A recent review of research looked at whether a genetic test could predict if Streptococcus pneumoniae bacteria are resistant to beta-lactam antibiotics, a common class that includes penicillin. The test examines three genes (PBP1a, PBP2b, and PBP2x) to estimate the minimum inhibitory concentration (MIC), which is the lowest drug dose needed to stop bacterial growth.
The review found that this genome-based method had high overall agreement with standard lab tests that grow the bacteria in the presence of the drug. This suggests the genetic approach could be a useful tool for tracking resistance patterns in populations.
However, the review is based on a limited number of studies, and the test may not work well for rare resistance profiles or when bacteria have swapped genes with related species. Also, the predicted MIC cannot directly guide treatment decisions without considering the specific antibiotic, infection site, and dosing.
For now, this genetic method is best suited for surveillance, not for making individual treatment choices. More research is needed before it can be used in routine clinical care.