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OBJECTIVE: The aim of this in vitro experimental series was to explore the mode of action of a hydrocellular polyurethane foam dressing (HPFD) and how its advanced features support beneficial interactions with the wound bed to address common barriers to wound healing, thus supporting improved clinical outcomes. METHOD: Multiple in vitro microbiological tests were performed, assessing prevention of bacterial ingress, surface removal of bacteria, bacterial sequestration and retention into the dressing in a clinically relevant environment. Odour molecule concentrations were measured using gas chromatography and further assays explored matrix metalloproteinase (MMP)-9 retention in the dressing using enzyme linked immunosorbent assay. RESULTS: The HPFD demonstrated marked reductions in bioburden levels across multiple tests. These included prevention of bacterial ingress for seven days, removal of surface bacteria and absorption into the dressing. Further tests identified that most bacteria were sequestered into the hyperabsorbent layer (90.5% for Pseudomonas aeruginosa and 89.6% for meticillin-resistant Staphylococcus aureus). Moreover, the majority of bacteria (99.99% for both test organisms) were retained within the dressing, even upon compression. Additional tests demonstrated a marked reduction of odour molecules following incubation with HPFD and total retention of protease MMP-9 within the dressing. CONCLUSIONS: Proactive management of the wound environment with an appropriate advanced wound dressing, such as the HPFD examined in these in vitro investigations, can not only help to minimise the barriers to healing, as observed across this test series by direct interaction with the wound bed, but may, as a result, provide an ideal environment for wound progression with minimal disturbance.

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Cleanrooms are controlled environments where the number of airborne particles is reduced to a level defined by an International Organization for Standardization (ISO) standard. These facilities have applications in different fields, such as the electronic, pharmaceutical, and healthcare sectors, and are also necessary for the assembly, testing and handling of space hardware. Cleanrooms are expensive to build and maintain and require the permanent designation of infrastructures and dedicated spaces within a building. Once built, clean rooms cannot be used for any other purpose, as contamination is a significant risk. The restricted access to these facilities limits the process of designing, testing, and calibrating instruments developed by academic institutions, small companies, and space startups. Here we present a Commercial Off-The-Shelf (COTS) procedure for building and maintaining a highly controlled ISO class 5 cleanroom, according to ISO14644 standards. We provide a detailed explanation of how to design, develop and operate a portable, modular, and cost-effective ISO class 5 cleanroom that can be used for the usual workflow of development, integration, test procedures and planetary protection associated with the design of instrumentation for planetary exploration.

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Historically, fuel microbiology studies have relied on culture data. Potentially relevant but unculturable bacteria were not detected. Although ATP can quantify total microbial bioburdens in fuels, it cannot differentiate among the taxa present. Quantitative PCR (qPCR) testing promises to fill this gap by quantifying targeted amplicon sequences thereby detecting both culturable and non-culturable taxa and quantifying specifically targeted taxa. In this study, fluid samples drawn from the fuel, interface and water phases of fuel over water microcosms were tested for cellular ATP concentration ([cATP]) and qPCR bioburdens. Additionally, surface swab samples from steel corrosion coupon surfaces exposed to each of these three phases were collected and tested for total ATP concentration ([tATP]) and qPCR bioburdens. Statistical relationships between ATP and qPCR bioburdens were examined. Correlation coefficients between the two variables were matrix dependent and ranged from negligible (|r|=0.2) to strong (|r|=0.7). When results were categorized into negligible, moderate and heavy bioburdens, parameter agreement was again matrix dependent. Percentage agreement between [ATP] and qPCR gene copies ranged from 11 % to 89 % - with qPCR-bioburden ratings typically being greater than ATP-bioburden ratings.

