Instructions In Microbiology
Section A:
Microbiology laboratory should provide information on specific procedures for collection and transport of specimens.
Guidelines | |
1 | Put on personal protective equipment and perform hand hygiene before collecting and transporting specimens. |
2 | Whenever possible, collect specimens in the acute stage of the illness and prior to administration of antimicrobial agents (and/or before switching antimicrobial drug regimen). |
3 | Collect the specimens at optimal times (for example, for TB: early morning sputum for AFB microcopy and culture; or during febrile episode for blood cultures). Collect the specimens from the actual site of infection or where the microorganisms are most likely to be found. |
4 | Use Standard Precautions for collecting and handling all specimens to protect staff from blood and body fluids (e.g., through hand hygiene, personal protective equipment, injection safety, and proper waste disposal). |
5 | Avoid contamination from surrounding tissues or secretions. Use sterile equipment and aseptic techniques to collect specimens to prevent introduction of microorganisms during invasive procedures. |
6 | Use appropriate collection devices, transport media, and sterile, leak- proof specimen containers. |
7 | Properly label each specimen with the patient’s name and identification. Fill in the test request form. Provide the source of the specimen (e.g., wound, skin). |
8 | If the specimen is collected through intact skin, prepare the skin using iodine solution (e.g., povidoneiodine) or a chlorhexidine-alcohol combination. Allow a drying time of 2 minutes without wiping or blowing to maximize antiseptic effect. |
9 | Collect a sufficient quantity of material for the specimen. |
10 | Provide clear instructions to patients if they are collecting their own specimens (e.g., clean catch urine or stool, collection of sputum). |
11 | Minimize transport time, preferably within 2 hours of collection. |
12 | Always transport specimens in a leak-proof container clearly labeled as a |
biohazard. | |
13 | Maintain an appropriate temperature between collection of specimens and delivery to the laboratory. Check if the specimens should or should not be transported on ice. |
14 | Remove personal protective equipment and perform hand hygiene after collecting and transporting specimens. |
Section B:
Procedure for Specific Specimen Collection: Guidance for Routine Blood Culture Collection:
Age | Bottle(s) | Total Blood Volume | Blood Culture Set |
≥15 years old | 1 Aerobic (8 to 10 mL) 1 Anaerobic (8 to 10 mL) | 16 to 20 mL | 1 Set = 1 Aerobic Bottle and 1 Anaerobic Bottle |
<15 years old | 2 Pediatric (1 to 4 mL) | 2 to 8 mL | 1 Set = 2 Pediatric Bottles |
Neonates | 1 Pediatric (0.1 to 1 mL) | 0.1 to 1 mL | 1 Set = 1 Pediatric Bottle |
The next picture show Aerobic and Anaerobic blood culture bottles
Guidance for Upper Respiratory Tract collection:
This section describes procedures for obtaining culture specimens from the nasopharyngeal area and the throat.
A nasopharyngeal culture is obtained by inserting a thin sterile swab gently through the nose to touch the pharynx; gently rotate and remove.
A throat culture is obtained by introducing a sterile swab into the mouth. Use a tongue blade to avoid contaminating the specimen with oral secretions. Firmly swab both tonsillar fossae, posterior pharynx, and any inflamed or ulcerated areas.
Guidance for Lower Respiratory Tract collection:
This section discusses sputum cultures, including such alternatives as induced sputum, tracheal aspiration, and bronchial washings.
Rinsing the mouth with saline or water (but not mouthwash) may reduce contamination with normal oropharyngeal flora.
Encourage deep cough with expectoration of the sputum into a sterile specimen collection cup that is labeled with the patient's name.
Do not send saliva (spit) for culture.
When the patient is unable to cough productively, notify the physician. An alternative method may be ordered, such as:
Induced sputum. This is done by a respiratory therapist on the orders of the physician. Involuntary deep coughing is induced by irritation.
Tracheal aspiration. The trachea is gently irritated with a small lumen suction catheter, which causes deep, productive coughing. Also, the specimen may be aspirated with a syringe.
Bronchial washings. These are done by the physician in the operating room at the time of bronchoscopic examination. Sputum following bronchoscopy can be very productive for the recovery of mycobacteria.
A small amount of sputum is all that is required, but it must be sputum and not oral secretions.
Three sputa collected on consecutive days is recommended for the recovery of mycobacteria.
The next picture show sputum culture plate with positive penicillium.
