Ceftibuten (7432-S, SCH 39720): comparative antimicrobial activity against 4735 clinical isolates, beta-lactamase stability and broth microdilution quality control guidelines

Discovery of VNRX-7145 (VNRX-5236 Etzadroxil): An Orally Bioavailable β-Lactamase Inhibitor for Enterobacterales Expressing Ambler Class A, C, and D Enzymes

A major antimicrobial resistance mechanism in Gram-negative bacteria is the production of β-lactamase enzymes. The increasing emergence of β-lactamase-producing multi-drug-resistant “superbugs” has resulted in increases in costly hospital Emergency Department (ED) visits and hospitalizations due to the requirement for parenteral antibiotic therapy for infections caused by these difficult-to-treat bacteria. To address the lack of outpatient treatment, we initiated an iterative program combining medicinal chemistry, biochemical testing, microbiological profiling, and evaluation of oral pharmacokinetics. Lead optimization focusing on multiple smaller, more lipophilic active compounds, followed by an exploration of oral bioavailability of a variety of their respective prodrugs, provided 36 (VNRX-7145/VNRX-5236 etzadroxil), the prodrug of the boronic acid-containing β-lactamase inhibitor 5 (VNRX-5236). In vitro and in vivo studies demonstrated that 5 restored the activity of the oral cephalosporin antibiotic ceftibuten against Enterobacterales expressing Ambler class A extended-spectrum β-lactamases, class A carbapenemases, class C cephalosporinases, and class D oxacillinases.

Oral cephalosporin and β-lactamase inhibitor combinations for ESBL-producing Enterobacteriaceae urinary tract infections

ESBL-producing Enterobacteriaceae as uropathogens have given rise to a sizeable amount of global morbidity. Community and hospital surveillance studies continue to report increasing proportions of these organisms as causes of urinary tract infection (UTI). Due to limited treatment options and the presence of cross-resistance amongst oral antibiotics of different classes, patients often require IV therapy, thereby increasing healthcare costs and reducing the effectiveness of delivering healthcare. Oral cephalosporin antibiotics are well known for their ability to achieve high urinary concentrations, in addition to achieving clinical success for treatment of uncomplicated UTI with a drug-susceptible pathogen. Novel cephalosporin/β-lactamase inhibitor combinations have been developed and demonstrate good in vitro activity against ESBL-producing isolates. A pooled analysis of in vitro activity of existing oral cephalosporin/clavulanate combinations in ESBL-producing Enterobacteriaceae has shown MIC50s of 0.5-1, 0.125-1 and 0.25 mg/L for cefpodoxime, ceftibuten and cefixime, respectively. A novel cyclic boronic acid β-lactamase inhibitor, QPX7728, was able to produce MIC50 values of 0.5 and ≤0.06 mg/L when paired with cefpodoxime and ceftibuten, respectively. Other novel combinations, cefpodoxime/ETX0282 and ceftibuten/VNRX7145, have also demonstrated excellent activity against ESBL producers. Clinical trials are now awaited.

Concentrations of ceftibuten in plasma and the respiratory tract following a single 400 mg oral dose

Concentrations of ceftibuten in bronchial mucosa, epithelial lining fluid (ELF) and alveolar macrophages were determined from samples taken from 15 subjects at bronchoscopy following a single 400 mg oral dose. Concentrations at all sites were determined using a microbiological assay method which was unaffected by the trans-isomer of ceftibuten. The time from dosage to bronchoscopy ranged from 1.4 to 20.3 h and the subjects were analysed in three groups according to time after dosing. Group A had a mean time since dosing of 1.9 h with mean serum, mucosal and ELF concentrations of 15.2 mg/l, 5.7 mg/kg and 1.6 mg/l. Group B had a mean time of 6.5 h after dosing with mean serum, mucosal and ELF concentration of 14.0 mg/l, 3.2 mg/kg and 1.6 mg/l. Group C had a mean time of 13.3 h with mean serum, mucosal and ELF levels of 4.1 mg/l, 1.8 mg/kg and 1.2 mg/l. Macrophage-related ceftibuten could only be detected in two subjects. These levels are related to the minimum inhibitory concentrations of ceftibuten against common respiratory pathogens with the exception of Strep. pneumoniae.

