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HelpTest Code CXCSF Culture, CSF
Performing Laboratory
North Ottawa Community Hospital
Specimen Requirements
Specimen Type: Spinal fluid
Container/Tube: Screw-capped, sterile vial
Specimen Volume: 3 mL
Collection Instructions:
1. At the time of a lumbar puncture, cerebrospinal fluid is obtained by the physician and divided into the 4 sterile collection tubes supplied in the lumbar puncture kit.
2. Label vials with patient’s name, date of birth, and date and time of collection.
3. Specimen should not be left in the laboratory, but given to a laboratory technician for immediate processing.
Additional Information: A Gram stain is included on all cerebrospinal fluid cultures and is performed STAT.
Forms: A request slip for cerebrospinal fluid should be completed.
Specimen Transport Temperature
Ambient
Day(s) Test Set Up
Monday through Sunday
Reference Values
No growth in 72 hours
Methodology
Conventional Culture Technique
Includes a Gram stain.
Method Description
Specimens are cultured to enriched and/or selective media appropriate to the anatomic location and the scope of microorganisms expected. Cultures are incubated for 3 to 7 days depending on the specimen source. Pathogens or possible pathogens are identified using conventional biochemical tests in combination with BioMerieux Vitek® 2 automated identification system. Susceptibility testing is performed using either the Vitek® 2 automated antimicrobial susceptibility testing system or manual disk diffusion susceptibility testing.
When antimicrobial susceptibility testing is performed, testing is performed on pure culture isolates of pathogenic (or potentially pathogenic) bacteria grown from specimens that have been appropriately collected, so as not to confuse clinically significant isolates with normal flora.
Antimicrobial susceptibility testing determines the minimal inhibitory concentration (MIC) value of selected antimicrobial agents against isolated potentially pathogenic bacteria. The MIC is the lowest antimicrobial concentration that inhibits growth of the bacterium. Clinical breakpoints (interpretive criteria) applied are published by Clinical and Laboratory Standards Institute (CLSI) M100-S30, 2020.
MIC Reference Values
NI (no interpretation)
In some instances, an interpretive category cannot be provided based on available data.
S (susceptible)
A category defined by a breakpoint that implies that isolates with an MIC at or below or a zone diameter at or above the susceptible breakpoint are inhibited by the usually achievable concentrations of antimicrobial agent when the dosage recommended to treat the site of infection is used, resulting in likely clinical efficacy.
SDD (susceptible-dose dependent)
A category defined by a breakpoint that implies that susceptibility of an isolate depends on the dosing regimen that is used in the patient. To achieve levels that are likely to be clinically effective against isolates for which the susceptibility testing results are in the susceptible-dose dependent (SDD) category, it is necessary to use a dosing regimen (ie, higher doses, more frequent doses, or both) that results in higher drug exposure than that achieved with the dose that was used to establish the susceptible breakpoint. Consideration should be given to the maximum literature-supported dosage regimens, because higher-exposure gives the highest probability of adequate coverage of a SDD isolate. The drug label should be consulted for recommended doses and adjustment for organ function.
I (intermediate)
A category defined by a breakpoint that includes isolates with MICs or zone diameters within the intermediate range that approach usually attainable blood and tissue levels and/or for which response rates may be lower than for susceptible isolates.
Note: The intermediate category implies clinical efficacy in body sites where the drugs are physiologically concentrated or when a higher-than-normal dosage of a drug can be used. This category also includes a buffer zone, which should prevent small, uncontrolled, technical factors from causing major discrepancies in interpretations, especially for drugs with narrow pharmacotoxicity margins.
R (resistant)
A category defined by a breakpoint that implies that isolates with an MIC at or above or a zone diameter at or below the resistant breakpoint are not inhibited by the usually achievable concentrations of the agent with normal dosage schedules and/or that demonstrate MICs or zone diameters that fall in the range in which specific microbial resistance mechanisms are likely, and clinical efficacy of the agent against the isolate has not been reliably shown in treatment studies.
Test Classification and CPT Coding
87070-Culture
87205-Gram stain
If indicated, additional testing and charges may apply.