Guidance for wound exudate collection:
Gently cleanse the area, using dry, sterile gauze to remove any contaminants.
Using a sterile bacterial culture collection system, introduce deeply enough to obtain a moist specimen; replace the swab in the container. Do not break the container.
Store at room temperature.
The next picture show obtaining a wound culture by swap.
Guidance for Urine Culture collection:
Explain carefully to patients the mechanics of midstream collection and the importance of collecting an uncontaminated specimen. Teach them how to handle the specimen container to keep it sterile.
A clean-catch specimen is necessary to confirm the presence or absence of infecting organisms in urine. The specimen must be free of any contaminating matter that might be present on the genital organs; therefore, patients should be urged to follow the steps outlined below.
Instructions for the Female Patient.
If you are menstruating, first insert a fresh tampon or use cotton to stop the flow. Separate the skin folds around the urinary opening.
Wash the urinary opening and its surroundings from front to back with a sterile antiseptic pad.
Begin urinating into the toilet, making sure you keep the skin fold apart with the fingers of one hand.
Wait until the urine stream is well established before moving the container into the path of the stream to catch the rest of the urine. Do not touch the container to the genital area.
Instructions for the Male Patient.
Wash the end of the penis well with soapy water. Let it dry.
Begin urinating into the toilet. Wait until the urine stream is well-established before moving the container into the path of the stream to catch the rest of the urine. Do not touch the container to the genital area.
Cleansing agents, such as soap or detergent, must be rinsed away from the urethral area before the specimen is collected.
A urine specimen from a catheterized patient is obtained by using a sterile 21- to 23-gauge needle and a 3-mL syringe. Prepare an area on the distal end of the rubber catheter with an antiseptic sponge. Insert the needle at a 45° angle, pointed toward the drainage tubing. If urine is not obtained, try lifting the catheter tubing carefully. If necessary, kink the tubing three inches from the catheter and hold in place with a rubber band until urine is visible.
Urine for culture must be transferred to a urine transport tube that contains preservative immediately after collection.
Guidance for stool for culture collection:
A small amount is all that is required, about the size of a walnut. If several different types of cultures are requested, submit a walnut-sized sample for each. Place the specimen in stool culture transport medium (C&S vial).
When stool specimens are not readily obtainable, rectal swabs are acceptable; however, it must be indicated whether the specimen is a stool or a rectal swab. Place the swab in stool culture transport medium (C&S vial).
Section C:
Instrument used in microbiology laboratory :
Autoclave:
Autoclaves are mostly used for the sterilization of medical or laboratory equipment with the capacity of sterilizing a large number of materials at once.
They are commonly used for the preparation of culture media during laboratory applications
Bunsen burner:
It is commonly used for processes like sterilization, combustion, and heating. In medical or microbiology laboratories, it is commonly used for micro-loop sterilization.
Colony counter:
A colony counter is primarily used for counting the number of colonies present on a culture plate to estimate the concentration of microorganisms in liquid culture.
Deep freezer:
A deep freeze can be used for the preservation of different things used in the laboratories for a very long period of time. Deep freezers are used in laboratories to store and preserve medical equipment, food items, blood samples, medicines, and injections, etc. for a more extended period of time.
Homogenizer
A homogenizer is primarily used to disrupt cells to acquire cell organelles for different microbiological processes.
It is used in the preparation step before the extraction and purification of different macromolecules like proteins, nucleic acids, and lipids.
Hot plate
In a laboratory, hot plates are used to heat glassware and its components.
They are used over water baths as water baths might be hazardous in case of any spills or overheating.
Hot air oven
A hot air oven can be used to sterilize materials like glassware, metal equipment, powders, etc.
It allows for the destruction of microorganisms as well as bacterial spores.
Laminar air flow
Laminar Hood is commonly used to conduct processes that are sensitive to contamination.
It is used for experiments related to plant tissue culture and for the experiments of genetic transformation.
Magnetic stirrer
It is usually used for mixing various liquid components in a mixture in a chemical or microbiology laboratory.
This device is used in place of other stirrers as it is noise-free and because the size of the stir bar is so tiny, there is less chance of contamination.
Microscope
Based on the type of microscopes, different microscopes are used for different purposes.
They are primarily used for the observation of minute particles which cannot be observed with naked eyes.
Vortexer
Vortex mixer is mostly used for the mixing of various sample fluids in the sample tubes and also allows for the homogenization of cells and cell organelles
