[Kinetics of Pseudomonas aeruginosa virulence gene expression during chronic lung infection in the murine model]. / Cinétique d'expression des gènes de virulence de Pseudomonas aeruginosa au cours d'une infection pulmonaire chronique dans le modèle murin.

UNLABELLED: Pseudomonas aeruginosa is a Gram-negative bacillus frequently encountered in human diseases. P. aeruginosa produces a large number of secreted and cell associated virulence factors. Their production is coordinated by various systems of gene regulation. The correlation and sequential intervention of regulation systems during a pulmonary infection have not been determined yet. OBJECTIVE: The aim of this study was to analyze the expression of three P. aeruginosa virulence genes (exoS, lasI, and algD) during the first seven days of chronic lung infection. To do so, mice were infected intratracheally with agarose beads containing P. aeruginosa. RESULTS: The results were a progressive decrease of exoS transcription and an increase of algD, and lasI transcription during infection. This dynamic evolution was consistent with the clinical observation, which demonstrated a progressive loss of type III secretion system function and an increase in the mucoid phenotype development in P. aeruginosa strains from cystic fibrosis patients. CONCLUSION: The development of a P. aeruginosa pulmonary chronic infection associates a decrease of gene expression related to a type III secretion system and an increase of alginate production.

[Early neonatal bacterial infections: could superficial bacteriologic samples at birth be limited?]. / Infections bactériennes néonatales précoces en maternité: peut-on limiter les prélèvements bactériologiques périphériques en salle de naissance ?

INTRODUCTION: Without promptly started antibiotic therapy, early neonatal bacterial infections incur a significant mortality. Superficial bacteriologic samples at birth have in France a real place for the diagnosis and the decision to treat a neonate. OBJECTIVES: In order to limit their indication and their choice, the aim of this article was to describe the proportion of neonates with samples and to determine the diagnostic value of the gastric aspirate, the ear swab and the placental sample. METHODS: Neonates born in the CHRU of Lille in 2005 and staying in the maternity ward were prospectively included. Criteria for samples, type of samples and diagnosis taken were noted. Sensibility, specificity, positive and negative predictive values and likelihood ratios for a positive test and a negative test were calculated. RESULTS AND CONCLUSION: This study included 3918 neonates; 1.7% (65 children) were infected according to our criteria; 42.3% received bacteriologic samples. In accordance with the Anaes guidelines (2002), if mothers were Group B Streptococci positive and received intrapartum antibiotics (up to 2 injections) or did not have any screening test without any other indication of samples, the neonate did not have to receive bacteriologic samples. The gastric aspirate was the best exam thanks to the excellent negative predictive value of its direct examination: 99.4% (IC 95%: 98.8-99.7), its high likelihood ratio for a positive test: 10.04 (IC 95%: 8.29-12.15) and its low likelihood ratio for a negative test: 0.16 (IC 95%: 0.09-0.29); this sample could restrict the antibiotics' ratio given to the neonate. Placental sample could be taken only in certain indications.

Decline in pneumococcal meningitis after the introduction of the heptavalent-pneumococcal conjugate vaccine in northern France.

BACKGROUND: The impact of the heptavalent-pneumococcal conjugate vaccine on the incidence of pneumococcal meningitis in Europe has not yet been assessed. OBJECTIVE: To determine whether heptavalent-pneumococcal conjugate vaccine implementation in northern France has resulted in a decrease in the incidence of pneumococcal meningitis in children. DESIGN: Multicentre retrospective cohort study from 2000 through 2005. SETTINGS: All paediatric departments of the 18 hospitals in northern France. PATIENTS: Patients <18 years of age, admitted for laboratory-confirmed pneumococcal meningitis during the study period, were included. INTERVENTIONS: Data were collected from medical files and the microbiological laboratories of each hospital and compared with the regional hospital discharge codes, using a capture-recapture method. MAIN OUTCOME MEASURES: The study assessed and compared global and age-related incidence rates of pneumococcal meningitis in 2001 (pre-vaccine era) and 2005. RESULTS: 77 cases were found through the capture-recapture method. The incidence rate of pneumococcal meningitis varied from 1.65/100,000 children <18 years in 2001 to 0.80/100,000 children in 2005 (53% reduction, 95% CI 31 to 74; p = 0.08). This has so far been significant only for children <2 years of age (8.9/100,000 in 2001 to 1.8/100,000 in 2005; 82% reduction, 95% CI 52 to 95; p = 0.03). CONCLUSION: A decline in pneumococcal meningitis has been observed in infants since heptavalent-pneumococcal conjugate vaccination began in our area.

