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Pulmonary infection induced by drugs
Published in Philippe Camus, Edward C Rosenow, Drug-induced and Iatrogenic Respiratory Disease, 2010
Marc B Feinstein, Dorothy A White
For patients receiving these drugs, who are particularly susceptible to encapsulated bacteria, vaccination can be effective in decreasing the incidence of Haemophilus influenzae type b, as well as pneumococcal and meningococcal infections. Vaccines must be administered prior to treatment. As patients, even under optimal conditions, may not manifest an adequate response, the vaccination of household contacts may also be helpful in limiting exposure. The majority of opportunistic infections occur among patients taking glucocorticoids, so it is prudent to avoid treatment concurrently with systemic steroids if possible. A low threshold to antibiotic treatment (i.e. amoxicillin–clavulanate) should exist when patients manifest signs and symptoms of respiratory infections. Finally, prophylaxis with TMP–SMX and acyclovir should be considered among patients who have advanced disease, previous cytotoxic therapy, or CD4 counts below 200 cells/μ L.
Next-generation DNA sequencing of oral microbes at the Sir John Walsh Research Institute: technologies, tools and achievements
Published in Journal of the Royal Society of New Zealand, 2020
Nicholas C. K. Heng, Jo-Ann L. Stanton
Ever since Avery et al. (1944) provided experimental evidence supporting DNA as the ‘transforming principle’ (i.e. genetic material) of cells and the subsequent elucidation of the molecular structure of DNA by Watson and Crick (1953), there has been much research conducted into finding more effective, cost-efficient, and accurate ways to determine the nucleotide sequence of any DNA molecule. It was not until 1977 that two competing sequencing methods were introduced: (i) the dideoxynucleotide chain-termination method of Sanger et al. (1977), and (ii) the chemical modification/cleavage method of Maxam and Gilbert (1977). The ‘Sanger’ sequencing method, which utilised radioactively-labelled synthesis-terminating dideoxynucleotides in combination with DNA polymerase and X-ray films, prevailed as it was more efficient and used less radioactivity. Over the next two decades, Sanger sequencing underwent several key advances including (a) the replacement of radioactive labels with fluorescent dyes, (b) the development of highly-sophisticated fluorescence detection instruments, and (c) the use of thermostable DNA polymerases to facilitate longer sequence read lengths. Current Sanger-based sequencing instruments such as the Applied Biosystems 3730xl Genetic Analyzer can process up to 384 sequencing reactions in a single run, each yielding >900 basepairs (bp) of reliable sequence data (Liu et al. 2012). Despite the long read lengths, Sanger-based sequencing is labour-intensive and relatively expensive (NZ$9.50 per sequence) and is thus largely limited to confirmatory sequencing, e.g. of cloned DNA fragments in recombinant plasmids. Nevertheless, the first bacterial genome to be sequenced completely, that of Haemophilus influenzae, was achieved purely with Sanger-based sequencing (Fleischmann et al. 1995). Even more than 40 years since its invention, Sanger sequencing remains the ‘gold standard’ for nucleotide sequencing with unsurpassed accuracy (Liu et al. 2012). However, significant advancements in miniaturisation technology meant that it was only a matter of time before cost-effective high-throughput DNA sequencing systems would become a reality.