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

The antibacterial effects produced by ticarcillin disodium plus clavulanate potassium, a combination of the broad-spectrum penicillin ticarcillin, and the beta-lactamase inhibitor clavulanic acid as the potassium salt, have been measured in vitro and in experimental infection studies. The presence of clavulanic acid resulted in a significant enhancement of the activity of ticarcillin against a wide range of beta-lactamase-producing bacteria. These included ticarcillin-resistant strains of Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, P. vulgaris, Yersinia enterocolitica, and the anaerobe Bacteroides fragilis. In addition, beta-lactamase-producing isolates of Hemophilus influenzae, Branhamella catarrhalis, Neisseria gonorrhoeae, and Staphylococcus aureus were susceptible to ticarcillin and clavulanate. Clavulanic acid did not influence the activity of ticarcillin against ticarcillin-susceptible bacteria. The bactericidal effects of the antibiotic combination were measured in an in vitro kinetic model in which the drug concentrations were varied to simulate those measured in humans after intravenous dosing with ticarcillin (3.0 g) and clavulanate potassium (100 mg clavulanic acid). In these tests, ticarcillin plus clavulanic acid had pronounced bactericidal activity against ticarcillin-resistant bacteria. The protection of ticarcillin by clavulanic acid from inactivation by bacterial beta-lactamases in vivo was demonstrated in experimental infection models in which the efficacy of the ticarcillin plus clavulanic acid combination against infections caused by beta-lactamase-producing bacteria was correlated with the presence of effective concentrations of both antibiotic and inhibitor at the site of infection.
 ...
PMID:Antibacterial activity of ticarcillin in the presence of clavulanate potassium. 387 80

Resistance of bacteria to beta-lactam antibiotics has become a serious problem in the past several decades. Virtually all Staphylococcus aureus, and many Hemophilus influenzae, Branhamella catarrhalis, Neisseria gonorrhoeae, Enterobacteriaceae, and Bacteroides species possess beta-lactamases that hydrolyze penicillins and cephalosporins. The most common plasmid-mediated beta-lactamase is the TEM enzyme (Richmond-Sykes type IIIa), which is present in Hemophilus, Neisseria, and Enterobacteriaceae. One technique to overcome bacterial resistance has been the development of beta-lactamase inhibitors. Clavulanic acid is a beta-lactamase inhibitor that inhibits the beta-lactamases of S. aureus, Hemophilus, Neisseria, Branhamella, Eschericia coli, Klebsiella, and Bacteroides. Clavulanate acts as a "suicide" inhibitor, forming a stable enzyme complex that binds to serine at the active site of the enzyme. Clavulanate readily crosses the outer cell wall of most Enterobacteriaceae to interact with beta-lactamases in the periplasmic space. Clavulanate does not inhibit beta-lactamases such as the Richmond-Sykes type I enzymes found in Pseudomonas aeruginosa, Enterobacter, and Citrobacter species, which are inducible enzymes that function primarily as cephalosporinases.
 ...
PMID:Contribution of beta-lactamases to bacterial resistance and mechanisms to inhibit beta-lactamases. 390 41

Clavulanic acid is a beta-lactam antibiotic which, although it has little intrinsic activity, is a potent inhibitor of bacterial beta-lactamases. When combined with amoxycillin its range of activity includes penicillinase-producing strains of Staphylococcus aureus and many of the beta-lactamase-producing strains of Gram-negative bacilli. Bacteria sensitive to augmentin include amoxycillin-resistant strains of Haemophilus influenzae and Escherichia coli, in addition strains of Klebsiella aerogenes, Proteus mirabilis, Proteus vulgaris and Bacteroides fragilis are usually sensitive. The beta-lactamases produced by Enterobacter spp, Proteus morgani, Serratia marcescens and Pseudomonas aeruginosa are less susceptible to clavulanic acid and these bacteria are usually resistant to augmentin (1).
 ...
PMID:Augmentin: laboratory studies. 676 61

Bacterial resistance to the beta-lactam group of antibiotics is frequently due to the production of beta-lactamase which brings about the inactivation of the antibiotic. Clavulanic acid is a naturally occurring inhibitor of beta-lactamase which is capable of rendering penicillin- and cephalosporin-resistant organisms sensitive. The compound is obtained by fermentation from Streptomyces clavuligerus. Clavulanic acid shows some structural similarity to the penicillins and cephalosporins and functions as a progressive inhibitor of a wide range of beta-lactamases including those found in Escherichia coli, Klebsiella aerogenes, Proteus species, Bacteroides fragilis, Haemophilus influenzae, Neisseria gonorrhoeae and Staphylococcus aureus. Clavulanic acid is well absorbed when given by mouth and a formulation with amoxycillin (Augmentin; Beechams) is now available for clinical use.
 ...
PMID:The history and background of Augmentin. 697 4

