[Role of pneumococcus in pediatric infectious pathology]

Online monitoring system for qualitative and quantitative analysis of bioaerosols by combined ATP bioluminescence assay with loop-mediated isothermal amplification

Rapid detection of airborne pathogens is crucial in preventing respiratory infections and allergies. However, technologies aiming to real-time analysis of microorganisms in air remain limited due to the sparse and complex nature of bioaerosols. Here, we introduced an online bioaerosol monitoring system (OBMS) comprised of integrated units including a rotatable stainless-steel sintered filter-based sampler, a lysis unit for extracting adenosine triphosphate (ATP), and a single photon detector-based fluorescence unit. Through optimization of the ATP bioluminescence method and establishment of standard curves between relative luminescence units (RLUs) and ATP as well as microbial concentration, we achieved simultaneous detection of bioaerosols' concentration and activity. Testing OBMS with four bacterial and two fungal aerosols at a sampling flow rate of 10 to 50 L/min revealed an outstanding collection efficiency of 95 % at 30 L/min. A single OBMS measurement takes only 8 min (sampling: 5 min; lysis and detection: 3 min) with detection limits of 3 Pcs/ms photons (2.9 × 103 and 292 CFU/m3 for Staphylococcus aureus and Candida albicans aerosol). In both laboratory and field tests, OBMS detected higher concentrations of bioaerosol compared to the traditional Andersen impactor and liquid biosampler. When combined OBMS with loop-mediated isothermal amplification (LAMP), the bioaerosol can be qualitative and quantitative analyzed within 40 min without the cumbersome procedures of sample pretreatment and DNA extraction. These results offer a high compressive and humidity resistance membrane filtration sampler and validate the potential of OBMS for online measurement of bioaerosol concentration and composition.

Serotype distribution and antimicrobial resistance of invasive and noninvasive pneumococcal isolates in Tunisia

Pneumococcal conjugate vaccines have not yet been introduced into the national program for childhood vaccination in Tunisia. The aim of this 7-year study was to obtain local data about serotype distribution and antimicrobial resistance of Streptococcus pneumoniae. A total of 203 isolates of culture confirmed that S. pneumoniae was evaluated. Invasive (n=108) and noninvasive (n=95) pneumococcal isolates were obtained from patients aged from 1 month to 85 years old. Considering all age groups, vaccine coverage was 40%, 62%, and 68% for PCV7, PCV10, and PCV13 serotypes, respectively. Overall, 31% of these isolates were penicillin G nonsusceptible. The most prevalent serotypes identified were those found in currently available pneumococcal conjugate vaccines, emphasizing the importance of implementing the vaccine in the routine immunization schedule at the national level.

Late and ultra late onset Streptococcus B meningitis: clinical and bacteriological data over 6 years in France

BACKGROUND

Group B Streptococcus (GBS) is one of the leading causes of sepsis and meningitis in newborn. The objective of this study was to describe the characteristics of GBS meningitis in children aged between 7 and 89 days (late onset disease - LOD group) and to compare them with children aged more than 3 months (ultra late onset disease - ULOD group).

METHODS

Clinical and biological data were gathered by ACTIV/GPIP (a nationwide active surveillance network). The study population included 242 children hospitalized between 2001 and 2006 for GBS meningitis (220 in the LOD group and 22 in the ULOD group).

RESULTS

Univariate analysis revealed that gestational age (GA) was significantly lower in the ULOD group as compared with the LOD group (respectively 35.6 weeks vs. 37.9 weeks, p = 0.002). Prevalence of early preterm birth (before the 32nd week GA) was significantly higher in the ULOD group than in the LOD group (32% vs. 7%, p = 0.002). No significant difference was found between the two groups for biological characteristics of lumbar puncture, GBS serotypes, complications and survival rate.

CONCLUSION

These data suggest that LOD and ULOD would be the same clinical and bacteriological entity, except for prematurity, which seems significantly associated with ULOD.

