AEROSOL TRANSMISSIBLE DISEASESCMU OFFICE OF LAB AND FIELD SAFETY

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TRAINING OVERVIEW

Define laboratory acquired infections

Identify the occupational risks and hazards of working with

aerosol transmissible pathogens (ATPs)

Identify requirements for handling of aerosol transmissible

pathogens with specific laboratory equipment

Identify proper steps to take in the event of an incident

involving aerosol transmissible pathogens

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LABORATORY-ACQUIRED INFECTIONS

Laboratory-acquired infections (LAIs) are defined as all

infections acquired through laboratory or laboratory-related

activities regardless of whether they are symptomatic or

asymptomatic in nature. Ex. Mtb

Check out the ABSA International LAI Database @

https://my.absa.org/LAI

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POSSIBLE ROUTES OF EXPOSURE FOR

LABORATORY-ACQUIRED INFECTIONS

Contact between mucous membranes and

contaminated material

• Contaminated surfaces or hands, direct splashes/droplets

Ingestion

• Aspiration through a pipette, smoking or eating in lab

• Ingestion following application of cosmetics and lipstick in

the lab

Percutaneous inoculation

• Needle and syringe, cuts or abrasions from contaminated

items, animal bites

Inhalation

• Aerosols-most relevant to this training! 4

AEROSOLS

An aerosol is a suspension of fine solid particles or liquid droplets, in air or another gas

An aerosol is the most common source of LAIs, WHY?

Not as easily detected as a needle stick, animal bite, or splash

Multiple infections from single exposure incident

Aerosols are generated by many common laboratory techniques, examples include: sonicating, vortexing, pipetting

Any time energy is applied to a microbial culture, aerosols may be generated!

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AEROSOL TRANSMISSIBLE DISEASES

Aerosol transmissible diseases

(ATDs) are caused by pathogenic

microbes called aerosol

transmissible pathogens (ATPs)

These microbes can be spread when

an infected person coughs, sneezes or

laughs

The microbes are able to remain

suspended in the air and may travel

several feet before settling

The primary method of contracting an

ATD is through inhalation of these

microbes

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EXAMPLES OF AEROSOL TRANSMISSIBLE

PATHOGENS

Examples include:

Mycobacterium tuberculosis

Brucella spp.

Bordetella pertussis

Measles virus

Rabies virus

Varicella zoster virus

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MYCOBACTERIUM TUBERCULOSIS

Tuberculosis (TB) is one of the most widely

recognized ATDs

Not everyone that contracts TB becomes ill

~5% of infections active TB

~95% of infections latent TB (~10%

reactivate; cannot spread to others)

When TB does cause illness, it can infect any part

of the body

Active TB is called TB disease

Most common site for TB disease is the lungsFilm chest x-ray show interstitial infiltrate both

lungs due to Mycobacterium tuberculosis infection

(Pulmonary Tuberculosis). Photo Credit:

stockdevil/iStock/Getty Images8

SYMPTOMS AND TREATMENT OF TB DISEASE

Individuals with latent TB do not display symptoms

Symptoms of TB disease vary depending on the location of the bacteria

Symptoms of TB disease in the lungs are:

Left untreated, TB can spread beyond the lungs and cause death

Most forms of TB (including lab strains) are diagnosable and treatable, you’ll

be work with the Mtb strain H37Rv9

Severe cough lasting longer

than three weeksChest pain

Coughing up blood or sputum

Weakness

Weight loss Loss of appetite Fever

TB – LAB RISKS

Primary route of transmission is inhalation of TB containing

aerosols

Secondary routes of transmission (uncommon in laboratory)

include ingestion and direct inoculation

TB-causing bacteria can remain viable for extended periods

in the environment

Infectious dose is estimated to be < 10 bacilli by inhalation

for humans

In animal studies, infectious doses range from 1 organism

to 1,000 organisms, depending on the susceptibility of the

species10

TB – LAB RISKS

Risk is elevated in labs that manipulate cultures

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IDENTIFYING REQUIREMENTS FOR PROPER

HANDLING OF AEROSOL TRANSMISSIBLE

PATHOGENS WITH SPECIFIC LABORATORY

EQUIPMENT

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REDUCING THE RISK OF LABORATORY-

ACQUIRED INFECTIONS

Factors contributing to

the reduction in LAIs

may include

improvements in

containment equipment,

engineering controls,

and an increased

emphasis on safety

training

0

200

400

600

800

1000

1200

1930-1950 1951-1978 1979-2004

Fungi

Rickettsia

Viruses

Bacteria

Parasites

Source: Harding, A.L., Brandt Byers, K.. Epidemiology of laboratory–associated infections. In Fleming, D.O. and Hunt.

