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Biomedical subjects

P Cottagnoud

Publications and source records attributed to P Cottagnoud.

At least 37 records · Page 2Linked to original sources
PubMed2003

Vancomycin acts synergistically with gentamicin against penicillin-resistant pneumococci by increasing the intracellular penetration of gentamicin.

Vancomycin and gentamicin act synergistically against penicillin-resistant pneumococci in vitro and in experimental rabbit meningitis. The aim of the present study was to investigate the underlying mechanism of this synergism. The intracellular concentration of gentamicin was measured by using the following experimental setting. Bacterial cultures were incubated with either gentamicin alone or gentamicin plus vancomycin for a short period (15 min). The gentamicin concentration was determined before and after grinding of the cultures by using the COBAS INTEGRA fluorescence polarization system (Roche). The grinding efficacies ranged between 44 and 54%, as determined by viable cell counts. In the combination regimen the intracellular concentration of gentamicin increased to 186% compared to that achieved with gentamicin monotherapy. These data suggest that the synergy observed in vivo and in vitro is based on an increased intracellular penetration of the aminoglycoside, probably due to the effect of vancomycin on the permeability of the cell wall.

Animals↗
PubMed2003

Activities of ertapenem, a new long-acting carbapenem, against penicillin-sensitive or -resistant pneumococci in experimental meningitis.

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 log(10) CFU/ml x 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.

Animals↗
PubMed2003

Cefotaxime acts synergistically with levofloxacin in experimental meningitis due to penicillin-resistant pneumococci and prevents selection of levofloxacin-resistant mutants in vitro.

Cefotaxime, given in two doses (each 100 mg/kg of body weight), produced a good bactericidal activity (-0.47 Deltalog(10) CFU/ml. h) which was comparable to that of levofloxacin (-0.49 Deltalog(10) CFU/ml. h) against a penicillin-resistant pneumococcal strain WB4 in experimental meningitis. Cefotaxime combined with levofloxacin acted synergistically (-1.04 Deltalog(10) 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.

Animals↗
PubMed2003

The stereochemistry of the amino acid side chain influences the inflammatory potential of muramyl dipeptide in experimental meningitis.

Intrathecal injections of 50 to 100 micro g of (N-acetylmuramyl-L-alanyl-D-isoglutamine) muramyl dipeptide (MDP)/rabbit dose-dependently triggered tumor necrosis factor alpha (TNF-alpha) secretion (12 to 40,000 pg/ml) preceding the influx of leukocytes in the subarachnoid space of rabbits. Intrathecal instillation of heat-killed unencapsulated R6 pneumococci produced a comparable leukocyte influx but only a minimal level of preceding TNF-alpha secretion. The stereochemistry of the first amino acid (L-alanine) of the MDP played a crucial role with regard to its inflammatory potential. Isomers harboring D-alanine in first position did not induce TNF-alpha secretion and influx of leukocytes. This stereospecificity of MDPs was also confirmed by measuring TNF-alpha release from human peripheral mononuclear blood cells stimulated in vitro. These data show that the inflammatory potential of MDPs depends on the stereochemistry of the first amino acid of the peptide side chain and suggest that intact pneumococci and MDPs induce inflammation by different pathways.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed2002

Reactive macrophage activation syndrome: a simple screening strategy and its potential in early treatment initiation.