[Self-collected vaginal swabs to diagnosis bacterial vaginosis during pregnancy: A pilot study]. / Autoprélèvement vaginal à la recherche d'une vaginose bactérienne pendant la grossesse: étude pilote.

OBJECTIVE: To study the feasibility of a screening for bacterial vaginosis by a self-collected vaginal swab during pregnancy. To measure bacterial vaginosis prevalence in a non-representative sample of women. PATIENTS AND METHODS: A self-collected swab was suggested to 398 women who consulted between 15 and 33 weeks of gestation in three different centres. Gram stain evaluation using Nugent criteria was used for the diagnosis of bacterial vaginosis. RESULTS: Three hundred and forty-one women agreed to take part in the study (86%). The quality of the swabs was satisfactory in 93% of the cases. Concerning the 15 non-interpretable slides, the cellular and bacterial density was too poor, owing to a poor quality or a low vaginal flora. Thirty-one women (9%) had a bacterial vaginosis--Nugent score included between 7 and 10--and this frequency did not vary according to the centre. Thirty-five women (10%) had an intermediate flora--score between 4 and 6--and this result varied from 2 to 12% depending on the centre, but the difference was not significant. DISCUSSION AND CONCLUSION: Self-collected swabs to detect bacterial vaginosis are well accepted by most of pregnant women, and the quality of the swabs seems to be satisfactory. In case vaginal flora is intermediate--between 4 and 6--the interpretation of the slides could be difficult.

[Evaluation of a new E-test method for antimicrobial sensitivity testing of Pseudomonas aeruginosa isolates from cystic fibrosis]. / Etude multicentrique portant sur l'évaluation d'une méthode simplifiée d'analyse bactériologique dans la surveillance des infections bronchiques à Pseudomonas aeruginosa survenant au cours de la mucoviscidose.

BACKGROUND: Sputum bacteriological analysis of cystic fibrosis (CF) patients colonised by Pseudomonas aeruginosa is difficult. The bronchial persistence of these bacteria involves phenotypical modifications and the many antibiotic treatments result in emergence of multiresistant strains. The aim of this study is to evaluate a new fast identification and sensitivity testing method of P. aeruginosa and other pathogenic bacteria in sputum of CF patients. It is based on applying a gradient of antibiotic (E-test strip) onto an agar plate inoculated with the sputum. OBSERVATIONS: 310 sputum, collected from adults and children colonised by P. aeruginosa, were analysed by this new method. This method allowed a direct reading of the minimal concentration of antibiotic that inhibited the totality of Gram-negative strains and the detection of resistant pathogenic bacteria inside the ellipse of inhibition. Results obtained by this new method were compared with the conventional method for identification and antimicrobial sensitivity. CONCLUSION: This new method, studying with CF patient colonised by P. aeruginosa, appears interesting, with a sensibility equal or higher than 89% in detection of the bacteria and their sensitivity to antibiotics. Furthermore it allows a saving of time and simplified results.

Effect of intermittent inhaled tobramycin on sputum cytokine profiles in cystic fibrosis.