D.L. Biological Safety: Principles and Practices. 4th edition. Washington, DC: ASM Press, 2006; 53-77.

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Symptomatic LAIs by Time Period and Agent Category

REDUCTION OF LAB RISKS

Elements that must be in place to reduce risks of TB exposures

include:

1. Careful risk assessment of all procedures, equipment and techniques

2. Properly maintained and certified/calibrated/monitored equipment

3. Appropriate laboratory design and facilities

4. Job appropriate medical surveillance program

5. Thorough personnel training program

6. Appropriate waste handling

7. Well reviewed SOPs and safety policies 14

MITIGATION OF BIOAEROSOL EXPOSURE

The use of engineering controls (for example,

biological safety cabinets [BSCs] and room ventilation)

and personal respiratory protection (such as

respirators) can help prevent inhalation of infectious

aerosols

However, the most important consideration in

reducing the risk of infection in the laboratory is to

minimize the production of aerosols

All aerosol generating procedures with open

containers MUST be conducted in the BSC15

MITIGATION OF BIOAEROSOLS – PIPETTING

TECHNIQUES

Pipetting techniques that can reduce the risk of creating bioaerosols when manipulating

TB material include:

Do not forcibly expel infectious liquids from a pipette, stop at the first ‘stop’

Do not forcibly expel air from a pipette into potentially infectious liquids

When using a pipette to add a reagent to a potentially infectious liquid, place the

pipette against the inner wall of the container and gently expel the fluid or hold the

pipette on an angle so that the liquid runs down the side of the tube

Ensure that when expelling liquids, tubes are held on angle so that the liquid runs

down the side of the tube or waste container to minimize any splashes

Only insert the disposable tip of a micropipette into a tube or container, NEVER

submerge the barrel of a micropipette, exceptions include…disinfecting the pipette

Do not mix or suspend infectious materials by repeatedly filling and fully emptying a

pipette, exceptions include…breaking up the Mtb pellet

With serological pipettes don’t draw up into the pipette pump.

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MITIGATION OF BIOAEROSOLS –

CENTRIFUGING TECHNIQUES

When centrifuging a specimen or culture, do so

in a sealed safety cup or sealed rotor to avoid

releasing an aerosol into the centrifuge and

laboratory.

Following centrifuging, place containers inside

the BSC.

Allow aerosols to settle (approx. 10 mins) tube

to.

Always open safety cups or sealed rotors inside

a BSC.

Question: Why is it important to open safety

cups or sealed rotors inside the BSC? If a spill

has occurred in the cups, the BSC will help mitigate

spreading the aerosol.

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MITIGATION OF BIOAEROSOLS –VORTEXING

TECHNIQUES

Never vortex an open tube; always ensure

that screw caps/snap caps are securely

fastened to tubes before vortexing or shaking.

(Do not vortex tubes with cotton plugs or

rubber stoppers.)

Allow aerosols to settle (approx. 10 mins).

Always open vortexed tubes inside a BSC.

Vortexer MUST be placed in the BSC. 18

MITIGATION OF BIOAEROSOLS – REMOVING

TEST TUBE CAPS

Always avoid disrupting a bubble or film in an open culture tube. This may be avoided by replacing the cap, gently tapping the top of the tube, set the tube aside and allowing any generated aerosols to settle before reopening.

Tubes can ONLY be opened in the BSC.

Question: Does opening this type of lid create an aerosol? It is highly likely, remember any time energy is applied to a microbial culture, aerosols may be generated!

Question: How could we reduce or prevent an aerosol from being created? Add a disinfectant-soaked towel to the top of the tube while opening or use a lid opener 19

MITIGATION OF BIOAEROSOLS – BLENDING

AND HOMOGENIZING

Use a laboratory blender/bead beater

with a tight‐fitting gasketed lid and

leak‐proof bearings

Allow aerosols to settle (approx. 10

mins).

