In vitro studies of cefamandole

Pharmacokinetics of Cefamandole in Patients Undergoing Continuous Ambulatory Peritoneal Dialysis

The pharmacokinetics of cefamandole have been evaluated in five patients undergoing continuous ambulatory peritoneal dialysis (CAPD). The drug was absorbed rapidly from the peritoneum reaching peak serum concentrations averaging 31.3 mcg/ml. Approximately 72% of the dose instilled into the peritoneum was absorbed over a six hour period. Subsequently cefamandole disappeared from the serum slowly with a mean half-life of 10.4 hours. The volume of distribution was 0.25 I/kg. The calculated total body clearance averaged 20.0 ml/min and the mean dialysis clearance was 3.2 ml/min. The authors postulate that in renal failure patients cefamandole may be eliminated by an alternate route.

Two-day cefamandole versus five-day cephazolin prophylaxis in 965 total hip replacements. Report of a multicentre double blind randomised trial

The aim of this trial was to compare a 5-day course of cephazolin with a regimen of 2 days of cefamandole in 965 total hip replacements (488 in the cefamandole group and 477 in the cephazolin group). The effect of the prophylactic antibiotic on the bacterial colonization of drains (mean duration of drainage: 3.2 +/- 0.3 days) and on the susceptibility of colonizing organisms was assessed. No significant difference was observed in the percentage of infected drains between the two groups. The cefamandole group had a lower rate of Gram-negative organisms (23% versus 44%, p less than 0.01). The rate of deep infections within one year after operation was 0.7% in the cefamandole group versus 0.5% in the cephazolin group, and the difference is not significant. Cefamandole given for two days appears to be an effective prophylaxis against sepsis in total hip replacements.

Disposition kinetics of cefamandole during continuous ambulatory peritoneal dialysis

Cefamandole disposition kinetics were examined in six male subjects with renal impairment who were undergoing continuous ambulatory peritoneal dialysis. Creatinine clearance values ranged from less than 1 to 11 ml/min. Cefamandole was given as a 1-g intravenous dose infused over 30 min. Cefamandole concentrations were determined in serum, urine, and dialysis fluid by a high-performance liquid chromatographic method. The following average parameter values were obtained (range): half-life, 6.1 h (4.6 to 9.7); systemic clearance, 21.9 ml/min (8.4 to 35.5); renal clearance, 11.5 ml/min (0.03 to 22.3); dialysis clearance, 0.92 ml/min (0.7 to 1.3); nonrenal clearance, 12.2 ml/min (2.9 to 27.0); volume of distribution, 0.18 liter/kg (0.09 to 0.25); steady-state volume of distribution, 0.17 liter/kg (0.09 to 0.24). Approximately 5% of the dose was dialyzed (range, 2.8 to 8.3), indicating that there is no need to supplement a dosing regimen of cefamandole due to loss by dialysis. There was a positive correlation between creatinine clearance and the terminal elimination rate constant of cefamandole (r2 = 0.41) and cefamandole renal clearance (r2 = 0.83).

Comparative in vitro study in new cephalosporins

Three new cephalosporins, ceftazidime, ceftizoxime, and cefotiam, were evaluated in vitro against clinical isolates, and their activities were compared with those of other cephalosporins, mezlocillin, and tobramycin. All three new cephalosporins were very active against gram-positive cocci (except enterococci), but mezlocillin was more active against Streptococcus ssp. Cefotiam and cefamandole were the most active antibiotics against Streptococcus aureus. Ceftazidime had broad-spectrum activity against all gram-negative bacilli tested, except Enterobacter spp. Ceftizoxime was active against all, except Enterobacter spp. and Pseudomonas aeruginosa. Although cefotiam was quite active against Escherichia coli, Klebsiella pneumoniae, and Proteus mirabilis, it was inactive against indole-positive Proteus spp., Serratia spp, and P. aeruginosa. The in vitro activity suggests that ceftazidime should prove useful as a broad-spectrum antibiotic, in those settings in which the most likely pathogens are gram-negative bacilli.