OBJECTIVES: The aim of this study was to evaluate the anti-inflammatory properties of intermittent inhaled tobramycin. METHODS: To establish this, we initiated a prospective study to measure the concentration of the three pro-inflammatory cytokines IL-8, IL-6 and TNF-alpha in the sputum from 20 cystic fibrosis (CF) patients (15 teenagers and 5 young adults) during cycles and off cycles. RESULTS: A significant decrease in IL-8 (P = 0.001) and a more moderate decrease in IL-6 (P = 0.046) and TNF-alpha (P = 0.052) levels were observed during cycles, even if no significant decrease in the number of leucocytes was observed. CONCLUSIONS: These results associated with a decrease in the Pseudomonas aeruginosa population can contribute in part to the beneficial effect of intermittent inhaled tobramycin on pulmonary function.

Energetic cost of physical activity in cystic fibrosis children during Pseudomonas aeruginosa pulmonary exacerbation.

Chronic pulmonary infection by Pseudomonas aeruginosa is observed in 50% of patients with cystic fibrosis and requires the use of recurrent intravenous therapy. A decrease of resting energy expenditure (REE) and an increase of physical activity (PA) after intravenous anti-P. aeruginosa therapy (IVAT) is observed while total energy expenditure (TEE) does not change. A decrease in the energetic cost of physical activity (ECPA) could be hypothesized but has never been studied. Our aim was to assess the evolution of ECPA after home IVAT in both standardized condition at hospital and in free-living condition twice before and after IVAT. Sixteen CF patients (nine boys, seven girls) chronically colonized by P. aeruginosa with a mean age of 12.1+/-2.3 years (range 7.1-14.6) were studied before and after IVAT. Each patient passed throughout a visit in hospital: weight, height and fat-free mass were measured. Then, energy expenditure (EE) measured by indirect calorimetry and heart rate (HR) were simultaneously recorded at different levels of PA: REE, and at different intensity of physical activities on a cycloergometer using an incremental increase of the power brake force. Physical activity energy expenditure (PAEE) was computed in laboratory condition using PAEE=EE-BEE (basal energy expenditure). Linear regression between PAEE and power brake force was fitted for each patient before and after IVAT. ECPA in standardized conditions was compared at different range of power brake force using area under the curve (AUC). After coming back at home, 24 h TEE using the heart rate monitoring technique and PA by triaxial accelerometry were simultaneously measured in free-living condition for 24 h during a school day. ECPA in free-living conditions was compared by the ratio PAEE:PA where PAEE=DEE-REE (DEE=daily energy expenditure). After IVAT, median AUC between 60 and 90 W in standardized condition decreased significantly by -15.4% (median 14.9, range 8.8-30.3 vs. median 12.6, range 8.5-17.6; P<0.05, Wilcoxon rank test) while the decrease for lower range of power work load did not reach significance. Spearman correlation was significant between variations of forced expiratory volume in 1 s and variation of AUC at 30-60 W before and after IVAT in standardized condition. In free-living conditions, ratio PAEE/PA did not vary significantly (median 3.4, range 1.6-6.4 vs. median 2.8, range 1.4-4.8; NS). Our data demonstrate a decrease of ECPA after IVAT in standardized conditions for moderate level of PA (60-90 W), but not in free-living conditions. The decrease of ECPA was probably due to a decrease in the energetic cost of breathing after IVAT, that is particularly relevant to promote PA in CF patients.

[Epidemiology of infections associated to "Burkholderia cepacia complex" in the course of cystic fibrosis]. / Epidémiologie des infections provoquées par les bactéries du "complexe Burkholderia cepacia" au course de la mucoviscidose.

Within a few years bacteriological knowledge on Burkholderia cepacia species has progressed considerably. Within bacterial classification (taxonomy), B. cepacia gathers eight species and one species on standby of nomenclature (genomovar VI); the whole of these species constitutes the "B. cepacia complex" or B. cepacia "sensu lato" and the denomination B. cepacia "sensu stricto" is attributed to the genomovar I. These new data call into question the knowledge on the clinic and the epidemiology of B. cepacia "sensu lato" infection in the course of cystic fibrosis. Among these newly described species, B. cenocepacia (formerly genomovar III) and B. multivorans (formerly genomovar II) are the most frequent species and together they represent more than 90% of infections associated to "B. cepacia complex" in the course of cystic fibrosis. B. cenocepacia is often associated to the "cepacia syndrome" which is characterized as a fatal necrotizing pneumonia with bacteremia. The progress of molecular epidemiology allowed the description of bacterial clones of which some are highly transmissible from person-to-person. Their distribution varies according to the species and the geography. The identification of these new species appears particularly difficult and, by the fact, the data on taxonomy and molecular epidemiology can be provided only by highly specialized reference centers.

