Comparison of in vitro activity of cephalexin, cephradine, and cefaclor

[Experience with cefaclor in the treatment of ear, nose and throat infections. Indications for cefaclor therapy (author's transl)]

The efficacy and tolerance of the new oral cephalosporin cefaclor was tested in 61 patients treated for a variety of moderate to severe ENT infections which were not expected to undergo a spontaneous remission without antibacterial therapy. The most frequently isolated pathogens were streptococci and Staphylococcus aureus. The dosage consisted of 500 mg cefaclor three times daily, and the treatment lasted between 4 and 43 days (average 14 days). In 35 cases, some of whom had already been treated unsuccussfully with another antibiotic, the results were very good. In 22 patients locally applied medicaments or surgery contributed to the good result. In four patients an unequivocal evaluation was not possible or therapy was not successful. The frequently noted rapid response to treatment with cefaclor was impressive. No relapses were recorded. In pharmacokinetic studies a cefaclor concentration of 2.8 mcg/g was obtained in the tonsils 90 minutes after oral administration of 1000 mg. Clinical examinations in 61 patients and a complete range of laboratory tests in 47 patients did not reveal any case of allergic reaction. One patient only complained of nausea and diarrhoea. In two patients temporary low grade thrombopenia and thrombocytosis respectively were observed. In several patients a slight transitory rise in transaminases was seen. Cefaclor thus proved to be an effective and well-tolerated antibiotic. Its indications in the treatment of ENT infections are discussed.

[Investigations on the excretion of cefaclor in human bile (author's transl)]

The concentration of cefaclor in serum and bile was determined for up to 360 minutes after a single oral dose of 1 g cefaclor in 18 patients with continuous T-drainage of the bile duct. The rate of absorption varied, there being marked differences in the time. The peak bile concentration of 12.1 mcg/ml was reached after 120 min; the peak serum concentration of 12.3 mcg/ml, on the other hand, was reached after only 90 min. There was no accumulation of cefaclor in the bile.

Cefaclor: summary of clinical experience

Cefaclor, a new semisynthetic cephalosporin antibiotic for oral use, was studied by 62 clinical investigators in six countries in 1493 adult and paediatric patients. The pooled data reveal that satisfactory clinical responses were obtained in 80% of urinary tract infections, 87% of upper respiratory tract infections, 90% of cases of otitis media, 99% of lower respiratory tract infections, and 96% of skin and skin structure infections. Administration of this antibiotic was associated with a low incidence of adverse reactions including gastrointestinal (2.6%) and hypersensitivity (1.5%). Of particular clinical interest were the outstanding results obtained in the treatment of otitis media and lower respiratory tract infections.

[In vitro activity of cefaclor (author's transl)]

A comparative study was conducted on the in vitro activity of cefaclor and other oral cephalosporins against a large number of freshly isolated clinical strains of gram-negative and gram-positive bacteria. The activity of cefaclor against gram-positive pathogens is very similar to that of cephalexin. The action of cefaclor against Streptococcus pneumoniae is superior. Cefaclor is the most active antibiotic against strains of Haemophilus influenzae, and is also more active than cephalexin and cephradine against non-beta-lactamase producing strains of Escherichia coli, Klebsiella species and Proteus mirabilis.

Comparative study of cefaclor and amoxicillin in treatment of urinary tract infection

Cefaclor or amoxicillin was given to 51 randomly assigned patients with urinary tract infections. Inclusion in the study required two pretreatment urine cultures yielding the same organism (susceptible to both antibiotics) in concentrations greater than or equal to 10(5)/ml. Both drugs were administered as 250 mg. orally every eight hours for ten days. Cefaclor was given to 27 patients and amoxicillin to 24. Most patients in both groups had negative urine cultures at five to nine days and four to six weeks following therapy. One patient in each group was unsuccessfully treated. Relapse or reinfection occurred with similar frequency in both treatment groups. Both antibiotics were well tolerated. minimal inhibiting concentrations (MICS) of cefaclor, amoxicillin, cephradine, and cephalexin were determined by an agar dilution technique for the 44 available pretreatment isolates (41 Escherichia coli and 3 Proteus mirabilis). Mean MICs (micrograms./ml., +/- SD) were 2.2 +/- 1.4 for cefaclor, 4.4 +/- 2.0 with amoxicillin, 8.1 +/- 4.2 for cephradine, and 5.7 +/- 3.0 with cephalexin. Cefaclor is highly active in vitro against those gram-negative bacteria which are commonly isolated from urine. Cefaclor is as effective as amoxicillin when administered three times daily for the treatment of urinary tract infection.

