Chlorhexidine activity against bacterial biofilms

Many orthopedic surgeons consider surgical irrigation and debridement with prosthesis retention as a treatment option for postoperative infections. Usually, saline solution with no added antimicrobial agent is used for irrigation. We investigated the activity of N-chlorotaurine (NCT) against various biofilm-forming bacteria in vitro and thereby gained significant information on its usability as a soluble and well-tolerated active chlorine compound in orthopedic surgery. Biofilms of Staphylococcus aureus were grown on metal alloy disks and in polystyrene dishes for 48 h. Subsequently, they were incubated for 15 min to 7 h in buffered solutions containing therapeutically applicable concentrations of NCT (1%, 0.5%, and 0.1%; 5.5 to 55 mM) at 37°C. NCT inactivated the biofilm in a time-and dose-dependent manner. Scanning electron microscopy revealed disturbance of the biofilm architecture by rupture of the extracellular matrix. Assays with reduction of carboxanilide (XTT) showed inhibition of the metabolism of the bacteria in biofilms. Quantitative cultures confirmed killing of S. aureus, Staphylococcus epidermidis, and Pseudomonas aeruginosa biofilms on metal alloy disks by NCT. Clinical isolates were slightly more resistant than ATCC type strains, but counts of CFU were reduced at least 10-fold by 1% NCT within 15 min in all cases. NCT showed microbicidal activity against various bacterial strains in biofilms. Whether this can be transferred to the clinical situation should be the aim of future studies.

Section: Discussionsupporting

confidence: 79%

Bactericidal Activity of N -Chlorotaurine against Biofilm-Forming Bacteria Grown on Metal Disks

Coraça‐Huber

Ammann

Fille

et al. 2014

“…Most of the currently available antifungals and antibiotics are unable to cure these biofilm-associated infections effectively (11,12). Therefore, treatment often requires the removal of the infected device, which can be an expensive and painful surgical procedure.…”

mentioning

confidence: 99%

Derivatives of the Mouse Cathelicidin-Related Antimicrobial Peptide (CRAMP) Inhibit Fungal and Bacterial Biofilm Formation

Brucker

Delattin

Robijns

et al. 2014

fWe identified a 26-amino-acid truncated form of the 34-amino-acid cathelicidin-related antimicrobial peptide (CRAMP) in the islets of Langerhans of the murine pancreas. This peptide, P318, shares 67% identity with the LL-37 human antimicrobial peptide. As LL-37 displays antimicrobial and antibiofilm activity, we tested antifungal and antibiofilm activity of P318 against the fungal pathogen Candida albicans. P318 shows biofilm-specific activity as it inhibits C. albicans biofilm formation at 0.15 M without affecting planktonic survival at that concentration. Next, we tested the C. albicans biofilm-inhibitory activity of a series of truncated and alanine-substituted derivatives of P318. Based on the biofilm-inhibitory activity of these derivatives and the length of the peptides, we decided to synthesize the shortened alanine-substituted peptide at position 10 (AS10; KLKKIAQKIKN FFQKLVP). AS10 inhibited C. albicans biofilm formation at 0.22 M and acted synergistically with amphotericin B and caspofungin against mature biofilms. AS10 also inhibited biofilm formation of different bacteria as well as of fungi and bacteria in a mixed biofilm. In addition, AS10 does not affect the viability or functionality of different cell types involved in osseointegration of an implant, pointing to the potential of AS10 for further development as a lead peptide to coat implants.

“…The percentages of microbicide solutions used in our experiments corresponded to the Centers for Disease Control and Prevention recommendations (29) (e.g., 0.1 to 2% CT and 0.05 to 1% CHX) for disinfection of hard surfaces such as SSWs. Similar percentages of microbicide solutions were recently used effectively against biofilms formed by periodontal pathogens (30)(31)(32) and single strains of relevant Gram-positive and Gram-negative pathogens, including A. baumannii (33). Interestingly, A. baumannii biofilm-associated cells have shown resistance to CHX, but effective concentrations used to kill these bacterial cells are comparable to those used in this study (33).…”

Section: Discussionmentioning

confidence: 90%

“…Similar percentages of microbicide solutions were recently used effectively against biofilms formed by periodontal pathogens (30)(31)(32) and single strains of relevant Gram-positive and Gram-negative pathogens, including A. baumannii (33). Interestingly, A. baumannii biofilm-associated cells have shown resistance to CHX, but effective concentrations used to kill these bacterial cells are comparable to those used in this study (33). Furthermore, CHX has been effectively combined with other antimicrobials to coat central venous catheters to prevent biofilm colonization by Gram-negative bacteria (34).…”

Section: Discussionmentioning

confidence: 99%

Microbicides Alter the Expression and Function of RND-Type Efflux Pump AdeABC in Biofilm-Associated Cells of Acinetobacter baumannii Clinical Isolates

Krishnamoorthy

Shah

Lee

et al. 2016

Acinetobacter baumannii is a Gram-negative bacterium that causes nosocomial infections worldwide. This microbe's propensity to form biofilms allows it to persist and to survive on clinical abiotic surfaces for long periods. In fact, A. baumannii biofilm formation and its multidrug-resistant nature severely compromise our capacity to care for patients in hospital environments. In contrast, microbicides such as cetrimide (CT) and chlorhexidine (CHX) play important roles in the prevention and treatment of infections. We assessed the efficacy of CT and CHX, either alone or in combination, in eradicating A. baumannii biofilms formed by clinical isolates, by using stainless steel washers to mimic hard abiotic surfaces found in hospital settings. We demonstrated that increasing amounts of each microbicide, alone or in combination, were able to damage and to reduce the viability of A. baumannii biofilms efficaciously. Interestingly, the adeB gene of the resistance-nodulation-cell division (RND) family is predominantly associated with acquired resistance to antimicrobials in A. baumannii. We showed that CT and CHX adversely modified the expression and function of the RND-type efflux pump AdeABC in biofilm-associated A. baumannii cells. Furthermore, we established that these microbicides decreased the negative charges on A. baumannii cell membranes, causing dysregulation of the efflux pump and leading to cell death. Our findings suggest that CT and CHX, alone or in combination, can be used efficaciously for eradication of A. baumannii from hospital surfaces, in order to reduce infections caused by this nosocomial agent.