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1 Coping with plate debris in colony counting
The analysis of agar plates for colonies in microbiology is frequently made challenging by the presence of debris and other unwanted material, either embedded within or on the surface of the agar. For manual counting, depending upon the level of experience of the individual involved, this can cause problems in terms of counting errors and loss of valuable laboratory time. In a busy laboratory environment, such activities can waste many hours of otherwise profitable working time during each day.
2 ProtoCOL provides accurate GLP compliant results for fast assessment of anti-microbial therapies in clinical trials
With the rush to get new anti-microbial therapies on the market to treat biological terrorism threats such as anthrax, methods of saving time at the clinical trial stage without compromising on accuracy are becoming increasingly important. Many new treatments for diseases caused by bacteria or yeasts concentrate on reducing or removing these micro-organisms from the affected area. Since colony enumeration provides the data on which product efficacy for most anti-microbial therapies is based, it is essential to obtain the most precise colony counts possible.
3 ProtoCOL - the essential tool for microbial quality control
Many microbial QC departments have a small team of people and yet are faced with the prospect of having to examine thousands of food samples every year for common contaminants such as Salmonella, E.coli 0157, Bacillus cereus, Listeria monocytogenes and Campylobacter. The majority of these samples prove negative with around 99.9 per cent being pathogen free. However, in a food poisoning outbreak a QC department has to test a large number of samples very quickly to help pinpoint the source of contamination. This is to ensure that those infected can be given the most effective treatment and the offending food can be withdrawn from sale to prevent further cases occurring.
4 Rapid quality control of viral vaccines
Internationally, a large number of adults and children are routinely vaccinated to protect them against a range of diseases. Many of these vaccines consist of an inactivated strain of a virus that causes the disease. If the concentration of the viral vaccine is incorrect then the protection may be insufficient, which could prove fatal among some of the more vulnerable groups inoculated. In the case of influenza vaccines, the tests for vaccine concentration must also be performed quickly because there is little time available to produce and test the vaccine before the next influenza season begins.
5 Automating quality control of milk
Across the developed world, billions of gallons of milk are destroyed every year due, in part, to microbial contamination problems. Most dairy QC laboratories test for a range of microorganisms including E.coli, indicating faecal contamination, Psychrophilic bacteria (these break down milk proteins to produce putrid and off flavours) and more dangerous pathogens such as Listeria monocytogenes, a causal agent of bacterial meningitis. The laboratories also test for Mycoplasma, Staphylococcus, Streptococcus and Pseudomonas spp., which are all indicative of mastitis in the dairy herd. If milk is infected with significant numbers of any of these organisms, it is destroyed to protect public health.
6 Automated colony counting for molecular biologists
A count of recombinant colonies or plaques is often used as the criteria for determining if the transformation efficiency is sufficient to continue working on a particular set of clones. One commonly used method of selecting for recombinants involves only growing cells that have a specific gene. For example, resistance to a particular antibiotic such as tetracycline or ampicillin conferred on them by the vector they have been transformed with. The other popular selection system is to clone into a gene within the vector thus inactivating that gene in the recombinants. This generally results in a visible colour change in the recombinant colonies or plaques. For instance, cloning into the LacZ gene in a pUC-based vector will prevent the expression of the LacZ gene product (-galactosidase). If X-gal (5-bromo-4-chloro-3-indolyl-β-D-galactoside) is added to the media, those clones which have an active -galactosidase will cleave it to produce blue (non-recombinant) colonies or plaques. The recombinants that cannot express an active -galactosidase are unable to breakdown X-gal and therefore, remain as white colonies or plaques.
7 Maintaining sterility in pharmaceutical manufacturing
At major pharmaceutical manufacturing facilities, microbiology Quality Control (QC) departments are responsible for testing tens of thousands of samples per month. These samples, often from several sites, are used to assess the sterility levels of, for example, the air in the plant or the water used to produce the pharmaceuticals. Most pharma companies operate an index system of acceptable levels of contamination, based on established international quality standards. This index ranges from 1 c.f.u (colony forming unit) /ml in critical samples such as the pharmaceutical products to 100 c.f.u/ml in the water used for production.
8 How to validate an aCOLyte automated colony counter to ensure accuracy in a quality control environment
Colony counts provide the data on which the effectiveness of essential products such as anti-microbial drug treatments or bactericidal disinfectants is based. Therefore, when quality controlling these products, it is vital to accurately enumerate colonies.
9 Using ProtoCOL for rapid assessment of the OPKA assay
Streptococcus pneumoniae is a major cause of pneumonia in young children and the elderly. New vaccines against this bacterium are required because conventional antibiotics are becoming less effective due to the increasing numbers of multi drug-resistant S. pneumoniae. To evaluate novel pneumococcal vaccines, an enzyme-linked immunosorbent assay (ELISA) is commonly used alongside a modified in vitro opsonophagocytic-killing assay (OPKA). The ELISA method allows antibody quantitation but cannot distinguish between functional and non-functional antibodies. The OPKA is useful as an additional test for measuring antibody function and is a good surrogate assay for immune protection. Patient blood samples are taken before and after vaccination, serially diluted and tested by OPKA and plated out onto Todd-Hewitt agar plates with yeast extract. An agar overlay containing antibiotics and 2, 3, 5-triphenyl tetrazolium chloride dye is added and the resulting red bacterial colonies are counted the next day to determine the dilution of patient serum that kills 50% of bacteria compared to the control (no serum). This method evaluates the killing function of the antibody induced following vaccination. Multiplexing is possible by use of antibiotic resistant strains of S. pneumoniae.
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