[Resistance to antibiotics of Staphylococcus aureus responsible of osteoarticular infections]. / Résistance aux antibiotiques des Staphylococcus aureus responsables d'infections ostéoarticulaires.

Osteo-articular infections represent the majority of invasive Staphylococcus aureus infections in children. It is demonstrated that, independently of the resistance or susceptibility to methicillin, the production of Panton-Valentine leukocidin (PVL) by S. aureus enhanced the severity of the disease. However, an increase of the rate of community acquired methicillin-resistant S. aureus (CA-MRSA) has been reported in osteo-articular infections. These CA-MRSA are the most often susceptible to the other antibiotics. SCCmec elements of type IV or V associated with the PVL coding genes seem to be molecular markers of CA-MRSA. The risk factors of acquisition of these strains are the young age of children and the overcrowding. It is now established that CA-MRSA are pathogens present all over the world. It thus became necessary to look after the epidemiology of these virulent strains.

[Role of thiamphenicol in the treatment of community-acquired lung infections]. / Place du thiamphénicol dans le traitement des pneumopathies communautaires.

Streptococcus pneumoniae and Haemophilus influenzae are the two main pathogens responsible for bacterial respiratory tract infections. Their antimicrobial susceptibility to antibiotics like beta-lactams, macrolides or fluoroquinolones has been largely studied, while it remains less known to other antibiotics like thiamphenicol, erythromycin, cotrimoxazole or tetracycline, often used in developing countries due to their availability. In this study, the activity of chloramphenicol and thiamphenicol on different respiratory tract pathogens was found to be equivalent. However, thiamphenicol was better in detecting resistant organisms. One hundred S. pneumoniae among which 69% had reduced susceptibility to penicillin (PRSP) and 87 H. influenzae isolates, 39.1% producing beta-lactamase, were recovered from sputum cultures in children. All H. influenzae and all penicillin susceptible S. pneumoniae strains were sensitive to thiamphenicol. Susceptibility of penicillin sensitive S. pneumoniae to erythromycin, cotrimoxazole and tetracycline was 70.9%, 83.9%, and 90.3% respectively. Susceptibility of PRSP to thiamphenicol, erythromycin, cotrimoxazole and tetracycline was 68.1%, 7.2%, 17.4% and 44.9% respectively. Thiamphenicol and chloramphenicol are still active against respiratory pathogens.

In vitro combined bactericidal activity of cefpirome and glycopeptides against glycopeptides and oxacillin-resistant staphylococci.

Infections caused by coagulase-negative staphylococci are becoming increasingly important, particularly those of nosocomial origin, as the organisms are frequently multi-resistant. New antimicrobial strategies are needed. The bactericidal activity of a combination of cefpirome with either vancomycin or teicoplanin against 12 strains of methicillin-resistant staphylococci with a decreased susceptibility to teicoplanin was determined in vitro by a time killing method. Strains Mu3 and Mu50 of Staphylococcus aureus were also studied. Cefpirome (0.125-0.5 x MIC) combined with vancomycin (0.25-1 x MIC) or teicoplanin (0.125-1 x MIC) acted synergically against 12 isolates over 18 h in most cases. A synergistic killing effect was also observed with the Mu3 and Mu50 strains of glycopeptide-intermediate S. aureus but over a longer period.

[Nosocomial bacteremias in pediatrics]. / Bactériémies nosocomiales en pédiatrie.

OBJECTIVES: To identify pathogenic microorganisms responsible for hospital-acquired bloodstream infections and to evaluate the associated risk factors in pediatric units, in a case-control study over 30 months from January 1st 1997 to June 30th 1999. RESULTS: Forty-six of 855 (5.4%) positive blood cultures were attributed to nosocomial infections. They were related to 32 infectious episodes in 28 patients hospitalized for more than 48 hours. The incidence rate was 0.11 per 100 admissions. Gram-positive cocci (n = 14; 38.8%) were the most frequently isolated pathogens (7 cases of Staphylococcus aureus, 5 of coagulase-negative staphylococci), followed by enterobacteria (n = 9; 25%), Pseudomonas aeruginosa (n = 5; 13.8%) and yeasts (n = 5; 13.8%). The major risk factors for hospital-acquired bloodstream infections were: length of stay before positive blood culture (32 +/- 51 days in cases vs 15 +/- 43 days in controls, p < 0.01), presence of central venous catheter [odds ratio (OR): 6.05, 95% confidence interval (CI): 1.87-20.42], number of days with central venous catheter (p < 0.001) and parenteral nutrition (OR: 9.44, 95% CI: 2.03-50.05). CONCLUSION: Central venous catheter use, length of stay, parenteral nutrition and particularly intravenous lipids are major risk factors for the acquisition of bloodstream infection in hospitalized children.

[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.

[Impact of bacterial resistance on severe infections]. / Impact de la résistance bactérienne sur les infections graves.

