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Collection and transport of biological specimens
Biological specimens
Depending on source:• sterile collection sites:
– Blood, CSF, urine
• contaminated collection sites:– Faeces, naso-pharyngeal secretion, pus, vaginal
secretion
+ specimens from sterile collection sites which may be contaminated during elimination e.g. sputum, urine
Parameters to be considered when collecting biological specimens
• WHAT: choice of biological specimen depending on clinical stage
• WHEN: optimal moment of collection; maximum time to reach the laboratory
• HOW: collection procedure (avoid contamination of specimen); instruments (sterile !!); manipulation and packaging (no contamination of staff and environment)
• HOW MUCH: adequate quantity for required tests
Minimal Information in Request form
• About patient: ID, age, gender• About disease: date of onset, suspected
diagnosis/causative pathogen
• About specimen: type of specimen, collection site, time of collection, time of shipment, storage conditions (if applicable)
• About referring physician – contact data (name, phone no)
Microbiological tests: Most often referred specimens
• Biological samples: secretions, excretions, tissues, organ fragments
• Food samples
• Pharmaceutic products, cosmetics
• Environmental samples: water, air, soil
General requirements for collecting pharyngeal, naso-pharingeal exudate
• For the patient: – in the morning, before feeding, before brushing teeth;
alternatively: at least 4 hours since last meal & teeth brushing
– No mouth rinse, no chewing gum!
– No antibiotics during the last 7-10 days
• For medical staff:– Wear gloves, face protection (mask, eye
protection/face shield), protective lab coat
Collection of pharyngeal exudate
• Dacron or Rayon swab• Tongue blade & good light• Insert swab behind uvula
without touching it
• Swab tonsils, posterior
pharynx + lesions (if any)• Avoid touching tongue,
cheeks, teeth• Place swab in sterile tube
• Transport to lab (RT/2-8°C)
Collection of pharyngeal exudate
Collection of nasal/nasopharyngeal exudate
• Head of patient imobilised in neck extension• Sterile swab gently inserted through nostril along nasal
floor until reaching posterior pharingeal wall• Rotate swab, withdraw slowly + reinsert and repeat steps
• Take out and insert into sterile tube
• Send to lab
Collection of sputum
• Challenging! – must avoid contamination of sputum with saliva and secretions from upper air ways
Optimal moment: in the morning (higher amount of sputum secreted during the night and stagnant in lower respiratory ways)
Indirect method:• Patient energically rinses mouth with saline solution
• Coughs and expectorates in sterile container (Petri dish)
Direct method:• Bronchoscopy / tracheal punctioning
Collection of Blood
• Normally sterile biological product
• Collection technique depends on the required tests:– A. bacteriology = hemoculture– B. Serology
A. Blood collection for hemoculture
Blood injected in 2
sets of sealed bottles
containing liquid culture
medium for aerobic and
anaerobic bacterial
growth
Collection of blood for hemoculture
• Wear gloves + PPE• Thoroughly wipe skin with antiseptic (chlorhexidine,
iodine, alcohol)• During 3 hours, draw blood by venipuncture from up to 3
different sites at 1 hour interval (3 sets of 2 bottles each) – around 5 ml blood per bottle
• After drawing the blood, dispose of the syring needle and attach new, sterile needle
• Disinfect cap of each culture medium bottle and inject 5 ml blood/bottle
Collection of blood for hemoculture
Automated systems for detection of bacteria in blood and other normally sterile body fluids
B. Blood collection for serology
• similar PPE used by person collecting sample (gloves, lab coat, eye protection, etc)
• Thorough skin decontamination with antiseptic • Blood drawn by venipuncture with:• sterile syringe and needle and injected/inserted in sterile
container
• Vacuum collecting system (tube + needle): blood drawn by vacuum into tube containing clot activating substance (facilitates clot formation & separation of serum)
B. Blood collection for serology
Collection of Pus
• Composition: white blood cells, microbes, cell debris, fibrin
Closed purulent lesions (abscesses): • surgical collection:
– rigurous cleaning and disinfection of skin (iodine)
– Incision and aspiration of pus
Open lesions:
• Cleaning and disinfection of skin around lesion (iodine)
• Collection of pus with sterile swab / loop
Collection of stool (faeces)
• Disposable stool collection containers (simple / with transportation medium Carry Blair: non-nutritive medium which prevents overgrowth of Enterobacteriaceae but preserves viable enteric pathogens (Salmonella, Shigella, Vibrio, etc)
Collection of urine
When?:
- in the morning (first miction)
How?: - clean uro-genital area
- eliminate first flow
- collect middle flow in
sterile container
Send to lab immediately or store
at 2-8°C
Collection of cerebrospinal fluid (CSF)
Lumbar punction (spinal tap) • patient lies on the side, knees pulled up toward
chest, chin tucked downward • back cleaned and disinfected (iodine) + health
care provider injects local anesthetic into lower spine
• spinal needle inserted into lower back area• needle properly positioned, CSF pressure
measured and sample collected in sterile tube• needle removed, area cleaned, bandage placed
over puncture site