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Specimen collection and preservation


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Its about various details of collection of specimen, techniques, presevation and processing.

Published in: Health & Medicine

Specimen collection and preservation

  1. 1. WINTER GE RAL CONCE T F NE P S OR SP CIM N E E Template SPECIMENCOL E ION , H L CT ANDLING OF AND SP CIM N P E E ROCE SSING By Serena Lobo DOS in Microbiology Mysore University
  2. 2. INTRODUCTION Laboratory investigations use scientific methods to help usarrive rapidly at a diagnosis of an infectious disease. Once the causative agent for a particular infection has beenidentified, appropriate and rational therapy can be instituted. Before requesting for laboratory investigations, the clinicianshould have arrived at a provisional diagnosis of the probablecause of an infection, based on accurate and detailed historytaking 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 clearunderstanding of the principles behind the collection ofappropriate specimen for microbiological examination.
  3. 3. GE RAL CONSIDE AT 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.
  4. 4. ῼThe specimen must be transported promptly andmaintained in a manner that allows survival of fastidiousorganisms and prevents overgrowth by more hardyorganisms.ῼSpecimens that are collected in syringes are bestmaintained by dead-capping the syringe, expellingexcess air, and transporting to the laboratory in thesyringe.ῼA fluid or tissue specimen is generally a more desirablespecimen than a swab.
  5. 5. DOCUMENTATION WINTER Each tube or container with obtained specimen must be Templateprovided with a stick - on label with written name of thepatient, date of taking the specimen and exact description ofthe 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) oftaking it and sending to the lab.♣Requested examination.♣The name and stamp of the ordering doctor, his/her identitynumber and address of the health facility .
  6. 6. TRANSPORTATION OF SPECIMEN•Specimen should be packed well and labeled‘HAZARDOUS’ on the packing.•The specimen must be delivered to the laboratory assoon as possible•To overcome any delay and drawbacks due to delay inreaching the microbiology department, the followingmethods may be used.☺Transport media☺Refrigeration☺Freezing
  7. 7. TRANSPORT MEDIAoTransport media is a medium for transporting clinicalspecimen to the laboratory for examination for examination.oTransport media should fulfill the following criteria:♠Temporary storage of specimen being transported to thelaboratory for cultivation.♠Maintain the viability of the organisms in the specimenwithout altering their concentration.♠Contains only buffers and salts.♠Lack of carbon, nitrogen, organic growth factors so as toprevent microbial multiplication.♠Transport media used in the isolation of anaerobes mustbe free of molecular oxygen.Examples :Thioglycolate broth for strict anaerobes. Venkat-Ramakrishnan medium for Vibrio cholarae.
  9. 9. TECHNIQUESOF SPECIMEN COLLECTIONFROM SKIN: WINTER Template☻The area of the skin from which specimen is collected isfirst cleaned using soap and water.☻Swabs are firmly rubbed over the affected part of theskin and sent at once to the laboratory for processing.☻Only swabs which have been moisturized in sterilebroth or saline should be used.☻If a viral infection is suspected, crusts, scabs or vesiclefluids are collected in capillary tubes.☻If a fungal lesion is suspected, infected hairs and nailsas well as scrapings from the affected part of the skin maybe collected.
  10. 10. F OM T E UP E RE IR ORY T ACT R H P R SP AT ROral cavity : Swabs are rubbed firmly over theulcerated or patch like lesions.Anterior nares:If pus is present is present, collect iton the swabs.If no pus is present, moisten theswabs and then swab the anteriornares.Troat: The mouth is held wide open andthe tongue is depressed. Swabs arefirmly rubbed over the tonsils andpharyngeal mucosa.
  11. 11. Nasopharynx :A pernasal swab is used. This is made from fairly flexible wirewhich is bent at one end and is covered with sterile cotton at thisend. The swab is carefully passed through the cavity till itimpinges on the nasopharynx and then firmly rubbed over thearea.Epiglottis :Swabs are firmly rubbed over the inflamed and ulcerated areas.Before collecting the swabs precautions should be taken tomaintain the airways in case a laryngeal spasm suddenlyoccurs. Ideally the swabs should be taken by an ENT surgeon.Paranasal sinuses:If pus is present in these sinuses , it is collected on swabs oraspirated with a syringe and needle.