Since many years, the antimicrobial resistance increases as well as for community-acquired as for nosocomial infections. Antibiotic-resistant pneumococci are neither more nor less virulent susceptible strains. Except for immunocompromised patients, the outcome of penicillin-resistant pneumococcal infections have been similar to those in patients who are infected by susceptible ones. Current levels of S. pneumoniae resistance to penicillin and cephalosporin are not associated to an increase in mortality in children with meningitis if adequate doses of antibiotics are given. Because empiric therapy has changed, antibiotic resistance has not been associated with increased mortality. This statement can be extended to Meningococcus, for which 32 to 50% of the strains have a decreased susceptibility to penicillin. For nosocomial infections, S. aureus is the main studied pathogen. Several studies report that in patients with severe diseases (bacteremia or pneumonia) methicillin resistance of S. aureus had no significant impact on patient outcome after adjustment for different confounders. The main risk factor for mortality is the severe underlying diseases rather than the resistance as well for methicillin--resistant S. aureus, as for vancomycin resistant enterococci, Klebsiella with extended spectrum beta lactamase and Enterobacters. Recommendations for controlling epidemiologic surveillance, using barrier precautions and limiting the use of antibiotics as well in the hospital as in the community must be undertaken.

Clarithromycin resistance and eradication of Helicobacter pylori in children.

Outcome of Helicobacter pylori infection was analyzed in 61 children treated with a triple therapy including clarithromycin. Bacterial eradication was obtained in all children with clarithromycin-susceptible strains but not in children with clarithromycin-resistant ones (P = 0.0001). H. pylori antimicrobial susceptibility is mandatory before choosing a treatment, and clarithromycin should be avoided in case of resistance.

High levels of resistance to metronidazole and clarithromycin in Helicobacter pylori strains in children.

The aim of the study was to evaluate the prevalence of resistance to amoxicillin, metronidazole, and clarithromycin before treatment of Helicobacter pylori infection in children and to assess the evolution of resistance with time. The study was carried out between 1994 and 1999 with 150 H. pylori-positive children through gastric culture (antimicrobial susceptibility) and histology. All cultured H. pylori strains were sensitive to amoxicillin, 64 (43%) were resistant to metronidazole, 32 (21%) were resistant to clarithromycin, and 14 (9%) were resistant to both metronidazole and clarithromycin. The overall prevalence of resistance to metronidazole and clarithromycin did not change significantly with time. The study highlights the generalized high-level and stable metronidazole and clarithromycin resistance of H. pylori strains from children.

Immunoblotting and serology for diagnosis of Helicobacter pylori infection in children.

BACKGROUND: The easiest way to identify the presence of current or past Helicobacter pylori infection is to test for antibodies. The aim of this study was to compare an enzyme-linked immunosorbent assay (ELISA) technique based on the detection of IgG antibodies directed against a global antigenic preparation with immunoblotting based on the analysis of IgG antibody reactivity to separate proteins. METHODS: Sera were collected from 80 children (mean age, 9.9 +/- 4.3 years). The reference tests were microbiologic and histologic examination of gastric biopsies obtained at upper endoscopy. RESULTS: The immunoblotting was more sensitive (100%) and specific (88%) than ELISA (96 and 79%, respectively) in the evaluation of H. pylori infection in children. Its positive predictive value was 92%, and its negative predictive value was 100%. The best performance index of immunoreactive bands to detect antibodies was obtained with the 26-kDa (88.7%), 30-kDa (77.5%) and 19.5-kDa (70%) antigens. Antibodies by immunoblot technique against the CagA antigen were present in 43.1% of children. CONCLUSION: Immunoblotting is highly sensitive and more specific than ELISA in children and provides additional information about the full serologic profile. Immunoblotting may therefore be a useful complement to serology, particularly in cases with doubtful ELISA results.

In-vitro bactericidal activity of cefpirome and cefamandole in combination with glycopeptides against methicillin-resistant Staphylococcus aureus.

The bactericidal activity in vitro of cefpirome plus either vancomycin or teicoplanin was compared with that of a cefamandole-vancomycin combination against ten clinical isolates of homogeneous methicillin-resistant Staphylococcus aureus. Cefpirome (0.125 x MIC) combined with vancomycin (0.5-2 x MIC) or teicoplanin (0.5-4 x MIC) acted synergically against the ten isolates. Similar effects were observed with the cefamandole-vancomycin combination, except that for one isolate, higher cefamandole concentrations (0.25-1 x MIC) were required.

[Bacteriologic surveillance of nosocomial septicemia and bacteremia in a pediatric hospital]. / Surveillance bactériologique des septicémies et bactériémies nosocomiales dans un hôpital pédiatrique.

