In vitro activity of an oral iminomethoxy aminothiazolyl cephalosporin, R-3746

An update on community-acquired pneumonia in adults

Community-acquired pneumonia (CAP) is a leading cause of morbidity and mortality, despite effective therapies. Guidelines for CAP management vary widely in their approach. Resistance of S pneumoniae to penicillins and other antibiotics has prompted evaluation of the new fluoroquinolones.

Cefaclor: a contemporary look at susceptibility of key pathogens from around the globe

The orally administered cephalosporin antibiotic, cefaclor, has been available for clinical use in many countries since 1979. Because widespread antibiotic use is often cited as a factor in the emergence of bacterial resistance to antibiotics, we sought to determine the degrees of resistance to cefaclor expressed by key pathogens recently isolated in 10 countries widely distributed around the world. Using the E-test, minimal inhibitory concentrations (MIC) were determined for cefaclor and several comparator antibiotics against approximately 700 fresh clinical isolates of each of six bacterial species. The results demonstrated that > 90% of Haemophilus influenzae (beta-lactamase producing and non-producing), Haemophilus parainfluenzae (beta-lactamase producing and non-producing), Moraxella catarrhalis (> 90% beta-lactamase producing), and methicillin-susceptible Staphylococcus aureus, and 85% of Escherichia coli were susceptible to cefaclor at the NCCLS interpretive breakpoints. MIC distributions showed that there has been no change in the activity of cefaclor against penicillin-susceptible strains of Streptococcus pneumoniae since 1977.

Penetration of cefpodoxime into uterine and vaginal secretions from postpartum women after a single oral dose of cefpodoxime proxetil

We evaluated the usefulness of cefpodoxime proxetil (CPDX-PR) in the treatment of puerperal infection and obtained the following results. (i) The susceptibilities of 124 clinical isolates from 85 uterine lochia samples were determined. The MIC at which the growth of Streptococcus agalactiae, Escherichia coli, and Bacteroides fragilis isolates was inhibited by 90% (MIC90) was 0.39 micrograms/ml or less. The MIC90 for Staphylococcus aureus was 3.13 micrograms/ml. (ii) Seven puerperal women received 200 mg of CPDX-PR orally. The CPDX concentration in the lochias in the uterine cavity was not statistically different from that in the vagina, suggesting that the vaginal samples, which can be obtained more safely and aseptically, can be substituted for the uterine samples. The CPDX concentration in cubital venous blood reached a peak of 1.61 micrograms/ml at 3 hours after CPDX-PR administration. The CPDX concentration in the lochias gradually increased and reached a peak of 1.20 micrograms/ml in the uterine cavity and 1.27 micrograms/ml in the vagina at 5 h after drug administration and gradually declined thereafter. These results suggest that CPDX-PR, with its good transfer to the lochia and its potent antimicrobial activity, is a promising drug for the prophylactic and therapeutic treatment of puerperal infections caused by susceptible organisms.

The role of cefotaxime in the treatment of surgical infections

This study examines the role of cefotaxime in the treatment of both Gram-negative and Gram-positive surgical infections. A dose of 2 g of cefotaxime will sustain peripheral compartment concentrations of 2.6, 3.9, 1.6, and 0.7 micrograms/ml for 6, 8, 10 and 12 h, respectively. Therefore, the proportion of pathogens with a minimal inhibitory concentration (MIC) below the peripheral compartment cefotaxime concentrations was assessed as a measure of therapeutic potential. It was observed that bacterial elimination in infections correlates well with such pharmacodynamic predictions. Therefore, treatment recommendations for surgical infections are based on the following pharmacodynamics. The times above the MIC in the tissue compartment for various pathogens (1988-1994) known to cause surgical infections were: Escherichia coli, 12 h; all pyogenic streptococci, 12 h; pneumococci, 12 h; Haemophilus spp., 12 h; Proteus mirabilis, 12 h; Klebsiella spp., 10.9 h; viridans streptococci, 10.6 h; oxacillin-susceptible, coagulase-negative staphylococci, 9.7 h; Providencia spp., 9.2 h; Clostridium perfringens, 8.6 h; Peptostreptococcus spp., 8 h; oxacillin-susceptible Staphylococcus aureus, 7.3 h; and all S. aureus, 6.8 h. From the examination of pharmacodynamic parameters, cefotaxime appears to be a viable choice for the therapy of surgical infections other than the Gram-negative anaerobes. For those infections, metronidazole with cefotaxime would be preferred.

