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Antibiotic Resistance in Septic Effluent . 2011 National Environmental Health Association Meeting Crispin Pierce, Sasha Showsh, and Eli Gottfried (faculty) Tola Ekunsanmi , Michael Checkai , Jay Nielsen, Jacob Schafer, Michael Servi and Matt Haak (students) University of Wisconsin-Eau Claire.

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Antibiotic Resistance in Septic Effluent

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Antibiotic Resistance in Septic Effluent

2011 National Environmental Health Association Meeting

Crispin Pierce, Sasha Showsh, and Eli Gottfried (faculty)

TolaEkunsanmi, Michael Checkai, Jay Nielsen, Jacob Schafer, Michael Servi and Matt Haak (students)

University of Wisconsin-Eau Claire


  • Background

  • Antibiotic Resistance from Land Spreading?

  • Antibiotic Resistance in Septic Effluent

    • Big box store

    • Chain restaurant

    • Rehabilitation and Convalescent Center

  • Surveillance and Control

  • Summary of Control Measures


  • Antibiotic resistance is evident when a drug can no longer inhibit the growth of the target bacteria.

  • Resistance may be natural or as a result of mutation of existing genetic material acquiring new genetic material.

  • Feed additives, including antibiotics, are used to promote growth of livestock enter the food chain.

  • Widespread human use of antibiotics is also associated with antibiotic resistance.

  • According to the National Nosocomial Infections Surveillance (NNIS) System data on intensive care units (ICUs) in the U.S, 28.5% of enterococci associated with nosocomial infections were resistant to vancomycin, 31.9% of Pseudomonas aeruginosawere resistant to ceftazidime and 60% of Staphylococcus aureus isolates were resistant to methicillin (i.e. MRSA) (1).

  • More than 80 pharmaceuticals and drug metabolites, have been measured in μg/l-levels in sewage samples and downstream surface waters. (2)

  • Recent research has shown certain bacteria may survive on a diet of the antibiotic Vancomycin. (3)

  • The improper disposal and overuse of antibiotics accelerates the spread of antibiotic-resistant bacteria.

  • Nontherapeutic use of antibiotics in animal production is estimated to be the cause of about 70% of antibiotic resistance (4).

When food animals are treated with antibiotics to speed growth or compensate for dirty, crowded and stressful conditions, bacteria resistant to these drugs proliferate and enter humans through meat consumption. Similarly, over-prescription and improper disposal of antibiotics lead to ground and surface water contamination, and entry into humans from drinking water. (Photo:

Transmission of antibiotic-resistant bacteria is highest in confined populations such as hospitalized patients, college students living in dormitories, prison inmates, and athletes (football players on artificial turf have 15-fold higher prevalence rates). Populations most likely to develop disease and death are children, elderly, and immune-compromised individuals. (Photo:

These bacteria in turn cause extensive disease and death: methicillin-resistant staphylococcus aureus (MRSA) alone causes 15–20,000 deaths in the United States each year (4).

Antibiotic Resistance from Land Spreading?

Hypothesis: Agricultural fields receiving land spreading of septic system effluent will have higher levels of antibiotic resistant bacteria than fields without spreading.

Materials and Methods

Thirteen soil samples (7 control and 6 treated) were collected from a crop field near Eau Claire treated with septic system effluent (Figs. 1 and 2). These samples were mixed with water and plated on Colombian Blood Agar and four antibiotics (chloramphenicol, tetracycline, erythromycin and ampicillin, Fig. 3).

Fig. 1 Land spreading of septic tank effluent.


Although the fraction of antibiotic-resistant colonies tended to be higher for control vs. treated samples, this apparent difference did not reach a significance of p<0.05 (one-tailed t-test, equal variance, Fig. 4).

Fig. 4 Colony growth and fraction of antibiotic resistance in control and treated (septic effluent-applied) samples for five antibiotics.


In this small study, treatment of an agricultural field with septic system effluent did not significantly change the fraction of bacteria that were resistant to five antibiotics (Kanamycin, Tetracycline, Eosine Methylene Blue, Erythromycin and Ampicillin).

Antibiotic Resistance in the Effluents from a Big Box Store, Chain Restaurant and Convalescent Home

Bacterial antibiotic resistance generated from a large retail store, small chain restaurant and convalescent home was measured.  Several samples of effluent from the respective septic systems were analyzed for bacterial resistance to ampicillin, kanamycin, tetracycline, and erythromycin. 


The restaurant contained higher levels of resistance to ampicillin, kanamycin, and tetracycline than the store or convalescent home, with an average of 51.79%, 27.54%, and 30.78% of microbial growth resistant to the respective antibiotics. 

Erythromycin resistance was highest in effluent discharged from the convalescent home at 22% compared to the store at 7.00% and restaurant at 2.87%.


Our research analyzed wastewater effluent from a rehabilitation and convalescent facility, a “big-box” store, a local chain restaurant, and septic sewage spread agricultural and untreated soils. We found that wastewater and soil samples contained fractions of antibiotic resistant bacteria from 0.5—52%.

Surveillance and Control

Wisconsin State Division of Health:

  • Information for Health Care Providers

  • Antibiotic Resistance Report

Summary of Control Measures

  • Surveillance of hospital and non-hospital incidence and prevalence.

  • Appropriate use of antibiotics:

    • Use only when needed

    • Proper disposal

    • Legislation to limit non-therapeutic use in animals.

  • Sanitation


1. Wisconsin Division of Public Health Bureau of Communicable Diseases and Preparedness Guidelines for Prevention and Control of Antibiotic Resistant Organisms in Health Care Settings, September, 2005.

2. Herberer, Thomas. "Toxicology Letters: Occurrence, Fate, and Removal of Pharmaceutical Residues in the Aquatic Environment: a Review of Recent Research Data." ScienceDirect. 15 Mar. 2002. Toxicology Letters. 7 Apr. 2008

3. "Antibiotic-eating germ alarms doctors - Enterococcus faecium bacterium survives on diet of the antibiotic vancomycin - Biomedicine - Brief Article". Science News. Dec 21, 1996.

4. Pew Charitable Trusts. “Human Health and Antibiotic use in Industrial Farming” 2010.

Additional References

Paterson, David . "Update on Antibiotic Resistance in Hospitals." The Prevalence of Antibiotic Resistance in the Hospital Setting. 2006. 20 Apr 2007 <>.

Fridkin, Scott K. et al. "Temporal Changes in Prevalence of Antimicrobial Resistance in 23 U.S. Hospitals." Emerging Infectious Diseases Vol. 8, No. 7,(2002): 697-701.

Lipsitch, Marc. "The epidemiology of antibiotic resistance in hospitals:Paradoxes and prescriptions." PNAS vol.97(2000): 1938-1943.

Thanks for Your Attention

Contact Information

  • Crispin H. Pierce, Ph.D.

  • Associate Professor / Program Director

  • Department of Public Health Professions

  • 244 Nursing

  • University of Wisconsin - Eau Claire

  • Eau Claire, WI 54702-4004

  • (715) 836-5589



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