A narrow-spectrum antibiotic is an antibiotic that is only able to kill or inhibit limited species of bacteria.
[1] Examples of narrow-spectrum antibiotics include fidaxomicin and sarecycline.
Often, the exact species of bacteria causing the illness is unknown, in which case narrow-spectrum antibiotics can't be used, and broad-spectrum antibiotics are used instead.
To know the exact species of bacteria causing the illness, clinical specimens need to be taken for antimicrobial susceptibility testing in a clinical microbiology laboratory.
[citation needed] This systemic antibiotic-related article is a stub.