Antimicrobial Efficacy Testing Research Articles

Curcumin is effective in managing oral inflammation: An in vitro study.

Oral inflammation is among the most prevalent oral pathologies with systemic health implications, necessitating safe and effective treatments. Given curcumin's documented anti-inflammatory and antioxidant properties, this study focuses on the potential of a curcumin-based oral gel in safely managing oral inflammatory conditions. This in vitro study utilized four human cell lines: oral keratinocytes (HOKs), immortalized oral keratinocytes (OKF6), periodontal ligament fibroblasts (HPdLF), and dysplastic oral keratinocytes (DOKs). The cells were treated with Lipopolysaccharides (LPS) and curcumin-based oral gel to simulate inflammatory conditions. A panel of cellular assays were performed along with antimicrobial efficacy tests targeting Candida albicans, Streptococcus mutans, and Porphyromonas gingivalis. LPS significantly reduced proliferation and wound healing capacities of HOKs, OKF6, and HPdLF, but not DOKs. Treatment with curcumin-based oral gel mitigated inflammatory responses in HOKs and HPdLF by enhancing proliferation, colony formation, and wound healing, along with reducing apoptosis. However, its impact on OKF6 and DOKs was limited in some assays. Curcumin treatment did not affect the invasive capabilities of any cell line but did modulate cell adhesion in a cell line-specific manner. The curcumin-based oral gel showed significant antimicrobial efficacy against C. albicans and S. mutans, but was ineffective against P. gingivalis. This study demonstrates the potential of the curcumin-based oral gel as a safe and effective alternative to conventional antimicrobial treatments for managing cases of oral inflammation. This was achieved by modulating cellular responses under simulated inflammatory conditions. Future clinical-based studies are recommended to exploit curcumin's therapeutic benefits in oral healthcare.

An Investigation of the Antimicrobial Efficacy of a Nonwoven CMC PHMB Dressing and the Ability of the Dressing to Absorb Wound Slough

Objective. To conduct an in vitro investigation into the slough absorption and retention attributes of a gelling fiber dressing composed of CMC fibers and PHMB (Dressing A), and to assess its antimicrobial efficacy under compression. Materials and Methods. Dressing A is indicated for use with secondary dressings or bandaging, and conditions that replicate this compression element were applied. Dressing A was compared with 5 other dressings. Antimicrobial efficacy testing was conducted over a 7-day challenge period. Results. Dressing A absorbed an average of 33 g/100 cm2 per sample of viscous solution, 28% more than the other dressings tested. A greater than or equal to 6-log reduction of all microorganisms tested was achieved within 168 hours with Dressing A. Conclusion. The CMC PHMB gelling fiber dressing is able to absorb and retain viscous solutions (simulated slough). The antimicrobial efficacy of the dressing under compression was demonstrated by total eradication of all microorganisms tested.

Biocidal Verification Program for Healthcare Facilities: Evaluation of the Efficacy and Microbial Tolerance of Disinfectants

Context: The disinfection of healthcare facilities is of utmost importance to prevent the spread of infectious diseases. In this regard, biocidal activity testing is used to evaluate the efficacy of disinfectants in hospitals. Aim: Establishing a disinfectant efficacy test aimed at combating infections and cross-contamination. Settings and Design: The experiment was carried out in two treatment groups for each of the four microorganisms on ten surface coupons, with a viability control group determined as the baseline inoculum. Methods and Materials: The study used two disinfectants—hydroxyethane (ethylene hydrate) and 2-hydroxypropane (sec-propyl alcohol)—to evaluate their efficacy in reducing bacterial contamination on inanimate surfaces. Statistical analysis used: The data obtained was analyzed using Minitab software, which involved a normal probability plot, a homogeneity of variances test, and a test for equal variances. The statistical significance level was set at α = 0.05. Results: The normal probability plot of microorganism-disinfectant groups with a 95% confidence interval showed improvement in normalization after the logarithmic transformation of datasets. The homogeneity of variances test did not reveal any statistically significant differences between the groups, and all the comparison intervals overlapped for the logarithmically transformed datasets in contrast to the raw datasets. The bacterial reduction after exposure to disinfectants for five minutes compared with the control group in the surface challenge biocidal test expressed as absolute and logarithmic reduction showed a significant reduction in bacterial growth, with Burkholderia cepacia showing greater persistence on the examined sample of the surfaces. Conclusions: The current study showed that the effect of the microorganism tolerance contributed to the variation in responses rather than the disinfectant or the surface types, suggesting the risk of resistant bacteria on the contaminated surface in the dissemination of infections. Thus, monitoring and routine disinfection validation programs for the control of microbial burden in healthcare are crucial for infection and contamination mitigation