In vitro activity of cefpodoxime in comparison with other oral beta-lactam antibiotics

The aim of our study was to re-evaluate the in vitro activity of cefpodoxime in comparison with other oral beta-lactam antibiotics against bacteria causing respiratory tract infections. The study drugs were cefpodoxime, cefaclor, cefixime, cefuroxime, cefetamet, cefprozil, and the combination of amoxicillin and clavulanic acid (= augmentin). In addition, cefotaxime as the standard agent of parenteral third generation cephalosporins was examined. The organisms tested were Staphylococcus aureus, Streptococcus pyogenes, Streptococcus agalactiae, streptococci of serogroups C and G, Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae and Proteus mirabilis. Minimal inhibitory concentrations of the antimicrobials were determined with the agar dilution procedure. Cefpodoxime showed the broadest spectrum and generally also the highest activity of the oral beta-lactam antibiotics examined. The drug was equally active against the major groups of beta-lactamase negative and positive bacteria causing respiratory tract infections. Against penicillin-resistant pneumococci, all beta-lactam agents exhibited reduced activity comparable to the reduced activity of penicillin.

Twice daily cefpodoxime proxetil compared with thrice daily amoxicillin/clavulanic acid for treatment of acute otitis media in children

A total of 260 children, 3 months to 11 years old (median age 24 months), with acute otitis media (AOM) received either cefpodoxime proxetil (CP) 8 mg/kg/d b.i.d. or amoxicillin/clavulanic acid (ACA) 40/10 mg/kg/d t.i.d. for 8 days. A significant difference in clinical cure rates was observed between the CP group 71/118 (60%) and the ACA group 42/105 (40%), p = 0.003. At the follow-up visit (20-30 days after the start of treatment), significant advantages were recorded with the CP vs. ACA therapy, in terms of satisfactory clinical response [90/111 (81%) vs 60/94 (63.8%), p = 0.005] residual middle ear effusion (14.4% vs 28.7%, p = 0.01) and normal tympanometry (78% vs 61.4%, p = 0.017). Compliance and adverse event frequency were the same in both treatment groups. The higher clinical cure rate and equivalent safety profile of CP indicates that it is an acceptable alternative to ACA for the treatment of AOM in children.

Five versus ten days treatment of streptococcal pharyngotonsillitis: a randomized controlled trial comparing cefpodoxime proxetil and phenoxymethyl penicillin

A total of 220 adults and children > 10 years old (mean 29.5 +/- 11.7 years) with pharyngitis/tonsillitis were randomized to receive either cefpodoxime proxetil 100 mg bid for 5 days (n = 113) or phenoxymethyl penicillin, 600 mg tid for 10 days (n = 107). At the end of treatment of the 166 evaluable patients, a satisfactory clinical response was obtained in 85/88 (96.6%) patients treated with cefpodoxime proxetil and in 75/78 (96.1%) treated with phenoxymethyl penicillin. Group A beta-hemolytic streptococci (GABHS) eradication was similar in both groups: 79/82 (96.3%) patients in the cefpodoxime proxetil group and 64/68 (94.1%) patients in the phenoxymethyl penicillin group. At follow-up (20-30 days after the end of treatment) the GABHS eradication persisted in 67/72 (93.1%) patients treated with cefpodoxime proxetil and in 56/61 (91.8%) patients treated with phenoxymethyl penicillin. Significantly better compliance (p < 0.01) was noticed with the cefpodoxime proxetil regimen compared with the phenoxymethyl penicillin regimen, with only 2/110 (2%) poorly compliant patients in the cefpodoxime proxetil group vs 17/104 (16%) in the phenoxymethyl penicillin group. Thus, the shorter duration of therapy, in conjunction with demonstrated clinical and bacteriological efficacy that is equivalent to standard therapy, makes cefpodoxime proxetil an acceptable alternative for the treatment of GABHS pharyngitis/tonsillitis.

