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)

There is poor correlation between the MICs and zone sizes obtained for erythromycin against Haemophilus influenzae. The effect of two media, Mueller-Hinton medium supplemented with 3% lysed horse blood and 10 micrograms of NAD per ml (MHA + LYHB) and Mueller-Hinton agar supplemented with 1% bovine hemoglobin and 1% IsoVitaleX (MHA + HGB), on the MICs and zone sizes of erythromycin against H. influenzae was determined. The effect of three different methods for inoculum preparation on the susceptibility of H. influenzae was also determined. The MICs were independent of the method of inoculum preparation, but the zone sizes were smaller if the inoculum was carefully adjusted to contain approximately 10(8) CFU/ml. MICs were higher and zone sizes were smaller when MHA + HGB was used instead of MHA + LYHB. Good correlation was found when MHA + LYHB was used for determining the MIC and MHA + HGB was used for determining susceptibility by the disk method. When the inoculum was adjusted to match a McFarland 0.5 standard, the viable counts had to be approximately 10(8) CFU/ml for good correlation between MICs and zone sizes. A-56268, a new macrolide antibiotic, was tested against H. influenzae, and its MICs and tentative breakpoints against this organism were determined. The MICs obtained by various methods were correlated with in vivo efficacy by using a mouse septicemia model. MICs obtained on MHA + HGB or MHA + LYHB incubated without a 5% CO2 atmosphere showed the best correlation with in vivo efficacy.
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PMID:Susceptibility testing of macrolide antibiotics against Haemophilus influenzae and correlation of in vitro results with in vivo efficacy in a mouse septicemia model. 295 54

Four separate laboratories performed antimicrobial susceptibility tests with 40 Haemophilus influenzae isolates, each tested in triplicate. Erythromycin and a new macrolide, clarithromycin (A-56268; TE-031), were tested by the disk diffusion method, by the agar dilution procedure in two different media, and by broth microdilution tests in four different media. Erythromycin MICs for 90% of the strains were 16 micrograms/ml in Mueller-Hinton broth with 3% lysed horse blood and NAD, 4.0 micrograms/ml in hemophilus test medium, and 2.0 micrograms/ml in supplemented Schaedler broth or in the fastidious broth medium from Beckman Instruments, Inc. Clarithromycin MICs were generally 1 doubling dilution greater than erythromycin MICs in each of the media. Erythromycin disk tests corresponded best with MICs determined in the fastidious broth medium. In that same medium, clarithromycin MICs were about 1 doubling dilution greater than what would be expected from the results of disk tests. Because there were fewer growth failures, hemophilus test medium is recommended for microdilution tests with H. influenzae. Incubation of all tests for a full 24 h without an increased CO2 atmosphere was needed to achieve maximal precision of the tests. Interlaboratory and intralaboratory reproducibility of all tests was satisfactory.
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PMID:Variability of clarithromycin and erythromycin susceptibility tests with Haemophilus influenzae in four different broth media and correlation with the standard disk diffusion test. 297 73

A nucleotide pyrophosphatase isolated from Haemophilus influenzae was purified to electrophoretic homogeneity and characterized with respect to molecular weight, substrate specificity, pH profile, thermal stability, functional group involvement, and effectiveness of selective inhibition. The enzyme catalyzes the hydrolysis of NAD to NMN and AMP and appears located appropriately to facilitate the internalization of NAD needed to satisfy the V-factor growth requirement of the organism. In the processing of NAD and structurally related substrates, the enzyme exhibited negative cooperativity. Structural alterations in the purine moiety of these dinucleotide substrates had pronounced effects on the negative cooperativity of the enzyme. AMP, ADP, and several related nucleotides were observed to be effective substrate-competitive inhibitors of the enzyme. Several of the dinucleotides serving as substrates for the nucleotide pyrophosphatase were evaluated with respect to substituting for NAD in supporting growth of the organism. AMP and ADP inhibited growth of the organism when NAD served as V-factor, and this inhibition correlated well with the inhibitory effects of these nucleotides on the purified nucleotide pyrophosphatase.
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PMID:Characterization of Haemophilus influenzae nucleotide pyrophosphatase. An enzyme of critical importance for growth of the organism. 300 42

