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)

Quinupristin/dalfopristin is an injectable streptogramin antibiotic that is constituted in a 30:70 (w/w) ratio of the two components. Quinupristin and dalfopristin are thought to act synergically by binding to two separate sites on the bacterial 50S ribosomal subunit. The in-vitro activities of the two components separately and together in different ratios were determined for a collection of 100 Haemophilus influenzae strains representing various antimicrobial resistance phenotypes. The NCCLS microdilution susceptibility testing procedure incorporating Haemophilus test medium (HTM) broth was used to determine MICs of quinupristin, dalfopristin and seven other antimicrobial agents. The MIC50 and MIC90 values were 4 and 8, 4 and 16, and 64 and 128 mg/L for quinupristin/dalfopristin (30:70), dalfopristin and quinupristin, respectively. MICs of quinupristin and dalfopristin were also determined in Mueller-Hinton lysed horse blood broth and by HTM agar dilution testing. Compared with HTM broth-derived results, the MICs of quinupristin/dalfopristin and its components were the same or one dilution higher in lysed horse blood and HTM agar incubated in air, and were equivalent or one dilution lower in HTM agar incubated in a CO2 atmosphere. The MICs of quinupristin and dalfopristin separately or together were directly proportional to erythromycin MICs, but were otherwise unaffected by any of the resistance mechanisms represented in these strains. MICs of quinupristin and dalfopristin combined in ratios of 10:90, 70:30 and 90:10 did not differ significantly from those of the 30:70 ratio. Thus, unlike the synergic activity noted against Gram-positive bacteria, the activity of quinupristin/dalfopristin against H. influenzae appears to be due almost entirely to the dalfopristin component of the combination.
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PMID:Activity of quinupristin/dalfopristin and its components against Haemophilus influenzae. 951 Oct 67

For testing bacterial susceptibility to the streptogramin quinupristin/dalfopristin, it seems reasonable that the test reagent should contain a similar ratio of the two compounds as in the therapeutic material, i.e. 30% quinupristin and 70% dalfopristin. The precise ratio of quinupristin to dalfopristin is not critical as long as threshold concentrations of both drugs are present. In-vitro tests were not altered by minor changes in pH, incubation in CO2 or by addition of lysed horse blood to the medium. Filter paper discs containing 15 micrograms of the quinupristin/dalfopristin reagent are preferred for agar diffusion susceptibility testing in order to optimize disc tests with enterococci. Provisional interpretive criteria for pathogens not requiring blood or increased CO2 are: susceptible, inhibition zone diameters of > or = 19 mm or MIC < or = 1.0 mg/L; intermediate, 16-18 mm or MIC 2.0 mg/L; resistant, < or = 15 mm or MIC > or = 4.0 mg/L. Those criteria will need to be reassessed as clinical experiences become available. Of particular concern is the role of quinupristin/dalfopristin in the treatment of infections due to Haemophilus influenzae or Enterococcus faecalis: the clinically relevant interpretive category for each of those two species is yet to be determined.
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PMID:Provisional interpretive criteria for quinupristin/dalfopristin susceptibility tests. 951 Oct 70

Susceptibility testing of Eikenella corrodens is usually performed by a Mueller-Hinton sheep blood agar dilution (AD) method. However, this method is impractical for testing only a few strains. We compared AD with the broth microdilution method using Haemophilus test medium (HTM) in order to determine the susceptibility of 36 clinical isolates of E. corrodens to eight antimicrobial agents. MICs obtained by the HTM method yielded 95.5 and 84% agreement (within 2 and 1 log2 dilutions, respectively) with those obtained by AD. The HTM method with incubation in CO2 for 48 h was highly reproducible and constitutes an easy alternative for antimicrobial susceptibility testing of E. corrodens.
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PMID:Comparison of broth microdilution method using Haemophilus test medium and agar dilution method for susceptibility testing of Eikenella corrodens. 966 33

