RAPID DETECTION AND ENUMERATION OF CONTAMINANTS BY ATP BIOLUMINESCENCE USING THE MILLIFLEX®RAPID MICROBIOLOGY DETECTION AND ENUMERATION SYSTEM

A rapid and simple sterility test method based on solid culture medium containing blood

Current sterility test performed for most biological products takes 14 days. We evaluated solid medium, containing 5% blood for use in the membrane filtration (MF) and direct inoculation (DI) sterility test. Representative microorganisms prepared in a sample matrix at approximately 0.1, 1, 10 and 100 colony forming units were tested for growth by compendial MF sterility test using fluid thioglycolate medium and tryptic soy broth and also on the Schaedler blood agar (SBA). Sterility test performed on SBA was significantly more sensitive and faster in detecting various microorganisms than the compendial method, particularly for sample matrix containing 0.01% thimerosal (p < 0.05). SBA detected all microorganisms within 7 days. To implement solid medium in the DI sterility test, multiple BA plates were inoculated with the sample. All representative microorganisms were detected within 5 days. The sterility test using solid medium required 3 different incubation conditions, 30-35 °C aerobically and anaerobically to detect bacteria, and at 20-25 °C aerobically to detect mold and yeast. To eliminate aerobic incubation of solid medium at 20-25 °C, we evaluated representative species of mold and yeast for their growth at 30-35 °C and 20-25 °C in the sterility test performed on solid medium. Penicillium chrysogenum could not be detected at 30-35 °C consistently within 7 days. Sterility test performed on solid medium without any additional technology could be completed in 7 days, as compared to the 14 days required for the current compendial method.

Towards an automated approach for smart sterility test examination

As new technologies emerge, deep learning applications are often integral parts of new products as features and often as differentiating benefits. This is especially notable in commercial consumer products in everyday applications, such as voice assistants or streaming content recommendation systems. Due to the power and applicability of these deep learning technologies significant efforts are being directed to the development and integration of appropriate models into science and engineering applications to supplant analogue systems that may be highly prone to human error. Here we present an innovative, low-cost approach to advance sterility assessment workflows that are required and regulated within drug release/manufacturing processes. The model system leverages off-the-shelf hardware as well as deep learning models to detect and classify different microbial contaminations in test containers. The paired hardware and software tools were evaluated in experiments using common model organisms (C. sporogenes, P. aeruginosa, S. aureus). With this approach we were able to detect all three test organisms across 40 experiments, furthermore we were capable of classifying the present organisms with an average classification accuracy of over 87%.

Biochemical Interactions through Microscopic Techniques: Structural and Molecular Characterization

Many researchers and scientists have contributed significantly to provide structural and molecular characterizations of biochemical interactions using microscopic techniques in the recent decade, as these biochemical interactions play a crucial role in the production of diverse biomaterials and the organization of biological systems. The properties, activities, and functionalities of the biomaterials and biological systems need to be identified and modified for different purposes in both the material and life sciences. The present study aimed to review the advantages and disadvantages of three main branches of microscopy techniques (optical microscopy, electron microscopy, and scanning probe microscopy) developed for the characterization of these interactions. First, we explain the basic concepts of microscopy and then the breadth of their applicability to different fields of research. This work could be useful for future research works on biochemical self-assembly, biochemical aggregation and localization, biological functionalities, cell viability, live-cell imaging, material stability, and membrane permeability, among others. This understanding is of high importance in rapid, inexpensive, and accurate analysis of biochemical interactions.

ATP Bioluminescence for Rapid and Selective Detection of Bacteria and Yeasts in Wine

Microbial contamination may represent a loss of money for wine producers as several defects can arise due to a microorganism’s growth during storage. The aim of this study was to implement a bioluminescence assay protocol to rapidly and simultaneously detect bacteria and yeasts in wines. Different wines samples were deliberately contaminated with bacteria and yeasts at different concentrations and filtered through two serial filters with decreasing mesh to separate bacteria and yeasts. These were resuscitated over 24 h on selective liquid media and analyzed by bioluminescence assay. ATP measurements discriminated the presence of yeasts and bacteria in artificially contaminated wine samples down to 50 CFU/L of yeasts and 1000 CFU/L of bacteria. The developed protocol allowed to detect, rapidly (24 h) and simultaneously, bacteria and yeasts in different types of wines. This would be of great interest for industries, for which an early detection and discrimination of microbial contaminants would help in the decision-making process.

