In vitro activity of HR 810, a new broad-spectrum cephalosporin

The Chemical Relationship Among Beta-Lactam Antibiotics and Potential Impacts on Reactivity and Decomposition

Beta-lactam antibiotics remain one of the most commonly prescribed drug classes, but they are limited by their propensity to cause hypersensitivity reactions (e.g., from allergy to anaphylaxis) as well as by the emergence of bacteria with a myriad of resistance mechanisms such as β-lactamases. While development efforts continue to focus on overcoming resistance, there are ongoing concerns regarding cross-contamination of β-lactams during manufacturing and compounding of these drugs. Additionally, there is a need to reduce levels of drugs such as β-lactam antibiotics in waste-water to mitigate the risk of environmental exposure. To help address future development of effective remediation chemistries and processes, it is desired to better understand the structural relationship among the most common β-lactams. This study includes the creation of a class-wide structural ordering of the entire β-lactam series, including both United States Food and Drug Association (US-FDA)-approved drugs and experimental therapies. The result is a structural relational map: the "Lactamome," which positions each substance according to architecture and chemical end-group. We utilized a novel method to compare the structural relationships of β-lactam antibiotics among the radial cladogram and describe the positioning with respect to efficacy, resistance to hydrolysis, reported hypersensitivity, and Woodward height. The resulting classification scheme may help with the development of broad-spectrum treatments that reduce the risk of occupational exposure and negative environmental impacts, assist practitioners with avoiding adverse patient reactions, and help direct future drug research.

Clinical study of cefpirome sulphate in obstetric and gynaecological infections

Cefpirome sulphate is a fourth-generation cephem antibiotic, which has a broad spectrum of antibacterial activity against Gram-positive and -negative bacteria, and is highly stable to beta-lactamase. Cefpirome sulphate was administered to 166 patients with obstetric or gynaecological infections, and its clinical and antibacterial effect was evaluable in 139. Excluding seven patients who violated the study protocol by receiving concomitant drugs, the safety of cefpirome sulphate was assessed in 159 patients. In the 139 patients in whom efficacy was evaluated, the improvement rate was 80.6% (112/139) and the eradication rate 72.6% (45/62). The eradication rate for bacteria isolated from the patients at the start of the study was 84.7% (111/131). No resistance to cefpirome sulphate was observed in Enterococcus faecalis or Bacteroides species. Systemic erythema and nausea each occurred in one patient, and nine patients showed abnormal hepatic function test results. These results suggest that cefpirome sulphate is effective in the treatment of obstetric and gynaecological infections and has a good side-effect profile.

Comparative study of pharmacokinetics and serum bactericidal activities of cefpirome, ceftazidime, ceftriaxone, imipenem, and ciprofloxacin

We compared the pharmacokinetics and the serum bactericidal activities of cefpirome, ceftazidime, ceftriaxone, imipenem, and ciprofloxacin. Fifteen healthy volunteers received 1 g of cefpirome, ceftazidime, and ceftriaxone intravenously, 500 mg of imipenem-cilastatin intravenously, and 500 mg of ciprofloxacin orally. High-performance liquid chromatographic assays were used to quantitate unchanged antibiotic in plasma and urine. Serum bactericidal activities were determined against six clinical isolates each of Staphylococcus aureus, Enterobacter cloacae, and Pseudomonas aeruginosa by using a modified microdilution method of Reller and Stratton (L. B. Reller and C. W. Stratton, J. Infect. Dis. 136:196-204, 1977). Overall, cefpirome exhibited pharmacokinetics similar to those of ceftazidime: half-life (t1/2), 1.95 h; concentration at 1 h (C1h), 47 to 49 micrograms/ml for both antibiotics. Ceftriaxone displayed the longest t1/2 (7.65 h) and the highest C1h (137.8 micrograms/ml), while we observed the shortest t1/2 (1.05 h) and the lowest C1h (19.85 micrograms/ml) with imipenem. At 1 h, cefpirome and, even more so, imipenem showed significantly better serum bactericidal activities against S. aureus (1:273 and 1:80) than did the other antibiotics (P less than 0.0005; analysis of variance with randomized block design and Bonferroni correction). Against E. cloacae, we observed the highest serum bactericidal titers at 1 h with cefpirome, and this superiority vis-à-vis the other antibiotics tested was maintained for up to 8 h after dosing. Ceftazidime remained the most active agent tested against P. aeruginosa (serum bactericidal activity titers, 1:43 at 1 h) up to 8 h. In summary, the study showed that cefpirome and imipenem provide more potent serum bactericidal activities than do broad-spectrum cephalosporins against S. aureus; thus, both of these antibiotics should be adequate against serious S. aureus infections. In addition, cefpirome appears to be a promising alternative for treatment of infections caused by E. cloacae and P. aeruginosa.