Evaluation of cefamandole susceptibility testing of Enterobacteriacea by the autobac 1 system

A total of 509 clinical isolates of Enterobacteriaceae were tested for susceptibility to cefamandole by Autobac 1 and Bauer-Kirby disk diffusion methods, using commercially available 30-micrograms cefamandole disks. Minimal inhibitory concentrations were determined for all organisms showing major or very major discrepancies. Overall agreement between Autobac 1 and disk diffusion was 89.8%, with 5.1% major or very major and 5.1% minor discrepancies. When considering only the genera for which 20 or more isolates were tested, overall agreement was 90.8%. Discrepancies for Escherichia coli showed a trend toward resistance by Autobac 1, with minimal inhibitory concentrations generally in agreement with disk diffusion results. No trends were detected for other genera. The rate of agreement was lower for Enterobacter species (75.4%), but minimal inhibitory concentrations, determined for all discrepancies in this genus, agreed with Autobafc 1 as often a with disk diffusion results.

The cephalosporins: activity and clinical use

The cephalosporin antibiotics have been employed with increasing frequency since their introduction into clinical practice in the early 1960s. With the exception of cephaloridine, cephalosporin compounds are not associated with the production of significant untoward effects. The availability of newer cephalosporins, both oral and parenteral, with enhanced antibacterial activity, has expanded the clinical indications for administration of these antibiotics.

A randomized study of carbenicillin plus cefamandole or tobramycin in the treatment of febrile episodes in cancer patients

Patients were randomly assigned to receive carbenicillin plus tobramycin by continuous infusion (C+T), carbenicillin plus cefamandole by continuous infusion (C+CC) or carbenicillin plus cefamandole by intermittent infusion (C+IC) during 490 febrile episodes. Carbenicillin was administered over 2 hours every 4 hours. The per cent of cures achieved during the 235 documented infections was 65 per cent for C+CC, 57 per cent for C+IC and 54 per cent for C+T. Among those infections caused by single gram-negative bacilli, C+CC produced a higher cure rate than C+IC or C+T(74 per cent versus 59 per cent versus 50 per cent). C+CC was significantly more effective than C+IC among patients with persistent severe neutropenia of less than 100 neutrophils/mm3 (65 per cent versus 21 per cent, p = 0.03). If the infecting organism was sensitive to both antibiotics, the cure rate which occurred during 12 per cent to 13 per cent of the febrile episodes, regardless of antibiotic regimen. However, it occurred significantly more often during documented infections than during fevers of unknown etiology (20 per cent versus 6 per cent, p less than 0.001). C+CC appears to be the most effective of the three regimens for the treatment of infections in patients with persistent severe neutropenia.

BL-S786 (ceforanide), a new parenteral cephalosporin: in vitro studies

BL-S786 (ceforanide) is a new cephalosporin which showed broad-spectrum activity in vitro against 453 clinical isolates. At a concentration of 3.12 mug/ml, it inhibited greater than 75% of isolates of Escherichia coli, Klebsiella spp., Proteus mirabilis, Staphylococcus aureus, Streptococcus pyogenes, and Streptococcus pneumoniae. Essentially no activity was observed against isolates of Serratia marcescens, and only minimal activity was observed against Enterobacter spp. Its activity was directly related to the size of the inoculum. The minimal bactericidal concentrations were similar to the minimal inhibitory concentrations for isolates of all organisms except S. aureus and S. pyogenes. The minimal bactericidal concentrations were considerably higher than the minimal inhibitory concentrations for these organisms.

Lack of correlation between beta-lactamase production and susceptibility to cefamandole or cefoxitin among spontaneous mutants of Enterobacteriaceae

A large number of cultures of gram-negative bacteria were examined for their susceptibility to various concentrations of cefamandole, cefoxitin, carbenicillin, and nalidixic acid. Heterogeneity of susceptibility was demonstrated in individual cultures to all of these antibiotics. Resistant clones isolated from cefamandole or cefoxitin plates were examined for beta-lactamase production. Approximately 13% of 262 resistant clones acquired the ability to produce a beta-lactamase. Examination of the substrate profile of the beta-lactamases from some of these clones revealed no change in the specific activity of these enzymes for cefamandole, cephaloridine, or compound 87/312 as compared with their parental enzymes. This study clearly shows that some resistant clones do not produce beta-lactamases, whereas some susceptible strains produced significant amounts of these enzymes. We conclude from these findings that little correlation exists between beta-lactamase production and decreased susceptibility to cefamandole or cefoxitin. The results suggest the possibility that characteristics other than beta-lactamase production may be responsible for resistance in Enterobacteriaceae.

