Clonal diversity of Cutibacterium acnes (formerly Propionibacterium acnes) in prosthetic joint infections.

Prosthetic joint infections (PJIs) are rare but feared complications following joint replacement surgery. Cutibacterium acnes is a skin commensal that is best known for its role in acne vulgaris but can also cause invasive infections such as PJIs. Some phylotypes might be associated with specific diseases, and recently, a plasmid was detected that might harbour important virulence genes. In this study, we characterized C. acnes isolates from 63 patients with PJIs (n = 140 isolates) and from the skin of 56 healthy individuals (n = 56 isolates), using molecular methods to determine the phylotype and investigate the presence of the plasmid. Single-locus sequence typing and a polymerase chain reaction designed to detect the plasmid were performed on all 196 isolates. No statistically significant differences in sequence types were seen between the two study groups indicating that the C. acnes that causes PJIs originates from the patients own normal skin microbiota. Of the 27 patients with multiple tissue samples, 19 displayed the same sequence types among all their samples. Single-locus sequence typing identified different genotypes among consecutive C. acnes isolates from four patients with recurrent infections. The plasmid was found among 17 isolates distributed in both groups, indicating that it might not be a marker for virulence regarding PJIs. Patients presenting multiple sequence types in tissue samples may represent contamination or a true polyclonal infection due to C. acnes.

Empiric treatment of acute diarrheal disease with norfloxacin. A randomized, placebo-controlled study. Swedish Study Group.

OBJECTIVE: To evaluate the clinical and microbiologic efficacy and safety of norfloxacin for acute diarrhea. DESIGN: Double-blind, placebo-controlled, randomized clinical multicenter trial. SETTING: Six departments of infectious disease. PARTICIPANTS: Patients 12 years of age or older with a history of acute diarrhea lasting 5 or fewer days. Eighty-five percent of patients (511/598) were evaluable for efficacy. Of these evaluable patients, 70% had traveled abroad within the previous 6 weeks. INTERVENTIONS: Patients received either norfloxacin, 400 mg, or placebo twice daily for 5 days. MEASUREMENTS: Enteric pathogens were isolated in 51% of the evaluable patients: Campylobacter species in 29%, Salmonella species in 16%, Shigella species in 3.5%, and other pathogens in 2.6%. RESULTS: Norfloxacin had a favorable overall effect compared with placebo (cure rate, 63% compared with 51%; P = 0.003). There were statistically favorable effects in culture-positive patients, patients with salmonellosis, and severely ill patients but not in culture-negative patients or patients with campylobacteriosis or shigellosis. A significant difference was noted between norfloxacin and placebo in median time to cure among all evaluable patients (3 compared with 4 days, P = 0.02) and in patients with campylobacteriosis (3 compared with 5 days, P = 0.05) but not in patients. Culture-positive, but not culture-negative patients, in the norfloxacin group had significantly fewer loose stools per day compared with patients in the placebo group from day 2 onward (P less than or equal to 0.01). Norfloxacin was significantly less effective than placebo in eliminating Salmonella species on days 12 to 17 (18% compared with 49%, P = 0.006), whereas the opposite was true for Campylobacter species (70% compared with 50%, P = 0.03). In six of nine patients tested, norfloxacin-resistant Campylobacter species (MIC, greater than or equal to 32 micrograms/mL) appeared after norfloxacin treatment. CONCLUSION: Empiric treatment reduced the intensity and, to some extent, the duration of symptoms of acute diarrhea. The effect was restricted to patients who had bacterial enteropathogens or who were severely ill. The clinical usefulness of this treatment is limited by the fact that norfloxacin seems to delay the elimination of salmonella and to induce resistance in campylobacter.