Molecular background of novel silent RHCE alleles.

BACKGROUND: The absence of expression of C/c and E/e antigens has been associated with rare variant RHCE alleles, referred to as silent RHCE alleles, classically identified among individuals with a rare D- - or Rhnull phenotype. This work reports on different molecular mechanisms identified in three novel silent RHCE alleles. STUDY DESIGN AND METHODS: Samples from D- - or Rhnull individuals and their family members, from families for whom Rh phenotype and/or serologic data were unexplained by inheritance of conventional RH alleles, were analyzed. Genomic DNA and transcripts were tested by sequencing analysis. RESULTS: The first silent allele was a RHCE*cE allele carrying an intronic IVS3+5G>A mutation. The second was a RHCE*ce allele carrying an intronic IVS7-2A>G mutation, whereas the third was a silent RHCE*ce allele carrying a 5-bp deletion (Nucleotides 679-683) in Exon 5. CONCLUSION: In addition to hybrid alleles and nucleotide deletion, intronic mutations may be associated with the nonexpression of RhCE antigens. Regarding the RH system, silent alleles may not be investigated among D- - or Rhnull individuals only. Rh phenotype and/or serologic data unexplained by inheritance of conventional RH alleles should lead to molecular investigations.

Species distribution and ribotype diversity of Burkholderia cepacia complex isolates from French patients with cystic fibrosis.

A total of 153 Burkholderia cepacia strains obtained from 153 French patients with cystic fibrosis were identified as Burkholderia multivorans (51.6%) or Burkholderia cenocepacia (45.1%). Eighty-two genotypes were identified using PvuII and EcoRI ribotyping. B. multivorans genotype A (found in 32 French patients) and two other genotypes were also identified among isolates from Austrian, German, Italian, and Canadian patients.

Epidemiologic investigation of Burkholderia cepacia acquisition in two pediatric intensive care units.

OBJECTIVES: To investigate and describe an outbreak of Burkholderia cepacia in a neonatal intensive care unit (NICU) and a pediatric intensive care unit (PICU), and to report the interventions leading to the cessation of the outbreak. DESIGN: We conducted an epidemiologic investigation of an outbreak of B. cepacia colonization or infection in two clinical wards during a 35-month period (December 1998 to October 2001). SETTING: A 500-bed, university hospital-affiliated, tertiary-care pediatric institution in Paris, France, with a 22-bed PICU and 31-bed NICU. METHODS: Ribotyping was used to determine the genotypes of B. cepacia isolates. Procedures for the maintenance and disinfection of respiratory therapy devices were reviewed. RESULTS: Thirty-two children were colonized (n = 14) or infected (n = 18) by B. cepacia in 2 wards (28 in the PICU and 4 in the NICU). In the PICU, a single ribotype was found among the isolates obtained from all of the patients except 1, and from the 6 isolates obtained from respiratory therapy devices (ie, heated humidifier water). In the NICU, the isolates obtained from the patients harbored a single ribotype unrelated to that of the epidemic strain isolated in the PICU; no environmental source of infection was found. CONCLUSION: Two different outbreaks appeared to be associated with 2 ribotypes, 1 of which was linked to patient-to-patient transmission via respiratory therapy devices. Complete elimination of the outbreak was achieved only when disposable, sterilizable, or easy-to-disinfect materials were used in the PICU. The source of infection in the NICU was not found.

Activity of telithromycin against penicillin-resistant Streptococcus pneumoniae isolates recovered from French children with invasive and noninvasive infections.

We compared the activities of telithromycin, erythromycin, azithromycin, josamycin, penicillin G, amoxicillin, cefpodoxime, and ceftriaxone against invasive and noninvasive non-penicillin-susceptible Streptococcus pneumoniae isolates recovered from children. Of the 186 isolates tested, 89% were positive for erm(B) by PCR. Telithromycin had the lowest MICs, with MICs at which 90% of the isolates tested are inhibited of 0.032 and 0.25 micro g/ml for erythromycin-sensitive and -resistant isolates, respectively.

Phenotypic and genetic diversity of invasive pneumococcal isolates recovered from French children.

We investigated the phenotypic and genetic diversity (by ribotyping) of Streptococcus pneumoniae isolates recovered from French children, by blood culture from meningitis-free patients (n = 244) and by cerebrospinal fluid culture from patients with meningitis (n = 154). Isolates belonging to serotypes associated with carriage and penicillin-resistant isolates were significantly more frequent in children under 2 years of age than in older children. The seven-valent pneumococcal conjugate vaccine covered 68% of strains associated with bacteremia and 61% of strains associated with meningitis in children under 2 years. Although some serotypes were recovered more frequently from children with bacteremia than from those with meningitis, no difference in the genetic backgrounds of the two groups of strains was found.

Phylogenetic analysis and prevalence of urosepsis strains of Escherichia coli bearing pathogenicity island-like domains.

We characterized 100 Escherichia coli urosepsis isolates from adult patients according to host compromise status by means of ribotyping, PCR phylogenetic grouping, and PCR detection of papG alleles and the virulence-related genes sfa/foc, fyuA, irp-2, aer, hly, cnf-1 and hra. We also tested these strains for copies of pap and hly and their direct physical linkage with other virulence genes in an attempt to look for pathogenicity islands (PAIs) described for the archetypal uropathogenic strains J96, CFT073, and 536. Most of the isolates belonged to E. coli phylogenetic groups B2 and D and bore papG allele II, aer, and fyuA/irp-2. papG allele II-bearing strains were more common in noncompromised patients, while papG allele-negative strains were significantly more frequent in compromised patients. Fifteen ribotypes were identified. The three archetypal strains harbored different ribotypes, and only one-third of our urosepsis strains were genetically related to one of the archetypal strains. Three and 18 strains harbored three and two copies of pap, respectively, and 5 strains harbored two copies of hly. papGIII was physically linked to hly, cnf-1, and hra (reported to be PAI II(J96)-like genetic elements) in 14% of the strains. The PAI II(J96)-like domain was inserted within pheR tRNA in 11 strains and near leuX tRNA in 3 strains. Moreover, the colocalized genes cnf-1, hra, and hly were physically linked to papGII in four strains and to no pap gene in three strains. papGII and hly (reported to be PAI I(CFT073)-like genetic elements) were physically linked in 16 strains, pointing to a PAI I(CFT073)-like domain. Three strains contained both a PAI II(J96)-like domain and a PAI I(CFTO73)-like domain. Forty-two strains harbored papGII but not hly, in keeping with the presence of a PAI II(CFT073)-like domain. Only one strain harbored a PAI I(536)-like domain (hly only), and none harbored a PAI I(J96)-like domain (papGI plus hly) or a PAI II(536)-like domain (papGIII plus hly). This study provides new data on the prevalence and variability of physical genetic linkage between pap and certain virulence-associated genes that are consistent with their colocalization on archetypal PAIs.