Rare occurrence of Proteus vulgaris in faeces: a reason for its rare association with urinary tract infections

Abstract

Summary. The faecal carriage rates of different species of Proteeae were assessed in studies with 220 faecal isolates from 2 19 individuals of whom approximately one-third were well and the remainder had gastro-enteritis. As a result of the development of new media that allowed replacement of the phenylalanine deaminase test with the tryptophan deaminase test and made it possible to combine tests for indole and urease production and for hydrogen sulphide and ornithine decarboxylase formation in two single-tube tests, all strains were speciated with speed, economy and accuracy. Most (96%) isolates were either Proteus mirabilis (62%) or Morganella morgani (34%). The significance of these findings in relation to urinary tract infection is discussed. P. vulgaris was found in only one (0.45%) faecal specimen and this rarity of carriage in faeces is believed to be the main reason for its rare association with urinary tract infections. The frequent association of M . morgani, in the absence of other enteropathogenic bacteria, with severe gastroenteritis was noted with interest.

A survey of IgA protease production among clinical isolates of Proteeae

“…After overnight incubation at 37"C, strains which formed tryptophan deaminase (Senior and Leslie, 1986) and urease but failed to form acid from mannose were identified as Proteus spp. Those which formed tryptophan deaminase and acid from mannose were identified as species of either Morganella or Prouidencia.…”

“…Modified New York City medium (MNYC) was prepared according to the method of Young (1978) but with horse blood (Oxoid SR 50). Tryptophan deaminase agar (TDA), urea-indole medium, ornithine decarboxylase-H2S medium and peptone-water sugar media were prepared and sterilised as previously described (Senior and Leslie, 1986).…”

“…On the other hand, Morganella morgani and Providencia spp. are uncommonly associated with urinary-tract infections (Senior, 1979) but are more frequently associated with diarrhoea (Senior and Leslie, 1986). These differences arise through the operation of different pathogenic mechanisms in the different genera.…”

Production and properties of haemolysins from clinical isolates of the Proteeae

“…After sterilisation as above, horse red-blood cells (Oxoid SR50) were added to give a final concentration of 5% v/v. Tryptophan deaminase agar medium, urealindole medium, ornithine decarboxylase/H,S medium and peptone-water sugar media were prepared and sterilised as previously described (Senior and Leslie, 1986). Saline was 0.85% NaCl in water.…”

“…However, other members of the tribe Proteeae are rarely associated with urinary-tract infections and some are more often associated with diarrhoea (Senior, 1979(Senior, , 1983Senior and Leslie, 1986). Since Peerbooms et al (1983) have shown that the haemolysins produced by P. mirabilis influence the virulence of this organism for the mouse, we have investigated the frequency and characteristics of haemolysin production in clinical isolates of this and all other species in the Proteeae to see if the virulence of P. mirabilis for the urinary tract is likely to be similarly linked to haemolysin production.…”