ANTIBIOTIC ASSAYS
Gentamicin 
There are two dosing regimens for Gentamicin in adults; once daily and three times daily. Monitoring for each regimen is different.
 
Once daily regimen
Mid dose levels are needed 6-14 hours post dose. The nomogram used to interpret levels and adjust doses which are given every 24 hours is available on the intranet and at all ward areas. The exact time of each dose administered and blood sample taken, must be recorded on the drug chart.
 
Three times daily (TDS) regimen
Pre-dose (trough) and post-dose (peak) levels should be sent.  These should  be taken immediately before, and 1 hour after the i.v. or  i.m. dose respectively.  Assays should initially be sent around the third or fourth dose (earlier in patients with impaired renal function).  Once stable levels have been achieved, assays should be sent 2-3 times per week.  Random samples should not be sent; please state the time interval since the last dose was given.
For interpretation of results (including reference ranges) please refer to guidelines on the Intranet/ward areas.
 
Vancomycin
Monitoring is done by taking a pre dose level (trough) immediately prior to administration of next dose. If a twice a day regimen is being used the first pre-dose level is taken immediately before the third dose.  If a once a day regimen is being used, take level immediately before second dose.  For both regimens there is no need to take post dose levels.
For interpretation of results (including reference ranges) please refer to guidelines on the Intranet/ward areas.
 
For other antibiotic assays, please discuss with the Clinical Microbiologist before sending samples.
Note:  Assays for Tobramycin,  Gentamicin and Vancomycin levels are currently  performed in the Biochemistry Department.

 
SEROLOGICAL INVESTIGATIONS for PUO and viral infections
For the detection of antibody, please send paired serum samples (10-14 days apart) whenever possible.  The first sample should be sent at presentation.  Occasionally a single high titre may be diagnostic.  Detection of antigen requires a single blood sample in a Serum Gel Monovette (brown top).  Relevant clinical details and an indication of the date of onset of symptoms are required to enable appropriate selection of investigations.
 
BLOOD SAMPLE VOLUMES
Where possible a minimum of 5ml (1 Monovette) up to 10mls (2 Monovettes) of clotted blood should be sent. The more tests requested the more blood should be sent. In the case of babies and small children 1 to 3 500ul paediatric tubes should suffice.
Please Note:     We will always try to test low volume samples wherever possible to prevent the re-bleeding of patients but we cannot guarantee success.