This is a Phase 1, randomized, double-blind, single-center, placebo-controlled, sequential-cohort study in at least 60 healthy adult male and female subjects. Subjects in Cohorts 1 through 5 will be randomly assigned in an 8:2 allocation to receive active or placebo treatments. Subjects in Cohort 6 will be randomly assigned in a 1:1 allocation to receive an IV dose of nafithromycin and a single oral dose of nafithromycin in each crossover period. Subjects in each of Cohorts 1, 2, and 3 will receive a single dose of 100, 200, or 400 mg, respectively, of nafithromycin or matching placebo on Day 1.

Inclusion Criteria:

• Male or female subject between 18 and 55 years of age, both inclusive,
• creatinine clearance ≥80 mL/minute (Cockcroft-Gault method).

Exclusion Criteria:

1. Clinically relevant pathology or any other systemic disorder/major surgeries that in the opinion of the investigator would confound the subject's participation and follow-up in the clinical study.
2. Drug or food allergy.