South Africa
- School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Lalaina Holivololona
- Institute for Infectious Diseases, Faculty of Medicine, University of Bern, Bern, Switzerland
| | | | - Stephen L Leib
- Institute for Infectious Diseases, Faculty of Medicine, University of Bern, Bern, Switzerland
| | - Denis Grandgirard
- Institute for Infectious Diseases, Faculty of Medicine, University of Bern, Bern, Switzerland
| | | | - Anne von Gottberg
- Centre for Respiratory Diseases and Meningitis, National Institute for Communicable Diseases, Division of the National Health Laboratory Service, Johannesburg, South Africa
- School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Lucy J Hathaway
- Institute for Infectious Diseases, Faculty of Medicine, University of Bern, Bern, Switzerland
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Oyewole ORA, Latzin P, Brugger SD, Hilty M. Strain-level resolution and pneumococcal carriage dynamics by single-molecule real-time (SMRT) sequencing of the plyNCR marker: a longitudinal study in Swiss infants. MICROBIOME 2022; 10:152. [PMID: 36138483 PMCID: PMC9502908 DOI: 10.1186/s40168-022-01344-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Accepted: 08/05/2022] [Indexed: 06/16/2023]
Abstract
BACKGROUND Pneumococcal carriage has often been studied from a serotype perspective; however, little is known about the strain-specific carriage and inter-strain interactions. Here, we examined the strain-level carriage and co-colonization dynamics of Streptococcus pneumoniae in a Swiss birth cohort by PacBio single-molecule real-time (SMRT) sequencing of the plyNCR marker. METHODS A total of 872 nasal swab (NS) samples were included from 47 healthy infants during the first year of life. Pneumococcal carriage was determined based on the quantitative real-time polymerase chain reaction (qPCR) targeting the lytA gene. The plyNCR marker was amplified from 214 samples having lytA-based carriage for pneumococcal strain resolution. Amplicons were sequenced using SMRT technology, and sequences were analyzed with the DADA2 pipeline. In addition, pneumococcal serotypes were determined using conventional, multiplex PCR (cPCR). RESULTS PCR-based plyNCR amplification demonstrated a 94.2% sensitivity and 100% specificity for Streptococcus pneumoniae if compared to lytA qPCR. The overall carriage prevalence was 63.8%, and pneumococcal co-colonization (≥ 2 plyNCR amplicon sequence variants (ASVs)) was detected in 38/213 (17.8%) sequenced samples with the relative proportion of the least abundant strain(s) ranging from 1.1 to 48.8% (median, 17.2%; IQR, 5.8-33.4%). The median age to first acquisition was 147 days, and having ≥ 2 siblings increased the risk of acquisition. CONCLUSION The plyNCR amplicon sequencing is species-specific and enables pneumococcal strain resolution. We therefore recommend its application for longitudinal strain-level carriage studies of Streptococcus pneumoniae. Video Abstract.
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Affiliation(s)
- Oluwaseun Rume-Abiola Oyewole
- Institute for Infectious Diseases, University of Bern, Friedbühlstrasse 51, 3001, Bern, Switzerland
- Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland
| | - Philipp Latzin
- Division of Respiratory Medicine, Department of Pediatrics, Inselspital, University of Bern, Bern, Switzerland
| | - Silvio D Brugger
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Markus Hilty
- Institute for Infectious Diseases, University of Bern, Friedbühlstrasse 51, 3001, Bern, Switzerland.
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Zens KD, Baroutsou V, Fehr JS, Lang P. Pneumococcal Vaccination Coverage and Uptake Among Adults in Switzerland: A Nationwide Cross-Sectional Study of Vaccination Records. Front Public Health 2022; 9:759602. [PMID: 35174130 PMCID: PMC8841552 DOI: 10.3389/fpubh.2021.759602] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Accepted: 12/21/2021] [Indexed: 01/18/2023] Open
Abstract
Streptococcus pneumoniae, or pneumococcus, is a common, opportunistic pathogen which can cause severe disease, particularly in adults 65+. In Switzerland, vaccination is recommended for children under 5 and for adults with health predispositions; vaccination of healthy adults 65+ is not recommended. In 2020 we conducted a nationwide, cross-sectional survey of vaccination records to evaluate pneumococcal vaccination coverage and factors affecting uptake among adults 18–85. We found that nationwide coverage was 4.5% without significant regional differences. Coverage was comparable between men and women and between those aged 18–39 (3.0%) and 40–64 (3.2%). Coverage was significantly higher among those 65–85 (9.6%). While 2.7% of individuals reporting no health predisposition were vaccinated, 14.8% with asthma or chronic pulmonary disease, 27.1% with immunosuppression, 12.9% with diabetes, 11.6% with heart, liver, or kidney disease, and 25.9% with >1 health risk were vaccinated. Adjusted odds of vaccination for all health predispositions except heart, liver, or kidney disease were significantly increased. Among unvaccinated individuals “not enough information about the topic” and “not suggested by a doctor/healthcare provider” were the major reasons for abstaining from vaccination. Respondents reporting a health predisposition were significantly less likely to report “not at increased risk due to chronic health conditions or age” as a reason for not being vaccinated (3.7% vs. 29.1%) and were more likely to report willingness to be vaccinated in the future compared to those not-at-risk (54.2% vs. 39.9%). Our results indicate that pneumococcal vaccination coverage in Switzerland is low among both individuals 65–85 and among those with predisposing health risks. It appears that at-risk individuals are aware of their increased risk, but feel they do not have enough information on the topic to seek vaccination, or have not been recommended a vaccination by their physician.
