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Nasopharyngeal Carriage (nasopharyngeal + carriage)

Distribution by Scientific Domains

Medical Sciences	60%

Selected Abstracts

Serotypes of carriage and invasive isolates of Streptococcus pneumoniae in Brazilian children in the era of pneumococcal vaccines

CLINICAL MICROBIOLOGY AND INFECTION, Issue 1 2006
C. B. Laval
Abstract Nasopharyngeal carriage of Streptococcus pneumoniae is a key factor in the development of invasive disease and the spread of resistant strains within the community. A single nasopharyngeal swab was obtained from 648 unvaccinated children aged <5 years, either healthy or with acute respiratory tract infection or meningitis, during the winters of 2000 and 2001. The overall pneumococcal carriage rate was 35.8% (95% CI 32.1,39.6). The pneumococcal serotypes found most frequently in the nasopharynx were 14, 6B, 6A, 19F, 10A, 23F and 18C, which included five of the seven serotypes in the currently licensed seven-valent conjugate vaccine (PCV7); serotypes 4 and 9V were less common. Serotypes 1 and 5 were isolated rarely from the nasopharynx. A comparison of 222 nasopharyngeal isolates with 125 invasive isolates, matched for age and time to the carrier isolates, showed a similar prevalence of penicillin non-susceptible pneumococci (PNSp) (19.8% and 19.2%, respectively). PNSp serotypes were similar (6B, 14, 19F, 19 A, 23B and 23F) for carriage and invasive disease isolates. The coverage of PCV7 for carriage isolates (52.2%) and invasive isolates (62.4%) did not differ significantly (p 0.06); similarly, there was no significant difference in PCV7 coverage for carriage isolates (34.5%) and invasive isolates (28.2%) of PNSp. These data suggest that PCV7 has the potential to reduce pneumococcal carriage and the number of carriers of PNSp belonging to vaccine serotypes. [source]

Prevention of pneumococcal disease in children.

ACTA PAEDIATRICA, Issue 5 2001
Pneumococcal conjugate vaccines: their use globally could have a major impact on public health
Pneumococcal disease is a major cause of morbidity and mortality in infants and young children worldwide. New pneumococcal conjugate vaccines include 7 to 11 serotypes, which are the most common cause of paediatric disease in most parts of the world. The efficacy of a 7-valent conjugate vaccine was 97.4% (95% CI, 82.7,99.9) against invasive pneumococcal disease, and 57% (95% CI, 44,67) against otitis media, caused by vaccine serotypes. Evidence shows that the vaccine has the potential to prevent pneumonia. Pneumococcal conjugate vaccination has also been shown to reduce nasopharyngeal carriage of vaccine serotypes (particularly serotypes associated with antibiotic resistance). Thus widespread use of pneumococcal conjugate vaccine could substantially reduce the burden of invasive disease and would have the potential to control the global spread of antibiotic resistance in pneumococci. Conclusion: It is important that these highly effective vaccines should be made available to children in the developing countries. [source]

Sucrose metabolism contributes to in vivo fitness of Streptococcus pneumoniae

MOLECULAR MICROBIOLOGY, Issue 1 2007
Ramkumar Iyer
Summary We characterized two sucrose-metabolizing systems ,sus and scr, and describe their roles in the physiology and virulence of Streptococcus pneumoniae in murine models of carriage and pneumonia. The sus and scr systems are regulated by LacI family repressors SusR and ScrR respectively. SusR regulates an adjacent ABC transporter (susT1/susT2/susX) and sucrose-6-phosphate (S-6-P) hydrolase (susH). ScrR controls an adjacent PTS transporter (scrT), fructokinase (scrK) and second S-6-P hydrolase (scrH). sus and scr play niche-specific roles in virulence. The susH and sus locus mutants are attenuated in the lung, but dispensable in nasopharyngeal carriage. Conversely, the scrH and scr locus mutants, while dispensable in the lung, are attenuated for nasopharyngeal colonization. The scrH/susH double mutant is more attenuated than scrH in the nasopharynx, indicating SusH can substitute in this niche. Both systems are sucrose-inducible, with ScrH being the major in vitro hydrolase. The scrH/susH mutant does not grow on sucrose indicating that sus and scr are the only sucrose-metabolizing systems in S. pneumoniae. We propose a model describing hierarchical regulation of the scr and sus systems by the putative inducer, S-6-P. The transport and metabolism of sucrose or a related disaccharide thus contributes to S. pneumoniae colonization and disease. [source]

Large-scale identification of serotype 4 Streptococcus pneumoniae virulence factors

MOLECULAR MICROBIOLOGY, Issue 5 2002
David L. Hava
Summary Streptococcus pneumoniae (the pneumococcus) is carried in the nasopharynx of healthy individuals, but can spread to other host sites and lead to pneumonia, bacteraemia, otitis media and meningitis. Although it is logical to think a priori that differential gene expression would contribute to the ability of this patho-gen to colonize different sites, in fact very few genes have been demonstrated to play tissue specific roles in virulence or carriage. Using signature-tagged mutagenesis to screen 6149 mariner -transposon insertion strains, we identified 387 mutants attenuated for infection in a murine model of pneumonia. Among these mutants are ones with disruptions in a number of putative tissue-specific transcriptional regulators, surface proteins, metabolic proteins and proteins of unknown function, most of which had not previously been associated with virulence. A subset of these, including most of those with insertions in putative transcriptional regulators, was examined for phenotypes in murine models of bacteraemia and nasopharyngeal carriage. Four classes of mutants defective in infection models of the: (I) lung, (II) lung and blood, (III) lung and nasopharynx, and (IV) all three tissues were identified, thus demonstrating the ex-istence of tissue-specific pneumococcal virulence factors. Included in these strains were two with disruptions in a genetic locus that putatively codes for a transcriptional regulator, three surface proteins and three sortase homologues. Mutation analysis revealed that three of the seven genes in this locus are virulence factors that are specific to mucosal surfaces. [source]

An outbreak of pneumonia associated with S. pneumoniae at a military training facility in Finland in 2006

APMIS, Issue 7 2009
ANNI VAINIO
Streptococcus pneumoniae is a well-known cause of community-acquired bacterial pneumonia. The purpose of this study was to assess the cause and extent of the outbreak of pneumonia which occurred among military recruits following a 1-week hard encampment in Finland. We also assessed the carriage rate and molecular characteristics of the S. pneumoniae isolates. All pneumococcal isolates were studied for antibiotic susceptibility, serotyped, genotyped by multilocus sequence typing (MLST), and the presence of pneumococcal rlrA pilus islet was detected. The genotype results defined by MLST corresponded with the serotype results. S. pneumoniae serotype 7F, ST2331, seemed to be associated with an outbreak of pneumonia and nasopharyngeal carriage among 43 military recruits. Of the 43 military recruits, five (12%) were hospitalized with pneumonia and two (40%) of them were positive for S. pneumoniae serotype 7F, ST2331 by blood culture. Eighteen (42%) of the 43 men were found to be positive for S. pneumoniae by nasopharyngeal culture, and nine (50%) of them carried pneumococcal serotype 7F, ST2331. The outbreak strain covered 55% of all the pneumococcal findings. Outbreaks of invasive pneumococcal disease seem to occur in a crowded environment such as a military training facility even among previously healthy young men. [source]