Prediction of bacterial susceptibility to cefpodoxime by using the ceftriaxone minimum inhibitory concentration result

The cross-resistance or cross-susceptibility of cefpodoxime and ceftriaxone for 3700 strains of Enterobacteriaceae, oxacillin-susceptible staphylococci, Streptococcus spp., Haemophilus influenzae, Moraxella catarrhalis, and Neisseria gonorrhoeae was evaluated. With the exception of tests with Enterobacter spp. and Morganella morganii, the ceftriaxone minimum inhibitory concentration (MIC) result interpretive criteria predicted bacterial susceptibility (or resistance) to cefpodoxime with an acceptable rate of serious interpretive errors (1.5%) and an absolute categorical agreement > 92%. By using cefpodoxime interpretive criteria for ceftriaxone MICs, the interpretive errors for testing enteric bacilli were reduced from 2.1% to 1.5%.

Cefpodoxime proxetil. A review of its antibacterial activity, pharmacokinetic properties and therapeutic potential

Cefpodoxime proxetil is an orally administered prodrug which is absorbed and de-esterified by the intestinal mucosa to release the third generation cephalosporin, cefpodoxime. Cefpodoxime is stable towards the most commonly found plasmid-mediated beta-lactamases and the drug has a broad spectrum of antibacterial activity encompassing both Gram-negative and Gram-positive bacteria, rendering it a possible option for empirical use in a wide range of community acquired infections in both adult and paediatric patients. The extended plasma half-life of cefpodoxime (1.9 to 3.7 h) permits twice daily administration. In comparative trials, twice daily cefpodoxime proxetil (dose equivalent cefpodoxime 100 to 400 mg) was as effective as a 3- to 4-times daily regimen of phenoxymethylpenicillin in pharyngotonsillitis, as well as thrice daily amoxicillin (with or without clavulanic acid) or cefaclor against infections of the ear, the upper and lower respiratory tract, the urinary tract and those of the skin and soft tissues. The latter reflects the enhanced antistaphylococcal activity of cefpodoxime, which distinguishes it from other orally active third generation cephalosporins such as cefixime. Most notably, an oral regimen of cefpodoxime proxetil was as efficacious as parenterally administered ceftriaxone for the treatment of bronchopneumonia in hospitalised patients at risk due to the presence of underlying diseases, addictions or advancing age. A single oral dose of cefpodoxime was also as efficacious as ceftriaxone in uncomplicated anogenital gonococcal infections. Cefpodoxime proxetil is generally well tolerated, with mild to moderate gastrointestinal disturbances occurring in 4 to 15% of patients treated with therapeutic doses. Thus, a convenient twice daily oral regimen of cefpodoxime proxetil can be prescribed as an effective alternative to established beta-lactam therapies in the empirical outpatient treatment of infections of the respiratory and urinary tracts as well as those of the skin and soft tissues.

