[Ecology and significance of the Proteus group]

Tissue-binding affinity of Proteus mirabilis fimbriae in the human urinary tract

Binding characteristics of the two major fimbrial hemagglutinin types of uropathogenic Proteus mirabilis were determined in frozen sections of human kidney and in exfoliated uroepithelial cells. P. mirabilis 3087, which expresses the MR/P fimbriae, adhered avidly to the tubular epithelial cells of the kidney and also to the epithelial cells of urinary sediment. No adhesion to glomerular or peritubular elements of the kidney was detected. Indirect immunogold silver staining also showed that the purified MR/P fimbriae recognized the same kidney domains. Adhesion of strain 3087 to uroepithelial cells was completely inhibited by Fab fragments of antibodies against the purified MR/P fimbriae. A completely different tissue-binding pattern was exhibited by the MR/K fimbriae of P. mirabilis 2456. In the kidney, the MR/K fimbriae bound strongly to the Bowman's capsule of the glomeruli and to the tubular basement membranes. A weak binding to glomerular mesangium and tubular epithelial cells was also seen. Strain 2456 did not adhere to epithelial cells of urinary sediment. Analysis of normal human urine showed that it contains low-molecular-weight molecules capable of inhibiting the binding of the MR/P fimbriae; no urinary inhibitors could be detected for the MR/K fimbriae. Poor in vivo binding capacity to intact human uroepithelial cells may be an important factor in explaining the relatively low pathogenicity of P. mirabilis in healthy hosts.

Attachment of Proteus mirabilis to human urinary sediment epithelial cells in vitro is different from that of Escherichia coli

The in vitro attachment of 335 Proteus mirabilis strains from various human sources to human urinary tract epithelial cells was measured. No significant difference in adhesive capacity was found between P. mirabilis strains isolated from the blood of 89 patients with bacteremia, the stools of 36 healthy subjects and 56 patients with diarrhea, and the urine of 62 adults and 92 children with bacteriuria. High mean adhesion values were observed in all groups. The P. mirabilis strains attached only to squamous cells and not to transitional epithelial cells, whereas most of the Escherichia coli strains tested attached to both cell types; strains from patients with acute pyelonephritis attached more often than those from patients with acute cystitis or asymptomatic bacteriuria. The attachment of P. mirabilis to squamous epithelial cells was high about day 15 of the menstrual cycle of the epithelial cell donor, but low at the beginning and the end of the cycle. In contrast, the attachment of E. coli to squamous and transitional epithelial cells did not vary significantly with the menstrual cycle of the cell donor. Differences in adhesion characteristics of E. coli and P. mirabilis may relate to the differences in clinical appearance of urinary tract infections produced by the two organisms.

Correlation of the characters fermentation of trehalose, non-transmissible resistance to tetracycline, and relatively long flagellar wavelength in Proteus morganii

An investigation of strains of Proteus morganii isolated from patients in Odense, Denmark, and of 21 serotype strains revealed a close correlation between the fermentation of trehalose and a non-transmissible resistance to tetracycline. The trehalose fermenting, tetracycline resistant strains had a longer flagellar wavelength than the non-fermenting, sensitive strains. Resistance to chloramphenicol occurred only in strains of the former group.

Sensitivity of Providence to antiseptics and disinfectants

Seventy isolates of Providence were obtained from urinary tract infections in patients from five hospitals. They were all identified as Providence B (Providencia stuartii). A typing system was devised for these organisms based on their production of and sensitivity to bacteriophage and bacteriocins. Using this system, 27 distinct strains were recognized, and it was clear that many patients had been infected with the same strain. The minimum inhibitory concentrations of six antiseptics and disinfectants for these strains were determined. Many of the strains were up to 300-fold more resistant to the cationic antiseptics chlorhexidine, cetrimide, and Resiguard than the control strain Escherichia coli NCTC 10418. The sensitivities of the Providence strains to Hycolin, glutaraldehyde, and phenyl mercuric nitrate, however, were similar to those of the control organism. There were significant correlations between the sensitivities of the strains to the three cationic antiseptics. The loss of chlorhexidine resistance from a Providence strain after exposure of the cells to N-methyl-N' nitro N nitrosoguanidine resulted in a concomitant loss of resistance to cetrimide and Resiguard, but there was no significant increase in the sensitivity of the mutants to the other three antibacterials.

Identification of Enterobacteriaceae in the clinical microbiology laboratory

A total of 5,137 enterobacterial clinical isolates were examined with three series of biochemical tests. The data were analyzed with respect to the use of economical and practical procedures for the accurate identification of lactose-fermenting and -nonfermenting Enterobacteriaceae within 24 hr after isolation.