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Objectives: Oral treatment of febrile urinary tract infections (FUTIs) can be impaired by MDR Enterobacterales often combining ESBL and inhibitor-resistant genes. We studied the impact of β-lactamases and Enterobacterales' genotypes on the cefixime, cefpodoxime and mecillinam ± amoxicillin/clavulanate MICs., Materials and Methods: In this multicentric study, we included 251 previously whole-genome-sequenced ESBL-producing Enterobacterales, isolated in French children with FUTIs. The MICs of cefixime, cefpodoxime, mecillinam alone and combined with amoxicillin/clavulanate were determined and analysed with respect to genomic data. We focused especially on the isolates' ST and their type of β-lactamases. Clinical outcomes of patients who received cefixime + amoxicillin/clavulanate were also analysed., Results: All isolates were cefixime and cefpodoxime resistant. Disparities depending on blaCTX-M variants were observed for cefixime. The addition of amoxicillin/clavulanate restored susceptibility for cefixime and cefpodoxime in 97.2% (MIC50/90 of 0.38/0.75 mg/L) and 55.4% (MIC50/90 of 1/2 mg/L) of isolates, respectively, whatever the ST, the blaCTX-M variants or the association with inhibitor-resistant β-lactamases (34.2%). All isolates were susceptible to mecillinam + amoxicillin/clavulanate with MIC50/90 of 0.19/0.25 mg/L, respectively. Neither therapeutic failure nor any subsequent positive control urine culture were reported for patients who received cefixime + amoxicillin/clavulanate as an oral relay therapy (n = 54)., Conclusions: Despite the frequent association of ESBL genes with inhibitor-resistant β-lactamases, the cefixime + amoxicillin/clavulanate MICs remain low. The in vivo efficacy of this combination was satisfying even when first-line treatment was ineffective. Considering the MIC distributions and pharmacokinetic parameters, mecillinam + amoxicillin/clavulanate should also be an alternative to consider when treating FUTIs in children., (© The Author(s) 2021. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Objectives: To establish the epidemiological cut-off values (ECOFFs) for cefoselis against Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae, Proteus mirabilis and Pseudomonas aeruginosa., Methods: We collected 2288 non-repetitive clinical isolates from five laboratories throughout four cities in China. The cefoselis MICs and inhibition zone diameters for all isolates were established using the broth microdilution method and the disc diffusion method following EUCAST guidelines. MIC ECOFFs were determined by visual estimation and ECOFFinder software. Zone diameter ECOFFs were set if a high correlation of MICs and inhibition zone diameters was found by Pearson correlation. Zone diameter ECOFFs were finally determined by the visual estimate method., Results: MICs of cefoselis were distributed from 0.008 to >256 mg/L for the four Enterobacterales species and from 0.25 to >256 mg/L for P. aeruginosa. MIC ECOFFs were 0.125 mg/L for E. coli, K. pneumoniae and P. mirabilis, 0.25 mg/L for E. cloacae and 32 mg/L for P. aeruginosa. A high correlation of MICs and zone diameters was observed for all Enterobacterales (|r| > 0.8, P < 0.001) and a relatively high correlation was found for P. aeruginosa (|r| = 0.71, P < 0.001). The zone diameter ECOFF was 24 mm for E. cloacae, E. coli and K. pneumoniae, 26 mm for P. mirabilis and 21 mm for P. aeruginosa., Conclusions: We determined MIC and zone diameter ECOFFs for cefoselis against four Enterobacterales species and P. aeruginosa. The establishment of ECOFFs for cefoselis provides clinicians with helpful guidance to differentiate WT and non-WT pathogens., (© The Author(s) 2021. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Objectives: To describe the phenotypic and genetic characteristics of the first two cases of extended-spectrum cephalosporin (ESC)-resistant Neisseria gonorrhoeae in South Africa, one of which was associated with verified cefixime treatment failure., Patients and Methods: Two ESC-resistant N. gonorrhoeae isolates were cultured from the urethral discharge of two men who have sex with men (MSM). One man reported a persistent urethral discharge that had failed to respond to previous therapy with oral cefixime. Agar dilution MICs were determined for eight antibiotics. β-Lactam-associated resistance mutations were identified through PCR-based amplification and sequencing for several key genes: penA, mtrR and its promoter, porB1b (penB), ponA and pilQ. For molecular epidemiological characterization, full-length porB gene sequencing, N. gonorrhoeae multiantigen sequence typing (NG-MAST) and multilocus sequence typing (MLST) were performed., Results: Both isolates were resistant to cefixime, ciprofloxacin, penicillin and tetracycline and intermediate/resistant to azithromycin, but susceptible to ceftriaxone, gentamicin and spectinomycin. Both isolates had the type XXXIV penA mosaic allele in addition to previously described resistance mutations in the mtrR promoter (A deletion), porB1b (penB) (G101K and A102N) and ponA1 (L421P). Both isolates had an identical NG-MAST sequence type (ST4822) and MLST sequence type (ST1901)., Conclusions: Both isolates were resistant to cefixime and possessed a number of identical mutations in key genes contributing to ESC resistance in N. gonorrhoeae. The two isolates contained the type XXXIV penA mosaic allele and belonged to a successful international MSM-linked multidrug-resistant gonococcal clone (MLST ST1901) associated with several cefixime treatment failures in Europe and North America.