Interpretive criteria of ceftibuten disk diffusion susceptibility tests according to the DIN 58 940 method

OBJECTIVE

This study aimed to establish interpretive criteria for agar diffusion tests with ceftibuten disks according to DIN standards.

METHODS

Minimal inhibitory concentrations (MICs) and inhibition zones produced by ceftibuten in the disk diffusion test were determined for 275 recent bacterial isolates, including 11 species with 25 strains each. Regression analysis was performed for two disk loads (10 microg and 30 microg).

RESULTS

Correlation of MICs and zone diameters was good, with correlation coefficients of r = - 0.97 for both tested disk loads. Evaluation of the calculated zone size criteria for all species showed no very major discrepancies or no major discrepancies. The 30-microg disks, however, produced unacceptably large inhibition zones for very susceptible strains, so that usage of 10-microg disks must be recommended when testing according to DIN standards.

CONCLUSION

Based on the MIC breakpoints recommended by the DIN (> or =8 mg/L and < or = 1 mg/L), the following interpretive breakpoints for disk diffusion susceptibility tests with 10-microg ceftibuten disks were calculated using regression line analysis: < or =19 mm for resistance and > or = 27 mm for susceptiblity. Proposed inhibition zone diameters for the reference strain Escherichia coli ATCC 25922 are between 31 and 36 mm.

The new antibiotics

It is easy to become overwhelmed by the amount of information available on the new antibiotics and difficult to keep abreast of the appropriate indications for each of them. For most patients with community-acquired infections, the first-line agent is usually not one of the newer agents, but a standard regimen, or at times, no antibiotic at all. The development of resistance is likely to parallel the extent to which these agents are prescribed. They should be used only when standard treatment fails, when compliance with treatment is a real and serious issue, or when the patient has a real allergic reaction to the standard regimen.

Clinical evaluation of ceftibuten in gonorrhea. A pilot study in Hong Kong

BACKGROUND

The escalating rates of gonococcal resistance to quinolone in Hong Kong have prompted a search for an alternative first-line antimicrobial agent for use in treating uncomplicated gonococcal urethritis. Ceftibuten is an orally active third-generation cephalosporin with potent in vitro activity against Neisseria gonorrhoeae. Its pharmacokinetic properties allow single-dose administration.

OBJECTIVE

To evaluate the efficacy, safety, and tolerability of ceftibuten in the treatment of uncomplicated gonorrhea in men.

STUDY DESIGN

Ceftibuten was evaluated in an open-label, noncomparative, multicenter study. Eligible men with uncomplicated gonococcal urethritis were treated with a single 400-mg oral dose of ceftibuten and reassessed 1 week and 3 weeks after treatment. The main outcome measures were the isolation of N. gonorrhoeae, patient-reported side effects, and other safety parameters (e.g., blood counts and renal and hepatic function tests).

RESULTS

One hundred twenty-five men were enrolled in the study. The overall cure rate was 98.2% (110 of 112 evaluable patients). Adverse events, which occurred in 4.5% of patients, were all mild, well tolerated, and of short duration. No significant changes in laboratory test results were noted. Of the 125 isolates, 4.8% were -lactamase positive. Susceptibility to ofloxacin was found to be low in 59.2% of isolates (MIC 0.1 to < 1g/mL) and 25.6% of isolates were resistant (MIC1g/mL) to ofloxacin.

CONCLUSIONS

A single 400-mg oral dose of ceftibuten is highly effective and well tolerated in the treatment of uncomplicated gonococcal urethritis in men.