Single- and multiple-dose pharmacokinetics of intravenous cefpirome (HR810) to healthy volunteers

The safety and pharmacokinetics of single and multiple administrations of cefpirome (HR810), a new cephalosporin antibiotic agent with a broad antibacterial spectrum, were studied in healthy male volunteers. The single administration protocols included a 3-minute intravenous injection of 0.5 g or 1 g, and a 1-hour intravenous drip infusion of 0.5 g, 1 g, or 2 g. The multiple administration protocols included nine intravenous injections and 1-hour intravenous drip infusions of 1 g of cefpirome twice a day at intervals of 12 hours. Cefpirome was tolerated, and only a few mild, subjective and hepatic-function side effects were observed. There were no severe abnormalities. The drug concentrations in the plasma and the urine were determined by means of HPLC and bioassay, and the results correlated well (r = 0.99). The pharmacokinetic parameters were calculated using a two-compartment model. The elimination half-life (t1/2 beta) was about 1.7 hours for both intravenous injection and intravenous drip infusion and was not dose-dependent. AUC and Cmax were dose-dependent in this study, although an accumulation due to multiple administrations was not observed, and there were no changes in the pharmacokinetic parameters after the initial and the final administrations. The recovery rate of the unchanged compound in the urine was more than 80% in the 24 hours after a single administration and was the same after multiple administrations. Bioautography did not show any active metabolites in the plasma or the urine. The results, for safety and pharmacokinetics, show that cefpirome can be expected to have excellent clinical efficacy for bacterial infections.

Antimicrobial spectrum of cefpirome combined with tazobactam against the Bacteroides fragilis group

Cefpirome, a so-called fourth-generation cephalosporin, was tested alone and in combination with the sulfone beta-lactamase inhibitor, tazobactam, against 63 members of the Bacteroides fragilis group. The cefpirome MIC50 was only 64 micrograms/ml, but the MIC was reduced eightfold with tazobactam (2:1 ratio). The addition of tazobactam to cefpirome or the use of metronidazole as a codrug appear to be alternative choices to enhance the antianaerobic spectrum. Over 98% of strains had cefpirome-tazobactam MICs of less than or equal to 32 micrograms/ml.

In vitro antibacterial activity and beta-lactamase stability of the new carbapenem LJC10,627

In in vitro susceptibility tests the new carbapenem LJC10,627 showed potent antibacterial activity against gram-positive and gram-negative bacteria, except that most methicillin-resistant Staphylococcus aureus strains tested were found to be resistant to LJC10,627. LJC10,627 showed high activity against Pseudomonas aeruginosa and was active against Enterobacter cloacae and Citrobacter freundii strains which were resistant to ceftazidime and cefpirome. The Ki values of LJC10,627 for penicillinase Type I, cephalosporinase and oxyiminocephalosporinase were low, whereas the Ki value for L-1 enzyme from Xanthomonas maltophilia was high.

Interaction of cefpirome and a cephalosporinase from Citrobacter freundii GN7391

The interaction of cefpirome and a cephalosporinase from Citrobacter freundii, including hydrolysis and inhibition, was studied in comparison with those of cefotiam, cefotaxime, and ceftazidime. Cefpirome was hydrolyzed by the enzyme more rapidly at Vmax than were cefotaxime and ceftazidime. However, the low affinity of the enzyme for cefpirome caused a reduction in the hydrolytic rate of cefpirome at a low drug concentration (0.1 microM). The high stability of cefpirome at a low concentration explains the high antimicrobial activity of the agent against cephalosporinase-producing bacteria.

