BIOSAFTEY AND INFECTION CONTROL

Q1: Write on the dangerous of infection in microbiology lab workers.

Those who work in microbiology laboratories are exposed to danger of infection either from clinical specimens or laboratory cultures. Both of them put the employee at risk of potential contact with infectious agents through:

(1) Mucous membranes (rubbing the nose or eyes with contaminated hands),(2) Inhalation of aerosols of microorganisms, (3) Accidental ingestion (putting pens or fingers into the mouth), or (4) Needle sticks.

Biologic hazards in the microbiology laboratory come from two major sources:

(A) Processing of the patient specimens:

Laboratory personnel are at risk of exposure to blood-borne pathogens related to injuries from contaminated sharps, splashes to the eyes or mouth, and unprotected exposure of blood/body fluids onto non-intact skin. Beside blood and serum, all human excretions, secretions, tissues, similar materials from animals and eggs, and even uninoculated cell cultures should be regarded as potentially infectious.

Hepatitis B virus can be transmitted to laboratory workers through needle stick injuries. The CDC estimates that approximately 12.000 health care workers become accidentally infected with this blood-borne pathogen annually. Human immunodeficiency virus (HIV) is another blood-borne pathogen that may be transmitted to laboratory personnel from contaminated specimens through a needle stick injury or another percutaneous route.

(B) Handling of the actively growing cultures of microorganisms.

Concentrated cultures of certain microorganisms in the microbiology laboratory offer opportunity for laboratory-acquired infection when activities such as subculturing blood culture bottles, mixing, vortexing, and centrifugation. Examples of microorganisms transmitted to laboratory personnel from these activities include N. meningitides, M. tuberculosis, Brucella spp, B. anthracis and Yersinia pestis.

Mycobacterium tuberculosis:

It has long been known to cause tuberculosis in laboratory workers exposed to aerosols created in processing sputum samples. A laboratory accident involving a spill of active M. tuberculosis, which could easily aerosolize through the ventilation system, is every microbiologist’s nightmare.

Brucella:

Brucella spp. and Francisella tularensis are other infectious agents that can be transmitted through inhalation of an aerosol created during the processing or handling of specimens (e.g., blood, which may harbour these organisms) or cultures of the organism.

Coccidioides:

Coccidioides immitis, the most infectious of all the fungi, can infect several people in a room if culture plates on which the organism is growing are not sealed with tape or are open in the absence of a biosafety hood.

Q2: Write on the safety programs in microbiology lab workers.

Safety in the microbiology laboratory can be best achieved by a combination of (1) knowledge and (2) common sense. Knowing current safety regulations, incorporating them into safety procedures manuals, and teaching the procedures to each employee through in-service education should be the duties of an assigned safety officer.

Laboratories dealing with infectious materials (clinical samples, bacteria, viruses and fungi) are required to follow certain Infection Control Guidelines in order to reduce inherent risks during manipulation of patient specimens, of cultures, of contaminated sharps, and of diagnostic equipment.

Those who work in the laboratory need to use Standard Precautions to minimize the risk of laboratory-acquired infections and to promote a safe environment for all personnel in the laboratory and elsewhere.

Laboratory design, proper equipment, and personnel knowledge about safety issues can all contribute to protection of personnel. The comprehensive safety program for the microbiology laboratory needs to fulfill the following:

Address biologic hazards.

Describe the safe handling, storage, and disposal of chemicals and radioactive substances.

Clearly outline the laboratory or hospital policies for correct procedures in the event of fire, natural disasters, and even bomb threats.

Teach correct techniques for lifting and moving heavy objects and patients.

This safety program needs to be ongoing and consistent with current federal and state regulations.

Most important, it must be presented in a way that encourages employees to incorporate the safety practices into their daily routines and take responsibility for keeping the work environment safe.

Q3: Write on how to collect specimen.

In collecting specimens take care to avoid both unnecessary contamination of the material and self-infection by spillage, aerosol or splashing into the eye, by contamination of broken skin, or by needle-stick injury. Transfer specimens safely into the appropriate robust container.

