Development of a Real-Time PCR for Identification of Brachyspira Species in Human Colonic Biopsies

Background: Brachyspira species are fastidious anaerobic microorganisms, that infect the colon of various animals. The genus contains both important pathogens of livestock as well as commensals. Two species are known to infect humans: B. aalborgi and B. pilosicoli. There is some evidence suggesting that the veterinary pathogenic B. pilosicoli is a potential zoonotic agent, however, since diagnosis in humans is based on histopathology of colon biopsies, species identification is not routinely performed in human materials. Methods: The study population comprised 57 patients with microscopic evidence of Brachyspira infection and 26 patients with no histopathological evidence of Brachyspira infection. Concomitant faecal samples were available from three infected patients. Based on publically available 16S rDNA gene sequences of all Brachyspira species, species-specific primer sets were designed. DNA was extracted and tested by real-time PCR and 16S rDNA was sequenced. Results: Sensitivity and specificity for identification of Brachyspira species in colon biopsies was 100% and 87.7% respectively. Sequencing revealed B. pilosicoli in 15.4% of patients, B. aalborgi in 76.9% and a third species, tentatively named ‘‘Brachyspira hominis’’, in 26.2%. Ten patients (12.3%) had a double and two (3.1%) a triple infection. The presence of Brachyspira pilosicoli was significantly associated with inflammatory changes in the colon-biopsy (p = 0.028). Conclusions: This newly designed PCR allows for sub-differentiation of Brachyspira species in patient material and thus allows large-scaled surveillance studies to elucidate the pathogenicity of human Brachyspira infections. One-third of affected patients appeared to be infected with a novel species

Global, regional, and national burden of disorders affecting the nervous system, 1990–2021: a systematic analysis for the Global Burden of Disease Study 2021

Background Disorders affecting the nervous system are diverse and include neurodevelopmental disorders, late-life neurodegeneration, and newly emergent conditions, such as cognitive impairment following COVID-19. Previous publications from the Global Burden of Disease, Injuries, and Risk Factor Study estimated the burden of 15 neurological conditions in 2015 and 2016, but these analyses did not include neurodevelopmental disorders, as defined by the International Classification of Diseases (ICD)-11, or a subset of cases of congenital, neonatal, and infectious conditions that cause neurological damage. Here, we estimate nervous system health loss caused by 37 unique conditions and their associated risk factors globally, regionally, and nationally from 1990 to 2021. Methods We estimated mortality, prevalence, years lived with disability (YLDs), years of life lost (YLLs), and disability-adjusted life-years (DALYs), with corresponding 95% uncertainty intervals (UIs), by age and sex in 204 countries and territories, from 1990 to 2021. We included morbidity and deaths due to neurological conditions, for which health loss is directly due to damage to the CNS or peripheral nervous system. We also isolated neurological health loss from conditions for which nervous system morbidity is a consequence, but not the primary feature, including a subset of congenital conditions (ie, chromosomal anomalies and congenital birth defects), neonatal conditions (ie, jaundice, preterm birth, and sepsis), infectious diseases (ie, COVID-19, cystic echinococcosis, malaria, syphilis, and Zika virus disease), and diabetic neuropathy. By conducting a sequela-level analysis of the health outcomes for these conditions, only cases where nervous system damage occurred were included, and YLDs were recalculated to isolate the non-fatal burden directly attributable to nervous system health loss. A comorbidity correction was used to calculate total prevalence of all conditions that affect the nervous system combined. Findings Globally, the 37 conditions affecting the nervous system were collectively ranked as the leading group cause of DALYs in 2021 (443 million, 95% UI 378–521), affecting 3·40 billion (3·20–3·62) individuals (43·1%, 40·5–45·9 of the global population); global DALY counts attributed to these conditions increased by 18·2% (8·7–26·7) between 1990 and 2021. Age-standardised rates of deaths per 100 000 people attributed to these conditions decreased from 1990 to 2021 by 33·6% (27·6–38·8), and age-standardised rates of DALYs attributed to these conditions decreased by 27·0% (21·5–32·4). Age-standardised prevalence was almost stable, with a change of 1·5% (0·7–2·4). The ten conditions with the highest age-standardised DALYs in 2021 were stroke, neonatal encephalopathy, migraine, Alzheimer's disease and other dementias, diabetic neuropathy, meningitis, epilepsy, neurological complications due to preterm birth, autism spectrum disorder, and nervous system cancer. Interpretation As the leading cause of overall disease burden in the world, with increasing global DALY counts, effective prevention, treatment, and rehabilitation strategies for disorders affecting the nervous system are needed. Funding Bill & Melinda Gates Foundation

Global, regional, and national burden of disorders affecting the nervous system, 1990–2021: a systematic analysis for the Global Burden of Disease Study 2021