[Evaluation of a E-test method to detect bactericidy of beta lactam-aminoglycoside associations against Pseudomonas aeruginosa isolates from cystic fibrosis]. / Mise au point d'une méthode de mesure d'associations d'antibiotiques bactéricides par superposition de bandelettes E-test((R)) appliquée aux souches de Pseudomonas aeruginosa isolées au cours de la mucoviscidose.

BACKGROUND: Pulmonary infectious exacerbations with Pseudomonas aeruginosa are the major problem for patients with cystic fibrosis. Emergence of multi-resistant mucoid strains leads to complicate the choice of antibiotherapy. Therefore, synergic and bactericidal treatment must be used. Then, it is interesting to estimate the bactericidal activity of antibiotics associations in order to optimise the treatment. The aim of this work is to describe a new method of bactericidal antibiotics combinations by superimposing 2 E-test strips and to compare results with those obtained with a broth bactericidal method chosen as reference method. OBSERVATIONS: Twenty strains of P. aeruginosa (13 mucoïd and 7 non mucoïd) were selected from expectorants of cystic fibrosis children. Four antibiotics combinations were tested (ceftazidime/tobramycine, cefepime/tobramycine, ceftazidime/amikacine, cefepime/amikacine). Two antibiotics combinations by superimposing E-test strips techniques were used: maximal concentration on maximal concentration (C(max)/C(max)) and minimal inhibitory concentration on minimal inhibitory concentration (MIC/MIC). The comparison of results between killing curves and superposition of E-test strips (C(max)/C(max)) show 88% agreements, 4% major discrepancies specially with mucoid strains and 8% minor discrepancies. The Cmax/Cmax method seems to give better results than MIC/MIC method. CONCLUSION: The superposition of E-test strips method is an attractive method: it is rapid, easy to use and well correlated to broth bactericidal method.

Validation of diffusion methods for macrolide susceptibility testing of Helicobacter pylori.

Helicobacter pylori resistance to macrolides is increasing, and the need for susceptibility testing has become crucial. The only standardized method is agar dilution, which is not adapted to clinical practice. The present work aimed: (1) to optimize the technical conditions and to assess the reproducibility of the E-test and disk diffusion method for macrolides susceptibility testing of H. pylori, and (2) to assess the performances of these two phenotypic methods in detecting strains harboring a resistance mechanism to macrolides. We used 191 isolates collected in nine centers of France and Belgium. Phenotypic tests were performed on Mueller-Hinton agar supplemented with 10% horse blood, inoculated with a 2-day-old H. pylori suspension (10(8) CFU/ml), and incubated for 72 hr at 37 degrees C under microaerophilic conditions. The reproducibility studied on two randomly selected strains was better for disk diffusion than for the E-test for both clarithromycin and erythromycin. For a subset of 10 strains, the MICs of erythromycin and clarithromycin did not differ from more than one two-fold dilution when determined by E-test or agar dilution method. The breakpoints were for MICs: 1 mg/L for both clarithromycin and erythromycin and for inhibition diameters, 22 mm for clarithromycin and 17 mm for erythromycin. There was a 100% concordance between susceptibility to erythromycin and clarithromycin. However, the susceptible and resistant populations were better separated by testing erythromycin. Of 34 resistant strains, two lacked the A2142G and A2143G point mutations in 23S rRNA by PCR-RFLP. None of 15 tested sensitive strains were positive for one of these two point mutations. For clinical practice, we recommend to assess macrolide susceptibility of H. pylori by using one of these two phenotypic methods under the described technical conditions.