Randomized comparison of once-daily ceftibuten and twice-daily clarithromycin in the treatment of acute exacerbation of chronic bronchitis

In an evaluator-blind, parallel-group, multicenter study, the efficacy and tolerability of ceftibuten 400 mg capsules once daily were compared with clarithromycin 500 mg twice daily for 7-14 days in the treatment of 309 patients with acute exacerbation of chronic bronchitis (AECB). Clinical (n = 262) and microbiological (n = 71) assessments were conducted before treatment, during days 4-6 of treatment, and at 0-6 and 7-21 days after treatment. Clinical efficacy success rates (cure/improvement) at the end of treatment (0-6 days) were 91.0% for ceftibuten and 93.0% for clarithromycin. In the intent-to-treat population, the overall clinical assessment showed a success rate of 77.6% (121/156) in the ceftibuten group and 78.4% (120/153) in the clarithromycin group (95% confidence interval, -10.8 to +9.0%). One patient in each of the ceftibuten and clarithromycin groups had a microbiological relapse and became a treatment failure. The overall success rate was 84.3% for ceftibuten and 86.7% for clarithromycin (C.I. -11.7%, +6.9). Overall eradication of the target pathogens (Haemophilus influenzae, Moraxella catarrhalis, and Streptococcus pneumoniae) was 84.8% for ceftibuten and 89.5% for clarithromycin. Eradication rates for ceftibuten at 0-6 days post treatment were 95.2% (H. influenzae), 87.5% (M. catarrhalis), and 100% (S. pneumoniae), compared with 85.7%, 100% and 100%, respectively, for clarithromycin. Significantly fewer patients in the ceftibuten group experienced treatment-related adverse events than in the clarithromycin group (5.3 vs 21.9%; p < 0.001). This difference was due to a large number of patients in the clarithromycin group reporting taste perversion (12.6%) or gastrointestinal adverse events (9.9%). Given its tolerability and efficacy profiles, and the advantage of once-daily administration, ceftibuten provides a rational alternative for the treatment of AECB.

Ceftibuten: a new expanded-spectrum oral cephalosporin

OBJECTIVE

To review the antimicrobial activity, pharmacokinetics, clinical efficacy, and tolerability of ceftibuten, a new expanded-spectrum oral cephalosporin.

DATA SOURCES

Literature was identified by a MEDLINE search (January 1983-June 1996) of the medical literature, review of English-language literature and bibliographies of these articles, and data on file.

STUDY SELECTION

Clinical efficacy data were selected from all published and unpublished trials and abstracts that mentioned ceftibuten. Additional information concerning in vitro susceptibility, safety, chemistry, and pharmacokinetic profile of ceftibuten also was reviewed.

DATA SYNTHESIS

Ceftibuten, an oral expanded-spectrum cephalosporin, has a broad spectrum of activity against many gram-negative and selected gram-positive organisms, including Streptococcus pneumoniae, Streptococcus pyogenes, Moraxella catarrhalis, and Haemophilus influenzae. Ceftibuten is stable to hydrolysis by many common beta-lactamases. Ceftibuten is rapidly and almost completely absorbed from the gastrointestinal tract and is primarily eliminated renally as unchanged drug. The elimination half-life of ceftibuten is slightly longer than 2 hours. Efficacy has been demonstrated in a number of clinical trials in adults and children with upper and lower respiratory tract infections (e.g., acute otitis media, pharyngitis, sinusitis, bronchitis) and urinary tract infections. The adverse effect profile is equal to that of comparator agents.

CONCLUSIONS

Ceftibuten is an alternative to other antimicrobial agents with convenient once-daily dosing in the treatment of upper and lower respiratory tract infections. Similar to other oral expanded-spectrum cephalosporins, ceftibuten has antimicrobial activity against common pathogens of the respiratory tract and is stable in the presence of many beta-lactamases. The clinical choice of an oral expanded-spectrum cephalosporin will be based on patient acceptance, frequency of administration, and cost.

Comparative bioavailability of ceftibuten in capsule and suspension forms

The comparative bioavailability of ceftibuten, a new third-generation cephalosporin antibiotic given orally once daily, in capsule and suspension dosage forms, was assessed in healthy male subjects. In three separate studies, subjects received either a 400-mg dose as a suspension or one laboratory-batch, 400-mg capsule; one laboratory-batch, 400-mg capsule or two laboratory-batch, 200-mg capsules; or one production-batch, 400-mg capsule or two laboratory-batch, 200-mg capsules. Plasma samples were assayed for ceftibuten using high-performance liquid chromatography, and the data were assessed using pharmacokinetic and statistical methods. Confidence intervals for the maximum plasma concentration and the area under the plasma concentration-time curve extrapolated to infinity were within 80% to 125% of guidelines, demonstrating the bioequivalence of the two treatments within each of the three studies. One 400-mg capsule (laboratory or production batch) was bioequivalent to two 200-mg capsules used in a clinical efficacy trial; the 400-mg suspension was bioequivalent to a 400-mg capsule (laboratory batch). Thus we concluded that the capsule and the suspension dosage forms were bioequivalent.