Take care to avoid contaminating the outside of the container and close it rightly to avoid leakage in transit.

Always label containers immediately after the specimen has been introduced and, where required, affix special labels, such as HEPATITIS RISK or HIGH RISK, as when a specimen may contain typhoid bacilli or HIV. Ensure that the containers remain upright to avoid spillage.

Q4: Write on how to receive specimen.

Specimens must be received in a dedicated reception area in the laboratory which must not be in a clerical office or public corridor. Reception staff who unpack containers and request forms must wear gowns and gloves, for the hazard associated with individual specimens is not known.

If there has been leakage of a specimen due to lose capping or breakage, the safety officer must decide whether the specimen is to be discarded or whether the difficulty of obtaining a replacement (e.g. one of CSF) is such that the leaking container should be taken to a safety cabinet and the specimen transferred to a fresh container.

Q5: Enumerate routes of infection (write on one of them in details).

Routes of infection could be:

(1) Inoculation,(2) Ingestion, or(3) Inhalation

Ingestion: Ingestion is a route of infection that takes place through the mouth.

It may take place by:

1. Licking, sucking or accidental swallowing of infective material, or 2. Splashing it on to the lips, or3. Touching the mouth with contaminated fingers, pen or pencils, or 4. Licking labels contaminated by the fingers, or 5. Using the mouth in pipetting infected fluids.

Mouth pipetting is particularly dangerous, for even if the mouth-piece contains a filter, its end is liable to be contaminated by the fingers. Laboratory rules must forbid mouth pipetting; there are adequate pieces of equipment which make it unnecessary.

Eating, drinking, smoking and applying cosmetics in the laboratory must be forbidden.

Hands should be washed on completion of work and also on leaving the laboratory.

Q6: Enumerate hazard procedures (write on one of them in details).

Hazardous procedures include the following:

Usage of syringes and needles Pipetting Inoculating loop Petri-dishes Shaking or mixing Centrifugation Freeze-drying Stoppering tubes Dealing with Microbiologically safety cabinets Animal procedures Transport of specimen and its disposal

Shaking / mixing and centrifugation:

Shaking produces an aerosol, even in a closed container, and the aerosol may be released on opening the container soon afterwards. Gross contamination can occur from spillage or breakage.

Also during centrifugation, vibration can generate aerosol within the container. Careless loading or unloading, breakage during centrifugation or premature opening after breakage can lead to gross dissemination.

Q7: Enumerate hazard groups (write on one of them in details).

There are four groups:

A- GROUP 1: Organisms most unlikely to cause human disease.

B- GROUP 2: Organisms that rarely cause human disease or infection. They may be a hazard to laboratory workers, but unlikely to spread in the community. Effective prophylaxis or treatment is usually available. Most pathogens fall into this group.

C- GROUP 3: Organisms that may cause severe human disease and present a serious hazard to laboratory workers. They may pose a risk of spread in the community, but there is usually effective prophylaxis or treatment.

D- GROUP 4: Organisms that cause severe human disease and pose a serious risk to laboratory workers. They may pose a high risk of spread in the community and there is usually no effective prophylaxis or treatment.

Q8: Write on standard precautions during work.

In 1987, the CDC published guidelines known as universal precautions, to reduce the risk of HBV transmission in clinical laboratories and blood banks. In 1996, these safety recommendations became known as standard precautions.

These precautions require that blood and body fluids from every patient be treated as potentially infectious. The essentials of Standard Precautions and safe laboratory work practices as follows:

Do not eat, drink, smoke, or apply cosmetics (including lip balm). Do not insert or remove contact lenses. Do not bite nails or chew on pens. Do not mouth-pipette. Limit access to the laboratory to trained personnel only. Assume all patients are infectious for HIV or other blood-borne pathogens. Use appropriate barrier precautions to prevent skin and mucous membrane

exposure, including wearing gloves at all times and masks, goggles, gowns, or aprons if there is a risk of splashes or droplet formation.

