Impact of Xpert MRSA/SA blood culture PCR assay on management of positive blood cultures in obstetric patients: a retrospective audit.

BACKGROUND: The Xpert MRSA/SA blood culture assay (Cepheid, USA) is a rapid PCR test which can be used for positive blood cultures where Gram-positive cocci in clusters are seen. It can detect Staphylococcus aureus and also the mecA gene, which encodes for β-lactam resistance. The assay was introduced into the Rotunda Hospital for positive blood cultures to allow earlier detection of MRSA and methicillin susceptible S. aureus. AIM: To assess the impact of the Xpert MRSA/SA blood culture assay on the management of obstetric patients with a positive blood culture where Gram-positive cocci in clusters were seen. The main outcome measures were duration of intravenous antimicrobials and length of admission.
METHODS: Pre-intervention and post-intervention groups were identified relating to whether or not the test was in use at the time. A standardised form was used to retrospectively review the medical notes and laboratory results.
RESULTS: There were 35 obstetric patients with positive blood cultures with Gram-positive cocci in clusters in the pre-intervention group and 22 cases in the post-intervention group. All 22 positive blood cultures in the post-intervention period were correctly identified. The antimicrobial duration was reduced from a median of 55.5-43.5 h and length of admission reduced from a median of 66.5-56 h (Mann-Whitney U value = 161, p = 0.46 and U value = 256, p = 0.15, respectively).
CONCLUSION: This study has shown a reduction in the median duration of intravenous antimicrobials and admission; however, larger multi-centre studies are needed to evaluate this potential benefit further.