The failure to eradicate group A beta-hemolytic streptococci from the pharynx is partly due to a low compliance, but above all, an alteration of the oropharyngeal microbiological flora: reduction of alpha-haemolytic streptococci which inhibit group A beta-hemolytic streptococci and increase of microorganisms such as Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis. These latter act indirectly destroying the beta-lactamic ring of penicillins. However, this obstacle is overcome by the use of antibiotics which do not contain beta-lactamic rings such as macrolides or associating amoxicillin with clavulanic acid or with new cephalosporins which are more resistant to beta lactamases. To restrict the diffusion of resistance to antibiotics, it is essential to limit their use diagnosing streptococcal tonsillopharyngitis more precisely, thanks to an improved use of micro-biological diagnostic tests and by a more extended use of tonsillectomy in recurrent tonsillitis (more than 6-7 in 1-2 years). Adenoiditis is closely related to the post nasal drip syndrome, to recurrent otitis media and to otitis media with effusion. All these situations could, therefore, represent an indication, although not well defined, for adenoidectomy. Nasopharyngeal obstruction due to adeno-tonsillar hypertrophy becomes critical during sleep when the hypotony of the upper airway muscles becomes additional to the anatomical obstruction. At this point the inspiratory effort required and the consequent decrease of intra airway pressure increase the pharyngeal obstruction suctioning the pharyngeal walls toward the median line. The resulting clinical picture is defined as sleep-disordered breathing (SDB) due to adenotonsillar hypertrophy (idiopathic), to be distinguished from SDB due to cranio-facial abnormalities or neuromuscular diseases. SDB includes both the more serious sleep apnea syndrome and the less severe upper airway respiratory resistance syndrome. A combination of symptoms and clinical data detectable both while awake or asleep, make the diagnosis simple. During sleep, both apnea and paradoxical inspiratory movements are highly specific while snoring is highly sensitive. To evaluate nasopharyngeal obstruction radiography and optic fibre endoscopy are both equally reliable. The gold standard test for non idiopathic SDB is the polysomnography, whereas for SDB, due to adenotonsillar hypertrophy, one is limited today to the recording during sleep of O2 saturation or of end tidal CO2. These investigations are, however, generally used up to 2 years of age, when the decision to carry out an adenoidectomy and especially a tonsillectomy is more difficult because of the greater risks which surgery involves at this age. The pharmacological therapy has a purely palliative function and is based on antibiotics, local vasoconstrictors, steroids and theophylline which acts more as an antiflogistic than as a breath stimulant. O2 therapy and nasal continuous positive airway pressure (CPAP) give better results, but are more difficult to carry out, in particular on a long term basis. Adenoidectomy especially if associated with tonsillectomy, leads to the resolution of the symptoms, but not always to a normalization of functional alterations (hypoxia and hypercapnia). For this reason, it is necessary to act on other factors which cause oedema of the nasopharyngeal mucosa contributing to the obstruction. In this area, the prevention of viral infections can be achieved by vaccination against influenza and by preventing the child from attending crowded day care centers. With regard to allergic inflammation, skin prick tests could be a first step in view of allergens avoidance measures. With regard to indoor air pollution, passive smoke must be stopped and the child kept out of the kitchen.
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PMID:[The tonsils and adenoids as a site of infection and the cause of obstruction]. 986 45

The use of macrolides for treatment of respiratory complaints has been complicated by susceptibility test conditions that adversely effect the in vitro test results and perceived potencies of these compounds. Dirithromycin was studied as to its in vitro activity compared to other macrolides as well as the effects that environmental incubation variations and inoculum concentrations may have on susceptibility results. Dirithromycin was less active than other macrolides tested (azithromycin clarithromycin, erythromycin) against Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis with MIC90 values of 16, 32, and 1 microgram/ml, respectively; an activity that was most similar to roxithromycin. This reduced activity may be compensated by the superior pharmacokinetic properties that dirithromycin possesses compared to other members in its class. Method variation studies show that incubation in CO2 environments increase the MIC values for all macrolide compounds and dirithromycin was most effected by pH changes in three in vitro methods tested (Etest [AB BIODISK, Solna, Sweden] broth microdilution, and disk diffusion). Variations in inoculum concentration had minimal effect on dirithromycin potency. In addition the variability (lack of reproducibility) of the test results with dirithromycin were not significant. Dirithromycin is an alternative therapeutic choice among macrolide compounds for treatment of community-acquired respiratory infections caused by various streptococci, Legionella pneumophilia, Mycoplasma pneumoniae and M. catarrhalis, and also possesses a modest in vitro potency versus H. influenzae coupled with excellent pharmacokinetic properties. In vitro tests with dirithromycin will continue to be problematic for H. influenzae because of the adverse effects of recommended CO2 incubation for some standardized methods or commercial products (Etest).
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PMID:Comparative in vitro evaluation of dirithromycin tested against recent clinical isolates of Haemophilus influenzae, Moraxella catarrhalis, and Streptococcus pneumoniae, including effects of medium supplements and test conditions on MIC results. 1021 55

Three Haemophilus somnus isolates (2a, 3a, and 27b) and one H. somnus-like (13b) isolate from tonsils of commercially reared American bison were compared with 2 known H. somnus isolates from cattle, namely, 2336, shown to cause respiratory disease, and 129Pt, from the prepuce of an asymptomatic bull. All H. somnus isolates, but not the H. somnus-like isolate, required CO2 for growth. Biochemical utilization profiles were identical for bison and bovine H. somnus isolates with the exception of alpha-fucosidase production by isolate 3a. Isolate 27a varied from 2a, 2336 and 129Pt by hemolysis of bovine erythrocytes. Isolate 13b hemolyzed sheep but not bovine or bison erythrocytes and varied from other isolates in biochemical utilization tests. Outer membrane protein profiles of 2a, 3a and 27a were almost identical with those of bovine isolate 2336 and similar to that of 129Pt, but quite different from that of 13b. Western blots of bison isolates were similar to that of the virulent bovine 2336 isolate, including detection of high molecular mass antigens above 100 kDa and the 76 kDa antigens associated with bovine IgG2 Fc binding characteristic of virulent strains, as well as antigens of approximately 78, 60 and 40 kDa. Producers and veterinarians should be aware that H. somnus may be carried by bison and may have potential for causing diseases in bison similar to those described in cattle and sheep.
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PMID:Characterization of putative Haemophilus somnus isolates from tonsils of American bison (Bison bison). 1048 Apr 57

