Charles P. Gerba

Departments of Soil, Water and Environmental Science

and

Epidemiology and Environmental Health

University of Arizona

Tucson, AZ

Percentage of Disease by Transmission Route

Fomite

Drinking water

Animal to human Person to person

Aerosol

Food

Recreation

?%

?%?%

?%

?%

?%?%

What are Fomites?

➢ Inanimate objects involved in the spread of disease

Role of Fomites in Transmission of a Disease

Sick person sneezes, coughs and pathogens fall on fomite or get aerosolized

Person picks up pathogen through contaminated fomite

Person touches nose or eyeswith contaminated fingers and

becomes infected with pathogenPathogen falls on fomites

e.g. phone, computer

4

Life in the 21st Century

➢ Most of our time is spent indoors (80 - 90%)

➢ More people work in offices than ever before

➢ We travel more than ever before

➢ We spend less time cleaning than the last generation (50% less than 50 years ago)

➢ We are less clean (e.g., laundry practices)

➢ We spend more time in public places

➢ We are more mobile and have more electronic equipment (e.g., cell phones, ipods)

➢ We share more common surfaces (fomites) with more people than ever before in history

Cleaning vs. Hygiene

Cleaning is the removal of unwanted matter

Hygiene is reducing therisks of infection

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Cleaning vs. Hygiene

• Meta-analysis of impact of cleaning and disease reduction indicates normal household cleaning may increase illness rates (Paul Hunter)

Is cleaning hazardous to your health?

Cleaning alone may increase risks by spreading pathogens

Coliform Bacteria and Escherichia coli (E. coli)

• Coliform bacteria and E. coli are found in feces and their presence on surfaces indicates contamination by feces and the potential presence of disease causing microorganisms

Colonies with a green metallic sheen are counted as total coliforms

m-Endo Agar

Enteric Bacteria (Coliforms) in the Home by Location

-2

-1

0

1

2

3

4

5

6

7

Ge

om

etr

ic m

ea

n p

er

cm

2 o

r p

er

mL

Bath

Sink

Kitchen

Floor

Bath

CounterBath

FloorToilet

Seat

Kitchen

Sink

Sponge Cutting

Board

Bacteria by the Numbers

(per square inch)

➢200,000 – Carpeting

➢49 –Toilet Seat

➢1,686 Kitchen counter top

➢2,546 Kitchen tile floor - home

➢18,025 Bathroom floor - home

Dangers of being a Couch PotatoRoutes of Germ Exposure - Fabrics

aerosol Inhaled

Hand

Transfer

Tra

nsfe

r to C

loth

ing

Hand Transfer

How fast does a microbe move in the indoor environment?

The VirusBacteriophage MS-2

-~23 nm in diameter

-single stranded RNA

-no lipid layer

-similar in shape and size to the cold

virus (rhinovirus) and norovirus

-commonly used as a

model for disinfectant

testing

Virus spread in a Home

• Add MS-2 virus to one hand of and adult in a family of 4 to 6 (does not know hand has been inoculated) – on a weekend day

• Test hands and surfaces in the house after 4 hours

• Results

Virus detected on the hands of all family members hands in the household

Virus detected on ~98% of the sites tested positive for virus including

» Kitchen table, countertops

» Bathroom counters

» Living room light switches, TV remotes

» Bedroom door handle, sheets, light switchesTamimi et al 2014

The Importance of Cleaning Tools in the

Spread of Germs

Bacteria in Offices

Nu

mb

er

of

Ge

rms

pe

r Sq

uar

e In

ch

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Quat Wipe / Hand Sanitizer Intervention In an Office Building

• Add a bacterial virus to the entrance door handle of an office building with 80 persons

• Collect samples after 2, 4 and 7 hours of fomites and hands

First place virus

detected is the

coffee break room

Impact of intervention on Occurrence of Virus on

Employees’ Hands

Parainfluenza on Office Fomites Fall 2004 –

The virus could be detected on ~30% of all surfaces

Percentage of Fomites Positive for Parainfluenza

0

10

20

30

40

50

60

70

New York San

Fransico

Atlanta Chicago Tucson Total

Conference

Rooms

Offices

Cubicals

The Effectiveness of a Chemical Disinfectant Depends on a Number of Important Factors

