Related Experiment Videos
Staphylococcus saprophyticus beta-lactamase production and disk diffusion susceptibility testing for three
Antimicrobial Agents and Chemotherapy
|November 1, 1984
Summary
Most Staphylococcus saprophyticus strains produce beta-lactamase, an enzyme that can affect antibiotic susceptibility testing. Current disk diffusion methods may be inappropriate for accurately determining antibiotic resistance in these bacteria.
Area of Science:
- Microbiology
- Clinical Microbiology
- Antimicrobial Resistance
Background:
- Staphylococcus saprophyticus is a common cause of urinary tract infections.
- Accurate antibiotic susceptibility testing is crucial for effective treatment.
- Beta-lactamase production can confer resistance to beta-lactam antibiotics.
Purpose of the Study:
- To assess beta-lactamase production in Staphylococcus saprophyticus strains.
- To correlate beta-lactamase production with antibiotic susceptibility testing results.
- To evaluate the appropriateness of current disk diffusion criteria for S. saprophyticus.
Main Methods:
- Sixty-seven strains of Staphylococcus saprophyticus were tested.
- Beta-lactamase production was determined.
- Minimum Inhibitory Concentrations (MICs) for penicillin, methicillin, and cephalothin were measured.
- Disk diffusion susceptibility testing was performed and correlated with MICs.
Main Results:
- 82% of S. saprophyticus strains produced beta-lactamase.
- 77% of beta-lactamase-producing strains were susceptible by disk diffusion.
- A zone size < 31 mm strongly indicated beta-lactamase production (P = 0.0000008).
- Penicillin MICs were low and not related to beta-lactamase production.
- Oxacillin disk diffusion interpretation showed significant variability.
Conclusions:
- Current disk diffusion criteria for Staphylococcus aureus are inappropriate for S. saprophyticus.
- Beta-lactamase production is common in S. saprophyticus.
- Further evaluation of the clinical significance of beta-lactamase in these strains is needed.