Percorrer por autor "Martí, S."
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- Assessment of trimethoprim-sulfamethoxazole susceptibility testing methods for fastidious Haemophilus sppPublication . Sierra, Y.; Tubau, F.; González-Díaz, A.; Carrera-Salinas, A.; Moleres, J.; Bajanca-Lavado, P.; Garmendia, J.; Domínguez, M. Ángeles; Ardanuy, C.; Martí, S.To compare the determinants of trimethoprim-sulfamethoxazole resistance with established susceptibility values for fastidious Haemophilus spp., to provide recommendations for optimal trimethoprim-sulfamethoxazole measurement. We collected 50 strains each of Haemophilus influenzae and Haemophilus parainfluenzae at Bellvitge University Hospital. Trimethoprim-sulfamethoxazole susceptibility was tested by microdilution, E-test and disc diffusion using both Mueller-Hinton fastidious (MH-F) medium 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. Strains presented generally higher rates of trimethoprim-sulfamethoxazole 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 determinants were as follows: I95L and F154S/V in folA; 3- and 15-bp 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. Given the routine use of disc diffusion, a significant number of strains could potentially be miscategorized as susceptible to trimethoprim-sulfamethoxazole despite having resistance-related mutations. A simple modification to the current clinical resistance breakpoint given by the EUCAST guideline for MH-F ensures correct interpretation and correlation with the reference standard method of microdilution.
- First identification and molecular characterization of CTX-M-15 extended-spectrum β-lactamase and OXA-9 β-lactamase in Haemophilus influenzae in the Iberian PeninsulaPublication . González-Díaz, A.; Pinto, M.; Cadenas-Jiménez, I.; Duarte, S.; Ardanuy, C.; Ribeiro, M.M.; Martí, S.; Bajanca-Lavado, P.We describe, for the first time, the presence and characterization of CTX-M-15 and OXA-9 in two Haemophilus influenzae strains: PTHi-14525 (CTX-M-15) from Portugal and HUB-HI042681 (OXA-9) from Spain. Multidrug-resistant PTHi-14525 carried blaCTX-M-15 (two copies) and blaTEM-1 in an ICEHpaHUB5-like element. HUB-HI042681, resistant to β-lactams and aminoglycosides, carried a novel ICEHinHUB1. These findings highlight the genomic plasticity and expanded resistome of H. influenzae, raising concerns about treatment and emphasizing the need for continuous genomic surveillance.