Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0348321 (Haemophilus)
 15,372 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A method for the isolation of Gardnerella vaginalis (Haemophilus vaginalis) is presented. Bacteria isolated from 48-hour cultures grown on human blood agar were identified by means of beta-hemolysis, colony morphology, sensitivity to antimicrobial agents, oxydase and catalase reactions. Thirty-eight clinical isolates and one test strain were examined for fatty acid composition. Hexadecanoic (16:0), octadecenoic (18:1) and octadecanoic (18:0) were the major fatty acids. Also present, but in minor quantities, were myristic (14:0), hexadecenoic (16:1) and octadecadienoic (18:2) acids. Only insignificant differences between isolates could be detected. No hydroxy fatty acids commonly found in gram-negative bacteria were encountered. Gas chromatographic analysis of G. vaginalis revealed a characteristic and relatively simple pattern. The results support the use of the isolation method, which provides conditions highly selective for G. vaginalis.
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PMID:Method for isolation of gardnerella vaginalis (Haemophilus vaginalis). Characterization of isolates by gas chromatography. 697 60

A total of 136 strains of Actinobacillus actinomycetemcomitans were studied for 135 features. All isolates were small nonmotile capnophilic gram-negative rods which grew with no requirement of X or V growth factors. They all decomposed hydrogen peroxide, were oxidase-negative and benzidine-positive, reduced nitrate, produced strong alkaline and acid phosphatases, and fermented fructose, glucose and mannose. Variable fermentation results were obtained with dextrin, maltose, mannitol and xylose. Some isolates produced small amounts of gas. Representative strains of Haemophilus aphrophilus were morphologically and biochemically quite similar to A. actinomycetemcomitans. Characters which should prove to be useful to identify and distinguish these two species include catalase reaction. fermentation of lactose, starch, sucrose and trehalose, and resistance to sodium fluoride. This information allows a rapid diagnosis by species and may be helpful in studies of infections involving these organisms.
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PMID:Salient Biochemical Characters of Actinobacillus actinomycetemcomitans. 706 13

A selective medium, TSBV (tryptic soy-serum-bacitracin-vancomycin) agar, was developed for the isolation of Actinobacillus actinomycetemcomitans, TSBV agar contained (per liter) 40 g of tryptic soy agar, 1 g of yeast extract, 100 ml of horse serum. 75 mg of bacitracin, and 5 mg of vancomycin. The TSBV medium suppressed most oral species and permitted significantly higher recovery of A. actinomycetemcomitans than nonselective blood agar medium. The distinct colonial morphology and positive catalase reaction of A. actinomycetemcomitans easily distinguished this bacterium from Haemophilus aphrophilus, Capnocytophaga species, and a few other contaminating organisms. With the TSBV medium, even modestly equipped laboratories will be able to isolate and identify A. actinomycetemcomitans from clinical specimens.
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PMID:Selective medium for isolation of Actinobacillus actinomycetemcomitans. 706 37

Many clinical laboratories have difficulty in identifying a group of organisms which are catalase negative, oxidase positive, Gram negative rods. We describe a case of purulent sacroiliitis due to Haemophilus paraphrophilus where the organism was initially misidentified as Eikenella corrodens leading to inappropriate antimicrobial chemotherapy. We review the strains of H. paraphrophilus and E. corrodens that were identified by the National Collection of Type Cultures over the last ten years. Only 21 of 100 strains identified as E. corrodens were submitted as E. corrodens. Seven strains submitted as possible E. corrodens were identified as H. paraphrophilus. Several different species of Gram negative rods may produce pitting on agar and this seems to be poorly recognised. However, further tests are available to facilitate correct identification of these strains.
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PMID:Haemophilus paraphrophilus infection: a pitfall in laboratory diagnosis. 775 71