Objectives: Aminopenicillin-induced exanthema poses a problem in the management of infectious diseases. Due to theoretically possible immunological cross-reactivity, all beta-lactam drugs, i.e. penicillins, penicillin derivatives and cephalosporins, are usually avoided. The available alternative antibiotics (macrolides, quinolones and glycopeptides) may be less effective, have more side effects, and their use increases medical costs. Moreover, their use contributes to the increasing bacterial resistance to antibiotics. The aim of the study is to demonstrate that patients with aminopenicillin-induced exanthema may receive specific beta-lactams for future antibiotic therapy., Methods: Skin testing followed by oral challenges to identify beta-lactams that are tolerated by patients despite confirmed delayed-type non-immunoglobulin E (IgE)-mediated allergic hypersensitivity to aminopenicillins., Results: Sixty-nine out of 71 patients (97.2%) with non-IgE-mediated allergic hypersensitivity to aminopenicillins tolerate cephalosporins without an aminobenzyl side chain such as cefpodoxime or cefixime and 51 patients (71.8%) also tolerate phenoxymethyl penicillin., Conclusions: The majority of patients with non-IgE-mediated allergic hypersensitivity to aminopenicillins do not cross-react to certain cephalosporins or phenoxymethyl penicillin. Skin and drug challenge tests can be helpful to determine individual cross-reactivity.

Objectives: To establish a suitable screening test for the detection of extended-spectrum beta-lactamases (ESBLs) in Haemophilus influenzae., Methods: Double disc diffusion tests using cephalosporin discs adjacent to an amoxicillin/clavulanate 3 microg disc, prediffusion tests, where an amoxicillin/clavulanate 3 microg disc was prediffused before being replaced with a cephalosporin disc, and combination cephalosporin/clavulanate discs were used to screen recombinant H. influenzae expressing cloned ESBLs. Methods initially determined to be suitable were validated by testing a range of clinical strains., Results: Enhanced zones around cephalosporin discs due to synergy with an adjacent amoxicillin/clavulanate disc were not reliably demonstrated with the recombinant H. influenzae strains expressing ESBLs. Cefotaxime 5 microg or 30 microg and cefpodoxime 10 microg discs prediffused with an amoxicillin/clavulanate 3 microg disc, and cefotaxime 30 microg/clavulanate 10 microg and cefpodoxime 10 microg/clavulanate 1 microg combination discs all gave zone sizes > or = 5 mm greater than the corresponding plain disc for all recombinant ESBL-producing strains. None of the clinical strains gave enhanced zones., Conclusions: Cefotaxime 5 or 30 microg or cefpodoxime 10 microg discs prediffused with an amoxicillin/clavulanate 3 microg disc, or cefotaxime 30 microg/clavulanate 10 microg and cefpodoxime 10 microg/clavulanate 1 mug combination discs are all suitable for screening H. influenzae isolates for the presence of ESBLs. ESBL-producing strains should show an increase in zone diameter of > or = 5 mm compared with the corresponding plain cephalosporin disc.

Antimicrobial resistance is universally recognized as a major problem. A European resistance survey was established to monitor the activity of widely used oral antibiotics against common respiratory tract pathogens. Studies were conducted in Italy, Spain and Austria to monitor resistance patterns among respiratory Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, Streptococcus pyogenes, Staphylococcus aureus and Klebsiella pneumoniae to amoxicillin, co-amoxiclav, penicillin, cefaclor, cefadroxil, cefalexin, cefprozil, cefuroxime, cefixime, ceftibuten, cefpodoxime, clarithromycin and azithromycin (the antibiotics tested varying slightly from country to country). Minimum inhibitory concentrations were determined using the NCCLS-recommended broth microdilution method. Among the antibiotics tested, cefpodoxime, an oral cephalosporin, was remarkably active against the major respiratory pathogens in all three countries. Cefpodoxime was more potent than cefaclor, cefixime and ceftibuten against pneumococci, especially against strains with decreased sensitivity to penicillin, and more active than cefaclor and cefuroxime against Gram-negative respiratory pathogens. Pneumococci and staphylococci displayed a very high level of in vitro macrolide resistance. These data indicate that cefpodoxime represents an appropriate choice in the treatment of community-acquired respiratory tract infection in the three countries surveyed.

Microdialysis is a technique that allows the measurement of concentrations of free antibiotic in tissue. The free antibiotic concentration is responsible for the antibacterial effect at the target site. We used microdialysis in animal and human studies to investigate the tissue penetration of cefpodoxime. In the animal study, total plasma and free muscle and lung concentrations of cefpodoxime were measured after male Wistar rats had received either 10 mg/kg or 20 mg/kg i.v. cefpodoxime over 5 h or a continuous i.v. infusion of 260 microg/h cefpodoxime after a loading dose of 6 mg/kg. Free muscle concentrations of cefpodoxime were similar to free lung concentrations and therefore provided a surrogate measure of cefpodoxime concentrations at the pulmonary target site. In an open, randomized, two-way crossover, single-dose study in six healthy male volunteers, total plasma and free muscle concentrations were measured after a single oral dose of cefpodoxime 400 mg or cefixime 400 mg. The total plasma concentrations of each antibiotic were similar and higher than free muscle concentrations. The tissue penetration of cefpodoxime was, however, greater than that of cefixime, as shown by two-fold higher peak free muscle concentrations after dosing with cefpodoxime than with cefixime (2.1 mg/L versus 0.9 mg/L). In addition, the area under the curve for tissue (AUC(t)) of cefpodoxime (400 mg) was more than double that of cefixime (400 mg), based on free antibiotic concentrations (15.4 mg x h/L versus 7.3 mg x h/L). These findings indicate that, taking into account pharmacokinetic/pharmacodynamic considerations, cefpodoxime is likely to be more efficacious than cefixime, due to its greater tissue penetration.