Thoroughly wash hands and other skin surfaces after gloves are removed and immediately after any contamination.

Take special care to avoid injuries with sharp objects such as needles and scalpels.

The CDC’s Standard Precautions should be followed for handling blood and body fluids, including all secretions and excretions (e.g., serum, semen, all sterile body fluids, saliva from dental procedures, and vaginal secretions) submitted to the microbiology laboratory. Standard Precautions do not apply to feces, nasal secretions, saliva (except in dental procedures), sputum, sweat, tears, urine, or vomitus unless they are grossly bloody.

Q9: Write on the types of cabinets and their benefits (one of them in details), and which one is used in the Microbiology lab?

Three classes of cabinet are defined in the British standard; the class required being determined by the degree of hazard and protection:

Class I cabinets: These cabinets are open-fronted. The exhaust air from the cabinet is filtered by a high-efficiency particulate air (HEPA) filter. The Class I biosafety cabinet will provide personnel and environmental protection. Procedures such as shaking, mixing or ultrasonic disruption of any material likely to contain dangerous organisms should be done in a class 1 or class 2 cabinet.

Class II cabinets: These are vertical laminar-flow biological cabinets which are also open-fronted. Class II cabinet provides a HEPA-filtered, re-circulated mass airflow within the work space. Some of the air is also exhausted from the cabinet, and filtered by HEPA filters. Thus, the Class II biosafety cabinet will provide personnel, environment and product protection. Class 2 cabinets are preferred for work with uninoculated cell cultures and other materials requiring protection from air-borne contamination.

Class III cabinet: Class III cabinet is a totally enclosed ventilated cabinet of gas-tight construction. Operations within the Class III cabinet are conducted through attached rubber gloves. The air pressure in the cabinet being kept less than that in the room. The cabinet exhaust air is filtered by two HEPA filters, installed in series, before discharge outside of the facility.

The use of a Class II cabinet in the microbiological laboratory offers the additional capability and advantage of protecting materials contained within it from extraneous airborne contaminants. This capability is provided by the HEPA-filtered, recirculated mass airflow within the workspace.

Q10: How to make protection to staff? (Mention one of them in details).

Protection of the lab staff against microbial infections is achieved through (1) immunizing them against tuberculosis, rubella, Hepatitis B...etc, and through (2) training the staff to follow the laboratory safety precautions.

Immunization as a protection to the lab staff:

Immunization is an important precaution against laboratory infection.

HBV immunization must be offered to all laboratory staff likely to come into contact with specimens or other materials that may contain virus.

For all new female staff of child-bearing age, they should have their rubella immunity status checked and, if found to have an inadequate level of antibodies, they should be offered immunization.

Vaccination against other infections that may be acquired in the laboratory, e.g. typhoid, poliomyelitis, diphtheria, cholera, anthrax and rabies, should be considered for staff working with the organisms or likely to come into contact with materials containing them.

Q11: How to dispose jars, sharp materials, and pipettes?

All materials contaminated with potentially infectious agents must be decontaminated before disposal:

Infectious wastes may be decontaminated by use of an autoclave, or incinerator.

Pipettes, swabs, and other glass objects should be placed into rigid cardboard containers before disposal.

Broken glass is placed in thick boxes lined with plastic biohazard bags; when full, the box is incinerated or autoclaved.

Sharp objects, including scalpels and needles, are placed in sharps containers, which are autoclaved or incinerated when full.

For jars, clean and disinfect them carefully, preferably by heat. When the material of the jar will allow it, do so by autoclaving. Refill with fresh disinfectant diluted accurately to the correct concentration, i.e. weak (1%) or strong (10%) hypochlorite as appropriate, or phenolic disinfectant at 1-2% concentration. Use hypochlorite for viruses and phenolic for other purposes, the higher concentration (2%) of phenolic where tubercle bacilli may be present. Jars must contain enough disinfectant to cover all that is to be put in them. Carefully discard the used pipettes, slides and infective fluids into the disinfectant in such a way as to avoid splashing.