BackgroundDisorders affecting the nervous system are diverse and include neurodevelopmental disorders, late-life neurodegeneration, and newly emergent conditions, such as cognitive impairment following COVID-19. Previous publications from the Global Burden of Disease, Injuries, and Risk Factor Study estimated the burden of 15 neurological conditions in 2015 and 2016, but these analyses did not include neurodevelopmental disorders, as defined by the International Classification of Diseases (ICD)-11, or a subset of cases of congenital, neonatal, and infectious conditions that cause neurological damage. Here, we estimate nervous system health loss caused by 37 unique conditions and their associated risk factors globally, regionally, and nationally from 1990 to 2021.MethodsWe estimated mortality, prevalence, years lived with disability (YLDs), years of life lost (YLLs), and disability-adjusted life-years (DALYs), with corresponding 95% uncertainty intervals (UIs), by age and sex in 204 countries and territories, from 1990 to 2021. We included morbidity and deaths due to neurological conditions, for which health loss is directly due to damage to the CNS or peripheral nervous system. We also isolated neurological health loss from conditions for which nervous system morbidity is a consequence, but not the primary feature, including a subset of congenital conditions (ie, chromosomal anomalies and congenital birth defects), neonatal conditions (ie, jaundice, preterm birth, and sepsis), infectious diseases (ie, COVID-19, cystic echinococcosis, malaria, syphilis, and Zika virus disease), and diabetic neuropathy. By conducting a sequela-level analysis of the health outcomes for these conditions, only cases where nervous system damage occurred were included, and YLDs were recalculated to isolate the non-fatal burden directly attributable to nervous system health loss. A comorbidity correction was used to calculate total prevalence of all conditions that affect the nervous system combined.FindingsGlobally, the 37 conditions affecting the nervous system were collectively ranked as the leading group cause of DALYs in 2021 (443 million, 95% UI 378–521), affecting 3·40 billion (3·20–3·62) individuals (43·1%, 40·5–45·9 of the global population); global DALY counts attributed to these conditions increased by 18·2% (8·7–26·7) between 1990 and 2021. Age-standardised rates of deaths per 100 000 people attributed to these conditions decreased from 1990 to 2021 by 33·6% (27·6–38·8), and age-standardised rates of DALYs attributed to these conditions decreased by 27·0% (21·5–32·4). Age-standardised prevalence was almost stable, with a change of 1·5% (0·7–2·4). The ten conditions with the highest age-standardised DALYs in 2021 were stroke, neonatal encephalopathy, migraine, Alzheimer's disease and other dementias, diabetic neuropathy, meningitis, epilepsy, neurological complications due to preterm birth, autism spectrum disorder, and nervous system cancer.InterpretationAs the leading cause of overall disease burden in the world, with increasing global DALY counts, effective prevention, treatment, and rehabilitation strategies for disorders affecting the nervous system are needed

Example of the melting-curve analysis.

<p>There is a clear difference in melting-temperature between the type-strain of <i>B. pilosicoli</i> and <i>B. aalborgi</i>. Biopsy samples containing these species fall neatly within these graphs (patients #13 and #23). <i>“B. hominis”</i> (patient #14) is visible as a peak between the type strains, indicating a different base-pair composition. The double infection (patient #26) begins as a <i>B. pilosicoli</i>-peak with a clear shoulder under the <i>“B. hominis”</i> peak, indicating that two different DNA molecules are present, each with a different melting-temperature-peak. The triple infection (patient #41) is displayed here by the biopsy sample that had both a <i>B. pilosicoli</i> and a <i>B. aalborgi</i>, another biopsy sample taken from this patient at the same time indicated an infection with <i>“B. hominis”</i> (data not shown).</p

Comparison of melting-curve prediction to sequence result^*.

*<p>Multi-infections are not shown in this table, since all multi-infections were predicted correctly.</p

Schematic representation of the relative position of the Brachyspira primers and resultant PCR fragments.

<p>Numbering and fragment sizes according to the 16S sequence of the type strain of <i>B. aalborgi</i> (NCTC 11492). Fragment names refer to <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0052281#pone-0052281-t001" target="_blank">Table 1</a>.</p

Primer sets, length of amplicon, annealing temperature, extension time and PCR-protocol.

<p> <b>PCR conditions</b></p><p>Primer concentration: 2,5 µM of both forward and reverse primers.</p><p>Buffer composition: LightCycler® 480 SYBR Green I Master.</p><p> <b>PCR volume</b></p><p>15 µl buffer and 5 µl DNA-eluate per PCR.</p><p> <b>PCR consumables</b></p><p>White 96-well plate (Roche Diagnostics, Almere, The Netherlands) sealed with transparent self-adhesive foil (Roche Diagnostics, Almere, The Netherlands).</p><p> <b>PCR protocol</b></p><p>Pre-incubation at 95°C for 10 minutes, de-annealing at 95°C for 10 seconds, 10 seconds annealing at the above-specified temperature, amplification at 72°C for the above specified time, 45 cycles. Melting-curve analysis: 5 seconds at 95°C, one minute at 65°C, 2.2°C per second increase of temperature until 97°C with five acquisitions per degree Celsius.</p

Statistical Analyses of Clinical Data^#.

#<p>There were 8 patients with double infections (B. pilosicoli+“B. hominis” n = 1; B. aalborgi+“B. hominis” n = 7) and 2 with triple infection. These were analysed in all groups.</p><p>Chi-squared test was used in all analyses.</p><p>Faecal samples were omitted from analyses.</p>*<p>Inflammatory changes is calculated for all biopsy samples (<i>B. pilosicoli</i> n = 7; <i>B. aalborg</i>i n = 45 and “<i>B. hominis</i>” n = 15), since this could be established for all biopsy samples.</p