Resistance to disinfectants is well investigated in staphylococci and pseudomonads but nearly unexplored in bacteria of the genus Enterococcus , despite their rising significance as nosocomial pathogens. In this study, Enterococcus faecalis ( n =585) from blood ( n =42) and stool ( n =109) of hospitalized humans, from faeces of farm animals ( n =226), and from food (milk and dairy products, n =96; meat and meat products, n =112) were screened for the presence of qac -genes ( qac A, qac B, qac C, smr [ qac C+ qac D], qac EΔ1, qac G, qac H, qac J) via PCR. The isolates' susceptibility to a quaternary ammonium compound (didecyldimethylammoniumchloride, DDAC) and antibiotics was assessed by microdilution. Four E. faecalis strains were positive for qac -genes: qac A/B was found in one isolate from cattle and one isolate from human blood; smr ( qac C+ qac D) was detected in one isolate from human stool and in one isolate from cheese (“Camembert”). The sequences of the qac A/B-amplicons differed in two basepairs. DDAC had an elevated minimum inhibitory concentration (MIC) of 2.45–3.5 mg/L in one qac A/B-positive strain from human blood, whereas the other qac -gene carriers had wild-type MIC-values for DDAC (1.05 mg/L). This is the first detection of qac A/B in the genus Enterococcus .

A multidrug efflux pump specified by the smr gene mediates low-level antiseptic resistance in staphylococci. We analyzed the genomic diversity of smr and its gene cassette, a structural unit containing smr and terminal direct repeats (DRs), in 22 clinical strains of Staphylococcus aureus isolated over 9 years in a Japanese hospital. Although open reading frames (ORFs) of all the smr genes examined were identical to those reported previously (e.g., qacD in pSK41), smr gene cassettes were classified into three groups (types 1, 2, and 3). The type 1 cassette had an identical genetic organization to that found in the plasmid pSK41, a putative prototype of the smr gene cassette, which contains DRs flanking smr . In the type 2 cassette, the rep gene and a putative replication nick site were found upstream of smr , between a SSO A (single-strand origin) sequence and DR1 c , which are components of the type 1 cassette DR. In the type 3 cassette detected in a single strain, IS 431 was located between the 3′ end of smr and DR. It was suggested by genomic comparison that type 2 and type 3 cassettes might have been derived from the type 1 cassette via insertion of foreign DNA sequence, and that the type 2 cassette might be a precursor form of some previously reported smr cassettes, such as those in pSK108 and pNVH99. Although MICs of antiseptics and ethidium bromide were generally the same among strains having type 1, 2, or 3 smr gene cassette, the type 1 cassette was detected most frequently. Moreover, the copy number of the smr gene in the type 2 cassette was found to be much higher than that in the type 1 or type 3 cassette.

Candidozyma (formerly Candida) auris (C. auris), a WHO critical priority pathogen known for its multi-drug resistance and strong skin tropism, is posing a significant health threat. This study evaluates the efficacy of commercial octenidine-based antiseptics in reducing C. auris colonisation on intact and wounded human skin. Using an established ex vivo human skin model to simulate clinical settings, skin samples from healthy donors were exposed to planktonic C. auris cells. Six hours post-contamination, two ready-to-use octenidine-based antiseptics were applied, and fungal colonisation was assessed after 18 h via periodic acid-Schiff staining, bright field and scanning electron microscopy and colony forming unit quantification. In vitro biofilm assays with various C. auris strains, including drug resistant ones, were performed to determine the antifungal effects of octenidine formulations. Results showed that octenidine-based antiseptics significantly reduced C. auris viability on intact and wounded human skin, and also demonstrated a nearly complete eradication across tested strains in vitro. These findings highlight the potential of octenidine-based products in reducing C. auris colonisation, supporting infection prevention and control strategies in healthcare settings and enhancing patient safety.

The growing antibiotic resistance of microorganisms causing postoperative infections following orthopedic surgeries underscores the urgent need for localized antiseptic and lavage delivery systems to enhance infection control. This study evaluates the in vitro effectiveness of antiseptic and lavage solutions-including polyhexanide, povidone-iodine, low-concentrated hypochlorite, Ringer's solution, and saline-against <i>Staphylococcus epidermidis</i>, <i>Staphylococcus aureus</i> MRSA, <i>Cutibacterium acnes</i>, <i>Corynebacterium amycolatum</i>, <i>Pseudomonas aeruginosa</i>, and <i>Candida albicans</i>. Using microplate models (Minimum Inhibitory Concentration, Minimum Biofilm Eradication Concentration, and Biofilm-Oriented Antiseptic Test assays), flow-based models (Bioflux system), and surfaces relevant to orthopedic implants (e.g., stainless steel disks/screws, Co-Cr-Mo, Ti-Al-Nb orthopedic alloys, and ultra-high-molecular-weight polyethylene), as well as a bio-nano-cellulose scaffold representing tissue, we assessed the solutions' activity. The cytotoxicity of the solutions was evaluated using osteoblast and keratinocyte cell lines, with additional in vivo insights gained through the <i>Galleria mellonella</i> larval model. The results show that polyhexanide-based solutions outperformed povidone-iodine in biofilm eradication in most tests applied, particularly on complex surfaces, whereas iodine demonstrated higher cytotoxicity in applied in vitro and in vivo tests. Low-concentration hypochlorite solutions exhibited minimal antibiofilm activity but also showed no cytotoxicity in cell line and <i>G. mellonella</i> larval models. These findings highlight the importance of careful antiseptic selection and rinsing protocols to balance infection control efficacy with tissue compatibility in orthopedic applications.

