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In vitro sensitivity study of isolates of multiresistant gram-negative bacteria

Grant number: 17/23340-2
Support Opportunities:Scholarships in Brazil - Scientific Initiation
Effective date (Start): February 01, 2018
Effective date (End): December 31, 2018
Field of knowledge:Health Sciences - Medicine - Medical Clinics
Principal Investigator:Silvia Figueiredo Costa
Grantee:Gaspar Camilo de Oliveira Pereira
Host Institution: Instituto de Medicina Tropical de São Paulo (IMT). Universidade de São Paulo (USP). São Paulo , SP, Brazil


Chlorhexidine digluconate (CHG) is currently used as topical antiseptic with bactericidal action against gram-positive and gram-negative microorganisms. In the last decade, chlorhexidine has been used in hospitals for antisepsis hand hygiene and other interventions to prevent infection related to health care (HAI). The expressive use of chlorhexidine led to the increase of gram-negative bacteria with minimal inhibitory concentration (MIC) for this antiseptic, among them: Klebsiella pneumoniae, Pseudomonas aeruginosa, Acinetobacter baumannii and Serratia marcescens. The mechanism of resistance is caused by the efflux pumps, encoded by the cepA, qacE and qacAE genes, located in the cytoplasmic membrane that expel chlorhexidine from the intracellular medium into the extracellular environment, hindering therapeutic actions against these microorganisms. The aim of the present study is evaluate the sensitivity of gram-negative bacteria to chlorhexidine, as well as the role of efflux pump is the use of the inhibitor carbonylcyanide m-chlorophenylhydrozone (CCCP), which has the capacity to reduce MIC by reducing efflux activity in microorganisms resistant to carbapenems and colistin. A total of 95 isolates previously sequenced by Illumina platform will be evaluated: 43 K. pneumoniae, 28 Acinetobacter baumannii, 16 Pseudomonas aeruginosa and 8 Serratia marcescens isolates,. The MIC for chlorhexidine with and without the CCCP will be evaluated by the agar dilution methods. The curation of genes related to efflux pump will be performed using bioinformatics methods. (AU)

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