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PubMed1988

[Kinetics of ofloxacin-amoxicillin and ofloxacin-clavulanic acid combinations against pathogenic bacteria of the respiratory tract].

Ofloxacin exhibit a good activity against the pathogen bacteria of the respiratory tract, except for S. pneumoniae. Its use is interesting because it has a good diffusion into respiratory tissues. However, the combination with an another antibiotic was necessary to spread the activity spectrum and to prevent the resistant variants. By the new killing curve checkerboard method, these 2 combinations are studied against 8 strains: 4 H. influenzae (2 beta-lactamase producers), 2 S. pneumoniae and 2 K. pneumoniae, at 0, 2, 4, 6 and 24 hours, a viable bacteria counting is executed by a microdilution method and is subcultured with a Steers-type multiple inoculator. With K. pneumoniae, ofloxacin has a dose dependent bactericidal activity which is maximum at 1 mg/l, While augmentin has a time-dependent activity. In the combination the synergy is rare. With H. influenzae, the results are the same; the bactericidal activity is less rapid but it is better than the ones with amoxicillin and clavulanic acid. With S. pneumoniae, the 2 antibiotics have the same activity. No antagonism is observed. And the antibiotic which has a better bactericidal activity determine the viable bacteria count.

Amoxicillin↗
PubMed1988

[Sensitivity to clavulanic acid of Escherichia coli isolated at the Henri Mondor hospital in 1986 according to phenotypes of beta-lactam antibiotic resistance].

Susceptibility to Augmentin (AUG) was studied as a function of resistance phenotypes toward amoxicillin (AMX), carbenicillin (CAR), cephalothin (CFT) and cefotaxime (CTX) for 1817 strains of Escherichia coli isolated at Henri-Mondor hospital during 1986. For strains susceptible to the 4 beta-lactams (phenotype SSSS: 66%), the median zone diameter observed with AUG was 26.4 mm. It was slightly inferior (22.1) for acquired - penicillinase producing strains (phenotype RRSS: 21.5%), but zone diameters were greater than or equal to 21 mm for over than 75% of these strains. Strains of phenotype RRIS (6%), probably high penicillinase-producers, were generally intermediate to AUG (median zone diameter: 17.8), showing partial inhibition of enzyme by clavulanic acid. Cephalosporinase hyperproducers mutants (phenotype RSRS: 4%) and strains with a RRRS phenotype (2.5%), probably penicillinase and cephalosporinase producers, were resistant to AUG (median zone diameters: 15.6 and 12.6 mm). Among rarely observed phenotypes, some were readily integrated to major phenotypes: RSIS, ISRS and ISIS to phenotype RSRS; RIRS to phenotype RRRS; IISS to phenotype RRSS; apparently "aberrants" phenotypes (ISSS, RSSS, SSIS, SSRS) required interpretation of results as a function of observed zone diameters and at time a verification of tests. This study confirms the in vitro activity of AUG on penicillinase producing E. coli; in addition simultaneous reading of zone diameters observed with AMX, CAR, CFT and CTX, permitted to infer the probable mechanism of resistance to beta-lactams and therefore to correct possible discrepancies observed in antibiogram results.

Amoxicillin↗
PubMed2003

Crystal structure and mechanistic implications of N2-(2-carboxyethyl)arginine synthase, the first enzyme in the clavulanic acid biosynthesis pathway.

The initial step in the biosynthesis of the clinically important beta-lactamase inhibitor clavulanic acid involves condensation of two primary metabolites, D-glyceraldehyde 3-phosphate and L-arginine, to give N2-(2-carboxyethyl)arginine, a beta-amino acid. This unusual N-C bond forming reaction is catalyzed by the thiamin diphosphate (ThP2)-dependent enzyme N2-(2-carboxyethyl)arginine synthase. Here we report the crystal structure of N2-(2-carboxyethyl)arginine synthase, complexed with ThP2 and Mg2+, to 2.35-A resolution. The structure was solved in two space groups, P2(1)2(1)2(1) and P2(1)2(1)2. In both, the enzyme is observed in a tetrameric form, composed of a dimer of two more tightly associated dimers, consistent with both mass spectrometric and gel filtration chromatography studies. Both ThP2 and Mg2+ cofactors are present at the active site, with ThP2 in a "V" conformation as in related enzymes. A sulfate anion is observed in the active site of the enzyme in a location proposed as a binding site for the phosphate group of the d-glyceraldehyde 3-phosphate substrate. The mechanistic implications of the active site arrangement are discussed, including the potential role of the aminopyrimidine ring of the ThP2. The structure will form a basis for future mechanistic and structural studies, as well as engineering aimed at production of alternative beta-amino acids.

