Antibiotic and Antifungal assays (amikacin teicoplanin gentamicin tobramycin vancomycin, flucytosine itraconazole posaconazole voriconazole )

Microbiology

Therapeutic drug monitoring is required for certain anti-infective agents in order to ensure appropriate serum levels have been achieved. The purpose is to ensure therapeutic levels have been attained and to minimise toxicity.
Routinely available assays include:
- Amikacin
- Flucytosine
- Itraconazole
- Posaconazole
- Voroconazole
- Teicoplanin
- Gentamicin
- Tobramycin
- Vancomycin
Therapeutic levels for the first five agents are shown in the table later on this page. See links for further information on the last four antibiotics on this list.
Other anti-infective agents may be assayed on request. Please discuss with the Consultant Microbiologist prior to obtaining any samples. Comments on the interpretation of assay values will included in the report.
Blood samples from HIV positive patients must be heat treated before they are sent to the reference laboratory. Please ensure that the laboratory is informed if samples are from an HIV positive patient.

Results are reported with a standard interpretative comment that gives the recommended target (normal) levels
If there is any doubt regarding interpretation, contact the Consultant Microbiologist

Serum - refer to the table below for collection requirements

Amikacin, flucytosine

8.5ml of blood taken into a plain gel tube

Itraconazole, posconazole, voroconazole

6ml of blood taken into a plain serum tube with no additives

Agent	When to collect
IV amikacin once daily	See antibiotic guidelines
IV amikacin BD/TDS	See antibiotic guidelines
Oral flucytosine	pre-dose and 2 hours post-dose
IV flucytosine	pre-dose and 30 minutes post-dose
Oral or IV itraconazole	pre-dose after 7 days
Oral posaconazole	pre-dose after 5 days
Oral voriconazole	pre-dose after 3-5 days

Store at fridge temperature

Transport as soon as possible at ambient temperature

Sent to a to a Regional Reference Centre.

Up to 5 days