A single catalase enzyme was produced by the anaerobic bacterium Bacteroides fragilis when cultures at late log phase were shifted to aerobic conditions. In anaerobic conditions, catalase activity was detected in stationary-phase cultures, indicating that not only oxygen exposure but also starvation may affect the production of this antioxidant enzyme. The purified enzyme showed a peroxidatic activity when pyrogallol was used as an electron donor. It is a hemoprotein containing one heme molecule per holomer and has an estimated molecular weight of 124,000 to 130,000. The catalase gene was cloned by screening a B. fragilis library for complementation of catalase activity in an Escherichia coli catalase mutant (katE katG) strain. The cloned gene, designated katB, encoded a catalase enzyme with electrophoretic mobility identical to that of the purified protein from the B. fragilis parental strain. The nucleotide sequence of katB revealed a 1,461-bp open reading frame for a protein with 486 amino acids and a predicted molecular weight of 55,905. This result was very close to the 60,000 Da determined by denaturing sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the purified catalase and indicates that the native enzyme is composed of two identical subunits. The N-terminal amino acid sequence of the purified catalase obtained by Edman degradation confirmed that it is a product of katB. The amino acid sequence of KatB showed high similarity to Haemophilus influenzae HktE (71.6% identity, 66% nucleotide identity), as well as to gram-positive bacterial and mammalian catalases. No similarities to bacterial catalase-peroxidase-type enzymes were found. The active-site residues, proximal and distal hemebinding ligands, and NADPH-binding residues of the bovine liver catalase-type enzyme were highly conserved in B. fragilis KatB.
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PMID:Biochemical and genetic analyses of a catalase from the anaerobic bacterium Bacteroides fragilis. 776 8

In addition to detoxifying peroxides generated by aerobic metabolism, the catalases of pathogenic bacteria have also been hypothesized to serve as virulence factors by enabling microorganisms to resist the oxidative bursts of host inflammatory cells. Using transposon mutagenesis of the hktE gene, encoding the Haemophilus influenzae structural gene for catalase, we constructed defined catalase mutants of H. influenzae strains Rd- and Eagan b+. These mutants show no detectable catalase production during exponential or stationary phases or following induction with hydrogen peroxide or ascorbic acid, indicating that hktE is the only functional hydroperoxidase gene present in these two strains of H. influenzae. Exponential-phase cultures of hktE mutants are 8- to 25-fold more sensitive to hydrogen peroxide than the wild type. Using the infant rat model, hktE mutants of strain Eagan b+ were 2.3-fold less virulent than the wild type following intraperitoneal inoculation (P = 0.07). When administered intranasally, the Eagan b+ hktE mutant produced wild-type levels of bacteremia and nasal colonization. The results of this study show that while the H. influenzae hktE gene is important for survival in the presence of peroxides, deletion of the gene produces only a modest reduction in ability to cause lethal sepsis following parenteral challenge and no change in ability to colonize following intranasal inoculation in the infant rat model of infection.
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PMID:Characterization and virulence analysis of catalase mutants of Haemophilus influenzae. 792 66

Bacterial catalases are induced by exposure to peroxide (e.g., Escherichia coli katG) or entry into stationary phase (e.g., E. coli katE). To study regulatory systems in Haemophilus influenzae, we complemented an E. coli rpoS mutant, which is unable to induce katE in stationary phase, with a plasmid library of H. influenzae Rd- chromosomal DNA. Nineteen complementing clones with a catalase-positive phenotype were obtained and characterized after screening about 10(5) transformants. All carried the same structural gene for an H. influenzae catalase. The DNA sequence of this gene, called hktE, encodes a 508-amino-acid polypeptide with strong homology to eukaryotic catalases and E. coli katE. However, hktE is regulated like E. coli katG, with catalase activity increasing 10-fold and hktE mRNA levels increasing 4-fold upon exposure to ascorbic acid, which serves to generate hydrogen peroxide. Mutations in the known global regulatory genes of H. influenzae--crp, cya, and sxy--do not affect the inducibility of hktE. The hktE gene maps to a 225-kb segment of the H. influenzae chromosome in a region encoding resistance to spectinomycin.
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PMID:A peroxide/ascorbate-inducible catalase from Haemophilus influenzae is homologous to the Escherichia coli katE gene product. 818 93

