Recovery of Antibiotic Resistant Staphylococcus and Streptococcus spp. 

from Landfill Leachate

Jenny Will, Neil Kirkpatrick and James McGaughey

Department of Biological Sciences, Eastern Illinois University, Charleston, IL

Introduction and Purpose

Growing concerns about antibiotic resistant bacteria continue to spread beyond health care facilities to encompass areas accessible to the public. Landfills are a potential source for accumulation of such microbes, which may be dispersed to other areas via leachate.

The purposes of our investigation were to determine whether Staphylococcus and Streptococcus were present in landfill leachate and adjacent groundwater and to test their resistance to commonly prescribed antibiotics.

	Landfill
	Strep plate

Methods

Landfill leachate and adjacent groundwater samples were aseptically collected from wells at a regional landfill site. Cells were collected by membrane filtration (0.22mm filters). 10, 1, and 0.1 mL portions were filtered. Presumptive Staphylococcus spp. were isolated on Vogel-Johnson agar augmented with 1% tellurite solution. Suspect colonies were Gram stained, tested for catalase production and transferred to Mannitol Salt agar for confirmation. Presumptive Streptococcus spp. were isolated on Bile Esculin Azide agar. Suspect colonies were Gram stained for confirmation.  Confirmed colonies of Staphylococcus and Streptococcus were transferred to flasks of Brain-Heart Infusion broth. Resistance to antibiotics for Staphylococcus and Streptococcus was determined following the Mueller-Hinton protocol.

	Samples from groundwater and leachate.
	Filter membrane apparatus

Results

	Staphylococcus spp. on Vogel-Johnson agar.
	Streptococcus spp. on Bile Esculin Azide agar.
	Bile Esculin Azide plates (bottom view) showing hydrolysis of esculin.

	Staphylococcus resistant to antibiotics tested
	Streptococcus resistant to antibiotics tested

3.4% of colonies recovered on Vogel-Johnson agar were confirmed as Staphylococcus spp.

13% of colonies recovered on Bile Esculin Azide agar were confirmed as Streptococcus spp.

Staphylococcus spp. demonstrated resistance to 33% of the antibiotics being tested.

Streptococcus spp. demonstrated resistance to 44% of the antibiotics being tested.

Summary

Based on results of concurrent studies, Staphylococcus and Streptococcus spp. represent a very small proportion of the total population of bacteria found in landfill leachate.  Antibiotic resistant strains of Staphylococcus and Streptococcus spp. exist in leachate and groundwater.  A commonality exists between Staphylococcus and Streptococcus spp. and their antibiotic resistance.

References

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Acknowledgements

Funding and support from the College of Sciences; Department of Biological Sciences and the Undergraduate Research Council, Eastern Illinois University

Matt Gresk for his help and support with the poster design.