MRSA ā Emerging Therapeutic & Screening Approaches
MRSA ā Emerging Therapeutic & Screening Approaches
Staphylococcus aureus is a gram positive, commensal bacteria found in normal human flora on the skin and mucous membranes. The commensal nature of this organism results in colonisation of around half of the general population, rising to around 80% in populations of healthcare workers, hospitalised patients and the immunocompromised1. However, given the opportunity to colonise internal tissues or the bloodstream, S. aureus infection can cause serious disease. Skin conditions caused by S. aureus include impetigo, scalded skin syndrome, boils, and abscesses. Examples of more serious conditions include meningitis, pneumonia, endocarditis, bacteraemia, and sepsis2.
Antimicrobial resistance (AMR) has, and continues to be, one of the largest threats to global health. In 2019, it is estimated that 1.27 million deaths globally were directly attributed to AMR, based on the drug-susceptible counterfactual, with only ischaemic heart disease and stroke accounting for more deaths in that year1. Figure 1 shows a global distribution map of MRSA isolates from the data of this comprehensive study. Methicillin-resistant Staphylococcus aureus (MRSA) was first identified only one year after the introduction of the penicillin-like antibiotic, methicillin3. While methicillin is no longer used in clinical practice, the term MRSA is used to encompass resistance to commercially available antibiotics such as β-lactams3. For many years, much work has gone into seeking novel therapies to combat drug-resistant bacteria, however, the indiscriminate overuse of antibiotics seen around the world, along with other factors, continues to contribute to the rise in AMR.
Identification of drug-resistant strains of bacteria is crucial to allow for characterisation of the pathogen and correct treatment of the infection. Classical evaluation consists of a routine culture to verify a diagnosis based on presenting symptoms. However, this can be a time consuming and laborious process which may delay diagnosis and treatment of a potentially fatal infection1.
Methicillin-Resistant Staphylococcus aureus
Methicillin is of a class of antibiotics known as β-lactams which bind to the penicillin binding protein (PBP) of the bacteria. PBP is responsible for crosslinking between N-acetylmuramic acid and N-acetylglucosamine which forms the architecture of the bacterial cell wall. When β-lactams bind to the PBP, a build-up of peptidoglycan precursors triggers autolytic digestion of peptidoglycan, facilitated by hydrolase. This reduction in peptidoglycans results in the loss of the integrity of the bacterial cell wall and ultimately culminates in cell damage caused by high internal osmotic pressure.
While methicillin has lost its clinical utility due to the emergent resistance, MRSA is used to describe S. aureus which displays resistance to penicillin-like antibiotics such as amoxicillin and oxacillin, as well as other forms of commercially available antibiotics like macrolides, tetracyclines, and fluroquinolones4. A meta-analysis by Dadashi et al., showed that 43% of S. aureus isolates where methicillin-resistant, exhibiting the prevalence of MRSA5.
Transmission is possible from direct contact with an infected individual or through contact with fomites2. MRSA infections can be categorised as either community acquired infections (CA-MRSA), or hospital acquired infections (HA-MRSA). While rates of HA-MRSA have fallen over the last ten years, this decrease in infection rates has not translated to CA-MRSA6. This is evidence of the requirement for quicker, easier testing in community settings to identify those infected by MRSA and to trigger the initiation of isolation and treatment.
While the pathophysiology of MRSA will largely depend on the causative strain of bacteria, collectively, S. aureus is the most common bacterial infection in humans and may result in infections of varying severity including1:
- Bacteraemia
- Infective endocarditis
- Skin and soft tissue infections
- Osteomyelitis
- Septic arthritis
- Prosthetic device infections
- Pulmonary infections
- Gastroenteritis
- Meningitis
- Toxic shock syndrome
- UTIs
Development of resistance and resistance mechanisms
Antimicrobial resistance arises from a combination of mechanisms. Genetic mutations are crucial in the development of resistance mechanisms. These genetic mutations must favour the survival of the mutated gene and the advantage of AMR mechanisms to the survival of bacteria cannot be understated. Regarding MRSA, S. aureus can gain resistance through horizontal gene transfer mediated by plasmids, mutations in chromosomal genes or mobile genetic elements4. Methicillin-susceptible Staphylococcus aureus (MSSA) gains the staphylococcal cassette chromosome (SCCmec) gene, a gene containing mecA, which is responsible for some of the resistance mechanisms displayed by MRSA4. The collection of antibiotics the bacteria gains resistance to, will depend on the SCCmec gene type.
The first mechanism of resistance is the expression of β-lactamase which functions to degrade β-lactams, ultimately resulting in loss of function of the antibiotic. This enzyme hydrolyses β-lactam ions in the periplasmic space, denaturing the antibiotic before it can interact with bacteria3. The mecA gene encodes the protein penicillin-binding protein 2a (PBP-2a), a type of PBP which has lower affinity for β-lactams, as well as other penicillin-like antibiotics due its conformation, meaning that the presence of these antimicrobial agents does not confer a loss of structure in the bacterial cell wall1.
One study conducted by Hosseini et al., investigated resistance mechanisms in MRSA and showed that all multidrug resistance MRSA strains displayed biofilm formation as part of its resistance strategy7. Biofilms induce resistance to high concentrations and a large variety of antimicrobial agents and help regulate anti-bacterial immune responses. Biofilm formation is mediated by the protein, polysaccharide intercellular adhesin (PIA). Furthermore, MRSA strains which display biofilm formation are associated with more severe and more virulent infections7.
Current and Emerging Therapeutic Strategies
Other types of antibiotics have been used to treat MRSA infections over the years. Vancomycin has been used to combat infections resistant to penicillin-like antibiotics as they display a different mode of action. Vancomycin inhibits peptidoglycan synthesis by forming hydrogen bonds within the structure of peptidoglycan precursors2. While this strategy has proven effective for past 50 years, more and more strains are displaying vancomycin resistance in addition to resistance to penicillin-like antibiotics8. One study by Deyno et al., estimates the prevalence of vancomycin-resistant S. aureus in Ethiopia to be around 11% 4. Daptomycin is another antibiotic which has been shown to be effective in MRSA treatment. This cyclic lipopeptide binds to the bacterial membrane, resulting in cell death9.
