期刊
JOURNAL OF ANTIMICROBIAL CHEMOTHERAPY
卷 69, 期 7, 页码 1815-1824出版社
OXFORD UNIV PRESS
DOI: 10.1093/jac/dku078
关键词
Salmonella Typhimurium; rdar morphotype; csgB; efflux; ramA
资金
- Spanish Ministry of Health [FIS 09/01174, FIS 11/02024]
- Departament d'Universitats, Recerca i Societat de la Informacio de la Generalitat de Catalunya [2009 SGR 1256]
- Ministerio de Sanidad y Consumo, Instituto de Salud Carlos III, Spanish Network for Research in Infectious Disease [REIPI 06/0008]
- European Community [HEALTH-F3-2008-223101]
- Barcelona Institute for Global Health (ISGlobal)
To investigate the potential relationship between quinolone resistance and biofilm production in a collection of Salmonella enterica clinical isolates and in S. enterica serovar Typhimurium serial mutants with increasing resistance to ciprofloxacin. Nalidixic acid susceptibility and biofilm formation were assessed in a collection of 122 S. enterica clinical isolates. An in vitro quinolone-resistant mutant, 59-64, was obtained from a biofilm-producing and quinolone-susceptible clinical isolate, 59-wt, in a multistep selection process after increasing ciprofloxacin concentrations. The quinolone resistance mechanisms [target gene and multidrug resistance (MDR) regulatory mutations, MICs of several antibiotics, cell envelope protein analysis, real-time PCR and ciprofloxacin accumulation] were characterized for mutant strains. In addition, analysis of fitness, biofilm formation, rdar morphotype and expression of biofilm-related genes by real-time PCR were also determined. Nalidixic acid-susceptible S. enterica strains were more prevalent in producing biofilm than the resistant counterparts. Strain 59-64 acquired five target gene mutations and showed an MDR phenotype. AcrAB and acrF overexpression were ruled out, whereas TolC did show increased expression in 59-64, which, in addition, accumulated less ciprofloxacin. Consistently, increased ramA expression was seen in 59-64 and attributed to a mutation within its promoter. Reduced biofilm production related to diminished csgB expression as well as reduced fitness was seen for 59-64, which was unable to form the rdar morphotype. Quinolone resistance acquisition may be associated with decreased production of biofilm due to lower csgB expression. Efflux, biofilm production and fitness seem to be interrelated.
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