Search

Summary Listeria monocytogenes endocarditis is rare. The authors report a case involving a porcine prosthetic valve in an immunosuppressed patient. Eight blood cultures developed L. monocytogenes . The culture of the resected cardiac valve was positive after six weeks of antibiotics (thiophenicol-gentamicin and vancomycin-gentamicin). Cure was obtained after surgical therapy and medical therapy (five months).

Tetraplegia developed abruptly in an 11-y-old with pneumococcal meningitis. Magnetic resonance imaging showed multiple hyperintensities at the brainstem-spinal cord junction. Serological tests were positive for Mycoplasma pneumoniae (microparticle agglutination and specific IgMs). Erythromycin and dexamethasone were started promptly, and 10 d later the patient was discharged with normal neurological function.Tetraplegia during the course of pneumococcal meningitis in an 11-y-old girl disappeared after treatment with ceftriaxone, erythromycin and dexamethasone.

Objective:To identify risk factors associated with surgical-site infection according to the depth of infection, the cardiac procedure, and the National Nosocomial Infections Surveillance System risk index.Design:Prospective survey conducted during a 12-month period.Setting:A 48-bed cardiac surgical department in a teaching hospital.Patients:Patients admitted for cardiac surgery between February 2002 and January 2003.Results:Surgical-site infections were diagnosed in 3% of the patients (38 of 1,268). Of the 38 surgical-site infections, 20 were superficial incisional infections and 18 were mediastinitis for incidence rates of 1.6% and 1.4%, respectively. Cultures were positive in 28 cases and the most commonly isolated pathogen wasStaphylococcus. A National Nosocomial Infections Surveillance System risk index score of 2 or greater was associated with a risk of surgical-site infection (relative risk, 2.4;P< .004). Heart transplantation, mechanical circulatory assistance, coronary artery bypass graft with the use of internal mammary artery, and reoperation for cardiac tamponade or pericard effusion were independent risk factors associated with surgical-site infection.Conclusions:Data surveillance using incidence rates stratified by cardiac procedure and type of infection is relevant to improving infection control efforts. Risk factors in patients who developed superficial infection were different from those in patients who developed mediastinitis. Coronary artery bypass graft using internal mammary artery was associated with a high risk of surgical-site infection, and independent factors such as reoperation for cardiac tamponade or pericard effusion increased the risk of infection.

Indifference or moderate antagonism of linezolid combined with other antibiotics in vitro and in vivo have mainly been reported in the literature. We have assessed the in vitro activities of linezolid, alone or in combination with imipenem, against methicillin-resistant Staphylococcus aureus (MRSA) strains using the dynamic checkerboard and time-kill curve methods. Linezolid and low concentrations of imipenem had a synergistic effect, leading us to evaluate the in vivo antibacterial activity of the combination using the rabbit endocarditis experimental model. Two MRSA strains were used for in vivo experiments: one was a heterogeneous glycopeptide-intermediate clinical S. aureus strain isolated from blood cultures, and the other was the S. aureus COL reference strain. Animals infected with one of two MRSA strains were randomly assigned to one of the following treatments: no treatment (controls), linezolid (simulating a dose in humans of 10 mg/kg of body weight every 12 h), a constant intravenous infusion of imipenem (which allowed the steady-state concentration of about 1/32 the MIC of imipenem for each strain to be reached in serum), or the combination of both treatments. Linezolid and imipenem as monotherapies exhibited no bactericidal activity against either strain. The combination of linezolid plus imipenem showed in vivo bactericidal activity that corresponded to a decrease of at least 4.5 log CFU/g of vegetation compared to the counts for the controls. In conclusion, the combination exhibited synergistic and bactericidal activities against two MRSA strains after 5 days of treatment. The combination of linezolid plus imipenem appears to be promising for the treatment of severe MRSA infections and merits further investigations to explore the mechanism underlying the synergy between the two drugs.

The decision of an antibiotic treatment depends first on clinical and bacteriological data. Then PK/PD (pharmacodynamics/pharmacokinetics) of antibiotics must be taken into account in order to optimise the dosing regimen, and to reach the targeted serum concentrations. The good oral bioavailability of some drugs allows the use of the oral route, at the beginning of the treatment, or shortly after an initial successful i.v. administration, even in severe infections.

