Comparison of tet(X4)-containing contigs assembled from metagenomic sequencing data with plasmid sequences of isolates from a cohort of healthy subjects

Recently discovered tet(X) gene variants have provided new insights into microbial antibiotic resistance mechanisms and their potential consequences for public health. This study focused on detection, analysis, and characterization of Tet(X4)-positive Enterobacterales from the gut microbiota of a healthy cohort of individuals in Singapore using cultivation-dependent and cultivation-independent approaches. Twelve Tet(X4)-positive Enterobacterales strains that were previously obtained from the cohort were fully genome-sequenced and comparatively analyzed. A metagenomic sequencing (MS) data set of the same samples was mined for contigs that harbored the tet(X4) resistance gene. The sequences of tet(X4)-containing contigs and plasmids sequences were compared. The presence of the resistance genes floR and estT (previously annotated as catD) was detected in the same cassette in 10 and 12 out of the 12 tet(X4)-carrying plasmids, respectively. MS detected tet(X4)-containing contigs in 2 out of the 109 subjects, while cultivation-dependent analysis previously reported a prevalence of 10.1%. The tet(X4)-containing sequences assembled from MS data are relatively short (~14 to 33 kb) but show high similarity to the respective plasmid sequences of the isolates. Our findings show that MS can complement efforts in the surveillance of antibiotic resistance genes for clinical samples, while it has a lower sensitivity than a cultivation-based method when the target organism has a low abundance. Further optimization is required if MS is to be utilized in antibiotic resistance surveillance.IMPORTANCEThe global rise in antibiotic resistance makes it necessary to develop and apply new approaches to detect and monitor the prevalence of antibiotic resistance genes in human populations. In this regard, of particular interest are resistances against last-resort antibiotics, such as tigecycline. In this study, we show that metagenomic sequencing can help to detect high abundance of the tigecycline resistance gene tet(X4) in fecal samples from a cohort of healthy human subjects. However, cultivation-based approaches currently remain the most reliable and cost-effective method for detection of antibiotic-resistant bacteria.

Mutual Exclusion of Methanobrevibacter Species in the Human Gut Microbiota Facilitates Directed Cultivation of a Candidatus Methanobrevibacter Intestini Representative

Methanogenic Archaea (methanogens) are a phylogenetically diverse group of microorganisms and are considered to be the most abundant archaeal representatives in the human gut. However, the gut methanogen diversity of human populations in many global regions remains poorly investigated. Here, we report the abundance and diversity of gut methanogenic Archaea in a multi-ethnic cohort of healthy Singaporeans by using a concerted approach of metagenomic sequencing, 16S rRNA gene amplicon sequencing, and quantitative PCR. Our results indicate a mutual exclusion of Methanobrevibacter species, i.e., the highly prevalent Methanobrevibacter smithii and the less prevalent Candidatus Methanobrevibacter intestini in more than 80% of the samples when using an amplicon sequencing-based approach. Leveraging on this finding, we were able to select a fecal sample to isolate a representative strain, TLL-48-HuF1, for Candidatus Methanobrevibacter intestini. The analyzed physiological parameters of M. smithii DSM 861T and strain TLL-48-HuF1 suggest high similarity of the two species. Comparative genome analysis and the mutual exclusion of the Methanobrevibacter species indicate potentially different niche adaptation strategies in the human host, which may support the designation of Candidatus M. intestini as a novel species. IMPORTANCE Methanogens are important hydrogen consumers in the gut and are associated with differing host health. Here, we determine the prevalence and abundance of archaeal species in the guts of a multi-ethnic cohort of healthy Singapore residents. While Methanobrevibacter smithii is the most prevalent and abundant methanogen in the human gut of local subjects, the recently proposed Candidatus Methanobrevibacter intestini is the abundant methanogen in a minority of individuals that harbor them. The observed potential mutual exclusion of M. smithii and Ca. M. intestini provides further support to the proposal that the two physiologically similar strains may belong to different Methanobrevibacter species.

