Feasibility of using microbiology diagnostic tests of moderate or high complexity at the point - of - care in a delivery suite.

Point-of-care testing (POCT) is one of the fastest growing sectors of laboratory diagnostics. Most tests in routine use are haematology or biochemistry tests that are of low complexity. Microbiology POCT has been constrained by a lack of tests that are both accurate and of low complexity. We describe our experience of the practical issues around using more complex POCT for detection of Group B streptococci (GBS) in swabs from labouring women. We evaluated two tests for their feasibility in POCT: an optical immune assay (Biostar OIA Strep B, Inverness Medical, Princetown, NJ) and a PCR (IDI-Strep B, Cepheid, Sunnyvale, CA), which have been categorised as being of moderate and high complexity, respectively. A total of 12 unqualified midwifery assistants (MA) were trained to undertake testing on the delivery suite. A systematic approach to the introduction and management of POC testing was used. Modelling showed that the probability of test results being available within a clinically useful timescale was high. However, in the clinical setting, we found it impossible to maintain reliable availability of trained testers. Implementation of more complex POC testing is technically feasible, but it is expensive, and may be difficult to achieve in a busy delivery suite.

Use of cultured cells to study the relationship between arachidonic acid and endothelium-derived relaxing factor.

We have used mixed- and co-cultures of endothelial and vascular smooth muscle cells to investigate the role of phospholipase activation and arachidonic acid metabolites in the production of endothelium-derived relaxing factor (EDRF). Inhibition of phospholipase A2 with para-bromophenacyl bromide, dexamethasone or quinacrine, alone or in combination, blocked arachidonate release by 50%-60% but had no effect on EDRF production as assessed by cyclic GMP accumulation in mixed- or co-cultures of endothelial and vascular smooth muscle cells. Inhibition of the phospholipase C-diacylglycerol (DAG) lipase pathway of arachidonate release by the DAG lipase inhibitor RHC-80267 also caused partial inhibition of arachidonate release and had no effect on EDRF. When both phospholipase A2 and phospholipase C pathways for arachidonate mobilization were inhibited (dexamethasone + RHC 80267), arachidonate release was totally inhibited while EDRF release remained intact. We conclude that neither phospholipase activation nor arachidonate mobilization is required for EDRF release from cultured bovine endothelial cells.