Cefpodoxime proxetil compared with amoxicillin-clavulanate for the treatment of otitis media

In a multicenter, randomized, investigator-blinded trial, patients were randomly selected to receive either cefpodoxime proxetil or amoxicillin-clavulanate potassium orally for the treatment of acute suppurative otitis media. Patients were seen before, during, and at the end of therapy, and 2 to 3 weeks after completion of therapy. A total of 229 patients, 153 receiving cefpodoxime and 76 receiving amoxicillin-clavulanate were entered into the study; all patients were examined to determine drug safety. A total of 146 patients, 98 in the cefpodoxime group and 48 in the amoxicillin-clavulanate group, completed the study and were examined to determine drug efficacy. End-of-therapy microbiologic eradication rates in assessable patients were 92% for cefpodoxime and 86% for amoxicillin-clavulanate (p = 0.14; 95% confidence interval (CI) on difference: -4.4%, 19.2%). End-of-therapy clinical response rates for assessable patients were as follows: cured, 68% for cefpodoxime and 65% for amoxicillin-clavulanate; improved, 24% for cefpodoxime and 23% for amoxicillin-clavulanate; and failed, 8% for cefpodoxime and 13% for amoxicillin-clavulanate (p = 0.57; 95% CI: -8.4%, 16.5%). Recurrence rates at long-term follow-up were 24% for cefpodoxime-treated patients and 25% for those given amoxicillin-clavulanate. Both drugs were well tolerated; 20.9% of those given cefpodoxime and 31.6% of amoxicillin-clavulanate-treated patients had drug-related adverse medical events (p = 0.102; 95% CI: -23.9%, 2.6%). Gastrointestinal complaints were the most frequently reported drug-related side effect in both groups: 11.8% of cefpodoxime-treated patients and 21.1% of those given amoxicillin-clavulanate (p = 0.076; 95% CI: -20.8%, 2.2%). Drug-related dermatologic side effects (e.g., diaper rash, pruritus, urticaria) were reported in 7.8% of cefpodoxime-treated patients and 14.5% of those who received amoxicillin-clavulanate (p = 0.160; 95% CI: -16.6%, 3.3%). Our findings suggest that clinical efficacy for cefpodoxime administered twice daily is equivalent to that of amoxicillin-clavulanate administered three times a day.

In vitro activity and susceptibility to hydrolysis of S-1006

The in vitro activity of S-1006, the active component of a new orally absorbed cephalosporin, S-1108, inhibited 90% of Staphylococcus aureus isolates at less than or equal to 2 micrograms/ml, 90% of group A, B, C, F, and G streptococci and Streptococcus pneumoniae isolates at less than or equal to 0.12 microgram/ml, and all Haemophilus influenzae isolates at less than or equal to 0.06 microgram/ml. Although 50% of the members of the family Enterobacteriaceae were inhibited by less than or equal to 2 micrograms of S-1006 per ml, Enterobacter spp. and Citrobacter freundii resistant to ceftriaxone were resistant to S-1006. The MICs of S-1006 for approximately 20% of Providencia, Proteus vulgaris, and Serratia isolates were 4 micrograms/ml. S-1006 was hydrolyzed by the plasmid TEM-3, TEM-5, PSE-1, and PSE-4 beta-lactamases and by the chromosomal beta-lactamase of Enterobacter and Morganella spp. and P. vulgaris.

Pharmacokinetics of cefpodoxime proxetil and interactions with an antacid and an H2 receptor antagonist

Cefpodoxime proxetil is a new oral esterified cephem antibiotic with a broad antibacterial spectrum. The dissolution of cefpodoxime proxetil is pH dependent. The objectives of this study were to characterize the pharmacokinetics of cefpodoxime proxetil in two different oral doses and to examine possible interactions with an antacid, aluminum magnesium hydroxide (Maalox 70), and an H2 receptor antagonist, famotidine. Two studies involving the same 10 healthy volunteers were performed. In the first study, cefpodoxime proxetil was administered in two doses, 0.1 and 0.2 g. In the second study, two interventions were performed in a randomized crossover design. For one intervention, the volunteers were pretreated with 40 mg of famotidine 1 h before 0.2 g of cefpodoxime proxetil was administered. In the second trial, participants were given 10 ml of Maalox 70 2 h and 10 ml of Maalox 70 15 min before they received 0.2 g of cefpodoxime proxetil. Serum and urine concentrations were determined by high-performance liquid chromatography. For the statistical evaluation, these data were tested by using the pharmacokinetics of 0.2 g of cefpodoxime proxetil from the first study. The maximum concentrations were 1.19 +/- 0.32 mg/liter after 0.1 g of cefpodoxime proxetil and 2.54 +/- 0.64 mg/liter after 0.2 g of cefpodoxime proxetil. The elimination half-lives were 149 min for 0.1 g and 172 min for 0.2 g of cefpodoxime proxetil. The total increase in the area under the concentration-time curve (AUC) was dose dependent. Combination with Maalox 70 caused a reduction in the AUC from 14.0 +/- 3.9 to 8.44 +/- 1.85 mg.h/liter. After famotidine, the AUC decreased to 8.36 +/- 2.0 mg . h/liter. Corresponding changes were registered for the maximum concentration of drug in serum, 24-h urine recovery, and the time to maximum concentration of drug serum. Cefpodoxime proxetil was well tolerated without any seriously adverse drug reactions.

