Mechanisms behind variation in the Clostridium difficile 16S–23S rRNA intergenic spacer region

Clostridium difficile infection is an increasing problem in hospitals worldwide, mainly due to the recent emergence of a hypervirulent C. difficile strain. C. difficile PCR ribotyping, based on size variation of the 16S–23S rRNA intergenic spacer region (16S–23S ISR), is widely used in Europe for molecular epidemiological investigation. The mechanism underlying the 16S–23S ISR size variations in the genome of C. difficile is currently not completely understood. To elucidate this mechanism, isolates of six different PCR ribotypes were analysed by cloning and sequencing the 16S–23S ISR. A direct repeat, IB, of 9 bp was detected up to five times in the 16S–23S ISR in all 47 clones investigated. Thirty-five clones displayed differences either by ribotype or by nucleotide sequence. The sequences of the 16S–23S ISR of C. difficile showed a uniformly organized structure, composed of a tRNAAla gene and spacers of 33 and 53 bp separated by the 9 bp direct repeat IB. The results of the study support the hypothesis that this composition is responsible for the length variations seen in the 16S–23S ISR, and indicate that these length variations result from slipped-strand mispairing and intra- and possibly interchromosomal homologous recombination

Worldwide trends in underweight and obesity from 1990 to 2022: a pooled analysis of 3663 population-representative studies with 222 million children, adolescents, and adults

Background Underweight and obesity are associated with adverse health outcomes throughout the life course. We estimated the individual and combined prevalence of underweight or thinness and obesity, and their changes, from 1990 to 2022 for adults and school-aged children and adolescents in 200 countries and territories. Methods We used data from 3663 population-based studies with 222 million participants that measured height and weight in representative samples of the general population. We used a Bayesian hierarchical model to estimate trends in the prevalence of different BMI categories, separately for adults (age ≥20 years) and school-aged children and adolescents (age 5–19 years), from 1990 to 2022 for 200 countries and territories. For adults, we report the individual and combined prevalence of underweight (BMI <18·5 kg/m2) and obesity (BMI ≥30 kg/m2). For schoolaged children and adolescents, we report thinness (BMI <2 SD below the median of the WHO growth reference) and obesity (BMI >2 SD above the median). Findings From 1990 to 2022, the combined prevalence of underweight and obesity in adults decreased in 11 countries (6%) for women and 17 (9%) for men with a posterior probability of at least 0·80 that the observed changes were true decreases. The combined prevalence increased in 162 countries (81%) for women and 140 countries (70%) for men with a posterior probability of at least 0·80. In 2022, the combined prevalence of underweight and obesity was highest in island nations in the Caribbean and Polynesia and Micronesia, and countries in the Middle East and north Africa. Obesity prevalence was higher than underweight with posterior probability of at least 0·80 in 177 countries (89%) for women and 145 (73%) for men in 2022, whereas the converse was true in 16 countries (8%) for women, and 39 (20%) for men. From 1990 to 2022, the combined prevalence of thinness and obesity decreased among girls in five countries (3%) and among boys in 15 countries (8%) with a posterior probability of at least 0·80, and increased among girls in 140 countries (70%) and boys in 137 countries (69%) with a posterior probability of at least 0·80. The countries with highest combined prevalence of thinness and obesity in school-aged children and adolescents in 2022 were in Polynesia and Micronesia and the Caribbean for both sexes, and Chile and Qatar for boys. Combined prevalence was also high in some countries in south Asia, such as India and Pakistan, where thinness remained prevalent despite having declined. In 2022, obesity in school-aged children and adolescents was more prevalent than thinness with a posterior probability of at least 0·80 among girls in 133 countries (67%) and boys in 125 countries (63%), whereas the converse was true in 35 countries (18%) and 42 countries (21%), respectively. In almost all countries for both adults and school-aged children and adolescents, the increases in double burden were driven by increases in obesity, and decreases in double burden by declining underweight or thinness. Interpretation The combined burden of underweight and obesity has increased in most countries, driven by an increase in obesity, while underweight and thinness remain prevalent in south Asia and parts of Africa. A healthy nutrition transition that enhances access to nutritious foods is needed to address the remaining burden of underweight while curbing and reversing the increase in obesit

Factors influencing physical activity and rehabilitation in survivors of critical illness: a systematic review of quantitative and qualitative studies