Efforts to enhance standard precautions and to isolate patients with positive routine clinical cultures during 3 years were insufficient to decrease multidrug-resistant bacteria infection rates. Routine screening for carriage in high-risk patients may be necessary to hait transmission and control the hospital reservoir.

Indifference or even antagonism has mainly been reported with combinations including linezolid. The presence of in vitro antagonism is not always correlated with in vivo failure. The purpose of this study was to evaluate the in vivo activity of linezolid combined with gentamicin using a methicillin-resistant Staphylococcus aureus (MRSA) endocarditis experimental model. A human-like pharmacokinetic simulation was used for linezolid and gentamicin to improve the extrapolation of the results to human therapy. Contrary to the antagonism previously described in vitro, linezolid combined with gentamicin exhibited bactericidal activity on the two strains with a decrease of at least 4log 10 cfu/g of vegetation compared with controls. These data suggest that linezolid plus gentamicin could be an appropriate combination for the treatment of severe MRSA infections.

International audience; To understand the regulation of the MexAB OprM efflux system in a clinical strain of Pseudomonas aeruginosa presenting a decreased susceptibility to ticarcillin and aztreonam, the mexR repressor gene was amplified by polymerase chain reaction (PCR) and was shown to be disrupted by an insertion sequence of more than 2 kb, with characteristic direct and inverted repeat sequences. Sequencing revealed a 2131-bp IS21 insertion sequence. A reverse transcription PCR method was used to quantify mexA transcripts and showed an increased transcription rate of mexA in this strain, compared with a PAO1 control strain. The nalB phenotype in P. aeruginosa may be due to point mutations, but also to the presence of an insertion sequence in the mexR regulator gene.

Significant differences between animal and human pharmacokinetics may be responsible for the conflicting results of experimental studies. This study determined the impact of human pharmacokinetic simulation (HPS) on gentamicin activity in an Enterococcus faecalis endocarditis model. The decrease in bacterial counts was greater with HPS than with a dose-equivalent regimen without HPS.

The in vitro activity of the oxazolidinone linezolid was studied alone and in combination with three antibiotics acting on different cellular targets. Oxazolidinones are bacterial protein synthesis inhibitors that act at a very early stage by preventing the formation of the initiation complex. Combinations of linezolid with gentamicin, vancomycin or rifampicin were evaluated against four methicillin-resistant Staphylococcus aureus strains, using killing curves in conjunction with scanning electron microscopy. Time-kill curves were performed over 24 h using an inoculum of 5 x 10(6)- 1 x 10(7) cfu/mL. Linezolid was studied at concentrations of 1 x, 4 x and 8 x MIC, with partner drugs at 8 x MIC. Addition of linezolid resulted in a decrease of antibacterial activity for gentamicin and vancomycin, and linezolid was antagonistic to the early bactericidal activity of gentamicin. Linezolid, in combination with rifampicin, showed an additive interaction for susceptible strains and inhibited rifampicin-resistant variants. Linezolid plus rifampicin appeared to be the most active combination against methicillin-resistant S. aureus strains in time-kill experiments.

Linezolid is the first drug issued from the oxazolidinones, a novel class of antimicrobial agents with potent activity against gram-positive pathogens. A rabbit endocarditis model was used to compare the in vivo activities of different linezolid regimens mimicking intermittent dosing of 10 mg/kg of body weight every 12 h for 5 days or continuous (constant-rate) infusion of a daily dose of 20 mg/kg (for 5 days) or 40 mg/kg (for 3 and 5 days) and the activities of intermittent dosing and continuous infusion of vancomycin (for 5 days). The in vivo activities of these regimens were tested against three strains of methicillin-resistant Staphylococcus aureus . A human-like pharmacokinetic simulation was used for linezolid in order to improve the extrapolation of the results to human therapy. All linezolid regimens significantly reduced the numbers of S. aureus cells in aortic valve vegetations compared to the numbers in the control groups. Linezolid intermittent dosing had an in vivo bacteriostatic effect. Switching from intermittent dosing to continuous infusion (at the same dose) led to in vivo bactericidal activity, with a decrease of at least 3 log 10 CFU/g of vegetation compared to the counts for the controls. After 5 days of treatment, continuous infusion of linezolid (corresponding to a daily dose of 40 mg/kg in humans) seemed to be at least as effective as vancomycin against the three strains. No resistant variant was isolated from the vegetations during any of the treatments. These data suggest that continuous infusion of linezolid could be an appropriate alternative to the use of glycopeptides for the treatment of severe methicillin-resistant S. aureus infections.