Sellado antibiótico de reservorios subcutáneos: estabilidad de soluciones con vancomicina

Subcutaneous reservoirs are a type of central venous catheter. When using central venous catheters, healthcare workers need to avoid two major risks: clot formation and bacterial infections. To prevent and avoid catheter contamination in both hospitalized patients and outpatients, several strategies have been carried out, such as the so-called ” antibiotic-based catheter lock solution”. Therefore, it has been suggested to implement the use of solutions with antimicrobial agents, to which anticoagulant and/or antibiofilm substances are often added. However, the stability of such solutions needs to be tested by techniques such as high performance liquid chromatography (HPLC), in addition to antimicrobial efficacy testing, in order to establish patient safety. In consequence, this literature review aims to include the most clinically representative research towards these aspects, to demonstrate the behaviour of antibiotic-based catheter lock solutions under different conditions of storage and use. In particular, this review focuses on solutions containing vancomycin. According to the studies consulted, vancomycin solutions with sodium citrate (chelating agent) present the best stability characteristics in terms of physicochemical properties and efficacy.. Keywords: Vancomycin; heparin; sodium citrate; stability; subcutaneous implantable central venous device

Microfluidic Giant Polymer Vesicles Equipped with Biopores for High-Throughput Screening of Bacteria.

Understanding the mechanisms of antibiotic resistance is critical for the development of new therapeutics. Traditional methods for testing bacteria are often limited in their efficiency and reusability. Single bacterial cells can be studied at high throughput using double emulsions, although the lack of control over the oil shell permeability and limited access to the droplet interior present serious drawbacks. Here, a straightforward strategy for studying bacteria-encapsulating double emulsion-templated giant unilamellar vesicles (GUVs) is introduced. This microfluidic approach serves to simultaneously load bacteria inside synthetic GUVs and to permeabilize their membrane with the pore-forming peptide melittin. This enables antibiotic delivery or the influx of fresh medium into the GUV lumen for highly parallel cultivation and antimicrobial efficacy testing. Polymer-based GUVs proved to be efficient culture and analysis microvessels, as microfluidics allow easy selection and encapsulation of bacteria and rapid modification of culture conditions for antibiotic development. Further, a method for in situ profiling of biofilms within GUVs for high-throughput screening is demonstrated. Conceivably, synthetic GUVs equipped with biopores can serve as a foundation for the high-throughput screening of bacterial colony interactions during biofilm formation and for investigating the effect of antibiotics on biofilms.

α,α-disubstituted β-amino amides eliminate Staphylococcus aureus biofilms by membrane disruption and biomass removal

Bacterial biofilms account for up to 80% of all infections and complicate successful therapies due to their intrinsic tolerance to antibiotics. Biofilms also cause serious problems in the industrial sectors, for instance due to the deterioration of metals or microbial contamination of products. Efforts are put in finding novel strategies in both avoiding and fighting biofilms. Biofilm control is achieved by killing and/or removing biofilm or preventing transition to the biofilm lifestyle. Previous research reported on the anti-biofilm potency of α,α-disubstituted β-amino amides A1, A2 and A3, which are small antimicrobial peptidomimetics with a molecular weight below 500 Da. In the current study it was investigated if these derivatives cause a fast disintegration of biofilm bacteria and removal of Staphylococcus aureus biofilms. One hour incubation of biofilms with all three derivatives resulted in reduced metabolic activity and membrane permeabilization in S. aureus (ATCC 25923) biofilms. Bactericidal properties of these derivatives were attributed to a direct effect on membranes of biofilm bacteria. The green fluorescence protein expressing Staphylococcus aureus strain AH2547 was cultivated in a CDC biofilm reactor and utilized for disinfectant efficacy testing of A3, following the single tube method (American Society for Testing and Materials designation number E2871). A3 at a concentration of 90 μM acted as fast as 100 μM chlorhexidine and was equally effective. Confocal laser scanning microscopy studies showed that chlorhexidine treatment lead to fluorescence fading indicating membrane permeabilization but did not cause biomass removal. In contrast, A3 treatment caused a simultaneous biofilm fluorescence loss and biomass removal. These dual anti-biofilm properties make α,α-disubstituted β-amino amides promising scaffolds in finding new control strategies against recalcitrant biofilms.

