Studies of the cultivable flora of normal human feces

Highly diluted feces, obtained from healthy adult individuals, was plated on blood-agar plates which were incubated both aerobically and anaerobically. From the anaerobic plates containing 30 to 60 colonies, every colony was subcultured. Nearly all isolates were obtained in pure culture and partially characterized. It was found thatBacteroides species were the most predominant organisms, being present in numbers approximating 10¹⁰ per gram wet weight. Selected bacteria present in lower numbers were determined by plating appropriate dilutions of feces on selective media. It was found that coliforms, streptococci and lactobacilli were regularly present in concentrations of 10⁶ ? 10⁸ organisms per gram wet weight material, whileVeillonella, Streptococcus salivarius, Bacteroides melaninogenicus and staphylococci were present in lower numbers. Fusobacteria were only found in one sample, whileNeisseria were not detected in any of the samples. Wet mounts of fecal material, inspected by darkfield microscopy, did not reveal the presence of spirochetes. Anaerobes outnumbered facultative bacteria by a factor of 40, indicating that the human adult fecal flora is predominantly anaerobic. Total microscopic counts indicate that bacteria comprise approximately 30% of the mass of human feces.     

Immunofluorescent evidence of Proteus mirabilis swarm cell formation on sterilized rat feces.

Swarming Proteus spp. were detected with the use of proteometry (a most-probable-number technique) in the fecal material of selected animal species and in raw sewage from a local sewage treatment plant. Proteus spp. were not detected in any of several soil and freshwater samples examined. Since rat feces harbored high numbers of Proteus mirabilis compared with other habitats examined, we chose to examine it for the possibility of supporting swarming. Immunofluorescent studies with a strain-specific conjugate revealed the morphogenesis of short forms into elongated swarm cells upon the surface of sterilized rat feces that had been inoculated with short forms of P. mirabilis. the same phenomenon was not observed consistently when nonsterile rat feces were inoculated and examined with immunofluorescence.     

R-Factor-Mediated Resistance to Tetracycline in Proteus mirabilis

The expression of R-factor-mediated resistance to tetracycline has been compared in Proteus mirabilis and Escherichia coli. Resistance to a range of concentrations of tetracycline was significantly lower in P. mirabilis than in E. coli in both induced and repressed states. Indirect evidence showed that conditions which result in a marked increase in the level of resistance of P. mirabilis harboring the R factor NR1 to chloramphenicol, streptomycin, and spectinomycin due to an amplification in the number of copies of r-determinants per cell do not detectably increase the level of resistance to tetracycline. Tetracycline resistance was inducible in early stationary-phase P. mirabilis NR1 although not after 5 h in this state. Double isotope labeling of control and tetracycline-induced P. mirabilis NR1 in early stationary phase revealed isotopic enrichment of certain peaks in extracts from induced cells subjected to polyacrylamide gel electrophoresis.     

Biosynthesis of Proteus mirabilis Nuclease

The culture liquid and periplasm of Proteus mirabilis contained nuclease, an enzyme with DNase and RNase activities. The nuclease was most actively synthesized in the early exponential and stationary growth phases. Nuclease synthesis was regulated by nucleic acids (induction by substrate) and inorganic phosphate (end-product inhibition). The synthesis and secretion of nuclease by P. mirabilis was induced by mitomycin C, an inducer of the SOS functions of cells. This suggests the involvement of SOS-response proteins in the regulation of nuclease synthesis.     

The phospholipases of Proteus mirabilis

The method of screening Proteus for phospholipase activity has been worked out. The study of isolated clones of the same strain, used as an example, has revealed that clones differing in their phospholipase activity also differ in virulence and in some parameters of interaction in the host-parasite system. P. mirabilis phospholipases are supposed to be of importance as one of the factors contributing to the invasive properties of these microorganisms at the stage of overcoming the epithelial cell barrier of mucous membranes.     

Response of Blood Platelets to Proteus mirabilis Lipopolysaccharide

The effects of the lipopolysaccharide (LPS) of Proteus mirabilis on the production of thiobarbituric acid reactive substances (TBARS) and the generation of superoxide radicals (O₂^?) by pig blood platelets were studied in vitro. The effect of LPS on TBARS formation in platelets was dependent on the concentration of endotoxin. LPS at concentrations above 0.1 μg/10⁸ platelets caused the production of TBARS concomitant with the generation of superoxide radicals. The responses of platelets to LPS suggest that endotoxin, like thrombin (a strong platelets agonist), stimulates an enzymatic cascade of platelet arachidonate via cyclooxygenase and produces thromboxane A₂ (TXA₂) concomitant with malonyldialdehyde (MDA).     