Due to the decreasing number of available, effective antibiotics, novel therapeutic strategies are required to combat MRSA infection. One of the most promising approaches uses antimicrobial peptides (AMPs). AMPs are naturally occurring molecules of the innate immune system and have one of two mechanisms of action: membranolytic action and non-membranolytic action. AMPs normally consist of and amphipathic or cationic structure, between 5-50 amino acids long. Naturally occurring AMPs have been used as a model to develop synthetic AMPs, designed to neutralise the limitations of natural AMPs boasting an improved half-life and improved antimicrobial properties3. Membrane disruptive AMPs can be further categorised by mechanism of action. The first is the Toroidal-pore model in which AMPs form vertical pores in the bacterial membrane causing a change in conformation of the lipid head. Next is the Barrel-stave mode, in which AMPs bind to the bacterial membrane and aggregate before breaching the cell wall causing uncontrolled cell movement, resulting in cell death3. Finally, in the carpet model, the membrane is destroyed in a detergent-like action where the AMPS arrange on the cell membrane with their hydrophobic part facing the phospholipid bilayer, altering the surface tension of the membrane. This eventually results in the formation of micelles and the destruction of the bacterial membrane3.
Non-membrane disruptive AMPs require much more investigation; however, it is accepted that these AMPs enter the cell, reacting with important intracellular components inhibiting protein and nucleic acid synthesis, cell division and protease activity3.
Silver nanoparticles (AgNPs) exhibit broad spectrum antimicrobial properties through various mechanisms of action. These nanosized particles boast increased antimicrobial properties due to an increased surface area per volume ratio. The first mechanism of action to note is AgNPs direct adhesion to the bacterial membrane, which alters the structural integrity of the membrane, allowing the AgNPs to penetrate the cell, wreaking havoc on the intracellular components until it loses the ability to carry out essential cellular processes3.
Once the AgNPs aggregate on the bacterial surface, the difference in electrostatic charge, driven by the positive charge displayed by the AgNPs and negatively charged bacteria, pit formation occurs on the cell surface, inhibiting vital cellular movement, resulting in cell death3. AgNPs may also inhibit protein synthesis by denaturing ribosomes and directly interacting with DNA. This interaction can cause denaturing of the DNA helix and ultimately result in cell death3. Finally, AgNPs can induce the production of reactive oxygen species (ROS) and free radicals. The molecules cause irreversible cell damage to the bacteria3.
While AMPs and AgNPs each possess individual limitations such as toxicity and instability, studies show that a combination of these therapeutic strategies can overcome these issues, stabilising the antimicrobial agents to their respective target sites3.
Screening, Testing & Evaluation
Classical determination of MRSA and other bacterial infections consists of obtaining a patient sample and growing colonies from the patient sample in culture. These cultures can then be investigated under a microscope and characterised, allowing diagnosis and the initiation of treatment. Whilst effective, these methods are time consuming and laborious, taking up to three days for cultures to develop, somewhat limiting their utility for the diagnosis of potentially fatal infections.
New molecular rapid PCR microbiology techniques aid in the identification of bacterial strains through a three-step process involving extraction, amplification, and detection. These new methods allow for timely identification of infectious strains and AMR characterisation. Specific genes or sections of gene which are responsible for AMR can be detected, helping to achieve strain characterisation and aid physicians in prescribing the correct treatment plan. These methods improve test turnaround times to around one to two days and help to reduce the risk of costly human error and contamination.
Vivalytic MRSA/SA
Bosch Vivalytic MRSA/SA is an automated qualitative in vitro diagnostic test based on real-time PCR for the detection and differentiation of methicillin-resistant Staphylococcus aureus (MRSA) and Methicillin-sensitive Staphylococcus aureus (MSSA) DNA from human nasal- or oropharyngeal swabs to aid in the diagnosis of MRSA infection of symptomatic or asymptomatic individuals, providing results in less than 1 hour.
Without MRSA screening, many MRSA colonised patients remain unnoticed in hospitals and will not be isolated. Without Isolation many of these patients transfer the pathogen to at least one other patient during their hospital admission. PCR based screening is associated with high precision and fast time to results and is often used for early decisions on isolation and hygiene measures.
This POCT system provides fast, accurate characterisation of MRSA/SA strains while minimising the required user steps and reducing the need for expensive laboratory equipment helping physicians implement timely and effective treatments.
Detectable Pathogens:
- Methicillin-resistant Staphylococcus aureus
- Methicillin-sensitive Staphylococcus aureus
Specific Gene Targets:
- SCCmec/orfX junction
- MecA/MecC
- SA422
Some of the other benefits of this test include:
- Multiple sample types – Data shows that for approx. 13% of MRSA carriers, the pathogen is only located in the throat. Therefore, using throat swabs significantly increases the sensitivity of detection by approx. 26%.
- Broad MRSA Range – mecA or mecC are the genes responsible for resistance to β-lactam antibiotics. mecA/meC is part of the mobile genetic element Staphylococcal cassette chromosome mec (SCCmec). Vivalytic MRSA/SA can detect mecA as well as mecC and a broad variety of SCCmec elements which help to reduce false negative results.
- Fast time-to-result – Provides quick results in less than 1hr allowing quick decisions on therapies. Traditional culture time-to-result is 48-72hrs and laboratory PCR is 12-24hrs.
- This highly automated system minimises the user steps required to achieve a result while limiting the requirement for expensive lab equipment and sample transportation. Vivalytic MRSA/SA POCT test allow the implementation of treatment as soon as 1hr after sample collection.
