Sterilizing benches and equipment with 70 percent ethanol, 10 percent sodium hypochlorite (minimum 10 min contact time) followed by sterile water, 1 M hydrogen chloride, and/or UV light.Maintaining dedicated equipment within each area, such as tubes, pipette tips, pipette guns, vortexers, and microcentrifuges.Using gentle, precise, and controlled pipetting and avoiding spills.Preparing single-use aliquots of reagents.Removing watches, wrist bands, and jewelry.Keeping all sample and reagent vessels sealed for as long as possible and using aseptic techniques when opening bottles and tubes.If contamination is continuously affecting the results of certain PCRs, despite appropriate measures, more stringent techniques can be applied. For example, being able to open and use tubes with one hand and without setting the cap on the bench and preventing pipette tips from touching solid surfaces. Good laboratory practice and aseptic techniques can be used to minimize contaminants affecting PCR.Īlthough the stringent aseptic techniques used in microbiology are usually unnecessary for PCR, adopting some of the practices can help eliminate contaminant transfer. The use of swinging doors that can be opened without using your hands and that also ensure the unidirectional flow of personnel.The availability of dedicated lab coats for use in each area.The application of fresh gloves before moving from area to area.Further strategies to avoid contaminants moving between the areas include: Maintaining a unidirectional flow of traffic between these areas is recommended. If possible, separate areas or rooms should be allocated to preprocessing, PCR amplification, and post-PCR steps to avoid cross-contamination. Contaminated pipettes, overuse of disposable tips, use of non-sterile tubes, glass wear, etc.Contaminants in reagents used in the PCR reaction.Contaminants on lab coats, watches, hair, skin, etc.Aerosols-microscopic droplets of fluid introduced into the air through spillages, overly energetic pipetting, careless vortexing, high ambient temperatures, etc.Sources of contamination include laboratory personnel and cross-contamination from positive samples or positive controls. The vast majority of false positive results can be avoided using strict laboratory hygiene practices, good pipetting techniques, and sterile labware, and the allocation of dedicated PCR stations or rooms. Preventing false positivesĮnsuring good laboratory practice and strict adherence to protocols are fundamental to minimizing erroneous PCR results. Fortunately, compared to other methods, false positives and negatives in PCR tests are relatively uncommon, and various steps and safeguards can be taken to prevent, detect, and mitigate these errors. A false diagnosis of Lyme’s disease, probably resulting from sample contamination, reportedly led to the death of a 30-year-old patient who received extensive antibiotic therapy and subsequently developed a Candida complication related to her prolonged catheterization. However, the life of the patient can also be put at risk in some cases. Therefore, a false negative result from group testing could mean several patients remain undiagnosed.Ī false positive result more often results in wasted time and medical resources and may cause unnecessary psychological distress to the person being diagnosed.
When using this method, samples from a number of patients are mixed into one test pool, and the individual samples are only tested when a positive result for the pool is discovered. This is a particular problem when a lab is using a group testing or pooled testing method to save time and resources. In the case of a contagion, such as COVID-19, a false negative can result in an infected person freely contacting uninfected individuals, rather than being quarantined and treated, accelerating the spread of the pathogen. False negatives can lead to a missed or late diagnosis, putting a patient’s health and survival at risk, while false positives can result in unnecessary additional tests and treatment, including unnecessary costs. False negative and false positive results are unfavorable outcomes of the remarkably high sensitivity and specificity of PCR tests, and they can have serious consequences in clinical testing.
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