Biomedical subjects

Teruo Kirikae

Publications and source records attributed to Teruo Kirikae.

At least 19 recordsLinked to original sources

PubMed2006

Outbreaks of multidrug-resistant Pseudomonas aeruginosa in community hospitals in Japan.

We previously reported an outbreak in a neurosurgery ward of catheter-associated urinary tract infection with multidrug-resistant (MDR) Pseudomonas aeruginosa strain IMCJ2.S1, carrying the 6'-N-aminoglycoside acetyltransferase gene [aac(6')-Iae]. For further epidemiologic studies, 214 clinical isolates of MDR P. aeruginosa showing resistance to imipenem (MIC >or= 16 microg/ml), amikacin (MIC >or= 64 microg/ml), and ciprofloxacin (MIC >or= 4 microg/ml) were collected from 13 hospitals in the same prefecture in Japan. We also collected 70 clinical isolates of P. aeruginosa that were sensitive to one or more of these antibiotics and compared their characteristics with those of the MDR P. aeruginosa isolates. Of the 214 MDR P. aeruginosa isolates, 212 (99%) were serotype O11. We developed a loop-mediated isothermal amplification (LAMP) assay and a slide agglutination test for detection of the aac(6')-Iae gene and the AAC(6')-Iae protein, respectively. Of the 212 MDR P. aeruginosa isolates, 212 (100%) and 207 (98%) were positive in the LAMP assay and in the agglutination test, respectively. Mutations of gyrA and parC genes resulting in amino acid substitutions were detected in 213 of the 214 MDR P. aeruginosa isolates (99%). Of the 214 MDR P. aeruginosa isolates, 212 showed pulsed-field gel electrophoresis patterns with >or=70% similarity to that of IMCJ2.S1 and 83 showed a pattern identical to that of IMCJ2.S1, indicating that clonal expansion of MDR P. aeruginosa occurred in community hospitals in this area. The methods developed in this study to detect aac(6')-Iae were rapid and effective in diagnosing infections caused by various MDR P. aeruginosa clones.

Acetyltransferases↗

PubMed2006

Detection of multidrug resistance in Mycobacterium tuberculosis.

We developed a DNA sequencing-based method to detect mutations in the genome of drug-resistant Mycobacterium tuberculosis. Drug resistance in M. tuberculosis is caused by mutations in restricted regions of the genome. Eight genome regions associated with drug resistance, including rpoB for rifampin (RIF), katG and the mabA (fabG1)-inhA promoter for isoniazid (INH), embB for ethambutol (EMB), pncA for pyrazinamide (PZA), rpsL and rrs for streptomycin (STR), and gyrA for levofloxacin, were amplified simultaneously by PCR, and the DNA sequences were determined. It took 6.5 h to complete all procedures. Among the 138 clinical isolates tested, 55 were resistant to at least one drug. Thirty-four of 38 INH-resistant isolates (89.5%), 28 of 28 RIF-resistant isolates (100%), 15 of 18 EMB-resistant isolates (83.3%), 18 of 30 STR-resistant isolates (60%), and 17 of 17 PZA-resistant isolates (100%) had mutations related to specific drug resistance. Eighteen of these mutations had not been reported previously. These novel mutations include one in rpoB, eight in katG, one in the mabA-inhA regulatory region, two in embB, five in pncA, and one in rrs. Escherichia coli isolates expressing individually five of the eight katG mutations showed loss of catalase and INH oxidation activities, and isolates carrying any of the five pncA mutations showed no pyrazinamidase activity, indicating that these mutations are associated with INH and PZA resistance, respectively. Our sequencing-based method was also useful for testing sputa from tuberculosis patients and for screening of mutations in Mycobacterium bovis. In conclusion, our new method is useful for rapid detection of multiple-drug-resistant M. tuberculosis and for identifying novel mutations in drug-resistant M. tuberculosis.

Antitubercular Agents↗

PubMed2006

Not lipoteichoic acid but lipoproteins appear to be the dominant immunobiologically active compounds in Staphylococcus aureus.