Sir, In a previous study we demonstrated that doripenem, the most recently approved carbapenem, exhibited antimicrobial activity similar to that of imipenem or meropenem in an experimental rabbit model of susceptible Pseudomonas aeruginosa pneumonia. Mutational inactivation of oprD is known to be the main mechanism of imipenem resistance in the absence of acquired carbapenemase. Although oprD inactivation also increases the MICs of meropenem and doripenem, clinical resistance to these drugs is thought to require additional mechanisms. In this work we compared the efficacy of doripenem versus imipenem or meropenem against a resistant oprD-inactive strain of P. aeruginosa in an experimental model. The experimental rabbit model of pneumonia has been described previously. The bacterial strain was a DoprD PAO1, which is resistant to carbapenems after inactivation of OprD porin, a carbapenem-specific transport porin. This strain was provided by courtesy of Professor P. Plesiat, Besancon, France. MICs of meropenem, doripenem and imipenem were 8, 1 and 16 mg/L, respectively. Antibiotics were delivered through a venous catheter, with changing infusion rates determined by computer-controlled electric pumps, in order to simulate the pharmacokinetics observed in human serum. Animals were randomly assigned to four groups: (i) controls (no treatment); (ii) meropenem group [computer-controlled syringe-pump infusion to simulate a human equivalent (HE) dosage of meropenem of 1 g three times daily]; (iii) doripenem group (simulating an HE dosage of doripenem of 0.5 g three times daily); and (iv) imipenem group (simulating an HE dosage of imipenem of 1 g three times daily). Evaluation of infection was performed at the end of treatment (2 days). The spleen and both lungs from each animal were weighed and homogenized in 1 mL of saline buffer and used for quantitative cultures on agar for 24 h at 378C. Viable counts after 24 h of incubation were expressed as the mean+SD log10 cfu/g of lung. Spleen culture results were expressed quantitatively (positive or negative). From each animal, plasma antibiotic concentrations were determined by a microbioassay to obtain a pharmacokinetic analysis. Selection of variants resistant in vivo to doripenem, meropenem or imipenem was evaluated by spreading undiluted homogenates on agar plates that contained the appropriate antibiotic at a concentration of 4-fold the MIC. Bacterial counts were determined after 48 h of incubation at 378C. Quantitative variables were compared using one-way analysis of variance. This analysis was completed with a post hoc Bonferroni test. Proportions (percentages) were compared using Fisher’s exact test. P,0.05 was considered statistically significant. Animals were treated in accordance with institutional policies and the guidelines stipulated by the animal welfare committee. The Committee of Animal Ethics of the University of Nantes approved all animal experimentation in this study. Mean pulmonary bacterial loads were 3.1+1.3, 2.6+0.4 and 2.8+0.7 log10 cfu/g for meropenem, doripenem and imipenem, respectively, compared with 5.9+0.8 log10 cfu/g for control animals. The results of these pulmonary bacterial counts are shown in Figure 1; they were significantly lower in the treated animals compared with the controls (P,0.05), but were similar between the different antibiotic regimens. The proportions of positive versus negative spleen cultures for controls, meropenem, doripenem and imipenem were 4/3, 3/4, 1/6 and 2/7, respectively; they were not statistically different. No resistant mutants were isolated from any of the post-treatment biological samples.

