Prevalence and antimicrobial susceptibility of Enterobacteriaceae, Pseudomonadaceae and Acinetobacter in human periodontitis.

This study examined the occurrence of non-oral gram-negative facultatively anaerobic rods in advanced adult periodontitis. Speciation and in vitro antimicrobial susceptibility testing was performed using the MicroScan micromethod system. A total of 42 taxa of Enterobacteriaceae, Pseudomonadaceae and Acinetobacter were isolated from 427 of 3,050 (14.0%) patients. In 159 (5.2%) patients, these organisms comprised more than 5% of the cultivable subgingival microflora. Enterobacter cloacae, Klebsiella pneumoniae, Pseudomonas aeruginosa, Klebsiella oxytoca and Enterobacter agglomerans accounted for more than 50% of all strains isolated. Virtually all study strains demonstrated high in vitro susceptibility to ciprofloxacin, but exhibited variable susceptibility patterns to 18 other antimicrobial agents tested. In 3 "refractory" periodontitis patients heavily infected with enteric rods, systemic ciprofloxacin therapy (500 mg BiD for 10 days) led to resolution of the subgingival infections and improved clinical periodontal status. The present findings indicate that 5% of severe periodontitis lesions may harbor high levels of non-oral, gram-negative, facultatively anaerobic rods. Systemic ciprofloxacin appears to be capable of eradicating these potential pathogens from deep periodontal pockets.