Bead beater MUST be used in the BSC.20

MITIGATION OF BIOAEROSOLS – USING BLUNT

NEEDLES

If you need to use a needle, use a blunt needle.

When withdrawing a needle from a stoppered bottle, wrap the needle and bottle cap in a disinfectant‐soaked absorbent.

Use syringes with a Luer lock connector.

Dispose of needles directly into sharps container without further manipulation (needle‐cutting devices release aerosols).

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STEPS TO TAKE IN THE EVENT OF AN

INCIDENT THAT MAY HAVE CREATED AN

AEROSOL

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BIOLOGICAL SPILL INSIDE THE BIOSAFETY

CABINET

A small spill completely contained inside the BSC must be cleaned up immediately,

but does not require any further notification

If the spill is severe and you are unsure about whether to report the spill, notify

the Facility Director and BSO

1. Immediately disinfect the spill area in the BSC

2. Place Kimwipe on the spill to absorb liquid

3. Soak the absorbent material with Vesphene, by slowly pour from the outside of

the cloth to the center

4. Allow at least 10 minutes of contact time before placing absorbent material in

the waste container inside the BSC

5. If the spill occurred on the plastic-backed absorbent towel, slowly pour

Vesphene, to decontaminate, wait 10 mins then discard towel and replace

6. The BSC blower is never turned off and the sash should never be closed during

a spill

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“TYPICAL” BIOLOGICAL SPILL OUTSIDE THE

BIOSAFETY CABINET

1. Do not attempt to clean the spill!

2. Alert all personnel in the BSL-3 Facility to evacuate

3. Decon any PPE thought to be contacted by the spill

Try not to track the spill all over

4. Take note of details of spill

5. Follow the lab exit SOP

6. If the lab and anteroom are maintaining negative pressure, remove the PAPR and remain in the anteroom

7. If the lab or anteroom have pressure failure, keep the PAPR on and remain in the anteroom

Once in the anteroom:

Contact the Facility Director, the Biosafety Officer and OLFS immediately

Place a sign reading “Biohazardous Spill- Do Not Enter” from the spill kit on the inside of the door, facing outward through the window

Stay until contacted personnel arrive

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Note: the following steps are related to “typical” spills outside the BSC without an immediate threat to one’s physical

safety, i.e. like an nearby explosion.

For other spill scenarios outside the BSC refer

to the Emergency Response section of the CMU

BSL-3 Facility Laboratory Manual

IDENTIFYING FACTORS OF A POSSIBLE

EXPOSURE

Incidents involving ATPs are difficult to detect, don’t take it upon yourself to

determine exposure

Notify, consult and discuss the incident with the Facility Director and/or the

Biosafety Officer

If a possible exposure has occurred, immediately report to McLaren Central

Occupational Medicine Program (COMP)

If a possible exposure has occurred you may need to file an incident report.

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WHAT TO DO IN THE EVENT OF AN EXPOSURE

OR POSSIBLE EXPOSURE

Notify the Facility Director and/or the Biosafety Officer

Immediately report to McLaren Central Occupational Medicine Program

(COMP), stating that you are an ATD researcher

If COMP is not open, go to McLaren Central Michigan Fast Track or Emergency

Department

Paid employees-Within 24 hours, notify Workers’ Compensation, (989) 774-

7177

Unpaid workers- Within 24 hours, the Facility Director must submit an

Accidental Personal Injury Report form to Risk Management

Immediate response to exposure will reduce your risk of contracting a

laboratory acquired infection 26

NEAR MISSES

A “near miss” is an event where there was almost a spill or an

exposure but an incident did not actually occur

“Near misses” should always be reported to your supervisor

Question: Why should the ‘near misses’ be reported to

your supervisor? We can learn from these ‘near misses’!

Procedures can be updated to reduce the risk of ‘near misses’.

The Facility Director and Biosafety Officer can be consulted for

assistance in devising safety plans

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QUESTIONS?

Any questions or concerns you have can be directed to the Office of Laboratory

and Field Safety

Contact Information

Office number Cell number

Ben Swarts, PhD Facility Director,

Principal Investigator

989-774-2525 216-308-1248

Tom Schultz Biosafety Officer 989-774-3279 989 330-4660

Jennifer Walton, PhD Director, Office of

Laboratory and Field

Safety

989-774-4189 989-621-0785

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