Safety in the Clinical Microbiology Lab

List 5 routes of infection in the lab and give examples of each

• airborne

  • removing stoppers from specimen or culture tubes

  • centrifugation of unstoppered tubes

  • leakage from specimen containers

• ingestion

  • failure to wash hands

  • eating or drinking in the lab

• direct inoculation

  • needlesticks, broken glass, or open cuts

• mucous membrane contact

  • substance enters through the eyes or nose

• arthropod vectors

  • ticks or mosquitoes can be sources of infection

Which 4 agencies have created regulations for safety in the microbiology laboratory?

OSHA, CDC, CAP, and TJC

Exposure control plans (plans required by OSHA) must include procedures and documentation regarding:

• training and safety education

• universal and standard precautions

• engineering controls

• hazardous materials/waste disposal

• post-exposure procedures

• guidelines to maintain a clean workplace

Training and safety education for lab employees should include:

• new employee orientations

• documented professional development for current employees

• safety manuals

universal precautions

• first introduced by the CDC in 1987

• a set of preventative measures for handling blood and body fluids with visible blood

• meant to reduce the risk of transferring HIV, HBV, and other bloodborne pathogens

standard precautions

• expanded version of universal precautions

• preventative measures applied to all patients to reduce the risk of infection

• all blood, body fluids, secretions, and excretions are considered infectious

Eyewash stations should be in accessible locations no more than __ seconds (or __ feet) away from where hazardous materials are being used.

10, 100

What are engineering controls?

physical changes to a work area or process that protects workers from hazards by removing or blocking them

The CDC has classified microorganisms into various biosafety categories. What are these categories based on? What biosafety level should all clinical labs adhere to?

• based on:

  • number of occupational infections, infectious dose, and route of infection

• all labs should adhere to Biosafety Level 2 guidelines

Describe Biosafety Level 1 and Level 2 for working with infectious agents

• BSL-1

  • organisms not known to cause disease in healthy individuals

  • controlled access to lab, sinks, sharps hazards, PPE, lab bench, and autoclave

  • common microorganisms: B. subtilis and Enterobacter aerogenes

• BSL-2

  • microorganisms have a moderate potential to cause disease

  • requires BSL-1 practices PLUS specific training and a biosafety cabinet

  • common organisms: HBV, HIV, Salmonella, and Shigella

Describe Biosafety Level 3 and Level 4 for working with infectious agents

• BSL-3

  • microbes have potential to cause serious disease

  • requires BSL-2 practices PLUS double-door access, a negative-pressure ventilation system

  • common microorganisms: M. tuberculosis, Brucella, and Rickettsia

• BSL-4

  • level is primarily used in research facilities

  • requires BSL-3 practices PLUS class II biological safety cabinet and decontamination of all personnel and materials before leaving the area

Describe the 3 types of biological safety cabinets

• Class I cabinet

  • ventilated cabinet for personal and environmental protection

  • similar airflow pattern to a fume hood and has a HEPA filter

• Class II cabinet

  • open front with inward flow

  • some air is exhausted and some is filtered and pushed back into the cabinet

• Class III cabinet

  • totally enclosed and ventilated, also negative pressure

  • leak tight with attached rubber gloves

  • materials are sterilized before leaving the cabinet

How is microbiologic waste disposed of in the lab?

• waste must be placed in leak-proof bags (and double-bagged)

• contaminated needles, scalpels, and other related supplies should be placed in puncture-resistant boxes

What is the temperature, pressure, and time required for sterilizing contaminated microbiologic materials and infectious medical waste?

• contaminated microbiologic materials: 121 degrees and 15 psi for one hour

• infectious medical waste: 132 degrees for 30 minutes to an hour

What is the difference between sterilization, disinfection, biocides, and liquid decontaminants?

• sterilization

  • kills all microorganisms, including endospores, via heat, radiation, filtration, or chemically (with ethylene oxide or hydrogen peroxide)

• disinfection

  • destroys most pathogenic microorganisms, but does not eliminate spores

• biocides

  • chemical agents that inactivate microbes

  • bacteriostatic agents inhibit microbial growth and bactericidal agents destroy target organisms

• liquid decontaminants

  • 10% bleach and 70% isopropyl alcohol used for decontaminating lab work benches

What 7 factors impact the effectiveness of disinfectants?

• the surface to be disinfected

• the presence of organic material

  • dirt, blood, mucus, or pus can inactivate the disinfectant

• the amount of time the disinfectant is in contact with the surface

• the type of microbe

• the amount of the microorganisms present on the surface

• the concentration of the disinfectant

• temperature and pH

Fire Safety: What are some sources of ignition in the lab? Where should flammables and combustables be stored?

• sources of ignition

  • open flame, heating elements, spark gaps (can result from static electricity), electrical instrumentation, and flammable liquids

• storage

  • in safety cabinets or other approved containers

  • or in separate rooms away from ignition sources

What are the 5 types of fire extinguishers?

• Type A (water fire extinguisher)

  • used for paper, wood, rubber, cloth, and certain plastics fires

• Type B (CO2 extinguisher)

  • used on extremely flammable liquids or electrical fires

• Type C (dry chemical extinguisher)

  • used for electrical fires (chemicals do not conduct electricity)

• Type D (combustible metal extinguisher)

  • for fires involving combustible metals (sodium or potassium for example)

• Class K

  • used in kitchen fires involving oil or fat

What information can be found in material safety data sheets (MSDS) for chemicals?

• manufacturer information

• physical and chemical characteristics

• hazard data

• precautions for handling

• control measures

• transport and disposal methods

What are the five categories of hazardous chemicals?

• corrosives

  • causes irreversible damage to human skin on contact

• toxic

  • serious biological effects after inhalation, ingestion, or skin contact

• carcinogenic

  • ability of a chemical to induce malignant tumors

• ignitable

  • any chemical that can burn

• explosive

  • reactive and unstable substances that can undergo violent chemical change

permissible exposure limit (PEL)

the legal limit for employee exposure to a chemical or physical agent, expressed in parts per million (ppm)

short-term exposure limit (STEL)

the maximum limits that a worker can be exposed to for up to 15 minutes without danger to health, should be limited to 4 STELs per day