A study was done to determine susceptibilities of Haemophilus influenzae that were obtained in our laboratory in 1994 to new quinolones (NQ) and other drugs. The results were as follows; 1. Among the 300 isolates, the detection frequency of NQ-resistant strains was 8.7% (26 strains), including isolates from chronic lower respiratory tract infections (22 strains) and those from middle meatus of nose (2 strains), etc. NQ-resistant strains were not isolated from children. 2. The cross resistance was studied for different NQs against NQ-resistant strains. Clavulanic acid/amoxicillin, cefteram, cefpodoxime, cefditoren, cefodizime (CDZM) and cefpirome showed strong antimicrobial activities against NQ-resistant strains. MIC90 of CEPs against all isolated strains including NQ-resistant strains and beta-lactamase producers was low. And the MIC90 of CDZM was < or = 0.025 microgram/ml, which was the lowest among all the antibiotics tested. 3. We found 47 strains (15.7%) of beta-lactamase producers among the 300 isolates, the frequency of beta-lactamase producing strains was high among strains obtained from children.
 ...
PMID:[Study of clinically isolated new quinolones-resistant Haemophilus influenzae. Part 1]. 747 25

Classification schemes for gram-negative beta-lactamases are presented, mechanisms by which beta-lactamases inactivate beta-lactam antibiotics are reviewed, and methods for assessing the efficiency of beta-lactamase inhibitors are evaluated. Beta-lactamases are commonly produced by Staphylococcus species, the Enterobacteriaceae, Pseudomonas aeruginosa, Acinetobacter species, and some anaerobes. Currently available beta-lactamase inhibitors are thought to be "suicide inhibitors" that form stable complexes between the bacterial beta-lactamase and the beta-lactamase inhibitor in a multistep chemical reaction. Each step can be quantitated; however, the overall process is difficult to measure. Thus, a comparative evaluation of commercially available beta-lactamase inhibitors is extremely difficult and must be done under standardized test conditions. In general, sulbactam, clavulanate, and tazobactam are all potent inhibitors of staphylococcal penicillinase; chromosomal beta-lactamases produced by Bacteroides species, Proteus vulgaris, Haemophilus influenzae, Neisseria gonorrhoeae; and type IV enzymes of Klebsiella species. Although sulbactam possesses activity against TEM-1 and TEM-2 beta-lactamases, it does not have reliable activity against SHV-1 beta-lactamases. Clavulanate and tazobactam are potent inhibitors of both TEM and SHV-1 beta-lactamases. P. aeruginosa and some Enterobacteriaceae produce an inducible, extremely potent, broad-spectrum enzyme (type I beta-lactamase). Tazobactam is the only currently available. beta-lactamase inhibitor with activity against type I beta-lactamases; however, some enzymes are not inhibited by tazobactam.
 ...
PMID:Combination beta-lactam and beta-lactamase-inhibitor products: antimicrobial activity and efficiency of enzyme inhibition. 760 85

Inhibitor combinations provide one strategy to overcome beta-lactamase-mediated resistance. Their success depends, obviously, on the inhibitor being able to bind and inactivate the beta-lactamase molecules. Clavulanate, sulbactam and tazobactam are irreversible inactivators of many beta-lactamases, forming covalent complexes which resist hydrolysis. 'Suicide' kinetics are seen with some, but not all, enzymes. All three compounds inactivate staphylococcal penicillinase, the chromosomal beta-lactamases of Proteus vulgaris and Bacteroides spp., and the Class IV beta-lactamases present in some klebsiellae. Tazobactam, but not the other compounds, has moderate activity against some Class I (AmpC) chromosomal beta-lactamases, notably that of Morganella morganii, but not that of Enterobacter cloacae. Both clavulanate and tazobactam are strong inhibitors of the widely distributed TEM and SHV plasmid-mediated beta-lactamases; sulbactam is a weaker inhibitor. Other factors, aside from the affinity of the inhibitor for the enzyme, co-determine the success or failure of inhibition. Potentiation is most readily achieved if little enzyme is produced, and if the organism is very permeable to the inhibitor. Thus, resistance to inhibitor combinations is rare in strains of Haemophilus influenzae and Neisseria gonorrhoeae that produce TEM-beta-lactamase, but is commoner in enterobacteria that produce this enzyme, since these are less permeable and sometimes manufacture very large amounts of enzyme. The partner beta-lactam agent is also important. Irrespective of the inhibitor used, piperacillin is easier to protect against TEM beta-lactamases and the M. morganii Class I enzyme than are ampicillin, amoxycillin or ticarcillin. This may relate to the lower affinity of piperacillin for these enzymes, or to its greater affinity for the bacterial penicillin-binding proteins. Finally, pH can affect the degree of inhibition achieved with sulphones for some beta-lactamases, notably TEM-1.
 ...
PMID:Determinants of the activity of beta-lactamase inhibitor combinations. 844 36