Beta-lactamase stability of cefpirome (HR 810), a new cephalosporin with a broad antimicrobial spectrum

Cefpirome was highly stable to hydrolysis by various beta-lactamases, although it was hydrolyzed to some extent by R plasmid-mediated penicillinase of Richmond-Sykes type Va/b and by chromosomal cephalosporinases from Bacteroides species. The compound had a very low affinity for cephalosporinases from Enterobacter cloacae, Citrobacter freundii, Serratia marcescens, and Proteus vulgaris. Cefpirome showed strong antimicrobial activity against eight beta-lactamase (cephalosporinase)-producing strains which have become resistant to broad-spectrum cephalosporins; especially against E. cloacae and C. freundii, it had the highest activity among the cephalosporins used. Its activity against ampicillin-resistant R plasmid-containing transconjugant isolates of Escherichia coli was as high as that against the recipient strain E. coli chi 1037. The inducer activity of cefpirome in S. marcescens and P. vulgaris increased dose dependently, whereas cephamycin derivatives showed high inducer activity at low concentrations. A relatively low affinity of cefpirome for beta-lactamases is considered to be one of the reasons for its high antimicrobial activity against such enzyme-producing strains. In addition, other factors such as good penetration through the outer membrane and affinity for the target sites may also be involved in the high activity of cefpirome.

The in vitro activity and beta-lactamase stability of cefpirome (HR 810), a pyridine cephalosporin agent active against staphylococci, Enterobacteriaceae and Pseudomonas aeruginosa

The in vitro activity of cefpirome, a new cyclopyridinium cephalosporin, was evaluated against 947 aerobic and anaerobic bacteria. Cefpirome inhibited 90% of Escherichia coli, Klebsiella spp., Citrobacter diversus, Morganella morganii, Proteus vulgaris, Proteus mirabilis, Aeromonas spp., Salmonella spp., Shigella spp. and Haemophilus and Neisseria species at less than or equal to 0.4 mg/l. It had activity comparable to that of cefotaxime, ceftizoxime, ceftazidime, aztreonam, and moxalactam against these species. Only a few Citrobacter freundii, Enterobacter spp. and Serratia marcescens had MICs above 3.1 mg/l. The activity of cefpirome against Pseudomonas aeruginosa, 90% MIC of 12.5 mg/l, was superior to piperacillin, moxalactam, cefotaxime and cefoperazone. The 90% MIC against Staphylococcus aureus was 0.8 mg/l, but methicillin-resistant staphylococci were not inhibited. Cefpirome was not significantly hydrolyzed by most plasmid beta-lactamases (TEM, SHV-1, PSE, OXA) nor by chromosomal enzymes (P99, Branhamella catarrhalis, K1). Cefpirome did not inhibit chromosomal or plasmid beta-lactamases. Mice systemically infected with E. coli, Klebsiella pneumoniae, P. aeruginosa and S. aureus were protected by concentrations of cefpirome ranging from 0.85 mg/kg for K. pneumoniae to 4.467 mg/kg for P. aeruginosa.

Anti-pseudomonal activity of HR 810

The anti-pseudomonal activity of HR 810, a new 2-aminothiazolyl cephalosporin, was compared to that of carbenicillin, azlocillin and cefsulodin against 187 non-fermenters. HR 810 was the best agent against Pseudomonas aeruginosa, Pseudomonas putida, Pseudomonas fluorescens and Acinetobacter calcoaceticus with an MIC50 less than or equal to 4 mg/l and an MIC90 less than or equal to 16 mg/l. It was as effective as azlocillin against Pseudomonas stutzeri and Pseudomonas mendocina, with an MIC50 less than or equal to 0.25 mg/l and an MIC90 less than or equal to 1 mg/l. It was not active against other species of Pseudomonas or other non-fermenters such as Flavobacterium sp.

Antimicrobial activity of HR810 against 419 strict anaerobic bacteria

HR810 and four other new beta-lactams were tested against 419 recent clinical anaerobic bacterial isolates. HR810 was found to have an antimicrobial spectrum most similar to that of cefotaxime, inhibiting 52.6% of Bacteroides fragilis group strains and 97.2% of all other anaerobic strains at an MIC of less than or equal to 16 micrograms/ml. Cefoxitin was found to have a narrower antimicrobial spectrum against the gram-positive anaerobic bacteria (8.4 to 10.1% less) than HR810 and cefotaxime, respectively.