Pharmacokinetics and dose proportionality of ceftibuten in men

The pharmacokinetics and dose proportionality of ceftibuten were evaluated in healthy male volunteers receiving single oral doses of 200, 400, and 800 mg of ceftibuten. The drug was absorbed with similar times to the maximum concentration of drug in plasma for all three doses. Concentrations of ceftibuten in plasma increased with increasing dose. Analysis of variance was carried out on the dose-adjusted values for the maximum concentration of drug in plasma and the area under the plasma concentration-time curve; the results indicated that the concentrations in plasma after the 200- and 400-mg doses were dose proportional, and after the 800-mg of dose they were less than dose proportional. The elimination half-life from plasma ranged from 2.0 to 2.3 h and was independent of dose. The total excretion of unchanged ceftibuten in urine accounted for 53 to 68% of the dose, and the renal clearance was estimated to be 53 to 61 ml/min after all doses. The amount of ceftibuten-trans, the major in vitro and in vivo conversion product of ceftibuten, was low in both plasma and urine.

Multiple-dose pharmacokinetics of ceftibuten in healthy volunteers

The pharmacokinetics of ceftibuten, a new cephalosporin antibiotic, and its conversion product, ceftibutentrans, were studied in healthy male volunteers following daily oral administration of a 400-mg capsule for 7 days. Mean concentrations of ceftibuten in plasma obtained on day 5 were similar to those obtained on day 7. Analysis of variance indicated that the concentrations in plasma on days 5 and 7 were at steady state. The mean accumulation factor was 1.14 for day 5 and 1.13 for day 7. The half-life (2.4 h) was independent of the duration of drug administration, and the mean maximum concentration of drug in plasma was 18 to 19 micrograms/ml. Urinary excretion was the major elimination route for ceftibuten, by which 57 to 59% of the drug was excreted unchanged over a 24-h period. The amounts of ceftibuten-trans in plasma and urine were low.

Optimal times above MICs of ceftibuten and cefaclor in experimental intra-abdominal infections

The duration of time that serum drug levels remain above the MIC (time above the MIC) for the pathogen has been shown to be the most significant parameter determining the efficacies of beta-lactam antibiotics. In the described study, we investigated the optimal time above the MIC of ceftibuten and cefaclor using a nonneutropenic mouse model of intra-abdominal infections caused by Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, and Streptococcus pneumoniae. The abilities of the drugs to protect mice against the organisms were determined in mouse protection tests, and the doses were fractionated to produce various dosing regimens with different times above the MIC. All drug-organism combinations showed a significant correlation (r > 0.9) between drug efficacy and the time above the MIC. Also, with ceftibuten treatment, the different dosing regimens that produced equal times above the MIC resulted in the same efficacy, whereas with cefaclor, an apparent dose-dependent effect was observed. These results showed that for a 100% recovery from K. pneumoniae and E. coli infections, the optimal times above the MIC with ceftibuten treatment were 2.2 and 1.6 h, respectively. Relatively high doses of both antibiotics were required to ensure recovery from S. pneumoniae infections. In vitro time-kill studies demonstrated that cefaclor exhibits a marked inoculum effect against the pathogens, and there was a concentration-dependent killing at a large inoculum size. On the other hand, ceftibuten showed no inoculum effect. It is suggested that optimization of both dose and time above the MIC appears to be necessary for the treatment of S. aureus infections with cefaclor, and this may apply to other beta-lactams tht exhibit marked inoculum effects.

