Efficacy of biofilm disrupters against Candida auris and other Candida species in monomicrobial and polymicrobial biofilms.

Candida species are now considered global threats by the CDC and WHO. Candida auris specifically is on the critical pathogen threat list along with Candida albicans. In addition, it is not uncommon to find Candida spp. in a mixed culture with bacterial organisms, especially Staphylococcus aureus producing polymicrobial infections. To eradicate these organisms from the environment and from patient surfaces, surface agents such as chlorhexidine (CHD) and Puracyn are used. Biofilm disrupters (BDs) are novel agents with a broad spectrum of antimicrobial activity and have been used in the management of chronic wounds and to sterilise environmental surfaces for the past several years. The goal of this study was to evaluate BDs (BlastX, Torrent, NSSD) and CHD against Candida spp. and S. aureus using zone of inhibition assays, biofilm and time-kill assays. All BDs and CHD inhibited C. auris growth effectively in a concentration-dependent manner. Additionally, CHD and the BDs showed excellent antimicrobial activity within polymicrobial biofilms. A comparative analysis of the BDs and CHD against C. auris and C. albicans using biofilm kill-curves showed at least 99.999% killing. All three BDs and CHD have excellent activity against different Candida species, including C. auris. However, one isolate of C. auris in a polymicrobial biofilm assay showed resistance/tolerance to CHD, but not to the BDs. The fungicidal activity of these novel agents will be valuable in eradicating surface colonisation of Candida spp, especially C. auris from colonised environmental surfaces and from wounds in colonised patients.

The Campylobacter jejuni Response Regulator and Cyclic-Di-GMP Binding CbrR Is a Novel Regulator of Flagellar Motility.

A leading cause of bacterial gastroenteritis, Campylobacter jejuni is also associated with broad sequelae, including extragastrointestinal conditions such as reactive arthritis and Guillain-Barré Syndrome (GBS). CbrR is a C. jejuni response regulator that is annotated as a diguanylate cyclase (DGC), an enzyme that catalyzes the synthesis of c-di-GMP, a universal bacterial second messenger, from GTP. In C. jejuni DRH212, we constructed an unmarked deletion mutant, cbrR-, and complemented mutant, cbrR+. Motility assays indicated a hyper-motile phenotype associated with cbrR-, whereas motility was deficient in cbrR+. The overexpression of CbrR in cbrR+ was accompanied by a reduction in expression of FlaA, the major flagellin. Biofilm assays and scanning electron microscopy demonstrated similarities between DRH212 and cbrR-; however, cbrR+ was unable to form significant biofilms. Transmission electron microscopy showed similar cell morphology between the three strains; however, cbrR+ cells lacked flagella. Differential radial capillary action of ligand assays (DRaCALA) showed that CbrR binds GTP and c-di-GMP. Liquid chromatography tandem mass spectrometry detected low levels of c-di-GMP in C. jejuni and in E. coli expressing CbrR. CbrR is therefore a negative regulator of FlaA expression and motility, a critical virulence factor in C. jejuni pathogenesis.

Binding of Campylobacter jejuni FliW Adjacent to the CsrA RNA-Binding Pockets Modulates CsrA Regulatory Activity.

Campylobacter jejuni CsrA is an mRNA-binding, post-transcriptional regulator that controls many metabolic- and virulence-related characteristics of this important pathogen. In contrast to E. coli CsrA, whose activity is modulated by binding to small non-coding RNAs (sRNAs), C. jejuni CsrA activity is controlled by binding to the CsrA antagonist FliW. In this study, we identified the FliW binding site on CsrA. Deletion of the C-terminus of C. jejuni CsrA, which is extended relative to sRNA-binding CsrA proteins, abrogated FliW binding. Bacterial two-hybrid experiments were used to assess the interaction of FliW with wild-type CsrA and mutants thereof, in which every amino acid was individually mutated. Two CsrA mutations (V51A and N55A) resulted in a significant decrease in FliW binding. The V51A and N55A mutants also showed a decrease in CsrA-FliW complex formation, as assessed by size-exclusion chromatography and surface plasmon resonance. These residues were highly conserved in bacterial species containing CsrA orthologs whose activities are predicted to be regulated by FliW. The location of FliW binding was immediately adjacent to the two RNA-binding sites of the CsrA homodimer, suggesting the model that FliW binding to CsrA modulates its ability to bind to its mRNA targets either by steric hindrance, electrostatic repulsion, or by altering the overall structure of the RNA-binding sites.

Psychotropic Drug Prescription and the Risk of Falls in Nursing Home Residents.

BACKGROUND: Falling is a common and serious problem in the elderly. Previous studies suggest that the use of psychotropic drugs increases the risk of falling. However, the contribution of these drugs on fall risk has not been quantified on a daily basis among the general population of nursing homes until now. OBJECTIVE: To assess the association between fall incidence and the prescription of psychotropic drugs and different categories of psychotropic drugs (antipsychotics, antidepressants, and benzodiazepines) among a general nursing home population. DESIGN: Retrospective observational study, data collection per person-day. SETTING: 9 nursing homes in Eindhoven, the Netherlands. PARTICIPANTS: 2368 nursing home residents, resulting in 538,575 person-days. MAIN OUTCOME MEASURE: Association between the prescription of psychotropic drugs and falls. RESULTS: A total of 2368 nursing home residents were included, which resulted in a data set of 538,575 person-days. Prescription of at least 1 psychotropic drug per day occurred during a total of 318,128 person-days (59.1%). Scheduled prescriptions with or without an as-needed prescription were involved in a total of 270,781 person-days (50.3%). The prescription of psychotropic drugs on a scheduled basis was found to be associated with almost a 3-fold increase in fall incidence (OR 2.88; 95% CI 1.52-5.44). An increase in fall incidence was found following the prescription of antipsychotics (OR 1.97; 95% CI 1.51-2.59) and antidepressants (OR 2.26; 95% CI 1.73-2.95). This increased fall risk was found for prescriptions on a scheduled basis as well as for prescriptions on an as-needed basis. CONCLUSION: The prescription of psychotropic drugs is associated with a strongly increased risk of falling among nursing home residents. To our knowledge, this is the first study among the general nursing home population in which the association between daily falls and daily prescriptions of psychotropic drugs and groups of psychotropic drugs was specified.