Amino Acids↗
PubMed1991

Comparative efficacies of ciprofloxacin, amoxicillin, amoxicillin-clavulanic acid, and cefaclor against experimental Streptococcus pneumoniae respiratory infections in mice.

Experimental respiratory infections were established in mice by intranasal inoculation of Streptococcus pneumoniae. Inoculation of 10(7) CFU of either S. pneumoniae 1629 or S. pneumoniae 7 produced a fatal pneumonia in nontreated mice 2 to 3 days after infection. Oral therapy was commenced 1 h after infection and was continued three times a day for 2 days. The doses used in mice produced peak concentrations in serum and lung tissue similar to those measured in humans. Ciprofloxacin failed to eliminate either strain of pneumococcus from mouse lungs at any of the doses tested (40, 80, or 160 mg/kg of body weight) by the end of therapy (33 h). Mice that received ciprofloxacin at 160 mg/kg were clear of S. pneumoniae 7 5 days later, whereas persistence and regrowth of S. pneumoniae 1629 resulted in the death of 20% of animals treated with ciprofloxacin. Therapy with cefaclor (20 mg/kg) produced an effect similar to that of ciprofloxacin. In contrast, amoxicillin (10 and 20 mg/kg) and amoxicillin-clavulanic acid (10/5 and 20/10 mg/kg) were significantly (P less than 0.05) more effective in eliminating both strains of S. pneumoniae from the lungs by the end of therapy and, by 168 h, had prevented mortality in 80 to 100% of treated animals. The efficacy of ciprofloxacin against these experimental pneumococcal respiratory infections was poor, despite good penetration into lung tissue, and is a reflection of the low in vitro activity of the quinolone against S. pneumoniae, one of the most common pathogens in community-acquired pneumonia.

Amoxicillin↗
PubMed1978

Kinetic studies on the inactivation of Escherichia coli RTEM beta-lactamase by clavulanic acid.

The kinetic details of the irreversible inactivation of the Escherichia coli RTEM beta-lactamase by clavulanic acid have been elucidated. Clavulanate is destroyed by the enzyme and simultaneously inhibits it by producing two catalytically inactive forms. One of these is transiently stable and decomposes to free enzyme (k = 3.8 X 10(-3) S-1), while the other corresponds to an irreversibly inactivated form. The transient complex is formed from the Michaelis complex at a rate (k approximately 3 X 10(-2) S-1) which is some threefold faster than the rate of formation of the irreversibly inactivated complex. The transient complex is, therefore, the principle enzyme form present after short time periods. In the presence of excess clavulanate, however, all the enzyme accumulates into the irreversibly inactivated form. The number of clavulanate turnovers that occur prior to complete enzyme inactivation is 115.

Anti-Bacterial Agents↗
PubMed1986

Timentin (ticarcillin and clavulanic acid) in combination with aminoglycosides in the treatment of febrile episodes in neutropenic children.

Timentin (ticarcillin + clavulanic acid) combined with an aminoglycoside usually netilmicin, was given to 33 children with neutropenic haematological malignancies. The combination of Timentin and aminoglycoside was effective treatment in 27 (87%) of 31 febrile episodes. There were four failures and three results which could not be interpreted. Bacteriological investigations were positive in 13 patients, three strains were resistant to ticarcillin but all were sensitive to Timentin. Clinical success, based upon reduction of fever within 48 h of treatment, was identical whether an organism was isolated or not. The combination of Timentin plus aminoglycoside was very successful and represents one of the best combinations available for empirical treatment for febrile neutropenic children.

Adolescent↗
PubMed1985

[Laboratory and clinical studies on BRL 25000 (clavulanic acid -amoxicillin) granules in the pediatric field].

