Modified excised teat model for laboratory screening of teat dips

Area of Science:

• Veterinary Microbiology
• Bacteriology

Background:

• Indigenous microorganisms on excised teats hinder accurate challenge culture enumeration on nonselective media.
• Effective methods are needed to reduce microbial contamination for reliable Streptococcus agalactiae studies.

Purpose of the Study:

• To evaluate physical and chemical treatments for reducing microbial load on excised teats.
• To identify selective and differential media for optimal Streptococcus agalactiae recovery.
• To compare different methods for recovering Streptococcus agalactiae from excised teats.

Main Methods:

• Excised teats underwent physical (autoclaving, boiling, microwaving) and chemical (sodium hypochlorite, hydrogen peroxide, iodophor) treatments.
• Selective media (Edwards, NPC) were screened for Streptococcus agalactiae recovery and bacterial contamination.
• Recovery methods (hand agitation, stomaching, swabbing, syringe rinsing) and time intervals between challenge and teat dip exposure were assessed.

Main Results:

• Physical and chemical treatments were unsuitable for reducing microbial contamination.
• Edwards and NPC agars demonstrated superior recovery of Streptococcus agalactiae.
• Hand agitation and stomaching in neutralizer were the most effective recovery methods.
• A 1-minute or less interval between challenge and teat dip exposure was effective.

Conclusions:

• Selective media, particularly Edwards and NPC agars, are crucial for reliable Streptococcus agalactiae enumeration from excised teats.
• Mechanical methods like hand agitation or stomaching are preferred for sample processing.
• Optimized time intervals enhance experimental efficiency without compromising results.