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1.
Int J Antimicrob Agents ; 62(5): 106991, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-37774891

RESUMO

Haemophilus parainfluenzae is a commensal organism with rising numbers of multidrug-resistant (MDR) strains. This pathogen is of increasing clinical relevance in urogenital infection. The aim of this work was to identify and characterise the molecular mechanisms of resistance associated with four cephalosporin-resistant H. parainfluenzae strains collected from patients with urethritis. Antimicrobial resistance was determined by microdilution following European Committee on Antimicrobial Susceptibility Testing criteria. Strains were then analysed by whole-genome sequencing to determine clonal relationship and the molecular basis of antimicrobial resistance. Finally, a phylogenetic analysis was performed on all urogenital MDR strains of H. parainfluenzae previously isolated in our hospital. All strains were resistant to ß-lactams, macrolides, tetracycline, fluoroquinolones, chloramphenicol, cotrimoxazole, and aminoglycosides. The resistance profile was compatible with the presence of an extended-spectrum ß-lactamase (ESBL). Whole-genome sequencing detected blaCTX-M-15 that conferred high minimum inhibitory concentrations to cephalosporins in two novel integrative and conjugative elements (ICEHpaHUB6 and ICEHpaHUB7) that also harboured a blaTEM-1 ß-lactamase. This study shows a novel blaCTX-M-15 ESBL carried in an integrative conjugative element in four extensively drug-resistant H. parainfluenzae strains. This resistance determinant could be transmitted to other sexually transmitted pathogens and this is a cause for concern.


Assuntos
Haemophilus parainfluenzae , Uretrite , Humanos , Haemophilus parainfluenzae/genética , Uretrite/tratamento farmacológico , Filogenia , Antibacterianos/farmacologia , Antibacterianos/uso terapêutico , Cefalosporinas/farmacologia , beta-Lactamases/genética , Testes de Sensibilidade Microbiana
2.
Clin Microbiol Infect ; 26(7): 944.e1-944.e7, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31811916

RESUMO

OBJECTIVES: To compare the determinants of trimethoprim-sulfamethoxazole resistance with established susceptibility values for fastidious Haemophilus spp., to provide recommendations for optimal trimethoprim-sulfamethoxazole measurement. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.


Assuntos
Proteínas de Bactérias/genética , Farmacorresistência Bacteriana Múltipla , Infecções por Haemophilus/microbiologia , Haemophilus influenzae/genética , Haemophilus parainfluenzae/genética , Antibacterianos/farmacologia , Meios de Cultura/química , Haemophilus influenzae/efeitos dos fármacos , Haemophilus parainfluenzae/efeitos dos fármacos , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Testes de Sensibilidade Microbiana , Mutação , Regiões Promotoras Genéticas , Combinação Trimetoprima e Sulfametoxazol/farmacologia , Sequenciamento Completo do Genoma
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