Use of 70% alcohol for the routine removal of microbial hard surface bioburden in life science cleanrooms

Synthetic Microbial Surrogates Consisting of Lipid Nanoparticles Encapsulating DNA for the Validation of Surface Disinfection Procedures

Effective cleaning and disinfection procedures are an integral part of good manufacturing practice and in maintaining hygiene standards in health-care facilities. In this study, a method to validate such cleaning and disinfection procedures of surfaces was established employing lipid nanoparticles (LNPs) encapsulating DNA. It was possible to determine and distinguish between the physical cleaning effect (dilution) and the chemical cleaning effect (disintegration) on the LNPs during the cleaning and disinfection procedure (wiping). After treatment with 70 v % ethanol as a disinfectant and SDS solution as a cleaning agent, LNPs showed log₁₀ reductions of 4.5 and 4.0, respectively. These values are similar to the log₁₀ reductions exhibited by common bacteria, such as Escherichia coli and Serratia marcescens. Therefore, LNPs pose as useful tools for cleaning validation with advantages over the already existing tools and enable a separate detection of dilution and chemical disinfectant action.

Electrospun Poly(lactic acid) and Silk Fibroin Based Nanofibrous Scaffold for Meniscus Tissue Engineering

Biopolymer based scaffolds are commonly considered as suitable materials for medical application. Poly(lactic acid) (PLA) is one of the most popular polymers that has been used as a bioscaffold, but it has poor cell adhesion and slowly degrades in an in vitro environment. In this study, silk fibroin (SF) was selected to improve cell adhesion and degradability of electrospun PLA. In order to fabricate a PLA/SF scaffold that offered both biological and mechanical properties, related parameters such as solution viscosity and SF content were studied. By varying the concentration and molecular weight of PLA, the solution viscosity significantly changed. The effect of solution viscosity on the fiber forming ability and fiber morphology was elucidated. In addition, commercial (l-lactide, d-lactide PLA) and medical grade PLA (pure PLLA) were both investigated. Mechanical properties, thermal properties, biodegradability, wettability, cell viability, and gene expression of electrospun PLA and PLA/SF based nanofibrous scaffolds were examined. The results demonstrated that medical grade PLA electrospun scaffolds offered superior mechanical property, degradability, and cellular induction for meniscus tissue regeneration. However, for commercial non-medical grade PLA used in this study, it was not recommended to be used for medical application because of its toxicity. With the addition of SF in PLA based scaffolds, the in vitro degradability and hydrophilicity were improved. PLAmed50:SF50 scaffold has the potential to be used as biomimetic meniscus scaffold for scaffold augmented suture based on mechanical properties, cell viability, gene expression, surface wettability, and in vitro degradation.

Assessment of occupational exposure to nebulized isopropyl alcohol as disinfectant during aseptic compounding of parenteral cytotoxic drugs in cleanrooms

Pharmacy technicians are exposed to volatile organic compounds, like the disinfectant isopropyl alcohol (IPA), during the process of aseptic compounding of parenteral cytotoxic drugs. The occupational exposure to nebulized IPA during aseptic compounding has not been investigated. The aim of this study was to investigate the exposure to IPA during aseptic compounding of parenteral cytotoxic drugs and to assess compliance with legal and regulatory limits. As a secondary endpoint, the difference between two disinfection methods was compared regarding the exposure to IPA. The exposure to IPA was measured during five working shifts of 8 hr and one shift of 4 hr. The concentration IPA was measured by using a six-gas monitor. Total daily exposure was calculated as 8-hr Time Weighted Average (TWA) air concentration in mg/m³ and compared with an Occupational Exposure Limit (OEL) value of 500 mg/m³ and incidental peak exposure of 5,000 mg/m³. To assess whether the 8-hr TWA air concentration meets the legal and regulatory limits the Similar Exposure Groups (SEG) compliance test was used. A paired sample t-test was conducted to assess difference in exposure between two disinfection methods. The average 8-hr TWA exposure to IPA during the six measurements varied from 2.6 mg/m³ to 43.9 mg/m³ and the highest momentary concentration measured was 860 mg/m³. The result of the SEG compliance test was 3.392 (U_r value) and was greater than the U_t value of 2.187 which means the exposure to IPA is in compliance with the OEL value. No significant difference in exposure was shown between two disinfection methods (p = 0.49). In conclusion, exposure to IPA during aseptic compounding of parenteral cytotoxic drugs showed compliance to the OEL values with no significant difference in exposure between two disinfection methods.

