Laboratory Biosafety Levels

1
Laboratory Biosafety Levels
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Goals

• Define barriers and procedures used by
  laboratories to protect workers and others from
  infection
• Describe the four biosafety levels and the
  protective measures used by each type of
  laboratory when handling infectious materials
• Provide examples of the types of biological
  agents handled in each type of laboratory
• Describe typical places where each type of
  laboratory can be found in the US

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Why is Biosafety Important?

• Laboratorians recognize hazards of processing
  infectious agents
• Guidelines developed to protect workers in
  microbiological and medical labs through
  engineering controls, management policies, work
  practices

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Biosafety Levels

• Precautions so people researching or trying to
  identify organisms do not become infected
• While handling or testing clinical specimens,
  workers could accidentally infect themselves or
  coworkers
• Labs must adhere to very specific safety
  regulations to work with organisms that pose a
  threat to human health

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Biosafety Levels

• Regulations outline precautions, special
  practices, decontamination procedures
• Labs divided into 4 biosafety levels protective
  practices increase with each
• Biosafety Level 1 labs - work with least
  dangerous agents, require fewest precautions
• Biosafety Level 4 labs - have strictest methods
  because dealing with agents that are most
  dangerous to human health

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About this Information

• Information summarized here should not be used to
  establish laboratory safety protocols
• Complete information and recommendations can be
  found in Biosafety in Microbiological and
  Biomedical Laboratories 5th Edition at
  http//www.cdc.gov/od/ohs/biosfty/bmbl4/
  bmbl4s6.htm

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Barriers

• Primary barriers physical barriers or personal
  protective equipment between lab worker and
  pathogen
• Gloves, masks, special breathing apparatuses
• Secondary barriers structural aspects of the
  laboratory that make working environment safer
  against infection
• Sinks for handwashing, special containment areas,
  special air ventilation patterns 

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Universal Precautions

• Universal precautions developed to protect health
  professionals
• Most often apply in a clinical setting
• May also be important for field epidemiology
  practices during an outbreak investigation (e.g.,
  collecting lab specimens)
• Include hand hygiene, gloves, gown, masks, eye
  protection, face shields, safe injection
  practices
• Require that all equipment or contaminated items
  are handled to prevent transmission of infectious
  agents
• Special circumstances may require additional
  precautions
• Protective clothing, special site decontamination

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Biosafety Level 1 (BSL-1)

• Agents not known to cause disease in healthy
  adults
• Some organisms may cause disease in
  immunocompromised individuals

• Agents include Bacillus subtilis, Naegleria
  gruberi, infectious canine hepatitis virus,
  non-pathogenic E. coli species
• (transmission electron micrograph of E. coli)

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Biosafety Level 1 (BSL-1)

• Standard practices required
• frequent handwashing
• door that can be kept closed when working
• limits on access to the lab space when working
• no smoking, eating, drinking, storage of food in
  laboratory
• care to minimize splashes and actions that may
  create aerosols (tiny droplets)
• decontamination of work surfaces after every use
  after any spills
• (continued on next slide)

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Biosafety Level 1 (BSL-1)

• Standard practices (continued)
• decontamination of laboratory wastes
• use of mechanical pipettes only (no mouth
  pipetting)
• "sharps" precautions, including special
  containers for disposing of needles and other
  sharp objects
• maintenance of insect/rodent control program
• use of personal protective equipment (lab coats,
  latex gloves, eye protection or face shields)
• Open bench top sink for hand washing

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Biosafety Level 2 (BSL-2)

• Agents associated with human disease
• Generally required for any human-derived blood,
  bodily fluids, tissues in which infectious agent
  may be unknown

• Agents include measles virus, Salmonella species,
  pathogenic Toxoplasma, Clostridium botulinum,
  hepatitis B virus
• (transmission electron micrograph of hepatitis B
  virus)

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Biosafety Level 2 (BSL-2)

• Primary hazards
• accidental needle sticks
• exposure to eyes and nose (mucous membranes)
• ingestion of infectious materials
• Agents do not cause lethal infections, are not
  transmissible via airborne route
• (do not cause infection if tiny droplets become
  airborne and are inhaled, which might occur if
  the material were spattered)
• Agents are pathogens for which immunization or
  antibiotic treatment is available
• Extreme care should be taken with contaminated
  needles and sharp lab instruments

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Biosafety Level 2 (BSL-2)

•  Standard practices include BSL-1 plus
• policies to restrict access to lab
• biohazard warning signs posted outside lab
• surveillance of laboratory personnel with
  appropriate immunizations offered
• biosafety manual with definitions of needed waste
  decontamination or medical surveillance policies
  
• supervisory staff who have experience working
  with infectious agents and specific training for
  laboratory personnel in handling these agents

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Biosafety Level 2 (BSL-2)

• Primary barriers biosafety cabinets or other
  approved containment devices
• Personal protective equipment lab coats, gloves,
  face protection as needed
• Protective clothing removed when personnel leave
  laboratory area
• Cabinets thoroughly decontaminated daily and
  monitored for radiation for personal protection
• Secondary barriers BSL-1 barriers plus autoclave
  for glassware

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Biosafety Level 2 (BSL-2)

• Example of biosafety sign posted outside lab
  working with infectious agents
• Labs biosafety level
• Infectious agents under study
• Contact information for responsible person and 2
  emergency contacts

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Biosafety Level 3 (BSL-3)

• Agents with potential for respiratory
  transmission, may cause serious and potentially
  lethal infection
• May be studied at BSL-2 for diagnosis 

