# The only antibiotic in periodontal therapy to which all strains of A. actinomycetemcomitans are susceptible:
A. Azithromycin
B. Ciprofloxacin
C. Cvefidipine
D. Metronidazole
The correct answer is B. Ciprofloxacin.
Ciprofloxacin
Pharmacology: Ciprofloxacin is a quinolone that is active against gram-negative rods, including all facultative and some anaerobic putative periodontal pathogens.
Clinical Use: Because it demonstrates a minimal effect on Streptococcus species, which are associated with periodontal health, ciprofloxacin therapy may facilitate the establishment of a microflora that is associated with periodontal health. At present, ciprofloxacin is the only antibiotic in periodontal therapy to which all strains of A. actinomycetemcomitans are susceptible. It has also been used in combination with metronidazole.
Reference: Carranza's Clinical Periodontology, 12th Edition, Page no: 519