Susceptibilities of beta-lactamase-producing and -nonproducing ampicillin-resistant strains of Haemophilus influenzae to ceftibuten, cefaclor, cefuroxime, cefixime, cefotaxime, and amoxicillin-clavulanic acid

In in vitro studies we evaluated the susceptibilities of beta-lactamase-producing and -nonproducing, ampicillin-resistant strains of Haemophilus influenzae and compared them with those of ampicillin-susceptible strains. Ampicillin, amoxicillin-clavulanic acid, ceftibuten, cefaclor, cefuroxime, cefixime, and cefotaxime were evaluated by broth microdilution tests and disk diffusion tests. The disk diffusion tests accurately categorized beta-lactamase-producing strains and ampicillin-susceptible strains as being susceptible to the study drugs other than ampicillin. Ampicillin-resistant, beta-lactamase-nonproducing strains were relatively resistant to all seven study drugs, but the disk diffusion test did not always predict that resistance. The clinical relevance of the decreased susceptibility to various agents remains unclear, but to be conservative, all ampicillin-resistant, beta-lactamase-nonproducing strains might be assumed to be resistant to other beta-lactams. After excluding that small group of isolates, reliable susceptibility test results were obtained with lots of Haemophilus Test Medium that met quality assurance criteria.

The efficacy and safety of once-daily ceftibuten compared with co-amoxiclav in the treatment of acute bacterial sinusitis

The efficacy and safety of a once-daily oral regimen of 400 mg ceftibuten was compared with oral co-amoxiclav 500 mg three times daily in a multicentre, single-blind study. In patients with a bacteriologically confirmed infection, a successful clinical outcome was reported in 25 of 25 patients treated with ceftibuten and 10 of 10 patients treated with co-amoxiclav. In a further group of 88 patients, most of whom had been excluded from the primary efficacy evaluation because no pathogen was isolated pretreatment, overall successful clinical outcomes of 87% and 88% were reported for ceftibuten and co-amoxiclav, respectively. The duration of treatment and the time to resolution of the signs and symptoms of sinusitis were not significantly different in the two treatment groups. The incidence of adverse events was higher in the co-amoxiclav-treated patients (31% versus 15% in the ceftibuten group) as was the incidence of severe events (10% for co-amoxiclav-treated patients versus < 1% in the ceftibuten group). In summary, once-daily ceftibuten can be considered a safe and effective treatment for acute bacterial sinusitis.

Pharmacokinetics of ceftibuten-cis and its trans metabolite in healthy volunteers and in patients with chronic renal insufficiency

The impact of renal insufficiency on the dispositions of 300 mg of orally administered ceftibuten-cis, a new broad-spectrum oral cephalosporin, and its primary metabolite ceftibuten-trans was characterized in 30 adult subjects. Subjects were divided into five groups of six subjects each on the basis of their 24-h ambulatory creatinine clearances (CLCR). The apparent total body clearance (CLP/F; where F is absolute bioavailability) and renal clearance of ceftibuten-cis were significantly lower in subjects with end-stage renal disease (on maintenance hemodialysis; group V) and in those with severe (CLCR, 5 to 29 ml/min; group IV) and moderate (CLCR, 30 to 49 ml/min; group III) renal insufficiency than in those with mild renal insufficiency (CLCR, 50 to 80 ml/min; group II) or normal renal function (CLCR, greater than 80 ml/min; group I). A significant correlation was observed between CLCR and ceftibuten-cis CLP/F. The mean apparent steady-state volume of distribution (V beta/F) of ceftibuten-cis ranged from 0.21 to 0.24 liter/kg in subjects in group I, II, III, and IV. V beta/F was significantly greater in the group V subjects with end-stage renal disease (V beta/F, 0.39 +/- 0.27 liters/kg). These changes in V beta/F cannot be separated from possible changes in bioavailability. The maximum concentration of ceftibuten-trans in plasma was significantly higher and occurred significantly later in group IV subjects than it did in subjects in the other groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibacterial activity of ceftibuten, a new oral third generation cephalosporin

Ceftibuten, a new oral third generation cephalosporin, was found to be the most active beta-lactam drug tested against members of the Enterobacteriaceae, inhibiting most strains at less than 4 micrograms/ml. All isolates of Branhamella catarrhalis, Haemophilus influenzae, and Neisseria spp. were highly susceptible to ceftibuten. Penicillin-sensitive pneumococci and pathogenic beta-hemolitic streptococci were also killed by ceftibuten. The antibacterial activity of this new drug, which results in rapid lysis of susceptible cells, was not significantly affected by serum, pH, inoculum size, media composition and growth conditions. Ceftibuten is characterized by a remarkable resistance to inactivation by most beta-lactamases synthetized by common gram-positive and gram-negative pathogens. The potent in vitro activity of ceftibuten in conjunction with its favorable pharmacokinetic profile render this new molecule an attractive candidate for the treatment of respiratory and urinary tract infections sustained by susceptible pathogens.