Laboratory and clinical studies on BRL 25000 granules (containing clavulanic acid (CVA) 1 part plus amoxicillin (AMPC) 2 parts) were performed in infections in the pediatric field. Following oral administration of BRL 25000 granules at a dose of 15 mg/kg body weight, the maximum serum levels of AMPC and CVA achieved approximately 1 hour after dosing were 8.68 micrograms/ml and 4.09 micrograms/ml and declined thereafter with half-lives of 1.39 and 0.80 hours, respectively. The 6-hour urinary recovery rates for AMPC and CVA were 55.81% and 26.08%, respectively. Following oral administration of BRL 25000 granules at a dose of 22.5 and 24.3 mg/kg body weight, the serum levels of AMPC and CVA peaked at 7.37 micrograms/ml and 2.98 micrograms/ml after 1 hour and declined with half-lives of 2.52 and 0.99 hours, respectively. The 6-hour urinary recovery rates for AMPC and CVA were 40.02% and 13.95%, respectively. The clinical efficacy of BRL 25000 granules was evaluated in 23 patients with upper respiratory tract infections, skin infections, etc. Overall the clinical efficacy was good to excellent in 21/23 (91.3%). The bacteriological and clinical efficacy rates for beta-lactamase producing bacteria and non-producing bacteria were 50% (1/2) and 100% (12/12), respectively. Side effects were observed in 1 patient, who experienced mild diarrhea and abdominal pain but not of a severe nature.

Administration, Oral↗
PubMed1991

Ampicillin-sulbactam and ticarcillin-clavulanic acid: a comparison of their in vitro activity and review of their clinical efficacy.

Sulbactam (SB) and clavulanic acid (CA) are irreversible inhibitors of the beta-lactamases in the Richmond and Sykes classes II-VI. When combined with ampicillin and ticarcillin, SB and CA, respectively, extend the spectrum of activity of these penicillins to include some beta-lactamase-producing aerobes (Enterobacteriaceae, Hemophilus influenzae, staphylococci) and anaerobes (Bacteroides fragilis group) which would otherwise be resistant. Neither effectively inhibits the class I beta-lactamases frequently produced by Pseudomonas aeruginosa, Enterobacter, and Serratia, in part explaining the resistance observed with these organisms. Clinically, both agents were as effective as the comparative therapies in all but two of the trials reviewed. Given the current data, the decision to add these agents to the formulary should be based on hospital resistance patterns and on the cost of these antimicrobials in comparison to conventional therapies.

Ampicillin↗
PubMed1999

[Comparison between penicillin and amoxicillin-clavulanic acid for the treatment of recurrent tonsillopharyngitis in childhood].

Fifty-one children aged 2-14 years with recurrent tonsillopharyngitis, presenting dysphagia, fever and lymphadenitis, with more than two similar episodes in the last three years and showing a beta-hemolytic group A streptococci in the pharyngeal smear, were studied. They underwent random treatment for ten days with phenoxymethylpenicillin (40-60 mg/kg/day) (n = 28) or amoxicillin-clavulanic acid (20-40 mg/kg/day) (n = 23) taken orally three times a day. Clinical and bacteriological tests were carried out at 10 days and 2, 6 and 12 months post-treatment. The clinical and bacteriological results showed the superiority of the amoxicillin-clavulanic acid treatment both in the short term (disappearance of symptoms) and in the long term (decrease in recurrence). These results support the idea that betalactamases produced by the pharyngeal flora play an important role in the failures of penicillin.

Adolescent↗
PubMed1987

[Clavulanic acid. Its effect on Staphylococcus aureus other than its inhibitory effect on beta-lactamases].

The influence of clavulanic acid (CA) on growth kinetics of Staph. aureus strains with MIC values (minimal inhibitory concentration) of penicillin (Pc) between 0,06 and 1 024 IU/ml was examined. Furthermore, it was tried to select mutants of the parent strains with increased resistance to CA and, in the affirmative case, to find out a relationship between Pc and CA resistance. The experiments showed that CA in subinhibitory concentrations induced a considerable increase of the latent phase of Pc sensitive strains but less of the Pc resistant ones. CA delayed also the generation time but this effect was apparently independent of Pc resistance. Successive subculturing of strains in gradually increasing CA concentrations resulted in an increase of CA resistance by a factor of 4 to 8 compared with that of the parent strains. In parallel, the Pc resistance increased by a factor of 16 to 64, however only in case of strains originally sensitive to Pc. A synergistic or additive effect of CA and Pc evaluated by the index of the fractional inhibitory concentration (IFIC) was not only shown in Pc resistant but also in Pc sensitive strains. This effect was equally demonstrable in strains with increased CA resistance. In this case, however, the MIC of Pc in the presence of CA was increased by a factor of 32 to 64 in originally Pc sensitive strains and by a factor of 2 to 4 in the originally Pc resistant ones. These results indicate a possible selection of CA resistant strains with an increased Pc resistance.

Clavulanic Acids↗
PubMed1998

[Prospective and comparative study between cefuroxime, ceftriaxone and amoxicillin-clavulanic acid in the treatment of community-acquired pneumonia].