An alternative sterility assessment for parenteral drug products using isothermal microcalorimetry

AIMS

Production and release of injectable drug solutions are highly regulated since the administration of injectables bypasses natural body barriers. The sterility test is the last opportunity of product quality assessment. However, sterility is currently assessed by visual inspection (VI) that is time consuming and somewhat subjective. Therefore, we assessed isothermal microcalorimetry (IMC) as a replacement for the VI of the filtration based state-of-the-art sterility control.

METHODS AND RESULTS

We used ATCC strains and house isolates to artificially contaminate frequently produced monoclonal antibodies (Avastin, Mabthera, Herceptin). After filtration, growth was assessed with IMC. Growth of all micro-organisms was reliably and reproducibly detected 4 days after inoculation, which was significantly faster than with VI.

CONCLUSIONS

The reliability and the sensitivity of IMC have a large potential to improve sterility controls. Further evaluation of this alternative method is therefore highly recommended.

SIGNIFICANCE AND IMPACT OF THE STUDY

Drug safety is of great concern for public health. Faster and safer drug production could be achieved using the technique described here. All the tests were performed with real manufactured drugs and complied with pharmaceutical standards. This suggests that drug sterility testing can be improved with potentially increased safety and cost reduction.

Bioluminescence assay for cell viability

Theoretical aspects of the adenosine triphosphate bioluminescence assay based on the use of the firefly luciferin-luciferase system are considered, as well as its application for assessing cell viability in microbiology, sanitation, medicine, and ecology. Various approaches for the analysis of individual or mixed cultures of microorganisms are presented, and capabilities of the method for investigation of biological processes in live cells including necrosis, apoptosis, as well as for investigation of the dynamics of metabolism are described.

Fluorescence-based rapid detection of microbiological contaminants in water samples

Microbiological contamination of process waters is a current issue for pharmaceutical industries. Traditional methods require several days to obtain results; therefore, rapid microbiological methods are widely requested to shorten time-to-result. Milliflex Quantum was developed for the rapid detection and enumeration of microorganisms in filterable samples. It combines membrane filtration to universal fluorescent staining of viable microorganisms. This new alternative method was validated using European and United States Pharmacopeia definitions, with sterile water and/or sterile water artificially contaminated with microorganisms. The Milliflex Quantum method was demonstrated to be reliable, robust, specific, accurate, and linear over the whole range of assays following these guidelines. The Milliflex Quantum system was challenged to detect natural contaminants in different types of pharmaceutical purified process waters. Milliflex Quantum was demonstrated to detect accurately contaminants 3- to 7-fold faster than traditional membrane filtration method. The staining procedure is nondestructive allowing downstream identification following a positive result. The Milliflex Quantum offers a fast, sensitive, and robust alternative to the compendial membrane filtration method.

Evaluation of growth based rapid microbiological methods for sterility testing of vaccines and other biological products