Lipoteichoic acid (LTA) derived from Staphylococcus aureus is reported to be a ligand of TLR2. However, we previously demonstrated that LTA fraction prepared from bacterial cells contains lipoproteins, which activate cells via TLR2. In this study, we investigated the immunobiological activity of LTA fraction obtained from S. aureus wild-type strain, lipoprotein diacylglycerol transferase deletion (delta lgt) mutant, which lacks palmitate-labeled lipoproteins, and its complemented strain and evaluated the activity of LTA molecule. LTA fraction was prepared by butanol extraction of the bacteria followed by hydrophobic interaction chromatography. Although all LTA fractions activated cells through TLR2, the LTA from delta lgt mutant was 100-fold less potent than those of wild-type and complemented strains. However, no significant structural difference in LTA was observed in NMR spectra. Further, alanylation of LTA molecule showed no effect in immunobiological activity. These results showed that not LTA molecule but lipoproteins are dominant immunobiologically active TLR2 ligand in S. aureus.

Acyltransferases↗

PubMed2006

Use of DNA arrays to identify a mutation in the negative regulator, csrR, responsible for the high virulence of a naturally occurring type M3 group A streptococcus clinical isolate.

We previously reported that type M3 group A streptococcus (GAS) showed a wide range of 50% lethal dose values in mice. Analysis using DNA arrays indicated that the most virulent strain, M3-f, expressed significantly higher levels of the products of several virulence genes than did the other M3 isolates. Sequencing of the csrS, csrR, luxS, and rgg genes in the isolates showed that the M-3f csrR gene contained a specific point mutation. Disruption of wild-type (wt) csrR in an M3 strain increased its virulence and the expression of hyaluronic acid, whereas complementation with wt but not type M3-f csrR attenuated these changes. Expression experiments showed that type M3-f CsrR counteracted the effects of wt CsrR. Although wt CsrR bound to the hasA promoter region, type M3-f CsrR did not. Thus, the high virulence of the type M3-f strain is associated with the decreased binding of type M3-f CsrR to its target sequences.

Amino Acid Sequence↗

PubMed2006

Expression, purification and crystallization of Streptococcus dysgalactiae-derived mitogen.

Superantigens are bacterial or viral toxins with potent immunostimulatory properties. Streptococcus dysgalactiae-derived mitogen, a 25 kDa protein, is a recently discovered superantigen isolated from S. dysgalactiae culture supernatant. Sequence considerations suggest that it belongs to a new superantigen family distinct from other superantigens. The protein was expressed in Escherichia coli cells and purified to homogeneity. Crystals were grown at pH 4.2-4.4 in the presence of 18-20%(w/v) PEG 3350 and 0.4 M lithium nitrate. A complete data set to 2.4 A resolution was collected from a single crystal at liquid-nitrogen temperatures using synchrotron radiation. The crystals belong to space group P3/P3(1)/P3(2), with unit-cell parameters a = b = 52.7, c = 62.4 A, gamma = 120 degrees and one molecule in the crystallographic asymmetric unit.

Crystallization↗

PubMed2006

Targeting FtsZ for antituberculosis drug discovery: noncytotoxic taxanes as novel antituberculosis agents.

Screening of 120 taxanes identified a number of compounds that exhibited significant antituberculosis activity. Rational optimization of selected compounds led to the discovery that the C-seco-taxane-multidrug-resistance (MDR) reversal agents (C-seco-TRAs) are noncytotoxic at the upper limit of solubility and detection (>80 microM), while maintaining MIC(99) values of 1.25-2.5 microM against drug-resistant and drug-sensitive strains of Mycobacterium tuberculosis (MTB). Treatment of MTB cells with TRA 3aa and 10a at the MIC caused filamentation and prolongation of the cells, a phenotypic response to FtsZ inactivation.

Actin Cytoskeleton↗

PubMed2006

Emergence of rifampicin resistance in methicillin-resistant Staphylococcus aureus in tuberculosis wards.

