Characterization of Dutch Staphylococcus aureus from bovine mastitis using a Multiple Locus Variable Number Tandem...

Area of Science:

• Microbiology
• Veterinary Science
• Genetics

Background:

• Current typing methods for Staphylococcus aureus, a common cause of bovine mastitis, possess significant limitations.
• Accurate and efficient bacterial typing is crucial for epidemiological surveillance and control of mastitis outbreaks in cattle.

Purpose of the Study:

• To evaluate the efficacy of a 6-locus Multiple Locus Variable Number Tandem Repeat Analysis (MLVA) scheme for typing Staphylococcus aureus.
• To compare the discriminatory power and predictive value of MLVA against established methods like Multi Locus Sequence Typing (MLST), spa-typing, and Pulsed-Field Gel Electrophoresis (PFGE).

Main Methods:

• A 6-locus MLVA scheme was applied to 85 bovine mastitis isolates of Staphylococcus aureus.
• Typing results were compared with MLST, spa-typing, and PFGE using measures like Simpson's Index of Diversity.
• The predictive accuracy between MLVA and spa-typing was assessed using the Adjusted Rand index and Wallace's coefficient.

Main Results:

• MLVA identified 18 distinct types (MTs), demonstrating good discriminatory power (Simpson's Index: 0.781), falling between MLST and spa-typing.
• Pulsed-Field Gel Electrophoresis (PFGE) exhibited the highest discriminatory power (0.887), while spa-typing had the lowest (0.69).
• MLVA proved highly predictive for spa-type, suggesting strong concordance, and was noted for its speed and cost-effectiveness.

Conclusions:

• The evaluated MLVA scheme is a suitable, rapid, and economical method for typing bovine-associated Staphylococcus aureus.
• MLVA offers a valuable alternative for epidemiological studies, complementing other methods like PFGE and MLST.
• Understanding genetic variations, such as those near SIRU05, is key to optimizing PCR-based typing strategies.