References
- Murray CJ, Ikuta KS, Sharara F, et al. Global Burden of Bacterial Antimicrobial Resistance in 2019: A Systematic Analysis. The Lancet. 2022;399(10325):629-655. doi:https://doi.org/10.1016/S0140-6736(21)02724-0
- Nandhini P, Kumar P, Mickymaray S, Alothaim AS, Somasundaram J, Rajan M. Recent Developments in Methicillin-Resistant Staphylococcus aureus (MRSA) Treatment: A Review. Antibiotics. 2022;11(5):606. doi:https://doi.org/10.3390/antibiotics11050606
- Masimen MAA, Harun NA, Maulidiani M, Ismail WIW. Overcoming Methicillin-Resistance Staphylococcus aureus (MRSA) Using Antimicrobial Peptides-Silver Nanoparticles. Antibiotics. 2022;11(7):951. doi:https://doi.org/10.3390/antibiotics11070951
- Liu WT, Chen EZ, Yang L, et al. Emerging resistance mechanisms for 4 types of common anti-MRSA antibiotics in Staphylococcus aureus: A comprehensive review. Microbial Pathogenesis. 2021;156:104915. doi:https://doi.org/10.1016/j.micpath.2021.104915
- Dadashi M, Nasiri MJ, Fallah F, et al. Methicillin-resistant Staphylococcus aureus (MRSA) in Iran: A systematic review and meta-analysis. Journal of Global Antimicrobial Resistance. 2018;12:96-103. doi:https://doi.org/10.1016/j.jgar.2017.09.006
- Kourtis AP, Hatfield K, Baggs J, et al. Vital Signs: Epidemiology and Recent Trends in Methicillin-Resistant and in Methicillin-Susceptible Staphylococcus aureus Bloodstream Infections — United States. MMWR Morbidity and Mortality Weekly Report. 2019;68(9):214-219. doi:https://doi.org/10.15585/mmwr.mm6809e1
- Hosseini M, Shapouri Moghaddam A, Derakhshan S, et al. Correlation Between Biofilm Formation and Antibiotic Resistance in MRSA and MSSA Isolated from Clinical Samples in Iran: A Systematic Review and Meta-Analysis. Microbial Drug Resistance. Published online March 10, 2020. doi:https://doi.org/10.1089/mdr.2020.0001
- Verma R, Verma SK, Rakesh KP, et al. Pyrazole-based analogs as potential antibacterial agents against methicillin-resistance staphylococcus aureus (MRSA) and its SAR elucidation. European Journal of Medicinal Chemistry. 2021;212:113134. doi:https://doi.org/10.1016/j.ejmech.2020.113134
- Deyno S, Fekadu S, Astatkie A. Resistance of Staphylococcus aureus to antimicrobial agents in Ethiopia: a meta-analysis. Antimicrobial Resistance & Infection Control. 2017;6(1). doi:https://doi.org/10.1186/s13756-017-0243-7
Lipoprotein (a) Awareness Day 2023
Randox are raising awareness for Lipoprotein(a), we want to drive awareness on tests that are available to you to decrease the risk of stroke, heart attack or other heart diseases!
Lp(a) is a risk factor for atherosclerosis and related diseases including CHD and stroke. It is increasingly recognised as the strongest known genetic risk factor for premature coronary artery disease.
Identifying any possible health conditions that would relate to early signs of stroke, heart attack or other heart diseases will allow you to make any decisions on an appropriate diet, lifestyle changes and early treatment to reduce your risk of further problems.
Benefits of the Randox Lp(a) assay
WHO/IFCC Reference Material
Dedicated Five-Point Calibrator Available
Excellent Correlation
Excellent Precision
Liquid Ready-To-Use
Available in nmol/L
Applications Available-on Roche, Abbott, Beckman, and more.
The biggest challenge that exists surrounding Lp(a) measurement is the heterogeneity of the apo(a) isoforms, resulting in the underestimation or overestimation of Lp(a) concentrations. In immunoassays, the variable numbers of repeated KIV-2 units in Lp(a) act as multiple epitopes. This is where standardisation across calibrators is vital. Unless the calibrants do have the same range of isoforms as test samples, those with higher numbers of the KIV-2 repeat, will represent with an overestimation in Lp(a) concentrations and those with smaller numbers of the KIV-2 repeat, will represent with an underestimation. The smaller isoforms are strongly associated with higher Lp(a) concentrations. Lack of standardisation of the calibrant would result in an underestimation of Lp(a) associated CVD risk. It is important to note that an Lp(a) immunoassay employing isoform insensitive antibodies does not exist.
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Randox Sales Reps are experts in their fields and are available to discuss your specific requirements.
Simply send us an email by clicking the link below and we will get in touch!
Celebrating Lp(a) Awareness Day 2022 today!
Randox are raising awareness for Lipoprotein(a), we want to drive awareness on tests that are available to you to decrease the risk of stroke, heart attack or other heart diseases.
Lp(a) is a risk factor for atherosclerosis and related diseases including CHD and stroke. It is increasingly recognised as the strongest known genetic risk factor for premature coronary artery disease. The biggest challenge that exists surrounding Lp(a) measurement is the heterogeneity of the apolipoprotein(a) isoforms, resulting in the underestimation or overestimation of Lp(a) concentrations.
Benefits of the Randox Lp(a) assay
WHO/IFCC reference material – The Randox Lp(a) assay is calibrated in nmol/l and traceable to the WHO/IFCC reference material (IFCC SRM 2B) and provides an acceptable bias compared with the Northwest Lipid Metabolism Diabetes Research Laboratory (NLMDRKL) gold standard method.
Dedicated calibrator & control available – Five point calibrator with accuracy-based assigned target values (in nmol/l) is available, accurately reflecting the heterogeneity of the apo(a) isoforms. Dedicated Lp(a) control is available offering a complete testing package.
Excellent correlation – A correlation coefficient of r=0.995 was displayed when the Randox method was compared against other commercially available methods.
Excellent precision – The Randox Lp(a) assay displayed a within run precision of <2.54%.
Liquid ready-to-use – The Randox Lp(a) assay is available in a liquid ready-to-use format for convenience and ease-of-use.
Applications available – Instrument-specific settings can be provided for a wide range of clinical chemistry analysers.
