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)

The use of pharmacodynamic properties when formulating antibacterial administration guidelines can maximise the potential for efficacy while minimising the risk of toxicity. Aminoglycosides and quinolones demonstrate concentration-dependent bactericidal killing, which is maximised when their concentrations appreciably exceed their minimum inhibitory concentration (MIC) for an organism. beta-Lactams demonstrate time-dependent or concentration-independent bactericidal killing, which is maximised when the time that concentrations exceed the MIC is prolonged, regardless of the absolute levels attained. Methods of prolonging the time beta-lactam concentrations exceed the MIC include the following: interfering with excretion (e.g. probenecid); decreasing the dosage interval; increasing the dose; infusing continuously rather than by bolus; and choosing an agent with a prolonged elimination half-life. The optimal duration for exceeding the MIC varies with the infecting organism, site of infection, inoculum effect, and the immunocompetence of the host. Integration of the microbiological activity and pharmacokinetic properties enables estimation of the time that serum concentrations of various cephalosporins will exceed the MIC of a given organism, consequently allowing estimation of the relative potential for clinical success. Cefixime, a third generation oral cephalosporin with a long plasma elimination half-life, allowing once-daily administration, achieves serum concentrations that exceed the MIC of Haemophilus influenzae, Moraxella catarrhalis, Escherichia coli, and Group A streptococci for greater than 90% of the dosage interval, and the MIC of Streptococcus pneumoniae for 50 to 90% of the dosage interval.
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PMID:Choosing between the new cephalosporin antibiotics: a pharmacodynamic approach. 1014 87

The purpose of this study was to determine the prevalence of resistance to various antimicrobial drugs among Haemophilus influenzae isolates in Taiwan. Two hundred and ninety-six clinical isolates of H. influenzae were prospectively obtained from nine teaching hospitals throughout Taiwan, from June 1994 to April 1995. All isolates were examined for the presence of type b encapsulation and beta-lactamase production. Antibiotic susceptibility was determined by means of standard broth microdilution procedures. Twenty-three isolates (7.8%) were type b, and the overall rate of beta-lactamase production was 58.1% (172/296). The rates of resistance to antibiotics were 58.1% for ampicillin, 33.8% for trimethoprim-sulfamethoxazole, 20.6% for chloramphenicol, 27% for tetracycline, 6.7% for azithromycin, 3.4% for cefaclor, and 0.3% for cefuroxime. Cefixime, ceftriaxone, and ciprofloxacin were active against all H. influenzae isolates. Thirty (10.1%) of the 296 isolates were resistant to three drugs (ampicillin, chloramphenicol, and tetracycline), 16 of which (5.4%) were resistant to four drugs (ampicillin, chloramphenicol, tetracycline, and trimethoprim-sulfamethoxazole). There was a marked increase in the rates of ampicillin resistance and beta-lactamase production among H. influenzae isolates compared with a previous survey in Taiwan conducted 9 years ago. In addition, isolates with multiple drug resistance were also identified. Continued efforts are needed to monitor antibiotic resistance patterns of H. influenzae in the region.
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PMID:Prevalence of antimicrobial resistance among clinical isolates of Haemophilus influenzae in Taiwan. 1042 Jun 99

Over the last decade or so there has been a growing interest in routes of antimicrobial administration other than by the conventional intravenous route for institutionalized patients and for some outpatients. Both oral (PO) and intramuscular (IM) routes of administration are less costly than giving antimicrobial agents by vein (IV). In addition, fewer complications such as catheter-related sepsis and phlebitis are associated with non-IV routes of administration. Furthermore, a reduced-dosage, reduced-volume IM administration of ceftriaxone may provide a tolerable route of administration and equivalent bactericidal activities compared with higher dose IV ceftriaxone. The purpose of this study was to determine the time that the drug concentration remained in excess of the minimum inhibitory concentration (MIC) (T > MIC) and the duration of bactericidal activities of ceftriaxone one gram administered IV, ceftriaxone 250 mg given IM and cefixime 400 mg given orally against clinical isolates of Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis in adult volunteers. Single doses of each agent were administered and serum concentrations were collected over the standard dosing period of 24 h for all study regimens. Ceftriaxone, regardless of route of administration and dose, resulted in bactericidal activities and T > MIC for 100% of the dosing period for S. pneumoniae, H. influenzae, and M. catarrhalis. Cefixime maintained at least 50% T > MIC and bactericidal activity against both isolates each of H. influenzae and M. catarrhalis. Against both isolates of S. pneumoniae, cefixime achieved T > MIC for at least 50% of the dosing period, but did not maintain bactericidal activity. Reduced dose ceftriaxone given IM seems to be a viable alternative to ceftriaxone IV if the pathogen, susceptibility and infection site are known. Based on T > MIC exceeding 50% of the dosing interval, cefixime would be considered an effective alternative to IV therapy against common respiratory tract pathogens. Clinical studies need to be conducted to confirm these findings.
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PMID:Pharmacodynamics of ceftriaxone and cefixime against community-acquired respiratory tract pathogens. 1139 19