Evaluation of temperature, drying time and other determinants for the recovery of Gram-negative bacterial pathogens in disinfectant efficacy testing

In the clinical setting, surface disinfection is an important measure to reduce the risk of cross-transmission of microorganisms and the risk of nosocomial infections. Standardized methods can be used to evaluate said disinfection procedures, as well as the effectiveness of the active ingredients used for disinfection. However, despite standardization, the results of such methodologies are still determined by several factors and incorrect results may lead to invalid assumptions about the effectiveness of a disinfectant, posing significant health risks for patients and health personnel. The objective of this study was to evaluate several determinants for the recovery of Pseudomonas aeruginosa and other test organisms to establish their influence on the results of standardized disinfection methodologies and to find Gram-negative strains that could be used as suitable replacements of P. aeruginosa. The effects of inoculum application, drying times and temperatures as well as surface material on the survival and recovery of the test organisms were evaluated using Student-T test, one-way ANOVA and Tuckey's multiple comparison tests. Our results show that temperature and length of drying as well as application method and the material of germ carriers have significant effects on the recovery of P. aeruginosa cells and therefore influence the outcome of the methodologies used. This study also presents data showing that P. aeruginosa could be replaced with the Gram-negative species Acinetobacter baumannii, a test organism already in many standardized methodologies, which responds better under the same circumstances and has a behavior similar to that of P. aeruginosa in disinfectant efficacy tests.

An automated contact model for transmission of dry surface biofilms of Acinetobacter baumannii in healthcare

Dry surface biofilms (DSBs) have been recognized across environmental and equipment surfaces in hospitals and could explain how microbial contamination can survive for an extended period and may play a key role in the transmission of hospital-acquired infections. Despite little being known on how they form and proliferate in clinical settings, DSB models for disinfectant efficacy testing exist. In this study we develop a novel biofilm model to represent formation within hospitals, by emulating patient to surface interactions. The model generates a DSB through the transmission of artificial human sweat (AHS) and clinically relevant pathogens using a synthetic thumb capable of emulating human contact. The DNA, glycoconjugates and protein composition of the model biofilm, along with structural features of the micro-colonies was determined using fluorescent stains visualized by epifluorescence microscopy and compared with published clinical data. Micrographs revealed the heterogeneity of the biofilm across the surface; and reveal protein as the principal component within the matrix, followed by glycoconjugates and DNA. The model repeatably transferred trace amounts of micro-organisms and AHS, every 5min for up to 120h on to stainless-steel coupons to generate a biofilm model averaging 1.16× 103cfu/cm2 falling within the reported range for clinical DSB (4.20× 102 to 1.60× 107 bacteria/cm2). Our invitro DSB model exhibits many phenotypical characteristics and traits to those reported in situ. The model highlights key features often overlooked and the potential for downstream applications such as antibiofilm claims using more realistic microbial challenges.

Effectiveness and Durability of a Quaternary Ammonium Compounds-Based Surface Coating to Reduce Surface Contamination.

