Browsing by Author "Candeias, Catarina"
Now showing 1 - 2 of 2
Results Per Page
Sort Options
- Characterization of Haemophilus influenzae from healthy children attending day-care centers in the Lisbon región, 2015-2019Publication . Bajanca Lavado, Maria Paula; Cavaco, Luís Filipe; Fernandes, Mariana; Touret, Tiago; Candeias, CatarinaHaemophilus 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. β-lactamase production was assessed with nitrocefin. Antibiotic susceptibility was determined for all β-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 β-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.
- Haemophilus influenzae Carriage among Healthy Children in Portugal, 2015-2019Publication . Bajanca-Lavado, Maria Paula; Cavaco, Luís; Fernandes, Mariana; Touret, Tiago; Candeias, Catarina; Simões, Alexandra S.; Sá-Leão, RaquelHaemophilus influenzae is an important cause of mucosal and invasive infections and a common colonizer of the upper respiratory tract. As there are no recent data on H. influenzae carriage in Portugal, we aimed to characterize carriage samples and investigate possible parallelisms with disease isolates. Between 2016–2019, 1524 nasopharyngeal samples were obtained from children (0–6 years) attending day-care. H. influenzae were serotyped and screened for β-lactamase production. Strains producing β-lactamase and/or those that were encapsulated were further characterized by antibiotype; encapsulated strains were also investigated for MLST and the presence of antimicrobial resistance and virulence genes (extracted from whole genome sequencing). The overall carriage rate was 84.1%. Most isolates (96.7%) were nonencapsulated. Encapsulated strains were of serotypes f (1.8%), e (1.1%), a (0.3%), and b (0.1%). MLST showed clonality within serotypes. Although the lineages were the same as those that were described among disease isolates, colonization isolates had fewer virulence determinants. Overall, 7.5% of the isolates were β-lactamase positive; one isolate had blaTEM-82, which has not been previously described in H. influenzae. A single isolate, which was identified as H. parainfluenzae, had an incomplete f-like cap locus. In conclusion, circulation of serotype b is residual. The few encapsulated strains are genetically related to disease-causing isolates. Thus, surveillance of H. influenzae carriage should be maintained.