When we talk about antimicrobial resistance (AMR), the conversation often focuses on antibiotics: how we use them, how resistance develops, and the urgent need for new treatments and diagnostics. But another important question is whether we are identifying antimicrobial-resistant organisms early enough for that information to make a difference, both to the patient’s care and to preventing transmission to others.
Screening can provide healthcare teams with important information before infection develops. When used appropriately, identifying colonisation can inform clinical decisions and infection prevention and control (IPC) measures, while giving patients a better understanding of information that may be relevant to their future healthcare.
Colonisation is not the same as having an infection
A person may carry an organism such as methicillin-resistant Staphylococcus aureus (MRSA), carbapenem-resistant Enterobacterales (CPE) or vancomycin-resistant enterococci (VRE) without symptoms. This is known as colonisation.
Being colonised does not mean someone is ill or will necessarily develop an infection. However, this information may become important if they are admitted to hospital, undergo surgery, require intensive care, or receive treatment that weakens the immune system.
Knowing about colonisation may therefore help healthcare teams understand a patient’s risk, plan care appropriately and consider measures aimed at limiting transmission to other vulnerable patients.
Not every patient needs every screening test
Screening is most valuable when there is a clear reason for doing it and when the result could influence care. Healthcare professionals may consider previous resistant infections or colonisation, recent hospital admissions, transfer between healthcare facilities, or admission to higher-risk areas such as intensive care, oncology, haematology or transplant units.
The appropriate approach will differ according to the organism suspected, healthcare setting, patient population and local epidemiology. Importantly, patients should understand why they are being screened, what is being tested for and what will happen when the result becomes available.
A result is valuable when we can act on it
A screening result is valuable when it leads to an appropriate action for the patient or the healthcare team.
Rapid molecular tests can, in some circumstances, identify resistant organisms much sooner than traditional laboratory methods. Earlier information may allow healthcare teams to introduce appropriate IPC measures sooner.
If a patient later develops an infection, knowledge of previous colonisation or resistant organisms may also provide useful information when clinicians consider possible causes and treatment options.
However, speed alone is not enough. A rapid result needs to reach the right healthcare professional, be correctly interpreted and lead to an appropriate response. Laboratories, clinicians, nurses, IPC teams and antimicrobial stewardship programmes therefore need clear pathways for communicating and acting on results.
Screening and responsible antibiotic use go together
Patients understandably want effective treatment when they develop a serious infection. At the same time, unnecessary exposure to broad-spectrum antibiotics can have consequences for individual patients and contribute to AMR.
Knowledge of previous resistant organisms can provide useful information when doctors need to make treatment decisions. Screening should never replace appropriate clinical assessment or diagnostic testing of an active infection, and colonisation does not necessarily predict the cause of a future infection. It can, however, provide additional information that may help clinicians make better-informed decisions.
Screening, diagnostics, IPC and antimicrobial stewardship should therefore be viewed as connected components of an informed approach to managing AMR.
A positive result can be frightening
Being told, “You are carrying a resistant organism,” can cause anxiety. A patient may hear the word resistant and assume they have a dangerous infection that cannot be treated.
Communication therefore matters. Patients should be told clearly whether the result represents colonisation or infection, what organism has been detected, whether treatment is required, why additional precautions may be necessary and what the result could mean for their future healthcare and their family.
Isolation or additional infection-control measures can also make patients feel stigmatised. These measures should be explained sensitively, including why they are being used and what they mean for the patient.
Patients should be partners in managing AMR
Patients should receive clear information about their results and be supported to understand how they may affect their current and future care.
Healthcare systems also have a responsibility to ensure that important microbiological information follows patients through their healthcare journey, so that relevant results are available when future clinical decisions are made, rather than relying entirely on patients to remember complex microbiological information.
As AMR increases, the question should therefore not simply be “Who should we screen?” We should also ask: Will the result matter to this patient? How quickly do we need it? What will we do differently if it is positive? And how will we explain it to the patient?
Tackling AMR is not only about finding the next antibiotic. It is also about identifying risk earlier, communicating information clearly and ensuring that screening results lead to appropriate, patient-centred action.
Additional Reading & Resources
Huang SS et al. Decolonization to reduce post-discharge infection risk among MRSA carriers. New England Journal of Medicine. 2019;14,380(7):638-650.
