A new bacteriophage typing scheme forProteus mirabilis andProteus vulgaris strains

The lytic properties of 21 bacteriophages constituting a new typing set forProteus were examined in 507Proteus mirabilis and 29P. vulgaris strains isolated from patients and healthy subjects. Comparison of their morphological, serological, genetic and lytic properties showed that, in theMyoviridae andPodoviridae families, some phages were so closely related that the presence of all of them in the set was redundant. Analysis of the lytic properties revealed that some of the bacteriophages were not active enough to facilitate the differentiation ofProteus strains The size of the final typing set was reduced from 21 to 12 phages but it was suggested that, in order to improve the differentiation capacity of the set, new phages should be included. Second part:Folia Microbiol. 41, 137–140 (1996).     

A new phage typing scheme forProteus mirabilis andProteus vulgaris strains

A new bacteriophage typing set, composed of 22 phages, was established as a tool for differentiation ofProteus strains. All the phages were tailed and included 4 morphological types (A1, A2, B1 and C1). They were classified into the familiesMyoviridae, Siphoviridae andPodoviridae. From the set, 19 phages had double-stranded DNA and 3 were single-stranded DNA phages.     

Envelope structure in three different L-forms ofProteus mirabilis

One A-type, stable and two different B-type, unstable L-forms were obtained from a strain ofProteus mirabilis and studied by electron microscopy and by chemical analysis for the presence of peptidoglycan. The wall of the parent bacterium is characterized by a profile of three superimposed dense lines and a content of 11.07 nmoles of muramic acid (MUR) and of 7.85 nmoles of diaminopimelic acid (DAP) per mg of dry weight. The stable, A-type L-form has completely lost the cell wall of the bacterium and is enveloped only by the plasma membrane to which very small quantities of peptidoglycan components are associated (MUR: 0.041 nmoles/mg; DAP: 0.075 nmoles/mg). The two B-type, unstable L-forms have the same wall structure in only two dense lines, but they differ in their peptidoglycan content. The first one does not contain more peptidoglycan components than the A-type, L-form (MUR: 0.022 nmoles/mg; DAP: 0.016 nmoles/mg), whereas the peptidoglycan content of the second one (MUR: 2.6 nmoles/mg; DAP: 1.65 nmoles/mg) is about one fifth of the content of muramic acid and diaminopimelic acid of the bacterial cell wall.     

Adhesion of canine and human uropathogenicEscherichia coli andProteus mirabilis strains to canine and human epithelial cells

Escherichia coli strains causing urinary tract infections in dogs produce fimbriae composed of fimbrial subunits closely related to the F12 and F13 fimbriae of human uropathogenic strains [4]. The adhesins carried by the fimbriae of human and canine isolates differ, however, as concluded from a different hemagglutination pattern and from the fact that the dog strains do not agglutinate latex beads coated with P-fimbriae receptor. This possible difference in adhesive specificity was confirmed by experiments in which the adhesion of human and dog isolates to dog kidney epithelial cells (MDCK cells) and human bladder epithelial cells (T24 cells) was compared. Dog uropathogenic strains, in contrast to human uropathogenicE. coli strains, adhere to MDCK cells but hardly to T24 cells. Adhesion to MDCK cells correlates with the presence of F12 or F13 fimbriae on the dog strains. These results suggest that homologous fimbrial subunits can carry different adhesin molecules and that these adhesin molecules can be responsible for species-specific adherence. On the contrary, adhesion of a number of dog uropathogenicProteus mirabilis strains to MDCK and T24 cells was not species specific; it depended on the mere presence of fimbriae.     

Effect of ionizing radiation on large bodies ofProteus vulgaris

Proteus vulgaris (Штамм P₂) весьма устойчив к облучению. Средней летальной дозой оказалось облучение 10 000 r. Крупнье круглые тельца, образующиеся под действием, пенициллина, так зе чувствительны к рентгеновскому облучению, как палочки. После облучения, уже начиная с дозы в 5–10 тысяч r, набльдалось слияние нуклеоидов (ядерных эквивалентов) подобно тому, как под действием охлаждения до 6° C. В среде без солей это явление не наблюдалось.     

Fatty acid composition of membranes of L-forms ofStreptococcus faecalis andProteus mirabilis cultured at different osmolalities

The fatty acid composition of membranes of L-forms ofStreptococcus faecalis andProteus mirabilis cultured at different osmolalities and in different osmotic stabilizers was examined.S. faecalis L-forms cultured with sucrose in the medium showed a decrease in the unsaturated fatty acid C₁₈₁ and an increase in the C₁₈ fatty acid and C₁₉ cyclopropane fatty acid. Fatty acid composition ofS. faecalis L-forms cultured in medium containing 1.8% NaCl was similar to the fatty acid composition of L-forms cultured in brain-heart infusion broth (BHI) without osmotic stabilizer and was between the composition of fatty acids of L-forms in BHI with sucrose and that in BHI without 0.5 M sucrose. InProteus mirabilis L-forms, there were differences between L-forms cultured with and without sucrose, but these differences were not comparable to the changes observed inS. faecalis L-forms.P. mirabilis L-forms cultured with and without NaCl in the medium had similar fatty acid compositions.     

Effects of some tricyclic psychopharmacons and structurally related compounds on motility ofProteus vulgaris

A simple test for the evaluation of drugs interfering with bacterial motility was established withProteus vulgaris. With this model, promethazine, 7-hydroxy-chlorpromazine, imipramine, 7,8-dioxochlorpromazine and acridine orange were shown to exert significant motility and swarming inhibitory action onProteus vulgaris strains at subinhibitory concentrations. Quinidine enhanced the antimotility effect of promethazine. The antimotility effect of promethazine was synergized by proton pump inhibitors omeprazole and abscissic acid, but antagonized by extracellular potassium and sodium ions.     

