Pediatric osteoarticular infections caused by Streptococcus pneumoniae before and after the introduction of the heptavalent pneumococcal conjugate vaccine.

Streptococcus pneumoniae is an uncommon cause of osteoarticular infections (OAI) in children. The objective of this study was to investigate the clinical and laboratory characteristics of pneumococcal OAI before and after the introduction of the heptavalent pneumococcal conjugate vaccine (PCV7). Data were retrospectively collected from children aged <16 years who were hospitalized for pneumococcal OAI between 1997 and 2007 in four Parisian teaching hospitals. Forty-three children were included (32 with arthritis and 11 with osteomyelitis) and the median age of these children was 12.5 months (range 3 months to 14 years). Serotypes were available for 19/43 strains (44 %) from 1997 onwards and for 12/13 strains (92 %) from 2005 onwards. Seven unvaccinated children were infected with vaccine serotypes and we observed only one vaccine failure. After the introduction of PCV7, we noted an increase in short-term complications and the emergence of serotype 19A, which was penicillin-intermediate in 86 % of cases. After PCV7 introduction, serotype 19A was the most frequent serotype implicated in pediatric pneumococcal OAI. The 13-valent pneumococcal conjugate vaccine introduced in France in June 2010 should cover the emerging serotype.

A new highly discriminatory multiplex capillary-based MLVA assay as a tool for the epidemiological survey of Pseudomonas aeruginosa in cystic fibrosis patients.

Multiple locus variable number of tandem repeats (VNTR) analysis (MLVA) has been shown to provide a high level of information for epidemiological investigations and the follow-up of Pseudomonas aeruginosa chronic infection. In the present study, an automatized MLVA assay has been developed for the analysis of 16 VNTRs in two multiplex polymerase chain reactions (PCRs), followed by capillary electrophoresis. The result in the form of a code is directly usable for clustering analyses. This MLVA-16(Orsay) scheme was applied to the genotyping of 83 isolates from eight cystic fibrosis patients, demonstrating that the same genotype persisted during eight years of chronic infection in the majority of cases. Comparison with pulsed-field gel electrophoresis (PFGE) analysis showed that both methods were congruent, MLVA providing, in some cases, additional informativity. The evolution of strains during long-term infection was revealed by the presence of VNTR variants.

Salmonella enterica serotype Gambia with CTX-M-3 and armA resistance markers: nosocomial infections with a fatal outcome.

We report two cases of bacteremia caused by the Salmonella enterica serotype Gambia in our children's hospital, with one fatal outcome. The isolates showed indistinguishable genotypes and infrequent resistance markers: CTX-M-3 extended-spectrum ß-lactamase and armA methyltransferase. This is the first report of S. Gambia exhibiting CTX-M-3 and armA markers involved in serious infections.

[Salmonella enterica serovar typhimurium infection presenting as a retrocecal mass in an 8-year-old child]. / Infection àSalmonella enterica sérotype typhimurium révélée par une masse rétrocaecale chez une enfant âgée de 8 ans.

Minor salmonellosis is due to Gram-negative bacilli, which usually cause enterocolitis with potentially severe complications. We report on a case of a clinically uncommon presentation of Salmonella enterica serovar typhimurium infection in an 8-year-old child who presented with acute abdominal pain. We discuss clinically uncommon presentations of salmonella disease in children, as well as its pathology and radiology.

[Description and investigation of an outbreak of extended-spectrum beta-lactamase producing Escherichia coli strain in a neonatal unit]. / Description et investigation d'une épidémie nosocomiale de colonisations et d'infections à Escherichia coli producteur d'une bêta-lactamase à spectre étendu dans un service de néonatologie.