Screening identifies colonisation, the subsequent intervention (not screening itself) can reduce infection. In this randomised controlled trial, decolonisation of known methicillin-resistant Staphylococcus aureus (MRSA) carriers reduced MRSA infection risk by about 30%.
Huang SS et al. Targeted versus universal decolonization to prevent ICU infection. New England Journal of Medicine. 2013;13,368(24):2255-2265.
“Not every patient needs every screening test” It directly compared screening/isolation, targeted decolonisation after screening, and universal decolonisation in intensive care units. Importantly, it demonstrated that screening is one possible strategy, not automatically the best approach in every setting.
Liu X et al. Prediction models for diagnosis and prognosis of colonization or infection of multidrug-resistant organisms in adults. Clinical Microbiology and Infection. 2024; 30(11):1364-1373.
Strong systematic review supporting risk-based identification. Across 108 studies, common predictors included previous antibiotic exposure, hospitalisation, age and invasive procedures. It also cautions that existing prediction models have substantial limitations, useful for avoiding overstatement about risk-based screening.
Merrick B et al. The role of the gut microbiome in multidrug-resistant organism colonization and infection. Clinical Microbiology and Infection. 2026;32(7):1060-1066.
Colonisation is not infection but can precede infection and contribute to onward transmission. Particularly applicable to gastrointestinal carriage of multidrug-resistant organisms.
Morency-Potvin P et al. Antimicrobial stewardship: How the microbiology laboratory can right the ship. Clinical Microbiology Reviews. 2017;14;30(1):381-407.
Laboratory results must connect with clinical microbiology, rapid diagnostics, surveillance and antimicrobial stewardship, rather than testing existing in isolation.
Messacar K et al. Implementation of rapid molecular infectious disease diagnostics: the role of diagnostic and antimicrobial stewardship. Journal of Clinical Microbiology. 2017;55(3):715-723.
“A result is valuable when we can act on it” The article argues that rapid molecular technology needs diagnostic and antimicrobial stewardship for effective clinical implementation.
World Health Organization (WHO): Strengthening clinical diagnostic stewardship in the Western Pacific Region: a practical manual.
“Clinical diagnostic stewardship – taking the right test in the right way at the right time and using the results correctly, saves lives. Fighting antimicrobial resistance (AMR) needs an integrated approach to optimizing diagnosis, treatment, prevention and control of bacterial infections.”
This blog is a The AMR Narrative Project supported by Cepheid.
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Dr Stefan Opperman
BSc (Molecular biology), BScHons (Microbiology), MBChB (Stellenbosch), FCPath SA (Microbiology), MMed Path (Microbiology), Dip HIV Man(SA)
Dr Stefan Opperman is a clinical microbiology pathologist at the National Health Laboratory Service (NHLS), Green Point Tuberculosis Laboratory, Cape Town, South Africa. He completed his specialist training in the Division of Medical Microbiology, Department of Pathology, at the University of Cape Town and Groote Schuur Hospital, where he remains actively involved in undergraduate and postgraduate teaching as an honorary lecturer. He is also affiliated with the Division of Molecular Biology and Human Genetics, Department of Biomedical Sciences, Stellenbosch University, where he is completing a PhD investigating clinically important non-tuberculous mycobacteria. He has an additional background in molecular biology, with particular interests in tuberculosis and non-tuberculous mycobacteria, infectious disease outbreaks, and antimicrobial and diagnostic stewardship. Dr Opperman serves on the Western Cape Provincial Antimicrobial Stewardship Committee and actively participates in antimicrobial stewardship ward rounds at peripheral hospitals. He has a particular passion for extending antimicrobial stewardship beyond tertiary healthcare settings into the community, with a focus on practical stewardship, education, and supporting appropriate antimicrobial use at primary healthcare level.
Vanessa Carter
Vanessa became an AMR patient advocate in 2013 after surviving a serious car accident and 10-year facial reconstruction that caused a highly-resistant MRSA infection on her face.
She has won awards for her advocacy including a Woman of Stature (WOS) Woman of the Year Award, FINDdx Voices for Diagnostics Award, and Antibiotic Guardian Award in the Community Communications category organised by the UK Health Security Agency (UKHSA).
She has also advocated the importance of patient and public involvement and engagement. Originally from South Africa, she now resides in the UK and has worked globally. Vanessa was also the founder and currently serves as an Executive Director for The AMR Narrative.
