Predictors for Haemophilus influenzae colonization, antibiotic resistance and for sharing an identical isolate among children attending 16 licensed day-care centers in Michigan.
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 > or = 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 beta-lactamase-producing strain. Colonized children were more likely to carry resistant strains if they were taking an antibiotic (P = 0.02).


CONCLUSIONS
Although day-care center colonization varied, the overall colonization rate was high. Colonization with nontypable H. influenzae, with beta-lactamase-producing strain and sharing were, mostly, associated with modifiable risk factors.
Barbosa-Cesnik
Cibele
C
Department of Epidemiology, University of Michigan, School of Public Health, Ann Arbor, MI 48109, USA. cibele@umich.edu
Farjo
Rand S
RS
Patel
May
M
Gilsdorf
Janet
J
McCoy
Sandra I
SI
Pettigrew
Melinda M
MM
Marrs
Carl
C
Foxman
Betsy
B
D002353:Carrier State / Q000453:epidemiology* / Q000382:microbiology; D002656:Child Day Care Centers; D002675:Child, Preschool; D024881:Drug Resistance, Bacterial; D006192:Haemophilus Infections / Q000453:epidemiology* / Q000382:microbiology; D006193:Haemophilus influenzae / Q000145:classification / Q000187:drug effects / Q000201:enzymology / Q000302:isolation & purification; D006801:Humans; D007223:Infant; D016015:Logistic Models; D008824:Michigan / Q000453:epidemiology; D015999:Multivariate Analysis; D010614:Pharynx / Q000382:microbiology; D011237:Predictive Value of Tests; D012307:Risk Factors; D011795:Surveys and Questionnaires; D001618:beta-Lactamases / Q000378:metabolism
D001618:beta-Lactamases