Biological Hazards in Medical and Research Laboratories

October, 2010

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

What You Will Learn

Bacteria Exposure

The Centers for Disease Control (CDC) data indicates these bacteria have a high exposure potential in labs:

– Mycobacterium tuberculosis

– Bacillus anthracis

– Bordetella pertussis

– Brucella sp.

– Neisseria meningitis

Many labs also culture other types of dangerous bacteria.

Bacteria Exposure

In the lab bacteria can become airborne by:

– Removing vacutainer caps– Manipulation of cultures– Centrifuge, test tube fractures/cracks

Bacteria Exposure - Tuberculosis

– Present in sputum, gastric fluid, CSF, urine and lesions of persons with active disease (not latent)

– Bacilli survive in heat-fixed smears

– Transmitted via airborne droplet – from an infected person’s respiration, in preparation of frozen sections and in preparation of liquid cultures.

Tuberculosis

– 90% of all persons infected with TB will never develop active TB

– TB infected or exposed people are NOT contagious

– Only contagious if they have ACTIVE TB disease

Source: CDC

- Surveillance: PPD skin testing or blood assay based on laboratory’s 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.

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

Gram-positive anthrax bacteria (purple rods) in cerebrospinal fluid sample

An Anthrax Infection Incident• 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)

Skin anthrax- source: CDC

Pertussis (whooping cough):

– Hazard is aerosol generation during culture manipulation

– Incidence on the rise – see the latest report

– May be mild or classic in adults

– Most lab cases in research labs

Source: CDC

- A pertussis vaccine is now available for adults

Brucellosis– One of the most commonly reported

lab-associated bacterial infection

– Present in blood, CSF, semen and occasionally urine of infected persons

– Transmitted through aerosols generating procedures

- No vaccine for humans, treatment is with antibiotics Reported cases of brucellosis - 2007

Source: CDC

CDC recommendations for brucellosis lab exposure

N. Meningitis

– Present in pharyngeal exudates, synovial fluid, urine, feces, CSF

– Aerosols from laboratory procedures on isolates

– Vaccine is available and recommended for lab workers routinely exposed.

– Post-exposure antibioticso Rifampin or ciprofloxacin given orally; or

o Ceftriaxone given IM

The use of post-exposure antibiotics have prevented outbreaks.

Link to CDC webpage on meningitis

N. Meningitis bacteria

Meningitis Exposure Incidents

• 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 sub-cultured 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, there were 16 cases of meningitis in lab personnel, of which 50% were fatal.

From MMWR 2/22/02

Other Possible Pathogen Exposures

• Fungal agents:

– Coccidioimycosis and Histoplasmosis

– Hazard because spores are <5 microns and can be aerosolized and inhaled

– Spores resistant to drying and remain viable for long periods

– Both can be treated with antifungal drugs

Link to NIOSH document: “Histoplasmosis – protecting workers at risk”

Link to CDC webpage on coccidioidomycosis (Valley Fever)

Link to CDC webpage on histoplasmosis

Other Possible Pathogen Exposure

• Parasitic agents:

– Intestinal (giardia, toxoplasmosis), tissue and organs (trichinosis), blood (malaria)

– Ingestion is primary hazard

– Also can enter body through breaks in the skin

CDC webpage on parasitic diseases

CDC webpage in giardia

Other Possible Pathogen ExposurePrions:– Transmissible spongiform encephalopathies– Present in CNS of animals– Resistant to conventional inactivation– No known treatment– Includes Creutzfeldt-Jakob disease

Link to CDC Prion Diseases webpage

This tissue slide shows sponge-like lesions in the brain tissue of a classic CJD patient. This lesion is typical of many prion diseases.

Other Possible Pathogen Exposures

• Rickettsial Agents:– Coxiella burnetti – Q fever

o High risk of lab infectiono Aerosol and parenteral exposures

– Rickettsia species

o Typhus, reported in 57 lab-associated caseso Rocky mountain spotted fever, in 1976, 63 lab

cases were reported, 11 were fatalo Aerosols and parenteral inoculation

CDC webpage on Q Fever CDC webpage on Rickettsia

Virus ExposureSome viruses are transmitted via aerosols such as:

– Hantavirus – lab infections have occurred during rodent handling

– Human herpes viruses

– Influenza

– Various pox viruses

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.

CDC – lab management of agents associated with hantavirus – interim biosafety guidelines -1994

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)

Link to “Exposure to Blood brochure

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

• Potentially infectious body fluids include:

Virus Exposure – Blood/Body Fluids

Semen

Vaginal secretions

Cerebrospinal fluid

Synovial fluid

Pleural fluid

Pericardial fluid

Peritoneal fluid

Amniotic fluid

Saliva in dental procedures

Virus Exposure – Blood/Body Fluids

• Other pathogens that can also be transmitted through blood include:

– Malaria

– Syphilis

– Brucellosis

– Leptospirosis

– Cruetzfeldt-Jakob Disease

– Some fungi and ricketsii

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

Hepatitis A virus

Virus Exposure – Blood/Body Fluids

Hepatitis B, C, and D

– Transmitted via blood or other body fluids

– Causes liver inflammation and/or damage - mild to fatal

– Can live in a dry environment > 7 days, such as on countertop

– Highest risk of transmission through hollow bore needle stick

Healthy human liver

Hepatitis C liver

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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

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

HIV - seen as small spheres on the surface of white blood cells

HIV Virus Exposure Routes

Parenteral– Needlestick– Scalpel/glass cut

• Mucous membrane

– Mouth pipetting– Eating, drinking in lab area– Not wearing appropriate PPE

– Non-intact skino Unguarded splasho Contact with contaminated surfaceso Not covering skin breaks

HIV Virus Exposure

Occupationally acquired HIV :

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: Surveillance of Occupationally Acquired HIV/AIDS in Healthcare Personnel – December, 2006

Lab Practices & Biosafety Guidelines

• The Centers for Disease Control (CDC) has guidelines to describe combinations of:

– Laboratory Practices and Techniques

o Standard Practices

o Special Practices

– Safety Equipment

– Laboratory Facilities

CDC Laboratory Guidelines and Standards webpage

CDC Biosafety Webpage – includes a biosecurity online training course

CDC Biosafety Guidelines• These guidelines are called:

Biosafety in Medical and Biomedical Laboratories (BMBL - 5th edition)*

• The guidelines describe four laboratory hazard levels or Biosafety Levels (BSL)

* Some of the information in this module is derived from this document

Biosafety GuidelinesBiosafety Levels 1- 4 provide:

– Increasing levels of personnel and environmental protection

– Guidelines for working safely in microbiological and biomedical laboratories

Class I Biosafety Cabinet(from CDC publication – Selection, Installation & Use of Biosafety Cabinets)

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).

DOSH Rules related to biological hazards

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.

Link to Online Training course on Bloodborne Pathogens

Other Related DOSH Rules & Directives

• Protect Employees from Biological Agents 296-800-11045 – refers to CDC guidelines

• Personal Protective Equipment, 296-800-160

• Tuberculosis - WRD 11.35