An outbreak of colonization and infection with an Escherichia coli strain producing extended-spectrum beta-lactamase (ESBL) occurred in a neonatal unit : a high rate of cases was observed, 27/59 neonates were colonized : one of them developed meningitis with favourable outcome and another baby developed conjunctivitis. Despite intensive efforts to control the outbreak by standard methods of hand hygiene, patients screening and isolation, the spread was uncontrolled and the unit was closed to all admission in order to stop the outbreak. The investigation was not able to identify a single outbreak's source. Emergence and spread of ESBL producing E. coli strains from community and hospital acquired infections are a significant public health problem with difficult choice of treatment for serious infections.

[Coagulase-negative staphylococcal osteomyelitis in preterm infants: a proposal for a diagnostic procedure]. / Ostéomyélites à staphylocoque coagulase négative chez le prématuré : proposition de démarche diagnostique.

Acute osteomyelitis, although a rare complication in neonates, is a diagnostic and therapeutic challenge. Successful treatment to avoid functional sequelae depends on early recognition of infection and rapid initiation of therapy. Although Staphylococcus aureus is the most common causative agent, coagulase-negative Staphylococcus (CONS), well known for bloodstream infection, can be involved in neonatal osteomyelitis. Risk factors of osteomyelitis include prematurity and invasive procedures, such as long-term central venous catheterization. We report on 3 cases of acute CONS osteomyelitis in preterm infants presenting with prolonged CONS bacteremia. Bacteremia persisted despite antibiotic treatment in accordance with antibiograms and despite removal of the intravascular device. All catheter cultures were negative and osteomyelitis was not located on the limb where the central catheter had been inserted in all cases. Osteomyelitis diagnosis may be difficult in neonates because of the paucity of clinical signs. In our observations, (99m)Tc scintigraphy was the key investigation for diagnosis and detection of multiple sites of bone infection. The place of this investigation is discussed in relation to other imaging techniques. These observations suggest that in the context of persisting CONS bacteremia, a secondary bone infection should be considered. Scintigraphy is a discriminating diagnostic tool.

[Phenotypic and genotypic (randomly amplified polymorphic DNA analysis and multiple-locus variable-number tandem-repeat analysis) charaterization of 96 clinical isolates of Pseudomonas aeruginosa in the F. Bourguiba hospital (Monastir, Tunisia)]. / Caractérisation phénotypique et génotypique (randomly amplified polymorphic DNA analysis et multiple-locus variable-number tandem-repeat analysis) de 96 isolats cliniques de Pseudomonas aeruginosa à l'hôpital F. Bourguiba (Monastir, Tunisie).

AIM OF THE STUDY: Phenotypic and genotypic characterization of 96 clinical isolates of Pseudomonas aeruginosa recovered in a Tunisian teaching hospital during a 16-month period. MATERIALS AND METHODS: All the isolates were characterized by serotyping, antimicrobial susceptibility typing and genotyping with randomly amplified polymorphic DNA (RAPD) analysis and multiple-locus variable-number tandem-repeat analysis (MLVA). RESULTS: Forty-one isolates out of 96 (43%) were recovered from two intensive care units (medical and chirurgical). Most of the isolates (48%) belonged to serotype O:11. Among the 13 antibiotypes, three multidrug resistant ones were mostly observed within the two intensive care units. Genotyping showed 83 RAPD types and 52 MLVA types. Isolates showing the same serotype could show different genotypes. A limited number of clusters was highlighted with MLVA typing, of which an outbreak of nine cases within the surgical intensive care unit. CONCLUSION: Except this outbreak of nine cases, the heterogeneity observed for most of the P. aeruginosa isolates showed that outbreak situations were rare in the F. Bourguiba hospital during the study period. MLVA genotyping is a good tool for genotyping P. aeruginosa clinical isolates.

[Contribution of microbiological methods to the diagnosis of acute bacterial meningitis]. / Apport des examens microbiologiques au diagnostic des méningites bactériennes aiguës.