Introduction – objectifs MedQual, avec un reseau de laboratoires de biologie medicale (LBM), suit l’evolution des souches d’ Escherichia coli ( E. coli ) isolees en milieu communautaire. Materiels et methodes Toutes les souches d’ E. coli isolees par le reseau de LBM, de janvier 2008 a decembre 2013, sont incluses dans cette etude, nous permettant de suivre l’evolution des E. coli productrices de BLSE de 2008 a 2013. Resultats 397 032 antibiogrammes ont ete recueillis : 97 % des E. coli ont ete isoles de prelevements urinaires. La proportion d’ E. coli resistants aux cephalosporines de troisieme generation a augmente de 2,2 % en 2008 a 3,9 % en 2013 (P E. coli , la production de BLSE a augmente graduellement passant de 1,4 % en 2008 a 3,2 % en 2013 (P E. coli (NS). En 2008, la moyenne d’âge des patients etait de 55 ans (57 en 2013) [âge median : 58 en 2008 versus 62 en 2013]. E. coli etait essentiellement retrouve chez des femmes (80 % en 2008 vs 86 % en 2013). Conclusion au cours de ces 6 annees de recueil, nous avons identifie une stabilite des souches d’ E. coli productrices de cephalosporinase, alors que la production de BLSE chez E. coli augmente significativement depuis 2008. Ces donnees sont communiquees aux prescripteurs pour les aider a ajuster leurs prescriptions antibiotiques a l’ecologie bacterienne locale.

An association between chorioamnionitis and periventricular leukomalacia has been reported in human preterm infants. However, whether this link is causal has not been convincingly established, and the underlying molecular mechanisms remain unclear. The objective of this study was to establish a reproducible model of cerebral white matter disease in preterm rabbits after intrauterine infection. Escherichia coli was inoculated into both uterine horns of laparotomized pregnant rabbits when gestation was 80% complete. The fetuses were delivered by cesarean section and killed 12, 24, or 48 h after the inoculation. Programmed cell death in the white matter was evaluated by hematoxylin-eosin-saffron staining and in situ fragmented DNA labeling (terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling). In a first group of 14 pregnant rabbits not treated with antibiotics, all fetuses delivered 48 h after inoculation were stillborn, whereas fetuses extracted 12 or 24 h after inoculation were alive. No significant cell death was detected in the live fetuses compared with the control noninfected rabbits. In a second group of five pregnant rabbits treated with ceftriaxone initiated 24 h after the inoculation and continued until cesarean section was performed 48 h after inoculation, 13 fetuses were alive, but all showed evidence of extensive programmed cell death in the white matter by hematoxylin-eosin-saffron staining and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling. White matter damage became histologically detectable only 48 h after inoculation. Three of the 13 brains displayed periventricular white matter cysts mimicking human cystic periventricular leukomalacia. The high reproducibility of white matter damage in our model should permit further studies aimed at unraveling the molecular mechanisms of periventricular leukomalacia.

The evaluation of drugs in vivo is often based on experimental models using small animals such as mice, rats and rabbits. However, these models could be improved to correspond more closely to the human situation if the pharmacokinetics of the drugs tested in animals were similar to that observed in humans. The use of a computer-controlled pump allowing an adequate flow of tobramycin and amikacin to be infused into rabbits enabled us to simulate the human pharmacokinetics of these antibiotics in vivo in this study. The function defining the rate of infusion required to perform the simulation of an intravenous bolus was first determined generally and symbolically for linear pharmacokinetic models independently from the number of compartments involved. The practical simulation of a decreasing monoexponential serum profile with a half-life of 2 h (one-compartment model for the human pharmacokinetics of aminoglycosides) was then studied for tobramycin and amikacin on the basis of a two-compartment model in the animal. The kinetics obtained had an apparent elimination half-life of 1.97 and 1.86 h, respectively. Linearity of the semilogarithmic regressions of the profiles obtained was quite sound. Finally, an a posteriori analysis of the pharmacokinetic model and its parameters is proposed on the basis of the results obtained after simulation.