QUESTIONS UNDER STUDY: starting treatment of reactive macrophage activation syndromes as early as possible (rMAS, haemophagocytic lymphohistiocytosis), e.g., with intravenous immunoglobulins (IVIG), seems to be essential for optimal outcome. However, there is no diagnostic gold standard which reliably indicates need for early treatment. We used a simple screening strategy consisting of serum ferritin measurements and/or morphological assessment of haemophagocytosis and compared the studied patient population with published series. METHODS: Retrospective analysis of clinical and laboratory data of 57 patients experiencing 60 episodes of rMAS. RESULTS: Screening by serum ferritin measurements and/or morphological assessment of haemophagocytosis of patients presenting with a systemic inflammatory response syndrome (SIRS) indicates that rMAS might be considerably more frequent than stated in the literature. Serum ferritin exceeded >10,000 microg/L in 91% rMAS episodes. Although the patient population studied was otherwise similar in most aspects to the published rMAS series, the fact that 40% of patients fulfilled the criteria for Still's disease (SD) as the disorder underlying rMAS is remarkable and questions the distinct nature of the two diseases. IVIG responders and non-responders did not differ regarding their initial characteristics with exception to the timepoint of IVIG administration, confirming the importance of early treatment initiation. Malignancy-associated rMAS however, has a poor prognosis and seems to be refractory to manipulation with IVIG in most instances, even when responding initially. CONCLUSIONS: rMAS has to be considered in patients with a SIRS- or SD-like clinical presentation. Hyperferritinaemia >or=10,000 microg/l seems to be a good marker for defining patients with or at risk for developing rMAS and should be completed with a morphological assessment of haemophagocytosis. The perception of acute SD and rMAS as two distinct entities has to be questioned at least in a subgroup of patients.

Adolescent↗
PubMed2002

Cellular and molecular aspects of drugs of the future: meropenem.

Meropenem, first synthesized in the late eighties, has become one of the most important beta-lactam antibiotics of the carbapenem subclass used for the treatment of a variety of life-threatening infections. Due to its unique chemical structure, meropenem is not inactivated by the kidney dehydropeptidase I and the majority of microbial beta-lactamases. Its antimicrobial activity is based on its high affinity for the majority of cell wall-synthesizing enzymes, the so-called penicillin-binding proteins, of Gram-positive and -negative bacteria. However, bacteria have evolved several approaches to resist meropenem: (i) by reducing the affinity of the penicillin-binding proteins for the antibiotics, (ii) by decreasing the permeability of the outer membrane of Gram-negative bacteria, (iii) by using efflux pumps, and (iv) by activating zinc-dependent carbapenemases. Meropenem has a low toxicity profile and, in contrast to imipenem, no central nervous system toxicity.

Animals↗
PubMed2001

Sub-inhibitory concentrations of vancomycin prevent quinolone-resistance in a penicillin-resistant isolate of Streptococcus pneumoniae.

BACKGROUND: The continuous spread of penicillin-resistant pneumococci represents a permanent threat in the treatment of pneumococcal infections, especially when strains show additional resistance to quinolones. The main objective of this study was to determine a treatment modality impeding the emergence of quinolone resistance. RESULTS: Exposure of a penicillin-resistant pneumococcus to increasing concentrations of trovafloxacin or ciprofloxacin selected for mutants resistant to these drugs. In the presence of sub-inhibitory concentrations of vancomycin, development of trovafloxacin-resistance and high-level ciprofloxacin-resistance were prevented. CONCLUSIONS: Considering the risk of quinolone-resistance in pneumococci, the observation might be of clinical importance.

4-Quinolones↗
PubMed2001

Hyperferritinemia as indicator for intravenous immunoglobulin treatment in reactive macrophage activation syndromes.

The underlying mechanisms of reactive macrophage activation syndromes (rMAS) are not understood in detail, and there is no specific treatment. This observational study was prompted by intravenous immunoglobulin (IVIG), dramatically halting two distinct rMAS episodes in the same patient. We evaluated the potential benefits of IVIG administration in treating fulminant rMAS and the usefulness of monitoring serum ferritin levels as an indication for emergency treatment with IVIG. Ten females and 10 males experiencing 22 episodes of rMAS were recruited on the basis of serum ferritin levels >or=10,000 microg/l and/or direct evidence of haemophagocytosis in 11 intensive care units in secondary and tertiary care hospitals in Switzerland between October 1993 and May 2000. In individual patients, serially measured ferritin was closely related to disease activity. Abrupt increases of up to >100,000 microg/l could be observed within hours. Rapid and profound beneficial effects of emergency IVIG treatment were seen in 12 episodes of rMAS accompanied by a prompt decrease of serum ferritin. IVIG produced partial or delayed improvements in 5 patients. No apparent effects were seen in 5 patients. IVIG was only successful if started early during the ferritin run-up to peak values. In conclusion, IVIG is effective in at least a subgroup of adult rMAS when started at the beginning of the macrophage activation process. The monitoring of serum ferritin levels might be helpful in detecting macrophage activation in order to commence IVIG treatment early enough.

