NTU Undergraduates' research April 2014 - Biosciences | Page 32

Comparison of a Non-Chromogenic Agar Method and a Chromogenic
Agar Method for the Identification of Target Organisms Present on
Routine Wound and Nose Swabs in a Clinical Microbiology Laboratory
Setting
King, Sylvia
Nottingham University Hospital Queens Medical Centre Department of Clinical
Microbiology, Nottingham Trent University
Abstract
Finding alternative methods for processing samples that reduce costs and require less skill to interpret
could help to reduce the financial burden on clinical microbiology departments. Wound swabs are a
substantial component of a microbiology laboratory’s workload; a non-chromogenic method was
compared to a chromogenic method for processing 200 wound samples. Sensitivity of results, cost
and time required to interpret results was compared for both methods. The Chromogenic method was
marginally more sensitive than the current method used; however, the chromogenic method would
lead to a large increase in costs if implemented and took longer to interpret and therefore, it was
concluded that the current method should remain. In cases where the clinical details indicate that a
patient may be at an increased risk of developing an infection with a specific target organism the
addition of a chromogenic plate may be beneficial. Screening pre-operative patients for the nasal
carriage of Staphylocococus aureus allows for decolonization treatment to be implemented, when
required, prior to surgery reducing the number of post-operative Staphylocococus aureus infections.
The current, non-chromogenic, method for the identification of Staphylocococus aureus carriage was
compared to a chromogenic method on 50 nose swabs. The chromogenic method was marginally less
sensitive than the current method used and the chromogenic plates were more expensive; however, the
chromogenic method reduced time and costs as there was no further work required and was quicker to
read than the current method used. Therefore, the chromogenic method may be a via &