Acute otitis media (AOM), sinusitis and tonsillopharyngitis are respiratory tract infections frequently encountered by primary-care physicians. Increasing bacterial resistance, particularly in Streptococcus pneumoniae, which is one of the most important respiratory tract bacteria implicated in community-acquired respiratory tract infections, has led to concern about the current options for empirical antibiotic treatment and has prompted a search for effective alternative treatments. Data from in vitro studies show that cefpodoxime has good activity against the main respiratory tract pathogens, S. pneumoniae, Haemophilus influenzae, Moraxella catarrhalis and Streptococcus pyogenes. Clinical studies confirm the efficacy of cefpodoxime in AOM, sinusitis and tonsillopharyngitis. As with all broad-spectrum antibiotics, there is the risk of promotion of bacterial resistance associated with overuse. However, if used with care, cefpodoxime can be considered as an alternative for empirical treatment of bacterial respiratory tract infections encountered in general practice, particularly where penicillins and macrolides have reduced efficacy against the main bacterial pathogens.

Thirty healthy volunteers in three groups participated in a study of the effect on the intestinal microflora of oral supplementation with Bifidobacterium longum, Lactobacillus acidophilus and oligofructose, an indigestible oligosaccharide, during oral administration of cefpodoxime proxetil bd for 7 days. Those in group A also received an oral supplement with c.1011 cfu of B. longum BB 536 and L. acidophilus NCFB 1748 and 15 g oligofructose daily, those in group B received a supplement with oligofructose only and those in group C received placebo, for 21 days. In all three groups there was a marked decrease in aerobic microorganisms, involving mainly a rapid and almost complete disappearance of Escherichia coli (P: < 0.05) during antimicrobial administration and, thereafter, an overgrowth of enterococci (P: < 0.05). The number of intestinal yeasts also increased significantly (P: < 0.05) in groups A and B over the same period. There was a dramatic decrease in anaerobic microorganisms on day 4 of administration, mainly caused by loss of bifidobacteria (P: < 0.05) in all groups. The number of lactobacilli also decreased but was significantly higher in group A than in group C at the end of cefpodoxime proxetil administration. Clostridium difficile was found in only one person from group A, but six persons each in groups B and C. Of the bifidobacterial strains isolated from the faecal samples in group A, one was similar to the strain of B. longum administered, but most volunteers were colonized by several different strains of B. longum during the investigation period. The administered strain of L. acidophilus was recovered from six patients in group A.

In-vitro killing curves, a protection model in immunocompetent mice and an ex-vivo model in volunteers were used to evaluate the efficacy of amoxycillin, cefuroxime axetil and cefpodoxime proxetil against a penicillin-intermediate-resistant Streptococcus pneumoniae (MIC = 1 mg/L) (PRP) and a penicillin-susceptible S. pneumoniae (MIC = 0.01 mg/L) (PSP). In vitro, the maximal bactericidal activity was obtained with amoxycillin (1 x MIC versus 2 x MIC cefpodoxime and 4 x MIC cefuroxime). Mice were challenged by intraperitoneal inoculation and treated orally every 8 h for 48 h with 2.5, 5, 7.5 and 10 mg/kg doses of these three beta-lactams. The rate of survival for the PSP strain was 100% with any dose of the three tested antibiotics. For the PRP strain only amoxycillin showed 100% survival with 5, 7.5 or 10 mg/kg doses. Twelve healthy volunteers were randomized in three groups and each received two doses of the oral antibiotic. Blood samples were collected from each subject 0.5 h and 2 h after drug administration and serum inhibitory and bactericidal titres were measured. Similar values were obtained with the three beta-lactams against PSP but against PRP only the serum of volunteers that had taken amoxycillin exhibited serum bactericidal titres of > or = 8. This study suggests a more predictable therapeutic efficacy against pneumococcal infection with amoxycillin than with available oral cephalosporins.

The serum bactericidal activity of three oral cephalosporins was studied in 12 volunteers, after administration of single doses of cefuroxime axetil 250 mg, cefixime 200 mg, cefixime 400 mg and cefetamet pivoxil 500 mg. Serum bactericidal activity against clinical isolates of Streptococcus pyogenes, Streptococcus pneumoniae, Haemophilus influenzae and Klebsiella pneumoniae was measured by a standardized microdilution method. Cefuroxime axetil demonstrated the best bactericidal activity against Gram-positive organisms and cefixime was the most bactericidal against Gram-negative bacteria.

MICs of 21 beta-lactams were determined by agar dilution against 283 penicillin-susceptible (pen-S), 122 intermediate (pen-I) and 23 fully penicillin-resistant (pen-R) pneumococci. MICs of all beta-lactams increased with increasing MICs of penicillin. Clometocillin was the most active penicillin against pen-I or pen-R pneumococci. All oral cephalosporins except cefuroxime and cefpodoxime were less active than penicillin and none was satisfactory against pen-I or pen-R pneumococci. The parenteral third- and fourth-generation cephalosporins (except ceftazidime) were similar in activity to penicillin against pen-S isolates. Cefpirome showed the lowest mean MICs against pen-I and pen-R strains.

