Specimen Collection, Transport, and Processing

• Transport medium - allows organisms to survive
• Transport medium are non-nutritive, they do not allow organisms to proliferate
• Cary Blair - example of transport medium for bacteria
• Virus Transport Media - transport medium for viruses
• Pre-analytical phase - often overlooked; perhaps the most critical phase that labs have little experience with
• Rule of thumb: Garbage in = garbage out
• Optimal timing for respiratory swabs is within 3 days of onset
• Whole blood/plasma and CSF must be collected ASAP after onset
• For bacterial specimens, collection must be done prior to antimicrobial therapy
• For serology specimens, it must be refrigerated in 4-8 degrees C if for 24-48 hours and in -20 degrees C if for longer periods
• For serology specimens, make sure that acute and convalescent serums are labeled as such
• PCR tests generally require <1 mL of sample
• >3.0 mL of VTM is appropriate
• For decontaminating spills, 10% bleach should be used
• For disinfecting areas, 1% of household bleach should be used daily
• Contact precautions - for illnesses transmitted by direct patient contact or by contact with items in the patient's environment; uses gloves and gown
• Droplet precaution - for illnesses spread by large (>5 microns) droplets; utilizes contact precautions, well-fitting mask, and eye protection
• Airborne precaution - for illnesses transmitted by airborn droplet nuclei; uses contact and drop precautions, N95 mask, and isolation room
• Specimen collection kit - includes PPE, collection vials, items for sample collection, secondary container/cooler, ice packs, marker, labels
• Steps for collecting blood smears:

  1. Collect capillary blood from finger prick
  2. Make smear
  3. Fix with methanol or other fixative
  4. Transport slides within 24 hours; do not refrigerate
• Blood for culture utilizes venous blood, the amount is as follows:

  • Infants: 0.5-2 mL
  • Children: 2-5 mL
  • Adults: 5-10 mL
• Blood for culture should be collected within 10 minutes of fever; if bacterial endocarditis is suspected, collect 3 sets of blood culture
• Blood for cultures are collected in infusion broth, transported at ambient temperature, and stored at 4 C if it can't reach the laboratory within 24hrs
• Collection of serum utilizes venous blood which is then left to clot for 30 mins at ambient temparature
• For collecting serums, it is placed at 4-8 C for clot retraction at least 1-2 hours and is centrifuged at 1,500 RPM for 5-10 mins
• Serums should be transported at 4-8 C if less than 10 days or freezed at -20 C if for weeks and months
• To avoid hemolysis, do not freeze unseparated blood
• Cerebrospinal fluid - collected via lumbar puncture between L3, L4, and L5
• Clear - no visible particulates; transparent
• Hazy - few particulates, print easily seen
• Cloudy - many particulates, print blurred
• Turbid - print cannot be seen
• Milky - may precipitate or be clotted
• Faint aromatic odor - normal
• Ammonia-like - breakdown of urea
• foul, offensive odor - old specimen
• fruity/sweet - presence of ketones
• maple syrup - maple syrup urine syndrome
• rotting fish - trimethylaminuria
• mercaptan - after eating asparagus