Contrasting SARS-CoV-2 epidemics in Singapore: cohort studies in migrant workers and the general population

Importance

Since January 2020, Singapore has implemented comprehensive measures to suppress SARS-CoV-2. Despite this, the country has experienced contrasting epidemics, with limited transmission in the community and explosive outbreaks in migrant worker dormitories.

Objective

To estimate SARS-CoV-2 infection incidence among migrant workers and the general population in Singapore.

Design

Prospective serological cohort studies.

Setting

Two cohort studies — in a migrant worker dormitory and in the general population in Singapore.

Participants

478 residents of a SARS-CoV-2-affected migrant worker dormitory were followed up between May and July 2020, with blood samples collected on recruitment and after 2 and 6 weeks. In addition, 937 community-dwelling adult Singapore residents, for whom pre-pandemic sera were available, were recruited. These individuals also provided a serum sample on recruitment in November/December 2020.

Exposure

Exposure to SARS-CoV-2 in a densely populated migrant worker dormitory and in the general population.

Main outcomes and measures

The main outcome measures were the incidences of SARS-CoV-2 infection in migrant workers and in the general population, as determined by the detection of neutralizing antibodies against SARS-CoV-2, and adjusting for assay sensitivity and specificity using a Bayesian modeling framework.

Results

No evidence of community SARS-CoV-2 exposure was found in Singapore prior to September 2019. It was estimated that < 2 per 1000 adult residents in the community were infected with SARS-CoV-2 in 2020 (cumulative seroprevalence: 0.16%; 95% CrI: 0.008–0.72%). Comparison with comprehensive national case notification data suggested that around 1 in 4 infections in the general population were associated with symptoms. In contrast, in the migrant worker cohort, almost two-thirds had been infected by July 2020 (cumulative seroprevalence: 63.8%; 95% CrI: 57.9–70.3%); no symptoms were reported in almost all of these infections.

Conclusions and relevance

Our findings demonstrate that SARS-CoV-2 suppression is possible with strict and rapid implementation of border restrictions, case isolation, contact tracing, quarantining, and social-distancing measures. However, the risk of large-scale epidemics in densely populated environments requires specific consideration in preparedness planning. Prioritization of these settings in vaccination strategies should minimize the risk of future resurgences and potential spillover of transmission to the wider community.

Cancer Screening Knowledge and Behavior in a Multi-Ethnic Asian Population: The Singapore Community Health Study

Background

Cancer has become the leading cause of mortality in Singapore and among other Asian populations worldwide. Despite the presence of National Cancer Screening programmes in Singapore, less than half of the population has had timely screening according to guidelines. The underlying factors of poor cancer screening rates and health outcomes among Asian ethnic groups remain poorly understood. We therefore examined cancer screening participation rates and screening behavior in a multi-ethnic Singapore population.

Methods

We collected data from 7,125 respondents of the 2015–2016 Singapore Community Health Study. Factors associated with cervical, breast, and colorectal cancer screening were evaluated using modified Poisson regression. Adjusted prevalence ratios were computed with 95% confidence intervals after adjusting for confounders.

Results

The mean age of the respondents was 57.7 ± 10.9 years; 58.9% were female and were predominately Chinese (73.0%), followed by Malay (14.2%), and Indian (10.9%). Less than half of the respondents in the recommended age groups had undergone cancer screening (cervical, 43%; breast, 35.1%; colorectal, 27.3%). Malay respondents were significantly less likely to screen as recommended for cervical (aPR = 0.75, CI = 0.65–0.86, p < 0.001), breast (aPR = 0.83, CI = 0.68–0.99, p = 0.045), and colorectal cancer (aPR = 0.55, CI = 0.44–0.68, p < 0.001), as compared to Chinese respondents. Respondents who had obtained lower secondary level education were 42% more likely to screen for cervical cancer (aPR = 1.42, CI = 1.23–1.64, p < 0.001), and 22% more likely to screen for breast cancer (aPR = 1.22, CI = 1.02–1.46, p = 0.032), compared to those with primary level education and below. Respondents with a household income ≥S$10,000/month were 71% more likely to screen for breast cancer (aPR = 1.71, CI = 1.37–2.13, p < 0.001), as compared with <$2,000/month.