The most frequent bacteria responsible for acute bacterial meningitis, after the neonatal period, are meningoccoci and pneumococci, very rarely Haemophilus influenzae and Listeria monocytogenes. The microbiological diagnosis is based on cell count, Gram stain, and culture of cerebrospinal fluid. Antigen detection and DNA detection are useful to identify the bacteria in cases of negative cultures, because of the fragility of some bacterial species (meningococci), or a prior antibiotic administration, before a lumbar puncture. Some tests for screening antimicrobial resistances are needed, such as those for detection of resistance to betalactam agents in pneumococcal isolates. Blood cultures, serum samples, skin rash biopsies also contribute to the diagnosis.

[Empyema: bacterial epidemiology and antibiotic resistance]. / Pleuro-pneumopathies : épidémiologie bactérienne et résistances aux antibiotiques.

It is essential to know the epidemiology and resistance to antibiotics of the main pathogens responsible for children empyema because the bacteriological diagnosis is reached in less than half the cases. This diagnosis can be improved when using sophisticated methods of investigation, such as antigens detection, PCR... The main species involved is Streptococcus pneumoniae, then followed by Streptococcus pyogenes, Staphylococcus aureus. The pneumococcal serotypes most often involved in France are 1, 19A, 14 and 3. If some of them remain susceptible to penicillin (1,3), others may be resistant (19A, 14) and the majority are not included in the 7 valent pneumococcal conjugate vaccine.

[Antibiotic treatment of child empyema: lessons from published studies and therapeutic options]. / Antibiothérapie des pleuropneumopathies de l'enfant : quelles leçons tirer des études cliniques publiées et propositions thérapeutiques.

Children empyema pose therapeutic problems for reasons that are not clearly established. The pneumococcus is by far the bacteria most often responsible. There is no clinical study demonstrating the superiority of an antibiotic regimen over another. Even though these studies exist, they would be challenged by the evolution of bacterial resistance that may vary depending on different parameters: antibiotic pressure, vaccination etc. Therefore, it is on the microorganism suspected, the data of bacterial resistance and pharmacokinetics-pharmacodynamic (Pk / Pd) parameters that lead to antibiotic choice. An analysis of these elements can lead to the following proposals. For pneumococcal empyema, intravenous 3rd generation cephalosporin at dose of 100mg/kg/day divided 4 injections IV for cefotaxime or 50mg/kg/day in once a day for ceftriaxone. These doses are likely to be doubled in case of pneumococcus resistant to penicillin. Neither fosfomycine or aminoglycosides have a sufficient activity against pneumococcus to be offered in combination. If an association seems useful, the two best candidates are vancomycin and rifampin. For group A streptococcus empyema, clindamycin in association with is certainly the best choice. The recent evolution of resistance to macrolides should lead to check the susceptibility of the bacteria implicated. If S. aureus is susceptible to meticilline (most often), a M penicillin by parenteral route associated with an aminoglycoside is proposed. Fosfomycine can be an alternative to the aminoglycoside. If S. aureus is meticilline resistant, the association vancomycin and rifampicin seems best suited. When no bacteria has been isolated, the choice against pneumococcus resistant seems most appropriate.

[Use of 16S rRNA gene sequencing for identification of "Pseudomonas-like" isolates from sputum of patients with cystic fibrosis]. / Mucoviscidose: identification des bacilles isolés d'infections bronchiques par séquençage du gène de l'ARN ribosomal 16S.

