Download specimen collection - University of Glasgow

University of Glasgow Sepsis Acute Care Day
SPECIMEN COLLECTION
The first and most important step in microbial identification.
Microbial identification / isolation in infectious disease
Identifying the organism can predict disease severity, likely course and possible antibiotic
sensitivity.
Isolating the organism determines the actual antibiotic sensitivity. This is only useful if
the organism is the infecting pathogen causing the disease process. Therefore, collecting
the sample accurately and without contaminants is important.
Specific Points
Protect yourself, the patient and sample validity; ALWAYS wear gloves and aprons
when dealing with infected materials.
Take extra care with infected fluids and ensure containers tightly sealed.
General Rules
Quantity: (send enough e.g. 20ml blood for blood cultures)
Representative sample: Take form the actual infectious site.
Avoid contaminants:
Wound swab: avoid surrounding skin, gently clean, swab and store at room temperature.
Sputum: rinse mouth with saline or water (not mouthwash). This reduces contamination
with normal oropharyngeal flora.
MSSU: ensure adequate cleansing of peri-urethral area for "clean catch"/Mid Stream
Specimen of Urine.
Catheter Sample of Urine (CSU): direct from catheter, not catheter bag.
Drain Fluid: direct from the drain, again not from the drain bag.
Use aseptic techniques, sterile equipment and containers.
Transporting and timing
Deliver all specimens to the lab as soon as possible, over time pathogens die and
commensals overgrow therefore the sample becomes unrepresentative.
Specimens for bacterial culture should be kept at room temperature.
If delay in delivery, store in a fridge (urine, sputum), except blood cultures and CSF, they
should be stored at 37°C, therefore place in an incubator.
Specimens should be tightly sealed in leak-proof plastic bags.
Specimens for TB investigation should be “double-bagged”
Externally contaminated specimen containers may be rejected by the lab.
Whenever possible obtain samples before antibiotics started.
Sensitive organisms won't grow.
Organisms appear different post-antibiotics therefore specimens hard to interpret.
University of Glasgow Sepsis Acute Care Day
For antibiotic assays e.g. vancomycin, gentamicin, vital to consider when levels need to
be sampled (pre/post dose levels), coordinate drug administration with person taking
blood.
Labelling specimen & request form:
Give as much information as possible.
Name
DOB
Hospital number/CHI Number
Collection Date and Time
Specimen type/Site of Sample (e.g. Blood/Right Subclavian CVC)
Ward
Consultant
Clinical Information, history, examination, differential diagnosis, patient
condition, improves interpretation of the result.
INCORRECTLY LABELLED SAMPLES CANNOT BE PROCESSED
Specific Samples
Blood cultures
Skin decontamination with 2% Chlorhexidine.
Allow each one minute to act.
Sterile venepuncture from peripheral sites “No touch technique”
Decontaminate the bottle tops with 70% alcohol only.
Draw 20ml of blood (for adults and older children), inoculate aerobic and anaerobic
bottle with 10ml each. Change needles after venepuncture and between bottles.
For infants draw 0.5-3ml of blood, inoculate paediatric blood culture bottle as above.
Draw blood from intravenous catheters if suspect line infection, therefore a patient with a
suspected line infection should have sets of blood cultures taken from all lines as well as
peripherally.
In suspected endocarditis, three sets of blood culture over two hours from different sites
required.
In laboratory, bottles loaded up in an automated system (Bact Alert)
DO NOT CALL DAILY TO ENQUIRE ABOUT BLOOD CULTURES.WE WILL
CALL YOU WITH POSITIVE RESULTS.
Positive blood cultures processed for Gram stain, microscopy and subculture on media.
(No Gram stain of freshly taken blood.)
Intravenous catheters
If suspect infection, remove.
Send 5cm of distal tip in a universal container.
Sputum
If expectorated, rinse mouth and gargle with water beforehand if possible.
If induced, brush gums and teeth, rinse with water, and use nebuliser to induce sputum.
All sputum samples to be sent in a sterile container.
No microscopy on sputum, only culture
Bronchoalveolar lavage (BAL) / Bronchial brushing / Endotracheal aspirates to be sent in
a sputum trap container.
University of Glasgow Sepsis Acute Care Day
BAL / Pleural effusion / Empyema get microscopy and culture.
Investigation of Atypical Pneumonia
Viral throat swab in viral transport medium.
Pneumococcal antigen
Urine for Legionella urinary antigen.
In view of recent H1N1 cases, it is best to call the lab prior to taking these samples to
clarify what exactly is required.
Investigation for TB
Sputum: 3 early morning sputum samples on 3 consecutive days, with 5-10ml in sterile
containers.
Urine: 3 Early Morning Urine (EMU) specimens, in a sterile container (150ml), one per
day.
Stool: 5-10 g x 3
Specimens processed for acid alcohol fast bacilli by Auramine or Ziehl-Neelsen staining
and TB cultures.
Sterile Body Fluids
Ascitic fluid, joint aspirates
Disinfect overlying skin with 2% chlorhexidine
Obtain sample with needle and syringe, transfer fluid to sterile container.
Never submit a swab dipped in fluid.
Never send the needle to the lab unless already discussed with Microbiologist.
Ulcer and Wound Swabs
Surface decontamination
Coat the sterile swab in the material from the base.
Abscesses
Use needle and syringe to aspirate.
Pus more useful than a swab dipped in pus.
Gram stain and microscopy on aspirates.
Cerebro-Spinal Fluid (CSF)
Skin decontamination, sterile lumbar puncture
Send 1-5ml of fluid in sterile container immediately
For out of hour specimens liaise with microbiologist.
For cell count, Gram stain, microscopy and culture.
Depending on clinical history also for virology, Tuberculosis, etc.
Urine
1-10ml of urine (MSSU, CSU, Suprapubic aspirate) in a sterile container with Boric
Acid.
Enteric
10-20g of stool in sterile containers
Clinical and travel history will determine the extent of investigation.