Caracterização de amostras de Haemophilus influenzae, Moraxella catarrhalis e Streptococcus pneumoniae isoladas de colonização de nasofaringe em crianças atendidas em um hospital universitário do Rio de Janeiro

Abstract

Colonization of the nasopharynx is an important stage in the development of respiratory tract infections. The bacterial species Haemophilus influenzae (Hi), Moraxella catarrhalis (Mc) and Streptococcus pneumoniae (Sp) stand out in the pediatric population. The objective of this study was to isolate and characterize bacterial samples belonging to these species, from nasopharyngeal colonization of children treated at HUPE / UERJ. During the year 2015, eight collections of clinical material were carried out for a total of 204 children. The specimens (nasopharynx swabs) were seeded in 5% sheep blood agar and chocolate agar supplemented with hemin and NAD, and the plates incubated for up to 48 h at 37 ° C in 5% CO2 atmosphere. Bacterial samples were characterized in genus and species by MALDI-TOF and conventional physiological tests. The capsular Hi types were defined by Latex and Sp agglutination methods by PCR using a set of PCV10 vaccine primers. Antimicrobial susceptibility profiles were determined in the Hi and Sp samples. Resistance phenotypes to erythromycin and clindamycin Were identified by the double-disc test, oxacillin-resistant samples and erythromycin, in Sp, the MIC was determined by the E test. Beta-lactam resistant samples of Hi and Mc samples were evaluated for beta-lactamase expression. Spectra obtained by MALDI-TOF MS evaluated the diversity, using algorithms for the grouping of samples and construction of similarity trees. The results showed colonization rate 40.2% (82/204), being 15.7% Hi, 25.5% Mc and 21.1% Sp. The isolation of the species, in the seasons of the year, revealed more expressive values of Mc in the spring; While the others in the summer. Most of the Hi samples were non-typing (HiNT, 83.3%), only one sample identified as Hib and four others as non-Hib. Likewise, for Sp, only five samples were PCR-typed, four of which were 6A / B and one 23F, 87.5% did not show amplification products. Among the antimicrobial resistance phenotypes, oxacillin and erythromycin in Sp and ampicillin in Hi are the most important. MIC values for penicillin and erythromycin corroborate the findings in Sp. All ampicillin-resistant Hi samples were HiNT beta-lactamase producing, 96.0% Mc samples were also producers of this enzyme. The cluster analysis of the spectra by MALDI-TOF MS revealed diversity of the samples, prevalent clusters and defined subgroups. We emphasize the frequency of 87.7% in vaccinated children, with emphasis on the new phenotypes in percentages. The association of new antimicrobial resistance phenotypes reflects the need to monitor these species in the search for control strategies. This study aimed to contribute with national data to understand the circulation of these respiratory pathogens in this population.