Since nonfermenting, Gram negative bacilli recovered from patients with cystic fibrosis could be misidentified with phenotypic procedures, we used partial 16S ribosomal RNA gene (16S gene) sequencing to identify these "Pseudomonas-like" isolates. 473 isolates were recovered from 66 patients in 2003. Sequencing was used to identify 29 (from 24 patients) of the 473 isolates, showing unclear results with routine tests. PCR with specific primers was carried out to amplify a 995 bp fragment, which was then sequenced. The sequences were analyzed with GenBank database for species assignment. Phenotypic and genotypic results were concordant for 20/29 isolates (10 Pseudomonas aeruginosa, 5 Burkholderia cepacia, 3 Stenotrophomonas maltophilia, 2 Achromobacter xylosoxidans). However, 3 of the 5 B. cepacia isolates were then identified as Burkholderia multivorans with a PCR-RFLP procedure. Phenotypic misidentification was observed for 9/29 isolates: 4 A. xylosoxidans, 1 P. aeruginosa, 1 Bordetella petrii, 1 Bordetella bronchiseptica, 1 Ralstonia respiraculi and 1 Ralstonia mannitolilytica. Partial 16S gene sequencing improved the identification of "Pseudomonas-like" isolates from cystic fibrosis patients, but the accuracy to distinguish between genomovars of the B. cepacia complex was inadequate.

Piperacillin-tazobactam and netilmicin as a safe and efficacious empirical treatment of febrile neutropenic children.

GOALS OF WORK: We evaluated piperacillin-tazobactam in association with netilmicin (TN) in the early empirical treatment of neutropenic children, as data are limited in number. PATIENTS AND METHOD: In 1996, an observational study was initiated to assess the efficacy and safety of this association, with a glycopeptide (TNG) if needed. The impact on the bacterial ecology of our unit was also observed. Children were treated for hematological malignancy or solid tumor between September 1996 and December 1998 and presented a febrile neutropenia. RESULTS: There were 148 evaluable febrile neutropenic episodes in 104 patients. Median age was 7 years, 55% of the episodes were fever of unknown origin, 22% were clinically documented and 23% microbiologically documented (27 bacteriemia). A glycopeptide was added in 67 episodes. The initial unmodified treatment was successful in 114 episodes (77%): 75/81 episodes in the TN group and 39/67 in the TNG group. For successful episodes, median treatment duration was 6 days. There were 22 febrile recurrences. These patients, as well as initial failures, always responded to a second-line treatment. One child was considered a failure because he developed a skin rash probably due to piperacillin-tazobactam and required another beta-lactamase. CONCLUSION: This study suggests that piperacillin-tazobactam in association with netilmicin presents a satisfactory efficacy and a good tolerance as empirical therapy for febrile neutropenic children. It allowed us to maintain the bacterial ecology of our unit.

Ralstonia paucula (Formerly CDC group IV c-2): unsuccessful strain differentiation with PCR-based methods, study of the 16S-23S spacer of the rRNA operon, and comparison with other Ralstonia species (R. eutropha, R. pickettii, R. gilardii, and R. solanacearum).

Ralstonia paucula (formerly CDC group IV c-2) can cause serious human infections. Confronted in 1995 with five cases of nosocomial bacteremia, we found that pulsed-field gel electrophoresis could not distinguish between the isolates and that randomly amplified polymorphic DNA analysis was poorly discriminatory. In this study, we used PCR-ribotyping and PCR-restriction fragment length polymorphism analysis of the spacer 16S-23S ribosomal DNA (rDNA); both methods were unable to differentiate R. paucula isolates. Eighteen strains belonging to other Ralstonia species (one R. eutropha strain, six R. pickettii strains, three R. solanacearum strains, and eight R. gilardii strains) were also tested by PCR-ribotyping, which failed to distinguish between the four species. The 16S-23S rDNA intergenic spacer of R. paucula contains the tRNA(Ile) and tRNA(Ala) genes, which are identical to genes described for R. pickettii and R. solanacearum.

Epidemiological investigation of Ochrobactrum anthropi strains isolated from a haematology unit.

Ochrobactrum anthropi is an oxidase-producing gram-negative bacillus preferring aqueous environments. It is an opportunist of low pathogenicity with a wide and unpredictable antibiotic resistance. We observed bacteraemia caused by this organism in two immunocompromized patients hospitalized in the same haematology unit and catheter-associated sepsis was recognized within two days. Another isolate was obtained from the stools of a third patient of the same unit. Environmental investigations recovered an isolate from a tap-water sample of the unit. Pulsed-field gel electrophoresis analysis of these four isolates and two others isolates previously found in the same ward, showed identical restriction patterns for the two blood isolates and confirmed that the two bacteraemia were epidemiologically related.

