A multi-drug resistant Salmonella Typhimurium ST213 human-invasive strain (33676) containing the blaCMY-2 gene on an IncF plasmid is attenuated for virulence in BALB/c mice

BMC Microbiology

Research Article

Marcos Fernández-Mora¹  Claudia Silva¹  Edmundo Calva¹  Víctor H. Bustamante¹  Deyanira Pérez-Morales¹  Magdalena Wiesner²  Juan J. Calva³ 

[1] Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, Mexico;Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, Mexico;Present address: Grupo de Microbiología, Dirección de Investigación en Salud Pública, Instituto Nacional de Salud, Bogotá, Colombia;Department of Infectious Diseases, Instituto Nacional de Ciencias Médicas y Nutrición “Salvador Zubirán”, México City, Mexico;

关键词: Bacterial pathogenesis;    Antimicrobial resistance;    Multilocus sequence typing MLST;    Salmonella;    Bacterial conjugation;    IncA/C plasmid;    IncF plasmid;    ColE1-like plasmid;    Plasmid co-integration;    Salmonella;   

DOI  :  10.1186/s12866-016-0633-7

 received in 2015-10-16, accepted in 2016-01-30,  发布年份 2016

来源: Springer

【 摘 要 】

BackgroundClassical strains of Salmonella enterica serovar Typhimurium (Typhimurium) predominantly cause a self-limiting diarrheal illness in humans and a systemic disease in mice. In this study, we report the characterization of a strain isolated from a blood-culture taken from a 15-year old woman suffering from invasive severe salmonellosis, refractory to conventional therapy with extended-spectrum cephalosporin (ESC).ResultsThe strain, named 33676, was characterized as multidrug-resistant Salmonella serogroup A by biochemical, antimicrobial and serological tests. Multilocus sequence typing (MLST) and XbaI macrorestrictions (PFGE) showed that strain 33676 belonged to the Typhimurium ST213 genotype, previously described for other Mexican Typhimurium strains. PCR analyses revealed the presence of IncA/C, IncFIIA and ColE1-like plasmids and the absence of the Salmonella virulence plasmid (pSTV). Conjugation assays showed that the ESC-resistance gene blaCMY-2 was carried on the conjugative IncF plasmid, instead of the IncA/C plasmid, as found in previously studied ST213 strains. Although the IncA/C plasmid conferred most of the observed antimicrobial resistances it was not self-conjugative; it was rather able to conjugate by co-integrating with the IncF plasmid. Strain 33676 was fully attenuated for virulence in BALB/c mice infections. Both type-three secretion system (T3SS), encoded in Salmonella pathogenicity islands 1 and 2 (SPI-1 and SPI-2), were functional in the 33676 strain and, interestingly, this strain produced the H2 FljB flagellin instead of the H1 FliC flagellin commonly expressed by S. enterica strains.ConclusionsStrain 33676 showed two main features that differentiate it from the originally described ST213 strains: 1) the blaCMY-2 gene was not carried on the IncA/C plasmid, but on a conjugative IncF plasmid, which may open a new route of dissemination for this ESC-resistance gene, and 2) it expresses the H2 FljB flagella, in contrast with the other ST213 and most Typhimurium reference strains. To our knowledge this is the first report of an IncF blaCMY-2-carrying plasmid in Salmonella.

【 授权许可】

CC BY   
© Wiesner et al. 2016