ceftobiprole and Neutropenia

Ceftobiprole is a fifth generation cephalosporin with a series of characteristics differentiating it from other beta-lactams, including its antibacterial activity, mainly against methicillin-resistant Staphylococcus aureus, resistant Streptococcus pneumoniae and also Gram-negative microorganisms such as Pseudomonas aeruginosa. This antibiotic has been subjected to various clinical trials and the results of these have led to its approval in Spain for the treatment of nosocomial pneumonia, excluding that associated with mechanical ventilation, and community-acquired pneumonia. The results of various ceftobiprole clinical studies provide consistent information on efficacy and tolerability. Ceftobiprole as monotherapy has been shown to be non-inferior to comparator antibiotics in different settings. Information is available on its compatibility with other drugs in Y-site administration, important from the point of view of the intravenous treatment of patients who present venous access limitation. On the other hand, and in contrast to other cephalosporins, ceftobiprole presents a low risk of infection due to Clostridium difficile and, in comparison with ceftaroline, neutropenia has not been reported to present any significant issues.

Topics: Administration, Intravenous; Anti-Bacterial Agents; Cephalosporins; Clinical Trials, Phase I as Topic; Clinical Trials, Phase III as Topic; Community-Acquired Infections; Cross Infection; Humans; Methicillin-Resistant Staphylococcus aureus; Neutropenia; Pneumonia, Bacterial; Pseudomonas aeruginosa; Streptococcus pneumoniae

Reduced bactericidal efficacy at a high inoculum is known as the inoculum effect (IE). We used neutropenic mice to compare the IEs of ceftobiprole (CFB), daptomycin (DAP), linezolid (LZD), and vancomycin (VAN) against 6 to 9 strains of Staphylococcus aureus and 4 strains of Streptococcus pneumoniae at 2 inocula in opposite thighs of the same mice. Neutropenic mice had 10(4.5) to 10(5.7) CFU/thigh (low inoculum [LI]) in one thigh and 10(6.4) to 10(7.2) CFU/thigh (high inoculum [HI]) in the opposite thigh when treated for 24 h with subcutaneous (s.c.) doses every 12 h of DAP at 0.024 to 100 mg/kg of body weight and LZD at 0.313 to 320 mg/kg and s.c. doses every 6 h of CFB at 0.003 to 160 mg/kg and VAN at 0.049 to 800 mg/kg. Dose-response data were analyzed by a maximum effect (E(max)) model using nonlinear regression. Static doses for each drug and at each inoculum were calculated, and the difference between HI and LI (IE index) gave the magnitude of IE for each drug-organism combination. Mean (range) IE indexes of S. aureus were 2.9 (1.7 to 4.6) for CFB, 4.1 (2.6 to 9.3) for DAP, 4.6 (1.7 to 7.1) for LZD, and 10.1 (6.3 to 20.3) for VAN. In S. pneumoniae, the IE indexes were 2.5 (1.3 to 3.3) for CFB, 2.0 (1.6 to 2.8) for DAP, 1.9 (1.7 to 2.2) for LZD, and 1.5 (0.8 to 3.2) for VAN; these values were similar for all drugs. In S. aureus, the IE was much larger with VAN than with CFB, DAM, and LZD (P < 0.05). An in vivo time course of vancomycin activity showed initiation of killing at 4- to 16-fold-higher doses at HI than at LI despite similar initial growth of controls.

Topics: Acetamides; Animals; Anti-Bacterial Agents; Cephalosporins; Colony Count, Microbial; Daptomycin; Dose-Response Relationship, Drug; Drug Administration Schedule; Female; Injections, Subcutaneous; Linezolid; Mice; Mice, Inbred ICR; Microbial Sensitivity Tests; Neutropenia; Oxazolidinones; Pneumococcal Infections; Staphylococcal Infections; Staphylococcus aureus; Streptococcus pneumoniae; Thigh; Vancomycin

Ceftobiprole medocaril is the parenteral prodrug of ceftobiprole, a novel pyrrolidinone broad-spectrum cephalosporin with in vitro and in vivo bactericidal activities against methicillin-resistant Staphylococcus aureus (MRSA) and penicillin-resistant Streptococcus pneumoniae (PRSP). We have used murine thigh and lung infection models in neutropenic and normal mice to characterize the in vivo pharmacokinetic (PK)-pharmacodynamic (PD) activities of ceftobiprole against multiple strains of S. aureus (including MRSA), S. pneumoniae (including PRSP), and gram-negative bacilli. Serum levels of ceftobiprole following the administration of multiple doses were determined by a microbiological assay. In vivo bactericidal activities and postantibiotic effects (PAEs) of ceftobiprole against MRSA and PRSP strains were determined from serial CFU/thigh values following single doses of ceftobiprole (40 and 160 mg/kg of body weight). Dose fractionation studies were used to determine which PK-PD index correlated best with activity. Magnitudes of the PK-PD indices were calculated from MICs and PK parameters. A sigmoid dose-response model was used to estimate the dose (mg/kg/24 h) required to achieve a static and 2-log(10) kill effects over 24 h. PK results showed area under the concentration-time curve/dose values of 1.8 to 2.8 and half-lives of 0.29 to 0.51 h. MICs ranged from 0.015 to 2 microg/ml. Ceftobiprole demonstrated time-dependent killing; its in vivo PAEs varied from 3.8 h to 4.8 h for MRSA and from 0 to 0.8 h for PRSP. The time above MIC (T > MIC) correlated best with efficacy for both MRSA and PRSP. The T > MIC values required for the static doses were significantly longer (P < 0.001) for Enterobacteriaceae (36 to 45%) than for S. aureus (14 to 28%) and S. pneumoniae (15 to 22%). The drug showed activities in the lung model similar to those in the thigh model. The presence of neutrophils significantly enhanced the activity of ceftobiprole against S. pneumoniae but only slightly against Klebsiella pneumoniae. Based on its PD profile, ceftobiprole is a promising new beta-lactam agent with activity against gram-negative and gram-positive organisms including MRSA and PRSP.

Topics: Animals; Anti-Bacterial Agents; Bacterial Infections; Cephalosporin Resistance; Cephalosporins; Disease Models, Animal; Dose-Response Relationship, Drug; Enterobacteriaceae Infections; Extremities; Female; Gram-Negative Bacterial Infections; Lung Diseases; Methicillin Resistance; Mice; Mice, Inbred ICR; Neutropenia; Penicillin Resistance; Pneumococcal Infections; Staphylococcal Infections; Staphylococcus aureus