title: Multi-serotype pneumococcal nasopharyngeal carriage prevalence in vaccine naïve Nepalese children, assessed using molecular serotyping.
abstract: Invasive pneumococcal disease is one of the major causes of death in young children in resource poor countries. Nasopharyngeal carriage studies provide insight into the local prevalence of circulating pneumococcal serotypes. There are very few data on the concurrent carriage of multiple pneumococcal serotypes. This study aimed to identify the prevalence and serotype distribution of pneumococci carried in the nasopharynx of young healthy Nepalese children prior to the introduction of a pneumococcal conjugate vaccine using a microarray-based molecular serotyping method capable of detecting multi-serotype carriage. We conducted a cross-sectional study of healthy children aged 6 weeks to 24 months from the Kathmandu Valley, Nepal between May and October 2012. Nasopharyngeal swabs were frozen and subsequently plated on selective culture media. DNA extracts of plate sweeps of pneumococcal colonies from these cultures were analysed using a molecular serotyping microarray capable of detecting relative abundance of multiple pneumococcal serotypes. 600 children were enrolled into the study: 199 aged 6 weeks to <6 months, 202 aged 6 months to < 12 months, and 199 aged 12 month to 24 months. Typeable pneumococci were identified in 297/600 (49.5%) of samples with more than one serotype being found in 67/297 (20.2%) of these samples. The serotypes covered by the thirteen-valent pneumococcal conjugate vaccine were identified in 44.4% of samples containing typeable pneumococci. Application of a molecular serotyping approach to identification of multiple pneumococcal carriage demonstrates a substantial prevalence of co-colonisation. Continued surveillance utilising this approach following the introduction of routine use of pneumococcal conjugate vaccinates in infants will provide a more accurate understanding of vaccine efficacy against carriage and a better understanding of the dynamics of subsequent serotype and genotype replacement.
authors: Oxford Vaccine Group, Department of Paediatrics, University of Oxford, Oxford, United Kingdom; NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom.
authors: Rama
authors: R
authors: Kandasamy
authors: Paediatric Research Unit, Patan Academy of Health Sciences, Kathmandu, Nepal.
authors: Meeru
authors: M
authors: Gurung
authors: Paediatric Research Unit, Patan Academy of Health Sciences, Kathmandu, Nepal.
authors: Anushil
authors: A
authors: Thapa
authors: Oxford Vaccine Group, Department of Paediatrics, University of Oxford, Oxford, United Kingdom; NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom.
authors: Susan
authors: S
authors: Ndimah
authors: Paediatric Research Unit, Patan Academy of Health Sciences, Kathmandu, Nepal.
authors: Neelam
authors: N
authors: Adhikari
authors: Department of Pathology, University of Otago, Christchurch, New Zealand.
authors: David R
authors: DR
authors: Murdoch
authors: Oxford Vaccine Group, Department of Paediatrics, University of Oxford, Oxford, United Kingdom; NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom.
authors: Dominic F
authors: DF
authors: Kelly
authors: Division of Clinical Sciences, St. George's, University of London, London, United Kingdom.
authors: Denise E
authors: DE
authors: Waldron
authors: Division of Clinical Sciences, St. George's, University of London, London, United Kingdom.
authors: Katherine A
authors: KA
authors: Gould
authors: Paediatric Research Unit, Patan Academy of Health Sciences, Kathmandu, Nepal.
authors: Stephen
authors: S
authors: Thorson
authors: Paediatric Research Unit, Patan Academy of Health Sciences, Kathmandu, Nepal.
authors: Shrijana
authors: S
authors: Shrestha
authors: Division of Clinical Sciences, St. George's, University of London, London, United Kingdom.
authors: Jason
authors: J
authors: Hinds
authors: Oxford Vaccine Group, Department of Paediatrics, University of Oxford, Oxford, United Kingdom; NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom.
authors: Andrew J
authors: AJ
authors: Pollard
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002353:Carrier State; D002675:Child, Preschool; D024881:Drug Resistance, Bacterial / Q000235:genetics; D006801:Humans; D007223:Infant; D008297:Male; D009305:Nasopharynx / Q000382:microbiology*; D009390:Nepal; D022242:Pneumococcal Vaccines; D015995:Prevalence; D012703:Serotyping; D013296:Streptococcus pneumoniae / Q000145:classification* / Q000187:drug effects / Q000235:genetics / Q000276:immunology
chemical_list: D000900:Anti-Bacterial Agents; D022242:Pneumococcal Vaccines
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