Electron microscopy of the localization of formic dehydrogenase in regenerating forms ofProteus vulgaris

The localization of the formic dehydrogenase system was studied by means of nitro-blue tetrazolium, using the ultrathin section technique, in large long bodies ofProteus vulgaris, which form the intermediate stage in regeneration of penicillin-induced spheroplasts. In the electron microscope, empty areas, numbering on an average four per cell section, were found at the site of formazan deposits, while in the controls (without tetrazolium salts) the average number was 0.05. From these findings, and from the findings of other authors showing that formic dehydrogenase is bound to cell structures, it can be concluded that inProteus cells this enzyme is bound to the cytoplasmic membrane.     

Some biological features of Proteus bacilli. 2. Haemolytic activities of Proteus mirabilis and Proteus vulgaris strains

The haemolytic activities of Proteus mirabilis and P. vulgaris strains were studied under different conditions. No filterable alpha haemolysin could be detected in P. mirabilis uropathogens provided from patients with urinary tract infections. Together with the results presented in the accompanying paper, in which three clinical isolates with temporary ability to produce a soluble haemolysin were described, the occurrence of alpha haemolytic P. mirabilis isolates did not exceed 3%. Cell bound beta haemolysin is present in nearly 35% of P. mirabilis urinary strains. Another kind of haemolytic activity was observed when P. mirabilis and P. vulgaris strains were grown in liquid media supplemented with erythrocytes. During the logarithmic growth phase nearly 100% of P. mirabilis and P. vulgaris strains of various origin haemolyzed 100-50% of erythrocytes. Except for Serratia, the other representatives of Enterobacteriaceae did not demonstrate such activity in the same conditions. The preliminary characteristics of this phenomenon is given.     

O-serogrouping scheme for mesophilic Aeromonas strains

The O-antigens of 307 strains of mesophilic Aeromonas including 227 A. hydrophila and 80 A. caviae were studied and 44 O-serogroups defined among them. The presence of heat-labile masked antigen, which inhibits O-agglutination, was observed in some strains. As all the O-antisera prepared with these mesophilic Aeromonas strains contained some R-antibody, all diagnostic O-antisera must be absorbed with R-organisms before use. Some of the O-antigens were found to be identical or closely related to those of certain serovars of Vibrio cholerae, Vibrio fluvialis or Plesiomonas shigelloides.     

Tests for studying invasive properties of selected Proteus mirabilis strains]

Proteus mirabilis is an important pathogen of the urinary tract infections (UTI). Lipopolysaccharide (LPS, endotoxin) is one of the pathogenic factors of pathogenicity of these bacteria. In this paper we described the invasion of L929 mouse fibroblasts by P. mirabilis strains, classified into the O10, O23, O30, O43 serogroups. The maximal invasiveness was observed between 4-6 hours of incubation of the tested cells with bacteria. The cytotoxic effect slightly increased with the incubation time, probably as a result of the production of HpmA hemolysin. Incubation of L929 fibroblasts with LPS led to decrease of bacterial invasiveness. We observed that with the time of incubation of L929 cells with LPS (2-22 h), the invasiveness decreased (longer incubation time with LPS--weaker penetration).     

Production of superoxide dismutases from Proteus mirabilis and Proteus vulgaris

Proteus mirabilis and Proteus vulgaris expressed a combination of superoxide dismutase (Sod) activities, which was assigned to FeSod1, FeSod2 and MnSod for P. mirabilis, and FeSod, MnSod and CuZnSod for P. vulgaris. Production of the Sod proteins was dependent on the availability of iron, whether cells were grown under anaerobiosis or aerobiosis and growth phase. Nalidixic acid and chloramphenicol inhibited cell growth and the iron- and dioxygen-dependent production of Sod. These results support the involvement of metal ions and redox status in the production of Proteus Sods.     

Proposal of a new scheme for the serological typing of Enterococcus faecalis strains.

No systematic study on serotyping of Enterococcus faecalis has been reported since 1964 when M.E. Sharpe conducted serotyping of group D streptococcus in U.K. So, we attempted to re-evaluate serotyping of E. faecalis. For this purpose, we received 42 Sharpe's strains and first examined for their biochemical characteristics as E. faecalis. Only 9 of the 42 strains were identified as E. faecalis. We raised rabbit antisera against a large number of E. faecalis strains, including the 9 Sharpe's strains, 2 strains obtained from CDC in U.S.A. and 36 strains isolated from patients hospitalized in different cities of Japan. From the results of cross-agglutination tests and absorption tests performed on these antisera using a large number of E. faecalis strains, we were able to classify 21 distinct serotype strains and to prepare 21 monospecific typing antisera by absorption of the antisera to the type strains with appropriate cross-agglutinating strains. When 832 E. faecalis strains were serotyped with the 21 typing antisera, 638 strains (76.7%) were typable. Thus, we propose a provisional scheme of 21 distinct serovars in E. faecalis.     

Ultrastructural characteristics of Proteus vulgaris and Proteus mirabilis cells differing in the capacity for swarming

Specific differences in the structure of colonies and the location of microbial cells in colonies, characteristic for aggregating and nonaggregating genetically related pairs of P. vulgaris and P. mirabilis strains, have been demonstrated by means of transmission and scanning electron microscopy. In calculating the number of flagellae per 100 outlines of microbial bodies revealed in negatively stained preparations, the fact that both aggregating and nonaggregating bacteria possess practically the same number of flagellae, on the average 4-8 flagellae per microbial cell outline, has been established. This fact indicates that the presence of flagellae in microbial cells is unrelated to their capacity for swarming.