Local antibiotic lock for the treatment of infections related to central catheters in parenteral nutrition in children.

BACKGROUND: Central venous catheter-related (CVC) infections represent the most common complication of parenteral nutrition. These infections are usually treated by means of long-term systemic antibiotic treatment. The objective of this study was to determine the efficacy of combining a local antibiotic lock with a short systemic double antibiotic to treat CVC-related staphylococci infections. METHODS: Any child with coagulase-negative staphylococci or Staphylococcus aureus septicemia, confirmed by a positive blood culture, was included in the study. A double antibiotic systemic treatment composed of amikacin and teicoplanin was started and continued for 5 days. The antibiotic treatment was combined from the first day (D0) with a local teicoplanin lock, which was left for 12 hours a day in the catheter for 15 days. Parenteral nutrition was continued on a nocturnal cyclic mode during antibiotic treatment. The efficacy of the treatment was evaluated by clinical (body temperature), biologic [C-reactive protein levels (CRP)], and bacteriologic (blood culture) measures. RESULTS: Twenty CVC-related infection episodes in 13 patients were analyzed for the study. In the initial biologic test, CRP varied from 2 to 130 mg/L (mean 43 mg/L). After 3 days of treatment, CRP varied from 2 to 61 mg/L (mean 12 mg/L). The median time until normalization of temperature and CRP levels after the beginning of antibiotic treatment was 3.2 days (range 1 to 14 days) and 6.2 days (range 2 to 19 days), respectively. All blood cultures were negative for infection 48 hours after stopping the treatment. Only 1 therapeutic failure was observed during the treatment. The patient had persistent signs of clinical septicemia that required removal of the CVC. Two catheter-related infection recurrences were observed in the month after termination of the local antibiotic lock, which also required removal of the CVC. The central venous catheter was maintained in the other cases. CONCLUSIONS: Teicoplanin antibiotic locks, combined with a short conventional systemic antibiotic treatment and continuation of cyclic parenteral nutrition, seem effective and well-tolerated treatments for CVC infections.

[Acquisition of secondary resistance after failure of a first treatment of Helicobacter pylori infection in children]. / Acquisition d'une résistance secondaire après échec d'un premier traitement lors de l'infection à Helicobacter pylori chez l'enfant.

AIMS: To assess the frequency of acquisition of secondary Helicobacter pylori resistant-strains after a first course of antimicrobial treatment. PATIENTS AND METHODS: A retrospective study was performed during the 1994-2000 period, in 15 girls and eight boys, mean age 10.9 +/- 4.8 years (1.4-17 years), with Helicobacter pylori gastritis (culture and antimicrobial susceptibility) presenting a failure of first course treatment, with during one week a proton pump inhibitor and amoxicillin together with either clarithromycin (n = 14) or metronidazole (n = 9). Two endoscopies were performed, the first at the time of diagnosis and the second after the failure of bacterial eradication demonstrated by a positive 13C urea breath test six weeks after the end of treatment. Antimicrobial susceptibility of all Helicobacter pylori strains was tested after each endoscopy and before starting a second course of the treatment. RESULTS: Comparison of antimicrobial susceptibility before and after the first course of treatment showed that Helicobacter pylori strains were all sensitive to amoxicillin, clarithromycin-resistant in eight children (34.7%) before treatment vs 12 (52.1%) after treatment, p = 0.42, ns, metronidazole-resistant in 13 (56.5%) vs 12 (52.1%), p = 0.80, ns, and both clarithromycin and metronidazole-resistant in four (17.3%) vs seven (30.4%), p = 0.63, ns. Among the 14 children treated by a triple therapy including clarithromycin, three (21.4%) developed a secondary resistance to clarithromycin and in one metronidazole resistance was no more detected. Among the nine children treated with a triple therapy including metronidazole, none developed a secondary resistance to metronidazole and one developed a secondary resistance to clarithromycin. CONCLUSION: This study shows the absence of amoxicillin-resistant strains, a high initial clarithromycin-resistant strains level (primary resistance), increasing after a first course of treatment, and for metronidazole a high initial level of resistance not influenced by treatment. Secondary clarithromycin-resistance of Helicobacter pylori strains following the first course of treatment could account for failure of bacterial eradication and suggests the importance of antimicrobial susceptibility.