In vitro activity and cross resistance studies with cefpodoxime

On the basis of MIC determinations and appropriate MIC breakpoints, 370 pathogens showed complete cross resistance between cefpodoxime and cefuroxime axetil, cefotiam hexetil, cefixime and cefotaxime in 69.7%, 80.3%, 92.2% and 87% of the strains, respectively. Cefpodoxime was superior to cefuroxime axetil in 28.7%, to cefotiam hexetil in 17.6%, to cefixime in 7% of strains and to cefotaxime not at all. On the other hand, we found cefpodoxime to be inferior to the cephalosporins mentioned in 1.6%, 2.1%, 0.8% and 13%, respectively.

Cefpodoxime: comparative antibacterial activity, influence of growth conditions, and bactericidal activity

The antimicrobial activity of cefpodoxime, the active metabolite of the new cephalosporin ester cefpodoxime proxetil, in comparison to cefixime, cefotiam, cefuroxime, and cefotaxime was determined against a broad spectrum of freshly isolated gram-positive and gram-negative bacterial strains. Cefpodoxime was demonstrated to be inhibitory at concentrations of less than or equal to 1 mg/l against 90% of strains of Moraxella catarrhalis, Haemophilus influenzae, Escherichia coli (beta-lactamase- negative strains), Klebsiella spp., Serratia spp., Proteus mirabilis, Proteus vulgaris, Providencia spp., and Salmonella spp. This antimicrobial activity of cefpodoxime was generally superior to that of cefuroxime and similar to that of cefixime. Cefpodoxime was active at less than or equal to 1 mg/l against 50% of the members of beta-lactamase-producing Escherichia coli, Enterobacter cloacae, Enterobacter aerogenes, Citrobacter spp., and Morganella morganii. Cefpodoxime proved to be highly inhibitory against group A, B, and G streptococci and Streptococcus pneumoniae (MIC90 less than 0.015 mg/l). The MICs of cefpodoxime and those of the other cephalosporins were less than 2 mg/l for greater than or equal to 90% of the strains of Staphylococcus aureus and Staphylococcus epidermidis, with the exception of cefixime which had no activity with MICs below 8 mg/l against these bacteria. Pseudomonas spp., Acinetobacter spp., and Enterococcus spp. were resistant to cefpodoxime. The antibacterial activity of cefpodoxime was only to a minor degree influenced by different growth conditions with the exception of high inoculum sizes against some beta-lactamase producing strains of gram-negative bacilli.(ABSTRACT TRUNCATED AT 250 WORDS)

In vitro activity of cefpodoxime, a new oral cephalosporin, compared with that of nine other antimicrobial agents

The in vitro activity of the compound RU-51746, the sodium salt of cefpodoxime (which is administered orally as the ester cefpodoxime proxetil) was compared with that of other commonly used oral antibiotics against a selection of clinical isolates of common bacteria from patients with urinary tract, soft tissue and respiratory tract infections. RU-51746 was found to inhibit 90% of Enterobacteriaceae at less than 1 mg/l; pneumococci, pyogenic streptococci (Lancefield groups A, C and G) and Streptococcus agalactiae were almost all inhibited by concentrations of less than 0.06 mg/l; Haemophilus influenzae (including beta-lactamase producers) were inhibited by less than 1 mg/l; 90% of Branhamella catarrhalis were inhibited at less than 2 mg/l. Activity against Acinetobacter spp. and staphylococci was variable and enterococci were all resistant.

