how textiles give protection against microorganism.

1. By:
Dr. Mumtaz Hasan Malik
TE – 576

2. 1. Introduction
2. Transmission of Bacteria and Liquid Through Fabrics
3. Fabrics for Gowns and Drapes
4. Gown Design
5. Performance Standards for Gowns and Drapes
6. Unresolved Issues

3. *Concern about transference of microorganisms in hospitals and
operating theatres
*Increase in the presence of resistant pathogens is also a concern
*Effective barriers reduce or eliminate the risk of infection
*Gowns and drapes are used to protect the healthcare worker and the patient
*Suitable protective textiles against microorganisms are under investigation
since 1952
*Textiles must be a suitable barrier against bacterial and fluids found in
operating rooms
*Bacterial and viral diseases are spread through airborne and blood born
pathways

4. *Surgical clothing is a medical device worn during surgical procedures
to protect the patient and operating room personnel from transfer of
microorganisms, body fluids and particulate materials
*Infection and surgical site infections cause death and add cost to healthcare
*Primary routes of contact between healthcare worker and microorganisms are:
*Contact transmission
*Respiratory droplets
*Airborne droplet nuclei
*Suitability of a fabric as a barrier to the transmission of pathogens and the
mechanisms of their transference are required to be examined
*Physical, mechanical and comfort properties of such fabrics are also important
in this regard

5. *Fabrics are not solid but porous structures
*Their physical and chemical properties and the shape and surface
morphology of bacteria and their carriers contribute to control the
movement of microorganisms through fabrics
*Bacteria are transported by other particles and liquids
*In medical procedures fluids like blood, perspiration and alcohol can
act as carriers transporting the bacteria through the fabric
*Particles such as shedding skin, cells, dust, lint and respiratory
droplets produced by cough, sneezing or talking are likely carrier
particles of bacteria

6. *Therefore, interaction of the carrier and the barrier and the
effectiveness of the barrier are necessary to consider
*Liquid and bacteria can be drawn through by capillary action
enhanced by wicking
*In fabrics, fibres and yarns are surrounded with interstices forming
capillaries
*Pressure drop across the curved surfaces cause the rise or depression
of a liquid in a capillary

7. *Capillary action is governed by:
*Characteristics of the fluids (viscosity surface tension and density)
*Nature of surface (surface energy and surface morphology)
*Interaction of the fluid with the surface (inter facial tension and contact
angle)
*Pore characteristics (size, volume, geometry and orientation)
* Combination of these factors determine the movement of a liquid
through the fabric
*Various systems are used to measure the contact angle between liquids and
fabrics

8. *Surface tensions of water and saline solutions ~70-72 dyne/cm, blood
~42 dyne/cm and isopropyl alcohol ~22 dyne/cm
*Fabrics used as barrier in healthcare facilities must repel liquids of
lower surface tensions
*Fabrics must act as filter medium, where pore size, geometry and
volume are critical in transmitting the liquid
*Liquid carriers also act as lubricant and/or energy provider
*Therefore smaller pore size does not ensure the trapping of the
particles within the fabric structures

9. *Bacteria ~1-5µm, viuruses ~30nm (HIV virus ~13nm), fungi >5µm
*Shape of microorganisms also influence their movement through the
fabric structures

10. *Surgical gowns and drapes are produced from a variety of fabrics and a wide
range of fibres
*The products are commonly classified as “disposable” or “reusable”
*Disposable products are most commonly nonwovens spun
bonded/meltblown/spun bonded polypropylene or spunlaced woodpulp/
polyesters
*Reusable gowns are laundered and sterilized after each use
*Common fabric for reusable gowns are woven or trilaminate construction
*Plan weave of cotton/polyester blends or polyester and trilaminate fabrics are
composed of a microporous membrane between layers or woven polyester or
knitted polyester

11. *To enhance barrier effectiveness woven and nonwoven products are
sometimes reinforced with additional layers
*Barrier effectiveness is influenced by repellency, pore size, thread count,
thickness and hydrostatic resistance
*Final fabric properties are influenced by
Fibres: Absorbency, surface morphology, length, fineness
Yarns: Type, twist, hairiness
Fabric Construction: Pore size and geometry, surface characteristics
Finishes: Repellent finishes: flourocarbon-based finishes,
Antibacterial Finishes: bactericides, fungicides, disinfectants, antiseptics,
chemotherapeutic agents and antibiotics