Among community-acquired infections, pneumonia is still a large health problem which is of great interest mainly due its high mortality and morbidity. From 1991 to 1997, 409 patients who had been diagnosed with community-acquired pneumonia and had been admitted to the internal medicine service of a university hospital were prospectively studied. The patients were classified into three groups according to the random antibiotic treatment they had received (ceftriaxone, cefuroxime or amoxicillin-clavulanic acid). The initial characteristics of the patients with regard to epidemiology, clinical description and critical situation were similar in all the groups studied. A total of 36.9% of the cases were documented microbiologically, with the most frequently isolated pathogens being Streptococcus pneumoniae and Haemophilus influenzae. The recovery rate was 92.2% and three patients had a recurrence of pneumonia. Global mortality was 5.8%. No statistically significant differences were found in the evolution of patients treated with cefuroxime, ceftriaxone or amoxicillin-clavulanic acid, with the latter representing an empirical treatment of choice for community-acquired pneumonia.

Adolescent↗
PubMed1984

[In vitro activity of the amoxicillin-clavulanic acid combination on anaerobic bacteria. Comparison with amoxicillin, lamoxactam and metronidazole].

Minimal inhibitory concentrations (MIC) of the combination amoxicillin + clavulanic acid (AAC) (2/1 w/w) on 84 strains of obligate anaerobes were measured by the agar diffusion method and compared to those of amoxicillin (AMO), lamoxactam (LAM) and metronidazole (MET). For the 47 Bacteroides fragilis strains tested, the mode MIC was 0.5 microgram/ml with AAC, 1-2 with MET, 0.5-1 with LAM and 8-16 with AMO. A similar range of activity was found on the 16 other strains of Bacteroides sp.. AAC and AMO have a comparable activity on Clostridium perfringens (mode MIC 0.016-0.032 microgram/ml), superior to that of LAM (mode MIC 0.125) and MET (mode MIC 0.5). AAC and AMO have an almost identical activity on Peptococci and Peptostreptococci, the MIC for both drugs being less than 0.125 microgram/ml. A similar activity was found for LAM and MET.

Amoxicillin↗
PubMed1985

Ticarcillin plus clavulanic acid (Timentin) therapy for osteomyelitis.

Timentin is an exciting new antibiotic agent that is a combination of ticarcillin and clavulanic acid. Forty-seven patients with osteomyelitis received 3.1 g of Timentin intravenously every six hours. The mean duration of therapy was 32 days. The diagnosis was made by bone biopsy; bone biopsy was repeated at the completion of therapy. The bacterial etiology was predominately gram-positive organisms. Of the organisms isolated, Staphylococcus aureus was the most common isolate and represented 39 percent of the total isolates. Streptococcus species were isolated in 13 percent, Group D Enterococcus in 15 percent, Pseudomonas aeruginosa in 10 percent; 23 percent of the isolates were other gram-negative organisms. All but one organism were initially sensitive to Timentin. Three resistant organisms were isolated during therapy. Twenty-seven patients were classified as having a cure, based on no growth on repeat bone biopsy cultures and clinical signs of bone healing. Twenty-two patients returned for follow-up (one to nine months after therapy) and had no evidence of infection; however, because of the short follow-up period, these patients were classified as showing improvement. Six patients had adverse reactions to Timentin: two had mild allergic phenomena and two had prolonged bleeding times. In all four, therapy was discontinued. Two patients had a transient, mild elevation in the level of serum glutamic-pyruvic transaminase (less than twice normal levels). This new agent looks exciting for therapy of both gram-positive and gram-negative bacterial osteomyelitis.

Adolescent↗
PubMed1991

Clinical evaluation of ticarcillin, with clavulanic acid, and gentamicin in the treatment of febrile episodes in neutropenic children.

To assess the clinical efficacy of ticarcillin, with clavulanic acid, and gentamicin, we conducted a prospective one year study of febrile episodes in neutropenic children. Seventy-five episodes were evaluated in 42 children. The response rate was 32% during persistent neutropenia, whilst another third of episodes responded with neutrophil recovery. Positive blood cultures occurred in 21 episodes and 20 of 24 micro-organisms belonged to the 'community' flora, i.e. organisms carried by healthy people (Streptococcus pneumoniae, Staphylococcus aureus, Branhamella catarrhalis and Escherichia coli). The route of pathogenesis was endogenous in 76% of the patients. There was a substantial superinfection-related morbidity (14%) and mortality (7%), related to emergence of resistance during and after parenteral antibiotic administration. The poor clinical response, combined with emergence of resistance, lead to the conclusion that this combination is of limited value as a first line regimen for neutropenic patients.

Child↗