• Human behavior

Cleaning habits/training, selection of cleaning tools

• Target microorganisms

Bacteria, viruses, molds

• Type of disinfectant

Bleach, quat, hydrogen peroxide, silver, natural product (Thymol)

• Formulation of the disinfectant

Some formulations will not kill all the types of microorganisms you are targeting

The Effectiveness of a Chemical Disinfectant Depends on a Number of Important Factors

• Bioburden

Surfaces need to be cleaned of organic matter before application of the disinfectant

• Method of application

Spray and wipe, cloth soaked in disinfectant, disinfectant wipe, type of cleaning cloth (some have a high demand for the disinfectant)

• Dwell (contact) time

Varies greatly with the type of disinfectant

• Type of fomite

Corrosiveness of the disinfectant, cloth materials, surface roughness

Most Common Disinfectants Used in Homes,

Public Places and Hospitals/Health Care

Facilities

➢ Quats (take 10 minutes)

➢ Chlorine Bleach

➢ Hydrogen Peroxide

Fabric

• Collected 3 cloths each from 10 different hospitals in Arizona

• Tested cloths by wetting in trypticase soak broth and then squeezing out the liquid and testing for total bacteria, coliform bacteria, spore formers, MRSA and C. difficile

Study of Bacteria in Reusable Cleaning Cloths in Hospitals

Average Number of Bacteria in Towels used

to Clean Patients’ Rooms (before use)

Hospital Total Bacteria Coliforms*

1 12,600 1

2 63 0

3 6,310 2

4 7,943 0

5 31,622 0

6 100,000 20

7 1,000 0

8 5,012 0

9 6,310 0

10 398 25

*E. coli was identified in two towels

Effect of Cleaning Cloth Material

on Bacteria in the Cloth

Organism Cotton Microfiber P-value

Total

bacteria

1,995 24,547 0.01

Coliforms 1 6 0.0002

Molds 1 47 0.001

Effect of Disinfectant Application Method

Organism Soaked Sprayed P-value

Total

bacteria

2,239 104,713 0.01

Coliforms 1 18 >0.0001

Mold 1 2,188 >0.0001

Spores 15 4,074 0.04

Dry Steam Vapor Intervention

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Study by Sexton, Tanner, Maxwell, and Gerba:

“Reduction in microbial load on high-touch surfaces in hospital rooms using a steam vapor disinfection system.”

Research Sponsor - Advanced Vapor Technologies

Water is Transformed into Super-heated Low-moisture Steam

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Advantages of a Saturated Steam Vapor Disinfection System

• No chemicals

• Works on fabrics

• Rapid kill of microorganisms - seconds

• Works against viruses, bacteria (spores), molds

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Dry Steam Vapor Intervention – Results A

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The steam vapor device reduced total microbial and pathogen loads to below detection in most instances…

Research Sponsor - Advanced Vapor Technologies

Rapid kill of microbes

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Dry Steam Vapor Intervention – Results B

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Reduced total coliforms by 83% (40/48) to 13% (6/48). Reduced MISA (12/48) and MRSA (3/48) to below detection.

Research Sponsor - Advanced Vapor Technologies

Dry Steam Vapor Intervention – Results C

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Reduced bacterial levels by >90% and reduced pathogen levels on most surfaces to below the detection limit.

Research Sponsor - Advanced Vapor Technologies

Dry Steam Vapor Intervention – Research Conclusion

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May reduce microorganisms without the drawbacks associated with chemicals, and decrease cross-contamination.

Research Sponsor - Advanced Vapor Technologies

Impact on Bioburden and Biofilm

Sponsored study at the University of Michigan

Dry Steam Vapor technology rapidly kills highly resistant biofilms with greater than 99.95 percent killing efficiency in a three-second treatment, and to a non-detectable level in a less than 10 second treatment.

Summary of Technology

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• No chemicals

• Rapid Kill of viruses, bacteria, and molds

• Active against biofilms

• Works on Fabrics