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Lab Manual for UCSF Clinical Laboratories

Lab Manual for SFGH

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ANTIMICROBIAL SERUM KILLING LEVEL (SKL)

Item Value
Available Stat? No
Test code MC
Performed by? Microbiology
Sendout? no
Price range $$
In House Availability Request and schedule through Microbiology Resident, 206-5699 or pager (415) 443-1438.
Principle Serial two-fold dilutions of the patient's serum are inoculated with a standardized suspension of the patient's bacterial isolate. The result for the inhibitory titer, the highest titer of serum showing no visible growth, is available after 24 hours. Subcultures of the dilutions are made so that the serum killing level, or SKL, can be determined. The serum killing level is that dilution of serum that demonstrates a three log (i.e., 99.9%) killing of the initial inoculum.
Interpretation Varying opinions exist about the usefulness of SKL's for monitoring the therapy of endocarditis and osteomyelitis. Its use in other infections is of no value. The SKL gives an approximation of whether adequate therapeutic levels have been achieved when changing from a parenteral to an oral antimicrobial.
Amount to Collect 10 mL
Collection Instructions Blood sample must be obtained using aseptic technique. We recommend that samples be drawn at the time of peak anti-microbial concentration in blood. Included in Table M II is the approximate time after dosing, when peak serum concentrations are reached for various antibiotics. Special Antimicrobials Forms are available in the lab (206-8576). Please state the time drawn relative to dosing and the antibiotics administered. Deliver to Microbiology (2M33) immediately.
Sample type Blood
Special instructions This test can be done only when the bacterium isolated from the patient is alive and available in the laboratory. Laboratory must be notified a day in advance of submitting a specimen so that the patient's bacteria can be grown.
Normal range Interpretation requires consultation with Infectious Diseases (Med: 443-2847, Peds: 443-9503).
Synonyms Serum Killing Level (SKL, Serum Cidal Test, Serum Antimicrobial Titer);SKL (Serum Killing Level);
References National Committee for Clinical Laboratory Standards (NCCLS), Methodology for the Serum Bactericidal Test; Approved Guideline, Document M21A vol.19 No.17, September 1999.
Last Updated 4/30/2011 10:21:20 AM
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