Controversies in the laboratory diagnosis of community-acquired urinary tract infection

Urine samples constitute the largest single category of specimens examined in most medical microbiology laboratories. The everyday nature and apparent simplicity of urinary tract infection belies the intense debate and controversy regarding the optimal methods of collection, transport and processing of urine specimens and reporting of results. There is considerable variation in the interpretation of quantitative culture results between laboratories and the etiology of abacterial cystitis remains unclear. Microscopy to detect pyuria provides information on an important indicator of inflammation and it has been proposed that detection of urinary antibody may provide similar information. Neither of these indices of host response is suitable for use in a screening test for urinary infection however, although they may usefully contribute to the interpretation of significance of culture results. The development of screening tests and automated systems continues, but at present microscopy and culture remain the most important techniques for laboratory diagnosis. However, these techniques have so far failed to provide an etiological diagnosis for abacterial cystitis and this remains a major area for research.