Volume 20, Number 2—February 2014
Nasopharyngeal Bacterial Interactions in Children
Highlight and copy the desired format.
|EID||Suzuki M, Dhoubhadel B, Yoshida L, Ariyoshi K. Nasopharyngeal Bacterial Interactions in Children. Emerg Infect Dis. 2014;20(2):323-324. https://dx.doi.org/10.3201/eid2002.121724|
|AMA||Suzuki M, Dhoubhadel B, Yoshida L, et al. Nasopharyngeal Bacterial Interactions in Children. Emerging Infectious Diseases. 2014;20(2):323-324. doi:10.3201/eid2002.121724.|
|APA||Suzuki, M., Dhoubhadel, B., Yoshida, L., & Ariyoshi, K. (2014). Nasopharyngeal Bacterial Interactions in Children. Emerging Infectious Diseases, 20(2), 323-324. https://dx.doi.org/10.3201/eid2002.121724.|
To the Editor: Xu and colleagues (1) examined the nasopharyngeal bacterial colonization rates in children with acute otitis media (AOM) and in healthy children. They found that Haemophilus influenzae colonization was competitively associated with Streptococcus pneumoniae and Morexella catarrhalis colonization in children with AOM but was not associated with S. pneumoniae and M. catarrhalis colonization in healthy children. We have a serious concern regarding their analysis.
The authors calculated odds ratios (ORs) by considering a bacterial colonization as an outcome variable and another bacterial colonization as an exposure variable. They considered an OR >1 as the presence of synergistic associations between bacteria (i.e., co-colonization is more likely to occur than it would by chance) and OR <1 as the presence of competitive associations (i.e., co-colonization is less likely to occur than it would by chance). This inference may be justified in a population-based cross-sectional study. If 2 bacterial colonizations occur independently in a stationary population, the prevalence of co-colonization will be the product (multiplication) of each prevalence, and the OR between 2 bacterial colonizations in the population (ORpop) will be 1 (Technical Appendix [PDF - 61 KB - 3 pages]).
However, the authors enrolled their case-patients according to clinical signs (i.e., AOM or healthy). Let us assume that case-patients are enrolled from a population of children during a time period of t. Let rc be the risk for enrollment (that is, of developing the disease) among colonized children and rn be the risk for enrollment among noncolonized children. The OR among the enrolled case-patients (ORcase-patient) becomes rn/rc, which is the reciprocal of the risk ratio (RR) of developing the disease (RR = rc/rn) (online Technical Appendix). Usually, RR is >1 for diseased children and <1 for healthy children. Therefore, even in this independent colonization scenario, ORcase-patient becomes <1 (“pseudo-competitive associations”) in diseased children, and ORcase-patient becomes >1 (“pseudo-synergistic associations”) in healthy children. This is probably what the authors have observed in the study.
We cannot infer an association of multiple bacterial colonizations in a population despite an observed association in the diseased (or healthy) children, and this association is widely misunderstood (2–4). The authors’ discussion regarding a potential emergence of H. influenzae, associated with AOM, after the introduction of pneumococcal conjugate vaccine is thus unjustifiable.
- Xu Q, Almudervar A, Casey JR, Pichichero ME. Nasopharyngeal bacterial interactions in children. Emerg Infect Dis. 2012;18:1738–45.
- Regev-Yochay G, Dagan R, Raz M, Carmeli Y, Shainberg B, Derazne E, Association between carriage of Streptococcus pneumoniae and Staphylococcus aureus in children. JAMA. 2004;292:716–20.
- Pettigrew MM, Gent JF, Revai K, Patel JA, Chonmaitree T. Microbial interactions during upper respiratory tract infections. Emerg Infect Dis. 2008;14:1584–91.
- Brunstein JD, Cline CL, McKinney S, Thomas E. Evidence from multiplex molecular assays for complex multipathogen interactions in acute respiratory infections. J Clin Microbiol. 2008;46:97–102.
- Technical Appendix. . Number of children by bacterial colonization status in a stationary population and case-patients enrolled during a specified period. 61 KB
Please use the form below to submit correspondence to the authors or contact them at the following address:
Motoi Suzuki, Department of Clinical Medicine, Institute of Tropical Medicine, Nagasaki University, Sakamoto 1-12-4, Nagasaki 852-8523, JapanMotoi Suzuki, Department of Clinical Medicine, Institute of Tropical Medicine, Nagasaki University, Sakamoto 1-12-4, Nagasaki 852-8523, Japan
Comment submitted successfully, thank you for your feedback.
The conclusions, findings, and opinions expressed by authors contributing to this journal do not necessarily reflect the official position of the U.S. Department of Health and Human Services, the Public Health Service, the Centers for Disease Control and Prevention, or the authors' affiliated institutions. Use of trade names is for identification only and does not imply endorsement by any of the groups named above.
- Page created: January 16, 2014
- Page last updated: January 16, 2014
- Page last reviewed: January 16, 2014
- Centers for Disease Control and Prevention,
National Center for Emerging and Zoonotic Infectious Diseases (NCEZID)
Office of the Director (OD)