The biggest challenge that exists surrounding Lp(a) measurement is the heterogeneity of the apo(a) isoforms, resulting in the underestimation or overestimation of Lp(a) concentrations. In immunoassays, the variable numbers of repeated KIV-2 units in Lp(a) act as multiple epitopes. This is where standardisation across calibrators is vital. Unless the calibrants do have the same range of isoforms as test samples, those with higher numbers of the KIV-2 repeat, will represent with an overestimation in Lp(a) concentrations and those with smaller numbers of the KIV-2 repeat, will represent with an underestimation. The smaller isoforms are strongly associated with higher Lp(a) concentrations. Lack of standardisation of the calibrant would result in an underestimation of Lp(a) associated CVD risk. It is important to note that an Lp(a) immunoassay employing isoform insensitive antibodies does not exist.
DID YOU KNOW?
Lp(a) has been identified to be a key risk factor for cardiovascular complications in individuals with COVID-19!
It is well documented that pre-existing comorbidities such as diabetes and CVD are associated with greater severity and higher fatality rates in those with COVID-19. Those with either baseline elevated Lp(a) or those whose Lp(a) levels increased following infection from COVID-19, or both, maybe at a significantly increased risk of developing thromboses. Elevated Lp(a) levels may cause acute destabilisation of pre-existing but quiescent, atherosclerotic plaques, which could induce an acute myocardial infarction or stroke.
Identifying any possible health conditions that would relate to early signs of stroke, heart attack or other heart diseases will allow you to make any decisions on an appropriate diet, lifestyle changes and early treatment to reduce your risk of further problems.
For more information about Lp(a):
Visit our website: Lipoprotein(a) [Lp(a)] | Reagents | Randox Laboratories
Or email: marketing@randox.com
Lp(a) Calibrator
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Superior Performance & Unique Tests
Superior Performance & Niche Reagents
Randox offer a range of high performance, unique and niche reagents that are designed to enhance your laboratory testing capabilities.
Our impressive portfolio of high performance & unique tests together with our standard assays sets us apart in the in vitro diagnostics market. Our superior performance reagents and methodologies deliver highly accurate and specific results, that can facilitate earlier diagnosis of disease states with confidence and precision.
Benefits of High Performance Reagents
Reduce Costs
We can help create cost-savings for your laboratory through excellent stability, eliminating the requirement for costly test re-runs. Our quality reagents also come in a range of different kit sizes to reduce waste and for your convenience.
Confidence in Patient Results
Our traceability of material and extremely tight manufacturing tolerances ensure uniformity across our reagent batches. All of our assays are validated against gold-standard methods.
Applications Available
Applications are available detailing instrument-specific settings for the convenient use of the Randox superior performance & unique assays on a wide variety of clinical chemistry analysers.
Superior Performance Offering
Randox offer an extensive range of 115 assays across routine and niche tests, and cover over 100 disease makers. Our high performance assays deliver superior methodologies, more accurate and specific results compared to traditional methods.
Reduce Labour
Reduce valuable time spent running tests. Randox reagents come in liquid ready-to-use formats and various kit sizes for convenient easy-fit. Barcode scanning capabilities for seamless programming.
Unique Offering
Our range of unique assays means that Randox are one of the only manufacturers to offer these tests in an automated biochemistry format.
The in vitro diagnostics market is continuously adapting to the changes in laboratory testing. Consequently, Randox have continued to reinvest in R&D to produce superior performance & unique tests offering laboratories choice, quality and innovation.
The Randox Lp(a) assay is calibrated in nmol/l and traceable to the WHO/IFCC reference material (IFCC SRM 2B) and provides an acceptable bias compared with the Northwest Lipid Metabolism Diabetes Research Laboratory (NLMDRKL) gold standard. A five-point calibrator with accuracy-based assigned target values (in nmol/l) is available, accurately reflecting the heterogeneity of the apo(a) isoforms.
The Randox bile acids test utilises an advanced enzyme cycling method which displays outstanding sensitivity and precision when compared to traditional enzymatic based tests. The Randox 5th Generation Bile Acids test is particularly useful in paediatrics where traditional bile acids tests are affected by haemolytic and lipaemic samples.
A superior assay from Randox, the vanadate oxidation method offers several advantages over the diazo method, including less interference by haemolysis and lipaemia, which is particularly evident for infant and neonatal populations.
The Randox Fructosamine assay utilises the enzymatic method which offers improved specificity and reliability compared to conventional NBT-based methods. The Randox enzymatic method does not suffer from non-specific interferences unlike other commercially available fructosamine assays.
Soluble transferrin receptor (sTfR) is a marker of iron status. In iron deficiency anaemia, sTfR levels are significantly increased, however remain normal in the anaemia of inflammation. Consequently, sTfR measurement is useful in the differential diagnosis of microcytic anaemia.
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Lp(a): For the Accurate Detection of CVD Risk
Lp(a) is an independent risk factor for cardiovascular disease (CVD), even when classical risk factors such as hypertension, elevated cholesterol, and diabetes have been taken into consideration. High levels of Lp(a) is a heredity condition, associated with complex mechanisms involving the proatherogenic and prothrombotic pathways (1).
Traditional CVD testing panel
According to the World Health Organisation (WHO), CVD is the leading cause of death globally, accounting for 31 percent of deaths, totalling 17.7 million deaths per year. 80 percent of all CVD deaths are attributed to heart attacks and strokes, equivalent to 1 in 4. Identifying those who are at a high risk of developing CVD and ensuring that they are receiving the appropriate treatment can prevent premature deaths (2).
The lipid profile is frequently used to assess an individual’s risk of CVD developing later in life. Routine tests to assess CVD risk include: triglycerides, high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C). LDL-C has been found to strongly correlate with CVD risk (3). NICE recommend measuring total cholesterol, HDL cholesterol, non-HDL cholesterol and triglycerides as the full lipid profile and then review other risk factors, including: age, diet, smoking, QRISK, co-morbidities to view risk and the management of risk (4). However, the current lipid panel needs to be adjusted to ensure that its utilisation is effective in meeting clinician and patient needs.
Lipoprotein(a)
Lipoprotein (a) or Lp(a) consists of two protein molecules, apolipoprotein (a) or apo(a) is covalently linked by a disulphide bond to the apolipoprotein B-100 or apoB-100 of a cholesterol-rich low-density lipoprotein or LDL like particle. Lp(a) is synthesised in the liver and is detectable in the bloodstream (5).