Cefamandole levels in primary aqueous humor in man

We administered cefamandole nafate to 69 patients before cataract extraction and assayed serum and aqueous humor for antibiotic content at the time of surgery. Average aqueous humor levels of 0.33, 0.59, 0.21, and 0.14 microgram/ml were achieved at one half, one, two and four hours, respectively, after a 1-g intravenous dose. After a 2-g intravenous dose, we found average aqueous humor levels of 1.26, 1.0, 1.57, 0.73, and 0.34 microgram/ml at one half, one, two, four and six hours, respectively. Therapeutic levels in primary aqueous humor effective against common grampositive pathogens were consistently achieved with the 2-g dose, but levels effective against Enterobactereaceae were attained only erratically.

Beta lactamase resistance of newer cephalosporins and antimicrobial effectiveness against gram-negative bacilli

Three newer cephalosporins (cefamandole, cefoxitin and cefazaflur) were investigated, in comparison with three older agents (cephalothin, cephaloridine and cefazolin) to determine their stability to beta-lactamases of gram-negative bacilli, and to correlate this with their antibacterial activity. Nine of the 17 bacterial strains employed produced broadspectrum beta-lactamases; the remaining eight produced cephalosporinases. The cephalosporins were highly active against bacteria producing broad-spectrum beta-lactamases; they were less active against organisms producing cephalosporinases. All of the cephalosporinase-producing strains were resistant to cephalothin anc cephaloridine. With the other cephalosporins the correlation between hydrolysis by cephalosporinases and resistance of the organisms was poor. Four to eight cephalosporinase-producing strains were resistant to cefoxitin, which was completely resistant to hydrolysis by the beta-lactamases. Cefozolin, cefamandole and cefazaflur inhibited several of these strains in spite of destruction by the beta-lactamase. Several cephalosporins need to be used in antimicrobial susceptibility testing of gram-negative bacilli.

In vitro synergy of cefamandole-tobramycin combinations

Twenty-five isolates of Staphylococcus aureus, 24 isolates of Escherichia coli, and 25 isolates of Klebsiella pneumoniae obtained from clinical material were tested in vitro for susceptibility to cefamandole, tobramycin and combinations of the two antibiotics utilizing an automated microdilution system. Synergistic or partially synergistic bactericidal effects of the combination were observed against 15 of the S. aureus isolates (60%), 23 of the E. coli isolates (96%), and 19 of the K. pneumoniae isolates (76%) tested. No antagonistic effects of the combination were noted. This study suggests that cefamandole-tobramycin combinations are capable of acting synergistically in vitro against certain gram-positive and gram-negative organisms and may have potential usefulness in clinical situations such as gram-negative rod and staphylococcal sepsis.

Cefoxitin activity against multiply antibiotic-resistance Klebsiella pneumoniae in vitro

Due to the emergence of cephalothin- and gentamicin-resistant Klebsiella pneumoniae at this institution, we investigated the in vitro activity of two new cephalosporin compounds-cefoxitin and cefamandole. Whereas both drugs were active against cephalothin- and gentamicin-susceptible isolates of Klebsiella, only cefoxitin exhibited significant activity against cephalothin- and gentamicin-resistant isolates. Seventeen of 20 (85%) of the cephalothin- and gentamicin-resistant isolates were inhibited by </=12.5 mug of cefoxitin per ml. The minimum bactericidal concentration in broth of representative isolates equaled the agar dilution minimum inhibitory concentration. Kirby-Bauer disk susceptibility testing correlated well with the agar dilution minimum inhibitory concentration. Cephalothin and cefamandole resistance of isolates could be correlated with antibiotic degradation by beta-lactamase. Cephalothin and cefamandole evoked only a transient decrease in viable bacterial cell count with rapid inactivation of antibiotics, and full regrowth of the organisms. Cefoxitin, on the other hand, was quite effective in vitro against multiply resistant Klebsiella. No beta-lactamase degradation of cefoxitin was detected. Growth curves with antibiotics indicated rapid killing of cephalothin- and gentamicin-resistant isolates by cefoxitin.