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Negative Pressure Wound Therapy (NPWT) has been widely adopted in wound healing strategies due to its multimodal mechanism of action. While NPWT's positive impression on wound healing is well-established, its effect on bacterial load reduction remains equivocal. This study investigates NPWT's efficacy in reducing bioburden using an in vitro porcine skin model, focusing on the impact of Staphylococcus aureus and Staphylococcus epidermidis. Custom-made negative pressure chambers were employed to apply varying negative pressures. Porcine skin was cut into 5 × 5 cm squares and three standardized wounds of 6 mm each were created using a biopsy punch. Then, wounds were infected with S. aureus and S. epidermidis bacterial suspensions diluted 1:10,000 to obtain a final concentration of 1.5 × 104 CFU/ml and were placed in negative pressure chambers. After incubation, bacterial counts were expressed as colony-forming units (CFU) per ml. For S. aureus at 120 hours, the median CFU, mean area per colony, and total growth area were notably lower at -80 mmHg when compared to -250 mmHg and -50 mmHg, suggesting an optimal negative pressure for the pressure-dependent inhibition of the bacterial proliferation. While analyzing S. epidermidis at 120 hours, the response to the negative pressure was similar but less clear, with the minor CFU at -100 mmHg. The influence of intermittent negative pressure on the S. epidermidis growth showed notably lower median CFU with the interval therapy every hour compared to the S. aureus control group. This study contributes valuable insights into NPWT's influence on the bacterial load, emphasizing the need for further research to reformulate its role in managing contaminated wounds.

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BACKGROUND: The Mettler-Toledo 7000RMS analyzer is a Bio-Fluorescent Particle Counter (BFPC) used to monitor real-time bioburden results from Purified Water (PW). OBJECTIVE: Validation of the analyzer using 13 microorganisms and a low-intensity, fluorescent, polystyrene bead. METHODS: During the execution of the validation, a laboratory water system that met Purified Water (PW) quality standards was connected to the 7000RMS, and a syringe pump was used to introduce various concentrations of microorganisms and fluorescent polystyrene beads to the analyzer. Samples were collected and tested via the traditional Membrane Filtration (MF) method and the Colony Forming Unit (CFU) plate count results were compared to the Auto-Fluorescent Unit (AFU) of the 7000RMS analyzer. The validation study was designed to follow the guidance in United States Pharmacopeia (USP) Chapter <1223 > (1), European Pharmacopeia (EP) Chapter 5.1.6 (2), PDA Technical Report 33 (3). Concepts and strategies were adapted from EP Chapter 2.6.12 Microbiological Examination of Non-sterile Products: Microbial Enumeration Tests, EP 10.2 (4), European Pharmacopeia Chapter 2.6.1 Sterility, EP 10.2 (5), USP Chapter <61> Microbiological Examination of Non-sterile Products: Microbial Enumeration Tests (6), USP Chapter <71> Sterility Tests (7), Japanese Pharmacopoeia (JP) General Information Chapter G8 Water: Quality Control of Water for Pharmaceutical Use (8). RESULTS AND CONCLUSION: All pre-determined validation acceptance criteria for Accuracy, Specificity, Precision, Limit of Detection (LOD), Limit of Quantitation (LOQ), Linearity, and Range were met. Further, the 7000RMS demonstrated Performance Equivalence to the MF method per USP <1223> but characteristically lacked correlation to the CFU. HIGHLIGHTS: This validation approach highlights the superior capabilities of the 7000RMS when compared against the traditional compendial MF testing method for PW.

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In the execution of its legislated responsibilities, the United States Food and Drug Administration commonly refers to standard test methods detailed in the United States Pharmacopeia (USP). Microbiological test methods (contained in general chapters) are listed in chapters <51> to <80> with details regarded as enforceable where referenced as a test method. USP <61> "Microbiological Examination of Nonsterile Products: Microbial Enumeration Tests" is a globally harmonized chapter that has been successfully employed for the enumeration of microorganisms recoverable from nonsterile finished drug products. The content of USP <61> is not always scientifically principled nor emphatically understood by all pharmaceutical microbiologists. Consequently, misunderstanding and misapplication of USP <61> may result in analyses and assessments of microbiological quality that are flawed or erroneous. In this article, clarification is provided to assist the pharmaceutical microbiologist in the appropriate and intended use of USP <61>, including provision of details not always commonly known or understood.