Influence of cefpodoxime on selected immunological functions and bacterial pathogenicity factors in vitro

The influence of a new oral cephalosporin cefpodoxime, on several interactions of the host-parasite relationship was investigated. Pretreatment of polymorphonuclear granulocytes (PNG) with cefpodoxime at therapeutical dosage in vitro did not have a significant effect on chemotaxis and luminol-dependent chemiluminescence. On the other hand, human serum did not exert a considerable effect on the bactericidal activity of cefpodoxime on Klebsiella pneumoniae and Staph. aureus. Serum resistance of Klebsiella pneumoniae was not altered after pretreatment with cefpodoxime 1/16 MIC (0.03 micrograms/ml) for 3 to 27 hours.

Cefpodoxime proxetil concentrations in head and neck tissues

Three to six hours prior to surgery in the head and neck a single dose of 200 mg cefpodoxime proxetil was administered orally to 30 patients. During surgery serum and tissue samples (concha, mocosa, cartilage, bone, parotis and tonsil) were taken and the concentrations of cefpodoxime were determined by bioassay. The serum concentrations ranged from 0.72 mg/l (determined after 6 h 22 min) to 3.34 mg/l (3 h 15 min). The tissue concentrations were between 0.15 mg/l (determined in bone after 5 h 18 min) and 1.94 mg/l (concha 4 h 13 min). Analogously to recent in vitro data the concentrations reached in head and neck tissue were higher than the MIC90 values for most pathogens of upper respiratory tract infections.

Microbiological evaluation of cefpodoxime proxetil

Cefpodoxime, the active de-esterified molecule of the orally absorbable cephalosporin cefpodoxime proxetil, inhibits streptococci, Neisseria spp., and most Enterobacteriaceae, with MIC50 and/or MIC90 values of less than or equal to 2 mg/L; with regard to the latter family of bacteria, the MIC50 and/or MIC90 values of cefpodoxime are consistently greater than or equal to 4 mg/L for only Enterobacter cloacae, Citrobacter freundii, Serratia marcescens, and Morganella morganii. The MIC50 of cedpodoxime for coagulase-negative staphylococci is greater than 2 mg/L, while the MIC for Staphylococcus aureus strains is 4 mg/L. In comparison with other orally absorbable cephalosporins, cefpodoxime is slightly less active than cefixime, cefetamet, and cefotiam against Gram-negative bacteria, but more active than cefuroxime, cefaclor, and cefalexin. Against staphylococci, the activity of cefpodoxime is comparable to that of cefotiam and cefuroxime, and superior to that of cefaclor, while cefixime and cefetamet have insufficient activity against these species. In common with other cephalosporins, cefpodoxime has no activity against enterococci. In vitro models simulating human serum cefpodoxime concentrations demonstrate that a dosage regimen of 200mg is probably sufficient to treat most infections. However, further study is needed to clarify whether infections due to bacteria such as S. aureus, with higher cefpodoxime MICs, can be treated with this dose regimen.