Haemophilus influenzae malate dehydrogenase [S)-malate: NAD+ oxidoreductase EC 1.1.1.37) was purified 109-fold with a 26% recovery through a four-step procedure involving salt fractionation, hydrophobic and dye affinity chromatography. The purified enzyme was demonstrated to be a dimer of Mr 61,000. Initial velocity studies of all four substrates in the forward and reverse reactions indicated a sequential mechanism for the enzyme. Product and dead-end inhibition studies were consistent with an ordered bi-bi mechanism in which NAD is the first substrate bound to the enzyme and NADH, the second product released. Several analogs of NAD structurally altered in either the pyridine or purine moiety were observed to function as coenzymes in the reaction catalyzed by the purified malate dehydrogenase. Alterations in the purine portion of the dinucleotides had a more pronounced effect on the kinetic parameters observed in malate oxidation. The enzyme was inactivated by incubation with diethylpyrocarbonate, whereas no inactivation was observed with sulfhydryl reagents.
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PMID:Kinetic studies of Haemophilus influenzae malate dehydrogenase. 326 Jan 11

Outer membrane protein (OMP)-enriched extracts and whole-cell protein preparations of Haemophilus (Actinobacillus) pleuropneumoniae and related organisms were examined by polyacrylamide gel electrophoresis and immunoblotting. Both the OMP-enriched and whole-cell protein profiles of Actinobacillus suis, A. pleuropneumoniae (NAD-independent biovar), A. lignieresii, and Pasteurella haemolytica were very similar to those of H. pleuropneumoniae serotypes 1 to 8. Antisera prepared against H. pleuropneumoniae typically recognized three major OMP antigens with approximate molecular weights of 17,000 (17K), 32K, and 42K in immunoblots of H. pleuropneumoniae serotypes 1 to 8, Actinobacillus spp., and P. haemolytica. Antisera prepared against Actinobacillus spp. and Haemophilus sp. "minor group" also recognized these 17K, 32K, and 42K antigens. Using absorbed sera, we demonstrated that the 17K antigen had an epitope (or epitopes) common to all the gram-negative organisms examined, including Escherichia coli. The 32K and 42K antigens had epitopes common to members of the family Pasteurellaceae but, in the case of the 32K antigen, also contained unique epitopes. These results provide a basis for understanding the lack of specificity of serodiagnostic tests for H. pleuropneumoniae infection and provide another line of evidence for the association of H. pleuropneumoniae with the genus Actinobacillus.
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PMID:Analysis of major antigens of Haemophilus (Actinobacillus) pleuropneumoniae and related organisms. 329 61

Both Neisseria meningitidis and Haemophilus influenzae are important isolates recovered in blood cultures from septicemic children. Sodium polyanetholsulfonate is present in most blood culture media and can inhibit the growth of certain bacteria, including N. meningitidis. The addition of gelatin to blood culture media neutralizes this inhibition. The growth of H. influenzae is enhanced by specific growth factors such as hemin and NAD. The addition of gelatin and V-factor-analog (a proprietary supplement for enhancing the growth of H. influenzae) might have a positive effect on the yield and on the speed of detection of septicemia in children. To evaluate this possibility, we did 4,565 paired comparisons of blood cultured in BACTEC 6B (aerobic) medium with and without the addition of both 1.2% gelatin and V-factor-analog. More aerobic and facultative bacteria grew in the 6B than in the 6B-gelatin-V-factor-analog medium (P less than 0.01). Only seven isolates of Neisseria spp. were recovered during this study period, with the 6B medium performing as well as the supplemented medium. When microorganisms grew in both bottles, they did so at the same time except for H. influenzae and Candida albicans. H. influenzae was recovered earlier from the 6B-gelatin-V-factor-analog bottle (P less than 0.01), with a mean time to detection of 8.5 h compared with 15.9 h for the 6B bottle. C. albicans was recovered earlier from the 6B bottle (P less than 0.02), with a mean time to detection of 34.9 h compared with 71.6 h for the 6B-gelatin-V-factor-analog bottle. We conclude that the 6B medium in its present formulation is superior to bB supplemented with gelatin and V-factor-analog.
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PMID:Controlled evaluation of blood culture medium containing gelatin and V-factor-analog for detection of septicemia in children. 336 69

A broth system was developed for rapid identification of the requirement for X factor (hemin), or V factor (NAD), or both for growth of Haemophilus species. This system was compared to growth around paper discs/strips impregnated with factors X and/or V. The broth system consisted of three tubes, each containing brain-heart infusion broth supplemented with V factor, X factor, or both. Each tube was inoculated with a saline suspension of an Haemophilus isolate, and the broths were shaken for aeration at 37 degrees C. Under these conditions turbidity or clumping was usually evident after 4-5 hr only in the broth(s) containing the required supplement(s). A few strains requiring only V factor required overnight incubation. One hundred fifty-six Haemophilus isolates were tested for growth around supplemented discs/strips or in supplemented broths: 129 were H. influenzae/aegypticus, 25 were of various species that required only V factor, and 2 were H. aphrophilus. Ten of 89 H. influenzae isolates from the respiratory tract were misidentified by satellitism. All isolates were correctly identified by growth in supplemented broths. The cost of the broth assay was about 60 cents/test, whereas the satellite assay cost about 120 cents/test. Serotyping and antibiotic sensitivity testing could be performed directly from the broth culture. Determination of X and/or V requirement by Haemophilus species with supplemented broths was sensitive, rapid, and inexpensive.
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PMID:Rapid determination of X/V growth requirements of Haemophilus species in broth. 349 13

