Can heterogeneous resistance, indicated by the presence of small discrete colonies inside the zone of inhibition, affect the zone diameter in disk diffusion susceptibility testing?
Yes, heterogeneous resistance can indeed affect the zone diameter in disk diffusion susceptibility testing. It is essential to consider additional testing methods, such as broth microdilution or gradient diffusion assays, which provide more detailed information on the minimum inhibitory concentration (MIC) of the antibiotic against the bacterial isolate. These methods can help detect heterogeneous resistance and provide a more accurate assessment of antimicrobial susceptibility.
Yes, heterogeneous resistance can indeed affect the zone diameter in disk diffusion susceptibility testing.
In disk diffusion susceptibility testing, antimicrobial susceptibility of bacteria is assessed by measuring the zone of inhibition around an antimicrobial disk on a culture plate. The diameter of this zone is indicative of the susceptibility of the bacteria to the antimicrobial agent.Heterogeneous resistance refers to the presence of subpopulations of bacteria within a culture that exhibit varying degrees of susceptibility to the antimicrobial agent being tested. This means that while the majority of the bacteria may be susceptible to the antimicrobial, there could be small subpopulations that are resistant.When performing disk diffusion testing, if there are subpopulations of resistant bacteria within the culture, the zone of inhibition may appear larger than expected. This is because the susceptible bacteria surrounding the resistant subpopulations are still inhibited by the antimicrobial, leading to a wider zone of inhibition. As a result, the zone diameter may not accurately reflect the true susceptibility of the bacterial population as a whole.
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