Specimen collection and preservation

Specimen collection and preservation

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  WINTER GE RALCONCE T F NE P S OR SP CIM N E E Template SPECIMEN COL E ION , H L CT ANDLING OF AND SP CIM N P E E ROCE SSING By Serena Lobo DOS in Microbiology Mysore University
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  INTRODUCTION Laboratoryinvestigations use scientific methods to help us arrive rapidly at a diagnosis of an infectious disease. Once the causative agent for a particular infection has been identified, appropriate and rational therapy can be instituted. Before requesting for laboratory investigations, the clinician should have arrived at a provisional diagnosis of the probable cause of an infection, based on accurate and detailed history taking and careful physical examination. Anyone connected with medical care, whether a doctor, nurse or a laboratory technician may collect a specimen. Hence all medical personnel should have a clear understanding of the principles behind the collection of appropriate specimen for microbiological examination.
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  GE RAL CONSIDEAT NE R IONS R GAR E DING COL E ION L CT OF SP CIM N E E ῼCollect culture specimens before antibiotic therapy. ῼThe specimen must be representative of the infection with as little contamination from normal flora as possible. ῼUtilize appropriate collection devices, use sterile equipment and aseptic technique to collect specimens. ῼCollect an adequate amount of specimen. ῼCollect specimens in sturdy, sterile, leak proof containers. ῼClear and specific instructions on proper collection techniques must be given to patients when they must collect their own specimens.
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  ῼThe specimen mustbe transported promptly and maintained in a manner that allows survival of fastidious organisms and prevents overgrowth by more hardy organisms. ῼSpecimens that are collected in syringes are best maintained by dead-capping the syringe, expelling excess air, and transporting to the laboratory in the syringe. ῼA fluid or tissue specimen is generally a more desirable specimen than a swab.
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  DOCUMENTATION WINTER Each tube or container with obtained specimen must be Template provided with a stick - on label with written name of the patient, date of taking the specimen and exact description of the source of the specimen. Other details to be noted are: ♣ Name and address of the patient, his/her birth number, his/her health insurance number. ♣Number of days from the onset of symptoms of disease. ♣ Clinical diagnosis. ♣Exact description of the obtained specimen, date (hour) of taking it and sending to the lab. ♣Requested examination. ♣The name and stamp of the ordering doctor, his/her identity number and address of the health facility .
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  TRANSPORTATION OF SPECIMEN •Specimenshould be packed well and labeled ‘HAZARDOUS’ on the packing. •The specimen must be delivered to the laboratory as soon as possible •To overcome any delay and drawbacks due to delay in reaching the microbiology department, the following methods may be used. ☺Transport media ☺Refrigeration ☺Freezing
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  TRANSPORT MEDIA oTransport mediais a medium for transporting clinical specimen to the laboratory for examination for examination. oTransport media should fulfill the following criteria: ♠Temporary storage of specimen being transported to the laboratory for cultivation. ♠Maintain the viability of the organisms in the specimen without altering their concentration. ♠Contains only buffers and salts. ♠Lack of carbon, nitrogen, organic growth factors so as to prevent microbial multiplication. ♠Transport media used in the isolation of anaerobes must be free of molecular oxygen. Examples :Thioglycolate broth for strict anaerobes. Venkat-Ramakrishnan medium for Vibrio cholarae.
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  CONTAINERS FOR COLLECTINGSPECIMEN
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  TECHNIQUESOF SPECIMEN COLLECTION FROMSKIN: WINTER Template ☻The area of the skin from which specimen is collected is first cleaned using soap and water. ☻Swabs are firmly rubbed over the affected part of the skin and sent at once to the laboratory for processing. ☻Only swabs which have been moisturized in sterile broth or saline should be used. ☻If a viral infection is suspected, crusts, scabs or vesicle fluids are collected in capillary tubes. ☻If a fungal lesion is suspected, infected hairs and nails as well as scrapings from the affected part of the skin may be collected.
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  F OM TE UP E RE IR ORY T ACT R H P R SP AT R Oral cavity : Swabs are rubbed firmly over the ulcerated or patch like lesions. Anterior nares: If pus is present is present, collect it on the swabs. If no pus is present, moisten the swabs and then swab the anterior nares. Troat: The mouth is held wide open and the tongue is depressed. Swabs are firmly rubbed over the tonsils and pharyngeal mucosa.
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  Nasopharynx : A pernasalswab is used. This is made from fairly flexible wire which is bent at one end and is covered with sterile cotton at this end. The swab is carefully passed through the cavity till it impinges on the nasopharynx and then firmly rubbed over the area. Epiglottis : Swabs are firmly rubbed over the inflamed and ulcerated areas. Before collecting the swabs precautions should be taken to maintain the airways in case a laryngeal spasm suddenly occurs. Ideally the swabs should be taken by an ENT surgeon. Paranasal sinuses: If pus is present in these sinuses , it is collected on swabs or aspirated with a syringe and needle.
