Non-Microbiological Mycobacterial Detection Techniques for Quality Control of Biological Products: A Comprehensive Review

Mycobacteria can be one of the main contaminants of biological products, and their presence can have serious consequences on patients' health. For this reason, the European Pharmacopoeia mandates the specific testing of biological products for mycobacteria, a critical regulatory requirement aimed at ensuring the safety of these products before they are released to the market. The current pharmacopeial reference, i.e., microbial culture method, cannot ensure an exhaustive detection of mycobacteria due to their growth characteristics. Additionally, the method is time consuming and requires a continuous supply of culture media, posing logistical challenges. Thus, to overcome these issues, pharmaceutical industries need to consider alternative non-microbiological techniques to detect these fastidious, slow-growing contaminating agents. This review provides an overview of alternative methods, which could be applied within a quality control environment for biological products and underlines their advantages and limitations. Nucleic acid amplification techniques or direct measurement of mycobacteria stand out as the most suitable alternatives for mycobacterial testing in biological products.

Barriers to the Use of Recombinant Bacterial Endotoxins Test Methods in Parenteral Drug, Vaccine and Device Safety Testing

The Bacterial Endotoxins Test (BET) is a critical safety test that is used to detect bacterial endotoxins, which are the major contributor to fever-inducing contamination risks known as pyrogens. All parenteral therapies, including every lot of injected drugs, vaccines, medical devices, must be tested for pyrogens to ensure patient safety. Bacterial endotoxins test methods were developed as a highly sensitive detection method for bacterial endotoxins, after the discovery of a clotting cascade in horseshoe crab blood. However, horseshoe crab species are limited to some inshore coastal habitats along the Atlantic coast of the USA and others throughout Asia. Fully functional horseshoe crab clotting factors can be manufactured via recombinant protein production, and several BET methods featuring recombinant horseshoe crab proteins have now been developed for commercial use. Recombinant Bacterial Endotoxins Test (rBET) methods based on the use of recombinant Factor C (rFC) were established in the European Pharmacopoeia - however, these methods have not yet been granted compendial status in the United States Pharmacopoeia (USP). In order to facilitate dialogue between stakeholders, the Physicians Committee for Responsible Medicine hosted two virtual roundtable discussions on the perceived barriers to the use of rBET methods for US FDA requirements. Stakeholders agreed that multiple rFC-based methods have been demonstrated to have suitable analytical performance, as described in ICH Q2 on the Validation of Analytical Procedures and USP <1225> on the Validation of Compendial Procedures. United States Pharmacopoeia compendial inclusion of the rFC-based and other rBET methods was favoured, in order to reduce the additional burdens created by a lack of global harmonisation on BET testing requirements.

Comparison of bacterial endotoxin testing methods in purified pharmaceutical water matrices

Current bacterial endotoxin testing systems can be labor-intensive and time-consuming, involving several manual pipetting steps. In our quality control laboratory, annually, we test about 15,000 samples of different grades of purified water, WFI and water samples taken to validate cleaning procedures for endotoxins. We are currently using the Kinetic-QCL™ assay which is a pharmacopeia method that provides reliable results. We compared this assay with another Limulus amebocyte lysate (LAL)-based assay (Endosafe®-MCS) and an alternative endpoint fluorescent recombinant Factor C (rFC) assay (ENDOZYME II GO®). Both these assays have been developed to reduce analyst preparation time. Our objective was to assess if they could increase the throughput of our testing while maintaining low rates of invalid results. The results demonstrated that the two most appropriate methods for rapid endotoxin detection in water are our current assay, K-QCL, and the rFC-based assay, ENDOZYME II GO. This latter assay was found to be less sensitive to interference than our current assay, particularly in cleaning validation water samples. It also showed better performance, accuracy, repeatability and had a shorter time-to-results. ENDOZYME II GO assay allows quick testing of large numbers of samples with reliable results and is a good alternative for conventional LAL assays.

Comparison of Limulus Amoebocyte Lysate and Recombinant Factor C Assays for Endotoxin Detection in Four Human Vaccines with Complex Matrices

Endotoxins, heat-stable lipopolysaccharides from Gram-negative bacteria, are potential contaminants that can be introduced during manufacturing of pharmaceutical products, including vaccines. Parental pharmaceutical products undergo endotoxin testing because endotoxins are pyrogenic in humans and can induce severe physiological reactions. Currently, animal-derived Limulus amoebocyte lysate (LAL) assays are widely used. Assays using recombinant factor C (rFC), a nonanimal-derived reagent, have been proposed as alternatives. Some components in the matrices of pharmaceutical products can interfere with these assays. We compared two LAL- and two rFC-based assays for endotoxin detection in four complex human vaccine matrices. We showed that the results for the rFC-based assays were at least equivalent to those for the LAL-based assays, although the rFC-based assays were found to be adequate but slightly less suitable for one of the products that contained proteases as the methods used to inactivate the proteases reduced the assay performance. Likewise, LAL was adequate but less suitable for another product that contained glucans. The rFC assays offer a number of benefits, including compliance with the principles of the 3Rs, i.e., replacement, reduction, and refinement of animal testing by safeguarding animal welfare and promoting more ethical and sustainable use of animals for testing. After they are fully validated, as per the compendial requirements, they could be considered as suitable replacement assays for the detection of endotoxin in the manufacturing processes of pharmaceutical products. In summary, we demonstrated that both LAL and rFC assays are adequate for testing and releasing four vaccine products.

Catchment source contributions to the sediment-bound organic matter degrading salmonid spawning gravels in a lowland river, southern England

The ingress of particulate material into freshwater spawning substrates is thought to be contributing to the declining success of salmonids reported over recent years for many rivers. Accordingly, the need for reliable information on the key sources of the sediment problem has progressed up the management agenda. Whilst previous work has focussed on apportioning the sources of minerogenic fine sediment degrading spawning habitats, there remains a need to develop procedures for generating corresponding information for the potentially harmful sediment-bound organic matter that represents an overlooked component of interstitial sediment. A source tracing procedure based on composite signatures combining bulk stable (13)C and (15)N isotope values with organic molecular structures detected using near infrared (NIR) reflectance spectroscopy was therefore used to assess the primary sources of sediment-bound organic matter sampled from artificial spawning redds. Composite signatures were selected using a combination of the Kruskal-Wallis H-test, principal component analysis and GA-driven discriminant function analysis. Interstitial sediment samples were collected using time-integrating basket traps which were inserted at the start of the salmonid spawning season and extracted in conjunction with critical phases of fish development (eyeing, hatch, emergence, late spawning). Over the duration of these four basket extractions, the overall relative frequency-weighted average median (±95% confidence limits) source contributions to the interstitial sediment-bound organic matter were estimated to be in the order: instream decaying vegetation (39±<1%; full range 0-77%); damaged road verges (28±<1%; full range 0-77%); septic tanks (22±<1%; full range 0-50%), and; farm yard manures/slurries (11±<1%; full range 0-61%). The reported procedure provides a promising basis for understanding the key sources of interstitial sediment-bound organic matter and can be applied alongside apportionment for the minerogenic component of fine-grained sediment ingressing the benthos. The findings suggest that human septic waste contributes to the interstitial fines ingressing salmonid spawning habitat in the study area.