• Agents include Mycobacterium tuberculosis, St.
  Louis encephalitis virus, Francisella tularensis,
  Coxiella burnetii
• (F. tularensis under direct fluorescent antibody
  stain)

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Biosafety Level 3 (BSL-3)

• Primary hazards needle sticks, ingestion,
  exposure to infectious aerosols
• For example
• Public health surveillance for West Nile virus
  includes testing birds
• In August 2002, state laboratory worker cut
  finger while dissecting bird 4 days later, had
  symptoms of fever, myalgia, recurring sweats, hot
  flashes
• Worker and bird both diagnosed with West Nile
• 2 other lab-acquired cases in 2002

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Biosafety Level 3 (BSL-3)

• Tularemia common source of laboratory-acquired
  infection
• infections occur while handling infected animals
  or experimenting with cultures
• Laboratory-acquired infections known to occur but
  not reportable before 9/11/2001
• Tularemia now classified as potential
  biological weapon

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Biosafety Level 3 (BSL-3)

•  Standard practices include BSL-2 plus
• strictly controlled access to the lab
• specific training for lab personnel in handling
  potentially lethal agents
• decontaminating all waste
• changing contaminated protective lab clothing,
  decontaminating lab clothing before laundering
• institutional policies regarding specimen
  collection and storage from workers to establish
  exposure

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Biosafety Level 3 (BSL-3)

• Primary barriers
• Similar to BSL-2 personal protective equipment
• Respiratory equipment if risk of infection
  through inhalation
• Secondary barriers
• All BSL-2 barriers
• Corridors separated from direct access to lab
• Access through self-closing double doors
• Air handling systems to ensure negative air flow
  (air flows into the lab)
• Air pumped into lab not re-circulated in
  building

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Biosafety Level 4 (BSL-4)

• Dangerous and exotic agents with high risk of
  life-threatening disease, aerosol-transmitted
• Related agents with unknown risk of transmission

• Agents (all viruses) include Marburg virus, Ebola
  virus, viruses that cause Congo-Crimean
  hemorrhagic fever, Lassa fever
• (transmission electron micrograph of Ebola virus)

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Biosafety Level 4 (BSL-4)

• Primary hazards
• respiratory exposure to infectious aerosols
• mucous membrane exposure to infectious droplets
• accidental sticks with needles or other sharp
  objects contaminated with infectious material
• For example
• In late 1960s, 25 laboratory-acquired Marburg
  infections, including 5 deaths
• Workers studying infected monkeys from Uganda
• First documented naturally-occurring human case
  occurred in 1975

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Biosafety Level 4 (BSL-4)

• Personnel must receive specialized training in
  handling extremely dangerous infectious agents,
  containment equipment and functions
• Access to lab is restricted immunocompromised
  persons are never allowed to enter the lab
•  Standard practices include BSL-3 plus
• strictly controlled access to the laboratory
• changing clothing before entering and exiting lab
  (showering upon exiting recommended)
• decontaminating all material exiting facility

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Biosafety Level 4 (BSL-4)

• Primary barriers
• Biosafety cabinets used at other biosafety levels
• Full-body, air-supplied, positive pressure
  personnel suit
• Secondary barriers
• All physical barriers at BSL-3
• isolated zone or a separate building
• dedicated supply and exhaust, vacuum,
  decontamination systems
• a recommended absence of windows
  (or sealed and resistant to breakage)

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Laboratory Locations

• BSL-1 high schools, community colleges,
  municipal drinking water treatment facilities
• BSL-2 local health departments, universities,
  state laboratories, private laboratories
  (hospitals, health care systems), industrial
  laboratories (clinical diagnostic companies)
• BSL-3 state health departments, universities,
  private companies, industry, federal government
  (NIH, CDC)
• BSL-4 only 15 facilities in the US
• 9 federal (CDC, NIH), 4 university (Georgia State
  University, University of Texas Medical Branch),
  1 state, 1 private
• Renovations underway at several labs, new
  facilities proposed at additional sites

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Summary

• Laboratorians have long recognized hazards of
  processing infectious agents
• Biosafety guidelines developed to protect workers
  in microbiological and medical labs through a
  combination of safeguards including engineering
  controls, management policies and work practices.
• Issue described differences between biosafety
  levels
• Help you understand process labs may have to
  undertake to identify microorganism, why every
  lab cannot test for every organism

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References

1. US Department of Health and Human Services,
   Centers for Disease Control and Prevention and
   National Institutes of Health. Biosafety in
   Microbiological and Biomedical Laboratories. 5th
   ed. Washington, DC US Government Printing
   Office 2007. http//www.cdc.gov/od/ohs/
   biosfty/bmbl5/bmbl5toc.htm. Accessed February 6,
   2008.
2. Clemson University Environmental Health and
   Safety. Biological Safety online training.
   http//ehs.clemson.edu/training/biosafety/index.ht
   ml. Accessed February 6, 2008.
3. Centers for Disease Control and Prevention.
   Laboratory-Acquired West Nile Virus Infections
   United States, 2002. MMWR Morb Mort Wkly Rep.
   2002 511133-1135. http//www.cdc.gov/mmwr/previ
   ew/ mmwrhtml/mm5150a2.htm. Accessed February 6,
   2008.
4. United States Government Accountability Office.
   High-Containment Biosafety Laboratories
   Preliminary Observations on the Oversight of the
   Proliferation of BSL-3 and BSL-4 Laboratories in
   the United States. Publication GAO-08-108T.
   http//www.gao.gov/docsearch/ abstract.php?rptnoG
   AO-08-108T. Published October 4, 2007.