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:
- Infective endocarditis
- Skin and soft tissue infections
- Septic arthritis
- Prosthetic device infections
- Pulmonary infections
- Toxic shock syndrome
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.
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.
- Methicillin-resistant Staphylococcus aureus
- Methicillin-sensitive Staphylococcus aureus
Specific Gene Targets:
- SCCmec/orfX junction
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.
- 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
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
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.
How can Randox help?
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!
THE 2023 RANDOX GRAND NATIONAL TROPHY IS REVEALED
Sunday 19th March
The Randox Grand National Trophy is one of the most iconic and prestigious sporting trophies in the world of horseracing. From the start of the Randox sponsorship of the Grand National in 2017, Randox CEO Dr Peter FitzGerald proposed a unique trophy would be designed and produced each year. The winning owner receives the full size the trophy, with the winning trainer, jockey and groom all receiving a miniature version.
Each trophy is uniquely Randox and has a story to tell. The design of the trophy has evolved over the years and the 2023 trophy, which is revealed today, has a special significance as it incorporates several key elements that represent the company’s values and achievements – alongside a nod to a very special racehorse.
At the top of the trophy there is a beautifully crafted horse mid-jump, symbolising the 30 fences that the winner will navigate during the four-mile, two-and-a-half-furlong contest on Saturday 15th April. The horse is shown making its way over a horseshoe instead of a fence, representing protection and good luck.
In the centre of the trophy, a gold blood drop symbolises Randox’s diagnostic testing. This leads up to the DNA double helix, representing the company’s genomic testing capabilities. Randox offers seven different types of genetic testing, empowering people to find out more about their future health.
The base of the trophy features a molecular pattern, representing Randox’s molecular testing capabilities. The “o” in Randox is embellished with red enamel, symbolising accuracy and precision, which are integral to the Randox brand. The red enamel is also representative of a blood drop, used in much of Randox’s diagnostic testing.
Etched along the bottom of the trophy, is “Celebrating the 50th anniversary of Red Rum winning his first Grand National race” paying tribute to the legendary Red Rum’s first of his record three Grand National triumphs in 1972. The quartet of silver strands that connect the top and bottom of the trophy represent Randox’s support of racing and sponsorship of the Grand National.
Elizabeth Moran of Randox, who designed the trophy, said: “It was a wonderfully creative challenge to design this year’s trophy, reflecting both this national, iconic sporting event and Randox’s innovation within healthcare, and I think we got it just right.”
Silversmith Cara Murphy, who produced the trophy added: “I am delighted with what we have achieved. This is a highly intricate trophy and was challenging to produce – the end result is a trophy to grace the podium and recognise the achievement of winning the world’s greatest steeplechase.”
The 2023 Randox Grand National Trophy is a beautiful and intricate work of art that embodies the company’s commitment to innovation, accuracy, and precision in the field of diagnostic testing. The horse, the horseshoe, and the nod to Red Rum all come together to create a stunning and symbolic celebration of horseracing.
During the Randox Grand National Festival (Thursday 13th April – Friday 15th April inclusive), the trophy as well as trophies from previous Randox Grand Nationals, can be viewed in trophy marquee next to the Red Rum Garden at Aintree Racecourse.
World Kidney Day 2023
“Kidney health for all – Preparing for the unexpected, supporting the vulnerable”
Thursday 09th March
Chronic Kidney Disease (CKD) is considered a leading cause of global mortality with an overall global prevalence rate of around 13%1. This figure rises to 15% in the US2 and the statistics show that these rates are likely to continue this upward trend3. CKD is defined as damage to the kidneys which affects its ability to correctly filter bodily fluids which ultimately results in renal replacement therapy in the form of dialysis or transplantation4. This sustained or chronic damage of the kidney encourages kidney fibrosis and loss of structure. The early stages of CKD are generally asymptomatic with symptoms beginning to manifest in stages 4 and 5. These symptoms include nausea & vomiting, fatigue & weakness, oliguria, chest pain, hypertension, to name a few4.
World Kidney Day is an annual, global campaign spearheaded by the International Society of Nephrology (ISN) and the International Federation of Kidney Foundations – World Kidney Alliance (IFKF – WKA) which intends to raise awareness of how critical our kidneys are and to limit the prevalence and impact of kidney disease5. This year’s focus is “Kidney health for all – preparing for the unexpected, supporting the vulnerable.”
It is no surprise that patients suffering from noncommunicable diseases (NCDs) such as CKD were subject to worse prognosis during the COVID-19 pandemic6 due to prioritising of ongoing complex care over acute patient care7. But a pandemic is only one circumstance, albeit a major one, which can affect the ability of hospitals and laboratories to uphold their normal testing capacity. For example, natural disasters can make it impossible for people to reach facilities for testing or treatment7. Similar situations could arise at a more local level such as road closures, power outages or public transport strikes which have the potential to delay diagnosis or treatment.
To this end, laboratories should look to introduce novel and effective methods for testing under adverse conditions. Rapid testing will be imperative to help achieve these goals and promote fast test turnaround times and accurate diagnosis. The Randox CKD Arrays, in conjunction with the Randox Evidence Investigator, allow for simultaneous and quantitative detection of multiple serum biomarkers of kidney damage-related analytes allowing diagnosis at a much earlier stage than traditional creatinine tests.
Utilising patented Biochip Technology, the Randox CKD arrays could improve patient risk stratification whilst monitoring the effectiveness of treatment. Diagnosis of CKD at early stages will allow earlier intervention for the treatment of kidney disease, and the prevention of further kidney damage. The utility of this test cannot be overstated. In adverse circumstances, the Randox Evidence Investigator could permit diagnosis of CKD and determination of CKD severity at the site of the patient, helping prepare for the unexpected and support the vulnerable.
More information of CKD and other kidney related conditions can be found at: Homepage – World Kidney Day
Lv JC, Zhang LX. Prevalence and Disease Burden of Chronic Kidney Disease. Advances in Experimental Medicine and Biology. 2019;1165:3-15. doi:https://doi.org/10.1007/978-981-13-8871-2_1
Centers for Disease Control and Prevention. Chronic Kidney Disease in the United States, 2021. US Department of Health and Human Services; 2021. https://www.cdc.gov/kidneydisease/pdf/Chronic-Kidney-Disease-in-the-US-2021-h.pdf
Kovesdy CP. Epidemiology of chronic kidney disease: an update 2022. Kidney International Supplements. 2022;12(1):7-11. doi:https://doi.org/10.1016/j.kisu.2021.11.003
Vaidya SR, Aeddula NR. Chronic renal failure. Nih.gov. Published 2019. https://www.ncbi.nlm.nih.gov/books/NBK535404/
International Society of Nephrology. Homepage. World Kidney Day. Published 2023. https://www.worldkidneyday.org/
Nikoloski Z, Alqunaibet AM, Alfawaz RA, et al. Covid-19 and non-communicable diseases: evidence from a systematic literature review. BMC Public Health. 2021;21(1). doi:https://doi.org/10.1186/s12889-021-11116-w
Hsiao LL, Shah KM, Liew A, et al. Kidney health for all: preparedness for the unexpected in supporting the vulnerable. Kidney International. 2023;103(3):436-443. doi:https://doi.org/10.1016/j.kint.2022.12.013
For more information, please contact Market@randox.com