MLAB 2434 – CLINICAL MICROBIOLOGY SUMMER, 2005 CECILE SANDERS & KERI BROPHY

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

2. 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)

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

4. 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

5. 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

6. 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

7. 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

8. 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)

9. 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

10. 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

11. 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

12. 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

13. 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

14. 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

15. 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

16. 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

17. 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