Associations between pathogens in the upper respiratory tract of young children: interplay between viruses and bacteria.
BACKGROUND
High rates of potentially pathogenic bacteria and respiratory viruses can be detected in the upper respiratory tract of healthy children. Investigating presence of and associations between these pathogens in healthy individuals is still a rather unexplored field of research, but may have implications for interpreting findings during disease.


RESULTS
We selected 986 nasopharyngeal samples from 433 6- to 24-month-old healthy children that had participated in a randomized controlled trial. We determined the presence of 20 common respiratory viruses using real-time PCR. Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis and Staphylococcus aureus were identified by conventional culture methods. Information on risk factors was obtained by questionnaires. We performed multivariate logistic regression analyses followed by partial correlation analysis to identify the overall pattern of associations. S. pneumoniae colonization was positively associated with the presence of H. influenzae (adjusted odds ratio 1.60, 95% confidence interval 1.18-2.16), M. catarrhalis (1.78, 1.29-2.47), human rhinoviruses (1.63, 1.19-2.22) and enteroviruses (1.97, 1.26-3.10), and negatively associated with S. aureus presence (0.59, 0.35-0.98). H. influenzae was positively associated with human rhinoviruses (1.63, 1.22-2.18) and respiratory syncytial viruses (2.78, 1.06-7.28). M. catarrhalis colonization was positively associated with coronaviruses (1.99, 1.01-3.93) and adenoviruses (3.69, 1.29-10.56), and negatively with S. aureus carriage (0.42, 0.25-0.69). We observed a strong positive association between S. aureus and influenza viruses (4.87, 1.59-14.89). In addition, human rhinoviruses and enteroviruses were positively correlated (2.40, 1.66-3.47), as were enteroviruses and human bocavirus, WU polyomavirus, parainfluenza viruses, and human parechovirus. A negative association was observed between human rhinoviruses and coronaviruses.


CONCLUSIONS
Our data revealed high viral and bacterial prevalence rates and distinct bacterial-bacterial, viral-bacterial and viral-viral associations in healthy children, hinting towards the complexity and potential dynamics of microbial communities in the upper respiratory tract. This warrants careful consideration when associating microbial presence with specific respiratory diseases.
Department of Pediatric Immunology and Infectious Diseases, Wilhelmina Children's Hospital, University Medical Center Utrecht, Utrecht, The Netherlands.
Menno R
MR
van den Bergh
Giske
G
Biesbroek
John W A
JW
Rossen
Wouter A A
WA
de Steenhuijsen Piters
Astrid A T M
AA
Bosch
Elske J M
EJ
van Gils
Xinhui
X
Wang
Chantal W B
CW
Boonacker
Reinier H
RH
Veenhoven
Jacob P
JP
Bruin
Debby
D
Bogaert
Elisabeth A M
EA
Sanders
D001419:Bacteria / Q000254:growth & development / Q000378:metabolism*; D002675:Child, Preschool; D015169:Colony Count, Microbial; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D056265:Microbial Interactions; D009305:Nasopharynx / Q000382:microbiology / Q000821:virology; D016017:Odds Ratio; D012137:Respiratory System / Q000382:microbiology* / Q000473:pathology / Q000821:virology*; D012141:Respiratory Tract Infections / Q000382:microbiology* / Q000821:virology*; D012307:Risk Factors; D014780:Viruses / Q000378:metabolism*