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Antimicrobial Sensitivity Testing Using the Kirby-Bauer Disk Diffusion Method; Limited Utility in Ugandan Hospitals (lay summary)

This is a lay summary of the article published under the DOI: 10.31730/

Published onApr 19, 2023
Antimicrobial Sensitivity Testing Using the Kirby-Bauer Disk Diffusion Method; Limited Utility in Ugandan Hospitals (lay summary)

Better testing of antibiotics could help Ugandan hospitals improve treatments

Researchers say that Ugandan hospitals aren’t conducting enough tests for antibiotic resistance, and that using more efficient techniques could help them improve outcomes for hospital patients.

Antimicrobial resistance (AMR), or the ability of disease-causing microorganisms to survive treatment with deadly antibiotic drugs, is a growing cause of death around the world.  In developing countries, the problem is often worse, because hospitals have less resources available. This means they can’t always perform the tests that would tell doctors whether the antibiotics they’re prescribing are going to be effective.

In Uganda, there are only 8 hospitals that have the capability to perform these tests, and antimicrobial resistance is a growing problem in the country.

The researchers in this study wanted to know how often tests for antimicrobial resistance are performed in Ugandan hospitals, and whether hospitals are prescribing antibiotics with AMR in mind.

To find out, they looked at records from 3 Ugandan hospitals over a 2 month period in 2013. They were interested in the types of antibiotics being prescribed, how often doctors asked for tests of antimicrobial resistance, what type of tests were being done, and how long the tests took.

They focused on a commonly-used technique called antimicrobial sensitivity testing (AST), where disease-causing microorganisms are grown in the lab and exposed to different antibiotics. This test shows hospital staff which antibiotics will be most useful for treating a specific patient’s infection.

The researchers then analysed the data from the records to see if there was any relationship between the types of antibiotics being prescribed and the antibiotics tested during AST.

The researchers state that their statistical analysis showed a weak relationship between tests for antibiotic resistance and the antibiotics commonly prescribed. This means that the hospitals probably aren't using AST tests effectively to help them monitor antibiotic resistance and ensure they prescribe the best antibiotics to fight infections.

They also found that the rate of AST testing was very low. Doctors only requested an AST test for 4% of the patients before they prescribed antibiotics. In these cases, only half of the tests were actually performed, so there were only 13 records of AST tests in the 2 month period.

In addition, the tests took a long time to be completed, usually around 5 days, whereas patients commonly spent only 4 days in the hospital.

The researchers say that part of the problem may be that the hospitals don’t have enough staff trained to perform AST tests, and that they aren’t using the most efficient testing methods. They therefore suggest that Ugandan hospitals try using more efficient methods and employing more staff in the hospital laboratories to improve patient care and prevent antibiotic misuse.

They add that a limitation of their study is that they only used data from 3 hospitals, and this might mean their results don’t reflect the situation across Uganda. They recommend that future studies focus on comparing different methods of AST, and on finding other ways to test for antimicrobial resistance quickly and efficiently.

The study was conducted by researchers based in Uganda.


Background: Antimicrobial resistance (AMR) is a global health threat responsible for increased healthcare costs and mortality. The World Health Organization (WHO) global action plan on AMR recommends antimicrobial sensitivity testing (AST) and surveillance of antibiotic use to address this threat. We conducted a cross-sectional study to determine the utility of AST in three major referral hospitals in Uganda.

 Methods: We used abstraction checklists to collect data on AST requests, AST performed, AST turnaround time, and dispensed antibiotics, from in-patient files and laboratory and pharmacy records. Antibiotic data were summarized using proportions. The relationship between dispensed antibiotics and AST antibiotic-disks was analyzed using spearman’s rank correlation and simple linear regression.

 Results: Of the 607 in-patient files reviewed, AST was requested in 24 (4.0%), and done in 13 (2.1%). All three hospitals used the Kirby-Bauer disk diffusion method for AST, with a median turnaround time of 5 days (IQR 4-8). While the frequently used AST antibiotic-disks were cotrimoxazole (13.0%), ampicillin (11.7%), and ceftriaxone (10.5%), the most dispensed antibiotics were metronidazole (30.3%), amoxicillin (19.6%) and ceftriaxone (14.8%). There was a weak correlation (r=0.313, p=0.120) between dispensed antibiotics and AST antibiotic-disks, and AST performance was not associated with antibiotic consumption.

 Conclusion: We report an underutilization of AST, inconsistent with the hospital antibiotic consumption, and may be related to the use of the disk diffusion method. We recommend alternative faster and better coordination in the procurement of AST diagnostics in Ugandan hospitals.


This summary is a free resource intended to make African research and research that affects Africa, more accessible to non-expert global audiences. It was compiled by ScienceLink's team of professional African science communicators as part of the Masakhane MT: Decolonise Science project. ScienceLink has taken every precaution possible during the writing, editing, and fact-checking process to ensure that this summary is easy to read and understand, while accurately reporting on the facts presented in the original research paper. Note, however, that this summary has not been fact-checked or approved by the authors of the original research paper, so this summary should be used as a secondary resource. Therefore, before using, citing or republishing this summary, please verify the information presented with the original authors of the research paper, or email [email protected] for more information.

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