[Nosocomial infections in immunocompromised children]. / Infections nosocomiales chez l'enfant immunodéprimé.

Immunocompromised children are at high risk for developing nosocomial infections which may cause significant morbidity and mortality in this population. In paediatric oncology, reported prevalence of nosocomial infections varies from 10 to 20%. Major predisposing factors are neutropenia, central venous catheter, corticosteroid therapy and hospital construction or renovation for invasive aspergillosis. The management of patients with febrile neutropenia should take into account the previous history of infection and the microbiologic environment of each department. Nowadays, Gram positives infections are predominant, but fungal infections remain a major threat. In organ transplant recipients, wound infections are the main early problems, followed by viral infections often due to the donor CMV seropositivity. In HIV-infected children, nosocomial infections are difficult to define, and can implicate unusual pathogens. In general, adapted preventive infection control strategy warrants prospective studies.

Evolution of the bacteriologic features of persistent acute otitis media compared with acute otitis media: a 15-year study.

OBJECTIVES: To define the epidemiologic features of persistent acute otitis media (PAOM) and modifications of these features during the past 15 years and to investigate for possible differences in bacterial resistance between acute otitis media (AOM) and PAOM. DESIGN: Retrospective patient series. SETTING: Academic tertiary care center. PATIENTS AND METHODS: Persistent acute otitis media was defined as AOM lasting longer than 3 weeks despite 1 or several courses of antibiotic therapy, with the persistence of clinical and otoscopic signs of AOM. From 1982 to 1997, 475 children with PAOM were seen in our department. Every patient had 1 or several specimens of aspirations or swabs of spontaneous otorrhea (or both). Microbiologic characteristics of the isolated strains (including antibiotic susceptibility) were analyzed. Four successive series of specimens were analyzed-group 1: from October 1, 1982, to June 30, 1986 (136 patients); group 2: from January 1, 1987, to December 31, 1989 (165 patients); group 3: from January 1, 1992, to April 30, 1993 (73 patients); and group 4: from January 1, 1994, to January 31, 1997 (101 patients). During the same study periods, the bacteriologic results of patients with AOM in the same geographic region were recorded. MAIN OUTCOME MEASURES: A longitudinal comparison between the groups of patients with PAOM and a cross-comparison within each group between patients with PAOM and those with AOM. RESULTS: Obtaining repeated and multiple specimens from patients with PAOM led to a progressive decrease in the rate of sterile specimens, from 35.3% (group 1, 48 patients) to 14.9% (group 4, 15 patients) (P<.01). During this period, the prevalence of Streptococcus pneumoniae increased in patients with positive culture results, from 18.2% (group 1, 16 of 88 patients) to 44.2% (group 4, 38 of 86 patients) (P<.001). These strains rapidly and dramatically became resistant to penicillin (amoxicillin) (0% through 1989, 76.2% [16 of 21 patients] in 1993, and 97.4% [37 of 38 patients] in 1996) (P = .01). The overall prevalence of Haemophilus influenzae remained stable (between 31.4% [27 of 86 patients] and 45.4% [40 of 88 patients]), but the proportion of beta-lactamase-producing strains increased from 30.0% (group 1, 12 patients) to 55.6% (group 4, 15 patients) (P=.04). The prevalences of Pseudomonas aeruginosa and Staphylococcus aureus did not vary significantly (from 23.1% [group 2, 30 patients] to 10.7% [group 3, 6 patients] and from 10.2% [group 1, 9 patients] to 4.6% [group 4, 4 patients], respectively). Comparing data from patients with PAOM with those with AOM revealed that the increased resistance of H influenzae and, in particular, of S pneumoniae was more rapid and more marked in patients with PAOM than in those with AOM (highest rate of resistance in AOM: 36.0% [271 of 753 specimens] and 50.6% [398 of 787 specimens] for H influenzae and S pneumoniae, respectively; P<.001 for S pneumoniae). CONCLUSIONS: The increase in bacterial resistance frequently encountered during otitis media is even more marked in patients with PAOM. The identification of the organism is essential when the otitis does not resolve, especially in patients with PAOM. Obtaining repeated specimens helps to decrease the rate of sterile cultures.

