Everyday health / Evidence explained
Antibiotic resistance and the laboratory’s role
How resistance develops, what WHO surveillance shows, and how culture and susceptibility testing support clinical decisions.
Key takeaway
Resistance is a property of microbes. Appropriate samples, bacterial identification and careful interpretation of susceptibility results support responsible antibiotic use.
What becomes resistant?
Antibiotic resistance describes a change in bacteria: they can survive a medicine that previously stopped them multiplying. The human body does not become “resistant”. Bacteria can develop protective mechanisms and exchange genetic material that helps resistance spread. Understanding this distinction makes laboratory reports easier to interpret.
The problem also involves how medicines are used and how infections are prevented. WHO addresses it through a “One Health” approach connecting human health, animals and the environment. The response therefore includes hygiene, access to diagnostics and appropriate antimicrobial use across several sectors of society.
What the 2025 report showed
On 13 October 2025, WHO reported that around one in six laboratory-confirmed bacterial infections in the groups studied globally for 2023 was resistant to antibiotic treatments. This figure does not mean that one in six people has a resistant infection; the population being measured matters.
The analysis draws on over 23 million confirmed cases, including bloodstream, urinary tract and gastrointestinal infections and urogenital gonorrhoea. These data do not represent every infection or every country equally. They cannot be used as a measurement of prevalence in Albania or a prediction for an individual patient.
From the sample to culture and susceptibility testing
Culture involves growing bacteria from a sample chosen according to the suspected infection site, such as urine or blood. It helps identify the organism responsible. Growth takes time, and slower-growing bacteria may extend the wait. There is no single turnaround time that applies to every culture.
Susceptibility testing, sometimes called an antibiogram, examines how the microbe responds to particular antibiotics. Culture and susceptibility testing answer related but different questions: “Which microbe was found?” and “Which antibiotics is it susceptible to?”. The result helps the clinician assess options for that particular infection.
Quality begins before analysis
A contaminated sample can produce a misleading answer. With blood cultures, ordinary skin microbes can enter during collection and create the impression of a bloodstream infection. CDC links reducing contamination with avoiding unnecessary antibiotics and longer hospital stays. Collection technique therefore affects the usefulness of the result.
IDSA/ASM guidance emphasizes choosing the specimen, quantity and transport conditions appropriate to each clinical question. This explains why laboratory collection instructions deserve careful attention. A suitable container and a sample from the correct site are part of the test, just as much as the later measurement.
Reading the letters on a susceptibility report
In the EUCAST system, S means susceptible with a standard dosing regimen; I means susceptible with increased antibiotic exposure; R means resistant. Category I is not equivalent to R. Exposure also depends on administration and the infection site, so interpretation belongs with a healthcare professional.
Interpretive thresholds are updated. At the date of this article, the EUCAST table for 2026 is version 16.1. This is a reason to read a report with its relevant standard, rather than mechanically comparing every letter with an older test. A laboratory result is not an instruction to change your own dose.
Value for the patient and the community
Laboratories also contribute to resistance surveillance. WHO describes how reference laboratories support standardization, quality assurance and confirmation of new resistance mechanisms. Reliable information helps detect changes over time and organize control measures beyond an individual result. Consistent methods make the accumulated information more useful.
For patients, the practical steps are straightforward: take antibiotics as prescribed, do not share them and do not save leftovers for a future illness. Antibiotics do not treat viral illnesses such as colds and flu. The useful question is what information is needed for today’s decision, together with your clinician.
Sources
- About Antimicrobial Resistance ↗CDC · Accessed 15 September 2026
- Antimicrobial resistance ↗World Health Organization · Accessed 15 September 2026
- WHO warns of widespread resistance to common antibiotics worldwide · 13 October 2025 ↗World Health Organization · Accessed 15 September 2026
- Global antibiotic resistance surveillance report 2025 ↗World Health Organization · Accessed 15 September 2026
- Bacteria Culture Test ↗MedlinePlus · National Library of Medicine · Accessed 15 September 2026
- Antibiotic Sensitivity Test ↗MedlinePlus · National Library of Medicine · Accessed 15 September 2026
- Prevent Adult Blood Culture Contamination · 31 March 2026 ↗CDC · Accessed 15 September 2026
- IDSA/ASM 2024 Guide to Utilization of the Microbiology Laboratory for Diagnosis of Infectious Diseases ↗IDSA · American Society for Microbiology · Accessed 15 September 2026
- Definitions of S, I and R ↗EUCAST · Accessed 15 September 2026
- Clinical Breakpoint Tables · version 16.1, 2026 ↗EUCAST · Accessed 15 September 2026
- GLASS guidance for national reference laboratories ↗World Health Organization · Accessed 15 September 2026
- Healthy Habits: Antibiotic Do’s and Don’ts ↗CDC · Accessed 15 September 2026
An editorial explanation referring to the listed sources. General information; individual interpretation and treatment require clinical assessment.
Updated 15 September 2026. How we prepare our content