Antibiogram
What is analysed?
An antibiogram is a laboratory test that analyses the effectiveness of various antibiotics against bacteria isolated from a patient's sample. It helps determine which antibiotics are most suitable for treating a particular infection.
What does the result mean?
The results of an antibiogram indicate the sensitivity or resistance of the bacteria to specific antibiotics. This information guides healthcare providers in choosing the most appropriate antibiotic therapy for the patient.
Why conduct the analysis?
Antibiograms are crucial in ensuring effective treatment of bacterial infections. By identifying which antibiotics are likely to be effective, healthcare providers can tailor treatment plans to individual patients, minimise the risk of antibiotic resistance, and improve patient outcomes.
When to perform the analysis?
An antibiogram is typically performed when a bacterial infection is suspected or confirmed. It is especially important in cases where initial antibiotic therapy fails or when dealing with recurrent infections.
What sample is required?
Samples for antibiogram analysis vary depending on the suspected site of infection. Common samples include blood, urine, sputum, wound swabs, and tissue samples.
Is any prior preparation necessary?
Prior to collecting samples for an antibiogram, it's important to follow proper collection techniques to ensure accuracy. For example, sterile techniques should be used to collect samples, and the samples should be promptly transported to the laboratory for analysis.
How is it used?
Once the antibiogram results are available, healthcare providers can use them to select the most appropriate antibiotic therapy for the patient. The choice of antibiotic is based on the bacteria's susceptibility profile and the patient's clinical condition.
What are the normal values?
In an antibiogram, the normal values represent the antibiotics to which the isolated bacteria are sensitive. These antibiotics are likely to be effective in treating the infection.
Table of antibiotic sensitivity
Antibiotic
Sensitive (%)
Resistant (%)
Intermediate (%)
Amoxicillin
65
35
0
Ciprofloxacin
80
20
0
Penicillin
70
30
0
Erythromycin
75
20
5
Trimethoprim-
Sulfamethoxazole
60
35
5
(Note: These values are for illustrative purposes and may vary depending on the specific bacterial strain and laboratory protocols.)
What do altered values indicate?
Altered values in an antibiogram indicate resistance of the bacteria to certain antibiotics. This means that those antibiotics are unlikely to be effective in treating the infection, and alternative antibiotic therapy may be necessary.