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Minimum bactericidal concentrations of Propionibacterium acnes isolates from cases of chronic endophthalmitis
G S Hall1, K Pratt-Rippin, D M Meisler
1Department of Microbiology, Cleveland Clinic, OH 44195-5140, USA.
Abstract:
Six isolates of Propionibacterium acnes recovered from cases of chronic infectious endophthalmitis following extracapsular cataract extraction were tested for antibiotic susceptibility. All isolates were susceptible to penicillin, cefazolin, and vancomycin with a macrobroth dilution method. Minimum bactericidal concentrations testing at 72 h revealed that six of six isolates were killed by < or = 1.0 micrograms of vancomycin/ml, one of six isolates by < or = 1.0 micrograms of penicillin/ml, and zero of six isolates by < or = 1.0 micrograms cefazolin/ml.
Insights
Propionibacterium acnes, a cause of post-cataract surgery infection, was tested for antibiotic susceptibility. Vancomycin demonstrated potent bactericidal activity, effectively killing all tested isolates.
Area of Science:
- Ophthalmology
- Microbiology
- Infectious Diseases
Background:
- Propionibacterium acnes is a common cause of chronic infectious endophthalmitis.
- This infection can occur after cataract surgery, specifically extracapsular cataract extraction.
- Understanding antibiotic susceptibility is crucial for treating these infections.
Purpose of the Study:
- To determine the antibiotic susceptibility of Propionibacterium acnes isolates from infectious endophthalmitis cases.
- To evaluate the efficacy of penicillin, cefazolin, and vancomycin against these isolates.
Main Methods:
- Six Propionibacterium acnes isolates were obtained from patients with chronic infectious endophthalmitis.
- Antibiotic susceptibility testing was performed using a macrobroth dilution method.
- Minimum bactericidal concentrations (MBCs) were determined at 72 hours.
Main Results:
- All six isolates were susceptible to penicillin, cefazolin, and vancomycin.
- Vancomycin exhibited strong bactericidal activity, killing all isolates at concentrations <= 1.0 microgram/ml.
- Penicillin killed one isolate at <= 1.0 microgram/ml, while cefazolin did not kill any isolates at this concentration.
Conclusions:
- Vancomycin is a highly effective antibiotic against Propionibacterium acnes causing infectious endophthalmitis.
- Penicillin and cefazolin showed limited bactericidal activity at the tested concentrations.
- These findings support the use of vancomycin in treating Propionibacterium acnes endophthalmitis.