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