12. *Gram-positive bacteria is more sensitive to antibiotics
*Broad spectrum antibiotics are more effective
*Antimicrobial compounds include alocohal, oxidizing agents heavy
metals, acids,,aldehydes, surfactants and antibiotics

13. *Apart from selecting the appropriate fabrics for reduced transmission
of bacteria, the design of gown is also important for the proper
working of healthcare workers
*Gowns must allow adequate mobility and should be designed to fit a
diversity of body shapes and sizes
*Gowns must be easy to put on and remove without contaminating the
worker and workplace
*Gown must be comfortable
*Gowns must be reinforced in those areas that received the high levels
of bloods exposure

14. *AATCC 42-2000: Water Resistance Impact Penetration Test
*AATCC 127-2000: Water Resistance: Hydrostatic Pressure Test
*ASTM 1670-03: Standard Test Method for Resistance of Materials
Used in Protective Clothing to Penetration by Synthetic Blood
*ASTM F 1671-03: Standard Test Method for Resistance of Materials
Used in Protective Clothing to Penetration by Blood-Borne Pathogens
Using Phi-X174 Bacteriophage Penetration as a Test System
Bacteriophage Penetration Resistance

15. *Level 1: Surgical gowns, other protective apparel, surgical drapes and
drape accessories that demonstrate the ability to resist liquid penetration
when tested with AATCC 42(< 4.5g)
*Level 2&3: Describe surgical gowns other protective apparel, surgical
drapes and drape accessories that demonstrate the ability to resist liquid
penetration in AATCC 42 and AATCC 127, with level 3 requiring higher
values than level 2 as follows
Level 2 AATCC 127 (>20cm) and AATCC 42(<1.0g)
Level 3 AATCC 127 (>30cm) and AATCC 42(<1.0g)

16. *Level 4: it has two components one for surgical gowns and protevtive
apparel that have the ability to resist liquid and viral penetration in test
ASTM F 1671; the second for drape and drape accessories with the ability
to resist liquid penetration in test ASTM 1671

17. *What is the optimum interstitial dimension which prevents the
passage of microorganism yet allows the passage moisture vapor ?
*Do fabric surface treatments have a more important effect?
*Do we really understand the humidity dependent transmission?
*Do recently developed semipermeable fabrics sufficiently resist the
passage of microorganism?
*Are antimicrobial treatments of fabric suitable for the future?
*Do the so far developed test standards/methods fulfill all performance
requirements?
*Which product should be given preference: disposable or reusable ?

18. *With numerous mechanisms to trap potentially harmful particles, our
bodies are adept at protecting us from certain hazardous contaminants. As
the size of the contaminant decreases however, so too does the body's
ability to defend itself against them. Typically, particles smaller than five
microns pass the body's defence mechanisms and enter the lungs or
bloodstream
*This is where the importance of air filters comes to the fore. By removing
the smaller, most harmful particles from the air around the body, filters
offer the defence that the body can't provide

19. *In spite of this, just because the body can protect us from particles greater
than five microns, does not necessarily mean they should. In some cases,
such particles can pose a risk to both short and long-term health and, if
filters are employed to remove these larger particles, our bodies are free to
get on with more critical areas of protection

21. Straining - The most basic form of filtration, the particle is larger than the
space between two fibres, and so, cannot follow the airstream through and
is captured

22. Impingement - The mechanism by which large, high density particles are captured
is called impingement. As the particulate laden air passes through the filter media,
the air tends to pass around the fibres. Inertia of the particulate causes it to separate
from the airstream to collide with the fibres to which they become attached.

23. Diffusion - occurs specifically with the very small particles which follow irregular
patterns, in a manner similar to gases, and not necessarily following the airstream.
This irregular pattern is known as Brownian motion and increases the particles
chance of capture through contact with the fibres.
.

24. Interception - Only found in synthetic filters, interception occurs when a particle
follows the airstream but still attaches itself to the fibre as it passes around it. This is
due to the electrostatics force attracting the particle towards the fibre where it is
retained.