Biofilms are a key driver of chronicity and treatment failure in diabetic foot ulcers (DFUs), yet clinical evidence quantifying their impact and management remains fragmented. This systematic narrative review synthesised recent evidence (2015-2025) on the prevalence, diagnostics, and management of biofilm in DFUs. A Systematic Review of the Literature (SRL) was conducted following PRISMA 2020 guidelines across PubMed/MEDLINE, Scopus, Cochrane Library and ScienceDirect. Eligible studies included adults with DFUs reporting biofilm/bioburden metrics or interventions aimed at biofilm disruption. Risk of bias was assessed using RoB 2 for randomised trials and ROBINS-I for non-randomised studies. Data were narratively synthesised by evidence tier (Tier 1 = clinical; Tier 2 = preclinical/mechanistic). Of 600 records screened, 25 studies met inclusion criteria (Tier 1 n = 9; Tier 2 n = 5; reviews n = 11). Over half of bacterial isolates in DFUs were biofilm producers, with multidrug resistance exceeding 90% in several cohorts. Fungi were detected in 31% of ulcers by qPCR but only 9% by culture. Tier 1 clinical evidence supports standard care components-debridement, antiseptics, and negative-pressure wound therapy-for improved healing, though direct antibiofilm outcomes remain limited. Emerging strategies (enzymatic agents, peptides, cold plasma, smart dressings) show promise in vitro but lack clinical translation. Evidence for direct antibiofilm efficacy in DFUs remains scarce. Current data justify maintaining guideline-based care while prioritising trials that integrate validated biofilm endpoints, standardised microbiological methods, and antifungal components. Distinguishing established from experimental approaches is essential to advancing safe, evidence-based biofilm management in DFUs.

Surgical site infections (SSIs) and prosthetic joint infections (PJIs) remain significant challenges in orthopedic surgery, particularly in joint arthroplasty. Intraoperative irrigation is a widely used strategy for infection prevention, yet traditional solutions such as saline, povidone-iodine, hydrogen peroxide, and sodium hypochlorite are limited by cytotoxicity, short antimicrobial duration, and poor biofilm penetration. This review evaluates commonly used irrigation agents and highlights the growing evidence supporting a novel citrate-based solution as a potentially superior alternative. These agents combine broad-spectrum antimicrobial activity, effective biofilm disruption through ionic chelation, and prolonged postoperative protection with minimal harm to host tissues. Early clinical studies and ongoing randomized trials have demonstrated promising results, including reductions in postoperative swelling, opioid use, and infection rates. As more data become available, citrate-based solutions may emerge as the preferred standard for intraoperative irrigation in orthopedic procedures.

<h4>Background and objective</h4>The emergence of antimicrobial resistance (AMR) poses a significant global health threat, with developing countries such as the Philippines facing particularly severe impacts due to resource limitations. The most affected by AMR is Healthcare Acquired Infections (HAIs), including Catheter-Related Bloodstream Infections (CRBSIs). These are commonly associated with biofilm-forming bacteria like <i>Staphylococcus epidermidis</i>, which complicates treatment due to antibiotic resistance. The Philippine variety of <i>Psidium guajava</i>, a folklorically used medicinal plant, has shown potential antimicrobial properties that could offer a new avenue for combating resistant pathogens.<h4>Methods</h4>This study evaluated the antibacterial and antibiofilm efficacy of crude <i>Psidium guajava</i> ethanolic leaf extracts (PGELE) against biofilm-forming <i>S. epidermidis</i> (ATCC 12228). PGELE was tested at five concentrations (ranging from 312.5 µg/mL to 10,000 µg/mL) using two-fold serial dilution to determine the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) using agar dilution count method. For the Minimum Biofilm Inhibitory Concentration (MBIC) and Minimum Biofilm Eradication Concentration (MBEC), crude PGELE was tested at 0.25 x MIC, 0.5 x MIC, MIC, 2 x MIC and 4 x MIC.<h4>Results</h4>The MIC for PGELE against <i>S. epidermidis</i> was determined to be 2500 µg/mL, and the MBC was 5000 µg/mL, indicating that PGELE exhibits bactericidal activity. In biofilm assays, PGELE demonstrated strong antibiofilm activity at concentrations as low as 625 µg/mL, inhibiting biofilm formation by more than 50%. However, PGELE did not eradicate preformed biofilms, as indicated by the MBEC results at concentrations ranging from 625 µg/mL to 10,000 µg/mL.<h4>Conclusion</h4><i>Psidium guajava</i> ethanolic leaf extracts exhibit antibacterial and antibiofilm activities against <i>S. epidermidis</i>, particularly in preventing biofilm formation. These findings suggest that PGELE could be developed as an effective natural antimicrobial agent for use in healthcare settings to prevent CRBSIs and other infections caused by biofilm-forming pathogens. Further research and development are warranted to explore the potential of PGELE for antimicrobial drug development.

