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Biological Hazards in Medical Laboratories

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Title: Biological Hazards in Medical Laboratories


1
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.

3
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.
4
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.

6
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.

7
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

8
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

9
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)
10
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

11
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

13
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.
14
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
15
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

16
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

17
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.
18
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

19
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.
20
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

21
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)

22
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

23
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

24
Virus Exposure Blood/Body Fluids
  • Other pathogens also transmitted through blood
    include
  • Malaria
  • Syphilis
  • Brucellosis
  • Leptospirosis
  • Cruetzfeldt-Jakob Disease
  • Some fungi and ricketsii

25
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

26
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

27
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
28
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

29
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
30
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

31
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)

32
Biosafety Guidelines
  • Biosafety Levels 1-4 provide
  • Increasing levels of personnel and
  • environmental protection
  • Guidelines for working safely in
  • microbiological and biomedical
  • laboratories

33
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).

34
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.

35
Other WISHA Rules Directives
  • Protect Employees from Biological Agents
    296-800-11045
  • Personal Protective Equipment, 296-800-160
  • WRD 11.35 Tuberculosis

36
  • Thank you for taking the time to learn about
    safety and health and how to prevent future
    injuries and illnesses.
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