Biological Hazards in Medical Laboratories

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Biological Hazards in Medical Laboratories
2
What You Will Learn

• This module gives an overview of how bacteria
  and viruses can cause injury, illness, disease,
  and even death to medical laboratory workers.

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Bacteria Exposure

• Center for Disease Control (CDC) data indicates
  these bacteria have a high chance of exposure
  potential
• Mycobacterium tuberculosis
• Bacillus anthracis
• Bordetella pertussis
• Brucella sp.
• Neisseria meningitidis

Many labs also culture other types of dangerous
bacteria.
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Bacteria Exposure

• In the lab bacteria can become airborne by
• Mouth pipetting
• Manipulation of cultures
• Centrifuge, test tube fractures/cracks

5
Bacteria Exposure

• Tuberculosis
• Present in sputum, gastric lavage, CSF, urine and
  lesions of persons with active disease (not
  latent)
• Bacilli survive in heat-fixed smears
• Transmitted via airborne droplet from infected
  persons respiration, in preparation of frozen
  sections and in preparation of liquid cultures.

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Bacteria Exposure

• Tuberculosis
• Surveillance PPD skin testing based on
  laboratorys risk level
• Prior vaccination with BCG not considered when
  interpreting PPD skin test. It is impossible to
  differentiate between BCG mediated response and
  latent infection.

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Bacteria Exposure

• Tuberculosis
• 90 of all persons infected with TB will never
  develop active TB disease
• TB infected or exposed people are NOT contagious
• Only contagious if they have ACTIVE TB disease

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Bacteria Exposure

• Anthrax
• Present in blood, skin lesion exudate, CSF,
  pleural fluid, rarely in urine and feces
• Aerosolized during handling
• Direct and indirect contact of intact or broken
  skin with cultures and contaminated lab surfaces
• Requires prompt diagnosis
• Vaccine is available

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Bacteria Exposure

• Anthrax Story
• Lab in Texas was processing environmental samples
  for anthrax in support of CDC bioterrorism
  investigation.
• A worker had cut his face shaving. The next day,
  he was moving vials containing aliquots of
  confirmed anthrax from the biological safety
  cabinet to a freezer in the next room. The worker
  did not use gloves. He washed his hands after
  handling the vials.
• Within one day, his facial cut worsened on day
  5, he was admitted to the hospital and treated
  for cutaneous anthrax.
• Most likely source was the surface of the vials.
• No workers in the lab were immunized
• against anthrax.

From April 5, 2002 MMWR (Morbidity and Mortality
Weekly Report from CDC)
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Bacteria Exposure

• Pertussis (whooping cough)
• Hazard is aerosol generation during the
  manipulation of cultures
• Incidence on the rise
• May be mild or classic in adults
• Most lab cases related to research labs

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Bacteria Exposure

• Pertussis (Whooping cough)
• No pertussis containing vaccine is currently
  licensed for persons 7 years of age or older
• If exposed, antibiotics used as prevention

12
Bacteria Exposure

• Brucellosis
• The most commonly reported lab-associated
  bacterial infection
• Present in blood, CSF, semen and occasionally
  urine of infected persons
• Aerosols generated during lab procedures
• Vaccine for cattle only, no vaccine for humans

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Bacteria Exposure

• N. meningitis
• Present in pharyngeal exudates, synovial fluid,
  urine, feces, CSF
• Aerosols from laboratory procedures on isolates
• Vaccine available
• Post-exposure antibiotics
• Rifampin or ciprofloxacin given orally or
• Ceftriaxone given IM

The use of post-exposure antibiotics have
prevented outbreaks.
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Bacteria Exposure

• Meningitis Story
• Two microbiologists contracted meningitis, both
  died.
• 1 3 days before symptoms, the patient had
  prepared a gram stain from the blood culture of a
  patient who was subsequently shown to have
  meningococcal disease. The microbiologist had
  also handled and subcultured agar plates w/ CSF.
  At this lab, aspiration from blood culture
  bottles was performed at an open lab bench.
• 2 Microbiologist who worked at state public
  health lab and worked on several n meningitides
  isolates. Performed slide agglutination tests.
  Used BioSafety Level 2 precautions.
• In 15 years, 16 cases of meningitis in lab
  personnel,
• 50 were fatal.

From MMWR 2/22/02
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Other Pathogen Exposure

• Fungal agents
• Coccidiomycosis and Histoplasma
• Hazard because spores are lt5 microns and can be
  aerosolized and inhaled
• Spores resistant to drying and remain viable for
  long periods

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Other Pathogen Exposure

• Parasitic agents
• Intestinal (giardia, toxoplasma), tissue and
  organs (trichinosis), blood (malaria)
• Ingestion is primary hazard
• Also can enter body through breaks in the skin

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Other Pathogen Exposure

• Prions
• Transmissible spongiform encephalopathies
• Present in CNS
• Resistant to conventional inactivation
• No known treatment

Diseases include Creutzfeld-Jakob Disease and
similar diseases. First US case of new variant
CJD has been reported in Florida. These diseases
are not communicable via contact or aerosol
between persons. No reported lab cases yet,
however incubation can be as long as 10 years.
Highest concentration in CNS and its coverings
thus potential exposure is during autopsy or
post-mortem examinations. Highly resistant to
conventional inactivation procedures including
irradiation, boiling, dry heat and chemicals.
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Other Pathogen Exposure