Concentrations of cefpodoxime in plasma, ejaculate and in prostatic fluid and adenoma tissue

Twenty-four healthy volunteers and 24 patients undergoing transurethral resection of the prostate received an oral dose of 200 mg of cefpodoxime as proxetil ester in a fasting state. At the same time 3.235 g of iohexol, a renal contrast medium, was injected intravenously to indicate possible urinary contamination of the prostatic fluid. The subjects were divided into three groups each. After 3, 6 and 12 h the cefpodoxime concentrations were measured in plasma, urine, prostatic fluid and ejaculate in volunteers and in plasma, prostatic fluid and prostatic adenoma tissue in patients by a bioassay as well as by an HPLC method. In general, the concentrations measured by bioassay were higher than those by HPLC. The median plasma concentrations (bioassay) in volunteers (patients) after 3, 6 and 12 h were 2.28 (2.34) mg/l, 0.95 (1.17) mg/l and 0.12 (0.28) mg/l, respectively. The median ejaculate concentrations after 6 and 12 h were 0.95 mg/l and 0.19 mg/l, respectively. Only in three volunteers and in one patient prostatic fluid concentration without urinary contamination could be measured after 3 h with a median fluid to plasma ratio of 0.10. The prostatic adenoma tissue concentrations (bioassay) after 3 and 6 h were 0.50 mg/kg and 0.24 mg/kg with tissue to plasma ratios of 0.30 and 0.26, respectively. After 3 h about half of the volunteers and after 12 h about half of the patients showed no detectable concentration in ejaculate (volunteers) and prostatic tissue (patients), respectively. It was concluded that the cefpodoxime should be administered 3 to 6 h prior to surgery if used for perioperative prophylaxis.(ABSTRACT TRUNCATED AT 250 WORDS)

Cefpodoxime proxetil in upper respiratory tract infections

Cefpodoxime proxetil is a new third generation oral cephalosporin, which shows potent antibacterial activity against both Gram-positive and Gram-negative bacteria, and high stability in the presence of beta-lactamases. Low concentrations of cefpodoxime inhibit most respiratory pathogens, including Haemophilus influenzae, Streptococcus pneumoniae, and Moraxella (Branhamella) catarrhalis. Cefpodoxime reaches concentrations of 0.24 +/- 0.06 mg/kg in tonsils, 0.89 +/- 0.80 mg/kg in lung parenchyma, and 0.91 +/- 0.01 mg/kg in bronchial mucosa; these values exceed by far the minimum inhibitory concentrations (MICs) of cefpodoxime for respiratory pathogens. Preliminary clinical studies were carried out in 181 patients with upper respiratory tract infections: the results indicated an overall clinical response in 88.4% of patients; in 30% the clinical efficacy was excellent and in 58.5% it was good. Further studies showed clinical cure in 90.3% of patients with pharyngotonsillitis, and clinical efficacy (cure plus improvement) in 95% of those with acute sinusitis. Moreover, bacterial eradication was obtained in 78 to 96.7% of cases, most of which involved H. influenzae, streptococci, or M. catarrhalis. Cefpodoxime appears to be an effective new antibacterial that can be recommended as a drug of first choice in the treatment of most upper respiratory tract infections.

Cefpodoxime proxetil in patients with endstage renal failure on hemodialysis

The blood levels of cefpodoxime of 16 hemodialysis patients were monitored after a single oral of Cefpodoxime proxetil with a Cefpodixime-equivalent of 200 mg dose. Eight patients were on dialysis during the period of observation, while the other eight patients were observed during a non-dialysis period. During hemodialysis the cefpodoxime levels were determined before and after the capillary dialyzer. It became apparent that hemodialysis patients have considerably higher and longer-lasting concentrations than patients with normal kidney function. The area under the curve is about seven times greater. Cefpodoxime is thus apparently eliminated to a great extent renally. The concentration levels before capillary dialyzer are noticeably higher than those after capillary dialyzer, so that it can be assumed that cefpodoxime is being dialyzed: the area under the curve of the eight patients observed during hemodialysis was about 50% less than that of the patients observed while not on hemodialysis. Based on the pharmacokinetic data gathered, simulations of the course of concentration were made which took into consideration the clinical circumstances (normal period of dosage administration and dialysis). According to these simulations one can recommend a loading dose of 200 mg and thereafter a dose of 100 mg 12 h later followed by 100 mg every 24 h. This will result in an average concentration of 2 mg/l and never falling below 1.5 mg/l. With this schedule all bacteria considered to be sensitive can be reached. Cefpodoxime proxetil thereby ensures a simple and effective therapy of bacterial infections in hemodialysis patients.

