Title: Biological Hazards in Medical Laboratories
1Biological Hazards in Medical Laboratories
2What 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.
3Bacteria 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.
4Bacteria Exposure
- In the lab bacteria can become airborne by
- Mouth pipetting
- Manipulation of cultures
- Centrifuge, test tube fractures/cracks
5Bacteria 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. -
6Bacteria 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.
7Bacteria 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
8Bacteria 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
9Bacteria 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)
10Bacteria 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
11Bacteria 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
12Bacteria 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
13Bacteria 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.
14Bacteria 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
15Other 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
16Other 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
17Other 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.
18Other 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
19Virus 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.
20Virus 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
21Virus 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)
22Virus 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
23Virus 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
24Virus Exposure Blood/Body Fluids
- Other pathogens also transmitted through blood
include - Malaria
- Syphilis
- Brucellosis
- Leptospirosis
- Cruetzfeldt-Jakob Disease
- Some fungi and ricketsii
25Virus 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
26Virus 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
27Virus 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
28HIV 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
29HIV 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
30Biosafety 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
-
31Biosafety 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)
32Biosafety Guidelines
- Biosafety Levels 1-4 provide
- Increasing levels of personnel and
- environmental protection
- Guidelines for working safely in
- microbiological and biomedical
- laboratories
33Biosafety 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).
34WISHA 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.
35Other 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.