Foodborne diseases are of major concern as they have a significant impact on public health, both socially and economically. The occurrence of cross-contamination of food in household kitchens is a serious threat and the adoption of safe food practices is of paramount importance. This work aimed to study the effectiveness and durability of a commercial quaternary ammonium compound-based surface coating which, according to the manufacturer, retains its antimicrobial activity for 30 days, and is suitable for all types of hard surfaces for the prevention and/or control of cross-contamination. For that, its antimicrobial efficacy, killing contact time and durability on three different surfaces-polyvinyl chloride, glass, and stainless-steel-against three pathogens-Escherichia coli ATCC 25922, Acinetobacter baumannii ESB260 and Listeria monocytogenes Scott A-were tested according to the current antimicrobial treated surfaces efficacy test (ISO22196:2011). The results showed that the antimicrobial coating was effective against all pathogens with a reduction of >5.0 log CFU/cm2 in less than one minute for the three surfaces, but its durability was less than one week on all surfaces cleaned in the usual manner. Additionally, trace amounts (≤0.2 mg/kg) of the antimicrobial coating, which may migrate into food when contacting the surface, did not show cytotoxicity to human colorectal adenocarcinoma cells. The suggested antimicrobial coating has the potential to significantly reduce surface contamination, ensure surface disinfection and reduce the likelihood of cross-contamination in domestic kitchens, although it is less durable than suggested. The use of this technology in household settings is an attractive complement to the existing cleaning protocols and solutions that are already in place.

Hospital disinfectant efficacy testing: Experimental evidence towards the requirement of common international regulatory framework, the case of Costa Rica

Hospital disinfectant efficacy testing: Experimental evidence towards the requirement of common international regulatory framework, the case of Costa Rica

Evaluation of Biofilm Cultivation Models for Efficacy Testing of Disinfectants against Salmonella Typhimurium Biofilms

Within the European Union, Salmonella is frequently reported in food and feed products. A major route of transmission is upon contact with contaminated surfaces. In nature, bacteria such as Salmonella are often encountered in biofilms, where they are protected against antibiotics and disinfectants. Therefore, the removal and inactivation of biofilms is essential to ensure hygienic conditions. Currently, recommendations for disinfectant usage are based on results of efficacy testing against planktonic bacteria. There are no biofilm-specific standards for the efficacy testing of disinfectants against Salmonella. Here, we assessed three models for disinfectant efficacy testing on Salmonella Typhimurium biofilms. Achievable bacterial counts per biofilm, repeatability, and intra-laboratory reproducibility were analyzed. Biofilms of two Salmonella strains were grown on different surfaces and treated with glutaraldehyde or peracetic acid. Disinfectant efficacy was compared with results for planktonic Salmonella. All methods resulted in highly repeatable cell numbers per biofilm, with one assay showing variations of less than 1 log10 CFU in all experiments for both strains tested. Disinfectant concentrations required to inactivate biofilms were higher compared to planktonic cells. Differences were found between the biofilm methods regarding maximal achievable cell numbers, repeatability, and intra-laboratory reproducibility of results, which may be used to identify the most appropriate method in relation to application context. Developing a standardized protocol for testing disinfectant efficacy on biofilms will help identify conditions that are effective against biofilms.

Surrogate Selection for Foot-and-Mouth Disease Virus in Disinfectant Efficacy Tests by Simultaneous Comparison of Bacteriophage MS2 and Bovine Enterovirus Type 1.

In South Korea, testing disinfectants against foot-and-mouth disease virus (FMDV) that are contagious in livestock or that require special attention with respect to public hygiene can be manipulated only in high-level containment laboratories, which are not easily available. This causes difficulties in the approval procedure for disinfectants, such as a prolonged testing period. Additionally, the required biosafety level (BSL) in the case of FMDV has hindered its extensive studies. However, this drawback can be circumvented by using a surrogate virus to improve the performance of the efficacy testing procedure for disinfectants. Therefore, we studied bacteriophage MS2 (MS2) and bovine enterovirus type 1 (ECBO) with respect to disinfectant susceptibility for selecting a surrogate for FMDV according to the Animal and Plant Quarantine Agency (APQA) guidelines for efficacy testing of veterinary disinfectants. Effective concentrations of the active substances in disinfectants (potassium peroxymonosulfate, sodium dichloroisocyanurate, malic acid, citric acid, glutaraldehyde, and benzalkonium chloride) against FMDV, MS2, and ECBO were compared and, efficacies of eight APQA-listed commercial disinfectants used against FMDV were examined. The infectivity of FMDV and ECBO were confirmed by examination of cytopathic effects, and MS2 by plaque assay. The results reveal that the disinfectants are effective against MS2 and ECBO at higher concentrations than in FMDV, confirming their applicability as potential surrogates for FMDV in efficacy testing of veterinary disinfectants.