Cefixime

Cefixime is a new orally active third-generation cephalosporin with a broad spectrum of activity against a variety of both gram-positive and -negative bacteria including many beta-lactamase-producing strains of streptococci, Haemophilus influenzae, Neisseria gonorrhoeae, and the majority of the Enterobacteriaceae. Activity of cefixime against Staphylococcus aureus, enterococci, Listeria monocytogenes, and Pseudomonas spp. is poor. The relatively long elimination half-life of cefixime (approximately 3.0 h) has made possible once- to twice-daily administration with the potential added benefit of improved patient compliance. Clinical trials indicate that cefixime is at least as effective as standard agents in the treatment of genitourinary and upper respiratory tract infections. The incidence of resistant organisms reported during clinical trials with cefixime was low. Adverse reactions observed during clinical trials were relatively uncommon and generally mild and transient in nature. The most significant adverse reactions reported were diarrhea and stool changes occurring in up to 20 percent of patients.

Antibiotics in acute pancreatitis. Current status and future directions

Infectious complications currently account for 80 percent of deaths from acute pancreatitis. The adjunctive role of antibiotics in the prevention and treatment of secondary pancreatic infections has received insufficient attention. Randomized clinical studies of effective antibiotics for prophylaxis or empiric therapy of pancreatic infections do not currently exist. In their absence, it is not known whether prophylactic antibiotics are useful in patients with acute pancreatitis. Until such studies are available, if antibiotics are to be used, their choice must be based upon indirect criteria: the ability of the antibiotic to effectively penetrate pancreatic tissue and juice, knowledge of the most common pancreatic pathogens, and the ability of the antibiotic to exceed the in vitro concentration (MIC-90) in pancreatic juice for the common pathogens. Recognition of the limited state of knowledge regarding antibiotics in acute pancreatitis may stimulate future investigations.

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.

beta-Lactamase stability and in vitro activity of oral cephalosporins against strains possessing well-characterized mechanisms of resistance

The in vitro activity of four oral cephalosporins was assessed in dilution tests with 50 isolates of the family Enterobacteriaceae possessing well-characterized mechanisms of resistance to beta-lactam antibiotics. The interaction of the drugs with a broad array of beta-lactamases was also determined in spectrophotometric assays and tests for enzyme induction. Overall, the percentages of strains susceptible to each of the study drugs were 82% for cefixime, 62% for cefuroxime, 58% for cephalexin, and 44% for cefaclor. The poor activity of the older cephalosporins was due to a high degree of susceptibility to hydrolysis by both plasmid-mediated and chromosomally mediated beta-lactamases. For cefaclor, higher MICs were associated with higher levels of plasmid-mediated beta-lactamases in the strains. Resistance to cefuroxime was seen primarily among strains expressing high levels of class I or IV beta-lactamase. Resistance to cefixime was seen only among strains expressing high levels of class I enzymes. Neither cefixime nor cefuroxime was a strong inducer of class I beta-lactamases, although enzyme induction did appear to play a role in cefuroxime resistance in a strain of Serratia marcescens. The consistently greater activity of cefixime over cefuroxime was found not to be due to greater drug permeation into the cell. Rather, it appeared to result from the high affinity of the drug for target enzymes.

In vitro activity of cefpodoxime proxetil (U-76,252; CS-807) against clinical isolates of Branhamella catarrhalis

Cefpodoxime proxetil (U-76,252; CS-807) is a new esterified oral cephem antibiotic with a broad antibacterial spectrum. Since data regarding the activity of cefpodoxime against Branhamella catarrhalis are limited, we tested its activity against 200 B. catarrhalis isolates. The drug was highly active against beta-lactamase-negative and -positive isolates; 99% of all strains tested showed a cefpodoxime proxetil MIC of less than or equal to 2.0 micrograms/ml.