To assess whether the occurrence of rifampicin (RFP) resistance in methicillin-resistant Staphylococcus aureus (MRSA) is related to treatment of tuberculosis, we determined the RFP susceptibility of MRSA isolates obtained from tuberculosis patients and screened for mutation(s) in the rpoB gene of these isolates. The MICs of RFP for 84 MRSA isolates obtained from two hospitals in Japan were determined. DNA was sequenced in the region 1318-1602 nucleotides (nt) of the rpoB gene, which includes RFP resistance-determining clusters I (1384-1464 nt, 462-488 amino acids). The majority of MRSA isolates from tuberculosis wards, i.e., 48 of 51 (94%) [33 of 34 in a Tokyo hospital (97%) and 15 of 17 in a Chubu hospital (88%)], were resistant to RFP. Meanwhile, no isolates of 33 from the other wards were resistant to RFP. All RFP-resistant MRSA isolates had a mutation(s), including novel mutation(s) such as Val453-->AEPhe, Asp471-->AEAsn, and Ile527-->AELeu, in rpoB. An emergence of RFP-resistant MRSAs in tuberculosis wards in Japan was strongly suggested.

Amino Acid Sequence↗

PubMed2006

Generation and characterization of monoclonal antibodies that specifically recognize p65/L-plastin isoform but not T-plastin isoform.

The 65-kDa protein (p65) was previously identified as a phosphorylated protein in activated macrophages, and has turned out to be a member of a plastin protein family characterized by a series of Ca(2+)-, calmodulin-, and beta-actin-binding domains. In mice, two isoforms, p65/L-plastin and T-plastin, have so far been identified; p65/L-plastin is expressed in hemopoietic cells and cancer cells, and T-plastin in solid tissue cells. We generated monoclonal antibodies to p65/L-plastin, examined the isoform-specificity by using recombinant (r) T-plastin, and found that the antibodies were specific for rp65/L-plastin, whereas immune sera to rp65/L-plastin showed cross-reactions to rT-plastin. One of the antibodies, p65-7B5, was demonstrated to react to native p65/L-plastin by Western blot, flow cytometric, and immunohistochemical analysis. Furthermore, p65-7B5 has made it possible to detect p65/L-plastin-expressing cells in tissues where T-plastin is abundantly expressed. These reagents and procedures should provide specific tools to investigate the role of p65/L-plastin in leukocytes.

Animals↗

PubMed2006

"Syndromic surveillance within a hospital" for the early detection of a nosocomial outbreak of acute respiratory infection.

We have performed intra-hospital syndromic surveillance to rapidly detect nosocomial acute respiratory infection outbreaks in both inpatients and health care workers in a hospital. Syndromic surveillance allows the rapid detection of sudden outbreaks, including infections caused by unknown pathogens. This approach depends on the identification of specific "symptoms" as signs of a possible outbreak, with no need for specific diagnoses. Moreover, syndromic surveillance is quick, easy, and inexpensive. Nosocomial infection surveillance is usually performed on inpatients only. However, during the outbreaks of SARS and seasonal influenza, for example, many hospital personnel were infected. In cases of this kind, in order to quickly detect the prevalence of such infections, a surveillance system that includes hospital personnel is essential. This surveillance is promising as a strategy to prepare for re-outbreaks of SARS and the emergence of novel influenza pandemics.

Acute Disease↗

PubMed2005

Association of rpoB mutations with rifampicin resistance in Mycobacterium avium.