Omeprazole combined with amoxicillin and clarithromycin in the eradication of Helicobacter pylori in children with gastritis: A prospective randomized double-blind trial.

OBJECTIVES: The aim of this multicenter prospective, randomized, double-blind study was to assess the efficacy of the combination of omeprazole, amoxicillin, and clarithromycin (OAC) for the treatment of Helicobacter pylori gastritis in children. STUDY DESIGN: Seventy-three children with dyspeptic symptoms were included in the trial (mean age 10.8 years; range, 3.3 to 15.4). Patients were randomized to receive OAC or amoxicillin and clarithromycin (AC) for 7 days. H pylori status was assessed before and 4 weeks after eradication treatment, by use of the carbon 13-labeled urea breath test. RESULTS: In intent-to-treat analysis (n = 63), eradication rates were 74.2% (95% CI, 58.7 to 89.6) in the OAC group and 9.4% (95% CI, 0 to 19.5) in the AC group. In per-protocol analysis (n = 53), the eradication rate increased to 80% (95% CI, 64.3 to 95.7), remaining significantly higher than in AC group (10.7%; 95% CI, 0 to 22.2). Resistance of strains to clarithromycin was rare (3/39 = 7.7%) and was not associated with failure of treatment. Adverse events were reported in 24.6% of patients and remained mild. CONCLUSION: This study shows that 1-week OAC triple therapy results in successful eradication of H pylori in 75% of children with gastritis.

Contamination of gastrostomy feeding systems in children in a home-based enteral nutrition program.

BACKGROUND: There are few data concerning the risk of contamination of enteral feeding systems via gastrostomy in children, and none for conditions that pertain to home-based care. METHODS: To investigate the risk of contamination of enteral feeding systems during the home-based care of 20 children receiving gastrostomy tube feeding, five samples were taken for analysis: two samples before the enteral feeding period (gastrostomy, enteral feeding system) and three after this period (gastrostomy, distal giving set, liquid remained in container). Microorganisms were identified and counted. Different factors were studied to elucidate their role in bacterial colonization: acid suppressive therapy, gastrostomy tube or button, hanging feeding time, rate of enteral feeding, gastric pullulation and retrograde contamination, manipulation error, and use of open or closed enteral feeding systems. RESULTS: Overgrowth was defined as a microorganismal load exceeding 10(4) colony-forming units (cfu)/mL. Overgrowth was present in 85% of gastrostomy samples before enteral nutrition started. Most microorganisms belonged to gastric flora. Some bacteria had an environmental origin or derived from cutaneous flora. Forty-five percent of the lines showed overgrowth at the end of enteral nutrition period, mainly with the same microorganism found in the gastrostomy. Closed enteral bags remained sterile, even if manipulation error occurred. Duration, rate of enteral feeding, and acid suppression treatment were not risk factors for overgrowth. CONCLUSIONS: Retrograde contamination of gastrostomy feeding systems occurs frequently. The preferential use of closed enteral feeding systems is recommended for home-based enteral nutrition programs.

[Bacterial epidemiological study of acute otitis media in children observed at home in the Nord Pas-de-Calais region]. / Etude de l'épidémiologie bactérienne de l'otite moyenne aiguë de l'enfant observée en ville dans la région Nord Pas-de-Calais.