The present study was undertaken to determine the in vitro drug resistance of Haemophilus influenzae (68 isolates) and H. parainfluenzae (17 isolates). The tests susceptibility to Ampicillin, Amoxicilin/Clavulanic Acid, Cefaclor, Cefuroxime, Cotrimoxazole, Aztreonam, Ceftriaxone, Tetracycline, Ciprofloxacin, Rifampicin and Chloramphenicol were performed with a standard disk-diffusion method. The NCCLS methodology and susceptibility interpretative criteria were applied as described by the disk manufacturer. Beta-lactamase production was detected with nitrocefin impregnated disk (Cefinase, BBL Microbiology System). Resistance in nosocomially acquired Haemophilus isolates to several antibiotics was observed. Of the Haemophilus isolates 28.2% were Ampicillin in resistant, all were susceptible to the combination of Amoxicillin/Clavulanic acid. The Ampicillin-resistant strains were beta-lactamase producers. We observed the high resistance (70.1%) to Tetracycline and (28.2%) to SXT (Cotrimoxazole). All isolates of Haemophilus were susceptible to Ciprofloxacin. The low resistance percentages to Rifampin (1.2%), Aztreonam (3.5%) and Chloramphenicol (3.5%) was observed.
 ...
PMID:[Resistance of Haemophilus sp. to antibiotics]. 959 39

Acidaminococcus fermentans belongs to the group of strictly anaerobic gram-negative cocci. All previously described Acidaminococcus strains are susceptible to beta-lactam antibiotics. An A. fermentans strain (RYC-MR95) resistant to penicillin and expanded-spectrum cephalosporin (amoxicillin and cefotaxime MICs, 64 microgram/ml) was isolated from a human perianal abscess. A fragment encoding a beta-lactamase from genomic DNA was cloned in Escherichia coli K-12 strain HB101, and the recombinant strain expressed resistance to amoxicillin (MIC, 1,024 microgram/ml) and cefotaxime (MIC, 4 microgram/ml). Clavulanic acid decreased the MICs to 8 and 0.03 microgram/ml, respectively. Analysis of the nucleotide sequence revealed a new class A beta-lactamase, ACI-1. In accordance with its biochemical properties, we propose to assign ACI-1 to functional group 2be. The ACI-1 enzyme (estimated pI 4.3) had <50% amino acid identity with any other class A beta-lactamases, the closest being ROB-1 from Haemophilus influenzae (44%). ACI-1 was closer to class A beta-lactamases from some gram-positive organisms (41 to 44% amino acid identity with Bacillus beta-lactamases) than to most class A enzymes from gram-negative organisms (TEM-1, 24.6%). The aci1 gene had a G+C content of 42.1%, in contrast with 56% G+C content for genomic DNA from A. fermentans, thus suggesting that aci1 may have been obtained by horizontal gene transfer.
 ...
PMID:ACI-1 from Acidaminococcus fermentans: characterization of the first beta-lactamase in Anaerobic cocci. 1103 38

One thousand seventy-three bacterial isolates were collected from patients with community acquired respiratory tract infections (CARTI) in 11 Latin American centers (7 countries) during 1997 and 1998. They were tested against numerous antimicrobial agents by the reference broth microdilution method as part of the ongoing multinational SENTRY Antimicrobial Surveillance Program. Among Streptococcus pneumoniae (553 isolates), approximately 61% were susceptible to penicillin. There was a great variation of the penicillin susceptibility rates among participating countries. The highest susceptibility rates were found in Argentina (76.7%) and Brazil (71.9%), while the lowest rate of penicillin susceptibility was detected in Mexico (33.3%). High level resistance to penicillin and resistance to cefotaxime were observed in nearly 10% of the isolates. The newer quinolones, levofloxacin (MIC(90) 2 microg/mL) and gatifloxacin (MIC90 0.5 microg/mL), were active against 100% of the isolates tested. Among the other non-beta-lactams drugs tested, the rank order of susceptibility against the pneumococci was: chloramphenicol (93.9%)>clindamycin (93.2%)> azithromycin (89.1%) > clarithromycin (88.7%)>tetracycline (78.5%)> trimethoprim/sulfamethoxazole (55.7%). The percentage of Haemophilus influenzae (361 isolates) isolates resistant to amoxicillin was 12. 7% (beta-lactamase positive). Among Moraxella catarrhalis (159 isolates) isolates, only 8.2% were susceptible. Clavulanic acid restored the activity of amoxicillin against both species. Trimethoprim/sulfamethoxazole was active against only 59.5% of H. influenzae, while susceptibility to this compound among M. catarrhalis was 96.1%. All other compounds tested were active against>95% of H. influenzae and M. catarrhalis isolates. These species were susceptible to levofloxacin (MIC90 < or = 0.5 microg/mL for both) and gatifloxacin (MIC90 < or = 0.03 microg/mL for both) with very low MICs. Our results indicate that penicillin resistance rates are particularly high among pneumococci in some countries. The newer fluoroquinolones show an excellent potency and spectrum against pathogens causing community acquired respiratory infections in Latin America.
 ...
PMID:Prevalence of antimicrobial resistance among respiratory tract isolates in Latin America: results from SENTRY antimicrobial surveillance program (1997-98). 1106 56


<< Previous 1 2