The structure of Lp(a) resembles that of the proteins involved in the breakdown of blood clots, plasminogen and tissue plasminogen activator (TPA). As a result, the biggest concern with Lp(a) is that it prohibits the ability of these proteins to break down blood clots by competing for the ‘binding to fibrin’, boosting the blood’s clotting ability within arteries, thus heightening the risk of heart attacks and strokes. Consequently, high levels of Lp(a) is characterised by atherosclerosis including coronary heart disease, peripheral vascular disease, aortic stenosis, thrombosis and stroke (6).
The Journal of the American Medical Association reviewed 36 studies in 2009 which assessed ‘the role of Lp(a) and vascular disease’ in 126,634 individuals. The study found that a 3.5-fold increase in Lp(a) levels was accompanied with a 13 percent higher risk of coronary heart events and a 10 percent higher risk of stroke (7).
Later, an Italian population study carried out on 826 individuals in 2014 found that elevated levels of Lp(a) is due to two different variations of the apo(a) gene which is determined by the kringle sequence differences at the apo(a) locus. The study found that individuals with one variation had a 50 percent greater risk of CVD, while individuals with both variations had 2.5 times greater risk (7).
According to the Lipoprotein Foundation (2015), based on genetic factors, from birth, one in five or 20% of individuals have high Lp(a) levels greater than 50mg/dL, with most blissfully unaware they have it. Overtime, high levels of Lp(a) gradually narrow the arteries, limiting blood supply to the brain, heart, kidneys and legs, increasing the risk of heart attacks and strokes (5).
Testing for high Lp(a) levels
The Lipoprotein (a) Foundation (2015) recommends that Lp(a) levels should be tested if:
- There is a family history of cardiovascular disease including stroke, heart attack, circulation problems in the legs and/or narrowing of the aorta, at a young age
- Stroke or heart attack if classical risk factors including high LDL-cholesterol, obesity, diabetes and smoking have been eliminated
- High levels of LDL-cholesterol following treatment with statins or other LDL lowering medications(5)
When selecting a Lp(a) assay, the Internal Federation of Clinical Chemistry (IFCC) (2004) Working Group on Lp(a) recommends that laboratories use assays that do not suffer from apo(a) size-related bias to minimise the potential risk of misclassification of patients for coronary heart disease (8).
The Lp(a) Foundation reference Marcovina and Albers (2016) in their recommendations for the best Lp(a) test. The study came to the following conclusions:
- Robust assays based on the Denka method, reportable in nanomoles per litre (nmol/L) are traceable to WHO/IFCC reference material
- Five-point calibrators with accuracy-based assigned target values will minimise the sensitivity of to the size of apo(a)
- Upon request, manufacturers should provide the certificate of evaluation of the calibrator and reagent lots with the relative expiration dates (9)
Benefits of the Randox Lp(a) assay
The Randox Lp(a) assay is one of the only methodologies on the market that detects the non-variable part of the Lp(a) molecule and so suffers minimal size related bias providing more accurate and consistent results. This methodology allows for the detection of Lp(a) in serum and plasma. The Randox Lp(a) kit is standardized to the WHO/IFCC reference material, SRM 2B, and is the closest in terms of agreement to the ELISA reference method.
A five-point calibrator is provided with accuracy-based assigned target values which accurately reflects the heterogeneity of isoforms present in the general population.
Liquid ready-to-use reagents are more convenient as the reagent does not need to be reconstituted, reducing the risk of errors.
Applications are available for a wide range of biochemistry analysers which details instrument-specific settings for the convenient use of the Randox Lp(a) assay on a variety of systems. Measuring units in nmol/L are available upon request.
References
- Li, Yonghong, et al. Genetic Variants in the Apolipoprotein(a) Gene and Coronary Heart Disease. Circulation: Genomic and Precision Medicine. [Online] October 2011. [Cited: April 24, 2018.] http://circgenetics.ahajournals.org/content/4/5/565.
- World Health Organisation. Cardiovascular Disease. [Online] 2017. [Cited: April 30, 2018.] http://www.who.int/cardiovascular_diseases/en/.
- Doc’s Opinion. Lipoprotein (a). [Online] 2013. [Cited: April 30, 2018.] https://www.docsopinion.com/health-and-nutrition/lipids/lipoprotein-a/.
- National Institutional for Health and Care Excellence. Cardiovascular disease: risk assessment and reduction, including lipid modification. [Online] July 2014. [Cited: April 30, 2018.] https://www.nice.org.uk/guidance/cg181/chapter/1-recommendations#lipid-modification-therapy-for-the-primary-and-secondary-prevention-of-cvd-2.
- Lipoprotein(a) Foundation. Understand Inherited Lipoprotein(a). [Online] 2015. [Cited: April 24, 2018.] http://www.lipoproteinafoundation.org/?page=UnderstandLpa.
- Heart UK. Lipoprotein (a). [Online] June 23, 2014. [Cited: April 24, 2018.] https://heartuk.org.uk/files/uploads/huk_fs_mfss_lipoprotein_02.pdf.
- Ashley, Robert. High lipoprotein(a) levels may indicate heart disease in some. The Brunswick News. [Online] March 05, 2018. [Cited: April 24, 2018.] https://thebrunswicknews.com/opinion/advice_columns/high-lipoprotein-a-levels-may-indicate-heart-disease-in-some/article_16ab1049-7a6f-5da0-8966-59e94ae31b6d.html.
- Dati, F; Tate, J R; Marcovina, S M; Steinmetz, A; International Federation of Clinical Chemistry and Laboratory Medicine; IFCC Working Group for Lipoprotein(a) Assay Standardization. First WHO/IFCC International Reference Reagent for Lipoprotein(a) for Immunoassay–Lp(a) SRM 2B. NCBI. [Online] 2004. [Cited: April 30, 2018.] https://www.ncbi.nlm.nih.gov/pubmed/15259385.
- Tsimikas, Sotirios. A Test in Context: Lipoprotein(a) – Diagnosis, Prognosis, Controversies, and Emergining Therapies. 6, s.l. : Elsevier, 2017, Vol. 69. 0735-1097.