We developed two multidisciplinary tutorial programs (TOBRA-DIDACT and VANCO-DIDACT) for teaching the basic principles of antibiotic drug monitoring by simulation of repeated administrations to fictitious patients whose physio-pathologic characteristics were pre-defined in the programs. To illustrate the two types of bactericidal kinetics, we have chosen one time-dependent (vancomycin) and one concentration-dependent (tobramycin) antibiotic. These computer-assisted programs operate on an interactive mode. In each of them, three main steps are connected: (1) Various types of clinical cases are submitted to the student: for each of them, case report includes clinical characteristics, location of infection, bacterial strain and minimal bactericidal concentration. These data must be taken into account during the following steps. (2) The student has to establish the treatment schedule: route of administration, dose for each injection, intervals between injections and duration of infusion. (3) The result of the dosage scheme proposed by the student is represented by a simulation of plotting antibiotic plasma concentrations vs. time during the first 4 days of treatment. These curves are obtained by a monoexponential (TOBRA-DIDACT) or biexponential (VANCO-DIDACT) pharmacokinetic model. Peak and trough concentrations are calculated at steady-state. An expert system provides a commentary with each result to evaluate the efficacy of the treatment and to assist the student in improving his prescription. TOBRA-DIDACT and VANCO-DIDACT illustrate the influence of age, obesity, renal impairment, location of infection and bacterial strain on antibiotic therapy. They also show the role of route of administration, dosing and intervals between injections on therapeutic response.(ABSTRACT TRUNCATED AT 250 WORDS)

International audience; The diffusion of antibiotics in endocarditis vegetation bacterial masses has not been described, although it may influence the efficacy of antibiotic therapy in endocarditis. The objective of this work was to assess the diffusion of ofloxacin in experimental endocarditis vegetation bacterial masses using synchrotron-radiation UV fluorescence microspectroscopy. Streptococcal endocarditis was induced in 5 rabbits. Three animals received an unique IV injection of 150 mg/kg ofloxacin, and 2 control rabbits were left untreated. Two fluorescence microscopes were coupled to a synchrotron beam for excitation at 275 nm. A spectral microscope collected fluorescence spectra between 285 and 550 nm. A second, full field microscope was used with bandpass filters at 510-560 nm. Spectra of ofloxacin-treated vegetations presented higher fluorescence between 390 and 540 nm than control. Full field imaging showed that ofloxacin increased fluorescence between 510 and 560 nm. Ofloxacin diffused into vegetation bacterial masses, although it accumulated in their immediate neighborhood. Fluorescence images additionally suggested an ofloxacin concentration gradient between the vegetation peripheral and central areas. In conclusion, ofloxacin diffuses into vegetation bacterial masses, but it accumulates in their immediate neighborhood. Synchrotron radiation UV fluorescence microscopy is a new tool for assessment of antibiotic diffusion in the endocarditis vegetation bacterial masses.

Aminoglycosides are commonly used in the treatment of nosocomial pneumonia in association with beta-lactams. Unfortunately, penetration of intravenously administered aminoglycosides into the lung tissue remains low. In animal models, aerosolization of these drugs provides high lung concentrations and low serum levels. Three-hundred milligrams of tobramycin and 1 ml of 99mTc-DTPA were administered via a pneumatic nebulizer to five healthy volunteers and to five mechanically ventilated patients. Lung scintigraphy was then performed, and plasma and urine pharmacokinetics were studied. In a second group of patients undergoing thoracic surgery, 300 mg of tobramycin alone were administered in the same way; a fragment of healthy lung was then removed, and tobramycin was measured. In the first group, the scintigraphy showed radioactivity distribution in the whole lungs both in healthy volunteers and in ventilated patients. Urine samples contained 5.5% of the initial amount of tobramycin. The mean serum half-life of tobramycin was 8.96 h in healthy volunteers and 11.23 h in ventilated patients. In the second group, mean lung tissue concentrations were 5.5 and 3.61 micrograms/g, respectively, 4 and 12 h after nebulization, respectively. Aerosolization of tobramycin thus produced high lung concentrations and low serum levels.