Treatment of acute uncomplicated urinary tract infection with ceftibuten

Ceftibuten is an orally active third generation cephalosporin with increased potency against members of the Enterobacteriaceae. In this study, 74 women with acute uncomplicated urinary tract infection (UTI) were enrolled in an open study to evaluate the safety and efficacy of this new antibiotic. Patients were treated with 400 mg ceftibuten once daily for seven days and followed for four to six weeks after cessation of therapy. All pathogens were eradicated during treatment, including five coagulase-negative staphylococci that were resistant to ceftibuten. At five to nine days posttreatment, 93% of patients were cured. Of the five recurrent infections, four patients had a relapse and one had a reinfection. By four to six weeks posttreatment, five additional patients had recurrent infections. The overall cure rate was 85% in this study. Most ceftibuten-associated adverse effects were mild and involved the gastrointestinal tract. Diarrhea was the most commonly reported side effect. Of the eight (11%) patients who developed diarrhea, three had a positive latex agglutination test for Clostridium difficile. The diarrhea resolved in all patients without sequelae. Ceftibuten was effective and generally safe in the treatment of women with acute uncomplicated UTI. The high incidence of diarrhea observed in this study is a concern.

Antimicrobial activity and spectrum of ceftibuten (7432-S, SCH 39720)--a review of United States and Canadian results

Preliminary in vitro studies of ceftibuten in the United States and Canada have demonstrated a potent activity against enteric bacilli (greater than 90% of routine clinical isolates), Haemophilus influenzae, Moraxella catarrhalis, Neisseria spp., most B-hemolytic streptocci, and Streptococcus pneumoniae. Ceftibuten was demonstrated to be bactericidal, minimally influenced by high inocula, beta-lactamase stable, an inhibitor of type Ia beta-lactamase, and potentially usable against some Enterobacteriaceae strains capable of destroying other newer cephalosporins (ceftazidime and cefixime). In vitro test methods have been standardized, and preliminary quality control guidelines have been proposed for clinical trials. The ceftibuten spectrum seems best suited for therapy of urinary tract, respiratory, and genital tract infections as an alternative to older oral cephalosporins, recently marketed esters (cefuroxime axetil), and cefixime.

Ability of ceftibuten to induce the class-I beta-lactamases of Enterobacter cloacae, Serratia marcescens, and Enterobacter aerogenes

Ceftibuten, like cefotaxime, was observed to be a weak inducer of the class-I beta-lactamases of Enterobacter cloacae, Serratia marcescens, and Enterobacter aerogenes. In contrast, cefoxitin and imipenem induced these enzymes strongly at subinhibitory concentrations.

Ceftibuten: a new orally absorbed cephalosporin. In vitro activity against strains from the United Kingdom

The in vitro activity of ceftibuten was studied in 572 bacterial strains and was compared with the activity of other orally administered beta-lactams. Ceftibuten displayed high activity against the Enterobacteriaceae, generally being 16-fold more active than cefuroxime, cefaclor, cephalexin, or amoxicillin-clavulanic acid. Its activity was comparable to cefixime. There was little ceftibuten or cefixime activity against staphylococci (MIC90s greater than or equal to 64 micrograms/ml) and reduced activity against Streptococcus pneumoniae (MIC90, 16 micrograms/ml). Haemophilus influenzae and Neisseria spp. were highly susceptible to ceftibuten and cefixime. The protein binding of ceftibuten was 77%, and the primary target site was PBP 3. A high degree of stability to beta-lactamase hydrolysis was observed.