If you are a cardiologist or a laboratory who are interested in running cardiology and lipid assays, Randox offer a wide range of high-quality, routine and niche assays including: adiponectin, H-FABP, sLDL, TxBCardio, HDL2/3-C, Homocysteine, Apo C-II, Apo C-III and Apo E. These can be run on most automated biochemistry analysers.
Instrument Specific Applications (ISA’s) are available for a wide range of biochemistry analysers.
For more information, visit: https://www.randox.com/lipoprotein-a or email: reagents@randox.com
The Complete Solution to Cardiac Risk Assessment
“CVDs are the number 1 cause of death globally: more people die annually from CVDs than from any other cause”. In 2015, roughly 17.7 million people died from CVD, representing 31% of all global deaths: 7.4 million were due to coronary heart disease and 6.7 million were due to stroke. (WHO, 2017)
Cardiac health and regular cardiovascular screening is important to enable risk factors to be detected in their earliest stages. There are a few factors which contribute to CVD. These include: smoking, unhealthy diet, excessive alcohol consumption, low physical activity levels. Whilst there are only a few factors contributing to CVD, these can be maintained by the patient through living a healthy lifestyle including: quitting smoking, consuming no more than the recommended allowance of alcohol, cutting out junk food, and exercising for 30 minutes a day, 3 – 5 days a week. In a perfect world, this would be easy and CVD would not be a global problem. However, due to busy lifestyles, cravings, reduced willpower, and convenience, not all individuals in today’s world will be able to avoid CVDs. Therefore, it is vitally important that individuals are tested for CVDs to detect them in the earliest stages to reduce damage, prevent further damage, or even death. Furthermore, many individuals suffer from inherited cardiac risk factors, which stresses the need for accurate testing of both traditional and novel cardiac risk biomarkers.
Randox offer the complete solution to cardiac risk assessment including: RX analysers, traditional and novel reagents, internal quality control (Acusera), and external quality control (RIQAS).
RX Series
Randox has developed the RX series range of clinical chemistry analysers for high-quality semi-automated and fully automated testing. Choose between the RX misano, RX monaco, RX daytona+, RX imola, and the RX modena depending on the throughput of your laboratory. The RX series offers a suitable analyser for your laboratory’s needs. For more information on the Randox RX series, please click here or email therxseries@randox.com
Reagents
As previously mentioned, early assessment of cardiac risk is vital. Randox offer a range of novel risk biomarkers for both very early and the genetic assessment of cardiac risk.
LDL cholesterol is often referred to as the ‘bad cholesterol’. High concentrations of LDL-cholesterol is considered to be the most important clinical predictor, of all single parameters, with respect to coronary atherosclerosis. However, sLDL is a smaller, more dense subfraction of LDL-cholesterol. sLDL particles more readily permeate the inner arterial wall and are more susceptible to oxidation. Individuals with a predominance of sLDL have a 3-fold increased risk of myocardial infarction. Measurement of sLDL allows the clinician to get a more comprehensive picture of lipid risk factors and tailor treatment accordingly.
Elevated levels of Lp(a) are considered to be both a casual risk factor and independent genetic marker of atherosclerotic disorders. The major challenge associated with Lp(a) measurement is the size variation of apo(a) within Lp(a). Dependent upon the size of apo(a) in the assay calibrator, many assays under or overestimate apo(a) size in the patient sample. Numerous commercially available products suffer apo(a) size related bias, resulting in an over estimation of Lp(a) in samples with large apo(a)molecules and an under estimation in samples with small apo(a) molecules. The antibody used in the Randox method detects the complete Lp(a) molecule providing accurate and consistent results. This was proven by the IFCC who developed a gold standard ELISA reference assay and compared 22 commercially available tests. The Randox Lp(a) method displayed the least (minimal) amount of apo(a) size related bias, proving it be a superior offering.
HDL3 Cholesterol is a smaller and more dense subfraction of the HDL particle. HDL is the scavenger of cholesterol within arterial walls and the levels of HDL3 is too low, the ability to remove this cholesterol is reduced. Therefore, it is widely accepted that there is an inverse correlation between HDL3 and CVD risk.
Instrument Specific Applications (ISA’s) are available for a wide range of biochemistry analysers. Contact us to enquire about your specific analyser.
For more information on Randox Reagents, please click here or email reagents@randox.com
Acusera – Internal Quality Control
The Acusera cardiac controls have been designed to cover a wide range of cardiac markers at clinical decision levels, eliminating the extra expense of an additional low level control. The controls are available in a both liquid ready-to-use and lyophilized formats making them ideal for all situations and manufactured from 100% human serum a matrix similar to that of the patient is guaranteed. For more information on the Randox Acusera internal quality control, please click here or email acusera@randox.com
RIQAS – External Quality Control
The RIQAS Liquid Cardiac EQA programme is designed to monitor the performance of up to 9clinically significant cardiac markers including: CK-MB mass, D-dimer, Digoxin, homocysteine, hsCRP, myoglobin, NT proBNP, troponin I, and troponin T. RIQAS is ISO/IEC 17043 accredited and allows the registration of up to five instruments at no extra cost. All samples are 100% human serum and provided in a liquid ready-to-use format for enhanced convenience. Submit your results bi-weekly and view reports online via RIQAS.Net. For more information on RIQAS, the world’s largest international EQA scheme, please click here or email acusera@randox.com
For further information, please contact the Randox PR team via email: randoxpr@randox.com or phone 028 9442 2413
Lipoprotein(a) Foundation commend celebrity personal trainer, Bob Harper, as he speaks out about the risk of Lp(a)
The Lipoprotein(a) Foundation have commended health and fitness expert Bob Harper for speaking out after recently suffering a heart attack. The celebrity personal trainer and host of the US television series ‘The Biggest Loser’, has revealed that high levels of Lp(a) were responsible for the heart attack he suffered at the age of 51 at the beginning of this year.1
Harper had been completing a normal workout at his gym when he suffered full cardiac arrest. Luckily, two doctors were in the vicinity who saved his life by performing CPR and using an Automated External Defibrillator (AED). In an interview following his heart attack, Harper has said,
“I’ve learned a lot about the fact genetics does play a part in this, it is so important to know your health… I’m a guy that lives a very healthy lifestyle, very regimented, I work out all the time, but there were things going on inside of my body that I needed to be more aware of and I strongly encourage anyone that’s listening right now to go to their doctor, get their cholesterol checked, see what’s going on on the inside”.
