Pharyngeal carriage and antimicrobial resistance of Haemophilus influenzae in non-type-b-vaccinated healthy children attending day care centers in Turkey

Abstract

Background: The true prevalence of Haemophilus influenzae carriage rates in Turkey is unknown. As surveillance of pharyngeal carriage of resistant strains is important for initiating adequate empirical antimicrobial therapy, with the present study, we aimed to determine the carriage rates and antimicrobial resistance patterns of H. influenzae isolated from healthy children attending day care centers (DCCs) in Istanbul, Turkey.

Methods: A total of 195 healthy children were included from two DCCs. Pharyngeal swabs were cultured for H. influenzae which were identified according to standard microbiologic procedures. Antimicrobial susceptibility tests were performed by the agar dilution method in accordance with the guidelines of the National Committee for Clinical Laboratory standards. beta-Lactamase production was determined by the nitrocefin disc test.

Results: The average pharyngeal carriage rate of H. influenzae was determined as 48.7%: 7.2% type b, 7.6% other capsulated strains, 33.9% noncapsulated strains, with a carriage peak between 0 and 11 months (68.1%). The ampicillin resistance observed in 7.3% of H. influenzae isolates was associated with a presence of beta-lactamase, except for one isolate which was interpreted as beta-lactamase-negative ampicillin-resistant strain. The resistance of H. influenzae to sulbactam/ampicillin, cefuroxime, azithromycin, tetracycline and cotrimoxazole was 0.5, 1.5, 0.5, 2.9 and 28.6%, respectively. Cefotaxime, ceftriaxone, ciprofloxacin and imipenem resistance was not detected.

Conclusion: Our data show that the upper respiratory tract of about 48.7% of children was colonized with H. influenzae. This high colonization rate indicates that there is a need for surveillance of pharyngeal carriage of resistant strains in healthy Turkish children attending DCCs.