The pharmacokinetics of ceftibuten in humans

The pharmacokinetics of ceftibuten, a new oral cephalosporin, has been studied in humans. Ceftibuten is very well absorbed in young and old patients. Absorption may be slightly decreased by food or relatively high doses (800 mg). The pharmacokinetics have been well characterized in rising single-dose and multiple-dose studies. The half-life is relatively long for this class of drugs, being approximately 2-3 hr. Apparent plasma clearance (CL/F), is approximately 40-75 ml/min, and the renal clearance is approximately 30-50 ml/min, corresponding to the fraction excreted unchanged in the urine of approximately 60%-70% of the dose. The apparent volume of distribution after oral dosing (Vd/F) was approximately 0.2 L/kg. The half-life, plasma clearance, renal clearance, and fraction excreted in urine are not affected by increasing dose and are constant during multiple dosing. There is little drug accumulation during multiple dosing. Drug elimination is decreased in patients with renal insufficiency and dosing in these patients should be adjusted relative to creatinine clearance values. The drug penetrates very well to experimentally induced inflammatory fluid but produces negligible levels in breast milk. The drug has no effect on the pharmacokinetics of theophylline. The drug is well tolerated and has pharmacokinetic properties that are clinically advantageous.

Ceftibuten and bactericidal kinetics. Comparative in vitro activity against Enterobacteriaceae producing extended spectrum beta-lactamases

Ceftibuten, compared to cefixime, cefetamet, cefpodoxime, loracarbef, cefprozil, cefuroxime, cefaclor, and cefadroxil, was the most active oral cephalosporin derivative against Enterobacteriaceae producing plasmid-encoded broad spectrum beta-lactamases. In a pharmacodynamic model, ceftibuten was bactericidal for Haemophilus influenzae and Streptococcus pneumoniae at concentrations simulating human serum levels following 200 mg, p.o., b.i.d.

Comparative antimicrobial activity of ceftibuten against multiply-resistant microorganisms from Belgium

To study the activity of ceftibuten, we obtained multiply-resistant isolates from approximately 20 hospitals in Belgium. Against Enterobacteriaceae, all of the tested comparative compounds were more active than cefaclor, and ceftibuten and tigemonam were the most active of the agents tested. Ceftibuten MIC50s were less than or equal to 1 microgram/ml for most enteric bacilli species and 85% of strains were susceptible (less than or equal to 8 micrograms/ml). This level of activity compared favorably to that recorded for cefaclor (less than or equal to 8 micrograms/ml), cefetamet (less than or equal to 4 micrograms/ml), and cefteram (less than or equal to 1 microgram/ml), that is, 37%, 69%, and 59%, respectively. Ceftibuten, cefetamet, cefteram, and tigemonam were highly active against isolates of Haemophilus influenzae and Neisseria gonorrhoeae. None of the comparative agents were as active as cefaclor against staphylococcal isolates. Against streptococci, cefteram was the most active, and tigemonam the least active of the agents. The MIC90s of ceftibuten for strains of Streptococcus pneumoniae and Streptococcus pyogenes were 2 micrograms/ml and 0.5 microgram/ml, respectively. Strains of Streptococcus agalactiae were resistant to both ceftibuten and tigemonam; cefaclor and cefteram inhibited 100% of isolates of this species. Strains of Enterococcus faecalis and Pseudomonas aeruginosa were consistently resistant to all of the compounds. Overall, ceftibuten exhibited potent activity against many multiply-resistant clinical isolates.

Comparative antimicrobial spectrum and activity of ceftibuten against clinical isolates from West Germany

The in vitro activity of a new oral cephalosporin, ceftibuten, was determined against 837 clinical isolates by agar dilution technique and compared with that of the oral cephalosporins, cefaclor, cefuroxime, cefixime, cefpodoxime, and cefprozil. Against Enterobacteriaceae, ceftibuten was the most active of the compounds. Ceftibuten MIC90s were less than or equal to 0.25 micrograms/ml for most members of the family Enterobacteriaceae, 0.13 microgram/ml for Haemophilus influenzae, 4 micrograms/ml for Moraxella catarrhalis, and 0.5 microgram/ml for Neisseria gonorrhoeae. Ceftibuten also was active against beta-haemolytic streptococci (serogroups A, C, and G) and penicillin-susceptible strains of Streptococcus pneumoniae (MIC90, 4 micrograms/ml), but was not active against Staphylococcus spp. or the anaerobic bacteria studied. Cefpodoxime and cefuroxime were the most active of the cephalosporins against nonenteric streptococci; cefprozil and cefuroxime were the most active against staphylococci, and cefaclor demonstrated the greatest activity against some Bacteroides spp. Most strains of Acinetobacter baumanii, Pseudomonas spp., and methicillin-resistant staphylococci, as well as all strains of Clostridium difficile, were resistant to each of the cephalosporins tested.