[Serum and tissue concentrations after a single dose of cefaclor]

Serum and tissue concentrations of cefaclor were determined a total of 155 and 96 times respectively in 16 volunteers after a single dose of 1 g. At this dosage peak concentrations of 13.5, 14.5 and 13.4 mcg/ml were measured after 60, 90 and 120 minutes respectively. Tissues in which concentrations were measured included cortical bone, spongy bone, muscle, fascia, cutis and subcutis. By measuring blood concentrations of the tissue samples, a division could be made for purposes of calculation into intravascular and extravascular active components. Low amounts of extravascular cefaclor could be established merely in the fascia and in the cutis. The cefaclor concentrations found in spongy bone, muscles and subcutis proved to be determined to a large extent by the intravascular antibiotic. No cefaclor could be detected in cortical bone at the given dosage.

Comparative pharmacokinetics of cephalexin, cefaclor, cefadroxil, and CGP 9000

In a randomized crossover study, the pharmacokinetics of three new cephalosporin antibiotics, cefaclor, cefadroxil, and CGP 9000, in comparison to cephalexin, were determined after oral administration, by capsules, of 1,000 mg on an empty stomach in 12 normal subjects. Serum concentrations were measured during a period of 8 h, and urine recovery was measured during 24 h. The significant parameters of bioavailability of an orally administered substance were determined. The maximal serum concentrations (y(max)) for cephalexin, cefaclor, cefadroxil, and CGP 9000 (in milligrams per liter) were: 38.8 +/- 8.1; 34.6 +/- 7.8; 33.0 +/- 5.4; and 23.3 +/- 7.3, respectively. The areas under the curve (in hours x milligrams per liter) were: 93.0 +/- 14.8; 74.5 +/- 9.9; 70.1 +/- 9.0; and 108.5 +/- 18.4, respectively. In a further crossover study with six subjects, 1,000 mg of cephalexin and of cefadroxil were given during a standard breakfast. The y(max) of cephalexin decreased to 23.1 +/- 6.6 mg/liter, in contrast to cefadroxil, with an unchanged y(max) of 32.7 +/- 3.4 mg/liter.

Pharmacological evaluation of cefaclor in volunteers

The plasma and urine concentrations of cefaclor were measured after oral administration of single and multiple doses to volunteers. Cefaclor was rapidly absorbed, rapidly excreted in the urine, well tolerated without toxicity, and failed to accumulate in the plasma with chronic dosing.

Pharmacokinetics of cefaclor in patients with end stage renal disease and during hemodialysis

A single 1.0-g dose of cefaclor administered to patients with stable end stage renal disease whose creatinine clearances were <5 ml/min produced a mean peak serum concentration of 48.3 +/- 19.8 mug/ml. The half-life was 2.3 +/- 0.3 h. Hemodialysis shortened the half-life of a similar dose to 1.6 +/- 0.3 h. Approximately one-third (340 mg) of the administered drug was recovered in the dialysate. Multiple doses of 500 mg every 6 h between hemodialysis sessions produced effective serum concentrations and no bioassay evidence of drug accumulation.

