Gérard Lenoir

Mycobacterium abscessus and children with cystic fibrosis.

We prospectively studied 298 patients with cystic fibrosis (mean age 11.3 years; range 2 months to 32 years; sex ratio, 0.47) for nontuberculous mycobacteria in respiratory samples from January 1, 1996, to December 31, 1999. Mycobacterium abscessus was by far the most prevalent nontuberculous mycobacterium: 15 patients (6 male, 9 female; mean age 11.9 years; range 2.5–22 years) had at least one positive sample for this microorganism (versus 6 patients positive for M. avium complex), including 10 with >3 positive samples (versus 3 patients for M. avium complex). The M. abscessus isolates from 14 patients were typed by pulsed-field gel electrophoresis: each of the 14 patients harbored a unique strain, ruling out a common environmental reservoir or person-to-person transmission. Water samples collected in the cystic fibrosis center were negative for M. abscessus. This major mycobacterial pathogen in children and teenagers with cystic fibrosis does not appear to be acquired nosocomially.

In vitro prediction of stop-codon suppression by intravenous gentamicin in patients with cystic fibrosis: a pilot study.

BackgroundCystic fibrosis (CF) is caused by mutations in the gene encoding the cystic fibrosis transmembrane conductance regulator (CFTR) protein, which acts as a chloride channel activated by cyclic AMP (cAMP). The most frequent mutation found in 70% of CF patients is F508del, while premature stop mutations are found in about 10% of patients. In vitro aminoglycoside antibiotics (e.g. gentamicin) suppress nonsense mutations located in CFTR permitting translation to continue to the natural termination codon. Pharmacologic suppression of stop mutations within the CFTR may be of benefit to a significant number of patients. Our pilot study was conducted to determine whether intravenous gentamicin suppresses stop codons in CF patients and whether it has clinical benefits.MethodsA dual gene reporter system was used to determine the gentamicin-induced readthrough level of the most frequent stop mutations within the CFTR in the French population. We investigated readthrough efficiency in response to 10 mg/kg once-daily intravenous gentamicin perfusions in patients with and without stop mutations. Respiratory function, sweat chloride concentration, nasal potential difference (NPD) and CFTR expression in nasal epithelial cells were measured at baseline and after 15 days of treatment.ResultsAfter in vitro gentamicin incubation, the readthrough efficiency for the Y122X mutation was at least five times higher than that for G542X, R1162X, and W1282X. In six of the nine patients with the Y122X mutation, CFTR immunodetection showed protein at the membrane of the nasal epithelial cells and the CFTR-dependent Cl- secretion in NPD measurements increased significantly. Respiratory status also improved in these patients, irrespective of the gentamicin sensitivity of the bacteria present in the sputum. Mean sweat chloride concentration decreased significantly and normalised in two patients. Clinical status, NPD and sweat Cl- values did not change in the Y122X patients with no protein expression, in patients with the other stop mutations investigated in vitro and those without stop mutations.ConclusionSuppression of stop mutations in the CFTR gene with parenteral gentamicin can be predicted in vitro and is associated with clinical benefit and significant modification of the CFTR-mediated Cl- transport in nasal and sweat gland epithelium.

Glucose tolerance and insulin secretion, morbidity, and death in patients with cystic fibrosis.

OBJECTIVES To describe the history, mechanisms, and consequences of cystic fibrosis (CF)-related diabetes, from childhood to early adulthood. STUDY DESIGN Pancreatic beta-cell function was estimated from the plasma insulin/glucose ratios during oral glucose tolerance test (total area under the curve and deltaI(30-0min)/G(30min), homeostasis model assessment [HOMA]%B), insulin sensitivity with the HOMA%S index, in 237 children with CF (109 boys, 128 girls). Progression of glucose metabolism abnormalities was evaluated by analysis for interval censored data; rates of pulmonary transplantation and death by Kaplan-Meier analysis. RESULTS Impaired glucose tolerance was found in 20% of patients at 10 years, 50% at 15 years, 75% at 20 years, 82% at 30 years; for diabetes, >20% at 15 year, 45% at 20 years, 70% at 30 years; for insulin treatment, 30% at 20 years, 40% at 30 years. Early impairment was associated with lower survival rates and higher rates of lung transplantation. The area under the curve(glucose) correlated with decreased body mass index and height. Decrease in early insulin secretion (deltaI(30-0min)/G(30min)) was associated with impaired glucose tolerance, in all estimates of insulin secretion with diabetes. HOMA%S did not differ between the groups. Increased inflammation correlated with insulin resistance and impaired glucose tolerance. CONCLUSIONS CF-related diabetes, mainly because of beta-cell deficiency, is frequent early in life and associated with impaired nutritional state and growth, increased rates of terminal respiratory failure, and death.