<h4>Background</h4>Diabetic foot ulcers (DFUs) are a prevalent and severe complication of diabetes, leading to significant morbidity, impaired health-related quality of life (HRQoL) and economic burden on healthcare systems. The complexity of DFUs often results in prolonged healing and high recurrence rates. Effective management strategies are crucial for improving outcomes and reducing complications.<h4>Aim</h4>This study aimed to review the efficacy of antiseptic solutions in the treatment and care of DFUs.<h4>Method</h4>A literature analysis was conducted to review clinical studies and guidelines on the use and efficacy of antiseptic solutions, particularly Octenisept^® (0.1% octenidine dihydrochloride and 2% 2-phenoxyethanol). The review focused on the antimicrobial properties, biofilm-disruption capabilities and wound healing outcomes associated with the use of antiseptic solutions in DFU management.<h4>Results</h4>Antiseptic solutions have potential to reduce bioburden, disrupt biofilm and modulate healing. There is a need to balance antimicrobial clinical efficacy with tolerability and cytotoxicity. The use and choice of adjunctive antiseptic solutions must be tailored to the patient, as antimicrobial efficacy can vary for antiseptic solutions, particularly for hypochlorous solutions. It is important to use products according to their instructions, with consideration of minimum contact time to maximise clinical efficacy. Low-pressure irrigation is adjunctive, and concurrent wound-bed preparation, including debridement, frequent inspection, infection and moisture control, remain important.<h4>Conclusions</h4>The therapeutic application of antiseptic solutions in DFU care presents a promising approach to enhancing wound healing and reducing infection risks. Integrating these solutions into standard wound care protocols could lower the incidence of complications, improve HRQoL and decrease the economic burden associated with diabetic foot disease. Further large-scale studies are recommended to validate these findings and refine guidelines for antiseptic use in DFU management.

Effect of growth-rate on resistance of gram-negative biofilms to cetrimide. A method of cell culture, which allows control of growth rate for sessile Gram-negative populations, has been employed to assess the sensitivity of Escherichia coli biofilms to the antiseptic compound, cetrimide. Growth-rate-dependent changes in sensitivity were compared for chemostat-grown, planktonic cells, for cells resuspended from the biofilm and also for newly formed daughter cells shed from the biofilm during its growth and development. Susceptibility to cetrimide decreased in all instances with increases in growth-rate up to mu = 0.15 h-1. As growth rate was increased beyond this value then sensitivity increased in proportion to the rate of division. At rates of growth less than mu = 0.15 h-1 the susceptibility of the biofilm-derived cells and their offspring was significantly less than that of cells of planktonic origin. Published in The Journal of antimicrobial chemotherapy (1990)

In Vitro Evaluation of Polihexanide, Octenidine and NaClO/HClO-Based Antiseptics against Biofilm Formed by Wound Pathogens Chronic wounds complicated with biofilm formed by pathogens remain one of the most significant challenges of contemporary medicine. The application of topical antiseptic solutions against wound biofilm has been gaining increasing interest among clinical practitioners and scientific researchers. This paper compares the activity of polyhexanide-, octenidine- and hypochlorite/hypochlorous acid-based antiseptics against biofilm formed by clinical strains of <i>Candida albicans, Staphylococcus aureus</i> and <i>Pseudomonas aeruginosa</i>. The analyses included both standard techniques utilizing polystyrene plates and self-designed biocellulose-based models in which a biofilm formed by pathogens was formed on an elastic, fibrinous surface covered with a fibroblast layer. The obtained results show high antibiofilm activity of polihexanide- and octenidine-based antiseptics and lack or weak antibiofilm activity of hypochlorite-based antiseptic of total chlorine content equal to 80 parts per million.

