First, obtain a throat swab or other appropriate specimen for culture. Send it to a microbiology lab for identification and antibiotic susceptibility testing.
The lab uses techniques like Gram staining to initially identify the bacteria as Streptococcus. They then perform biochemical tests to determine the specific streptococcal species (e. g., Streptococcus pyogenes).
Antibiotic susceptibility testing, typically the disk diffusion method or broth microdilution, determines the minimum inhibitory concentration (MIC) of amoxicillin. An MIC above the established breakpoint indicates resistance.
Rapid diagnostic tests (RDTs) are available for some Streptococcus species, providing faster preliminary results but not always providing antibiotic susceptibility data. These results should still be confirmed through culture and susceptibility testing.
If amoxicillin resistance is suspected or confirmed, alternative antibiotics like clindamycin, erythromycin, or ceftriaxone are considered, guided by local antibiograms. Always refer to current guidelines for appropriate treatment choices.
Proper specimen collection, timely lab processing, and accurate interpretation of results are key to successful diagnosis and management. Close monitoring of the patient’s response to treatment is crucial.