[Klebsiella oxytoca septicemia following platelet transfusion]. / Septicémies a Klebsiella oxytoca après transfusions de plaquettes.

Two fractions of a three-day-old apheresis platelet collection from a known habitual donor were transfused to two children with thrombocytopenia and bleeding. Both patients developed evidence of severe infection during the transfusion. One died despite intensive care and antimicrobial therapy. The other, whose transfusion was cut short, recovered. A Klebsiella oxytoca strain was recovered from the two transfusion bags, from a third unused bag, and from blood samples from the patient who died. Genotyping results established that all these isolates were identical. Tests for K. oxytoca were negative on the batches of blood donation material, the bottle of antiseptic used, and throat and stool specimens from the donor and phlebotomists. The most likely hypothesis is that the donor developed transient asymptomatic bacteremia during the 136-minute-long collection procedure and that the organism subsequently grew in the platelet collections, which were kept at 20-24 degrees C with agitation for three days before being used.

CDC group IV c-2: a new Ralstonia species close to Ralstonia eutropha.

CDC group IV c-2, an environmental gram-negative bacillus recently proposed for inclusion in the genus Ralstonia, has been isolated in several human infections. Biochemical characterization and 16S ribosomal DNA (rDNA) sequencing with phylogenetic analysis were used to characterize eight clinical isolates and four type strains. Other typing tools, such as pulsed-field gel electrophoresis (PFGE) and randomly amplified polymorphic DNA (RAPD) analysis, were also used. PFGE typing of clinical isolates was unsuccessful because the DNA was degraded, and RAPD analysis was poorly discriminatory. In contrast, the type strains were clearly distinguished with both PFGE and RAPD analysis. All of the 16S rDNA sequences were identical. Comparison of the 16S rDNA sequences to the GenBank sequences showed that they were consistent with CDC group IV c-2 belonging to the genus Ralstonia. The closest matches were obtained with Ralstonia eutropha. However, four differences in 32 biochemical tests separated R. eutropha from CDC group IV c-2, which suggests that CDC group IV c-2 is a new species of the genus Ralstonia.

Comparison of randomly amplified polymorphic DNA analysis and pulsed-field gel electrophoresis for typing of Moraxella catarrhalis strains.

Randomly amplified polymorphic DNA (RAPD) and pulsed-field gel electrophoresis (PFGE) for the analysis of 13 Moraxella catarrhalis isolates, 11 successive strains isolated from sputa of five children and 2 isolates obtained the same day from twins, were compared. RAPD and PFGE both yielded nine types from the 13 isolates, showing a chronic colonization with one strain in three patients and a successive colonization with different strains in two patients. The promising results obtained with RAPD should be confirmed with a larger number of strains, but RAPD seems as suitable as PFGE for the typing of M. catarrhalis.

Investigation of an outbreak of wound infections due to Alcaligenes xylosoxidans transmitted by chlorhexidine in a burns unit.

Alcaligenes xylosoxidans, an environmental gram-negative bacillus, was isolated within a 1-month period from six patients in a pediatric burns unit. Twelve isolates were studied, one from each of the six patients (five from wound cultures and one from a blood culture) and one from each of six contaminated atomizers containing chlorhexidine diluted to 600 mg/l. The biochemical and susceptibility patterns of all the isolates were similar, and their DNA enzyme restriction patterns were identical. The epidemic strain of Alcaligenes xylosoxidans was probably introduced into the atomizers during handling of the diluted solution, which failed to eliminate it.