Coliforms are important markers of bacterial contamination in recreational waters and have sometimes been reported as antibiotic resistant. Antibiotic resistance may be affected by rain and pollution. Little is known about the antibiotic resistance of coliforms from Southern California beaches. This project examined the numbers of coliforms as well as incidence of antibiotic resistant coliforms in beaches with restricted and non-restricted wave action following dry and wet weather. Samples were collected from the shores of beaches with restricted and non-restricted wave action following dry and wet weather. Total coliforms were selected by membrane filtration onto mEndo agar and then enumerated. Randomly selected isolates from each location were screened for resistance to nine antibiotics by the disk diffusion method and the multiple antibiotic resistance (MAR) index was calculated. Select isolates were subject to minimum inhibitory concentration (MIC) testing to define degree of ampicillin resistance. Numbers of total coliforms were significantly higher following rain compared to dry weather. Total coliforms were not significantly elevated at non-restricted wave action sites. Restricted wave action sites had a 78.45% increase in MAR index following wet weather compared to dry weather. Resistance to ampicillin was observed in almost 50% of isolates and was not significantly impacted by wave action or weather. This study is the first to report on antibiotic resistance of coliforms found in Southern California beaches and highlights that ampicillin resistance is widespread.
|Advisor:||Dillon, Jesse G.|
|Commitee:||Holland, Erika B., Pernet, Bruno|
|School:||California State University, Long Beach|
|School Location:||United States -- California|
|Source:||MAI 81/7(E), Masters Abstracts International|
|Keywords:||Antibiotic resistance, Total coliforms|
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