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Susceptibility of Staphylococcus aureus and Staphylococcus epidermidis to 65 antibiotics
Abstract:
The susceptibilities of 36 recent isolates of Staphylococcus aureus and 35 recent isolates of Staphylococcus epidermidis were determined against each of 65 antimicrobial agents and against two of them in combination. Rifampin was the most active of all the agents tested against both S. aureus and S. epidermidis. Among the penicillins, cloxacillin, dicloxacillin, and nafcillin were most active, although benzylpenicillin and phenoxymethyl penicillin were more active against susceptible strains. Cephaloridine was the most active of the cephalosporins, and sisomicin was the most active aminoglycoside. Minocycline was more active than the other tetracycline analogues tested. Among the macrolide-lincomycin compounds in clinical use, clindamycin was more active, and lincomycin was less active than erythromycin. The synergy of trimethoprim-sulfamethoxazole was more striking against S. aureus than against S. epidermidis. The median minimal inhibitory concentrations of the penicillins, cephalosporins, and aminoglycosides were lower against S. aureus, whereas the minimal inhibitory concentrations of the tetracyclines were lower against S. epidermidis.
Insights
Rifampin demonstrated the highest activity against both Staphylococcus aureus and Staphylococcus epidermidis. Susceptibility testing revealed varying efficacy among different antibiotic classes for these common bacteria.
Area of Science:
- Microbiology
- Infectious Diseases
- Pharmacology
Background:
- Staphylococcus aureus and Staphylococcus epidermidis are significant human pathogens.
- Antimicrobial resistance necessitates ongoing surveillance of bacterial susceptibility patterns.
Purpose of the Study:
- To evaluate the in vitro activity of a broad spectrum of antimicrobial agents against recent clinical isolates of S. aureus and S. epidermidis.
- To compare the efficacy of individual agents and combinations.
Main Methods:
- Susceptibility testing of 36 S. aureus and 35 S. epidermidis isolates.
- Evaluation against 65 individual antimicrobial agents and selected combinations.
- Determination of minimal inhibitory concentrations (MICs).
Main Results:
- Rifampin exhibited the highest overall activity against both species.
- Cloxacillin, dicloxacillin, and nafcillin were the most potent penicillins; cephaloridine and sisomicin were the most active cephalosporin and aminoglycoside, respectively.
- Minocycline was superior among tetracyclines, and clindamycin among macrolide-lincomycin compounds. Trimethoprim-sulfamethoxazole showed notable synergy against S. aureus.
Conclusions:
- Rifampin is a highly effective agent against contemporary S. aureus and S. epidermidis isolates.
- Differential susceptibility patterns exist between S. aureus and S. epidermidis for certain antibiotic classes, influencing treatment choices.