  12. 12. FROM LOWER RESPIRATORY TRACTᵜCommonly only sputum is collected. This should becoughed up from far down the bronchial tree andexpectorated immediately. It should not be mixed withsaliva or other oropharyngeal secretions.ᵜAn even better specimens material that is aspirateddirectly from the bronchi or trachea. This is collected byusing a flexible fibreoptic bronchoscope.ᵜAn alternative is to collect bronchial washings.ᵜThese procedures should be conducted by anexperienced pulmonologist or cardio thoracic surgeon.
  13. 13. FROM THE GASTROINTESTINAL TRACT WINTER Feces is collected on a sterile wide mouthed , leak Templateproof container preferably provided with a small spoonto 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 shortcatheter into the rectum. A rectal swab can be collected as an alternative : thisis gently inserted into the rectum and turned clockwiseand anti clockwise ensuring the rectal mucosa is firmlyrubbed.
  14. 14. FROM URINARY TRACT Contamination of urine by bacteria colonizing thedistal parts of the urethra and the perenium isprevented by clean catch technique. Here the periurethral area is cleaned twice with soapand water. The urethra is flushed by voiding the first portion ofthe urine , which is discarded. The subsequent mid stream urine is collecteddirectly in a sterile container and is used for cultureand colony counting. It is essential for cultural purposes that urine beprocessed within one hour of collection or stored in arefrigerator at 40 C till it can be cultured.
  15. 15. FROM THE GENITAL TRACTIn women: The best specimen is a cervical swab. A sterile bivalvespeculum is moistened with warm water and inserted into thevagina. The cervical mucus plug is removed with a cotton balland forceps: the external surface of the cervix is then cleanedwith a large cotton swab.In men:If the patient has purulent urethral exudates, culture is notnecessary. A Gram stained direct smear is enough for clinicaldiagnosis of Gonorrhea if intracellular gram negative diplococcicare seen. In men, uncentifuged first voided urine may becultured for N. gonorrhea .
  16. 16. FROM CENTRAL NERVOUS SYSTEMᴪThe Cerebro Spinal Fluid is usually collected fromlumbar puncture.ᴪThe dural sheath is pierced by a needle and CSF isallowed to drip from it into a sterile container.ᴪIt is essential to avoid introducing contaminatingorganisms into the subdural space or the specimen.ᴪTherefore the procedure should be viewed as a minorsurgical operation.ᴪThe technique should be vigourously aseptic.
  17. 17. WINTER FROM THE BLOODSTREAMBlood is collected by strict aseptic technique and care Templateshould be taken to avoid introducing organisms into theblood stream as well as prevent contamination of thespecimen.The vein from which the blood is to be taken should beclearly seen and the skin overlying the vein is vigorouslywiped with 70% alcohol.Once the area is dry, the specimen is collected using aperfectly dry, sterile syringe and needle.After this, the area is cleaned with 70% alcohol andfinally wiped with povidine-iodine in alcohol.
  18. 18. FROM PLEURAL AND PERITONEAL CAVITIES۞. A sample of pleural fluid is collected by a doctor with asyringe and needle using a procedure called thoracentesis.۞The health care provider will clean the skin around theinsertion site and drape the area.۞A local anesthetic is injected into the skin.۞The thoracentesis needle is inserted above the rib into thepocket of fluid. As fluid drains into a collection bottle, manypeople cough a bit as the lung reexpands to fill the spacewhere fluid had been.۞This sensation normally lasts for a few hours after the testis completed.
  19. 19. 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.
  20. 20. CRITERIA FOR REJECTION OF SPECIMEN WINTERCriteria should be developed by a laboratory on the Templatebasis of which the processing of a specimen may notbe done by the laboratory. The following are someexamples:§ Missing or inadequate identification.§ Insufficient quantity.§ Specimen collected in an inappropriatecontainer.§ Contamination suspected.§ Inappropriate transport or storage.§ Unknown time delay.§ Haemolysed blood sample.
  21. 21. 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.
  22. 22. CONCLUSIONSpecimen collection is an essential prerequisite thatthe laboratory must be given sufficient clinicalinformation to guide the microbiologist in selection ofthe suitable media and appropriate techniques.Also, it is important for the clinician to appreciate thelimitations and potentials of the microbiologicallaboratory and to realize that a negative report doesnot necessarily invalidate the diagnosis. It is essential that a close cooperation and frequentconsultation among the clinician, nurse andmicrobiologist are the rule rather than exception.