ASSESSMENT OF CHLORHEXIDINE RESISTANCE IN PATHOGENIC BACTERIA ISOLATED FROM THE ORAL CAVITY OF HOSPITALISED PATIENTS
chlorhexidine; microbial drug resistance; mouth; microbiota; hospitalization
Research has shown that oral health deteriorates in hospitalised patients. The oral microbiota may suffer a shift in its composition during a period of hospitalisation, acquiring pathogenic microorganisms that would not normally be in the mouth. Chlorhexidine is an antiseptic often used for oral hygiene, as well as other uses in hospital settings. However, the potential development of microbial resistance to disinfectants and antiseptics such as chlorhexidine has been underestimated, despite the warning of recent studies about the development of resistance to the substance itself, the spread of cross-resistance to other antimicrobials, and the development of multidrug-resistant microorganisms. The aim of this study was to characterize oral health and the pathogenic non-oral microbiota present in the mouth of patients admitted to the Infirmary of the University Hospital of Brasilia, as well as to assess bacterial isolates in terms of susceptibility to chlorhexidine, susceptibility to antibacterial drugs and the possible change in resistance profile when associated in biofilms with a probiotic strain of Streptococcus salivarius. Hospitalised patients were examined by a dental surgeon and swabs of the oral mucosa were collected. The swabs were processed for the isolation of pathogenic microorganisms related to hospital-acquired infections. A minimum inhibitory concentration (MIC) test was carried out to determine the sensitivity of the bacterial isolates to chlorhexidine. Isolates with altered results were subjected to antibiograms in which various antibacterials were tested. Multidrug-resistant isolates were assessed for their chlorhexidine resistance profile in single biofilms or in association with S. salivarius. The prevalence of pathogenic microorganisms related to antimicrobial resistance was high in the patients examined. Of the isolates analysed, 28% had reduced sensitivity to chlorhexidine and some of them had MIC values much higher than those defined as the cut-off point for chlorhexidine resistance. Resistance of some isolates to certain antibacterials was observed and the association with S. salivarius in biofilms altered the chlorhexidine resistance profile of pathogenic.multidrug-resistant bacteria. The results show that the oral cavity can be a reservoir for pathogenic microorganisms that are multi-resistant to antibacterials and chlorhexidine, and that association in biofilms with bacteria from the oral microbiota such as S. salivarius can influence the process of resistance to antimicrobials and the selection of multiresistant microorganisms.