Background: Nontypable Haemophilus influenzae is an important cause of otitis media in children. Children attending day-care centers are at an increased risk for nontypable H. influenzae colonization and otitis media. We describe the prevalence of nontypable H. influenzae colonization, antibiotic resistance and predictors for colonization and sharing an identical isolate with at least 1 other child in the same day-care centers among children attending 16 day-care centers.
Methods: Throat swabs of 198 children <3 years old attending 16 day-care centers were cultured for H. influenzae. Day-care center directors and parents completed risk factors questionnaires. Nontypable H. influenzae isolates were screened for antibiotic resistance and genotyped. Statistics were performed using SAS software (SAS Institute, Inc., Cary, NC).
Results: We isolated 179 unique nontypable H. influenzae strains from 127 participants. Colonization ranged from 0% to 95% among day-care centers. As individual factors, exposure to tobacco smoke was associated with colonization (P = 0.05), and racial self-identifications as “other”(nonwhite, nonblack) was protective (P = 0.035), whereas as “black” was protective for sharing (P = 0.03). Pacifier use was associated with sharing (P = 0.04), but not with colonization. As day-care centers factors, rates of colonization and sharing were higher in day-care centers with ≥5 classrooms (P < 0.01 and P = 0.03), with such suboptimal hygiene habits as minimal hand washing by staff after eating (P < 0.002 and P < 0.01) or by children after wiping their own nose (P = 0.01 and P = 0.003). Of colonized children, 41% presented a β-lactamase-producing strain. Colonized children were more likely to carry resistant strains if they were taking an antibiotic (P = 0.02).
Conclusion: Although day-care center colonization varied, the overall colonization rate was high. Colonization with nontypable H. influenzae, with β-lactamase-producing strain and sharing were, mostly, associated with modifiable risk factors.
From the *Department of Epidemiology, University of Michigan, School of Public Health; and the †Department of Pediatrics and Communicable Diseases, University of Michigan, Ann Arbor, MI
Accepted for publication October 19, 2005.
Dr Gilsdorf was supported by Public Health Services grant AI25630 from the National Institute of Allergy and Infectious Diseases. Drs Gilsdorf and Pettigrew were supported by a grant from the Deafness Research Foundation. Collection of throat cultures was funded by a grant from the Michigan Department of Community Health and Michigan Antibiotic Resistance Reduction Coalition (to Dr Foxman).
Dr Farjo's current address is the Department of Pediatrics, St. John Hospital and Health System, Detroit, MI. Dr McCoy's current address is the Department of Epidemiology, the University of North Carolina at Chapel Hill, Chapel Hill, NC. Dr Pettigrew's current address is Yale University, School of Public Health.
Tables 1–4 are available on line at the journal website, www.pidj.com.
Address for reprints: Cibele Barbosa-Cesnik, MD, MPH, Department of Epidemiology, University of Michigan, School of Public Health, 109 S. Observatory, Ann Arbor, MI 48109. Fax 734-936-6732; E-mail firstname.lastname@example.org.