Conclusions

Ethnicity and socio-economic status were significantly associated with lower uptake of cancer screening tests in Singapore. To improve the screening uptake among disadvantaged groups, a multi-faceted approach is needed that addresses the barriers to screening such as the adequacy of subsidy schemes and ethnic differences.

Emergence of tigecycline- and eravacycline-resistant Tet(X4)-producing Enterobacteriaceae in the gut microbiota of healthy Singaporeans

OBJECTIVES

The recently discovered tigecycline-inactivating enzyme Tet(X4) can confer high-level tigecycline resistance on its hosts, which makes it a public health concern. This study focused on isolation and screening of Tet(X4)-positive Enterobacteriaceae from the gut microbiota of a cohort of healthy individuals in Singapore.

METHODS

MinION and Illumina sequencing was performed to obtain the complete genome sequences of Escherichia coli 2EC1-1 and 94EC. Subsequently, 109 human faecal samples were screened retrospectively for eravacycline-resistant Enterobacteriaceae strains, which were further tested for tet(X4) by PCR. The taxonomy of the isolated strains was determined by 16S rRNA gene PCR and Sanger sequencing.

RESULTS

Comparative genomic analysis of E. coli 2EC1-1 and 94EC revealed that both carry tet(X4), which is encoded by IncI1-type plasmids p2EC1-1 and p94EC-2, respectively. Retrospective screening of faecal samples collected from 109 healthy individuals showed that the faecal carriage rate of Tet(X4)-producing Enterobacteriaceae is 10.1% (95% CI = 5.1%-17.3%), suggesting that tet(X4) is widely distributed in the gut microbiota of healthy individuals in Singapore.

CONCLUSIONS

To the best of our knowledge, this is the first report on the prevalence of tet(X4) in the gut microbiota of a healthy human cohort, as well as the first description of this resistance mechanism outside of China. Our findings suggest that surveillance of tet(X4) in community settings is vital to monitor the spread of this resistance mechanism.

Highly functional virus-specific cellular immune response in asymptomatic SARS-CoV-2 infection

The efficacy of virus-specific T cells in clearing pathogens involves a fine balance between antiviral and inflammatory features. SARS-CoV-2–specific T cells in individuals who clear SARS-CoV-2 without symptoms could reveal nonpathological yet protective characteristics. We longitudinally studied SARS-CoV-2–specific T cells in a cohort of asymptomatic (n = 85) and symptomatic (n = 75) COVID-19 patients after seroconversion. We quantified T cells reactive to structural proteins (M, NP, and Spike) using ELISpot and cytokine secretion in whole blood. Frequencies of SARS-CoV-2–specific T cells were similar between asymptomatic and symptomatic individuals, but the former showed an increased IFN-γ and IL-2 production. This was associated with a proportional secretion of IL-10 and proinflammatory cytokines (IL-6, TNF-α, and IL-1β) only in asymptomatic infection, while a disproportionate secretion of inflammatory cytokines was triggered by SARS-CoV-2–specific T cell activation in symptomatic individuals. Thus, asymptomatic SARS-CoV-2–infected individuals are not characterized by weak antiviral immunity; on the contrary, they mount a highly functional virus-specific cellular immune response.

Consumption of Foods With Higher Energy Intake Rates is Associated With Greater Energy Intake, Adiposity, and Cardiovascular Risk Factors in Adults

BACKGROUND

Both high energy density and fast eating rates contribute to excess energy intakes. The energy intake rate (EIR; kcal/min) combines both the energy density (kcal/g) and eating rate (g/min) of a food to quantify the typical rate at which calories of different foods are ingested.