Composition of Challenge Substance in Standardized Antimicrobial Efficacy Testing of Wound Antimicrobials Is Essential to Correctly Simulate Efficacy in the Human Wound Micro-Environment.

Current standards insufficiently acknowledge the influence of the wound micro-environment on the efficacy of antimicrobial agents. To address this, octenidine/phenoxyethanol, polyhexanide, povidone-iodine, and sodium-hypochloride/hypochlorous acid solutions were submitted to standard-based (DIN-EN-13727) or modified peptide-based challenges and compared to a simulated clinical reference using human acute or chronic wound exudate (AWF/CWF). Antimicrobial efficacy against S. aureus and P. aeruginosa was compared using a quantitative suspension method. Agreement between methods were investigated using Bland-Altman (B&A) analysis. Different substances and challenges demonstrated diverging results, depending on class and concentration of agent and challenge. Highly concentrated antiseptics maintained a high efficacy under complex challenges, while especially chlorine-based irrigation solutions showed a remarkably reduced antimicrobial effect. Composition of challenge substance proved more relevant than pure concentration. Therefore, the current standard challenge conditions did not adequately reflect the wound micro-environment with over- or under-estimating antimicrobial efficacy, whilst the modified peptide-challenge showed a higher level of agreement with simulated realistic conditions (AWF/CWF). The results emphasize that a "one-fits-all" approach is not feasible to generalize antimicrobial efficacy, as certain aspects of the complex micro-environment pose a differing influence on varying agents. Based on these results, revision and target focused adaptation of the current standards should be considered.

Synthesis of the cyanobacterial halometabolite Chlorosphaerolactylate B and demonstration of its antimicrobial effect in vitro and in vivo.

Chlorosphaerolactylate B, a newly discovered antimicrobial halometabolite from the cyanobacterium Sphaerospermopsis sp. LEGE 00249 has been synthesized in three steps by using 12-bromododecanoic acid as starting material. A total of 0.5 g was produced for in vitro and in vivo antimicrobial efficacy testing. In vitro, the minimal inhibitory concentration (MIC) was estimated to be 256 mg/L for Staphylococcus aureus, while the minimal biofilm inhibitory concentration (MBIC) was estimated to be 74 mg/L. The in vivo study utilized a porcine model of implant-associated osteomyelitis. In total, 12 female pigs were allocated into 3 groups based on inoculum (n = 4 in each group). An implant cavity (IC) was drilled in the right tibia and followed by inoculation and insertion of a steel implant. All pigs were inoculated with 10 μL containing either: 11.79 mg synthetic Chlorosphaerolactylate B + 104 CFU of S. aureus (Group A), 104 CFU of S. aureus (Group B), or pure saline (Group C), respectively. Pigs were euthanized five days after inoculation. All Group B animals showed macroscopic and microscopic signs of bone infection and both tissue and implant harbored S. aureus bacteria (mean CFU on implants = 1.9 × 105). In contrast, S. aureus could not be isolated from animals inoculated with saline. In Group A, two animals had a low number of S. aureus (CFU = 6.7 × 101 and 3.8 × 101, respectively) on the implants, otherwise all Group A animals were similar to Group C animals. In conclusion, synthetic Chlorosphaerolactylate B holds potential to be a novel antimicrobial and antibiofilm compound.

Expert workshop summary: Advancing toward a standardized murine model to evaluate treatments for antimicrobial resistance lung infections.