Most biological products, including vaccines, administered by the parenteral route are required to be tested for sterility at the final container and also at various stages during manufacture. The sterility testing method described in the Code of Federal Regulations (21 CFR 610.12) and the United States Pharmacopoeia (USP, Chapter <71>) is based on the observation of turbidity in liquid culture media due to growth of potential contaminants. We evaluated rapid microbiological methods (RMM) based on detection of growth 1) by adenosine triphosphate (ATP) bioluminescence technology (Rapid Milliflex(®) Detection System [RMDS]), and 2) by CO(2) monitoring technologies (BacT/Alert and the BACTEC systems), as alternate sterility methods. Microorganisms representing Gram negative, Gram positive, aerobic, anaerobic, spore forming, slow growing bacteria, yeast, and fungi were prepared in aliquots of Fluid A or a biological matrix (including inactivated influenza vaccines) to contain approximately 0.1, 1, 10 and 100 colony forming units (CFU) in an inoculum of 10 ml. These preparations were inoculated to the specific media required for the various methods: 1) fluid thioglycollate medium (FTM) and tryptic soy broth (TSB) of the compendial sterility method (both membrane filtration and direct inoculation); 2) tryptic soy agar (TSA), Sabouraud dextrose agar (SDA) and Schaedler blood agar (SBA) of the RMDS; 3) iAST and iNST media of the BacT/Alert system and 4) Standard 10 Aerobic/F and Standard Anaerobic/F media of the BACTEC system. RMDS was significantly more sensitive in detecting various microorganisms at 0.1CFU than the compendial methods (p<0.05), whereas the compendial membrane filtration method was significantly more sensitive than the BACTEC and BacT/Alert methods (p<0.05). RMDS detected all microorganisms significantly faster than the compendial method (p<0.05). BacT/Alert and BACTEC methods detected most microorganisms significantly faster than the compendial method (p<0.05), but took almost the same time to detect the slow growing microorganism P. acnes, compared to the compendial method. RMDS using SBA detected all test microorganisms in the presence of a matrix containing preservative 0.01% thimerosal, whereas the BacT/Alert and BACTEC systems did not consistently detect all the test microorganisms in the presence of 0.01% thimerosal. RMDS was compatible with inactivated influenza vaccines and aluminum phosphate or aluminum hydroxide adjuvants at up to 8 mg/ml without any interference in bioluminescence. RMDS was shown to be acceptable as an alternate sterility method taking 5 days as compared to the 14 days required of the compendial method. Isolation of microorganisms from the RMDS was accomplished by re-incubation of membranes with fresh SBA medium and microbial identification was confirmed using the MicroSEQ Identification System. BacT/Alert and BACTEC systems may be applicable as alternate methods to the compendial direct inoculation sterility method for products that do not contain preservatives or anti-microbial agents.

Detection of microbial contaminants in mammalian cell cultures using a new fluorescence-based staining method

AIMS

Microbial contamination of cell culture production processes is a current concern for biopharmaceutical industries. Traditional testing methods require several days to detect contamination and may advantageously be replaced by a rapid detection method. We developed a new method combining membrane filtration to microcolonies fluorescence staining method (MFSM) and compared it to epifluorescence microscopy.

METHODS AND RESULTS

Both methods were used to detect bacteria in CHO cells cultures. The epifluorescence microscopy showed to be limited by filterability, media interference and nonrobustness issues, whereas MFSM enabled consistent detection of Bacillus cereus, Staphylococcus epidermidis and Propionibacterium acnes after, respectively, 8, 9 and 48 h of incubation. Thanks to the nondestructive feature of the MFSM, stained membranes could be reincubated on culture media to yield visible colonies used for identification.

CONCLUSIONS

The new method described in this study showed its ability to detect microbial contaminants in cell culture samples with time-to-results from 2-5 times shorter than the traditional testing method.

SIGNIFICANCE AND IMPACT OF THE STUDY

The MFSM can be used as monitoring tool for cell cultures to significantly shorten detection times of microbial contamination, while preserving the ability to identify the contaminants and their viability.

Development of a nondestructive fluorescence-based enzymatic staining of microcolonies for enumerating bacterial contamination in filterable products

AIMS

Develop a nondestructive fluorescence-based staining procedure to rapidly detect and enumerate bacteria in filterable samples.

METHODS AND RESULTS

The study consists in the development of a staining solution and a protocol to fluorescently detect microcolonies on cellulose membranes. After detection, membranes can be re-incubated on media to yield colonies. Carboxyfluorescein diacetate was selected among other carboxyfluorescein derivatives for its staining efficiency and the absence of background. Several permeabilizers were evaluated for their ability to promote dye uptake into cells without affecting viability. We demonstrated that a combination of n-Octyl β-D-glucopyranoside, sodium hexametaphosphate, lithium chloride and rubidium chloride significantly increased the staining efficiency of bacteria without affecting their viability. The method developed allowed the detection in <9 h of all tested aerobic bacteria and in 48 h of the anaerobic slow grower Propionibacterium acnes.

CONCLUSIONS

This method allows the rapid detection of bacteria in filterable samples in at least three to five times faster than traditional microbiological method.

SIGNIFICANCE AND IMPACT OF THE STUDY

The advantage of this nondestructive procedure is to allow contaminants identification after membrane re-incubation. This method could be easily applied in routine in pharmaceutical, clinical and food and beverage industries to monitor contaminations.