The susceptibility methodology is dependent on the site of infection and/or the organism. In most cases, an MIC will be performed. Disk diffusion (Kirby-Bauer) will be performed on organisms such as mucoid pseudomonas, stenotrophomonas, Pseudomonas aeruginosa from CF patients, and if susceptibility is requested for additional drugs not available using the MIC methodology. Extended spectrum beta-Lactamase testing will be performed on Gram negative bacteria when indicated by susceptibility pattern. Beta-Lactamase testing (enzyme detection) will be performed on Gram positive bacteria when indicated by susceptibility pattern.
To determine susceptibility of a given organism to a panel of antimicrobic agents.
If a specific organism is isolated from the same specimen-related site of the same patient, susceptibilities will be performed upon initial isolation and at 7 day intervals thereafter. Contact the MLabs Client Services Center if testing is needed more frequently for a specific patient. Organisms which fail to grow will be reported as 'unable to perform susceptibility testing'. Susceptibility testing will not be performed on all bacterial isolates from a specimen; organisms tested depend on specimen source, quantity and presence of other bacteria in the culture.
24 - 48 hours after isolation of specific organism to be tested or isolate received
For all cultures, susceptibility testing is performed automatically on potentially pathogenic organism(s) at an additional charge unless specifically declined. To request susceptibility testing using antibiotics not normally tested, call the MLabs Client Services Center. Organisms will be held up to 7 days from the date specimen was received. For testing on actively growing organisms: 1) Aerobic Bacteria: Swab organism from pure culture and send swab in aerobic transport tube. Do not send plate. Transport at room temperature. (Swabs sent in aerobic transport do not require two-pouch SAF-T-PAK system.) 2) Anaerobic Bacteria: Place actively growing organism on anaerobic plate in an anaerobic transport bag. Place inside clear, liquid tight SAF-T-PAK bag and seal tape liner. Place sealed bag and requisition inside white biohazard SAF-T-PAK envelope and seal. Transport at room temperature.
Test includes a routine antimicrobial panel. Please contact the MLabs Client Services Center for additional antimicrobial agents. Minimum Bactericidal Concentration (MBC) testing is also available; contact the MLabs Client Services Center for further information. Beta-Lactamase testing will be performed at an additional charge when indicated by susceptibility pattern (ESBL or BLFEE). By ordering this test the clinician acknowledges that additional reflex testing will be performed and billed at a separate additional charge if indicated.