The rise in antimicrobial resistance (AMR), and increase in treatment-refractory AMR infections, generates an urgent need to accelerate the discovery and development of novel anti-infectives. Preclinical animal models play a crucial role in assessing the efficacy of novel drugs, informing human dosing regimens and progressing drug candidates into the clinic. The Innovative Medicines Initiative-funded “Collaboration for prevention and treatment of MDR bacterial infections” (COMBINE) consortium is establishing a validated and globally harmonized preclinical model to increase reproducibility and more reliably translate results from animals to humans. Toward this goal, in April 2021, COMBINE organized the expert workshop “Advancing toward a standardized murine model to evaluate treatments for AMR lung infections”. This workshop explored the conduct and interpretation of mouse infection models, with presentations on PK/PD and efficacy studies of small molecule antibiotics, combination treatments (β-lactam/β-lactamase inhibitor), bacteriophage therapy, monoclonal antibodies and iron sequestering molecules, with a focus on the major Gram-negative AMR respiratory pathogens Pseudomonas aeruginosa, Klebsiella pneumoniae and Acinetobacter baumannii. Here we summarize the factors of variability that we identified in murine lung infection models used for antimicrobial efficacy testing, as well as the workshop presentations, panel discussions and the survey results for the harmonization of key experimental parameters. The resulting recommendations for standard design parameters are presented in this document and will provide the basis for the development of a harmonized and bench-marked efficacy studies in preclinical murine pneumonia model.

Ophthalmic suspension of Brimonidine for sustained delivery using nano-resin/drug complex technique

Brimonidine is used to lower intraocular pressure (IOP) in glaucoma patients. An ophthalmic Brimonidine formulation was developed to reduce the dosing frequency from three times a day to once a day using a drug/nanoresin complex suspension. Cationic Brimonidine forms complex with Amberlite™ IRP69 resin in an aqueous medium. The resin was milled to nanosize range and characterized for simulated mucous interaction and drug complexation. The drug/nanoresin complex was amorphous and showed ion-triggered release of Brimonidine in presence of tear salts. Nano-resin/drug ophthalmic suspension of 0.35% strength was formulated with excipients that did not interfere with drug/nanoresin complexation. The Brimonidine ophthalmic suspension had a pH value of 6.8–7.2, viscosity value ∼40–80cps, osmolality ∼280–350 mOsm/kg, D50 of 0.190 μm and complied with pharmacopoeial antimicrobial efficacy test. In-vitro release of Brimonidine from nano-resin complex formulation was slower in water than simulated tear fluid. The suspension was stable for 18 months at room temperature. In-vivo animal study showed comparable efficacy of once a day 0.35% nano-resin formulation to three times a day 0.15% solution formulation. There was improved absorption of the drug in aqueous humor which translated to a significantly high peak IOP reduction for a sustained period.

Evaluation of Antimicrobial Activity of Thymbra spicata L. var. spicata Essential Oil as a Potential Source of Herbal Medicine

Background: Since ancient times, human kind has used plants for their flavor and essence and especially for medical purposes; they are also used as food sources. Turkey, due to its geographical location, is home to many varieties of species of medicinal and aromatic plants. Aromatic and medicinal plants produce essential oils in the form of secondary metabolites. These essential oils are being used in the food, cosmetic, and pharmaceutical industries. Due to the various side effects of synthetic agents, the use of essential oils as antimicrobial agents comes to the fore. Objective: The purpose of this study was to determine the essential oil composition of Thymbra spicata L. var. spicata collected from the Gaziantep Region of Turkey and to evaluate its antimicrobial efficacy against microorganism species commonly encountered in food, cosmetic, and pharmaceutical industries. Methods: In this study, the antimicrobial effect of the volatile oil obtained from dried leaves of Thymbra spicata L. var. spicata, traditionally known as Zahter, was investigated. For this purpose, volatile oil was obtained from the leaves of the plant by steam vapor distillation method. Antimicrobial efficacy tests were conducted against microorganisms; Staphylococcus aureus, Enterococcus hirae, Enterococcus faecalis, Listeria monocytogenes, Escherichia coli, Klebsiella pneumoniae, Proteus hauseri, Pseudomonas aeruginosa, Salmonella typhimurium, and Candida albicans. Results: Results of the experiments showed that the volatile oil obtained from Thymbra spicata L. var. spicata had a cidal effect on selected pathogenic microorganisms even at low concentrations. Conclusion: This study showed that the high carvacrol content of the T. spicata L. var. spicata grown in the Gaziantep region of Turkey is a promising source of antimicrobial raw materials in the pharmaceutical, cosmetic, and food industries.