BACKGROUND: The aim of this work is the study of the bacteriologic epidemiology of acute otitis media in infants observed at home in Nord Pas-de-Calais area, and the analysis of bacteria associated to recurrent otitis and clinical failure. OBSERVATIONS: A total of 295 specimens of ear pus specimens were collected from children (mean age: 18 months; average: one month-12 years). Pneumococcus strains were isolated from 52% of samples and 80% of these showed resistance to penicillin. H. influenzae was found in 35% of specimens and the half produced a beta lactamase. Pneumococcus is the predominant pathogen isolated in prolonged otitis media, while H. influenzae is preferentially found during recurrent otitis media. The main bacteriologic cause of failure traitement was penicillin-intermediate or -resistant pneumococci. The therapy administered 48 to 72 hours before collection of ear pus sample in therapeutic failure was ineffective (oral cephalosporins or macrolides), or administered to low dosage (50 mg/kg/j). CONCLUSION: Our results demonstrate, in opposition to other studies, Streptococcus pneumoniae as the most frequent pathogen in acute otitis media. They also show the excellent correlation between antibiotic therapy and clinical failures.

Evaluation of a Helicobacter pylori stool antigen test for the diagnosis and follow-up of infections in children.

The aim of this study was to evaluate the performance of a newly developed enzyme immunoassay kit (HpSA) for detecting Helicobacter pylori antigens in the stool of children. This study was comprised of 58 children referred to various endoscopy units for evaluation of gastrointestinal symptoms and upper gastroduodenal endoscopy and 11 children for post-therapy follow-up. In the first group, 23 children were diagnosed as positive for Helicobacter pylori using bacteriological and/or histological methods. Stool antigens were detected in 20 of these positive patients, for a sensitivity of 86.9% and a negative predictive value of 91.9%. Since only one false-positive reaction was observed with the HpSA kit, the specificity was 97.1% and the positive predictive value 95.2%. Results obtained for post-therapy follow-up were also promising. The HpSA assays were negative for the eight children whose infections were eradicated after therapy, and a positive result was obtained for two of three patients who had a persistent infection.

[Comparative antibacterial activity of cefotaxime, ceftazidime and cefepime with regard to different strains of Enterobacter aerogenes selected for their resistance to third generation cephalosporins]. / Activité antibactérienne comparative du céfotaxime, de la ceftazidime et du céfépime vis-à-vis de différentes souches d'Enterobacter aerogenes sélectionnées pour leur résistance aux céphalosporines de troisième génération.

After being confronted with the isolation in our laboratory of numerous antibiotic-multiresistant Enterobacter aerogenes strains, we studied the in vitro antimicrobial activity of cefotaxime, ceftazidime, and cefepime alone or in association with sulbactam. For that, we selected 67 isolates according to their low level of susceptibility to cefotaxime. First, we deduced from a synergy test in presence of clavulanic acid and cloxacillin the production of an extended spectrum beta-lactamase (ESBL) and/or an overproduction of a chromosomal cephalosporinase. Three groups of strains were thus defined: one group of ESBL strains, another group of overproducing strains of chromosomal cephalosporinase, and a last group that produced the two types of enzymes. Minimal inhibitory concentrations (MICs) of each cephalosporin alone or in presence of 8 mg/L of sulbactam, gentamicin or amikacin were measured. Our results demonstrated the best activity of cefepime: MICs were low with a value inferior to 4 mg/L independently of the type of beta-lactamase. They were lower than 0.5 mg/L in presence of sulbactam against ESBL-producing strains. The cephalosporins could be used in association with aminoglycosides according to their susceptibility.

Comparison of iron uptake in different Helicobacter species.

Comparison of iron uptake of four Helicobacter species (Helicobacter pylori, Helicobacter felis, Helicobacter acinonyx, and Helicobacter mustelae), associated with various degrees of gastritis in their respective host, with five other species which colonize the intestinal tract of various animals (Helicobacter fennelliae, Helicobacter cinaedi, Helicobacter muridarum, Helicobacter bilis, and Helicobacter hepaticus), demonstrated that the iron acquisition system differed according to the ecological niche of the organism. Gastric Helicobacter, except for H. pylori, which used iron from human lactoferrin, were nonsiderophore-producing organisms and were only able to obtain iron from heme and hemoglobin. Nongastric Helicobacter produced siderophores and were able to use for growth a wide range of iron sources (bovine and human lactoferrin and transferrin, heme, hemoglobin).