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Microbiological contamination may cause microbial proliferation and consequently additional problems for pharmaceutical companies through production stoppage, product contamination, investigations of process deviations, out-of-specification results and product disposal. This is one of the major concerns of the regulatory health agencies. Microbiological load (bioburden) may represent a potential risk for patients if the sterilization process is not effective and/or due to the production of toxins. Although bioburden can be eliminated by terminal sterilization or filtration processes, it is important to monitor the amount and determine the identity and characteristics of the microorganisms present prior to final processing. The application of microorganism identification systems is crucial for identifying the type of contamination, which can be extremely useful for investigating. The aim of this study was to evaluate the profiles of microorganisms identified in bioburden assays from solutions, culture medias, and products (SCP) from a pharmaceutical industry facility. From 2018-2020, a total of 1,078 samples from 857 different lots of SCP were analyzed and isolated microorganisms were identified. A prefiltering step was included after March 2020, in order to reduce the bioburden before sterilizing filtration. Criteria for the definition and management of microorganisms identified were evaluated after an integrative bibliographic review, and three groups were proposed (critical, objectionable, and nonobjectionable microorganisms). For the samples that did not include prefiltering (n=636), 227 (35.7%) presented microbial growth. For those that included prefiltering, before prefiltering (n=221), 60.6% presented microbial growth, and after prefiltering, this value was reduced to 4.1%, which can be attributed to a contamination during the sampling or a wrong filtering. From the samples that presented microbial growth, 678 microorganisms were identified as bacteria and 59 as molds and yeasts. A total of 120 microorganisms (56 and 27 Gram-positive and negative bacteria, respectively, 31 yeasts, and six filamentous molds) could not be identified, and the remaining microorganisms were classified as objectionable (n=507; 82.2%), nonobjectionable (n=103; 16.7%) and critical (n=7; 1.1%). Most of the bioburden species (>80.0%) were considered objectionable microorganisms. A process for classification and management of bioburden analysis results based on a literature review of pathogenic and physiological characteristics of the microorganisms was proposed.

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The suspension wet media milling manufacturing process is a complex multi-unit operation, resulting in drug substance comminution to a target particle size. As a result of this complexity, microbial contamination is of paramount concern, particularly for suspensions dosed for parenteral use. This perspective sought to review the influence of (4) critical manufacturing unit operations using a quality risk management approach to better identify and articulate impact of each unit operation on bioburden viability. The manufacturing unit operations in scope included slurry compounding, deaeration, milling, and filling. Bow tie risk analysis was used as a visual gap analysis tool to evaluate if conventional controls were appropriate to detect and mitigate potential for microbial contamination. A deep dive into these unit operations clarified that mechanisms such as turbohypobiosis, cavitation during deaeration, high energy milling, and inert overlay may have an appreciable influence on bioburden viability and proliferation. The resultant analysis also explicated that endotoxin oversight must be closely monitored through barriers (input material controls, water quality controls) to minimize impact to the product and patient. The identified manufacturing unit operations were not appropriate as mitigating controls for endotoxin. The output of this article relates risk intersections for microbial contamination during wet media milling and offers insights in critical areas for intervention.

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Bioburden detection is crucial for food, water, and biopharmaceutical applications as it can directly impact public health. The objective of this study is to develop and validate an assay and protocol for detecting bioburden on solid surfaces, as well as in water, with high sensitivity and accuracy in a rapid manner. Henceforth, a resazurin-based assay optimized for detecting bioburden has been integrated with a previously developed portable multichannel fluorometer. The microbes were isolated from solid surfaces in different laboratory settings by swabbing technique, and stream water was collected for contamination analysis. Based on the results, the assay and protocol can successfully detect bioburden as low as 20 CFU/cm2 and 10 CFU/mL present in both surface and water samples, respectively.

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The move to integrated continuous bioprocessing (ICB), while providing a means for process intensification, can put added strain on process analytics when conventional methods are used. For instance, traditional microbial methods provide minimal value to ICB processes given that the time required for data to become available is much longer than a typical full cycle of the manufacturing process. Although rapid microbial detection has been in discussion for over 30 years, it is still not routinely deployed in commercial biopharmaceutical manufacturing. One contributing factor is the ability to integrate this technology into a process control strategy and existing quality systems. An understanding of the capability of microbial detection technology available today can be leveraged to implement a control strategy for bioburden monitoring in real time for process intermediates. One key tenet of this proposed control strategy is the use of a "two-tiered approach" wherein a fast (but possibly less sensitive) test is used to monitor the process and trigger further action for a second, longer duration test which is used to confirm and quantify the presence of bioburden and identify the organism. This approach, presented here alongside several case studies for microbial monitoring, can have broader application for other process analytical technologies where fit for purpose methods could be employed to establish process control alongside real time continuous processes.