The need for complex growth media has complicated routine susceptibility testing of Haemophilus influenzae because of antagonism of certain antimicrobial agents by the medium or because of difficulties in interpretation of growth endpoints. Haemophilus test medium (HTM) is a simple, transparent medium for broth- or agar-based tests with H. influenzae. HTM incorporates Mueller-Hinton medium with additions of 15 micrograms of hematin per ml, 15 micrograms of NAD per ml, and 5 mg of yeast extract per ml as growth-promoting additives. Agar or broth microdilution MICs of 10 antimicrobial agents for a collection of 179 H. influenzae isolates determined by using HTM compared favorably with MICs determined by the conventional agar or broth dilution methods recommended by the National Committee for Clinical Laboratory Standards. Disk diffusion tests performed with HTM allowed accurate categorization of susceptible and resistant strains and were easier to interpret than tests performed with Mueller-Hinton chocolate agar. A particular advantage of HTM was the reliability of broth- or agar-based test results with trimethoprim-sulfamethoxazole. The results of the study suggest modification of current National Committee for Clinical Laboratory Standards MIC-interpretive criteria for H. influenzae with amoxicillin-clavulanate, chloramphenicol, and trimethoprim-sulfamethoxazole. Error rate-bounded analysis of MICs and disk diffusion zone sizes also suggest modified zone-interpretive criteria for ampicillin, amoxicillin-clavulanate, chloramphenicol, and tetracycline with HTM or conventional media. Interpretive zone sizes are newly proposed for cefaclor and rifampin disk diffusion tests.
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PMID:Improved medium for antimicrobial susceptibility testing of Haemophilus influenzae. 350 Sep 65

A simple micromethod in a liquid medium using the API-ATB system was developed for testing the susceptibility of Haemophilus to antibiotics. To evaluate this method, 50 strains, including 12 beta-lactamase producers, were studied. Results were compared to those obtained using MIC determination in a liquid medium (reference) and an agar diffusion method (routine). For all three techniques, a Mueller-Hinton medium enriched in hemoglobin and NAD was used, and cultures were incubated at 37 degrees C for 24 hours in normal atmosphere. Influence of the inoculum on results was evaluated using the API-ATB method for all antibiotics and MIC determination for ampicillin; the optimal inoculum was found to be 8.10(5) CFU/ml. Beta-lactamase was looked for using the chromogen cephalosporin test associated with the API-ATB system. Values of MICs for the various antibiotics were consistent with previous reports. Paired comparison of techniques showed a 5.3% disagreement rate between API-ATB and MIC, with only 0.5% major discrepancies; in contrast, the disagreement rate exceeded 10% when disk diffusion was compared with the two other techniques. We conclude to the reliability and reproducibility of the API-ATB method which seems capable of improving current routine evaluations of the susceptibility of Haemophilus to antibiotics.
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PMID:[Evaluation of the sensitivity of Haemophilus to antibiotics by the modified API-ATB system]. 391 Nov 54

The uptake of homologous DNA by Haemophilus influenzae was studied as a function of the proton motive force in completely competent cultures in the pH range of 6 to 8. The composition and magnitude of the proton motive force were varied by using the ionophores valinomycin and nigericin (in the presence of various potassium ion concentrations) and by using protonophores. No interaction of the ionophores with the DNA transformation system itself was observed. Either component of the proton motive force, the electrical potential or the pH gradient, can drive the uptake of DNA, and the extent of the uptake of DNA is ultimately determined by the total proton motive force. The transformation frequency increases with the proton motive force, which reaches a maximum value at around -130 mV. These results are consistent with an electrogenic proton-DNA symport mechanism, but direct evidence for such a system is not available. The proton motive force was followed during competence development of H. influenzae at pH 8. In the initial phase (up to 50 min), the proton motive force remained constant at about -90 mV, whereas the transformation frequency rose steeply. In the second phase, the proton motive force increased. The transformation frequency in this phase increased with the proton motive force, as in completely competent cultures. These observations and the observed inhibition by NAD of both the proton motive force and the transformation frequency indicate that structural components of the competent state are formed in the initial phase of competence development, whereas the second phase is characterized by an increase of the proton motive force.
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PMID:Role of the electrochemical proton gradient in genetic transformation of Haemophilus influenzae. 632 40


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