In vivo correlates for Streptococcus pneumoniae penicillin resistance in acute otitis media.

Eighty-four children suffering from acute otitis media caused by Streptococcus pneumoniae were treated prospectively with cefuroxime axetil suspension (30 mg/kg of body weight twice daily for 8 days). The high incidence of isolates with decreased susceptibilities to penicillin (42 of 84 isolates) allowed us to establish a relationship between clinical success and the penicillin MICs for pneumococcal isolates. It was found that cefuroxime axetil is clinically effective in the treatment of acute otitis media caused by penicillin-susceptible and penicillin-intermediate strains of S. pneumoniae. The results indicate that the risk of treatment failure with cefuroxime axetil was increased in children with otitis media caused by S. pneumoniae when the penicillin MIC were greater than or equal to 2 mg/liter.

Evaluation of nasopharyngeal cultures for bacteriologic assessment of acute otitis media in children.

BACKGROUND The recent emergence of penicillin-resistant Streptococcus pneumoniae, particularly in acute otitis media (AOM), has increased interest in the development of noninvasive procedures that might help to predict the bacterial etiology of this condition. We conducted an open multicenter study to evaluate the predictive value of the nasopharyngeal (NP) sampling in children with AOM by comparing the bacteriologic results of NP cultures with those of pus collected by myringotomy in the same patients. METHODS The NP secretions and the pus obtained by myringotomy were collected concomitantly in 354 children younger than 6 years of age with clinical signs of AOM. The clinical usefulness of NP culture was determined by calculating its sensitivity and specificity, and especially its positive and negative predictive values for the three main pathogens responsible for AOM, Haemophilus influenzae, S. pneumoniae and Moraxella catarrhalis. RESULTS A positive NP culture was found to have little predictive value for H. influenzae (52%), S. pneumoniae (43%) and M. catarrhalis (19%). In contrast the negative predictive value of NP cultures was much greater and was accompanied by negative middle ear fluid cultures in more than 95% of children, especially for S. pneumoniae. Furthermore the incidence of beta-lactamase-producing strains of H. influenzae at both sampling sites was similar (30 and 35%, respectively), as was the incidence of penicillin-resistant S. pneumoniae (50 and 54%). CONCLUSION It appears that the correlation between results of NP and middle ear fluid cultures in children with AOM is too weak to allow NP culture to be recommended for the bacteriologic documentation of this disease. However, these results should not overshadow the considerable epidemiologic value of NP cultures, particularly with reference to the monitoring of pneumonococcal susceptibility in children. The collection of NP cultures should therefore be promoted for their collective epidemiologic value.

Elevated Plasma 1,25-Dihydroxyvitamin D Concentrations in Infants with Hypercalcemia and an Elfin Facies

We measured plasma concentrations of 1,25-dihydroxyvitamin D (1,25-(OH)2D) in the course of a 6-to-37-month survey of four children with hypercalcemia and an elfin facies (Williams syndrome). Levels of 1,25-(OH)2D were elevated (160 to 470 pg per milliliter) during the hypercalcemic phase of the disease, when the children were five to nine months old, and they decreased thereafter. Plasma 1,25 (OH)2D levels were higher than those found in three children (16 to 60 months old) with the elfin facies syndrome and no hypercalcemia (42 to 71 pg per milliliter) and eight children (1 to 36 months old) with hypercalcemia and no dysmorphy (12 to 140 pg per milliliter), including two children with vitamin D intoxication. Hypercalcemia in the three children with elfin facies was controlled by a low-calcium diet. Serum calcium levels fell to the normal range, and plasma 1,25-(OH)2D levels were normal for age (18 to 105 pg per milliliter) at 14 to 47 months of age, even after appropriate therapy had been discontinued. These observations suggest that hypercalcemia may be the consequence of abnormal synthesis or degradation of 1,25-(OH)2D in children with the elfin facies syndrome.

Efficacy, safety, and local pharmacokinetics of highly concentrated nebulized tobramycin in patients with cystic fibrosis colonized with Pseudomonas aeruginosa.

