Download - Dissertation Proposal:
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
Reference: www.Slideshare.com