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Selective growth of Staphylococcus aureus from flushed dairy manure wastewater using acriflavine-supplemented
J A Davis1, S R Farrah, A C Wilkie
1Department of Microbiology and Cell Science, University of Florida-IFAS, Gainesville, FL 32611-0960, USA.
Aims:
To investigate the use of mannitol salt agar (MSA) supplemented with acriflavine for selective growth and quantification of Staphylococcus aureus from flushed dairy manure wastewater (FDMW).
Methods And Results:
Minimal inhibitory concentrations of acriflavine in MSA were determined by comparing the growth of S. aureus subsp. aureus (ATCC 33591) and Staphylococcus epidermidis (ATCC 155) in pure culture. Acriflavine concentrations of 1.3, 1.4 and 1.5 mg l(-1) reduced CFU of S. epidermidis by 43%, 55% and 87%, respectively, while CFU of S. aureus subsp. aureus were only reduced by 15%, 20% and 26% at the respective concentrations of acriflavine. MSA supplemented with 1.5 mg l(-1) acriflavine was tested for selective growth of indigenous S. aureus from three grab samples of FDMW. Acriflavine concentrations of 1.5 mg l(-1) reduced background flora without significantly reducing (P < 0.05) indigenous S. aureus counts.
Conclusions:
Acriflavine-supplemented MSA provides an effective media for selective growth and quantification of indigenous S. aureus from FDMW in the presence of high levels of background microflora.
Significance And Impact Of The Study:
S. aureus is implicated for mastitis infections in dairy cows. Therefore, a reliable means for monitoring and detecting the organism in FDMW provides a tool for measuring the effectiveness of treatment for reducing S. aureus levels and implementing flushwater recycling without affecting herd health.
Insights
Acriflavine-supplemented mannitol salt agar (MSA) effectively selects for Staphylococcus aureus in dairy manure wastewater. This method allows accurate quantification of S. aureus, aiding in mastitis control and water recycling.
Area of Science:
- Microbiology
- Environmental Science
- Veterinary Science
Background:
- Staphylococcus aureus is a significant pathogen causing mastitis in dairy cows.
- Effective monitoring of S. aureus in dairy manure wastewater (FDMW) is crucial for herd health and water management.
- Existing methods may struggle with high background microflora in FDMW.
Purpose of the Study:
- To evaluate mannitol salt agar (MSA) with acriflavine for selective isolation and quantification of Staphylococcus aureus from FDMW.
- To determine optimal acriflavine concentrations for inhibiting background flora while preserving S. aureus.
Main Methods:
- Minimal inhibitory concentrations of acriflavine were determined for S. aureus and Staphylococcus epidermidis.
- Mannitol salt agar (MSA) was supplemented with acriflavine at 1.5 mg/L.
- The supplemented MSA was tested on indigenous S. aureus in FDMW samples.
Main Results:
- Acriflavine at 1.5 mg/L significantly inhibited Staphylococcus epidermidis growth (87% reduction) while minimally affecting S. aureus (26% reduction).
- Acriflavine-supplemented MSA reduced background flora in FDMW samples.
- Indigenous S. aureus counts were not significantly reduced (P < 0.05) by 1.5 mg/L acriflavine.
Conclusions:
- Acriflavine-supplemented MSA is an effective medium for the selective growth and quantification of indigenous S. aureus from FDMW.
- This method provides a valuable tool for monitoring S. aureus levels in dairy wastewater.
- It supports assessing treatment efficacy and safe flushwater recycling to protect herd health.
