The special affinity of particular types of Proteus mirabilis for the urinary tract.

The strains of Proteus species found in significant numbers and as pure cultures in urine from 217 individuals were isolated, identified to species level and typed for proticine production (P type) and proticine sensitivity (S type) to give their P/S type. Urinary-tract infections with Proteus, principally P. mirabilis, were associated with the elderly. Ninety seven distinct P/S types were found but three P/S types P3/S1,8, P3/S1,8,13 and P3/S1,13 were isolated at a much higher frequency (14%) then could be explained from their faecal carriage rate. These types were almost without exception restricted to patients with clinical symptoms of urinary-tract infection and it is suggested therefore that they have some special affinity for the urinary tract.