Pharmacology of cefaclor in normal volunteers and patients with renal failure

After a 500-mg dose of cefaclor, the mean peak plasma level was 12.4 mug/ml and after a 250-mg dose it was 5 mug/ml in normal volunteers. Food intake significantly reduced absorption. Probenecid prolonged plasma levels. Mean plasma half-life in normal volunteers was 0.8 h. Only about 50% of the dose was excreted in the urine within 4 h in normal volunteers. Plasma half-life in patients with renal insufficiency was only about 3 h, which suggests that cefaclor may be eliminated by nonrenal mechanisms in humans. Urinary levels of cefaclor were adequate to inhibit susceptible pathogens even in patients with moderately severe renal failure. Plasma half-life during hemodialysis was 2.1 h and rose to 2.8 h after dialysis.

Susceptibility of Staphylococcus aureus to cefaclor and cephalothin: laboratory and clinical studies

In vitro susceptibility tests of 201 strains of Staphylococcus aureus by agar dilution revealed 90% to be susceptible to 8 mug or less of cefaclor per ml. Strains from hospitalized children and adults were more often resistant than those from patients with bullous impetigo. Cephalothin was more active than cefaclor against all strains tested. Results with disk tests, including those strains examined from the clinical investigation, revealed some discrepancies in identifying strains more resistant to cefaclor. In clinical studies, cefaclor proved quite effective for the treatment of bullous impetigo. Of 73 patients, 90% were cured and 7% improved after completing 5 or more days of treatment. Prompt improvement was noted among most patients seen 3 to 5 days after treatment was begun. One patient experienced mild diarrhea. There were no other adverse or toxic manifestations attributable to therapy.

In vitro susceptibility of Haemophilus influenzae to sulfamethoxazole-trimethoprim and cefaclor, cephalexin, and cephradine

Sulfamethoxazole-trimethoprim and three oral cephalosporins, cefaclor, cephalexin, and cephradine, were evaluated in vitro as possible alternatives to chloramphenicol in the treatment of non-central nervous system infections due to ampicillin-resistant Haemophilus influenzae. Sixty-four isolates of H. influenzae, including 31 beta-lactamase-positive strains, were tested by the agar dilution method. All strains were inhibited by 0.78/0.039 mug sulfamethoxazole-trimethoprim per ml and by 0.78 mug of chloramphenicol per ml. At 6.25 mug/ml, 100, 11, and 3% of all strains were inhibited by cefaclor, cephalexin, and cephradine, respectively. Thus, on the basis of drug concentrations presumably achievable in serum, 100% of strains were susceptible to sulfamethoxazole-trimethoprim, chloramphenicol, and cefaclor. However, a considerable inoculum effect was noted with both beta-lactamase-positive and -negative strains, when tested with sulfamethoxazole-trimethoprim; the minimal inhibitory concentrations of cefaclor were only slightly affected. Also, synergistic effects of sulfamethoxazole-trimethoprim, sulfamethoxazole-erythromycin, and sulfamethoxazole-cefaclor were seen when combinations were tested against both beta-lactamase-positive and -negative strains, as determined by minimal inhibitory concentrations measured by the broth dilution method and by killing curve analyses. These results support further evaluation of these combinations and of cefaclor alone for the treatment of non-central nervous system infections due to H. influenzae.

Cefaclor: in vitro spectrum of activity and beta-lactamase stability

The in vitro activity of cefaclor against 556 clinical isolates of gram-positive and gram-negative bacteria was compared with that of other cephalosporins. Cefaclor had activity similar to that of cephalexin against gram-positive bacteria. It showed greater activity against Haemophilus strains than did cephalexin and inhibited beta-lactamase-producing Haemophilus isolates. Cefaclor was more active than cephalexin or cephalothin against Escherichia coli, Salmonella, and Shigella isolates but did not act against Serratia, Acinetobacter, indole-positive Proteus, or Bacteroides isolates. Cefaclor was resistant to type III (TEM) beta-lactamases but was destroyed by type I beta-lactamases and, to a lesser degree, by type IV and type V beta-lactamases.