Scroll down to watch the interview in full.
What is Lp(a)?
Lp(a) is a particle which is produced in the liver and found in the blood which carries cholesterol, fats and proteins. Levels of Lp(a) in individuals are genetically determined, and are not affected by diet, exercise or lifestyle changes.2
So how does a seemingly fit and healthy person have a heart attack at the age of 51?
Lp(a) is currently the strongest inherited risk factor for heart attack and stroke, with one in five people globally inheriting high Lp(a).1 Levels of Lp(a) are not routinely tested in standard cardiovascular assessments, and despite the particle itself being an altered form of LDL cholesterol, standard cholesterol tests do not reveal inherited Lp(a) levels as it is independent from total cholesterol and LDL levels.3
High Lp(a) can also be unrelated to other common risks factors of cardiovascular diseases for example, smoking, diet, diabetes, high blood pressure and lack of exercise. This is why seemingly healthy individuals can have high Lp(a) in their genes and still be at high risk of cardiovascular diseases.
Why is Lp(a) not routinely measured if high levels pose such a risk?
The widespread use of Lp(a) as an independent risk factor for cardiovascular disease risk has, until recently, been hindered by the lack of internationally accepted standardisation and the fact that many commercial Lp(a) methods suffer from apo(a) size related bias, potentially leading to patient misclassification.
The size of the apo(a) protein is genetically determined and varies widely hence, levels of Lp(a) can vary up to 1000-fold between individuals.4 To find out more about the clinical significance of Lp(a), please refer to the section below entitled ‘For Health Professionals’.
What can you do if you have high Lp(a)?
Research has shown that lowering Lp(a) could significantly reduce the impact of cardiovascular diseases. A recent study published in the American Heart Association journal, Arteriosclerosis, Thrombosis and Vascular Biology, found that reducing high Lp(a) could potentially prevent up to 1 in 14 cases of myocardial infarction (heart attack) and 1 in 7 cases of aortic valve stenosis.5 Of those studied, nearly one third of heart attacks and half of all cases of aortic stenosis were attributed to high Lp(a).6 This study demonstrates the clinical significance of measuring Lp(a), making it a major independent genetic risk factor for cardiovascular diseases.
Why test Lp(a)?
Lp(a) will be tested as part of a lipid profile if: there is a strong family history of CVD, a patient has existing heart or vascular diseases, a patient has an inherited predisposition for high cholesterol or if a person has had a stroke or heart attack but has normal lipid levels.7
Dr Christie Ballantyne, Chief of Cardiology at Baylor College of Medicine, has said “the most important part of knowing your Lp(a) level is understanding your overall risk and finding the right lifestyle modifications or medications to target all the other traditional risk factors. Those risk factors become even more important to monitor when your Lp(a) levels are high”.8
For patients
If you are concerned that you may be at risk of having elevated levels of Lp(a) due to your family history, ask your doctor or medical provider to test lipoprotein (a), along with other lipid tests, to clinically evaluate your risk of developing cardiovascular diseases.
For health professionals
Click below for information regarding the challenges associated with the measurement of Lp(a) and the clinical significance it holds.
The widespread use of Lp(a) as an independent risk factor for cardiovascular disease risk has, until recently, been impeded by the lack of internationally accepted standardisation and the fact that many commercial Lp(a) methods suffer from apo(a) size related bias, potentially leading to patient misclassification. The size of the apo(a) protein is genetically determined and varies widely hence, levels of Lp(a) can vary up to 1000-fold between individuals.4
As a result, international criteria has been set to overcome these challenges. The International Federation of Clinical Chemistry (IFCC) Working Group on Lp(a) recommends that laboratories use assays which do not suffer from apo(a) size-related bias, in order to minimise the potential risk of misclassification of patients for coronary heart disease. The Lipoprotein(a) Foundation has referenced Marcovina and Albers (2016) as their recommendation for the best Lp(a) test.9 This recommendation is a result of the following conclusions:
- Robust assays based on the Denka method are available, which are reported in nanomoles per litre (nmol/L) and are traceable to WHO/IFCC reference material
- Five point calibrators with accuracy assigned target values will minimise the sensitivity to apo(a) size
A number of guidelines are in place for the testing of Lp(a) in patients.
-The European Guidelines for Management of Dyslipidaemia state that Lp(a) should be measured in individuals considered at high risk of CVD or with a strong family history of premature CVD.
-The European Atherosclerotic Society suggest that Lp(a) should be measured once in all subjects at intermediate or high risk of CVD/CHD who present with10 :
1. Premature CVD
2. Family hypercholesterolaemia
3. A family history of premature CVD and/or elevated Lp(a)
4. Recurrent CVD despite statin treatment
5. ≥3% 10-year risk of fatal CVD according to the European guidelines
6. ≥10% 10-year risk of fatal and/or non-fatal CHD according to the US guidelines
-EAS Consensus Panel states the evidence clearly supports Lp(a) as a priority for reducing cardiovascular risk, beyond that associated with LDL cholesterol. Clinicians should consider screening statin-treated patients with recurrent heart disease, in addition to those considered at moderate to high risk of heart disease.
- The Randox Lp(a) assay is one of the only methodologies on the market that detects the non-variable part of the Lp(a) molecule and therefore suffers minimal size related bias – providing more accurate and consistent results. The Randox Lp(a) kit is standardised to the WHO/ IFCC reference material SRM 2B and is closest in terms of agreement to the ELISA reference method.
