MLAB 2434 – CLINICAL MICROBIOLOGY SUMMER, 2005 CECILE SANDERS & KERI BROPHY Chapter 7 – General Concepts in Specimen Collection and Handling

Chapter 7- General Concepts in Specimen Collection and Handling (cont’d) Basic Principles of Specimen Collection Specimen should be taken in acute phase of infection AND before antibiotics are administered Written order must specify site of culture (example: wound on left arm)

Chapter 7- General Concepts in Specimen Collection and Handling (cont’d) Avoid normal flora and colonizing organisms Compare test results with suspected diagnosis

Chapter 7- General Concepts in Specimen Collection and Handling (cont’d) Appropriate Collection Techniques Aspirates and tissues Aspirates and tissues present few problems, if collected using sterile technique Lesions, wounds and abscesses; cultures should be from as deep in the wound as possible

Chapter 7- General Concepts in Specimen Collection and Handling (cont’d) Swabs Used only as a last resort Steps Clean wound Explore wound Obtain fresh and quality culture material Should be placed in a holding medium to protect pathogens without permitting multiplication during transport

Chapter 7- General Concepts in Specimen Collection and Handling (cont’d) Patient Education and Preparation If patient is responsible for collecting specimen, good instructions are critical Urine – midstream clean catch first morning specimen Sputum – collect sputum NOT spit Stools – usually 3 vials and at least 4 days after barium Xrays

Chapter 7- General Concepts in Specimen Collection and Handling (cont’d) Preservation, Storage, and Transport of Specimens Concerns Overgrowth Death of microorganisms Inaccurate quantitation Loss of organisms from drying Protection from oxygen Protection from clotting Safety of transporter

Chapter 7- General Concepts in Specimen Collection and Handling (cont’d) Preservatives Urine – boric acid Stool – phosphate-buffered saline (PBS) Anticoagulants Needed in any specimen that might clot (blood, serum, joint fluids) Sodium polyanethol sulfonate (SPS)

Chapter 7- General Concepts in Specimen Collection and Handling (cont’d) Use of Holding and Transport Media Swabs placed in Modified Stuart transport medium or Cary-Blair transport medium Blood placed in broth culture medium Unprotected specimens Sputums, body fluids, tissues, catheters, medical devices, and specimens for sterility culture Should be processed ASAP

Chapter 7- General Concepts in Specimen Collection and Handling (cont’d) Storage of Specimens Urine, viral blood specimens, catheters and swabs should be refrigerated Blood and CSF should be processed ASAP Specimens for fungus cultures can be kept at room temperature Respiratory and stool cultures should be processed ASAP if at all possible, but refrigerated if immediate processing is not possible

Chapter 7- General Concepts in Specimen Collection and Handling (cont’d) Mailing Specimens Regulated by U.S. Dept. of Health and Human Services Primary container must be securely closed, watertight Secondary container has sufficient absorbent material to absorb contents in case of breakage Final container is an approved mailing container with biohazard symbol and contact phone number for CDC Page 244 in textbook

Chapter 7- General Concepts in Specimen Collection and Handling (cont’d) Safety Universal Precautions Specimen processing should be conducted in a Class II safety cabinet (hood) Labeling and Rejection of Specimens Requisitions must include source, diagnosis or history, and test(s) requested

Chapter 7- General Concepts in Specimen Collection and Handling (cont’d) Unacceptable Specimens Labels on requisition and on specimen must match Noninvasive vs. invasive specimens Rejected specimens Leaking Syringes with needles attached Stools contaminated with urine or barium Anaerobic cultures on inappropriate sources Unpreserved specimens over 2 hours old

Chapter 7- General Concepts in Specimen Collection and Handling (cont’d) Refrigerated blood cultures Dried-up specimens Specimens in formalin Processing of Clinical Samples for Optimal Organism Recovery Prioritization (Table 7-2, p. 247) Level 1- Critical/invasive Level 2 – Unpreserved Level 3 – Accuracy of quantitation affected Level 4 – Protected/Preserved

Chapter 7- General Concepts in Specimen Collection and Handling (cont’d) Gross Examination of Specimens – check specimen and requisition Direct Examination Techniques Direct Microscopic Examination (Table 7-3, p. 250, text) Determine quality of specimen Diagnose infectious disease Guide routine culture interpretation Dictate the need for nonroutine processing

Chapter 7- General Concepts in Specimen Collection and Handling (cont’d) Smear Preparation Tissues Swabs Aspirates and body fluids Single drop smear Centrifuged sediment smear Layered smear Cytocentrifuged smear Additives

Chapter 7- General Concepts in Specimen Collection and Handling (cont’d) Direct Smears NOT useful Throats, nasopharyngeal swabs Urine Female genital tract Primary Inoculation of Routine Specimens Types of Culture Media Nonselective vs. Selective Differential Enriched Broths