OBJECTIVES

We describe the EIRs of diets in a multi-ethnic Asian population, and examine relationships between the consumption of high-EIR foods and total energy intake, body composition, and cardio-metabolic risk factors.

METHODS

Diet and lifestyle data from the Singapore Multi-Ethnic Cohort 2 (n = 7011; 21-75 y), were collected through interviewer-administrated questionnaires. The EIR for each of the 269 foods was calculated as the product of its eating rate and energy density. Multivariable models were used to examine associations between the relative consumption of foods with higher and lower EIRs and energy intake, body composition, and cardio-metabolic risks, after adjusting for age, sex, ethnicity, education level, physical activity, smoking status, and alcohol drinking status.

RESULTS

Individuals with higher daily energy intakes and with obesity consumed a significantly larger percentage of their energy from high-EIR foods, with a smaller relative intake of lower-EIR foods. Individuals with raised serum cholesterol also consumed a significantly higher proportion of high-EIR foods, whereas those without hypertension consumed a larger percentage of energy intake from low-EIR foods. Individuals classified as having a "very high" dietary EIR had a significantly 1.3 kg higher body weight (95% CI, 0.2-1.5; P = 0.013), 0.4 kg/m2 higher BMI (95% CI, 0.03-0.8; P = 0.037), and 1.2 cm larger waist circumference (95% CI, 0.2-2.2; P = 0.010), and were more likely to have abdominal overweight (OR, 1.3; 95% CI, 1.1-1.5; P < 0.001) than those with a "low" dietary EIR.

CONCLUSIONS

Comparing foods by their EIRs summarizes the combined impact of energy density and eating rate, and may identify foods and dietary patterns that are associated with obesogenic eating styles and higher diet-related cardiovascular disease risk in an Asian population.

Sleep Duration, Sleep Quality and Physical Activity, but Not Sedentary Behaviour, Are Associated with Positive Mental Health in a Multi-Ethnic Asian Population: A Cross-Sectional Evaluation

BACKGROUND

We assessed the associations of sleep, physical activity and sedentary behaviour with positive mental health (PMH) in the multi-ethnic population of Singapore.

METHODS

The Singapore Health 2 study is a nationally representative cross-sectional survey among residents aged 18-79 years. A PMH instrument was administered to 1925 participants to obtain total PMH and six sub-component scores. Self-rated sleep duration, sleep quality, sedentary behaviour and physical activity were assessed. Multivariable linear regression analyses were conducted.

RESULTS

The mean age of the participants was 40.1 (SD 14.3) years. Sleep duration (≥8 h/night: β = 0.17,95% CI: 0.02-0.32; 7-< 8 h/night: β = 0.17,95% CI: 0.03-0.30 versus <6 h/night, p = 0.002), sleep quality (very good: β = 0.45,95% CI: 0.29-0.60; fairly good: β = 0.20,95% CI: 0.06-0.33 versus very/fairly bad; ptrend < 0.001) and physical activity (high: β = 0.19,95% CI: 0.05-0.32; moderate: β = 0.15, 95% CI: 0.03-0.27 versus low; ptrend < 0.001) were directly associated with total PMH. Sedentary behaviour was not significantly associated with PMH. Sleep duration, sleep quality and physical activity were directly associated with the PMH sub-components 'emotional support' and 'personal growth and autonomy'.

CONCLUSIONS

Duration and quality of sleep and physical activity were directly associated with PMH in an urban Asian population. These findings support incorporating sleep and physical activity interventions to improve population mental health.

Cohort profile: the Singapore diabetic cohort study

PURPOSE

The diabetic cohort (DC) was set up to study the determinants of complications in individuals with type 2 diabetes and examine the role of genetic, physiological and lifestyle factors in the development of complications in these individuals.