• Rickettsial Agents
• Coxiella burnetti Q fever
• High risk of lab infection
• Aerosol and parenteral exposures
• Rickettsia species
• Typhus, reported in 57 lab-associated cases
• Rocky mountain spotted fever, in 1976, 63 lab
  cases were reported, 11 were fatal
• Aerosols and parenteral inoculation

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Virus Exposure

• Some viruses are transmitted via aerosols such
  as
• Hantavirus
• Human herpes viruses
• Influenza
• Pox viruses

Hantavirus 4 persons known to have contracted
hantavirus infection while handling infected
rodents in the lab setting. Herpes viruses are
ubiquitous primarily an opportunistic
infection. Rarely, cytomegalovirus or
Epstein-Barr may be transmitted in the lab. No
documentation that influenza has been contracted
in the lab as it also is ubiquitous in season.
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Virus Exposure

• Hepatitis A and E
• Fecally transmitted
• We hear about it in the news when infected
  restaurant workers may expose a community
• Although high virus titers may be present in
  blood during the incubation period, lab
  transmission not reported

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Virus Exposure Blood/Body Fluids

• Some pathogens are transmitted through
  microorganisms contained in blood and other body
  fluids.
• Examples are
• Hepatitis B Virus (HBV)
• Hepatitis C Virus (HCV)
• Hepatitis D Virus (HDV)
• Human Immunodeficiency Virus (HIV)

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Virus Exposure Blood/Body Fluids

• Blood includes
• Human blood
• Human blood components, such as packed cells and
  plasma
• Products made from human blood, such as
• Clotting agents for hemophilia
• Immune globulins including Rh factor immune
  globulins

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Virus Exposure Blood/Body Fluids

• Potentially infectious body fluids include

• Semen
• Vaginal secretions
• Cerebrospinal fluid
• Synovial fluid
• Pleural fluid

• Pericardial fluid
• Peritoneal fluid
• Amniotic fluid
• Saliva in dental procedures

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Virus Exposure Blood/Body Fluids

• Other pathogens also transmitted through blood
  include
• Malaria
• Syphilis
• Brucellosis
• Leptospirosis
• Cruetzfeldt-Jakob Disease
• Some fungi and ricketsii

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Virus Exposure Blood/Body Fluids

• Hepatitis B, C, and D
• Very infectious
• Causes liver inflammation and/or damage - mild to
  fatal
• Can live in a dry environment gt 7 days, such as
  on countertop
• Highest risk of transmission through hollow bore
  needle stick

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Virus Exposure Blood/Body Fluids

• Hepatitis B, C, and D
• Hepatitis B, active and passive vaccines
  available
• Hepatitis C, no vaccine available
• Hepatitis D, no vaccine available, however
  immunization against hepatitis B also protects
  against hepatitis D

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Virus Exposure Blood/Body Fluids

• Human Immunodeficiency Virus (HIV)
• Attacks the human immune system
• Can live in a dry environment for only a few
  hours
• No vaccine available
• Antiviral post-exposure prophylaxis effective in
  reducing risk

Reference MMWR June 29, 2001/50(RR11)1-42
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HIV Virus Exposure Routes

• Parenteral
• Needlestick
• Scalpel/glass cut
• Mucous membrane
• Mouth pipetting
• Eating, drinking in lab area
• Not wearing appropriate PPE
• Non-intact skin
• Unguarded splash
• Contact with contaminated surfaces
• Not covering skin breaks

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HIV Virus Exposure

• HIV Story
• The CDC reports as of December 2001, 51 of
  the 57 cases of occupationally acquired HIV
  infection involved sharps injuries of which
  nearly half involved needles used in phlebotomy
  or blood sampling from a vascular line, with
  vacuum- tube device needles accounting for the
  largest number of these injuries.
• Other sharps injuries included broken glass from
  blood collection tubes and a needle for
  cleaning/dislodging debris in laboratory
  equipment.

Reference Infection Control Hospital
Epidemiology, Feb 2003
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Biosafety Guidelines

• The Centers for Disease Control (CDC) has
  guidelines to describe combinations of
• Laboratory Practices and Techniques
• Standard Practices
• Special Practices
• Safety Equipment
• Laboratory Facilities

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Biosafety Guidelines

• These guidelines are called
• CDC Biosafety in Medical and Biomedical
  Laboratories (BMBL)
• The BMBL guidelines describe four laboratory
  hazard levels or Biosafety Levels (BSL)

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Biosafety Guidelines

• Biosafety Levels 1-4 provide
• Increasing levels of personnel and
• environmental protection
• Guidelines for working safely in
• microbiological and biomedical
• laboratories

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Biosafety Levels (BSL)

• The Four Biosafety Levels are
• BSL1 - agents not known to cause disease (B.
  subtilis, E. coli).
• BSL2 - agents associated with human disease
  (hepatitis B, Salmonellae, Toxoplasma)
• BSL3 - indigenous/exotic agents associated
• with human disease and with potential for
• aerosol transmission (M. tuberculosis, C.
  burnetii).
• BSL4 - dangerous/exotic agents of life
• threatening nature (Marbug and Ebola virus).

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WISHA Rules

• Occupational Exposure to Bloodborne Pathogens
  WAC 296-823
• This rule provides requirements to protect
  employees from exposure to blood or other
  potentially infectious materials, that may
  contain bloodborne pathogens.
• The rule covers anticipated exposure, even if no
  actual incidents have occurred.

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Other WISHA Rules Directives

• Protect Employees from Biological Agents
  296-800-11045
• Personal Protective Equipment, 296-800-160
• WRD 11.35 Tuberculosis

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• Thank you for taking the time to learn about
  safety and health and how to prevent future
  injuries and illnesses.