The activity of methicillin, oxacillin, vancomycin, imipenem and FK037 against 106 isolates of staphylococci was assessed using a microbroth dilution method with low (10(5) cfu/mL) and high (10(7) cfu/mL) inoculum sizes. Overall, FK037, an oxime-type cephem antibiotic, was as active as imipenem, but less active than vancomycin (MIC90s 25, 25 and 6.25 mg/L, respectively) at the lower inoculum. Efficiency of plating experiments were also performed to characterize phenotypic expression of resistance to FK037, imipenem and methicillin. Five of 24 isolates and 18 of 24 isolates contained subpopulations resistant to FK037 and imipenem, respectively. In a rabbit model of endocarditis, FK037 was equally effective as other antibiotics tested in the treatment of methicillin-sensitive Staphylococcus aureus infection. In the treatment of endocarditis due to a homotypic methicillin-resistant S. aureus, FK037 and vancomycin were the most active antibiotics. The presence of subpopulations resistant to imipenem and FK037, as demonstrated by efficiency of plating and high inoculum MIC testing, did not correlate with antibiotic effectiveness in the rabbit model of endocarditis. Cultures of vegetation material following treatment with imipenem and FK037 demonstrated a lower frequency of organisms resistant to FK037 when compared with imipenem. Thus FK037 shows in-vitro and in-vivo activity against some methicillin-resistant staphylococcal species.

The in-vitro effects of new quinolones and oral cephem antibiotics in various combinations on 26 strains of clinically isolated Serratia marcescens were assessed. The in-vitro activities of ofloxacin and ciprofloxacin in combination with either cefpodoxime or cefcamate were evaluated by the chequerboard titration method. These combinations showed synergistic and additive effects against most of the S. marcescens tested but no antagonism was observed. Time-kill experiments performed with two representative isolates of S. marcescens showed synergic effects with respect to the kill rates, when concentrations of quinolones and beta-lactam antibiotics, exhibiting bacteriostatic effects were combined. Exposure of S. marcescens to ciprofloxacin before the addition of cefpodoxime had no influence on the combination effect. When cefpodoxime was added first, however, the bactericidal effect was reduced. The induction of beta-lactamase by cefmetazole was enhanced by the combination of ciprofloxacin and cefmetazole. These results suggest that the synergic effects observed between new quinolones and cephem antibiotics are due to the stimulation of incorporation of cephems by combination with quinolones.

Cefpodoxime proxetil was administered to 36 children undergoing tonsillectomy, adenoidectomy or both. It was very well tolerated. The detectable tissue concentrations of cefpodoxime were moderate but remained constant (approximately 0.05 mg/kg) 3, 6, and 12 h after the last dose of the drug, while the respective plasma concentrations were declining. This suggests the possibility of twice-daily administration. However, 30% of children did not have quantifiable concentrations in the tonsil and more than half the adenoids did not have quantifiable levels. Whether a higher dosage would lead to higher and more satisfactory tissue concentrations is a matter for further investigation.

A multicentre open-label, randomised trial was performed to compare the efficacy and safety of cefpodoxime proxetil bd and cefaclor tds in the treatment of acute otitis media in children. A total of 167 children aged from 1 month to 11 years were enrolled in five centres: 78 treated with cefpodoxime and 83 treated with cefaclor, were evaluated in the ITT analysis. After tympanocentesis and culture of middle ear fluid, a pathogen was isolated from 85 (53%) of the 161 evaluable patients for the ITT analysis. The organisms isolated were as follows: Streptococcus pneumoniae: (n = 33, 37.5%); Haemophilus influenzae: (n = 22, 25%); Staphylococcus aureus: (n = 15, 17.1%); Streptococcus pyogenes: (n = 8, 9.1%); Moraxella catarrhalis: (n = 2, 2.3%); others (n = 6, 6.8%). Success (defined as a satisfactory clinical outcome, either cure or improvement) was achieved at the end of treatment, in 93.6% of ther patients in the cefpodoxime group and 91.6% of the patients in the cefaclor group (P> 0.05). Clinical recurrence was identified at the follow-up visit (30 days after inclusion), in 6.4% of the cefpodoxime-treated patients and 7.2% of the cefaclor-treated patients (P> 0.05). The drugs were well tolerated by 78/79 (99%) of patients in the cefpodoxime-treated group and 80/85 (94%) in the cefaclor-treated group. The incidence of adverse effects was higher in the cefaclor group than in the cefpodoxime group, but this was not statistically significant (P > 0.05). IN conclusion, cefpodaxime proxetil administered bd is as effective as cefaclor administered tds in the treatment of acute otitis media in children. The less frequent dosing schedule of cefpodoxime (bd) compared with cefaclor (tds) appears to be more convenient for the treatment of the infections in children.

The presence of human granulocytes and monocytes increased the activity of cefetamet against non-ingested Staphylococcus aureus. During ingestion of S. aureus by granulocytes, the activity of cefetamet was equal to that found in the absence of cells. Enhanced activity of cefetamet 30 mg/L was observed during ingestion of S. aureus by monocytes. The effect of cefetamet on S. aureus ingested by granulocytes was much less than that on bacteria in a liquid medium, the maximum growth inhibition (ERmax) being 0.15 and 0.90 log/h, respectively. The concentration at which 50% of the maximum effect was achieved (EC50) was 19.7 mg/L under both conditions. Cefetamet was also more active against S. aureus ingested by monocytes than against bacteria in medium (ERmax 0.97 and 0.77 log/h, respectively). The EC50 under both conditions was 9.7 mg/L. The granulocyte-associated concentration of cefetamet was about on third of that in medium, whereas the monocyte-associated concentration was about two thirds of that in medium. The low intracellular activity of cefetamet against S. aureus ingested by granulocytes is explained primarily by the minimal intracellular growth of bacteria.