Susceptibility testing of Haemophilus influenzae to the macrolide compounds has often been problematic. This is as a result of the inability of many isolates of H. influenzae to grow without the addition of 5% CO2 to the incubation atmosphere and the subsequent detrimental effect that CO2 has on the activity of the macrolide group of compounds. This report describes refinements and recommendations for susceptibility testing of H. influenzae to the macrolide clarithromycin.
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PMID:Susceptibility testing of Haemophilus influenzae to clarithromycin. 1074 33

Linezolid has excellent antibacterial activity against a wide range of Gram-positive organisms. Early in vitro investigations suggested that the compound also had activity against some Gram-negative species, including those commonly associated with community-acquired respiratory tract infections (Haemophilus influenzae and Moraxella catarrhalis). Against 603 recent clinical isolates of H. influenzae from geographically diverse regions of the world, tested by the reference broth microdilution method (HTM), linezolid MIC values ranged from 2-64 microg/ml (MIC50 and MIC90 at 16 microg/ml and 32 microg/ml, respectively). A subset of 328 strains was also tested to compare broth microdilution and Etest (AB BIODISK, Solna, Sweden) methodologies. The Etest method produced slightly higher MIC results attributable to a growth-enhancing effect of the 5% CO2 incubation used in the test procedure and pH changes. Linezolid activity versus H. influenzae was limited as evidenced by reference test results (susceptible breakpoints at < or = 2 or < or = 4 microg/ml) and variable endpoints were obtained when alternative methods were used such as the Etest or standardized disk diffusion procedures. Clinical laboratories should limit the testing of linezolid against Gram-negative species (H. influenzae).
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PMID:In vitro activity of linezolid (U-100766) against Haemophilus influenzae measured by three different susceptibility testing methods. 1117 91

Ten Haemophilus somnus isolates were grown on blood agar plates under a 5% CO2 atmosphere for 48 h. Harvested whole cells were washed and evaluated for the presence of histamine by ELISA. All H. somnus isolates had cell-associated histamine concentrations of between 18.5 and 200 ng/ml. In a separate study, the ability of H. somnus to secrete histamine into BHI growth medium was evaluated using H. somnus strains 8025 and 156A as well as a recent 156A respiratory isolate. Each strain or isolate was grown under various concentrations of CO2 to approximate the CO2 concentration in the bronchi. The histamine content of washed whole cells and medium supernatant were determined at various stages of incubation. Highest histamine concentrations were detected in the recent respiratory isolate; whole cells (225 ng/ml) after 120 h incubation in 15% CO2 and supernatant (1721 ng/ml) after incubation for 41 h in 25% CO2. This study indicates that different H. somnus isolates can produce and secrete histamine which may be enhanced by CO2 concentrations which approximate those in the bronchial tree. Results of this study may partially explain some of the post-vaccination reactions occasionally observed with H. somnus bacterins. Additional studies are needed to determine the actual role of H. somnus-derived histamine in the pathogenesis of bovine respiratory disease and airway hyperresponsiveness.
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PMID:Histamine production by Haemophilus somnus. 1183 43

OBJECTIVE: To evaluate the effect of carbon dioxide on the susceptibility testing, using broth microdilution and the Etest (AB Biodisk, Solna, Sweden), of azithromycin, clarithromycin and roxithromycin against Streptococcus pneumoniae and Streptococcus pyogenes. METHODS: Fresh clinical isolates collected from 36 hospital laboratories in 12 countries were evaluated using the Etest in the presence of carbon dioxide. The isolates were retested under ambient conditions (absence of carbon dioxide) using broth microdilution and/or the Etest. RESULTS: Carbon dioxide falsely elevated azithromycin, clarithromycin and roxithromycin MIC90S for S. pneumoniae, determined by the Etest, approximately 12-fold. Also, the azithromycin MIC90 for S. pyogenes was increased fourfold; the effect was less marked for clarithromycin and roxithromycin. When isolates were retested in the absence of carbon dioxide, using the Etest or microdilution, susceptibilities to azithromycin were comparable to those to clarithromycin (S. pneumoniae, 93.4% versus 91.3%; S. pyogenes, 96.4% versus 95.8%). Both organisms were less susceptible to roxithromycin (S. pneumoniae, 71.3%; S. pyogenes, 85.7%). An internal standard control, consisting of 50 isolates each of S. pneumoniae, S. pyogenes and Haemophilus influenzae, confirmed that azithromycin susceptibility testing resulted in falsely elevated MICs. CONCLUSIONS: Carbon dioxide falsely elevated azithromycin MICs for S. pneumoniae and S. pyogenes, with an apparent reduction in susceptibility. When the in vitro activity of azithromycin and other macrolides against S. pneumoniae and S. pyogenes is being evaluated, awareness of the pH effect is essential.
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PMID:The effect of carbon dioxide on susceptibility testing of azithromycin, clarithromycin and roxithromycin against clinical isolates of Streptococcus pneumoniae and Streptococcus pyogenes by broth microdilution and the Etest: Artemis Project-first-phase study. 1185 77


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