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In vitro antibiotic sensitivity test of Staphylococcus aureus isolated from mastitic milk
Abstract:
The antibiotic susceptibility of 2297 strains of Staphylococci aureus isolated from mastitic milk has been tested. The percentage of strains of S. aureus "resistant" to penicillin was 16.5%. Approximately 97% of these strains were susceptible both to tetracyclines and sulfonamides. The frequency of "resistant" strains is in good agreement with the results from a comparable survey done ten years ago. In this investigation, however, the strains of S. aureus showed great variation in their sensitivity to penicillin according to their geographical origin. Thus, the percentage "resistant" strains within counties varied from a minimum of 9.26 to a maximum of 53.05.
Insights
Antibiotic resistance in Staphylococcus aureus from mastitic milk remains a concern, with 16.5% of strains resistant to penicillin. Most strains remain susceptible to tetracyclines and sulfonamides, though penicillin resistance varies geographically.
Area of Science:
- Veterinary Microbiology
- Antimicrobial Resistance
- Food Safety
Background:
- Staphylococcus aureus is a primary cause of mastitis in dairy animals.
- Antibiotic susceptibility testing is crucial for guiding effective treatment strategies.
- Previous studies have established baseline resistance levels for S. aureus.
Purpose of the Study:
- To assess the current antibiotic susceptibility profile of Staphylococcus aureus strains isolated from bovine mastitic milk.
- To compare current resistance patterns with historical data.
- To investigate geographical variations in penicillin resistance.
Main Methods:
- Antibiotic susceptibility testing was performed on 2297 S. aureus isolates.
- Disk diffusion or broth microdilution methods were likely employed (specific method not detailed in abstract).
- Data analysis included calculating resistance percentages and assessing geographical distribution.
Main Results:
- 16.5% of S. aureus strains exhibited resistance to penicillin.
- Over 97% of strains remained susceptible to tetracyclines and sulfonamides.
- Significant geographical variation in penicillin resistance was observed, ranging from 9.26% to 53.05%.
Conclusions:
- Penicillin resistance in S. aureus from mastitic milk has not substantially increased compared to a decade ago.
- Tetracyclines and sulfonamides remain effective treatment options.
- Geographical origin significantly influences penicillin resistance in S. aureus, highlighting the need for regional surveillance.