PURPOSE: To identify, evaluate and synthesise studies examining the barriers and enablers for survivors of critical illness to participate in physical activity in the ICU and post-ICU settings from the perspective of patients, caregivers and healthcare providers. METHODS: Systematic review of articles using five electronic databases: MEDLINE, CINAHL, EMBASE, Cochrane Library, Scopus. Quantitative and qualitative studies that were published in English in a peer-reviewed journal and assessed barriers or enablers for survivors of critical illness to perform physical activity were included. Prospero ID: CRD42016035454. RESULTS: Eighty-nine papers were included. Five major themes and 28 sub-themes were identified, encompassing: (1) patient physical and psychological capability to perform physical activity, including delirium, sedation, illness severity, comorbidities, weakness, anxiety, confidence and motivation; (2) safety influences, including physiological stability and concern for lines, e.g. risk of dislodgement; (3) culture and team influences, including leadership, interprofessional communication, administrative buy-in, clinician expertise and knowledge; (4) motivation and beliefs regarding the benefits/risks; and (5) environmental influences, including funding, access to rehabilitation programs, staffing and equipment. CONCLUSIONS: The main barriers identified were patient physical and psychological capability to perform physical activity, safety concerns, lack of leadership and ICU culture of mobility, lack of interprofessional communication, expertise and knowledge, and lack of staffing/equipment and funding to provide rehabilitation programs. Barriers and enablers are multidimensional and span diverse factors. The majority of these barriers are modifiable and can be targeted in future clinical practice

Environmental conditions during mass mortalities of the ascidian Pyura stolonifera (Heller) in the Tsitsikamma Marine Protected area

Mass mortalities of the ascidian Pyura stolonifera occurred along the Tsitsikamma  coast in May 1991 and again in February 2012, following infection of large proportions of the population with a white microbial growth. P. stolonifera appeared to be the only species affected, with the outer tunic the main site of infection. No signs of pollution or algal blooms were observed, but large variations in climatic conditions were associated with both events. The 1991 mortalities occurred during a warm spell in autumn, when there was a rapid increase in the daily air temperatures. Similarly, the February 2012 event occurred after abnormally high air temperatures of January 2012 declined sharply due to a cold-water upwelling event in early February. These findings are compared with those of other marine disease and mortality studies.Key words: air and sea temperatures, disease, mortality, marine invertebrate

Temporal changes in the macrobenthos of sandprawn (Callichirus kraussi) beds in Swartvlei Estuary, South Africa

Water quality was recorded quarterly along the length of the Swartvlei estuary (2002–2014), while seagrass biomass and macrobenthic abundance were measured annually in intertidal sandprawn beds (2009–2014). Despite relatively stable, marine-dominated conditions the abundance of the sandprawn Callichirus kraussi recorded in the lower and middle reaches decreased significantly (p < 0.025), accompanied by an increase in seagrass biomass and the abundance of burrowing bivalves and the surface-grazing gastropod Nassarius kraussianus. No significant changes were noted in the upper reaches, where, unlike the lower and middle reaches, the size distribution and juvenile recruitment of C. kraussi remained relatively constant. The temporal data from the lower reaches showed a high, negative correlation between C. kraussi numbers and (a) seagrass (Zostera (Zosterella) capensis) biomass (r = −0.85), and (b) burrowing bivalve numbers (r = −0.69). These relationships were apparent in comparative samples taken from prawn and seagrass beds, where C. kraussi numbers were significantly lower and burrowing bivalve numbers were higher in a seagrass area than in the adjoining high-density prawn bed. These changes accord with previously demonstrated negative correlations between vegetation of sandbanks and abundance of C. kraussi, and with the demonstrable negative effects of sandprawns on bivalves and N. kraussianus. However, our study is novel in that it indicated that changes in enviromental conditions may shift the balance among these species.Keywords: burrowing bivalves, interactions, recruitment, seagrass, Zostera capensi

Assessments of occurrence and distribution of mammals in forests of the Garden Route National Park based on camera trapping

Eleven mammal census sites were selected in four different Afrotemperate Forest types in the Garden Route National Park, South Africa. At each site, an array of eight camera traps was deployed along trails for between 28 and 45 days. Based on accumulation curves, this was generally sufficient for recording most of the focal mammal species at each site. Only 12 mammal (≥ 1 kg) species were recorded, two of which were primarily wetland species. The most widely captured taxa were bushbuck, Tragelaphus scriptus (all 11 sites); and caracal, Caracal caracal (10 sites). The most frequently photographed species were bushbuck (40%) and chacma baboon, Papio ursinus (22%). The number of species and total capture rates did not differ (P > 0.10) between dry (scrub and high) forests and moist (medium-moist to wet) forests, or between small (< 41 km²) forests and a large forest complex. However, at species level, the capture rates of caracal and vervet monkey, Chlorocebus pygerythus; were significantly lower (P ≤ 0.05) in the large forest complex than in small forests, whilst those of bushpig, Potamochoerus larvatus; were higher. Trapping cycles of between 28 and 45 days, which recorded the highest number of threatened and protected South African species, were from small forests. Conservation implications: The role of small forests in the conservation of mammals in the Garden Route National Park should be investigated further, because relatively high numbers of threatened and protected South African mammal species were recorded in these locations