Adolescent↗
PubMed2001

Efficacy of gatifloxacin alone and in combination with cefepime against penicillin-resistant Streptococcus pneumoniae in a rabbit meningitis model and in vitro.

Gatifloxacin penetrated well into cerebrospinal fluid (CSF) (49 +/- 11%), measured by comparison of AUC(CSF)/AUC(serum), and showed good bactericidal activity (leading to a decrease of 0.75 +/- 0.17 log10 cfu/mL/h) in the treatment of experimental meningitis in rabbits caused by a penicillin-resistant pneumococcal strain (MIC 4 mg/L). It was significantly more effective than the standard regimen, ceftriaxone with vancomycin, which led to a decrease of 0.53 +/- 0.17 log10 cfu/mL/h. The addition of cefepime to gatifloxacin slightly improved the killing rates (giving a decrease of 0.84 +/- 0.14 log10 cfu/mL/h). In vitro, synergy was demonstrated between cefepime and gatifloxacin by the chequerboard method (fractional inhibitory concentration index = 0.5) and by viable counts over 8 h.

Animals↗
PubMed2000

Evaluation of cefepime alone and in combination with vancomycin against penicillin-resistant pneumococci in the rabbit meningitis model and in vitro.

Cefepime, a broad-spectrum, fourth-generation cephalosporin, showed excellent CSF penetration with levels ranging between 10 and 16 mg/L after two intravenous injections (100 mg/kg). The bactericidal activity of cefepime (-0.60 +/- 0.28 Deltalog(10) cfu/mL/h) was superior to that of ceftriaxone (-0.34 +/- 0.23 Deltalog(10) cfu/mL/h, P < 0.05) and vancomycin (-0.39 +/- 0.19 Deltalog(10) cfu/mL/h, P < 0.05) in the treatment of rabbits with meningitis caused by an isolate highly resistant to penicillin (MIC of penicillin G: 4 mg/L). The addition of vancomycin to both cephalosporins did not significantly increase the killing rate compared with monotherapies (P > 0.05). Similar results were obtained in time-killing experiments in vitro.

Animals↗
PubMed2000

Grepafloxacin against penicillin-resistant pneumococci in the rabbit meningitis model.

Grepafloxacin, a new fluoroquinolone, produced bactericidal activity comparable to that of vancomycin and ceftriaxone in the treatment in rabbits of meningitis caused by a pneumococcal strain highly resistant to penicillin (MIC 4 mg/L) (triangle uplog(10) cfu/mL*h for grepafloxacin, -0.32 +/- 0.15; dose, 15 mg/kg iv; triangle uplog(10) cfu/mL*h for vancomycin, -0.39 +/- 0.18; dose, 2 x 20 mg/kg iv; triangle uplog(10) cfu/mL*h for ceftriaxone, -0.32 +/- 0. 12; dose, 125 mg/kg iv). Higher doses of grepafloxacin (30 mg/kg and 2 x 50 mg/kg) did not improve the killing rates. The combination of grepafloxacin with vancomycin was not significantly superior to monotherapies (P > 0.05). In vitro, grepafloxacin was bactericidal at concentrations above the MIC. Using concentrations around the MIC, addition of vancomycin to grepafloxacin showed synergic activity.

Animals↗
PubMed2000

Linezolid against penicillin-sensitive and -resistant pneumococci in the rabbit meningitis model.

Linezolid, a new oxazolidinone antibiotic, showed good penetration (38+/-4%) into the meninges of rabbits with levels in the CSF ranging from 9.5 to 1.8 mg/L after two i.v. injections (20 mg/kg). Linezolid was clearly less effective than ceftriaxone against a penicillin-sensitive pneumococcal strain. Against a penicillin-resistant strain, linezolid had slightly inferior killing rates compared with the standard regimen (ceftriaxone combined with vancomycin). In vitro, linezolid was marginally bactericidal at concentrations above the MIC (5 x and 10 x MIC).