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Affiliation(s)
- Kyra D. Zens
- Department of Public and Global Health, Epidemiology, Biostatistics and Prevention Institute, University of Zurich, Zurich, Switzerland
- Department of Viral Immunobiology, Institute for Experimental Immunology, University of Zurich, Zurich, Switzerland
| | - Vasiliki Baroutsou
- Department of Public and Global Health, Epidemiology, Biostatistics and Prevention Institute, University of Zurich, Zurich, Switzerland
- Department of Clinical Research, Faculty of Medicine, University of Basel, Basel, Switzerland
| | - Jan S. Fehr
- Department of Public and Global Health, Epidemiology, Biostatistics and Prevention Institute, University of Zurich, Zurich, Switzerland
- University Hospital, University of Zurich, Zurich, Switzerland
| | - Phung Lang
- Department of Public and Global Health, Epidemiology, Biostatistics and Prevention Institute, University of Zurich, Zurich, Switzerland
- *Correspondence: Phung Lang
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Casanova C, Küffer M, Leib SL, Hilty M. Re-emergence of invasive pneumococcal disease (IPD) and increase of serotype 23B after easing of COVID-19 measures, Switzerland, 2021. Emerg Microbes Infect 2021; 10:2202-2204. [PMID: 34723783 PMCID: PMC8648035 DOI: 10.1080/22221751.2021.2000892] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Incidence of invasive pneumococcal disease (IPD) has been low during the peak of the COVID-19 pandemic. In this study, we found that the IPD numbers again increased in Switzerland during the first six months of 2021 and that this coincides with the loosening of COVID-19 measures. Vaccine pneumococcal serotypes have continued to decrease and non-vaccine type serotype 23B has emerged (8% of the isolates in 2021). Worryingly, serotype 23B is associated with reduced susceptibility to penicillin.
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Affiliation(s)
- Carlo Casanova
- Swiss National Reference Center for Invasive Pneumococci (NZPn), Institute for Infectious Diseases, University of Bern, Bern, Switzerland.,Institute for Infectious Diseases, University of Bern, Bern, Switzerland
| | - Marianne Küffer
- Swiss National Reference Center for Invasive Pneumococci (NZPn), Institute for Infectious Diseases, University of Bern, Bern, Switzerland.,Institute for Infectious Diseases, University of Bern, Bern, Switzerland
| | - Stephen L Leib
- Swiss National Reference Center for Invasive Pneumococci (NZPn), Institute for Infectious Diseases, University of Bern, Bern, Switzerland.,Institute for Infectious Diseases, University of Bern, Bern, Switzerland
| | - Markus Hilty
- Swiss National Reference Center for Invasive Pneumococci (NZPn), Institute for Infectious Diseases, University of Bern, Bern, Switzerland.,Institute for Infectious Diseases, University of Bern, Bern, Switzerland
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Pediatric Invasive Pneumococcal Disease Three Years after PCV13 Introduction in the National Immunization Plan-The Continued Importance of Serotype 3. Microorganisms 2021; 9:microorganisms9071428. [PMID: 34361864 PMCID: PMC8304318 DOI: 10.3390/microorganisms9071428] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 06/28/2021] [Accepted: 06/29/2021] [Indexed: 11/21/2022] Open
Abstract
The introduction of pneumococcal conjugate vaccines PCV7 and PCV13 led to decreases in incidence of pediatric invasive pneumococcal disease (pIPD) and changes in serotype distribution. We evaluated the consequences of higher vaccine uptake after the introduction of PCV13 in the National Immunization Plan (NIP) in 2015. Besides culture and conventional serotyping, the use of molecular methods to detect and serotype pneumococci in both pleural and cerebrospinal fluid samples contributed to 30% of all pIPD (n = 232) in 2015–2018. The most frequently detected serotypes were: 3 (n = 59, 26%), 10A (n = 17, 8%), 8 (n = 16, 7%) and 19A (n = 10, 4%). PCV13 serotypes still accounted for 46% of pIPD cases. Serotypes not included in any currently available conjugate vaccine (NVT) are becoming important causes of pIPD, with the increases in serotypes 8 and 33F being of particular concern given the importance of serotype 8 in adult IPD and the antimicrobial resistance of serotype 33F isolates. This study highlights the importance of using molecular methods in pIPD surveillance since these allowed a better case ascertainment and the identification of serotype 3 as the leading cause of pIPD. Even in a situation of vaccine uptake >95% for 3 years, PCV13 serotypes remain important causes of pIPD.
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