Background: Nasal bacterial colonization is often dubbed “asymptomatic.” We hypothesized that rhinitis, common in preschool children, is associated with bacterial colonization and that respiratory viruses, which cause rhinitis, interact with bacteria in ways which promote transmission.
Methods: Five hundred eighty-five children (4.2–73.6 months) attending daycare had clinical information, a rhinitis score and nasal swabs collected in February 2009. Swabs in soya tryptone glucose glycerine broth were cultured for Streptococcus pneumoniae (Sp), Haemophilus influenzae (Hi) and Staphylococcus aureus and analyzed by real-time polymerase chain reaction for respiratory viruses, both semiquantitatively.
Results: Rhinitis symptoms, carriage of Sp and Hi and viral infection fell, whereas S. aureus carriage rates rose with age. Significant, age-independent associations between rhinitis symptoms and detection of Hi (P < 0.033) and Hi colonization density (P < 0.027) were observed. Of the 42% with detected viruses, most (78%) had picornavirus infection. There was a significant age-independent association between viral infection (and viral load, picornavirus infection and picornaviral load) and detection of Sp (P = 0.020, 0.035, 0.005, 0.014) and between viral infection and viral load and Sp colonization density (P = 0.024, 0.028).
Conclusions: Hi may promote its own transmission by inducing or amplifying rhinitis in children. There is a close quantitative relationship between respiratory viral infection, including picornavirus infection and Sp colonization. These findings have implications for understanding disease pathogenesis and formulating prevention strategies using vaccines.
From the *Infectious Diseases Unit and Emergency Service, Centro de Investigação e Formação Clinica, Hospital Pediátrico de Coimbra, Centro Hospitalar e Universitário de Coimbra, Faculdade de Medicina, Universidade de Coimbra, Coimbra, Portugal; †Nuffield Department of Medicine, University of Oxford, Oxford; ‡School of Social and Community Medicine, University of Bristol; §Health Protection Agency Virology Laboratory, Bristol, United Kingdom; ¶Instituto de Ciências Médicas Abel Salazar, Universidade do Porto, Porto; Infectious Diseases Unit and Emergency Service, Hospital Pediátrico de Coimbra, Centro Hospitalar e Universitário de Coimbra, Coimbra, Portugal; and **Bristol Children’s Vaccine Centre, School of Clinical Sciences and Cellular and Molecular Medicine, University of Bristol, Bristol, United Kingdom.
Accepted for publication September 27, 2012.
E.N. received a grant from the UK Medical Research Council. The authors have no other funding or conflicts of interest to disclose.
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Address for correspondence: Fernanda Rodrigues, MD, Infectious Diseases Unit and Emergency Service, Hospital Pediátrico de Coimbra, Centro Hospitalar e Universitário de Coimbra, Av. Afonso Romão, Alto da Baleia, 3000–602 Coimbra, Portugal. E-mail: firstname.lastname@example.org.