The in vitro activity of garenoxacin (BMS-284756) against 62 clinical Haemophilus influenzae isolates with different fluoroquinolone susceptibilities was determined by the microdilution susceptibility testing method and compared with the activities of other oral quinolones and nonquinolone oral antimicrobial agents. Cefixime presented the highest intrinsic activity (MIC at which 50% of the isolates tested were inhibited [MIC(50)], 0.01 microg/ml), followed by garenoxacin, moxifloxacin, and ciprofloxacin (MIC(50), 0.06 microg/ml), levofloxacin (MIC(50), 0.12 microg/ml), cefuroxime (MIC(50), 1.0 microg/ml), and amoxicillin-clavulanate (MIC(50), 1.0/0.5 microg/ml), amoxicillin (MIC(50), 2 microg/ml), azithromycin (MIC(50), 4 microg/ml), and erythromycin (MIC(50), 8 microg/ml). In strains with ciprofloxacin MICs of < or =0.06 microg/ml, ciprofloxacin and garenoxacin displayed similar MIC(50)s and MIC(90)s, one dilution lower than those of moxifloxacin and levofloxacin. For strains for which ciprofloxacin MICs were > or = 0.12 microg/ml, MIC(50)s were similar for the four quinolones tested, although garenoxacin presented the widest activity range (0.03 to 32 microg/ml) and the highest MIC at which 90% of the isolates tested were inhibited (16.0 microg/ml). For strains without amino acid changes in the quinolone resistance determining region (QRDR) of GyrA and ParC, garenoxacin MICs were < or =0.03 microg/ml; with a single amino acid change in GyrA, garenoxacin MICs were 0.06 to 0.12 microg/ml; with one amino acid change each in GyrA and ParC, garenoxacin MICs were 0.5 to 2.0 micro g/ml; one amino acid change in ParC combined with two amino acid changes in GyrA increased the MICs to > or = 4 microg/ml for all assayed quinolones. We conclude that garenoxacin has excellent activity against H. influenzae, although progressive acquired resistance was observed by step-by-step mutation in the QRDR of gyrA and parC.
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PMID:In vitro activities of garenoxacin (BMS-284756) against Haemophilus influenzae isolates with different fluoroquinolone susceptibilities. 1457 14

We tested abilities of ciprofloxacin, levofloxacin, gatifloxacin, moxifloxacin, amoxicillin, amoxicillin/clavulanate, cefixime, cefpodoxime, and cefdinir to select resistant mutants in 5 beta-lactamase positive and 5 beta-lactamase negative Haemophilus influenzae strains by single and multistep methodology. In multistep tests, amoxicillin, amoxicillin/clavulanate and cefpodoxime exposure did not cause >4-fold minimum inhibitory concentration (MIC) increase after 50 days. One mutant selected by cefdinir had one amino acid substitution (Gly490Glu) in PBP3 and became resistant to cefdinir. Cefixime exposure caused 8-fold MIC-increase in 1 strain with TEM but the mutant remained cefixime susceptible and had no alteration in PBP3 or TEM. Among 10 strains tested, ciprofloxacin, moxifloxacin, gatifloxacin, levofloxacin caused >4-fold MIC increase in 6, 6, 5, and 2 strain, respectively. Despite the increases in quinolone MICs, none of the mutants became resistant to quinolones by established criteria. Quinolone selected mutants had quindone resistance-determining region (QRDR) alterations in GyrA, GyrB, ParC, ParE. Four quinolone mutants had no QRDR alterations. Among beta-lactams cefdinir and cefixime selected one mutant each with higher MICs however amoxicillin, amoxicillin/clavulanate, and cefpodoxime exposure did not select resistant mutants.
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PMID:In vitro selection of resistance in haemophilus influenzae by 4 quinolones and 5 beta-lactams. 1513 97


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