Acetamides↗
PubMed2000

Synergy between trovafloxacin and ceftriaxone against penicillin-resistant pneumococci in the rabbit meningitis model and in vitro.

The bactericidal activities of monotherapy with trovafloxacin (-0.37 +/- 0.15 Delta log(10) CFU/ml. h), vancomycin (-0.32 +/- 0.12 Delta log(10) CFU/ml. h), and ceftriaxone (-0.36 +/- 0.19 Delta log(10) CFU/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 Delta log(10) CFU/ml. h) and was slightly superior to ceftriaxone with vancomycin (killing rate, -0.53 +/- 0. 22 Delta log(10) 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.

Animals↗
PubMed1999

Meropenem alone and in combination with vancomycin in experimental meningitis caused by a penicillin-resistant pneumococcal strain.

In a rabbit model of meningitis caused by a pneumococcus highly resistant to penicillin (MIC, 4 microg/ml), meropenem, a broad-spectrum carbapenem, was bactericidal (-0.48+/-0.14 deltalog10 cfu/ml h) and slightly superior to ceftriaxone (-0.34+/-0.23 deltalog10 cfu/ml x h) and vancomycin (-0.39+/-0.19 deltalog10 cfu/ml x h). Although the combination of vancomycin with ceftriaxone was significantly more active than ceftriaxone alone (-0.55+/-0.19 deltalog10 cfu/ml x h), only an insignificant gain was observed by the addition of vancomycin to meropenem (-0.55+/-0.28 deltalog10 cfu/ml x h).

Animals↗
PubMed1999

Trovafloxacin in combination with vancomycin against penicillin-resistant pneumococci in the rabbit meningitis model.

Trovafloxacin, a new fluoroquinolone, produced bactericidal activity (-0.33 +/- 0.13 delta log10 CFU/ml.h; intravenously [i.v.] administered dose, 15 mg/kg) comparable to that of vancomycin (-0.39 +/- 0.18 delta log10 CFU/ml.h; i.v. admininistered dose, 20 mg/kg) in the treatment of experimental meningitis in rabbits due to a pneumococcal strain highly resistant to penicillin (MIC of penicillin G, 4 micrograms/ml). The combination of both drugs significantly increased (P < 0.05) the killing rate (-0.60 +/- 0.23 delta log10 CFU/ml.h) compared to that produced by either monotherapy. These results were also confirmed in vitro.

Animals↗
PubMed1993

Triggering of pneumococcal autolysis by lysozyme.

Lysozyme had no effect on the rate of multiplication of growing cultures of Streptococcus pneumoniae, but it greatly reduced the lag period that precedes autolysis of these bacteria in stationary phase. Several experiments were done to understand the mechanism of this effect. Lysozyme had no hydrolytic activity on intact cell walls, and cell walls of pneumococci grown with or without lysozyme had identical composition and susceptibility to the pneumococcal autolysin. The acceleration of stationary-phase autolysis by lysozyme involved triggering of the pneumococcal autolytic enzyme since lysozyme had no detectable effect on nonautolysing (LytA-) mutants and heat-inactivated lysozyme completely lacking enzymatic activity was as effective as the nondenatured enzyme in facilitating stationary-phase autolysis. The role of lysozyme in host defense against pneumococcal infection remains elusive.

Animals↗
PubMed1988

[Are cephalosporins more active than penicillin G in poisoning with the deadly Amanita?].

High dose penicillin-G has been found empirically to be effective against liver cell damage in amanita mushroom poisoning. We have recently found that betalactam antibiotics inhibit eukaryotic DNA polymerase-alpha, penicillins being more active than cephalosporins, and this may explain the antagonistic effect of penicillin-G against amanitin toxicity. Preliminary experiments in liver cell cultures and in mice are summarized, as well as first clinical experience pointing to the possibility that cephalosporins may be more effective against amanita mushroom toxicity than penicillin-G.

Animals↗