The susceptibility of clinical isolates of Mycobacterium avium to rifampicin (RIF) was examined. All 32 clinical isolates tested, including 18 from Japan, 13 from Poland and 1 from Thailand, were resistant to RIF (minimum inhibitory concentrations (MICs) > or =32 microg/mL for 17 isolates and 2-16 microg/mL for 15 isolates), whereas the type strain of M. avium ATCC 25291 was susceptible to RIF (MIC < or = 0.03 microg/mL). Mutations in nucleotides 1276-1356 of the rpoB gene, termed the 81 bp core region, are associated with RIF resistance in Mycobacterium tuberculosis. No mutations were found in this region in any of the M. avium clinical isolates tested. However, mutation of G-->A to give a Gly544-->Asp substitution was identified within the rpoB gene downstream of the 81 bp region in all clinical isolates. A RIF-resistant strain (ATCC 25291 Rif(r); MIC> or =32 microg/mL) obtained by culturing the type strain in RIF-containing broth possessed a mutation C-->T to give a His445-->Tyr substitution within the 81 bp region. When the rpoB gene of the ATCC 25291 Rif(r) strain and of a clinical isolate were inserted into Mycobacterium smegmatis, organisms with the ATCC 25291 Rif(r) sequence, but not those with the clinical isolate sequence, showed resistance to RIF. These results suggest that mutations of the 81 bp region of rpoB, as well as factors other than rpoB mutation, confer RIF resistance in M. avium.

Amino Acid Sequence↗

PubMed2005

Triketones active against antibiotic-resistant bacteria: synthesis, structure-activity relationships, and mode of action.

A series of acylated phloroglucinols and triketones was synthesized and tested for activity against methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus faecalis (VRE) and multi-drug-resistant Mycobacterium tuberculosis (MDR-TB). A tetra-methylated triketone with a C12 side chain was the most active compound (MIC of around 1.0 microg/ml against MRSA) and was shown to stimulate oxygen consumption by resting cell suspensions, suggesting that the primary target was the cytoplasmic membrane.

Anti-Bacterial Agents↗

PubMed2005

Identification of an alternative 5'-untranslated exon and new polymorphisms of angiotensin-converting enzyme 2 gene: lack of association with SARS in the Vietnamese population.

We analyzed genetic variations of angiotensin-converting enzyme 2 (ACE2), considering that it might influence patients' susceptibility to severe acute respiratory syndrome-associated coronavirus (SARS-CoV) or development of SARS as a functional receptor. By cloning of the full-length cDNA of the ACE2 gene in the lung, where replication occurs on SARS-CoV, it was shown that there are different splicing sites. All exons including the new alternative exon, exon-intron boundaries, and the corresponding 5'-flanking region of the gene were investigated and 19 single nucleotide polymorphisms (SNPs) were found. Out of these, 13 SNPs including one non-synonymous substitution and three 3'-UTR polymorphisms were newly identified. A case control study involving 44 SARS cases, 16 anti-SARS-CoV antibody-positive contacts, 87 antibody-negative contacts, and 50 non-contacts in Vietnam, failed to obtain any evidence that the ACE2 gene polymorphisms are involved in the disease process in the population. Nevertheless, identification of new 5'-untranslated exon and new SNPs is considered helpful in investigating regulation of ACE2 gene expression in the future.

5' Flanking Region↗

PubMed2005

Polymorphisms of interferon-inducible genes OAS-1 and MxA associated with SARS in the Vietnamese population.

We hypothesized that host antiviral genes induced by type I interferons might affect the natural course of severe acute respiratory syndrome (SARS). We analyzed single nucleotide polymorphisms (SNPs) of 2',5'-oligoadenylate synthetase 1 (OAS-1), myxovirus resistance-A (MxA), and double-stranded RNA-dependent protein kinase in 44 Vietnamese SARS patients with 103 controls. The G-allele of non-synonymous A/G SNP in exon 3 of OAS-1 gene showed association with SARS (p=0.0090). The G-allele in exon 3 of OAS-1 and the one in exon 6 were in strong linkage disequilibrium and both of them were associated with SARS infection. The GG genotype and G-allele of G/T SNP at position -88 in the MxA gene promoter were found more frequently in hypoxemic group than in non-hypoxemic group of SARS (p=0.0195). Our findings suggest that polymorphisms of two IFN-inducible genes OAS-1 and MxA might affect susceptibility to the disease and progression of SARS at each level.

2',5'-Oligoadenylate Synthetase↗

PubMed2005

Survey of human immunodeficiency virus (HIV)-seropositive patients with mycobacterial infection in Japan.

