A Comparative Study of Methicillin Resistant
Staphylococcus aureus Nasal Carriage Rates
Between Veterinarians and Veterinary Technicians
Diane Hartman, DVM
Tamarah Adair, PhD
Amanda Hartman, BS
Purpose
1. Determine the prevalence of MRSA carriage among veterinarians, veterinary technicians and others
at a Fall 2008 veterinary conference.2. Determine antibiotic sensitivity patterns
of Staphylococcus aureus isolates.3. Determine the oxacillin MIC for each
MRSA sample.4. Distinguish between HA-MRSA and CA-
MRSA based on PCR and gel electrophoresis.
Introduction
CDC reports 25-30% of the population harbors Staphylococcus aureus in their nasal passages
1-3% carry MRSA.
Methicillin Resistant Staphylococcus aureus
• Emerging opportunist in human and veterinary medicine
skin and soft tissue infections
• Transferred by direct contact with carriers or infected individuals
• Antibiotic resistance is common
• Reverse zoonosis
Hospital Associated MRSA or Community Associated MRSA?
Determined by:source of exposure
patient history antibiograms
PCR/Pulse field gel electrophoresis
Hospital Associated MRSA
Risk Factors•Hospitalization•Dialysis •Prolonged antibiotic use
•Long-term care
Multidrug Resistant
http://www.msc.navy.mil/comfort/katrina/graphics/Dialysis.jpg
Reuters
Community Associated-MRSA
• Cases arise sporadically • At risk groups
prisoners young children contact sports participants Immune compromised
usually susceptible to many different antibiotics
• Panton-Valentine leukocidin
Background
• In a 2007-2008 study the prevalence of MRSA was 4X greater in a Texas veterinary population than in an undergraduate population
• Veterinarian MRSA carriage rate higher than normal population (DVM News 2007)
• Canine-Human MRSA transmission (EID2004)
• Feline-Human MRSA transmission (NEJM 2008)
• Equine-Human transmission of MRSA (EID 2006)
Survey and Consent FormsSurveys
determine possible sources of exposure
recent surgery or hospitalization
volunteer in hospital, day care, nursing home
analyze common risk factors
travel, antibiotic use, recent skin infection, public gym, contact sports
JMP computer program was used to evaluate potential risk factors
Consent forms - required for each participant
Methods
Nasal swabs to
mannitol salt agar
Identify Mannitol fermenters that are Gram + cocci
Catalase +
Coagulase +
Antibiotic Sensitivity TestingKirby-Bauer Method
• Antibiotics tested:Amikacin NeomycinCiprofloxacin NitrofurantoinClindamycin OxacillinDoxycycline PenicillinErythromycin RifampinGentamicin Trimethoprim/Sulfa
• ATCC Staphylococcus aureus 25923
Kirby BauerOxacillin R
Oxacillin MIC/E Strips
Molecular AnalysisMEC CCR-all ccr type 2
LADDER
B A
MSSA and MRSA Carriage Rates
# MSSA MRSA
Total population
276 48
(17.4%)
17
(6.2%)
Veterinarians 142
(51.4%)
27
(19%)
4
(2.8%)
Vet techs 102
(37%)
13
(12.7%)
11
(10.8%)
Other 32
(11.6%)
8
(25%)
2
(6.25%)
Survey Results
• Average age group was 30-39 (32%)• Average time in practice was <10 years
(45%)• 74 males (26%) and 203 females (74%)• 227 (82%) treated mainly small animals or
Small animal with exotics• 13 (4.7%) treated mainly large animals• 15 (5.4%) were in education• 21 ( 7.6%) were in the “other” category
Carriers Based on Gender, Role, and Practice Type
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Male Female Vet Tech Other SA only mix <SA SA
w/exotics
LA Education Other
Gender Role Practice Type
Risk Factor
MRSA
Carrier
NonCarrier
Carriage Based on General Risk Factors
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
yes no yes no yes no yes no yes no yes no
Smoking Work with Kids <12 Travel Workout in Public Gym Sores Scratches
Risk Factor
MRSA
Carrier
NonCarrier
Antibiograms
• All MRSA isolates were sensitive to Amikacin, Gentamicin, Doxycycline, and Trimethoprim/Sulfamethoxazole.
• All MRSA isolates were resistant to oxacillin and penicillin.
• MRSA isolates demonstrated 7 antibiogram patterns.
MRSA N FM Ox Ra E CC Cip P
1 R S R S R S R R
2 S S R S S S S R
3 S S R S S S R R
4 R S R S R R R R
5 S S R S S S R R
6 S R R R R R S R
7 R S R S R R R R
8 S S R S S S S R
9 S S R S S S S R
10 R S R S R R R R
*11 R S R S R S S R
*12 R S R S R S S R
13 R S R S R S S R
14 S S R S R S S R
15 R S R S R S R R
16 R S R S R S R R
17 R S R S R R R R
Oxacillin MIC/E Strips
MRSA MIC (µg/mL)
1 64
2 48
3 >256
4 >256
5 128
6 >256
7 192
8 64
9 32
10 >256
11 128
12 128
13 48
14 128
15 192
16 128
17 192
Molecular Analysis - HA or CA MRSA?
MEC CCR
LADDER
B A16 were type 2 ccr.
3 were Class A mec
13 were Class B mec
Class A mec with type 2 ccr are Type II - HA strains
Class B mec with type 2ccr are Type IV -CA strains
HA or CA MRSA?
• Samples 4, 10, 16 were HA strains – All 3 Vet Techs– R to 5 or more antibiotics– MIC all 128 µg/ml or greater
• 13 samples were CA strains– 9 R to 4 or fewer antibiotics– MIC 32-192 µg/ml
• 1 strain was not typeable with the primers used (vet tech with MIC>256 µg/ml and R to 6 antibiotics)
Discussion
• None of the survey risk factors were significantly correlated with carriage rates for MSSA or MRSA
• Veterinary Technicians are – 10 times more likely than the general
population and more than 3 times as likely as veterinarians to carry MRSA.
– 3 technician samples were HA-MRSA (Type II)– 6 technician samples were CA-MRSA (Type IV)– 1 tech sample was not typed
• All 4 vet samples were CA-MRSA (Type IV)• 2 “other” were CA-MRSA (Type IV)
Discussion
Potential Risk Factors for Technicians?1. Spend more time in the exam room with
clients and pets2. Spend more time with their face close to the
patient/pet3. Spend more time face to face with clients in
the exam room and waiting area4. More likely to interact with client’s children5. More likely to perform dental prophys on pets6. More likely to clean cages/kennels7. More likely to clean ears and/or bathe pets
Prevention
WASH YOUR HANDS!Don’t share towels or other
personal items.Cleanse fresh wounds and
keep wounds covered.Wear appropriate PPE for
the task,e.g. dentals - lab coats, gloves, mask/face shield.
FUNDING
Supported by the Baylor Undergraduate Research and Scholarly Activities Small Grant Program
and the Vice Provost for Research
Department of Biology Baylor University
Acknowledgements
STUDENT LAB ASSISTANTS:Amanda Hartman
Ly NguyenTrevin Rube
Brooklyn SandvallAyla Farris
Kevin Farquar