Comparison of routine field epidemiology and whole genome sequencing to identify tuberculosis transmission in a remote setting

Yukon Territory (YT) is a remote region in northern Canada with ongoing spread of tuberculosis (TB). To explore the utility of whole genome sequencing (WGS) for TB surveillance and monitoring in a setting with detailed contact tracing and interview data, we used a mixed-methods approach. Our analysis included all culture-confirmed cases in YT (2005-2014) and incorporated data from 24-locus Mycobacterial Interspersed Repetitive Units-Variable Number of Tandem Repeats (MIRU-VNTR) genotyping, WGS and contact tracing. We compared field-based (contact investigation (CI) data + MIRU-VNTR) and genomic-based (WGS + MIRU-VNTR + basic case data) investigations to identify the most likely source of each person's TB and assessed the knowledge, attitudes and practices of programme personnel around genotyping and genomics using online, multiple-choice surveys (n = 4) and an in-person group interview (n = 5). Field- and genomics-based approaches agreed for 26 of 32 (81%) cases on likely location of TB acquisition. There was less agreement in the identification of specific source cases (13/22 or 59% of cases). Single-locus MIRU-VNTR variants and limited genetic diversity complicated the analysis. Qualitative data indicated that participants viewed genomic epidemiology as a useful tool to streamline investigations, particularly in differentiating latent TB reactivation from the recent transmission. Based on this, genomic data could be used to enhance CIs, focus resources, target interventions and aid in TB programme evaluation.

Whole genome sequencing for improved understanding of Mycobacterium tuberculosis transmission in a remote circumpolar region

Few studies have used genomic epidemiology to understand tuberculosis (TB) transmission in rural and remote settings - regions often unique in history, geography and demographics. To improve our understanding of TB transmission dynamics in Yukon Territory (YT), a circumpolar Canadian territory, we conducted a retrospective analysis in which we combined epidemiological data collected through routine contact investigations with clinical and laboratory results. Mycobacterium tuberculosis isolates from all culture-confirmed TB cases in YT (2005-2014) were genotyped using 24-locus Mycobacterial Interspersed Repetitive Units-Variable Number of Tandem Repeats (MIRU-VNTR) and compared to each other and to those from the neighbouring province of British Columbia (BC). Whole genome sequencing (WGS) of genotypically clustered isolates revealed three sustained transmission networks within YT, two of which also involved BC isolates. While each network had distinct characteristics, all had at least one individual acting as the probable source of three or more culture-positive cases. Overall, WGS revealed that TB transmission dynamics in YT are distinct from patterns of spread in other, more remote Northern Canadian regions, and that the combination of WGS and epidemiological data can provide actionable information to local public health teams.

Neonatal Torulopsis glabrata fungemia

Torulopsis glabrata is a yeastlike fungus that has recently become recognized as an important opportunistic pathogen. Only four cases of T glabrata infection in neonates have been reported. We report two cases of fungemia caused by this organism in premature infants. Both patients were treated with amphotericin B and survived the fungemia, but one patient later died of bacterial sepsis. Both patients had been treated with surfactant, artificial ventilation, intravascular catheters (arterial and venous), broad spectrum antibiotics, and hyperalimentation, which appear to be risk factors for T glabrata fungemia. A review of the literature indicates that T glabrata is susceptible to amphotericin B and 5-fluorocytosine and is resistant to fluconazole. In addition, it is less susceptible to ketoconazole, clotrimazole, and itraconazole than is Candida albicans. We recommend that T glabrata infections be treated initially by reducing iatrogenic risk factors and beginning amphotericin B therapy. If necessary, 5-fluorocytosine should be added to the drug regimen.

The effects of selenium on the distribution of mercury in the organs of the black bullhead (Ictalurus melas)

Following i.p. mercuric chloride injections, the mercury was deposited primarily in the kidneys. Simultaneous selenium injections prevented mercury induced osmoregulatory failure even though selenium strongly promoted the movement of mercury to the kidneys and its deposition in an approximate 1:1 mercuric selenite ratio. Whole-body retention of mercury was not altered by simultaneous subcutaneous injections of sodium selenite.

Axonal underdevelopment from axotomy in kittens

Permanent axotomy, by hind limb amputation in kittens, is found by morphometric evaluation at 9 months after amputation to result in failure of ventral and dorsal root myelinated fibers (MFs) to attain adult calibers. The positions of the median diameter and of diameter peaks were unequivocally displaced to smaller diameters, but more so for dorsal than for ventral roots. When fiber spectra of amputated roots were compared with those of kittens at the time of amputation, the median diameter, the position of peaks of diameter histograms, and the diameters of largest MFs were clearly at larger diameters, an indication that axonal development had continued (especially for motor fibers) for some time after amputation. These studies have shown that whereas in adult cats, permanent axotomy results in axonal atrophy, in kittens axonal development continues, but stops short of reaching adult values. As axonal caliber presumably ultimately relates to perikaryal synthesis of protein, one must infer either that the signal to decrease protein synthesis is slow in arriving at the perikarya or that the decreased axonal flow of materials resulting from such a signal is slow and thus allows continued axonal growth for a period after amputation.

Epidemiology of gonorrhoea and syphilis in South Australia (1966--77)

Data from the annual general report of the Venereal Disease Control Centre (VDCC) in a state with a population of approximately 1 250 000 people (in 1977), of whom about 1 100 000 live within 25 miles of the centre of Adelaide, the capital city, are presented.