Randomized comparative study of ceftibuten versus cefaclor in the treatment of acute lower respiratory tract infections

In a randomized, single-blind trial, ceftibuten in doses of 200 mg and 300 mg administered b.i.d., was compared with cefaclor 500 mg t.i.d. in acute lower respiratory tract infections. A total 545 patients were enrolled, of which 263 were evaluable for efficacy. All patients were adults with a diagnosis of either bacterial pneumonia or bronchitis. The infective organism was eliminated in 83% of the patients in the ceftibuten 200-mg b.i.d. treatment group and in 85% of patients in the 300-mg b.i.d. treatment group. The organisms were eliminated in 79% of cefaclor-treated patients. Satisfactory clinical responses were obtained in 91% of patients in the ceftibuten 200-mg b.i.d. treatment group and in 92% of patients in the ceftibuten 300-mg b.i.d. group. Satisfactory clinical responses were obtained in 91% of cefaclor-treated patients. Predominant pathogens isolated were Streptococcus pneumoniae, Haemophilus influenzae, Moraxella (Branhamella) catarrhalis, and strains of Enterobacteriaceae. Adverse experiences reported were similar for the ceftibuten and cefaclor treatment groups. Gastrointestinal side effects occurred in 6% of patients treated with ceftibuten 200 mg BID, 9% in those treated with 300 mg BID, and 7% of cefaclor-treated patients. Ceftibuten 200 and 300 mg twice daily was as effective as cefaclor bacteriologically and clinically in the treatment of lower respiratory tract infections.

Interpretive criteria and quality control limits for ceftibuten disk susceptibility tests. Collaborative Antimicrobial Susceptibility Testing Group

In vitro studies were undertaken to evaluate susceptibility tests with 30-micrograms ceftibuten disks. The following interpretive criteria were proposed: less than or equal to 17 mm for resistance (MIC, greater than or equal to 32 micrograms/ml) and greater than or equal to 21 mm for susceptibility (MIC, less than or equal to 8.0 micrograms/ml). A multilaboratory quality control study led to the conclusion that Escherichia coli ATCC 25922 should provide zones 29 to 35 mm in diameter.

Comparative in vitro activity and beta-lactamase stability of FK482, a new oral cephalosporin

FK482 is an oral aminothiazolyl hydroxyimino cephalosporin with a C-3 vinyl group. Its activity was compared with those of cephalexin, cefuroxime, cefixime, and amoxicillin-clavulanate. FK482 inhibited 90% of Staphylococcus aureus isolates at 1 micrograms/ml and 90% of Streptococcus pyogenes, Streptococcus agalactiae, and Streptococcus pneumoniae isolates at less than or equal to 0.012 micrograms/ml, superior to cephalexin and cefuroxime and similar to cefixime. It did not inhibit oxacillin-resistant S. aureus. FK482 inhibited 90% of Enterococcus faecalis isolates at 8 micrograms/ml. Although 90% of Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Salmonella species, and Shigella species isolates were inhibited by less than or equal to 2 micrograms/ml, FK482 was less active than cefixime against Citrobacter, Enterobacter, Morganella, Serratia, and Providencia species, with MICs for many isolates of greater than 8 micrograms/ml. FK482 inhibited Haemophilus influenzae and Neisseria gonorrhoeae at concentrations comparable to that of cefixime and superior to those of cephalexin and cfaclor. Bacteroides and Pseudomonas species were resistant. FK482 was not hydrolyzed by the TEM-1 and TEM-2 beta-lactamases but was hydrolyzed by TEM-3 and the Proteus vulgaris enzyme. It had a high affinity for chromosomal beta-lactamases.