Susceptibility testing performed in general practice by urinary tract infections.

Demonstration of significant bacteriuria by quantitative culture of a urine specimen by use of dip-slides is a well proved diagnostic procedure in general practice. Susceptibility testing from urine specimens by use of dip-slides or agar-plates seems likewise easy to perform in general practice, but commercial methods, modified for use in general practice by simplification of the standard disc diffusion method involve possible sources of errors. In a multipractice study, the predictive values of results from susceptibility testing in general practice from urine specimens, by use of two commercial methods are calculated. A considerable number of errors were found, mainly because susceptible bacteria were classified as resistant. The consequence of this is certainly that patients are treated with a drug, which is effective against the infecting organism, but the clinician possibilities for choice of drugs will be limited more than necessary.