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BACKGROUND: The dramatic increase of drug-resistant bacteria necessitates urgent development of platforms to simultaneously detect and inactivate bacteria causing wound infections, but are confronted with various challenges. Delta amino levulinic acid (ALA) induced protoporphyrin IX (PpIX) can be a promising modality for simultaneous bioburden diagnostics and therapeutics. Herein, we report utility of ALA induced protoporphyrin (PpIX) based simultaneous bioburden detection, photoinactivation and therapeutic outcome assessment in methicillin resistant Staphylococcus aureus (MRSA) infected wounds of mice. METHODS: MRSA infected wounds treated with 10% ALA were imaged with help of a blue LED (∼405 nm) based, USB powered, hand held device integrated with a modular graphic user interface (GUI). Effect of ALA application time, bacteria load, post bacteria application time points on wound fluorescence studied. PpIX fluorescence observed after excitation with blue LEDs was used to detect bioburden, start red light mediated antimicrobial photodynamic therapy (aPDT), determine aPDT effectiveness and assess selectivity of the approach. RESULTS: ALA-PpIX fluorescence of wound bed discriminates infected from uninfected wounds and detects clinically relevant load. While wound fluorescence pattern changes as a function of ALA incubation and post infection time, intra-wound inhomogeneity in fluorescence correlates with the Gram staining data on presence of biofilms foci. Lack of red fluorescence from wound granulation tissue treated with ALA suggests selectivity of the approach. Further, significant reduction (∼50%) in red fluorescence, quantified using the GUI, relates well with bacteria load reduction observed post topical aPDT. CONCLUSION: The potential of ALA induced PpIX for simultaneous detection of bioburden, photodynamic inactivation and "florescence-guided aPDT assessment" is demonstrated in MRSA infected wounds of mice.

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There is an increasing use of non-medicated wound dressing with claims of irreversible bacterial binding. Most of the data are from in vitro models which lack clinical relevance. This study employed a range of in vitro experiments to address this gap and we complemented our experimental designs with in vivo observations using dressings obtained from patients with diabetes-related foot ulcers. A hydrophobic wound dressing was compared with a control silicone dressing in vitro. Test dressings were placed on top of a Pseudomonas aeruginosa challenge suspension with increasing concentrations of suspension inoculum in addition to supplementation with phosphate buffered saline (PBS) or increased protein content (IPC). Next, we used the challenge suspensions obtained at the end of the first experiment, where bacterial loads from the suspensions were enumerated following test dressing exposure. Further, the time-dependent bacterial attachment was investigated over 1 and 24 h. Lastly, test dressings were exposed to a challenge suspension with IPC, with or without the addition of the bacteriostatic agent Deferiprone to assess the impacts of limiting bacterial growth in the experimental design. Lastly, two different wound dressings with claims of bacterial binding were obtained from patients with chronic diabetes-related foot ulcers after 72 h of application and observed using scanning electron microscope (SEM). Bacteria were enumerated from each dressing after a 1-h exposure time. There was no statistical difference in bacterial attachment between both test dressings when using different suspension inoculum concentrations or test mediums. Bacterial attachment to the two test dressings was significantly lower (p < 0.0001) when IPC was used instead of PBS. In the challenge suspension with PBS, only the hydrophobic dressing achieved a statistically significant reduction in bacterial loads (0.5 ± 0.05 log colony forming units; p = 0.001). In the presence of IPC, there was no significant reduction in bacterial loads for either test dressing. When bacterial growth was arrested, attachment to the test dressings did not increase over time, suggesting that the number of bacteria on the test dressings increases over time due to bacterial growth. SEM identified widespread adsorption of host fouling across the test dressings which occurred prior to microbial binding. Therein, microbial attachment occurred predominantly to host fouling and not directly to the dressings. Bacterial binding is not unique to dialkylcarbamoyl chloride (DACC) dressings and under clinically relevant in vitro conditions and in vivo observations, we demonstrate (in addition to previously published work) that the bacterial binding capabilities are not effective at reducing the number of bacteria in laboratory models or human wounds.