Activity of antiseptics against biofilms of mixed bacterial species growing on silicone surfaces. As part of a programme to establish the relative merits of antiseptics that are used as bladder instillations to control urinary tract infections in patients with indwelling catheters, the activity of five such formulations were tested against dense (10(9) cfu/cm2) mixed biofilms composed of Citrobacter diversus, Pseudomonas aeruginosa and Enterococcus faecalis growing on silicone discs. All three species were resistant to chlorhexidine (200 mg/l) and povidone-iodine (1% v/v) in the biofilm mode of growth, whereas these agents rapidly eliminated viable cells from urine suspensions of the mixed community. Lactic acid (1% v/v) produced a 1 log reduction of the biofilm population within 30 min of exposure. The mandelic acid (1% w/v) and mandelic acid (0.5% w/v)/lactic acid (0.5% v/v) mixture proved to be the most effective in eliminating the biofilm organisms. It is suggested that these latter solutions should now be tested for efficacy in bladder washouts against urinary tract infections in catheterized patients.

Activity of antiseptics against biofilms of mixed bacterial species growing on silicone surfaces. As part of a programme to establish the relative merits of antiseptics that are used as bladder instillations to control urinary tract infections in patients with indwelling catheters, the activity of five such formulations were tested against dense (10(9) cfu/cm2) mixed biofilms composed of Citrobacter diversus, Pseudomonas aeruginosa and Enterococcus faecalis growing on silicone discs. All three species were resistant to chlorhexidine (200 mg/l) and povidone-iodine (1% v/v) in the biofilm mode of growth, whereas these agents rapidly eliminated viable cells from urine suspensions of the mixed community. Lactic acid (1% v/v) produced a 1 log reduction of the biofilm population within 30 min of exposure. The mandelic acid (1% w/v) and mandelic acid (0.5% w/v)/lactic acid (0.5% v/v) mixture proved to be the most effective in eliminating the biofilm organisms. It is suggested that these latter solutions should now be tested for efficacy in bladder washouts against urinary tract infections in catheterized patients.

Chronic suppurative otitis media (CSOM) affects up to 330 million people globally and is one of the leading causes of pediatric hearing loss. Defined by a state of chronic infection in the middle ear in the setting of a tympanic membrane perforation, CSOM is traditionally most frequently associated with infection with Pseudomonas and Staphylococcus aureus species. The current therapeutic options for CSOM include medical therapy in the form of topical antibiotics or antiseptics (i.e., boric acid, acetic acid, povo-iodine), as well as surgical intervention with tympanoplasty or tympanomastoidectomy in refractory cases. While topical fluoroquinolones have the strongest level of evidence supporting their use for CSOM treatment, they are frequently associated with long-term treatment failure. Treatment failure is secondary to the presence of persister cells in CSOM, which are antibiotic tolerant and have the potential to proliferate and gain additional antibiotic resistance. As biofilms and persister cells are not routinely tested for in clinical medicine, there is limited data on therapeutic options that may eradicate biofilms and persister cells while limiting ototoxic effects. While future research should aim to identify such ototopical treatment options, clinicians may also consider surgical intervention earlier in patients with disease refractory to topical treatment to both minimize the risk of encouraging antibiotic resistance and to maximize the ability to debride the biofilm.

Activity of antiseptics against Escherichia coli growing as biofilms on silicone surfaces. The activity of chlorhexidine, acetic, lactic and mandelic acids were examined against biofilms of Escherichia coli established on silicone discs and against the test strain growing in suspension in urine. The results showed that the concentrations of chlorhexidine and acetic acid normally used for bladder instillations to control infections in patients with indwelling catheters failed to eliminate cells from the biofilm in exposure periods of up to 2 h. Lactic acid (1% v/v) had a bactericidal effect on planktonic cells but poor activity against cells in the biofilm. Mandelic acid (1% v/v), and mandelic (1% v/v) and lactic acid (1% v/v) mixtures eliminated organisms from both suspensions and biofilms. It is suggested that these solutions be considered as alternatives to acetic acid and chlorhexidine for the washing of catheterized bladders. Published in European journal of clinical microbiology & infectious diseases : official publication of the European Society of Clinical Microbiology (1989)

Activity of some antiseptics against urinary tract pathogens growing as biofilms on silicone surfaces. The activity of chlorhexidine, mandelic acid and a mandelic/lactic mixture were tested against biofilms of four species of gram-negative nosocomial organisms that commonly infect the catheterized urinary tract. Cells growing on silicone discs were exposed to concentrations of agents used in bladder instillation. Citrobacter diversus biofilms proved to be sensitive to all three agents. Pseudomonas aeruginosa, Proteus mirabilis and Klebsiella pneumoniae all survived well in chlorhexidine but their viability was significantly reduced by the mandelic acid formulations. These results suggest that bladder instillations of mandelic acid or mandelic/lactic acids would be more effective than chlorhexidine in eliminating biofilms from catheter surfaces. Published in European journal of clinical microbiology & infectious diseases : official publication of the European Society of Clinical Microbiology (1991)