Identification of mechanisms modulating chlorhexidine and octenidine susceptibility in Proteus mirabilis.

Aims: We aimed to identify mechanisms underlying the tolerance of Proteus mirabilis-a common cause of catheter associated urinary tract infection-to the clinically used biocides chlorhexidine (CHD) and octenidine (OCT).

Methods And Results: We adapted three clinical isolates to grow at concentrations of 512 µg ml-1 CHD and 128 µg ml-1 OCT. Genetic characterization and complementation studies revealed mutations inactivating the smvR repressor and increasing smvA efflux expression were associated with adaptation to both biocides.

Lipopolysaccharide structure modulates cationic biocide susceptibility and crystalline biofilm formation in .

Chlorhexidine (CHD) is a cationic biocide used ubiquitously in healthcare settings. , an important pathogen of the catheterized urinary tract, and isolates of this species are often described as "resistant" to CHD-containing products used for catheter infection control. To identify the mechanisms underlying reduced CHD susceptibility in , we subjected the CHD tolerant clinical isolate RS47 to random transposon mutagenesis and screened for mutants with reduced CHD minimum inhibitory concentrations (MICs).

De-repression of the efflux system arises in clinical isolates of and reduces susceptibility to chlorhexidine and other biocides.

is a common pathogen of the catheterised urinary tract and often described as intrinsically resistant to the biocide chlorhexidine (CHD). Here we demonstrate that de-repression of the efflux system has occurred in clinical isolates of and reduces susceptibility to CHD and other cationic biocides. Compared to other isolates examined, RS47 exhibited a significantly higher CHD MIC (≥512 μg/ml) and significantly greater expression of Comparison of the RS47 and cognate repressor with sequences from other isolates, indicated that RS47 encodes an inactivated Complementation of RS47 with a functional s from isolate RS50a (which exhibited the lowest expression and lowest CHD MIC) reduced expression by ∼59-fold, and markedly lowered the MIC of CHD and other cationic biocides.

An In Vitro Bladder Model for Studying Catheter-Associated Urinary Tract Infection and Associated Analysis of Biofilms.

Urethral catheters are among the most widely used medical devices, applied to manage a wide range of conditions in hospital, community, and care home settings. In long-term catheterized individuals, infection with Proteus mirabilis frequently complicates the care of patients owing to formation of extensive crystalline biofilms. Here we describe the use of an in vitro bladder model of the catheterized urinary tract and associated analyses to study P.

Bacterial biofilm formation on indwelling urethral catheters.

Urethral catheters are the most commonly deployed medical devices and used to manage a wide range of conditions in both hospital and community care settings. The use of long-term catheterization, where the catheter remains in place for a period >28 days remains common, and the care of these patients is often undermined by the acquisition of infections and formation of biofilms on catheter surfaces. Particular problems arise from colonization with urease-producing species such as Proteus mirabilis, which form unusual crystalline biofilms that encrust catheter surfaces and block urine flow.