Fernando Acosta

Daptomycin Is Highly Efficacious against Penicillin-Resistant and Penicillin- and Quinolone-Resistant Pneumococci in Experimental Meningitis

ABSTRACT The penetration of daptomycin, a new lipopeptide antibiotic, into inflamed meninges ranged between 4.37 and 7.53% (mean, 5.97%). Daptomycin was very efficacious in the treatment of experimental pneumococcal meningitis, producing a decrease of −1.20 ± 0.32 Δlog10 CFU/ml · h in the bacterial titer of Streptococcus pneumoniae against a penicillin-resistant strain and of −0.97 ± 0.32 Δlog10 CFU/ml · h against a penicillin- and quinolone-resistant strain found in cerebrospinal fluid (CSF). For both strains, daptomycin was significantly superior to the standard regimen of a combination of ceftriaxone with vancomycin, sterilizing 9 of 10 CSF samples after 4 h. In vitro, daptomycin produced highly bactericidal activity in concentrations above the MIC.

Efficacy of Telavancin against Penicillin-Resistant Pneumococci and Staphylococcus aureus in a Rabbit Meningitis Model and Determination of Kinetic Parameters

ABSTRACT The penetration of telavancin was 2% into inflamed meninges and ca. 1‰ into noninflamed meninges after two intravenous injections (30 mg/kg of body weight). In experimental meningitis, telavancin was significantly superior to vancomycin combined with ceftriaxone against a penicillin-resistant pneumococcal strain. Against a methicillin-sensitive staphylococcal strain, telavancin was slightly but not significantly superior to vancomycin.

Activities of Ertapenem, a New Long-Acting Carbapenem, against Penicillin-Sensitive or -Resistant Pneumococci in Experimental Meningitis

ABSTRACT The penetration of ertapenem, a new carbapenem with a long half-life, reached 7.1 and 2.4% into inflamed and noninflamed meninges, respectively. Ertapenem had excellent antibacterial activity in the treatment of experimental meningitis due to penicillin-sensitive and -resistant pneumococci, leading to a decrease of 0.69 ± 0.17 and 0.59 ± 0.22 log10 CFU/ml · h, respectively, in the viable cell counts in the cerebrospinal fluid. The efficacy of ertapenem was comparable to that of standard regimens (ceftriaxone monotherapy against the penicillin-sensitive strain and ceftriaxone combined with vancomycin against the penicillin-resistant strain). In vitro, ertapenem in concentrations above the MIC was highly bactericidal against both strains. Even against a penicillin- and quinolone-resistant mutant, ertapenem had similar bactericidal activity in vitro.

Synergy between Trovafloxacin and Ceftriaxone against Penicillin-Resistant Pneumococci in the Rabbit Meningitis Model and In Vitro

ABSTRACT The bactericidal activities of monotherapy with trovafloxacin (−0.37 ± 0.15 Δlog10 CFU/ml · h), vancomycin (−0.32 ± 0.12 Δlog10 CFU/ml · h), and ceftriaxone (−0.36 ± 0.19 Δlog10CFU/ml · h) for the treatment of experimental meningitis in rabbits due to a clinical penicillin-resistant pneumococcal strain (MIC, 4 mg/liter) were similar. The combination of ceftriaxone with trovafloxacin considerably improved the killing rates (−0.67 ± 0.16 Δlog10 CFU/ml · h) and was slightly superior to ceftriaxone with vancomycin (killing rate, −0.53 ± 0.22 Δlog10 CFU/ml · h), the regimen most commonly used in clinical practice. In vitro, synergy was demonstrated between ceftriaxone and trovafloxacin by the checkerboard method (fractional inhibitory concentration index, 0.5) and by time-killing assays over 8 h.

Cefotaxime Acts Synergistically with Levofloxacin in Experimental Meningitis Due to Penicillin-Resistant Pneumococci and Prevents Selection of Levofloxacin-Resistant Mutants In Vitro

ABSTRACT Cefotaxime, given in two doses (each 100 mg/kg of body weight), produced a good bactericidal activity (−0.47 Δlog10 CFU/ml · h) which was comparable to that of levofloxacin (−0.49 Δlog10 CFU/ml · h) against a penicillin-resistant pneumococcal strain WB4 in experimental meningitis. Cefotaxime combined with levofloxacin acted synergistically (−1.04 Δlog10 CFU/ml · h). Synergy between cefotaxime and levofloxacin was also demonstrated in vitro in time killing assays and with the checkerboard method for two penicillin-resistant strains (WB4 and KR4). Using in vitro cycling experiments, the addition of cefotaxime in sub-MIC concentrations (one-eighth of the MIC) drastically reduced levofloxacin-induced resistance in the same two strains (64-fold increase of the MIC of levofloxacin after 12 cycles versus 2-fold increase of the MIC of levofloxacin combined with cefotaxime). Mutations detected in the genes encoding topoisomerase IV (parC and parE) and gyrase (gyrA and gyrB) confirmed the levofloxacin-induced resistance in both strains. Addition of cefotaxime in low doses was able to suppress levofloxacin-induced resistance.