Fimbriae of uropathogenic Proteus mirabilis

Proteus mirabilis is a common causative agent of cystitis and pyelonephritis in patients with urinary catheters or structural abnormalities of the urinary tract. Several types of fimbriae, which are potentially involved in adhesion to the uroepithelium, can be expressed simultaneously by P. mirabilis: mannose-resistant/Proteus-like (MR/P) fimbriae, P. mirabilis fimbriae (PMF), uroepithelial cell adhesin (UCA), renamed by some authors nonagglutinating fimbriae (NAF), and ambient-temperature fimbriae (ATF). Proteus mirabilis is a common cause of biofilm formation on catheter material and MR/P fimbriae are involved in this process. The considerable serious pathology caused by P. mirabilis in the urinary tract warrants the development of a prophylactic vaccine, and several studies have pointed to MR/P fimbriae as a potential target for immunization. This article reviews P. mirabilis fimbriae with regard to their participation in uropathogenesis, biofilm formation and as vaccine targets.     

Characterization of Indole-Positive Proteus mirabilis

Thirteen indole-producing, swarming strains of Proteus were identified by additional biochemical testing as being Proteus mirabilis. These strains were characterized by 40 biochemical tests and by susceptibility testing to 11 antibiotics. All produced ornithine decarboxylase and were susceptible to members of the penicillin-cephalosporin groups of antibiotics. These indole-positive strains are similar to indole-negative P. mirabilis and are distinctly different from P. vulgaris. For greatest accuracy and to insure greatest clinical relevancy, P. mirabilis and P. vulgaris should be distinguished from one another in the laboratory by performing both the indole and ornithine decarboxylase tests.     

Biosynthesis of Proteus mirabilis nuclease

The culture liquid and periplasm of Proteus mirabilis contained nuclease, an enzyme with DNase and RNase activities. The nuclease was most actively synthesized in the early exponential and stationary growth phases. Nuclease synthesis was regulated by nucleic acids (induction by substrate) and inorganic phosphate (end-product inhibition). The synthesis and secretion of nuclease by P. mirabilis was induced by mitomycin C, an inducer of the SOS functions of cells. This suggests the involvement of SOS-response proteins in the regulation of nuclease synthesis.     

Transposon mutagenesis in Proteus mirabilis.

A technique of transposon mutagenesis involving the use of Tn5 on a suicide plasmid was developed for Proteus mirabilis. Analysis of the resulting exconjugants indicated that Tn5 transposed in P. mirabilis at a frequency of ca. 4.5 x 10(-6) per recipient cell. The resulting mutants were stable and retained the transposon-encoded antibiotic resistance when incubated for several generations under nonselective conditions. The frequency of auxotrophic mutants in the population, as well as DNA-DNA hybridizaiton to transposon sequences, confirmed that the insertion of the transposon was random and the Proteus chromosome did not contain significant insertional hot spots of transposition. Approximately 35% of the mutants analyzed possessed plasmid-acquired ampicillin resistance, although no extrachromosomal plasmid DNA was found. In these mutants, insertion of the Tn5 element and a part or all of the plasmid had occurred. Application of this technique to the study of swarmer cell differentiation in P. mirabilis is discussed.     

人工饲养幼猴粪便的正常菌群研究

目的通过对10只幼猴粪便正常菌群的测定,了解幼猴肠道正常菌群的分布情况,为猕猴肠道疾病的治疗和微生态制剂的开发提供一定理论依据.方法用微生态学检测方法,对10只健康幼猴粪便中正常菌群(9种细菌)进行定性、定量分析.结果在健康幼猴肠道中,双歧杆菌(10.02±0.25)、类杆菌(10.00±0.09)、韦荣球菌(9.96±0.31)、肠球菌(9.98±0.43)和梭杆菌(9.90±0.24)为优势菌群,而肠杆菌(7.32±1.49)、葡萄球菌(5.74±0.49)和酵母菌(5.42±1.47)含量则较少.结论该实验测出健康幼猴粪便内正常菌群值可作为健康幼猴肠道内正常菌群值的参考.