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Assessment of trimethoprim-sulfamethoxazole susceptibility testing methods for fastidious Haemophilus spp.

2020-04-21Conference object Open access
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dc.contributor.authorSierra, Y.
dc.contributor.authorGonzález-Díaz, A.
dc.contributor.authorTubau, F.
dc.contributor.authorCarrera-Salinas, A.
dc.contributor.authorMoleres, J.
dc.contributor.authorBajanca-Lavado, Maria Paula
dc.contributor.authorGarmendia, J.
dc.contributor.authorDomínguez, M.
dc.contributor.authorArdanuy, C.
dc.contributor.authorMarti, S.
dc.date.accessioned2020-10-26T18:17:32Z
dc.date.available2020-10-26T18:17:32Z
dc.date.issued2020-04-21
dc.description.abstractBackground: Several discrepancies were found in clinical routine regarding trimethoprim-sulfamethoxazole (SXT) susceptibility determination depending on antimicrobial susceptibility (AST) method used and growth media. We aimed to compare the determinants of SXT resistance with established susceptibility values for fastidious Haemophilus spp., in order to provide recommendations for optimal SXT measurement. Materials/methods: We collected 50 strains each of Haemophilus influenzae and Haemophilus parainfluenzae at Bellvitge University Hospital. SXT susceptibility was tested by microdilution, E-test, and disc diffusion using both Mueller-Hinton Fastidious (MH-F) and Haemophilus Test Medium (HTM) following EUCAST and CLSI criteria respectively. Mutations in folA, folP and additional determinants of resistance were identified in whole-genome sequenced isolates. Results: Strains presented generally higher rates of SXT resistance when grown on HTM than on MH-F, independent of the methodology used (average MIC 2.6-fold higher in H. influenzae and 1.2-fold higher in H. parainfluenzae). The main resistance-related mechanisms were as follows: I95L and F154S/V in FolA; 3 and 15 base pair insertions and substitutions in folP; acquisition of sul genes; and FolA overproduction potentially linked to mutations in -35 and -10 promoter motifs. Of note, 2 of 19 H. influenzae strains (10.5%) and 9 of 33 H. parainfluenzae strains (27.3%) with mutations and assigned as resistant by microdilution were inaccurately considered susceptible by disc diffusion. This misinterpretation was resolved by raising the clinical resistance breakpoint of the EUCAST guidelines to ≤30 mm. Conclusions: Given the routine use of disc diffusion, a significant number of strains could potentially be miscategorised as susceptible to SXT despite having resistance-related mechanisms. A simple modification to the current clinical resistance breakpoint given by the EUCAST guideline for MH-F ensures correct interpretation and correlation with the gold-standard method of microdilution.pt_PT
dc.description.versionN/Apt_PT
dc.identifier.citation30th European Congress of Clinical Microbiology and Infectious Diseases (ECCMID). Poster 150 Y. Sierra, A. González-Díaz, F. Tubau, A. Carrera-Salinas, J. Moleres, P. Bajanca-Lavado, J. Garmendia, M. Domínguez, C. Ardanuy, S. Marti Assessment of trimethoprim-sulfamethoxazole susceptibility testing methods for fastidious Haemophilus spp.pt_PT
dc.identifier.urihttp://hdl.handle.net/10400.18/7214
dc.language.isoengpt_PT
dc.peerreviewedyespt_PT
dc.rights.urihttp://creativecommons.org/licenses/by/4.0/pt_PT
dc.subjectHaemophilus spp.pt_PT
dc.subjectTrimethoprim-sulfamethoxazolept_PT
dc.subjectSusceptibilitypt_PT
dc.subjectResistência aos Antimicrobianospt_PT
dc.titleAssessment of trimethoprim-sulfamethoxazole susceptibility testing methods for fastidious Haemophilus spp.pt_PT
dc.typeconference object
dspace.entity.typePublication
oaire.citation.conferencePlaceParis, Françapt_PT
oaire.citation.title30th European Congress of Clinical Microbiology and Infectious Diseases (ECCMID),18-21 April 2020pt_PT
person.familyNameBajanca Lavado
person.givenNameMaria Paula
person.identifier.ciencia-id2B11-E245-3D39
person.identifier.orcid0000-0002-1453-0315
person.identifier.scopus-author-id6506614938
rcaap.rightsopenAccesspt_PT
rcaap.typeconferenceObjectpt_PT
relation.isAuthorOfPublication31093b71-e0a5-4796-8b01-12f4eccfc57a
relation.isAuthorOfPublication.latestForDiscovery31093b71-e0a5-4796-8b01-12f4eccfc57a

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