BACKGROUND: Nosocomial bloodstream infections in pediatrics are an important cause of morbidity and mortality. To identify pathogens causing nosocomial bloodstream infections, evaluate associated risk factors and take preventive measures, we conducted a prospective study from January 1995 to December 1995 at Saint-Vincent-de-Paul Hospital (Paris). PATIENTS AND RESULTS: All patients hospitalized more than 48 hours were included in the study. During this period, we recorded 21 bloodstream infections in 20 children. The incidence rate of nosocomial bloodstream infection was 1/1,000 admissions. Sixteen children were hospitalized in surgery, three in medical intensive care unit; the median day onset of infection was approximately 20 days. Recorded risk factors were: surgery, invasive procedures, central catheterization, bladder catheters, parenteral nutrition, device, endotracheal tube, antibiotic therapy before infection. The number of risk factors ranged from zero to six per patient. The most common isolated pathogens were in ten cases Gram positive cocci: five methicillin-sensible Staphylococcus aureus, four methicillin-resistant coagulase-negative staphylococci and one Streptococcus milleri. Other bacteria were seven enterobacteria, three Pseudomonas sp and three Candida sp. In 11 cases, the same bacteria as in bloodstream infection could be found: in three urine samples, in two tracheal samples, in two gastro-intestinal samples, two puncture sites, one device, and one umbilical catheter. CONCLUSION: In our study, 6.2% of positive blood culture were due to a nosocomial infection. We confirm the importance of Gram positive cocci, and particularly of methicillin-resistant coagulase negative staphylococci.

[Prevalence of Helicobacter pylori infection in children according to their age. A retrospective study]. / Prévalence de l'infection à Helicobacter pylori chez l'enfant en fonction de l'âge: étude rétrospective.

UNLABELLED: The aim of this study was to evaluate the prevalence of H pylori infection in a Parisian children population. PATIENTS AND METHODS: During a 3-year period, H pylori infection was investigated in 623 children admitted to our hospital. Children were enrolled into two groups; either a symptomatic children group with clinical gastritis manifestations as infant colics or recurrent abdominal pain for more than 3 months in whom H pylori infection was suspected, or a control children group with growth retardation of more than -2 standard deviation (SD). Ethnic origin for all enrolled children was identified. A written parental consent was obtained for all children. H pylori infection was identified by enzyme-linked immunosorbent assay (ELISA) (Cobas Core Roche, IgG, 2nd generation, Roche, France). RESULTS: H pylori infection was identified in 99 children out of 623 (15.8%). There was no difference between the two groups of children for age, sex, ethnic origin and prevalence of H pylori infection. The prevalence of H pylori infection was widely dependent on age and rose regularly with an annual acquisition rate of 2.1%. The prevalence of this infection varied from 1.8% during the first year of life to 30% in 15-year-old children. CONCLUSION: The latter prevalence is quite similar to that found in adults, suggesting that infection might occur in early life.

[Nosocomial urinary tract infections: retrospective study in a pediatric hospital]. / Infections urinaires nosocomiales: étude rétrospective dans un hôpital pédiatrique.

Urinary tract infections (UTI) are the most frequent nosocomial infection in the adult, yet very few data are available concerning these infections in children. In a retrospective 1-year study in a paediatric hospital, we analysed the incidence of nosocomial UTI and the characteristics of the affected children. The incidence was of 1.97/1,000 admissions which represented 6.8% of all UTI diagnosed by the microbiology laboratory. Most cases were in surgery and neurology wards. The frequency was inversely proportional to the age, with 50% of children being less than 2 years old. Pathogens most frequently isolated were E coli (39%), Pseudomonas sp (12.1%) and Enterococcus sp (12.1%). When compared with the organisms found in all the urine cultures during the same period, two organisms were more frequently found in nosocomial urinary tract infections: Pseudomonas sp and Candida sp. Most patients presented one or more risk factors, mainly:bladder catheterisation (41.4%), prior antibiotic therapy (62%), cerebral palsy (6.9%). No bacteriema was observed. The diagnosis of nosocomial UTI must be interpreted with caution and needs close collaboration between microbiologists and paediatricians. These infections increase the cost of hospitalisation, but only exceptionally do they present with complications. Some risk factors are inherent in hospital conditions, but others can be reduced by improving hand washing or by changing catheterisation practices.

GABA modulates cytotoxicity of immunocompetent cells expressing GABAA receptor subunits.

C57 black mouse splenic T lymphocytes effector cells were co-cultivated with Balb/c mouse splenic cells for sensitization; P815 DBA mouse mastocytoma target cells were then added and specific T cell-dependent cytotoxicity determined. This cytotoxicity increased after gamma-aminobutyric acid (GABA) treatment of the sensitized effectors, but decreased after GABA treatment of the targets. These GABA effects seemed to be specific since they were partially mimicked by linear but not ramified GABA analogues. Furthermore, they were likely mediated by GABAA receptor since GABAA receptor subunit mRNAs and protein could be demonstrated in effector or target immune specific cells, suggesting that under yet to be defined circumstances, GABA may affect T cell functions.