The structural gene for the catalase of Neisseria gonorrhoeae was cloned into a Kat- strain of that organism by using a recombinant vector derived from one of the beta-lactamase-specifying plasmids found in that organism. The kat gene was then successfully subcloned into both pUC8 and pGB2, transformed into Escherichia coli, and shown to complement the E. coli katE mutants UM2 and UMRl. The gene was subsequently mutagenized and returned to the gonococcus to generate a Kat- strain that was phenotypically identical to the strain originally used to clone the gene. The sequence of the gene and the derived amino acid sequence showed that the gonococcal kat gene closely resembles the hktE gene of Haemophilus influenzae. The sequence of the promoter region of the gonococcal kat gene is unusual and may explain the extremely high, loosely regulated expression of the gene.
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PMID:Cloning and characterization of the catalase gene of Neisseria gonorrhoeae: use of the gonococcus as a host organism for recombinant DNA. 869 88

A pBR322-based library of chromosomal DNA from the nontypeable Haemophilus influenzae TN106 was screened for the expression of transferrin-binding activity in Escherichia coli. A recombinant clone expressing transferrin-binding activity contained a 3.7-kb fragment of nontypeable H. influenzae DNA. Nucleotide sequence analysis of this insert revealed the presence of two complete open reading frames encoding proteins of approximately 26 and 34 kDa. Mini-Tn10kan transposon mutagenesis at different sites within the open reading frame encoding the 34-kDa protein resulted in the abolition of transferrin-binding activity in the recombinant E. coli clone. The deduced amino acid sequence of the 34-kDa protein had 70% identity with the OxyR protein of E. coli; this latter macromolecule is a member of the LysR family of transcriptional activators. When a mutated H. influenzae oxyR gene was introduced into the chromosome of the wild-type H. influenzae strain by allelic exchange, the resulting oxyR mutant still exhibited wild-type levels of transferrin-binding activity but was unable to grow on media containing the heme precursor protoporphyrin IX (PPIX) in place of heme. This mutant also exhibited reduced growth around disks impregnated with heme sources. Supplementation of the PPIX-based growth media with catalase or sodium pyruvate resulted in normal growth of the H. influenzae oxyR mutant. Provision of the wild-type H. influenzae oxyR gene in trans also permitted the growth of this mutant on a PPIX-based medium. Exogenously supplied catalase restored the growth of this mutant with heme sources to nearly wild-type levels. These results indicate that expression of a wild-type OxyR protein by H. influenzae is essential to allow this organism to protect itself against oxidative stresses in vitro.
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PMID:Lack of expression of the global regulator OxyR in Haemophilus influenzae has a profound effect on growth phenotype. 889 Feb 16

The N-terminal sequence of a protein, originally described as an adhesin of Helicobacter pylori, was used in an oligonucleotide-based screening procedure of an H. pylori plasmid library in Escherichia coli. Five independent plasmid clones were isolated, all mapping to the same chromosomal region and encoding the H. pylori catalase. The gene, designated katA, comprises 1,518 nucleotides and encodes a putative protein of 505 amino acids with a predicted Mr of 58,599. A second open reading frame, orf2, encoding a putative 32,715-Da protein of unknown function, follows katA. The transcriptional start site of katA mRNA was determined, but no typical consensus promoter sequence was present. A potential binding site for the Fur protein is located upstream of katA. When introduced into the catalase-deficient E. coli double-mutant UM255, the cloned gene readily complemented E. coli for catalase activity. H. pylori KatA is highly homologous to catalases in both prokaryotes and eukaryotes, with the highest homology being shown to Bordetella pertussis (64.9%), Bacteroides fragilis (59.8%), and Haemophilus influenzae (57.9%) catalases. Transposon insertion mutants were generated in three independent H. pylori strains by TnMax5-mediated transposon shuttle mutagenesis. In contrast to the wild-type strains, no significant catalase-specific enzymatic activity could be detected in the mutant strains, consistent with the fact that no additional katA-homologous gene copies were found in the H. pylori chromosome. No significant difference between wild-type and mutant strains for binding to epithelial cells was apparent, suggesting that KatA is not involved in H. pylori adhesion. The cloning and genetic characterization of katA are essential steps for further investigation of the role of catalase in the defense of H. pylori against oxygen-dependent killing mechanisms by polymorphonuclear granulocytes, a process not well understood for this chronically persisting pathogen.
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PMID:Cloning and genetic characterization of Helicobacter pylori catalase and construction of a catalase-deficient mutant strain. 895 20


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