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Biomedical subjects

M B Prentice

Publications and source records attributed to M B Prentice.

14 recordsLinked to original sources
PubMed2001

Genome sequence of Yersinia pestis, the causative agent of plague.

The Gram-negative bacterium Yersinia pestis is the causative agent of the systemic invasive infectious disease classically referred to as plague, and has been responsible for three human pandemics: the Justinian plague (sixth to eighth centuries), the Black Death (fourteenth to nineteenth centuries) and modern plague (nineteenth century to the present day). The recent identification of strains resistant to multiple drugs and the potential use of Y. pestis as an agent of biological warfare mean that plague still poses a threat to human health. Here we report the complete genome sequence of Y. pestis strain CO92, consisting of a 4.65-megabase (Mb) chromosome and three plasmids of 96.2 kilobases (kb), 70.3 kb and 9.6 kb. The genome is unusually rich in insertion sequences and displays anomalies in GC base-composition bias, indicating frequent intragenomic recombination. Many genes seem to have been acquired from other bacteria and viruses (including adhesins, secretion systems and insecticidal toxins). The genome contains around 150 pseudogenes, many of which are remnants of a redundant enteropathogenic lifestyle. The evidence of ongoing genome fluidity, expansion and decay suggests Y. pestis is a pathogen that has undergone large-scale genetic flux and provides a unique insight into the ways in which new and highly virulent pathogens evolve.

Animals↗
PubMed2001

Yersinia pestis pFra shows biovar-specific differences and recent common ancestry with a Salmonella enterica serovar Typhi plasmid.

Population genetic studies suggest that Yersinia pestis, the cause of plague, is a clonal pathogen that has recently emerged from Yersinia pseudotuberculosis. Plasmid acquisition is likely to have been a key element in this evolutionary leap from an enteric to a flea-transmitted systemic pathogen. However, the origin of Y. pestis-specific plasmids remains obscure. We demonstrate specific plasmid rearrangements in different Y. pestis strains which distinguish Y. pestis bv. Orientalis strains from other biovars. We also present evidence for plasmid-associated DNA exchange between Y. pestis and the exclusively human pathogen Salmonella enterica serovar Typhi.

Animals↗
PubMed1993

Comparison of Signal and Bactec NR-660 blood culture systems.

The Signal blood culture system was compared with the Bactec NR-660. A total of 1617 blood culture sets yielded 143 (8.8%) significant isolates; 113 (79.0%) were from positive bottles in both the Bactec and Signal systems. Twelve organisms (8.4%) were detected and isolated from the Signal system only and another 18 (12.6%) from the Bactec system only. Of these 18, five were Signal-positive but the organism was not recovered and four organisms were isolated from negative Signal bottles on terminal subculture. The time taken to detection for each system was similar; the Signal system detected 68% and the Bactec 63% of significant positives within 24 h. At 48 h Bactec detected 91% and the Signal 85%. A significantly-reduced number of bottles which gave a positive signal but were negative by microscopical and cultural methods was found, compared with previous reports. The 1 h incubation period prior to the insertion of the Signal growth indicator device was considered to be the cause of this reduction in the proportion of false positives. Fifty-five percent (42/77) of the Bactec false positives were due to delta growth value. This is when there is an increase in the growth index of > or = 15 without the positive threshold level of 30 being attained. This occurred in the anaerobic bottle on day 2 with 42 bottles. Another 40% (31/77) of the false positives had a growth value between the positive threshold of 30 and a value of 35. Eighty (4.9%) of Bactec and 65 (4.0%) of Signal sets yielded clinically non-significant isolates.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