Masatoshi Fujihara

Hemotropic mycoplasma infection in wild black bears (Ursus thibetanus japonicus)

This is the first report on Mycoplasma infection in wild bears. We report a novel hemotropic Mycoplasma (also called hemoplasma) detected in a free-ranging black bear (Ursus thibetanus japonicus) in Japan. We then used real-time PCR to look for hemoplasma DNA in blood samples collected from 15 bears and found that eight (53%) were positive. Among these eight PCR samples, seven showed a melting temperature of around 85.5°C, while the remaining one showed a single peak at 82.26°C. Almost the entire region of the 16S rRNA gene as well as the 16S-23S rRNA intergenic transcribed spacer (ITS) region from the sample that showed a melting temperature of 82.26°C was successfully amplified by means of end-point PCR. The nucleotide sequences of the 16S rRNA gene and the ITS region were then determined and compared with those of authentic Mycoplasma species. Our examinations revealed the presence of a novel hemoplasma in Japanese black bears.

Acidic environments induce differentiation of Proteus mirabilis into swarmer morphotypes

Although swarmer morphotypes of Proteus mirabilis have long been considered to result from surfaced‐induced differentiation, the present findings show that, in broth medium containing urea, acidic conditions transform some swimmer cells into elongated swarmer cells. This study has also demonstrates that P. mirabilis cells grown in acidic broth medium containing urea enhance virulence factors such as flagella production and cytotoxicity to human bladder carcinoma cell line T24, though no significant difference in urease activity under different pH conditions was found. Since there is little published data on the behavior of P. mirabilis at various hydrogen‐ion concentrations, the present study may clarify aspects of cellular differentiation of P. mirabilis in patients at risk of struvite formation due to infection with urease‐producing bacteria, as well as in some animals with acidic or alkaline urine.

Salivary nitrate and nitrite may have antimicrobial effects on Desulfovibrio species.

The antibacterial effects of salivary nitrate/nitrite on the growth of three Desulfovibrio species were examined. The bacteria did not grow on plates with ≥0.2 mM nitrate or ≥1.0 mM nitrite. They were also incubated in filter-sterilized saliva. D. desulfuricans was reduced on the order of >102 compared with the control solution (phosphate-buffered saline) in nine out of the 10 participants.

Growth kinetics of Salmonella enterica in Hajna tetrathionate broth, Rappaport broth and modified semisolid Rappaport agar.

To determine the appropriate method for isolating Salmonella enterica, we compared the growth of S. enterica serovars using three selective enrichment media. S. enterica was more successfully isolated from artificially contaminated fecal samples after enrichment in Hajna tetrathionate broth or modified semisolid Rappaport agar than in Rappaport broth. Since most bacteria (other than motile S. enterica) do not migrate on modified semisolid Rappaport agar, the growth characteristics of S. enterica can be interpreted easily and quickly. Two S. enterica isolates did not migrate on modified semisolid Rappaport agar, but did grow in Hajna tetrathionate broth, which suggests that the combined use of these selective enrichment media is appropriate for isolating S. enterica.

Effects of urea on length distribution and morphology of Escherichia coli and Salmonella enterica subsp. enterica cells

1 Laboratory of Veterinary Microbiology, Iwate University, 3-18-8 Ueda, Morioka, Iwate 020-8550, Japan. 2 The United Graduate School of Veterinary Science, Gifu University, 1-1 Yanagido, Gifu, Gifu 501-1193, Japan. 3 Department of Physics, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551, Japan. 4 Laboratory of Veterinary Anatomy, Iwate University, 3-18-8 Ueda, Morioka, Iwate 020-8550, Japan.

Identification and phase inversion of Salmonella flagellar antigens, using immuno-discs

Disc immuno-immobilization is a simple method for typing the flagellar phase of Salmonella enterica. We re-examined this method using commercial antisera, which contains the preservative sodium azide. Originally prepared motility agar activates bacterial motility and renders S. enterica resistant to sodium azide, resulting in the formation of immuno-immobilization lines around reactive immuno-discs. Though disc immuno-immobilization serves both serotyping and phase inversion, this method is insufficient for the strains in which phase variation rarely occurs. Here, we devised a novel immuno-disc phase inversion method, and all S. enterica strains tested were identically typed. These methods would drastically simplify the task of S. enterica typing in clinical laboratories.

The bacterial cell division protein FtsZ forms rings in swarmer cells of Proteus mirabilis

Bacterial FtsZ assembles and constricts after chromosomal segregation in the course of cell division. Here we examined the localization of FtsZ in multinucleated swarmer cells of Proteus mirabilis by immunostaining. FtsZ was found to localize to the point of karyomitosis in swarmer cells of P. mirabilis, which is equivalent to filamentous mutants of Escherichia coli defective in the ftsI or ftsQ genes that are involved in later steps of cell division. Thus our findings suggest that the appearance of swarmer cells results from cellular functions immediately after FtsZ assembly.