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Volume 69 (2014)
- Issue 4 Pages 547-
- Issue 3 Pages 479-
- Issue 2 Pages 313-
Volume 69, Issue 4
Displaying 1-6 of 6 articles from this issue
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Kouji KIMURA2014 Volume 69 Issue 4 Pages 547-555
Published: November 28, 2014
Released on J-STAGE: November 28, 2014
JOURNAL FREE ACCESSGroup B Streptococcus (GBS, Streptococcus agalactiae) is the cause of neonatal sepsis and meningitides. Moreover, this bacterium causes invasive infections to elderly people and patients suffering from diabetes et al. All clinical isolates of GBS, similar to other β-hemolytic streptococci, have been considered to be uniformly susceptible to β-lactams since 1940s, when penicillin was introduced to clinical setting. However, we analyzed clinical isolates of group B streptococci with reduced penicillin susceptibility (PRGBS), recovered in Japan during 1995–2005, and established their existence. Moreover, we promote series of studies concerning PRGBS. In this review, we describe series of studies concerning PRGBS.View full abstractDownload PDF (1753K) -
Daisuke SHIOMI2014 Volume 69 Issue 4 Pages 557-564
Published: November 28, 2014
Released on J-STAGE: November 28, 2014
JOURNAL FREE ACCESSBacteria show various cell shape such as round, rod, helical, and so on. However, each bacterium has its own shape and their length and width are kept in a narrow range in a population. Abnormal cell shape often results in death of the cells. Therefore, it is important to maintain their shape. Rod-shaped bacterium Escherichia coli needs to regulate cell polarity, length and width in order to form rod shape. Bacterial shape is genetically regulated. Especially, MreB, a bacterial actin, and its interacting proteins are involved in the regulation. We have identified rodZ as a novel cell shape determinant and have been analyzing RodZ protein in the past few years. The rodZ mutant is round. We isolated suppressor mutants of the rodZ mutant. The shape of the suppressors was rod shape. By analyzing the rodZ mutant and the suppressors, we concluded that RodZ helps assembly of MreB filaments. MreB plays roles in regulation of cell polarity, length, and width, whereas RodZ is involved in regulation of length and width. In this review, I summarize our research and research from other groups on bacterial cell shape.View full abstractDownload PDF (1504K) -
Study of infection strategies of Helicobacter pylori and host cell response against CagA oncoproteinHitoshi TSUGAWA2014 Volume 69 Issue 4 Pages 565-575
Published: November 28, 2014
Released on J-STAGE: November 28, 2014
JOURNAL FREE ACCESSChronic infection with Helicobacter pylori is involved in a variety of clinical outcomes including gastric cancer. In the present study, we focused on the infection strategies of H. pylori associated with establishment of chronic infection. As a result, the following four findings revealed. 1) alpha-ketoglutarate oxidoreductase (KOR) is an essential survival enzyme for energy metabolism in the coccoid form of H. pylori, and inactivation of the KOR activity exerted a potent bactericidal action against H. pylori by preventing induction of the coccoid form. 2) SodB expression is derepressed by amino acids mutation of ferric uptake regulator (Fur), which is associated with the development of Metronidazole resistance. 3) FecA1 is an important determinant of the host-colonization ability through Fe2+ supply to SodB, suggesting that FecA1 may be a possible target for the development of a novel bactericidal drug. 4) Intracellular CagA oncoprotein is degraded by autophagy and therefore short lived. However, in the CD44v9-expressing gastric cells, CagA specifically accumulated through the repression of autophagy induction.View full abstractDownload PDF (4914K) -
Tsuyoshi MIKI2014 Volume 69 Issue 4 Pages 577-588
Published: November 28, 2014
Released on J-STAGE: November 28, 2014
JOURNAL FREE ACCESSChromobacterium violaceum is a Gram-negative bacterium that infects humans and animals with fatal sepsis. The infection with C. violaceum is rare in case of those who are healthy, but once established, C. violaceum causes sever disease accompanied by abscess formation in the lungs, liver and spleen. Furthermore, C. violaceum is resistant to a broad range of antibiotics, which in some cases renders the antimicrobial therapy for this infection difficult. Thus, the infection with C. violaceum displays high mortality rates unless initial proper antimicrobial therapy. In contrast, the infection mechanism had completely remained unknown. To this end, we have tried to identify virulence factors-associated with C. violaceum infection. Two distinct type III secretion systems (TTSSs) were thought to be one of the most important virulence factors, which are encoded by Chromobacterium pathogenicity island 1/1a and 2 (Cpi-1/-1a and -2) respectively. Our results have shown that Cpi-1/-1a-encoded TTSS, but not Cpi-2, is indispensable for the virulence in a mouse infection model. C. violaceum caused fulminant hepatitis in a Cpi-1/-1a-encoded TTSS-dependent manner. We next have identified 16 novel effectors secreted from Cpi-1/-1a-encoded TTS machinery. From these effectors, we found that CopE (Chromobacterium outer protein E) has similarities to a guanine nucleotide exchange factor (GEF) for Rho GTPases. CopE acts as GEF for Rac1 and Cdc42, leading to induction of actin cytoskeletal rearrangement. Interestingly, C. violaceum invades cultured human epithelial cells in a CopE-dependent manner. Finally, an inactivation of CopE by disruption of copE gene or amino acid point mutation leading to loss of GEF activity attenuates significantly the mouse virulence of C. violaceum. These results suggest that Cpi-1/-1a-encoded TTSS is a major virulence determinant for C. violaceum infection, and that CopE contributes to the virulence in part of this pathogen.View full abstractDownload PDF (7472K)
Review
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Mitsumasa SAITO, Sharon Y. A. M. VILLANUEVA, Toshiyuki MASUZAWA, Yasut ...2014 Volume 69 Issue 4 Pages 589-600
Published: November 28, 2014
Released on J-STAGE: November 28, 2014
JOURNAL FREE ACCESSThis year, 2014, marks the centennial of the discovery of Leptospira as the Weil’s disease pathogen by Ryokichi Inada, Yutaka Ido and their colleagues. Leptospirosis is a worldwide zoonosis especially in countries with tropical and subtropical climates. Recently, the number of patients with leptospirosis dramatically decreased in Japan because public hygiene has greatly improved, the mechanization of agriculture was introduced, and farmers started using rubber boots and gloves while working in the field. The opportunities for percutaneous infection with Leptospira was reduced, but have not been totally eliminated in Japan.
We previously reported a novel combination of five antimicrobial agents for selective isolation of Leptospira from contaminated samples. This cocktail, after being incorporated into Leptospira growth medium, inhibited the growth of contaminants and allowed successful detection of leptospires in environmental samples. We collected soil and environmental water and cultured them using this selective medium. It was revealed that not only saprophytic Leptospira but also pathogenic Leptospira are widely living in the environment. We hypothesized that soil serves as reservoir for Leptospira and infectious source for leptospirosis. In this review, we also discuss the Leptospira-rat-human relationship in the Philippines, natural defense of host against oral and percutaneous infection by Leptospira, the mechanism of jaundice in leptospirosis, and the development of immunochromatography-based methods for detection of leptospiral antigen in urine.View full abstractDownload PDF (4622K)
Errata
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2014 Volume 69 Issue 4 Pages 601
Published: 2014
Released on J-STAGE: December 24, 2014
JOURNAL FREE ACCESSDownload PDF (480K)
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