Pharmacologic studies with cefaclor, a new oral cephalosporin

Cefaclor, a new oral cephalosporin, was administered to 18 normal human volunteers in either single or multiple doses of 250 and 500 mg. Mean serum concentrations of 6.09 and 12.8 microgram/ml were achieved 1 hour after single oral doses of 250 and 500 mg, respectively. The serum concentrations declined rapidly and no drug was detected at 4 hours. Very high concentrations of cefaclor were found in urine during the first 8 hours after ingestion of the drug. Forty-three per cent of the total dose was excreted in urine during the first 8 hours. There was no accumulation of drug in serum during the multiple-dose studies.

Diffusion disk susceptibility testing with cefaclor

The reliability of the standardized 30-mug cephalothin disk and that of an experimental 30-mug cefaclor disk in predicting probable clinical susceptibility to cefaclor were compared. Quantitative determinations of cefaclor susceptibility were measured by the World Health Organization International Collaborative Study agar dilution procedure; diffusion disk tests were performed by the standardized U.S. Food and Drug Administration disk test. The cephalothin disk erred in predicting probable susceptibility in 52% of isolates of Enterococcus spp. resistant to 16 mug or less of cefaclor per ml; the cefaclor disk did not. The cephalothin disk erred in correctly predicting susceptibility in only 20% of cefaclor-susceptible isolates of Enterobacter spp.; the cefaclor disk correctly predicted susceptibility for 70%. These results indicate the need for further evaluation of a separate cefaclor disk for use in susceptibility testing with this new cephalosporin.

Antimicrobial activity in vitro of cefaclor, a new oral cephalosporin

The antimicrobial activity of cefaclor, a new orally administered cephalosporin derivative, was studied in vitro against a variety of Gram-positive and Gram-negative clinical isolates. Both penicillin-resistant and penicillin-susceptible strains of Staphylococcus aureus were susceptible to cefaclor, with mean MICs of 1.44 and 0.93 microgram/ml, respectively. However, the MBC for penicillin-resistant S. aureus was higher than that for the penicillin-susceptible strains. All strains of Streptococcus pyogenes, Streptococcus viridans, and Streptococcus pneumoniae tested were highly susceptible to cefaclor; all strains of Streptococcus faecalis were highly resistant to cefaclor. Strains of Escherichia coli, Klebsiella sp., Proteus mirabilis, and Hemophilus influenzae were susceptible to cefaclor. Eighty per cent of strains of H. influenzae were inhibited by 5 micrograms/ml of cefaclor. Most strains of Enterobacter sp., indole-positive Proteus, Pseudomonas sp., and Serratia sp. were resistant to cefaclor.

In vitro activity of cefaclor against aerobic and anaerobic bacteria

Cefaclor (CCL), a new cephalosporin, was tested in vitro against 602 (271 anaerobic and 331 aerobic) clinical isolates in comparison with cephalothin, cefazolin, cephradine, and cefamandole. Sixteen micrograms of CCL per ml inhibited 68% of all aerobes tested and 80% of the 211 enteropathogenic organisms (Escherichia coli, Salmonella, and Shigella) isolated from cases of infantile diarrhoea. CCL inhibited 88% of gram-positive anaerobic cocci and 72% of Bacteroides other than B. fragilis at a concentration of 16 mug/ml. B. fragilis and Clostridia were resistant to CCL. Increased inoculum of E. coli from 10(5) to 10(9) increased the minimal inhibitory concentration of CCL and cefamandole by fourfold against 7 of the 64 strains tested. All seven were beta-lactamase negative. No antimicrobial synergism was noted between CCL and penicillin. The in vitro efficacy of CCL, an oral cephalosporin, against enteropathogenic E. coli, if proven safe, may be tested in vivo against such infections.

Comparative in vitro activity of five cephalosporin antibiotics against salmonellae

The in vitro activities of five cephalosporin antibiotics against 121 strains of salmonellae were compared. Cefamandole and cefaclor were more potent than cefazolin, and these three drugs were more active than cephalothin and cephalexin.

