DISSERTATION PROPOSAL:

Abby L. H. Maples, MPH

Antibiotic-resistant Staphylococcus aureus: Investigation of a poultry reservoirDepartment of Occupational & Environmental Health

Sept.10, 2010

Introduction

Background Significance

Goals Specific Aims Limitations of Current Literature &

Research Research Design & Methods Strengths & Limitations

Background

Staphylococcus aureus Signs & symptoms Methicillin-resistant S. aureus (MRSA)

Hospital 94,000 infections (Klevens, 2007) 18,000 deaths (Klevens, 2007)

Community 1% of US population colonized (Graham, 2006; Kuehnert, 2006; Shorr, 2007)

Livestock

http://www.medicinenet.com/mrsa_infection/page2.htm

Antibiotic-resistant S. aureus & Animals

S. aureus can cause infection in animals (Baptiste, 2005; De Neeling, 2007; Juhasz-

Kaszanyitzky, 2007; Khanna, 2008; Smith, 2009; Van Loo, 2007; Weese, 2005; Weese, 2006) Role of humans

Transient carriers or reservoirs? Role of animals

Endemic? Swine herds studied Livestock-associated MRSA increasing

Antibiotic-resistant S. aureus in Environmental Samples

Airborne transmission Colonization role?

Previous airborne transmission studies (Gibbs, 2004; Gibbs, 2006)

Surface contamination Meat contamination

(De Boer, 2009; Hanson, in press)

http://www.takepart.com/news/tag/anti-factory-farming

Goals

Long-term goal Understand ecology & epidemiology of

antibiotic-resistant (AbR)S. aureus Objective

Characterize ecology & epidemiology of AbR S. aureus

Central hypothesis Workers in close proximity to poultry are at risk

of occupational exposure to AbR S. aureus Farmers in contact with poultry will be colonized

with MRSA

Specific Aims

1. Establish the prevalence & molecular characteristics of AbR S. aureus on poultry farms

2. Establish the prevalence & molecular characteristics of AbR S. aureus in poultry processing facilities

3. Determine risk factors for presence of AbR S. aureus on farms or processing facilities

Limitations of Current Literature S. aureus is rapidly changing Previous studies in chickens did not

include workers Epidemiologic studies in poultry have

not been conducted in U.S.

http://www.sciencedaily.com/releases/2009/03/090316120846.htm

Preliminary Studies

Prevalence of MRSA in Iowa & Illinois swine

18 swine farms in Iowa & Illinois (Smith, 2009) 9 each – confined animal feeding

operations (CAFOs) & antibiotic-free systems

5/18 (27.7%) farms positive for MRSA All CAFOs (55.5%, 5/9)

Prevalence in swine 43/428 (10.0%) Prevalence in humans 29/89 (32.6%)

Humans working at CAFOs (45.3%, 29/64)

Research Design & Methods

Farm Description Broilers, layers, and turkeys Estimate 40% (± 5.0%) prevalence in

poultry 95% confidence interval, 80% power = 600

animals 20 animals from 30 farms (10 each) Convenience Sample

Estimate 1-2 employees per farm Goal to enroll 60 humans

http://newshopper.sulekha.com/turkey-farm_photo_1063248.htm

Research Design & Methods Continued

Sample Collection IRB & IACUC Approved Humans

Nasal & throat Swabs Comparison, non-exposed group

Poultry Choanal (palatine) cleft & cloaca swabs

Air Sample Collection 6-stage Andersen Viable Cascade Impactor

Research Design & Methods Continued

Processing Facility Sample Collection Estimate 25% prevalence in processing

facilities Surface & worker swabs of facility

Occupational Exposure Questionnaire Animal exposure in last year Demographic & behavioral questions

Farm Owner/Manager Questionnaire Farm-specific questions

Research Design & Methods Continued

Bacterial Growth 6.5% Staph enrichment broth, CNA &

CHROMagar Microbiology

Gram stain, catalase, coagulase, S. aureus latex agglutination assay

MRSA confirmed by penicillin binding protein presence

Diagnostic Schematic

Research Design & Methods Continued

Molecular Typing Spa typing PVL PCR Multilocus sequence typing (MLST) Pulsed-Field Gel Electrophoresis (PFGE)

Antibiotic Resistance Testing Broth dilution (CLSI standards) Tested for susceptibility

Research Design & Methods Continued

Data and Statistical Analysis Double-entry into databases

Excel, Access, and Teleform Verifier Unique specimen numbers Multivariate modeling of risk factors (SAS)

Logistic regression Cochran-Armitage trend test

Strengths & Limitations

First study of S. aureus in live poultry & workers in US

Well qualified & experienced team

Collaboration with ISU Iowa is a national

leader in eggs and turkey production

Convenience, single-time samples (not representative)

Pilot study Limited geography Limited farmer

enrollment

Strengths Limitations

Impact & Benefit to Field

Assess infectious disease risks Provide recommendations for

preventative measures Establish prevalence and dominant

molecular types of S. aureus in poultry Create potential implementations to

prevent spread of S. aureus in rural Iowa

Three Publishable Paper Topics Literature review of poultry diseases Antibiotic resistant Staphylococcus aureus:

Investigation into a poultry reservoir Staphylococcus aureus in environmental

samples and humans: Two poultry production facilities in Iowa(?)

Airborne Staphylococcus aureus in (10) poultry barns (?)

**Open for discussion

Project Timeline

Oct 2010 – Sept 2011: Farm Sampling Dec 2010 – June 2012: Molecular analysis

& antibiotic resistance testing June – Sept 2012: Finish analysis & draft

manuscript

Oct-Dec 2010

Jan-March 2011

April-June 2011

July-Sept 2011

Oct-Dec 2011

Jan-March 2012

April-June 2012

July-Sept 2012

Farm Sampling

Molecular analysis & antibiotic resistance testing

Finish analysis & draft manuscript

Questions, Comments, or Concerns?

http://ehsmanager.blogspot.com/2009/05/bacteria-create-aquatic-superbugs-in.html