Genetic analysis of vancomycin-variable Enterococcus faecium clinical isolates in Italy.
Eur J Clin Microbiol Infect Dis
; 43(4): 673-682, 2024 Apr.
Article
em En
| MEDLINE
| ID: mdl-38296911
ABSTRACT
PURPOSE:
To investigate the occurrence of vancomycin-variable enterococci (VVE) in a hospital in central Italy.METHODS:
vanA positive but vancomycin-susceptible Enterococcus faecium isolates (VVE-S) were characterized by antibiotic susceptibility tests, molecular typing (PFGE and MLST), and WGS approach. The reversion of VVE-S to a resistant phenotype was assessed by exposure to increasing vancomycin concentrations, and the revertant isolates were used in filter mating experiments. qPCR was used to analyze the plasmid copy number.RESULTS:
Eleven putative VVE-S were selected. WGS revealed two categories of vanA cluster plasmid located the first type showed the lack of vanR, the deletion of vanS, and an intact vanH/vanA/vanX cluster; the second type was devoid of both vanR and vanS and showed a deletion of 544-bp at the 5'-end of the vanH. Strains (n = 7) carrying the first type of vanA cluster were considered VVE-S and were able to regain a resistance phenotype (VVE-R) in the presence of vancomycin, due to a 44-bp deletion in the promoter region of vanH/vanA/vanX, causing its constitutive expression. VVE-R strains were not able to transfer resistance by conjugation, and the resistance phenotype was unstable after 11 days of growth without selective pressure, the revertants were still resistant but showed a lower vancomycin MIC. A higher plasmid copy number in the revertant strains was probably related to the resistance phenotype.CONCLUSION:
We highlight the importance of VVE transition to VRE under vancomycin therapy resulting in a potential failure treatment. We also report the first-time identification of VVE-S isolates pstS-null belonging to ST1478.Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Infecções por Bactérias Gram-Positivas
/
Enterococcus faecium
Tipo de estudo:
Prognostic_studies
Limite:
Humans
Idioma:
En
Revista:
Eur J Clin Microbiol Infect Dis
Assunto da revista:
DOENCAS TRANSMISSIVEIS
/
MICROBIOLOGIA
Ano de publicação:
2024
Tipo de documento:
Article
País de afiliação:
Itália