The in-vitro activity of the parenteral cephem FK-037 was compared to those of cefpirome, ceftazidime, cefuroxime, cefixime, amoxycillin and co-amoxiclav. Against the Enterobacteriaceae FK-037 was generally > or = 16-fold more active than cefuroxime and two- to four-fold more active than ceftazidime and similar in activity to cefpirome. Pseudomonas aeruginosa displayed similar susceptibilities to ceftazidime and FK-037 (MIC90 4 and 8 mg/L respectively). Methicillin-resistant Staphylococcus aureus were inhibited by < or = 4 mg/L of FK-037. The MIC of FK-037 for 90% of Streptococcus pneumoniae was 0.5 mg/L. Haemophilus influenzae and Moraxella catarrhalis were inhibited by < or = 2 mg/L FK-037.

Forty-four healthy volunteers were given either amoxycillin (ten subjects), cefpodoxime proxetil (ten subjects), ceftibuten (14 subjects) or cefuroxime axetil (ten subjects) orally for 7-10 days, in order to study the ecological effects on the intestinal microflora. In all three groups receiving oral cephalosporins there was a significant increase in beta-lactamase activity during administration (P < 0.05). There was also an inverse correlation between enzyme activity in faeces during administration compared with the concentration of drug in the intestines and the level of ecological disturbance in the normal intestinal microflora. In volunteers given amoxycillin, only small alterations in the faecal microflora were observed although overgrowth by new amoxycillin resistant enterobacteria occurred in all volunteers. There was an overgrowth of enterococci and yeasts during treatment with cefpodoxime proxetil, ceftibuten or cefuroxime axetil, whereas the numbers of enterobacteria were reduced. Colonization with resistant enterobacteria did not occur, but 14 of 34 subjects receiving oral cephalosporins were colonized by Clostridium difficile. Side-effects were mild and not associated with the ecological alterations in the intestinal microflora.

In-vitro antimicrobial activity of cefpodoxime was evaluated against several microbial species by both conventional tests and additional parameters which take into consideration some of the conditions likely to be encountered in infected tissues. MICs for 414 recent clinical isolates, including staphylococci, streptococci, Haemophilus influenzae, Moraxella catarrhalis, several Enterobacteriaceae, Aeromonas hydrophila and Campylobacter jejuni were determined. MIC values overall were similar to those observed for strains from other geographical areas. Inhibition of growth by cefpodoxime was virtually unaffected by the inoculum size, even using bacterial populations as large as 10(9) cfu of Staphylococcus aureus, Streptococcus pyogenes, Streptococcus pneumoniae, H. influenzae, beta-lactamase-negative M. catarrhalis, Escherichia coli, Klebsiella pneumoniae and Proteus mirabilis. Growth in the presence of human serum as the only source of nutrients did not significantly affect the inhibition exerted by cefpodoxime, even against large bacterial populations of S. aureus, S. pneumoniae, E. coli, and K. pneumoniae. For K. pneumoniae, E. coli, P. mirabilis and beta-lactamase-negative M. catarrhalis it was also found that sub-MIC concentrations of cefpodoxime were still able to inhibit the majority of cells in microbial populations as large as 10(9) cfu. Evaluation of bactericidal activity demonstrated that cefpodoxime concentrations comparable to those achievable in plasma or in the respiratory tract were able to kill rapidly large bacterial populations of S. pneumoniae and S. pyogenes. The bactericidal activity was apparently lower against M. catarrhalis, H. influenzae, S. aureus, E. coli, and K. pneumoniae.

Cefpodoxime proxetil is a new orally administered cephalosporin which has a favorable spectrum of activity against respiratory pathogens. Concentrations of cefpodoxime in serum and bronchial mucosal biopsy were measured in 13 patients without active respiratory tract infection undergoing fibreoptic bronchoscopy. Samples were taken between 1 and 6 h after a single oral dose of cefpodoxime proxetil equivalent to 200 mg of cefpodoxime base. In twelve patients who completed the study, mean serum concentrations were 1.7 mg/L (S.E.M. 0.4) and in ten patients mean bronchial biopsy concentrations were 0.9 mg/L (S.E.M. 0.2). The mean penetration was 54% (S.E.M. 6.1). Cefpodoxime was undetectable in biopsies from two patients. The majority of serum and biopsy concentrations were in excess of the MIC90S for Haemophilus influenzae and Streptococcus pneumoniae. Cefpodoxime proxetil may be worthy of further study in clinical trials in patients with respiratory infections.

The effect of three cephalosporins (cefetamet, cefaclor and Ro 40-6890) upon human granulocytes and their ability to modulate the chemiluminescence response, phagocytose, kill bacteria and generate leukotrienes was studied. In the presence of the cephalosporins there was a significant increase in phagocytosis of Escherichia coli. The bactericidal activity of human granulocytes for several other bacteria was also enhanced. Cefetamet and cefaclor increased the chemiluminescence response of human neutrophils to Pseudomonas aeruginosa and Proteus mirabilis in contrast to Ro 40-68790, which decreased the chemiluminescence response. The cephalosporins decreased the synthesis of leukotrienes from human neutrophils after stimulation with Escherichia coli and Staphylococcus aureus. These data emphasize the immunomodulatory functions of various cephalosporins on cells involved in host defence.

