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Publication
Characterization of Haemophilus influenzae from healthy children attending day-care centers in the Lisbon regiĆ³n, 2015-2019
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Advisor(s)
Abstract(s)
Haemophilus influenzae colonizes the human upper respiratory tract, where it can remain asymptomatically. It can also progress from colonizer to pathogen and cause mucosal or invasive infections. The aim of this study was to unravel epidemiological aspects of H. influenzae nasopharyngeal colonization in healthy children attending day-care centers in Portugal.
Methods
Between 2015 and 2019, 1518 nasopharyngeal samples were collected from children up to six years old, attending day-care centers in Lisbon region. Samples were cultured in chocolate agar with bacitracin and isovitalex and screened for the presence of H. influenzae based on colony morphology. Pure cultures were obtained and capsular serotype was determined by PCR. Ī²-lactamase production was assessed with nitrocefin. Antibiotic susceptibility was determined for all Ī²-lactamase producer isolates and all encapsulated isolates by a microdilution assay. Genetic characterization based on whole genome sequencing (WGS) analysis was performed for encapsulated isolates.
Results
H. influenzae was presumptively identified in 1280 samples indicating a high carriage rate (84.3%). Of these, most isolates (96.7%) were non-encapsulated (NT). The 42 encapsulated isolates belonged to serotypes a (n=4), b (n=1), e (n=14), and f (n=23). A total of 7.5% (n=96) of the isolates were Ī²-lactamase producers although a higher percentage (11.9%) was observed in encapsulated isolates. Most isolates were susceptible to all antimicrobials tested. MLST revealed low genetic variability among encapsulated isolates: Hia-ST23, Hib-ST6, Hie-ST18 and ST122; and Hif-ST124, ST973 and ST2346. Analysis of presence/absence of 105 virulence genes showed that this is associated with the serotype, with serotype b isolates having the highest number of virulence genes. Virulence genes associated with specific structures or functions, such as iron acquisition, adherence, biofilm development or immune evasion, were present in all isolates.
Conclusion
Our results show that, in children attending day-care centers in the Lisbon region, the proportion of H. influenzae carriers is high and that circulation of encapsulated isolates is rare. Characterization of circulating isolates is important for community surveillance as these isolates may progress to cause severe invasive disease.
Description
Keywords
Haemophilus influenzae H. influenzae Colonization Children Serotypes Antibiotic Resistence Whole Genome Sequencing InfecƧƵes RespiratĆ³rias ResistĆŖncia aos Antimicrobianos
Pedagogical Context
Citation
MP Bajanca-Lavado, L.F: Cavaco, M. Fernandes T. Touret, Candeias C, R. SĆ”-LeĆ£o. Characterization of Haemophilus influenzae from healthy children attending day-care centers in the Lisbon regiĆ³n, 2015-2019. Poster (03711) apresentado no 31st ECCMID