[Streptococcus pneumoniae meningitis in Amiens Hospital between 1990 and 2005. Bacteriological characteristics of strains isolated]

Streptococcus pneumoniae is actually the first most likely organism to cause meningitis in children 2 months to 2 years old and in adults older than 65 years. From January 1990 to December 2005, 72 cases of S. pneumoniae-positive cerebrospinal fluid culture were indexed in our hospital. Among the 72 cases, 25 came from children, and 60% of these came from children under two years of age and 47 came from adults whose the mean age was 55 years. The first penicillin-resistant S. pneumoniae (PNSP) meningitis was identified in 1993. The susceptibility to penicillin of pneumococcal isolates causing meningitis varied according to time; until 1995, 25% of the strains were PNSP, then from 1996 to 2005, 50% of strains were PNSP. The overall prevalence of non-susceptible was 34.7% (25/72). Among the 25 PNSP, 21 were intermediate to penicillin G and four of them were resistant. Among children, seven PNSP meningitis were indexed and one of them was resistant. The antimicrobial MICs of amoxicillin and cefotaxim varied from 0.064 to 1 mg/l and from 0.016 to 0.5 mg/l respectively. Among adults, 18 PNSP meningitis were indexed. Three strains were penicillin-resistant. The antimicrobial MICs of amoxicillin varied from 0.064 to 2 mg/l. Nine strains of 18 PNSP had cefotaxim MIC>/=0.5 mg/l and, four of them had MIC 1 mg/l. None amoxicillin and cefotaxim-resistant strain was isolated. Serotyping of all strains was performed in the Reference Center. Serotypes 6B, 9V and 19 were the most frequent in child and serotypes 6B, 23F, 19, 9, 4 were the most frequent in adult. So, all serotypes were represented.

Prescriptions actuelles de l'antibiothérapie chez le nourrisson et l'enfant

Antimicrobial chemotherapy prescription should take into account the following items: 1) accurate diagnosis (most often clinical) and definition criteria of infectious diseases; 2) treatment justification; 3) confirmation of a bacterial etiology (now facilitated in some clinical situations by broadly available easy-to-use rapid diagnosis tests); 4 evidence-based antimicrobial choices; 5) modalities of prescriptions guided by official authorities (guidelines from French agency of medicinal products).

Méningites à pneumocoque de l'enfant en France : âge de survenue et facteurs de risques médicaux

Streptococcus pneumoniae (Sp) is an important cause of morbidity and mortality among paediatric infectious diseases. The aim of this study is to analyse specific data on Sp meningitis out of the Bacterial Meningitis (BM) French Surveillance Network about mean age of BM cases and clinical features. Overall 367 Sp BM were reported between January 2001 to January 2004 (sex ratio M/F: 1.3), 69.7% were < 2 years old, median age 0.8 year (minmax 0-16.8 years). Before two years old children, 94.1% had no medical risk factor and no underlying conditions: on the other hand, after two years old, these factors were reported in 27% cases (P < 0.001). Mortality rate was 10.9%. On account of a Sp BM's pic at five months, data of the BM French Surveillance Network confirm the necessity of an early vaccination. The vaccine administration at two, three, four months with a booster during the second year, recommended in the vaccinal french calendar, seems particularly adapted to the Sp BM in France.

Tolérance et immunogénicité d’un vaccin pneumococcique osidique conjugué heptavalent (Prevenar®) administré en association avec une combinaison vaccinale pédiatrique (DTCoq-Polio/Hib) à des nourrissons selon le schéma vaccinal français à l’âge de deux, trois et quatre mois

Invasive pneumococcal disease is presently a leading cause of mortality due to bacterial infectious diseases in French children less than 2 years of age, and only the pneumococcal conjugate vaccines induce a protective immune response for those within this vulnerable age group.

MATERIAL AND METHODS

The safety and immunogenicity of a heptavalent pneumococcal polysaccharide conjugate vaccine (PREVENAR was tested in French infants immunized with the 2, 3 and 4 month French schedule as part of an open, randomized, comparative clinical study, in association with a whole-cell pertussis-based pediatric combination vaccine.

RESULTS

In the PREVENAR plus DTP-IPV/Hib association group, 90.6-100% of children achieved a post-dose three threshold IgG concentration of >0.15 microg/ml against each of the seven pneumococcal serotypes. Regarding immunogenicity, no interference with the antibody response to the various antigenic components of the DTP-IPV/Hib vaccine was observed. Local reactions were significantly less frequent at the PREVENAR injection site than at the DTP-IPV/Hib injection site; there was no increase in systemic adverse events in the vaccine association group compared to the DTP-IPV/Hib alone group, further exception of fever >38 degrees C which was more frequently reported in the PREVENAR + PENTACOQ group following the second dose of vaccines (56% vs. 35%); no serious adverse event could be considered to be related to the PREVENAR immunization in this study.

CONCLUSION

The heptavalent pneumococcal conjugate vaccine is immunogenic when administered at 2, 3 and 4 months. PREVENAR can be administered simultaneously with the DTP-IPV/Hib combination vaccine.