Gemifloxacin Is Efficacious against Penicillin-Resistant and Quinolone-Resistant Pneumococci in Experimental Meningitis

ABSTRACT In experimental rabbit meningitis, gemifloxacin penetrated inflamed meninges well (22 to 33%) and produced excellent bactericidal activity (change in log10 [Δlog10] CFU/ml/h, −0.68 ± 0.30 [mean and standard deviation]), even superior to that of the standard regimen of ceftriaxone plus vancomycin (−0.49 ± 0.09 Δlog10 CFU/ml/h), in the treatment of meningitis due to a penicillin-resistant pneumococcal strain (MIC, 4 mg/liter). Even against a penicillin- and quinolone-resistant strain, gemifloxacin showed good bactericidal activity (−0.48 ± 0.16 Δlog10 CFU/ml/h). The excellent antibacterial activity of gemifloxacin was also confirmed by time-kill assays over 8 h in vitro.

Efficacies of BMS 284756 against penicillin-sensitive, penicillin-resistant, and quinolone-resistant pneumococci in experimental meningitis

ABSTRACT BMS 284756 penetrated well into inflamed meninges (44% ± 11%) and produced good bactericidal activity (−0.82 ± 0.22 Δlog10 CFU/ml · h) in the treatment of experimental meningitis in rabbits due to a penicillin-sensitive strain. BMS 284756 monotherapy had a greater potency than the standard regimen of ceftriaxone and vancomycin (−0.49 ± 0.08 Δlog10 CFU/ml · h) against a penicillin-resistant strain (MIC, 4 mg/liter). Even against a penicillin- and quinolone-resistant strain, BMS 284756 showed good bactericidal activity (−0.52 ± 0.12 Δlog10 CFU/ml · h). The antibacterial activity of BMS 284756 was confirmed by time-killing assays over 8 h in vitro.

Effects of EDP-420 on penicillin-resistant and quinolone- and penicillin-resistant pneumococci in the rabbit meningitis model.

OBJECTIVES To test the efficacy of EDP-420, a new ketolide, in experimental pneumococcal meningitis and to determine its penetration into the CSF. METHODS The experimental rabbit model was used in this study and EDP-420 was tested against a penicillin-resistant and a penicillin- and quinolone-resistant mutant. EDP-420 was also tested against both strains in time-killing assays over 8 h in vitro. RESULTS In experimental meningitis, EDP-420 produced a bactericidal activity comparable to the standard regimen based on a combination of vancomycin with ceftriaxone against a penicillin-resistant Streptococcus pneumoniae and a penicillin- and quinolone-resistant S. pneumoniae isolate. The penetration of EDP-420 into inflamed meninges was 38% after an i.v. injection of 10 mg/kg. The bactericidal activity of EDP-420 was also confirmed in in vitro time-killing assays. CONCLUSIONS EDP-420 is an efficacious alternative treatment in pneumococcal meningitis, especially when resistant strains are suspected.

Evaluation of ceftobiprole activity against a variety of gram-negative pathogens, including Escherichia coli, Haemophilus influenzae (β-lactamase positive and β-lactamase negative), and Klebsiella pneumoniae, in a rabbit meningitis model.

ABSTRACT Ceftobiprole medocaril, a new cephalosporin, is highly active against a broad spectrum of Gram-positive and Gram-negative clinical pathogens, including methicillin-resistant Staphylococcus aureus (MRSA) and penicillin-resistant pneumococci. In this study, we tested ceftobiprole against various Gram-negative pathogens in a rabbit meningitis model and determined its penetration into the cerebrospinal fluid (CSF). In this animal model, ceftobiprole produced an antibacterial activity similar to that of cefepime against an Escherichia coli strain, a Klebsiella pneumoniae strain, and a β-lactamase-negative Haemophilus influenzae strain. Against a β-lactamase-positive H. influenzae strain, ceftobiprole was significantly superior. The penetration of ceftobiprole through inflamed meninges reached about 16% of serum levels compared to about 2% of serum levels through uninflamed meninges.

Efficacy of doripenem against Escherichia coli and Klebsiella pneumoniae in experimental meningitis

OBJECTIVES In this study the efficacy of doripenem, a new broad-spectrum carbapenem, was tested against an Escherichia coli strain and a Klebsiella pneumoniae strain in an experimental animal model. The comparator was cefepime monotherapy. METHODS The rabbit meningitis model was used in this study and the penetration of doripenem through uninflamed and inflamed meninges was determined. RESULTS Doripenem, injected three times (75 mg/kg), led to serum peak levels around 100 mg/L and trough levels around 5 mg/L, resulting in a penetration rate of 14% through inflamed meninges and 7% through uninflamed meninges. Against K. pneumoniae, doripenem was slightly but not significantly more efficacious than cefepime over 8 h (5.40 ± 1.37 log(10) cfu/mL versus 3.59 ± 0.89 log(10) cfu/mL for cefepime). Also against the E. coli strain doripenem was slightly superior to the comparator (5.55 ± 0.87 log(10) cfu/mL versus 3.80 ± 1.10 log(10) cfu/mL for cefepime), although the difference was not significant. CONCLUSIONS Doripenem is a potential monotherapy for the treatment of meningitis due to Gram-negative microorganisms.