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  FROM LOWER RESPIRATORYTRACT ᵜCommonly only sputum is collected. This should be coughed up from far down the bronchial tree and expectorated immediately. It should not be mixed with saliva or other oropharyngeal secretions. ᵜAn even better specimens material that is aspirated directly from the bronchi or trachea. This is collected by using a flexible fibreoptic bronchoscope. ᵜAn alternative is to collect bronchial washings. ᵜThese procedures should be conducted by an experienced pulmonologist or cardio thoracic surgeon.
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  FROM THE GASTROINTESTINALTRACT WINTER Feces is collected on a sterile wide mouthed , leak Template proof container preferably provided with a small spoon to transfer material to any other container. If feces are semi solid , a small quantity is sufficient: if liquid, it should fill a third of the specimen jar. Fresh feces may be collected by inserting a short catheter into the rectum. A rectal swab can be collected as an alternative : this is gently inserted into the rectum and turned clockwise and anti clockwise ensuring the rectal mucosa is firmly rubbed.
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  FROM URINARY TRACT Contamination of urine by bacteria colonizing the distal parts of the urethra and the perenium is prevented by clean catch technique. Here the periurethral area is cleaned twice with soap and water. The urethra is flushed by voiding the first portion of the urine , which is discarded. The subsequent mid stream urine is collected directly in a sterile container and is used for culture and colony counting. It is essential for cultural purposes that urine be processed within one hour of collection or stored in a refrigerator at 40 C till it can be cultured.
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  FROM THE GENITALTRACT In women: The best specimen is a cervical swab. A sterile bivalve speculum is moistened with warm water and inserted into the vagina. The cervical mucus plug is removed with a cotton ball and forceps: the external surface of the cervix is then cleaned with a large cotton swab. In men: If the patient has purulent urethral exudates, culture is not necessary. A Gram stained direct smear is enough for clinical diagnosis of Gonorrhea if intracellular gram negative diplococcic are seen. In men, uncentifuged first voided urine may be cultured for N. gonorrhea .
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  FROM CENTRAL NERVOUSSYSTEM ᴪThe Cerebro Spinal Fluid is usually collected from lumbar puncture. ᴪThe dural sheath is pierced by a needle and CSF is allowed to drip from it into a sterile container. ᴪIt is essential to avoid introducing contaminating organisms into the subdural space or the specimen. ᴪTherefore the procedure should be viewed as a minor surgical operation. ᴪThe technique should be vigourously aseptic.
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  WINTER FROM THE BLOODSTREAM Blood is collected by strict aseptic technique and care Template should be taken to avoid introducing organisms into the blood stream as well as prevent contamination of the specimen. The vein from which the blood is to be taken should be clearly seen and the skin overlying the vein is vigorously wiped with 70% alcohol. Once the area is dry, the specimen is collected using a perfectly dry, sterile syringe and needle. After this, the area is cleaned with 70% alcohol and finally wiped with povidine-iodine in alcohol.
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  FROM PLEURAL ANDPERITONEAL CAVITIES ۞. A sample of pleural fluid is collected by a doctor with a syringe and needle using a procedure called thoracentesis. ۞The health care provider will clean the skin around the insertion site and drape the area. ۞A local anesthetic is injected into the skin. ۞The thoracentesis needle is inserted above the rib into the pocket of fluid. As fluid drains into a collection bottle, many people cough a bit as the lung reexpands to fill the space where fluid had been. ۞This sensation normally lasts for a few hours after the test is completed.
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  FROM THE CONJUNCTIVA,LID MARGINS, CORNEA AND INTRAOCULAR STRUCTURES Material from the lid margin is collected by firmly rubbing a pre moisturized swab from the Inferior lid margin to superior lid margin. The swab is inoculated into appropriate culture media. Any visible purulent conjunctival discharge is collected on a swab and inoculated at once. If pus discharge is not present, smears can be made and culture media is inoculated with material taken directly from the conjunctival surface by a sterile bacteriological loop (made of platinum and not nichrome). FROM THE EAR A swab can be used to collect material from the external ear. The swab on the wire is inserted into the external auditory canal with a twisting motion to collect a secretion from it.
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  CRITERIA FOR REJECTIONOF SPECIMEN WINTER Criteria should be developed by a laboratory on the Template basis of which the processing of a specimen may not be done by the laboratory. The following are some examples: § Missing or inadequate identification. § Insufficient quantity. § Specimen collected in an inappropriate container. § Contamination suspected. § Inappropriate transport or storage. § Unknown time delay. § Haemolysed blood sample.
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  PROCESSING OF SPECIMEN ¶ Once the appropriate specimen has been collected, they are processed as speedily as possible to ensure that organisms that the organisms do not die before being transferred to the culture media, and that the reports are available at the earliest. ¶ Generally material is placed on slides and stained appropriately, and then examined under the microscope. ¶ If bacteria and fungi are detected, specific therapy can be started at once. Material is also inoculated onto appropriate culture media.
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  CONCLUSION Specimen collection isan essential prerequisite that the laboratory must be given sufficient clinical information to guide the microbiologist in selection of the suitable media and appropriate techniques. Also, it is important for the clinician to appreciate the limitations and potentials of the microbiological laboratory and to realize that a negative report does not necessarily invalidate the diagnosis. It is essential that a close cooperation and frequent consultation among the clinician, nurse and microbiologist are the rule rather than exception.