AbstractBackground and aim Progressive respiratory failure due to Pseudomonas aeruginosa colonization is the most significant morbidity in patients with cystic fibrosis (CF). This trial was designed to investigate the efficacy and safety of a highly concentrated (300mg/4mL) tobramycin solution for inhalation (TSI) [Bramitob®] in patients with CF and P. aeruginosa infection. Methods Fifty-nine patients were randomized to receive a 4-week treatment with tobramycin or placebo administered twice daily via the Pari LC Plus® nebulizer and Pari TurboBoy™ compressor, followed by a 4-week run-out phase. Pulmonary function (forced expiratory volume in 1 second [FEV1], forced vital capacity [FVC], and forced expiratory flow at the midportion of vital capacity [FEF25–75%]), P. aeruginosa susceptibility, microbiologic results, and in vitro minimum inhibitory concentration for 90% of strains (MIC90) were the efficacy outcome measures, while safety was monitored by the recording of adverse events, audiometry (bone conduction at 250–8000Hz frequency), laboratory tests, physical examination and general health condition. The concentration of tobramycin attained in sputum was measured in a cohort of 21 patients. Results FEV1 significantly increased from baseline in the tobramycin group compared with no change in the placebo group: the absolute difference between groups (intent-to-treat population) of predicted normal was 13.2% at week 2 (p = 0.002) and 13.3% at week 4 (p = 0.003). Significant differences in favor of the tobramycin group were also observed for FVC and FEF25–75%. The microbiologic results at the end of the treatment period (P. aeruginosa-negative culture, persistence, superinfection) showed a significantly better outcome in the tobramycin group compared with placebo (p = 0.033). The effects of tobramycin on pulmonary function and microbiology were not maintained at the end of the run-out phase.Mean sputum concentrations of tobramycin after the first dose (695.6 ± 817.0 µg/mL) were similar to those measured after the last dose (716.9 ± 799 µg/mL) and were superior to the detected specific MIC90.The proportion of patients with drug-related adverse events was lower in the tobramycin group and no signs of renal or auditory toxicity were observed. Conclusions The 4-week administration of a highly concentrated TSI significantly improved pulmonary function and microbiologic outcome compared with placebo and was well tolerated. The results of this study should be confirmed in further long-term trials in larger populations.

In cystic fibrosis homozygotes and heterozygotes, neutrophil apoptosis is delayed and modulated by diamide or roscovitine: evidence for an innate neutrophil disturbance.

Cystic fibrosis (CF) is a chronic inflammatory lung disease characterized by polymorphonuclear neutrophil (PMN)-dominated airway inflammation. Defective apoptosis might explain PMN persistence at these inflammation sites. We previously reported that in CF patients PMN underwent delayed apoptosis, which was not always related to their infectious state and independent of the type of CF transmembrane regulator (CFTR) mutation. To understand the role of infection and PMN apoptosis in CF, PMN apoptosis was investigated in CF parents who are obligate heterozygotes for the CFTR mutation but without chronic bacterial infection. They also demonstrated delayed PMN apoptosis compared with healthy controls, as assessed by annexin-V labeling and caspase-3 cleavage. Diamide, a direct thiol-oxidizing agent, potentiated PMN apoptosis in controls and CF patients, resulting in similar levels of constitutive and Fas-potentiated apoptosis. The cyclin-dependent kinase inhibitor roscovitine provided another approach to restore normal PMN apoptosis. However, the selective CFTR inhibitor CFTRInh172 did not affect PMN apoptosis in control subjects. Apparently, the dysregulation of CF PMN is not only a consequence of the chronic infectious state in CF children but might also be related to CF ‘intrinsic’ factors. Restoration of normal PMN apoptosis by cellular redox modulation or roscovitine opens new research avenues to decrease PMN-mediated inflammation in CF.

Use of 16S rRNA Gene Sequencing for Identification of Nonfermenting Gram-Negative Bacilli Recovered from Patients Attending a Single Cystic Fibrosis Center

ABSTRACT During 1999, we used partial 16S rRNA gene sequencing for the prospective identification of atypical nonfermenting gram-negative bacilli isolated from patients attending our cystic fibrosis center. Of 1,093 isolates of nonfermenting gram-negative bacilli recovered from 148 patients, 46 (4.2%) gave problematic results with conventional phenotypic tests. These 46 isolates were genotypically identified as Pseudomonas aeruginosa (19 isolates, 12 patients), Achromobacter xylosoxidans (10 isolates, 8 patients), Stenotrophomonas maltophilia (9 isolates, 9 patients), Burkholderia cepacia genomovar I/III (3 isolates, 3 patients), Burkholderia vietnamiensis (1 isolate), Burkholderia gladioli (1 isolate), and Ralstonia mannitolilytica (3 isolates, 2 patients), a recently recognized species.

6q1 monosomy: a distinctive syndrome

A female infant with a de novo del 6q14q16.2 and five other patients with del 6q1 reported in the literature allow the delineation of a characteristic syndrome, the main features of which are: severe mental retardation, a round face with full cheeks, upslanting palpebral fissures, a short neck, umbilical hernia, malpositioned feet with syndactyly II‐III, and typical dermatoglyphics with an excess of whorls and clinodactyly of the Vth finger.