Seventeen patients undergoing tonsillectomy received cefpodoxime proxetil orally in a dose equivalent to 100 mg cefpodoxime 4, 7 or 12 h before operation. Plasma and tonsillar tissue concentrations of cefpodoxime were assayed by a microbiological method. Tonsillar tissue concentrations after 4 and 7 h were 0.24 and 0.09 mg/kg respectively--being 23% of the plasma concentration. The tonsillar tissue concentration after 12 h was less than 0.06 mg/kg. As the MIC for Streptococcus pyogenes is less than 0.06 mg/l, cefpodoxime proxetil may be of value in acute tonsillitis.

E1040 is a new parenteral cephalosporin with a broad antibacterial spectrum and potent activity against Gram-negative bacteria including Pseudomonas aeruginosa. The in-vitro activities of E1040 against clinical isolates of Enterobacter cloacae, Ent. aerogenes, Providencia rettgeri, and Morganella morganii were superior to those of ceftazidime, cefoperazone, cefmenoxime, and cefuzonam. The activities of E1040 against Gram-positive cocci were comparable with those of ceftazidime, but it was less active than cefmenoxime, cefuzonam, and cefoperazone. Against Ps. aeruginosa, E1040 was more potent than the other compounds, with an MIC90 of 0.39 mg/l, 1/16 that of ceftazidime. The in-vitro activity of E1040 was well sustained in vivo as shown by results obtained in experimental infections in mice. In particular, E1040 was the most active drug against Ps. aeruginosa including gentamicin-resistant and beta-lactamase-overproducing strains. Morphological studies using a scanning electron microscope and a phase-contrast microscope showed that E1040 caused spheroplast and bulge formation in Ps. aeruginosa at low concentrations.

Three pharmacokinetic studies involving single oral doses of cefpodoxime proxetil in healthy volunteers are reported. The first study was to determine the absolute bioavailability of cefpodoxime, the second was to study the relationship between the oral dose of cefpodoxime proxetil and pharmacokinetic parameters of cefpodoxime, and the third was to compare the pharmacokinetics of cefpodoxime in healthy young and elderly volunteers. Half the dose of cefpodoxime orally administered as cefpodoxime proxetil in tablet form reaches the systemic circulation, while 80% of the cefpodoxime absorbed is excreted unchanged in urine. The volume of distribution is large (32.3 l). The pharmacokinetics of cefpodoxime were linear in young and elderly subjects after 100 and 200 mg oral doses, which are those used therapeutically. The Cmax was about 1.4 mg/l (after 100 mg) and 2.6 mg/l (after 200 mg). Deviation from linearity appeared at 400 mg and the effect was confirmed at 800 mg. The differences between young and elderly subjects were negligible, with the exception of the half-life which increased by only 14%, from 2.67 to 3 h. Dosage adjustment is therefore not necessary in the elderly.

Eighteen patients of either sex with pleural effusions underwent aspiration 3, 6 or 12 h after receiving a single oral dose of cefpodoxime proxetil equivalent to 200 mg cefpodoxime. The mean concentrations of cefpodoxime in pleural fluid were, respectively, 0.62, 1.84 and 0.78 mg/l for these three time intervals, the corresponding ratios between pleural fluid and plasma concentrations being 0.24, 0.67 and 1.07. The findings indicate that there is good penetration of cefpodoxime into pleural fluid. Concentrations between 3 and 12 h after dosing were equal to or above the MIC90 for most of the organisms commonly found in lower respiratory tract infections.

The in-vitro activity of cefpodoxime, the active compound of the ester prodrug, cefpodoxime proxetil, was compared with that of other antibiotics. The susceptibility of bacterial isolates from patients with respiratory tract infections was determined by an agar dilution method. The MIC90s of cefpodozime for ampicillin-sensitive and beta-lactamase-producing strains of Haemophilus influenzae were 0.12 and 0.25 mg/l, respectively; the MIC90s for ampicillin-resistant non-beta-lactamase-producing strains was 1 mg/l. Time-kill curves of cefpodoxime against ampicillin-sensitive and ampicillin-resistant beta-lactamase producing strains showed a time-dependent bactericidal activity. The MIC90s for ampicillin-sensitive and ampicillin-resistant Branhamella catarrhalis were 0.50 and 1 mg/l, respectively. The MIC90s for penicillin-sensitive pneumococci, beta-haemolytic streptococci and Streptococcus agalactiae were 0.06, 0.06 and 0.12 mg/l, respectively. The inhibitory activity against penicillin-resistant pneumococci was limited: the MIC90 was 4 mg/l.

This European, multicentre trial evaluated the efficacy and tolerance of cefpodoxime proxetil in comparison with co-amoxiclav (amoxycillin plus clavulanic acid) in the treatment of acute exacerbations of chronic bronchitis. The study design was double-blind and double-placebo controlled. Doses of either 200 mg bd of cefpodoxime proxetil or 500 mg/125 mg tds amoxycillin plus clavulanic acid were given orally for 9.6 +/- 1.8 days. Two hundred and fifty-one patients were enrolled in 27 centres in West Germany, France, and Italy. The overall clinical efficacy was 97.2% in the cefpodoxime proxetil group compared with 94.7% in the co-amoxiclav group. Fifty-eight adverse events, mainly gastrointestinal, occurred in 42 patients with no significant difference between the groups. A significant difference in the number of resistant pathogens on pre-treatment culture to the advantage of cefpodoxime was noted. In our experience, both drugs were of similar value in the treatment of respiratory tract infections. Thus, cefpodoxime proxetil should be an effective antibiotic for the treatment of acute exacerbations of chronic bronchitis.