In vitro activities of five oral cephalosporins against aerobic pathogenic bacteria

Cefaclor (Lilly 99638) and cefatrizine (BL-S640, SK&F 70771) are orally absorbed, broad-spectrum semisynthetic cephalosporins. They were compared in vitro with cephalexin, cephaloglycin, and cepharadine against a variety of aerobic pathogenic bacteria by an agar dilution procedure. Cefaclor and cefatrizine were found to be similar or superior to cephalexin, cephaloglycin, and cephradine in terms of activity against gram-positive cocci other than enterococci. Only cefatrizine demonstrated any potentially useful activity against some susceptible isolates of enterococci. Cefaclor and cefatrizine also were highly active, equally or more so than the other oral cephalosporins, against several gram-negative species including Escherichia coli, Enterobacter aerogenes, and Klebsiella pneumoniae. None of the cephalosporins were particularly active against Enterobacter cloacae. Both cefaclor and cefatrizine were active against Proteus mirabilis; cefatrizine was uniquely active against indolepositive Proteus species.

Comparison of in vitro antibacterial activity of three oral cephalosporins: cefaclor, cephalexin, and cephradine

Cefaclor, a new oral cephalosporin, was compared in vitro with cephalexin and cephradine against 233 organisms. Evaluations were performed in Mueller-Hinton and nutrient broth and agar using two inoculum sizes. In agar, cefaclor had greater antibacterial activity than either cephalexin or cephradine against isolates of Escherichia coli, Proteus mirabilis, Staphylococcus aureus, Klebsiella pneumoniae, and Salmonella typhi. All three drugs were relatively inactive against isolates of enterococci, Enterobacter species, and indole-positive Proteus. Cefaclor, however, did exhibit the greatest activity of the three antibiotics against these organisms. Although there was wide variability with respect to test parameters, the broth results generally paralleled the agar results. In nutrient broth a clear separation of the results with these three cephalosporins was seen with K. pneumoniae, E. coli, and S. typhi. Cefaclor was the most active, cephalexin had intermediate activity, and cephradine was the least active. From the data obtained in this in vitro study, it can be concluded that cefaclor, which has a substituted chloro group attached to the molecule, had increased antibacterial activity over cephalexin and cephradine. Comparative clinical trials with cefaclor will determine whether the differences outlined above are of clinical significance.

In vitro studies with cefaclor, a new oral cephalosporin

In vitro studies were performed to evaluate the activity of cefaclor in comparison with cephalexin against 180 clinical isolates. Broth dilution susceptibility tests showed cefaclor to be 4- to 16-fold more active than cephalexin against Streptococcus pneumoniae, Haemophilus influenzae, and cephalothin-susceptible Enterobacteriaceae. Neither drug was highly active against cephalothin-resistant Enterobacteriaceae or methicillin-resistant Staphylococcus aureus. Cefaclor zones with 30-mug disks were generally larger than cephalexin zones, 4 mm larger than cephalothin zones against Enterobacteriaceae, and 6 mm smaller than cephalothin zones against S. aureus. Quantitative kill curves indicated that killing by both cefaclor and cephalexin was slow and often incomplete over a 24-h period. Cefaclor-induced filamentation of gram-negative bacilli was not as extensive as that produced by cephalexin, and some spherule formation did occur. However, cefaclor was significantly more unstable in solution than cephalexin, with a half-life of less than 6 h at 37 degrees C. Thus, results obtained in tests after prolonged incubation may not provide an accurate measure of cefaclor's activity.

In vitro activity of cefaclor, a new orally administered cephalosporin antibiotic

The in vitro antibacterial activity of cefaclor, cephalothin, and cephalexin against 261 clinical isolates of Staphylococcus aureus and Enterobacteriaceae was compared. Cefaclor and cephalexin were about equally active against S. aureus. Cefaclor was the most active cephalosporin against Escherichia coli, Proteus mirabilis, and Klebsiella pneumoniae. The effect on the antimicrobial activity using a relatively high and low inoculum was pronounced for cefaclor when compared with that of cephalothin.

In vitro susceptibility studies with cefaclor and cephalexin

The in vitro activity of cefaclor and cephalexin against clinical isolates of four bacterial genera was compared. Both agents had a similar range of activity, but cefaclor was significantly more active by weight than cephalexin for most isolates tested.