OBJECTIVE: To assess DNA polymorphisms in mycobacterial isolates obtained from human immunodeficiency virus (HIV)-seropositive patients with tuberculosis in Japan from 1996 to 2003. METHODS: Restriction fragment length polymorphisms (RFLP) from Mycobacterium tuberculosis and Mycobacterium avium isolates obtained from individual seropositive patients with tuberculosis (n=78) were analysed with the use of IS6110 and (CGG)(5) or IS1245 and IS1311, respectively, as markers. As a control, the same procedures were applied to isolates from HIV-seronegative tuberculosis patients (n=87). RESULTS: Of 86 mycobacterial strains, M. tuberculosis, M. avium and Mycobacterium chelonae were identified in 48 (55.8%), 36 (41.9%) and 2 (2.3%) isolates, respectively. The obtained RFLP patterns of M. tuberculosis isolates from both the HIV-seropositive and -seronegative groups were variable, suggesting no obvious clustering among the isolates. Similar results were obtained in isolates of M. avium. CONCLUSIONS: This is the first report on the molecular epidemiology of Mycobacterium spp. isolated from HIV-seropositive patients in Japan. The results indicate that no particular clones of M. tuberculosis or M. avium prevail in HIV-seropositive patients in Japan. Further monitoring of mycobacterial infection associated with HIV infection in Japan should be continued.

Adolescent↗

PubMed2005

Rhodococcus equi can survive a phagolysosomal environment in macrophages by suppressing acidification of the phagolysosome.

Rhodococcus equi is one of the most important causes of pneumonia in foals and has emerged as a significant opportunistic pathogen of immunosuppressed hosts such as human immunodeficiency virus-infected patients. Virulent R. equi harbouring an 85 kb plasmid, but not the avirulent form lacking the plasmid, has the ability to survive in macrophages. However, the survival mechanism is not known. In the present study, morphological interactions were observed between virulent or plasmid-cured avirulent R. equi and phagolysosomes in murine macrophage-like J774.1 cells by immunocytological methods. The J774.1 cells phagocytosed virulent and avirulent bacteria to a similar extent, and both bacteria replicated in single membrane vacuoles at similar rates up to 6 h after infection. Thereafter, the virulent bacteria continued to grow, whereas the avirulent bacteria stopped growing. When the infected cells were stained with phagosomal and lysosomal markers and observed with a confocal fluorescence microscope, the majority of phagosomes containing these bacteria were fused with lysosomes. Neither R. equi organism has the ability to hinder phagosome-lysosome fusion. The acidity in phagolysosomes containing R. equi was examined by staining with LysoTracker Red DND-99, an acidotropic probe. The phagolysosomes containing virulent organisms were not acidic as compared with avirulent organisms. Over 90% of the phagolysosomes containing avirulent R. equi were stained with LysoTracker 6 h after infection, whereas less than 50% of those containing virulent R. equi were stained. Furthermore, when the supernatant obtained from a virulent R. equi culture was added to the cell cultures, the acidity of acidic compartments in macrophages was reduced. The authors conclude that some substance(s) produced by virulent R. equi suppress acidification in phagolysosomes, and help R. equi survival and replication in the bactericidal environment.

Amines↗

PubMed2005

Multidrug-resistant Pseudomonas aeruginosa strain that caused an outbreak in a neurosurgery ward and its aac(6')-Iae gene cassette encoding a novel aminoglycoside acetyltransferase.