In vitro activity of CGP 31523A, a broad-spectrum cephalosporin, in comparison with those of other agents

The in vitro activity of CGP 31523A, a new aminothiazolyl cephalosporin, was compared with those of cefoxitin, cefuroxime, moxalactam, piperacillin, ciprofloxacin, and other beta-lactams, when appropriate, against 533 recent clinical isolates and known resistant strains of bacteria. The MICs of CGP 31523A required to inhibit 90% (MIC90S) of the members of the family Enterobacteriaceae, Neisseria gonorrhoeae, and Streptococcus pneumoniae were less than or equal to 0.25 micrograms/ml. Of Staphylococcus aureus (excluding methicillin-resistant strains) and Haemophilus influenzae, 90% were susceptible to 0.5 micrograms/ml. Pseudomonas aeruginosa and Lancefield group D streptococci were resistant to CGP 31523A (MIC90, greater than or equal to 128 micrograms/ml). The activity against Bacteroides fragilis was modest (MIC90, 32 micrograms/ml). The susceptibility of known beta-lactamase-producing strains suggested that CGP 31523A was resistant to many beta-lactamases (but not those of Bacteroides fragilis). The serum protein binding of CGP 31523A was about 73%. The primary target site of CGP 31523A in Escherichia coli appeared to be penicillin-binding protein 3.

Disk diffusion testing, quality control guidelines, and antimicrobial spectrum of HR810, a fourth-generation cephalosporin, in clinical microbiology laboratories

HR810 is a new, very broad-spectrum cephalosporin with significant activity against members of the family Enterobacteriaceae, pseudomonads, gram-positive cocci, and anaerobes that is generally greater than the third-generation cephalosporins (99.6% of 4,128 clinical facultative enteric isolates were inhibited by less than or equal to 8.0 micrograms of HR810 per ml). Tests and statistical methods to establish in vitro antimicrobial susceptibility test criteria favor tentative breakpoints of greater than or equal to 18 mm (less than or equal to 8.0 micrograms/ml) as susceptible and less than or equal to 14 mm (greater than or equal to 32 micrograms/ml) as resistant. This provides a 93.7 to 98.3% absolute interpretive accuracy. Several preliminary ranges for zone sizes obtained with quality control organisms are proposed for the 30-micrograms HR810 disk diffusion test used during the clinical trials.

In vitro activity of HR 810, a new cephalosporin

The in vitro susceptibility of 409 clinical isolates to HR 810, a new cephalosporin, was evaluated and compared with their susceptibility to aztreonam, cefazolin, ceftazidime, imipenem, moxalactam, piperacillin, and gentamicin. On a weight basis, the activity of HR 810 against gram-negative bacilli was equivalent or superior to that of the other beta-lactam agents except imipenem.

In vitro evaluation of HR810, a new wide-spectrum aminothiazolyl alpha-methoxyimino cephalosporin

HR810 (Hoechst-Roussel Pharmaceuticals Inc., Somerville, N.J.) is a new, cyclical-pyridinium cephalosporin that appeared superior to numerous comparison drugs against 658 strains of aerobic and facultative anaerobic bacteria. Seventeen Enterobacteriaceae spp. were tested by broth microdilution methods, and the 50% MICs (MIC50S) and 90% MICs (MIC90s) were 0.03 to 0.12 and 0.03 to 2.0 micrograms/ml, respectively. Only one strain had an MIC greater than 8.0 micrograms/ml (99.6% is considered susceptible). HR810 inhibited 98% of Pseudomonas aeruginosa isolates at less than or equal to 16 micrograms/ml, and the MIC90 for Acinetobacter spp. was 4.0 micrograms/ml. It was also very active against Pseudomonas spp. and Staphylococcus aureus (MIC90, 0.5 micrograms/ml) but marginally active against methicillin-resistant staphylococcal strains (MIC90, 16 micrograms/ml) and enterococcus (MIC90, 32 micrograms/ml). Non-enterococcal streptococci had MIC50s ranging from 0.008 micrograms/ml for Streptococcus pyogenes to 0.12 micrograms/ml for pneumococci. All MICs of HR810 against Haemophilus and Neisseria spp. were less than or equal to 0.03 micrograms/ml (MIC50, 0.002 to 0.008 micrograms/ml). HR810 poorly inhibited beta-lactamases and was very stable against 11 tested beta-lactamases of plasmid (TEM, OXA, SHV-1, and PSE) and chromosomal (K1, K14, P99) types.