Modified Vaccinia Virus Ankara as a Potential Biosafety Level 2 Surrogate for African Swine Fever Virus in Disinfectant Efficacy Tests.

In South Korea, despite the increase in emerging viral pathogens in the veterinary industry, only efficacy-tested, virus-specific disinfectants are allowed to be used. Moreover, domestic testing of disinfectants for their virucidal efficacies against foreign, malignant, infectious pathogens that are unreported within the country and/or contagious livestock diseases that require special attention regarding public hygiene are legally restricted. Therefore, the Animal and Plant Quarantine Agency (APQA) designed a study to select a potential biosafety level 2 surrogate of African swine fever virus (ASFV) for efficacy testing to improve the disinfectant approval procedures. For this, the modified vaccinia virus Ankara (MVA) was compared to ASFV in terms of its susceptibility to disinfectants. Effective concentrations of active substances of disinfectants (potassium peroxymonosulfate, sodium dichloroisocyanurate, malic acid, citric acid, glutaraldehyde, and benzalkonium chloride) against ASFV and MVA were compared; similarly, efficacies of APQA-listed commercial disinfectants were examined. Tests were performed according to APQA guidelines, and infectivities of ASFV and MVA were confirmed by hemadsorption and cytopathic effect, respectively. The results reveal that the disinfectants are effective against MVA at similar or higher concentrations than those against ASFV, validating the use of MVA as a potential biosafety level 2 surrogate for ASFV in efficacy testing of veterinary disinfectants.

Interlaboratory study for the evaluation of three microtiter plate-based biofilm quantification methods

Microtiter plate methods are commonly used for biofilm assessment. However, results obtained with these methods have often been difficult to reproduce. Hence, it is important to obtain a better understanding of the repeatability and reproducibility of these methods. An interlaboratory study was performed in five different laboratories to evaluate the reproducibility and responsiveness of three methods to quantify Staphylococcus aureus biofilm formation in 96-well microtiter plates: crystal violet, resazurin, and plate counts. An inter-lab protocol was developed for the study. The protocol was separated into three steps: biofilm growth, biofilm challenge, biofilm assessment. For control experiments participants performed the growth and assessment steps only. For treatment experiments, all three steps were performed and the efficacy of sodium hypochlorite (NaOCl) in killing S. aureus biofilms was evaluated. In control experiments, on the log10-scale, the reproducibility SD (SR) was 0.44 for crystal violet, 0.53 for resazurin, and 0.92 for the plate counts. In the treatment experiments, plate counts had the best responsiveness to different levels of efficacy and also the best reproducibility with respect to responsiveness (Slope/SR = 1.02), making it the more reliable method to use in an antimicrobial efficacy test. This study showed that the microtiter plate is a versatile and easy-to-use biofilm reactor, which exhibits good repeatability and reproducibility for different types of assessment methods, as long as a suitable experimental design and statistical analysis is applied.

A global disinfectant standard for cleanrooms: Presenting a harmonised approach

Disinfectant efficacy testing is an essential part of a facility contamination control strategy. Pharmaceutical and healthcare products facilities must know that the products they are using can achieve effective levels of microbial kill across a range of surface types. The problem faced by microbiologists and production managers is that the various national and international standards use different methodologies. In addition, these standards and methods have not been written specifically for cleanrooms and the microbial test panels and logarithmic reduction expectations are not considered suitable. In order to develop an international standard suitable for all pharmaceutical facility cleanrooms, Ecolab has developed the Validex™ method, which is independently assessed in this paper. This method involves using 2 cm diameter disks, to target a 3 log reduction for vegetative bacteria in 5 minutes; and a 2 log reduction for fungi and bacterial spores in 10 minutes. The key criteria and rationale for selection, along with the methodology, are presented in this paper.