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A commercial bacterial cellulose-monolaurin wound dressing was investigated for changes in the chemical structure, mechanical strength, thermal degradation, morphology, and functional swelling properties after exposure to gamma and electron beam radiations at doses 15-50 kGy. Radiation-induced oxidation occurred as seen in the FT-IR peaks at 1720-1750 cm-1. Degradation of the cellulosic network was observed in tensile strength reduction and shift in degradation temperature to lower values. The SEM cross-section images of the irradiated dressings revealed a less dense nanostructure network compared to the non-irradiated samples while the XRD diffractograms indicated a change in lattice direction/plane. Despite these changes, irradiation caused no significant effect on the functional properties especially at 15-25 kGy doses where most biomedical devices are sterilized. All irradiated wound dressings exhibited physical integrity, increased exudate absorption, and water vapor transmission rate - properties beneficial to wound-healing functionality. The pre-selected sterilization dose of 15 kGy for each ionizing radiation was successfully verified and substantiated following ISO 11137-2:2016, hence ionizing radiation is a suitable sterilization modality for the product.

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Holistic concepts should be applied that reduce risks prior to final bioburden testing and sterile filtration, based on enhanced process and product attribute understanding, which could be key to successful bioburden risk management. Key findings of this paper include.

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Planetary protection is a guiding principle aiming to prevent microbial contamination of the solar system by spacecraft (forward contamination) and extraterrestrial contamination of the Earth (backward contamination). Bioburden reduction on spacecraft, including cruise and landing systems, is required to prevent microbial contamination from Earth during space exploration missions. Several sterilization methods are available; however, selecting appropriate methods is essential to eliminate a broad spectrum of microorganisms without damaging spacecraft components during manufacturing and assembly. Here, we compared the effects of different bioburden reduction techniques, including dry heat, UV light, isopropyl alcohol (IPA), hydrogen peroxide (H2O2), vaporized hydrogen peroxide (VHP), and oxygen and argon plasma on microorganisms with different resistance capacities. These microorganisms included Bacillus atrophaeus spores and Aspergillus niger spores, Deinococcus radiodurans, and Brevundimonas diminuta, all important microorganisms for considering planetary protection. Bacillus atrophaeus spores showed the highest resistance to dry heat but could be reliably sterilized (i.e., under detection limit) through extended time or increased temperature. Aspergillus niger spores and D. radiodurans were highly resistant to UV light. Seventy percent of IPA and 7.5% of H2O2 treatments effectively sterilized D. radiodurans and B. diminuta but showed no immediate bactericidal effect against B. atrophaeus spores. IPA immediately sterilized A. niger spores, but H2O2 did not. During VHP treatment under reduced pressure, viable B. atrophaeus spores and A. niger spores were quickly reduced by approximately two log orders. Oxygen plasma sterilized D. radiodurans but did not eliminate B. atrophaeus spores. In contrast, argon plasma sterilized B. atrophaeus but not D. radiodurans. Therefore, dry heat could be used for heat-resistant component bioburden reduction, and VHP or plasma for non-heat-resistant components in bulk bioburden reduction. Furthermore, IPA, H2O2, or UV could be used for additional surface bioburden reduction during assembly and testing. The systemic comparison of sterilization efficiencies under identical experimental conditions in this study provides basic criteria for determining which sterilization techniques should be selected during bioburden reduction for forward planetary protection.

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IMPORTANCE: Planetary protection at the National Aeronautics and Space Administration (NASA) requires bioburden on certain spacecraft to be estimated via sampling in order to comply with biological cleanliness requirements. To achieve this, the recovery efficiency of devices used to sample the spacecraft pre-launch must be understood and their uncertainty quantified in order to produce the most reasonable estimates of bioburden. This study brings together experiments performed by NASA and the European Space Agency with approved swab and wipe sampling devices, inoculating steel coupons with laboratory strains of Bacillus spp. spores commonly recovered from spacecraft assembly clean rooms (B. atrophaeus, B. megaterium, B. safensis and B. thuringiensis), with a mathematical model of the assay process to assess recovery efficiency. The statistical treatment developed in this study allows comparison of bioburden estimates made from different devices processed by different methods. This study also gives stakeholders and practitioners a statistically rigorous approach to predict bioburden that can be folded into future modeling efforts.

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Bedside dialysis monitoring equipment for hemodialysis are located in the bioburden section upstream of the endotoxin-retentive filter for dialysis fluid sterilization. We observed 26 equipment at our institution for bacterial contamination at least once every 4 weeks for 5 years with another ultrafiltration membrane upstream to prevent bacterial contamination. Bacterial contamination levels were highest and most diverse at the time of the first flush. During subsequent initial cleanng, the contamination level decreased, and bacterial species converged almost exclusively to one genus, namely Methylobacterium spp. During clinical use, the equipment were cleaned and disinfected daily after dialysis, and daily operations and maintenance were performed using aseptic techniques. Although the frequency of bacterial detection decreased annually, the same bacterial genotypes observed at the first flush were isolated even after long time periods and were thought to persist in the equipment possibly by forming biofilm. Pseudomonas aeruginosa was newly detected after the replacement of parts during breakdown maintenance, indicating the need to sterilize replacement parts. Thus, the bioburden should be assessed regularly as part of the management of in-house-produced dialysis fluid.

