In vitro selection of Staphylococcus aureus mutants resistant to tigecycline with intermediate susceptibility to vancomycin

Annals of Clinical Microbiology and Antimicrobials

Short Report

Melina Herrera¹  Graciela Posse¹  José Di Conza²  Sabrina Di Gregorio³  Marta Mollerach³  Silvina Fernandez³ 

[1] Facultad de Ciencias de la Salud, Universidad Adventista del Plata, 25 de mayo 99, Libertador San Martín, Entre Ríos, Argentina;Facultad de Ciencias de la Salud, Universidad Adventista del Plata, 25 de mayo 99, Libertador San Martín, Entre Ríos, Argentina;Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Junín 956, Ciudad Autónoma de Buenos Aires, Argentina;Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral, Ciudad Universitaria, Paraje “El Pozo”, CC 242, Santa Fe, Argentina;Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Junín 956, Ciudad Autónoma de Buenos Aires, Argentina;

关键词: MRSA;    Tigecycline resistant;    Efflux activity;    VISA;   

DOI  :  10.1186/s12941-016-0131-7

 received in 2015-10-22, accepted in 2016-02-29,  发布年份 2016

来源: Springer

【 摘 要 】

BackgroundTigecycline (TIG) is an antibiotic belonging to the glycylcyclines class and appears to be a good choice to fight infections caused by Staphylococcus aureus. To date, TIG exhibits good activity against this microorganism. The aim of this work was to obtain in vitro mutants of S. aureus resistant to TIG and evaluate possible changes in their susceptibility patterns to other antibiotics.ResultsTwo mutants of S. aureus resistant to TIG (MIC = 16 µg/mL) were selected in vitro from clinical isolates of methicillin-resistant S. aureus. In both mutants, corresponding to different lineage (ST5 and ST239), an increase of efflux activity against TIG was detected. One mutant also showed a reduced susceptibility to vancomycin, corresponding to the VISA phenotype (MIC = 4 µg/mL), with a loss of functionality of the agr locus. The emergence of the VISA phenotype was accompanied by an increase in oxacillin and cefoxitin MICs.ConclusionsThis study demonstrates that, under selective pressure, the increase of efflux activity in S. aureus is one of the mechanisms that may be involved in the emergence of tigecycline resistance. The emergence of this phenotype may eventually be associated to changes in susceptibility to other antibiotics such oxacillin and vancomycin.

【 授权许可】

CC BY   
© Herrera et al. 2016