Disinfection protocol for human musculoskeletal allografts in tissue banking using hydrogen peroxide 30

Musculoskeletal allografts are used in reconstructive procedures, however, the risk of contamination with potential pathogens is possible, and safe transplantation requires multiple processing considerations. Hydrogen peroxide (H₂O₂) has commonly been used in bone washing because it can remove donor cells and eliminate antigens, pathogens, or cytotoxic agents from the matrix. The aim of this study was to evaluate the quantitative activity of H₂O₂ in a model of bone contamination with a high bacterial load to define the bioburden reduction. Twelve bone disc models were artificially contaminated with Staphylococcus aureus. The bones were treated with a washing process composed by antibiotics, 30% hydrogen peroxide, and 70% alcohol. Tryptic Soy Agar plates were directly inoculated with 100µL of each step of the washing process and colonies were counted in CFU/mL. Scanning electron microscopy was used for bone structural analysis before and after the washing process. After antibiotics, there was a drop of less than 1 log for cancellous bone and almost 1 log for cortical bone. However, after H₂O₂, there as a drop of 3 logs for cortical (p = 0.007), and 2 logs for cancellous bone (p = 0.063). The use of alcohol did not change the bioburden following H₂O₂ in cancellous and cortical bone. Despite the important drop of bacterial load, H₂O₂ was not enough to completely eradicate bacterial with this model of bioburden. H₂O₂ is useful in decontamination, but antibiotics have little activity, and alcohol is useless. The process is useful in decontamination up to 3 logs of bioburden.

Back to Basics: Choosing the Appropriate Surface Disinfectant

From viruses to bacteria, our lives are filled with exposure to germs. In built environments, exposure to infectious microorganisms and their byproducts is clearly linked to human health. In the last year, public health emergency surrounding the COVID-19 pandemic stressed the importance of having good biosafety measures and practices. To prevent infection from spreading and to maintain the barrier, disinfection and hygiene habits are crucial, especially when the microorganism can persist and survive on surfaces. Contaminated surfaces are called fomites and on them, microorganisms can survive even for months. As a consequence, fomites serve as a second reservoir and transfer pathogens between hosts. The knowledge of microorganisms, type of surface, and antimicrobial agent is fundamental to develop the best approach to sanitize fomites and to obtain good disinfection levels. Hence, this review has the purpose to briefly describe the organisms, the kind of risk associated with them, and the main classes of antimicrobials for surfaces, to help choose the right approach to prevent exposure to pathogens.

Microwave Properties of Coplanar Waveguide-Based PEDOT:PSS Conducting Polymer Line in Ethanol Gas Atmosphere

This study aims to investigate the microwave properties of coplanar waveguide (CPW)-based poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) conducting polymer line in an ethanol gas atmosphere, with the frequency range of 0.5–2 GHz. For an ethanol-exposed PEDOT:PSS line (test sample), the transmission coefficient (S₂₁) decreased immediately; moreover, the microwave effective conductivity (σ_m/w) decreased simultaneously, compared with the ethanol-free PEDOT:PSS line (reference sample). The immediate variations in ΔS₂₁ ( = S_21,ethanol − S_21,free) and Δσ_m/w ( = σ_m/w,ethanol − σ_m/w,free) were approximately 10.2 dB and 2.7 × 10⁴ S/m, respectively. Furthermore, in the analysis of the circuit model of the PEDOT:PSS line, the characteristic impedance and distributed elements, i.e., resistance (R) and inductance (L) per length, of the test sample increased, compared with the reference sample. However, upon stopping the exposure to ethanol gas, the microwave properties of the test sample instantaneously recovered to those of the reference sample. According to these critical observations, we could confirm that the coplanar waveguide with a PEDOT:PSS line shows a significant difference in the diverse microwave properties, through rapid response to the ethanol gas at room temperature.