Concentration of cefamandole in serum interstitial fluid, bile, and urine

Cefamandole readily diffuses from the serum into soft tissue interstitial fluid. The rate of diffusion differs little from that of cephalothin. The concentrations of antibiotic were greater in bile and urine during the entire period of study than is necessary to kill susceptible pathogenic bacteria present in these fluids.

Susceptibility of anaerobic bacteria to 23 antimicrobial agents

The antimicrobial susceptibility of 492 anaerobic bacteria, the majority of which were recent clinical isolates, was determined by the agar dilution technique. Penicillin G was active against most of the strains tested at 32 U or less/ml, but only 72% of Bacteroides fragilis strains were susceptible at this level and 9% required 256 U or more/ml. Ampicillin was effective against most of the strains except B. fragilis at 16 mug or less/ml. Amoxicillin was active against only 31% of B. fragilis, 76% of other Bacteroides species, and 67% of Fusobacterium species at 8 mug/ml. Two new penicillins, mezlocillin and azlocillin, were similar to ampicillin in their activity. Carbenicillin and ticarcillin inhibited all but a few strains at 128 mug or less/ml. BLP 1654 was somewhat more active than penicillin G against B. fragilis but had similar activity against other anaerobes. Cephalothin was inactive against B. fragilis, and only 65% of other Bacteroides species were inhibited by 32 mug or less/ml. It was effective against all other anaerobes at that level. Cefamandole showed somewhat greater activity than cephalothin against B. fragilis but generally less activity against gram-positive organisms. Cefazaflur (SKF 59962) was comparable to cephalothin against B. fragilis. Cefoxitin was distinctly more active than cephalothin against B. fragilis. These latter two agents were less active than cephalothin against the gram-positive anaerobes. Chloramphenicol remains active against anaerobic bacteria at 16 mug or less/ml, with rare exceptions. Thiamphenicol was similar to chloramphenicol in its activity. Clindamycin was very active against most of the anaerobes at 8 mug or less/ml. Erythromycin and josamycin were also tested, with josamycin showing greater activity against B. fragilis than either erythromycin or clindamycin. A new oligosaccharide, everninomicin B, was less active than clindamycin against B. fragilis but more active against clostridia and some of the other strains tested. Most of the groups of bacteria tested demonstrated a trend toward resistance to tetracycline. Doxycycline and minocycline were somewhat more active than was tetracycline. Metronidazole was active against the majority of the anaerobes tested; resistance ws demonstrated by some of the gram-positive cocci and gram-positive, non-sporeforming bacilli.

Comparison of the antibacterial activity of nine cephalosporins against Enterobacteriaceae and nonfermentative gram-negative bacilli

The in vitro antibacterial activity of nine cephalosporins (cephalothin, cephaloridine, cephalexin, cefazolin, cefamandole, cefuroxime, cefatrizine, cefoxitin, and cefazaflur) was determined against 344 strains of Enterobacteriaceae and 99 nonfermentative gram-negative bacilli. Cefamandole, cefazaflur, and cefuroxime were the most active cephalosporins against the Enterobacteriaceae (with the exception of Serratia marcescens). However, cefoxitin was the only cephalosporin that inhibited all 30 S. marcescens strains in a concentration of 16 mug/ml and was by far the most active compound against selected cephalothin-resistant strains of Escherichia coli, Klebsiella, and Proteus mirabilis. Acinetobacter spp. were inhibited best by cefuroxime, but none of the cephalosporins had appreciable activity against the Pseudomonas spp.