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Wound healing is a complex system including such key players as host, microbe, and treatments. However, little is known about their dynamic interactions. Here we explored the interplay between: (1) bacterial bioburden and host immune responses, (2) bacterial bioburden and wound size, and (3) treatments and wound size, using murine models and various treatment modalities: Phosphate buffer saline (PBS or vehicle, negative control), doxycycline, and two doses of A. baumannii phage mixtures. We uncovered that the interplay between bacterial bioburden and host immune system may be bidirectional, and that there is an interaction between host CD3+ T-cells and phage dosage, which significantly impacts bacterial bioburden. Furthermore, the bacterial bioburden and wound size association is significantly modulated by the host CD3+ T-cells. When the host CD3+ T-cells (x on log10 scale) are in the appropriate range (1.35 < x < = 1.5), we observed a strong association between colony forming units (CFU) and wound size, indicating a hallmark of wound healing. On the basis of the findings and our previous work, we proposed an integrated parallel systems biology model.

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Treating wound infections is a challenging concern in various clinical settings in Egypt, especially in the increasing global problem of resistance to antimicrobials. Here, we aimed to fabricate CuO NPs via green synthesis using aqueous Yucca gigantea extract. Then, the effect of green synthesized CuO NPs on Staphylococcus aureus clinical isolates has been studied in vivo and in vitro. The aqueous extract of Yucca gigantea has been employed in our study as a scale-up approach to safely, affordably, sustainably, and practically fabricate copper oxide nanoparticles (CuO NPs). Fourier transforms infrared (FT-IR), X-ray Diffraction (XRD), and UV-vis spectroscopy were utilized in vitro to describe the bonding features of CuO NPs.Scanning Electron microscopy (SEM), Transmission electron microscopy (TEM), Energy dispersive X-ray (EDX), and dynamic light scattering (DLS) were used to detect the morphological and elemental composition of the resulting CuO NPs. The fabrication of CuO NPs was confirmed by the IR spectral band at 515 cm-1, ensuring the metal-oxygen bondCu-O with two strong bands at 229 and 305 nm. SEM and TEM show CuO NPs with a size range from 30 to 50 nm. Cu and O comprised most of the particles produced through green synthesis, with weight percentages of 57.82 and 42.18 %, respectively. CuO NPs were observed to have a Zeta-potential value of -15.7 mV, demonstrating their great stability. CuO NPs revealed antibacterial potential toward the tested isolates with minimum inhibitory concentration values of 128 to 512 µg/mL. CuO NPs had antibiofilm potential by crystal violet assay, downregulating the expression of icaA and icaD genes in 23.07 % and 19.32 of the S. aureus isolates. The wound-healing potential of CuO NPs was investigated in vivo. It significantly decreased the bacterial burden and increased wound healing percentage compared to the positive control group. Moreover, CuO NPs caused an upregulation of the genes encoding platelet-derived growth factor (PDGF) and fibronectin in tissue repair. Thus, we can use CuO NPs as a future source for wound healing materials, especially in infected wounds.

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The Mars 2020 Perseverance rover is equipped with a Sample Caching System (SCS) designed to collect and cache martian core and regolith samples for potential return to Earth. To ensure the integrity of these samples, the mission requirements for each encapsulated sample for return is less than one Earth-sourced viable organism (VO) and more than a 99.9% probability of being free of any Earth-sourced VO. To satisfy the stringent biological contamination requirements in support of return sample science investigations, special bioburden mitigation and reduction approaches were developed and implemented for SCS hardware that would directly contact or be in close proximity to the martian samples. In this study, we describe the implemented approaches for microbiological contamination reduction and mitigation, detail the processes of the SCS aseptic assembly, and report the estimated VO for each returned sample. We found that our conservative estimate of the computed probability of a single VO in the returned sample is more than one order of magnitude lower than the biological contamination requirement while the best estimate exceeds two orders of magnitude.

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