Biomedical subjects

Colin Tinsley

Publications and source records attributed to Colin Tinsley.

3 recordsLinked to original sources

PubMed2003

Molecular analysis and experimental virulence of French and North American Escherichia coli neonatal meningitis isolates: identification of a new virulent clone.

Phylogenetic relationships, virulence factors, alone and in specific combinations, and virulence in a rat meningitis model were examined among 132 isolates of Escherichia coli neonatal meningitis from France and North America. Isolates belonging to phylogenetic groups A (n=11), D (n=20), and B2 (n=99) had similar high prevalence rates of the siderophores aerobactin and yersiniabactin and the K1 capsule (>/=70%) yet induced different level of experimental bacteremia. Ectochromosomal DNA-like domains involved in blood-brain barrier passage (PAI III(536) [sfa/foc and iroN; 34%]; GimA [ibeA and ptnC; 38%]; PAI II(J96) [hly, cnf1, and hra; 10%]) were restricted to B2 isolates. Among group B2 isolates, representatives of the O45:K1 clonal group (n=30), which lacked these domains, were as able as the archetypal O18:K1 strain C5 to cause meningitis. Molecular epidemiology combined with experimental virulence assays demonstrate that known virulence factors are insufficient to fully explain the pathophysiology of ECNM and to allow for rational search for new virulence factors.

Animals↗

PubMed2002

Representational difference analysis between Afa/Dr diffusely adhering Escherichia coli and nonpathogenic E. coli K-12.

Diffusely adhering Escherichia coli strains harboring Afa/Dr adhesins (Afa/Dr DAEC) have been associated with diarrhea and urinary tract infections (UTIs). The present work is the first extensive molecular study of a Afa/Dr DAEC strain using the representational difference analysis technique. We have searched for DNA sequences present in strain C1845, recovered from a diarrheagenic child, but absent from a nonpathogenic K-12 strain. Strain C1845 harbors part of a pathogenicity island (PAI(CFT073)) and several iron transport systems found in other E. coli pathovars. We did not find genes encoding factors known to subvert host cell proteins, such as type III secretion system or effector proteins. Several C1845-specific sequences are homologous to putative virulence genes or show no homology with known sequences, and we have analyzed their distribution among Afa/Dr and non-Afa/Dr clinical isolates and among strains from the E. coli Reference Collection. Three C1845-specific sequences (MO30, S109, and S111) have a high prevalence (77 to 80%) among Afa/Dr strains and a low prevalence (12 to 23%) among non-Afa/Dr strains. In addition, our results indicate that strain IH11128, an Afa/Dr DAEC strain recovered from a patient with a UTI, is genetically closely related to strain C1845.

Adhesins, Bacterial↗

PubMed2002

Comparative genomics identifies the genetic islands that distinguish Neisseria meningitidis, the agent of cerebrospinal meningitis, from other Neisseria species.

Neisseria meningitidis colonizes the nasopharynx and, unlike commensal Neisseria species, is capable of entering the bloodstream, crossing the blood-brain barrier, and invading the meninges. The other pathogenic Neisseria species, Neisseria gonorrhoeae, generally causes an infection which is localized to the genitourinary tract. In order to investigate the genetic basis of this difference in disease profiles, we used a strategy of genomic comparison. We used DNA arrays to compare the genome of N. meningitidis with those of N. gonorrhoeae and Neisseria lactamica, a commensal of the nasopharynx. We thus identified sequences conserved among a representative set of virulent strains which are either specific to N. meningitidis or shared with N. gonorrhoeae but absent from N. lactamica. Though these bacteria express dramatically different pathogenicities, these meningococcal sequences were limited and, in contrast to what has been found in other pathogenic bacterial species, they are not organized in large chromosomal islands.

Bacterial Proteins↗