We characterized multidrug-resistant Pseudomonas aeruginosa strains isolated from patients involved in an outbreak of catheter-associated urinary tract infections that occurred in a neurosurgery ward of a hospital in Sendai, Japan. Pulsed-field gel electrophoresis of SpeI-, XbaI-, or HpaI-digested genomic DNAs from the isolates revealed that clonal expansion of a P. aeruginosa strain designated IMCJ2.S1 had occurred in the ward. This strain possessed broad-spectrum resistance to aminoglycosides, beta-lactams, fluoroquinolones, tetracyclines, sulfonamides, and chlorhexidine. Strain IMCJ2.S1 showed a level of resistance to some kinds of disinfectants similar to that of a control strain of P. aeruginosa, ATCC 27853. IMCJ2.S1 contained a novel class 1 integron, In113, in the chromosome but not on a plasmid. In113 contains an array of three gene cassettes of bla(IMP-1), a novel aminoglycoside resistance gene, and the aadA1 gene. The aminoglycoside resistance gene, designated aac(6')-Iae, encoded a 183-amino-acid protein that shared 57.1% identity with AAC(6')-Iq. Recombinant AAC(6')-Iae protein showed aminoglycoside 6'-N-acetyltransferase activity by thin-layer chromatography. Escherichia coli expressing exogenous aac(6')-Iae showed resistance to amikacin, dibekacin, isepamicin, kanamycin, netilmicin, sisomicin, and tobramycin but not to arbekacin, gentamicins, or streptomycin. Alterations of gyrA and parC at the amino acid sequence level were detected in IMCJ2.S1, suggesting that such mutations confer the resistance to fluoroquinolones observed for this strain. These results indicate that P. aeruginosa IMCJ2.S1 has developed multidrug resistance by acquiring resistance determinants, including a novel member of the aac(6')-I family and mutations in drug resistance genes.

Acetyltransferases↗

PubMed2005

Cloning and characterization of a novel trimethoprim-resistant dihydrofolate reductase from a nosocomial isolate of Staphylococcus aureus CM.S2 (IMCJ1454).

A novel gene, dfrG, encoding a trimethoprim (TMP)-resistant dihydrofolate reductase (DHFR, designated S3DHFR) was cloned from a clinical isolate of methicillin-resistant Staphylococcus aureus. Escherichia coli expressing dfrG was highly resistant to TMP. Recombinant S3DHFR exhibited DHFR activity that was not inhibited by TMP.

Amino Acid Sequence↗

PubMed2005

Sputum cathelicidin, urokinase plasminogen activation system components, and cytokines discriminate cystic fibrosis, COPD, and asthma inflammation.

BACKGROUND: Interest in airways inflammatory disease has increasingly focused on innate immunity. We investigated several components of innate immunity in induced sputum of patients with cystic fibrosis (CF), COPD, and asthma, and healthy control subjects. METHODS: Twenty eight patients with mild CF lung disease (age > or = 12 years; FEV1, 74 +/- 3% predicted [mean +/- SE]), 74 adults with COPD (FEV1, 55 +/- 2% of predicted), 34 adults with persistent asthma (FEV1, 66 +/- 2% of predicted), and 44 adult control subjects (FEV1, 85 +/- 1% of predicted) were studied while in stable clinical condition. Levels of sputum interleukin (IL)-8, IL-10, interferon (IFN)-gamma, tumor necrosis factor (TNF)-alpha, human cationic antimicrobial protein 18 (CAP18), urokinase-type plasminogen activator (uPA), uPA receptor (uPAR), and plasminogen activator inhibitor (PAI)-1 were determined. Cell sources were investigated by flow cytometry and immunohistochemistry. Spirometry was performed prior to sputum induction. RESULTS: CF patient sputum showed greatest increase in IL-8 compared to that of patients with COPD and asthma (which were also greater than control subjects), and elevated levels of TNF-alpha and IL-10 compared to other groups. There were no differences in IFN-gamma. CAP18 levels were elevated in CF and COPD patients compared to control subjects, while asthma patients had reduced CAP18 levels. uPA levels were similar but uPAR was elevated in CF and COPD patients more so than in asthma patients, while PAI-1 levels were elevated in all three disease groups. CAP18 localized to neutrophil secondary granules; neutrophils were also sources of IL-8 and PAI-1. CAP18 and PAI-1 negatively correlated with pulmonary function. CONCLUSION: Induced-sputum innate immune factor levels discriminate inflammatory changes in CF, COPD, and asthma, suggesting potential roles in pathophysiology and as well as providing disease-specific biomarker patterns.

Adolescent↗