Fluids from Normally Sterile Sites
The detection of organisms in fluids that are normally sterile
indicates significant infection, which can be life-threatening.
Specimens may be taken primarily for culture or this may be
incidental to the prime reason for obtaining the specimen.
Blood cultures may be positive with the same infecting organism,
and occasionally may be positive when culture of the fluid fails to
reveal the organism.
Fluids will be sterile in the absence of infection, as will
"sympathetic effusions", and those of immunological or traumatic
origin and those due to metabolic disease or heart failure.
Signs of infection may be difficult to detect clinically in
patients whose joints are already inflamed due to rheumatological
conditions. This is important because these patients are at
increased risk of joint sepsis.
Collection container (including preservatives):
Use aseptic technique.
Collect specimens in appropriate CE marked leak proof containers
and transport specimens in sealed plastic bags.
Specimen type: Universal
container: Amniotic fluid, bursa fluid, pericardial fluid,
synovial (joint) fluid, peritoneal fluid (ascites), pleural
Capped Syringes: Vitreous aspirates and other intra ocular
fluids should be injected into a Blood Culture bottle set with a
small syringe of fluid submitted for a Gram stain. The needle MUST
be removed before submission for the laboratory.
Collection: Collect specimens before
antimicrobial therapy where possible.
Specimen transport: Specimens should be
transported and processed as soon as possible
Minimum volume of sample: Ideally, a minimum
volume of 1 mL.
Large volume - specimens such as peritoneal fluid and ascitic
fluid may contain very low numbers of organisms which are usually
received in adequate quantities and require concentration to
increase the likelihood of successful culture.
Small volume - fluids such as synovial fluids may be received in
inadequate volumes, which may impede the recovery of organisms.
Enrichment culture is performed on all fluids from normally
sterile sites to enhance the recovery of bacterial pathogens.
Special precautions: If processing is delayed,
refrigeration is preferable to storage at ambient temperature.
Delays of over 48hr are undesirable.
Measurement units: X10 6/L for cell count
Biological reference units: Not applicable
Turn round time for provisional result (working
days): 30-60 mins for microscopy and Gram Stain, when
telephoned as Urgent.
Turn round time to final result (working days):
2- 3 days for direct culture result. 5 days for enriched culture
Clinical decision points: Positive microscopy
and/or Positive Culture results are telephoned to the requesting