Multiple dose pharmacokinetics of a new third-generation cephalosporin, cefpodoxime, were evaluated in adults (15, 18-60 years) and elderly adults (10, greater than or equal to 70 years), all out-patients suffering from acute lower respiratory tract infection. A dose of 200 mg cefpodoxime proxetil (expressed in mg cefpodoxime) was administered 12-hourly for seven to ten days and timed blood samples were evaluated on days 0, 3, 5, 6/7 and on the last day of treatment. Results showed that the pharmacokinetics in adult and elderly patients were comparable with those of healthy volunteers and with each other, with the exception of one elderly patient with severe renal impairment. Dosage adjustment of cefpodoxime proxetil does not therefore appear to be necessary in the elderly unless there is evidence of severe renal insufficiency.

This multicentre, randomized study compared the efficacy and tolerance of cefpodoxime proxetil and ceftriaxone in vulnerable patients with bronchopneumonia. Patients received cefpodoxime proxetil 200 mg bd orally or ceftriaxone 1 g daily im for a ten-day period. They were evaluated at days 10 and 30. Ninety-six patients were evaluated for tolerance, 85 for clinical efficacy and 65 for bacteriological efficacy. At entry all patients had radiographic evidence of pneumonia and 74% of bacteriological samples were positive. The percentage of overall success (cured or improved) was 97.7% (43/44) in the cefpodoxime proxetil group and 95.1% (39/41) in the ceftriaxone group. The bacteriological efficacy was 94.3% in the cefpodoxime proxetil group and 97.4% in the ceftriaxone group. Clinical tolerance was satisfactory in both groups. In this study, the clinical and bacteriological results obtained with cefpodoxime proxetil were comparable with those obtained with ceftriaxone in the treatment of community-acquired bronchopneumonia in patients with additional risk factors.

A ten day course of oral penicillin is still recommended for pharyngotonsillitis with the aim of eradicating Streptococcus pyogenes and preventing rheumatic fever. However there is some evidence that penicillin V therapy is less satisfactory than in former years. Several explanations have been suggested, including inadequate pharmacokinetic properties, poor patient compliance, penicillin tolerance, re-infection and carrier state, and indirect pathogenicity. In this context we evaluated the efficacy of third generation cephalosporins. We have shown that a short course of five days treatment with cefpodoxime is as effective as the ten days of conventional treatment with penicillin in terms of both clinical and bacteriological efficacy. Moreover the possibility of reducing the duration of therapy and the twice daily administration of these new cephalosporins results in better patient compliance with treatment.

The efficacy of cefpodoxime proxetil has been studied in ten clinical trials conducted in adults suffering from lower respiratory tract infections (pneumonia, acute bronchitis or acute on chronic bronchitis) and upper respiratory tract infections (tonsillitis/pharyngitis or sinusitis). All the trials were controlled, randomized, multicentre and international and seven were double-blind, double-dummy designed. Over a period of 18 months from July 1988 to December 1989, 2448 patients were included. Among them, 2429 (99%) were evaluated for tolerance, 2101 (86%) for tolerance and clinical efficacy and 1018 (42%) for tolerance and clinical and bacteriological efficacy. The clinical response was judged satisfactory in 1205/1263 (95.4%) patients treated with cefpodoxime proxetil and in 788/838 (94%) patients treated with comparative antibiotics. The bacteriological response was judged satisfactory for 662/699 (95%) pathogens for cefpodoxime proxetil treatment versus 427/463 (92, 2%) for comparators. Cefpodoxime proxetil has been given to 7351 patients in the course of its international development with no severe side-effect being observed. Common reactions have been noted with a similar frequency to that seen with the other beta-lactams. No pseudomembranous colitis has been observed during clinical trials. On this basis, cefpodoxime proxetil appears to be efficacious and well tolerated and could be an antibiotic of first choice in the treatment of lower and upper respiratory tract infections in adults and adolescents.

The efficacy and tolerance of cefpodoxime proxetil were compared with those of cefaclor in a multicentre, international, prospective, double-blind, placebo-controlled study in adult outpatients suffering from acute sinusitis. At the end of treatment, cefpodoxime proxetil was more effective than cefaclor, producing complete clinical cure in 84% of cases (102/122) vs 68% of cases (77/114) in the cefaclor group (P = 0.01). The overall clinical efficacy (cure + improvement) was similar in the two groups with 95% (116/122) satisfactory responses in the cefpodoxime proxetil group and 93% (106/114) in the cefaclor group. Bacteriological response was similar with 95% eradication in the cefpodoxime proxetil group (55/58) vs 91% with cefaclor (63/69).