9 elderly and 9 younger adult patients, with proven post-operative lower urinary tract infection were treated with 400 mg of norfloxacin twice daily for 5 days. Pharmacokinetics of norfloxacin were measured on days 1 and 5. Compared to the younger adult patients, the elderly showed a decreased creatinine clearance and, following the last dose on day 5, an increased maximum plasma concentration of norfloxacin, an increased area under the concentration-time curve and a decreased total body clearance of norfloxacin. These results confirm that in elderly, as in younger adult patients, the pharmacokinetics of norfloxacin can be described by a linear model and accumulation of the drug during repetitive multiple doses is predictable. The differences between the two groups cannot be considered as clinically significant so that no dose change would be required in elderly patients within the range of creatinine clearance studied.

Objectifs MedQual, reseau ville hopital, assure une veille epidemiologique regionale prospective d’E. coli depuis janvier 2004. Cette surveillance permet de suivre la sensibilite aux antibiotiques les plus couramment utilises en milieu communautaire dont les fluoroquinolones. Methode Collaboration d’une trentaine de laboratoires d’analyses medicales de la region Pays-de-La-Loire. Recueil mensuel des donnees de l’antibiogramme avec mise a disposition des resultats sur le site Internet securise http://www.medqual.fr . Resultats Apres 4 ans de surveillance, 74 024 souches d’E. coli ont ete recueillies, isolees essentiellement des prelevements urinaires (97,1 %). La sensibilite pour la ciprofloxacine etait plus elevee que pour ofloxacine/norfloxacine. La sensibilite pour ofloxacine/norfloxacine est passee de 91,4 % en 2004 a 87,0 % en 2007. Pour la ciprofloxacine, elle semblait stable en 2004-2005, (94,5 % en 2004 et 94,0 % en 2005). Mais des 2006, elle diminuait legerement, passant de 92,8 % a 91,3 % en 2007. Parallelement, les consommations regionales ont augmente de 5,5 % pour ciprofloxacine, 15 % pour ofloxacine et 4,3 % pour norfloxacine entre 2004 et 2006. En Vendee, une disparite departementale etait observee : le pourcentage de souches d’E. coli resistantes a la ciprofloxacine etait plus eleve que dans les autres departements (11 % versus 8-9 %). Conclusion Le constat de disparites d’evolution des resistances aux fluoroquinolones au sein de la Region nous conduit a effectuer une analyse plus fine de ce phenomene a l’echelon departemental pour en comprendre les determinants. La promotion d’alternatives therapeutiques, la surveillance des fluoroquinolones et un usage raisonne de ces antibiotiques sont indispensables pour controler l’evolution de la resistance aux fluoroquinolones chez E. coli.

Since in-vitro methods for studying drug interactions are difficult to evaluate and different results occur with the chequerboard (isobolograms-FIC index) and killing curve methods, a new approach associating these two methods was used to study the ceftazidime-pefloxacin interaction. In 64 tubes in a chequerboard pattern, viable bacteria were counted at 0, 2.5, 5 and 24 h, by a microdilution method and a multiple inoculator replicating method. The bacterial inoculum consisted of 5 X 10(6)-10(7) cfu/ml. Twelve strains belonging to six genera were tested: Acinetobacter, Citrobacter, Enterobacter, Klebsiella, Serratia and Pseudomonas. During the first 5 h no antagonism was noted, but few differences in viable count equal to or greater than 2 log10 were observed. The results of the drug interaction were equivalent to those of the more rapid bactericidal antibiotic concentrations (ceftazidime or pefloxacin). At 24 h, synergy was observed: ceftazidime prevented the late regrowth noted with pefloxacin, but with Citrobacter spp. regrowth was also observed with ceftazidime and none of the combinations were bactericidal.

