Which is a disadvantage of automated susceptibility testing systems?

• A. Not all MICs can be tested, especially newer antibiotics
• B. Always accurate for all MICs
• C. Cannot test MICs at all
• D. They replace all manual methods

Answer: (A)

Automated susceptibility testing systems are designed to be fast and standardized by using pre-set panels of antibiotics and software rules to estimate MICs. A key disadvantage is that the panels are finite and may not include every antimicrobial, particularly newly approved drugs. As new agents enter use, adding them to automated systems requires validation, updates, and sometimes new hardware or licenses, so you may not be able to test all MICs with the system. In practice, labs often need to supplement with manual broth microdilution or send tests to reference methods for drugs not on the panel or for unusual resistance patterns.

The other statements aren’t accurate: these systems aren’t perfect for all MICs (inaccuracies can occur depending on drug, organism, or conditions); they do test MICs for many drugs; and they don’t completely replace manual methods, which are still used for drugs not on the panel or for confirmation.