- Five calibrators with accuracy-based assigned target values are provided – which accurately reflect the heterogeneity of isoforms present in the general population
- Measuring units available in nmol/L upon request
- Highly sensitive and specific – method for Lp(a) detection in serum and plasma
- Applications are available for a wide range of biochemistry analysers – which detail instrument-specific settings for the convenient use of Randox Lp(a) on a variety of systems
- Liquid ready-to-use reagents – for convenience and ease-of-use
For further information on Lp(a), click here or email: reagents@randox.com
1. Lipoprotein(a) Foundation, Lipoprotein(a) Foundation Thanks Bob Harper for Revealing High Lp(a) Levels Led to His Recent Heart Attack on The Dr Oz Show, 2017 Available from: http://www.businesswire.com/news/home/20170425006724/en/ [Accessed: 16 March 2017]
2. Lipoprotein Foundation, Understand Inherited Lipoprotein (a), Available from: https://goo.gl/bH5A8R [Accessed: 16 March 2017]
3. Kumar, V., Abbas, A. K. and Aster, J. C., Robbins and Cotran Pathologic Basic of Disease, (Philadelphia: Elsevier Saunders, 2015), p. 494 in Google books, https://goo.gl/VEnVX9 [Accessed 27th April 2017]
4. Kamstrup P.R., Tybjaerg-Hansen A., Steffensen R., Nordestgaard B.G. Genetically elevated lipoprotein (a) and increased risk of myocardial infarction. JAMA. Vol. 301, p. 2331-2339 (2009).
5. Afshar, M. Kamstrup, P.R., Williams, K., Snidermann, A. D., Nordestgaard, B.G., Thanassoulis, G., Estimating the Population Impact of Lp(a) Lowering on the Incidence of Myocardial Infarction and Aortic Stenosis – Brief Report., Ateriosclerosis, Thrombosis, and Vascular Biology, 2016;36:2421-2423, Available from: http://doi.org/10.1161/ATVBAHA.116.308271
6. The Lipoprotein(a) Foundation, Lipoprotein(a) Foundation Supports National Heart Valve Disease Month, Highlights Genetic Link between Lp(a) and Aortic Valve Disease, Business Wire. (2017), Available from: https://goo.gl/LhQFGj [Accessed: 16 March 2017]
7. Lab Tests Online, Lp(a), 2014, Available from: https://goo.gl/W2PWSN [Accessed: 16 March 2017]
8.Gutierrez, G., The heart attack risk factor you haven’t heard of, Baylor College of Medicine, 2017, Available from: https://goo.gl/9X4Xko [Accessed: 16 March 2017]
9. Marcovina, S.M. and Albers, J.J. Lipoprotein (a) measurements for clinical application. Lipid Res. Vol. 57, p. 526-37 (2016).
10. Nordestgaard, B. G., Chapman, M. J., Ray, K., Bore´n, J., Andreotti, F., Watts, G. F., Ginsberg, H., Amarenco, P., Catapano, A., Descamps, O. S., Fisher, E., Kovanen, P. T., Kuivenhoven, J. A., Lesnik, P., Masana, L., Reiner, Z., Taskinen, M. R., Tokgozoglu, L., and Tybjærg-Hansen, A., for the European Atherosclerosis Society Consensus Panel. Lipoprotein(a) as a cardiovascular risk factor: current status. European Heart Journal. Vol. 23, p. 2844-2853 (2010).
The scary facts about cholesterol!
Cholesterol is a fatty substance also known as a lipid. It is made by the liver but can also be found in some foods. It is essential to let the body function normally. You will be sad to hear that high levels can increase your risk of serious health conditions. There are two main types; high-density lipoproteins (HDL) and low-density lipoproteins (LDL). HDL is known as good cholesterol. It carries cholesterol back to the liver, where it is broken down. LDL on the other hand carries cholesterol to the cells however if there is a surplus it can build up in the artery walls increasing the chances of a heart attack or stroke occurring.
Here are some scary facts about cholesterol…
- You can’t live without it – Cholesterol has been in your body since the day you were born. It is a building block for all cells. Not only that but all of our cells and hormones need it to function properly…unfortunately you are very unlikely to find good cholesterol in your typical trick-or-treat offerings.
- Not all patients on cholesterol-lowering medication respond optimally to it – In the recent past, aspirin (a drug used to reduce levels) was prescribed for people who had a perceived risk of a heart attack. However aspirin does not always work; up to 30% of patients could have a below optimum response to the drug and therefore be at a considerably increased risk of a recurrent cardiovascular event. This is may also be referred to as “aspirin resistance”.
- One third of adults have high cholesterol – Testing is advised every 5 years to monitor your levels to see any changes. To get the most accurate results tests should be carried out one week apart, however most testing facilities won’t follow this.
- High levels could be down to genetics – Diet you can change, genes you can’t! If your family has a history of high cholesterol then you are likely to have it as well. It has been suggested that 75% of cholesterol is due to genetics and the remaining 25% is down to diet and lifestyle choices.
- Women’s levels will fluctuate over their lifespan – Did you know that ladies? During the average woman’s lifespan, cholesterol levels will rise and fall due to pregnancy and menopause. During pregnancy levels will rise in order to help the baby develop. After birth the mother’s levels should return to normal however after menopause a woman’s LDL levels will rise to that higher of a man’s.
However it is not all doom and gloom this Halloween! Randox are here to treat you to a vast range of specialised blood tests to allow the most accurate diagnosis of cholesterol levels, allowing you to gauge how many sweets you can sneak in this Halloween! We offer a large array of routine and niche tests. The most popular and widely tested are HDL, LDL, total cholesterol and triglycerides. Some further risk assessment cholesterol tests which are not routinely run include sLDL, HDL3, Lp(a). These cholesterol biomarkers are also affected by the usual risk factors such as age, weight, smoking, etc.; however they can also be a result of one’s genes. As mentioned before aspirin resistance is a big problem affecting up to 30% of all patients on aspirin therapy. However Randox offer the TxBCardio™ test which is a unique test to diagnose and assess the effectiveness of aspirin therapy.
From all of us here at Randox we wish you a safe and happy Halloween!
For health professionals
Randox Laboratories manufacture a wide range of routine and niche biochemistry reagents suitable for both research and clinical use. These include a wide variety of automated routine and niche cardiac tests and our new HDL3-C assay. Please contact reagents@randox.com for further information.