Resume La determination des concentrations minimales inhibitrices (CMI) permet d'apprehender la sensibilite et la resistance d'une bacterie ; sur des bacteries sensibles, ce parametre ne permet pas de predire l'efficacite de l'antibiotique. L'activite bactericide est un autre parametre qui, couple a la pharmacocinetique, peut permettre d'aborder la pharmacodynamie des antibiotiques et leur efficacite. Deux facteurs influencent l'importance de la destruction bacterienne : la concentration d'antiobiotique utilisee, le temps d'incubation. Pour certaines molecules, le premier parametre est primordial (antibiotiques concentration-dependant), pour d'autres le second predomine (antibiotiques temps-dependant). Sur les bacilles a Gram negatif la ceftriaxone tout comme les autres cephalosporines de 3eme generation et les ureidopenicillines fait partie de cette derniere classe. Une demi-vie longue (comme pour la ceftriaxone) correspond donc a un allongement du temps d'incubation et a une activite bactericide plus longue et plus durable. Sur les Staphylococcus aureus, la ceftriaxone tout comme les autres cephalosporines de sa generation n'est pas active sur les Staphylococcus aureus resistants a la meticilline. Par contre, sur les souches sensibles a la meticilline, son activite bactericide est temps dependante et ne s'exerce qu'apres un temps de latence generalement compris entre une et deux heures (comme pour l'ensemble des β-lactamines). L'activite bactericide de la ceftriaxone est donc favorisee par la pharmacocinetique particuliere qui se rapproche de la pharmacocinetique ideale d'un antibiotique temps dependant, telle qu'elle a ete definie dans des modeles experimentaux sur l'animal.

Resume Les auteurs decrivent un cas de septicemie avec pericardite purulente a Haemophilus influenzae de type b, resistant a l'Ampicilline chez un enfant de deux ans. La pericardite succede a une laryngite sous glottique surinfectee par un Haemophilus influenzae . La cardiomegalie radiologique est presente. Le diagnostic precoce associe a une antibiotherapie et a un drainage du liquide pericardique conditionne la survive de l'enfant. Dans l'attente des resultats bacteriologiques, le choix de l'antibiotique devrait se porter sur une cephalosporine de troisieme generation au cours des infections de l'enfant.

The critical concentration of antibiotic was calculated by using the agar diffusion method with disks containing different charges of antibiotic. It is currently possible to use different calculation formulas (based on Fick's law) devised by Cooper and Woodman (the best known) and by Vesterdal. The results obtained with the formulas were compared with the MIC results (obtained by the agar dilution method). A total of 91 strains and two cephalosporins (cefotaxime and ceftriaxone) were studied. The formula of Cooper and Woodman led to critical concentrations that were higher than the MIC, but concentrations obtained with the Vesterdal formula were closer to the MIC. The critical concentration was independent of method parameters (dilution, for example).

The objectives of this work were to compare the infrared spectra of bacterial endocarditis vegetation with those of native valvular tissue and the infrared spectra of vegetation bacterial masses with those of surrounding vegetation tissue. Streptococcal aortic endocarditis was induced in three rabbits. Vegetation slices were cryo-sectioned for study by Fourier transform infrared (FT-IR) microspectroscopy. Valvular apparatus, vegetation, and bacterial masses within the vegetation were localized on hematoxylin and eosin (H&E) stained contiguous slices. Infrared images of whole vegetations and images of bacterial masses were acquired with apertures set to 80 × 80 and 20 × 20 μm, respectively. Valvular apparatus and vegetation showed different infrared spectra, mainly in the amide I and amide II bands (1674–1518 cm−1), and at about 1450, 1400, 1340, 1280, 1240, 1200, 1080, and 1030 cm−1. Valvular collagen, elastin, and proteoglycans may explain these differences. Bacterial masses and surrounding vegetation showed different infrared patterns, mainly in the amide I and amide II bands and in the 1142–991 cm−1 carbohydrate spectral range. Bacterial nucleic acids and polysaccharides may partly explain these differences. Study of experimental endocarditis vegetation using FT-IR microspectroscopy distinguishes (1) the vegetation from the valvular tissue, and (2) the bacterial masses from the surrounding tissue. This study demonstrates for the first time that FT-IR microspectroscopy is able to detect bacterial growth in infected tissue. FT-IR microspectroscopy appears to be a useful tool for investigation of the biochemical structure of endocarditis vegetation.

Resume Les auteurs decrivent un cas d'infection a Gemella haemolysans isole d'une cavite de pneumectomie et dont l'evolution a ete favorable, sous traitement a base de pefloxacine et dibekacine, associe a un drainage.