A total of 1834 non-copy, general practice or outpatient isolates were collected by 20 hospital laboratories within the British Isles, and identified and tested for susceptibility to nine antimicrobial agents available by oral administration at one centre. Against Enterobacteriaceae cefpodoxime was the most active beta-lactam agent tested, the MIC90s being: for Escherichia coli 1.0 mg/l, for Proteus mirabilis 1.0 mg/l, for Citrobacter spp. 2.0 mg/l, and for Enterobacter spp., Serratia spp., Morganella spp. and Klebsiella spp. 16-64 mg/l. Cefpodoxime also showed a certain amount of activity against staphylococci and high activity against streptococci, the MIC90s being for Staphylococcus aureus 2 mg/l, for coagulase negative staphylococci 8 mg/l, for Streptococcus pyogenes 0.015 mg/l, for Str. pneumoniae 0.06 mg/l and for Str. agalactiae 0.5 mg/l.

Eighteen patients undergoing thoracotomy for suspected pulmonary neoplasia were given 200 mg cefpodoxime equivalent by mouth, before operation. Plasma samples were obtained before dose administration, and plasma and lung tissue samples were obtained at the time of operation which was 3, 6 or 12 h after the dose. All samples were assayed for cefpodoxime. The mean ratios for lung tissue/plasma concentrations were similar between 3 and 12 h after dose, suggesting that equilibrium between plasma and lung tissue concentrations was reached within 3 h of medication. The mean concentrations of cefpodoxime in lung tissue were 0.63 +/- 0.16, 0.52 +/- 0.09 and 0.19 +/- 0.02 mg/kg at 3, 6 and 12 h after administration, respectively. These observations indicate good, rapid and sustained penetration into lung tissue in concentrations greater than or equal to the MIC90 for most common micro-organisms found in community-acquired pneumonia.

The antibacterial activity of cefpodoxime proxetil was studied in an in-vitro model simulating doses of 100, 200 and 400 mg. Strains of Klebsiella spp. Proteus mirabilis, Escherichia coli, Streptococcus pyogenes, and Haemophilus influenzae were effectively reduced by a dose of 200 mg. While for Esch. coli no dose-activity relationship was observed--the maximal effect was achieved with a simulated dose of 100 mg--Staphylococcus aureus could be reduced effectively only by a simulated dose of 400 mg. The lower doses showed stepwise lower activities. Apart from broad spectrum beta-lactamases like SHV 2 or TEM 5 the presence of plasmid coded beta-lactamases in Esch. coli and H. influenzae did not affect the antibacterial activity of cefpodoxime proxetil. The results show that cefpodoxime was more active against Gram-negative bacteria than amoxycillin, and comparable activity to intramuscular cefotiam in the in-vitro model.

The in-vitro activity of cefpodoxime was studied in 529 clinical isolates and compared with the activity of other oral beta-lactams. Amongst the Enterobacteriaceae cefpodoxime was very active (MIC90 less than or equal to 1 mg/l--other than genera commonly possessing chromosomal beta-lactamases). Against these strains cefpodoxime was comparable in activity to cefixime and about eight-fold more active than cefuroxime and 8-16-fold more active than cefaclor and cephalexin. Staphylococcus aureus strains were moderately susceptible (MIC90 4 mg/l) to cefpodoxime in comparison with cefixime (16 mg/l). The respiratory pathogens, Haemophilus influenzae, Streptococcus pneumoniae and Branhamella catarrhalis were susceptible to less than or equal to 0.5 mg/l cefpodoxime. An increase in inoculum from 10(4) to 10(6) cfu had little effect upon activity. Studies in beta-lactamase hydrolysis of cefpodoxime showed it to be stable to TEM-1, SHV-1 and BRO-1 enzymes but with high affinity for the P99 enzyme. The primary target of cefpodoxime is PBP3 (I50 1 mg/l) in Escherichia coli K12. The protein binding of the agent to human serum was 14.3-18.3% at 1 and 5 mg/l respectively.

The in-vitro activities of trospectomycin, cefpodoxime, cefamandole, cefonicid, and cefuroxime against beta-lactamase-negative and -positive invasive clinical isolates of Haemophilus influenzae type b were determined by the agar dilution method. Trospectomycin and cefpodoxime inhibited 90% of the strains at concentrations of 5 and 0.06 mg/l, respectively, and no differences between the susceptibilities of the beta-lactamase-negative and -positive strains were noted. The activity of cefpodoxime was minimally affected by increased inoculum size, but significant inoculum effects were noted with cefamandole, cefonicid, and cefuroxime with beta-lactamase positive strains.

The minimal inhibitory concentrations (MICs) of nine antibiotics were determined by agar dilution on 123 strains of Streptococcus pneumoniae (65 penicillin sensitive, 42 intermediate resistant and 16 resistant). The antimicrobial agents tested were penicillin G, clindamycin, trospectomycin, daptomycin, teicoplanin, cefpodoxime, ciprofloxacin, ofloxacin and vancomycin. Of these, daptomycin, teicoplanin and vancomycin demonstrated the greatest in-vitro activity against penicillin-resistant strains (MIC90s less than or equal to 0.25 mg/l). Ciprofloxacin, ofloxacin and trospectomycin had equivalent activities unaffected by penicillin-susceptibility (MIC90 of both quinolones 2.0 mg/l, and of trospectomycin 4.0 mg/l). Cefpodoxime was also active in vitro against all strains (MIC90 2.0 mg/l), but MICs increased with increasing penicillin-MICs. Most penicillin-susceptible strains were susceptible to clindamycin, but many penicillin intermediate resistant and resistant strains were resistant to this drug. Results of this study indicate that several newly introduced and experimental antibiotics have potential in the treatment of infections caused by resistant strains of Str. pneumoniae.