PARTICIPANTS

A total of 14 033 adult participants with type 2 diabetes were recruited from multiple public sector polyclinics and hospital outpatient clinics in Singapore between November 2004 and November 2010. The first round of follow-up was conducted for 4131 participants between 2012 and 2016; the second round of follow-up started in 2016 and is expected to end in 2021. A questionnaire survey, physical assessments, blood and urine sample collection were conducted at recruitment and each follow-up visit. The data set also includes genetic data and linkage to medical and administrative records for recruited participants.

FINDINGS TO DATE

Data from the cohort have been used to identify determinants of diabetes and related complications. The longitudinal data of medical records have been used to analyse diabetes control over time and its related outcomes. The cohort has also contributed to the identification of genetic loci associated with type 2 diabetes and diabetic kidney disease in collaboration with other large cohort studies. About 25 scientific papers based on the DC data have been published up to May 2019.

FUTURE PLANS

The rich data in DC can be used for various types of research to study disease-related complications in patients with type 2 diabetes. We plan to further investigate disease progression and new biomarkers for common diabetic complications, including diabetic kidney disease and diabetic neuropathy.

Development and validation of the Rapid Positive Mental Health Instrument (R-PMHI) for measuring mental health outcomes in the population

Background

The multidimensional Positive Mental Health Instrument (PMHI) has 47 items and six subscales. This study aimed to develop and validate a short unidimensional version of the PMHI among Singapore’s adult resident population.

Methods

Using pooled data from three earlier studies (n = 1050), PMHI items were reduced by Partial Credit Rasch Model (PCRM) runs in a random split-half sample, while psychometric properties of the resulting measure were tested through confirmatory factor analysis (CFA), item response theory-graded response model and internal consistency reliability in the other half. Its reliability, construct and concurrent validity, agreement with the original scale, floor and ceiling effect, and scale estimates were further investigated in an external representative general population sample (n = 1925).

Results

The average age of the participants was around 41 years. Four PCRM re-runs for item selection resulted in a 6-item unidimensional Rapid PMHI (R-PMHI). CFA confirmed the unidimensional structure of the R-PMHI in the internal (RMSEA = 0.075, CFI = 0.985, TLI = 0.974) and external (RMSEA = 0.051, CFI = 0.992, TLI = 0.987) validation samples. In the external validation sample, the R-PMHI met concurrent validity criteria, showing high agreement with the 47-item version with intra-class correlation coefficient of 0.872 (95% CI: 0.861 to 0.882) and low floor and ceiling effects. Weight-adjusted mean (SE, 95% CI) R-PMHI score in the population was 4.86 (0.2, 4.82–4.90).

Conclusion

The unidimensional 6-item R-PMHI offers brevity over the original multidimensional measure while appropriately representing the positive mental health construct. Prospective studies are needed to assess its responsiveness and test-retest reliability.

Epidemiology and Relative Severity of Influenza Subtypes in Singapore in the Post-Pandemic Period from 2009 to 2010

Background

After 2009, pandemic influenza A(H1N1) [A(H1N1)pdm09] cocirculated with A(H3N2) and B in Singapore.

Methods

A cohort of 760 participants contributed demographic data and up to 4 blood samples each from October 2009 to September 2010. We compared epidemiology of the 3 subtypes and investigated evidence for heterotypic immunity through multivariable logistic regression using a generalized estimating equation. To examine age-related differences in severity between subtypes, we used LOESS (locally weighted smoothing) plots of hospitalization to infection ratios and explored birth cohort effects referencing the pandemic years (1957; 1968).

Results

Having more household members aged 5–19 years and frequent public transport use increased risk of infection, while preexisting antibodies against the same subtype (odds ratio [OR], 0.61; P = .002) and previous influenza infection against heterotypic infections (OR, 0.32; P = .045) were protective. A(H1N1)pdm09 severity peaked in those born around 1957, while A(H3N2) severity was least in the youngest individuals and increased until it surpassed A(H1N1)pdm09 in those born in 1952 or earlier. Further analysis showed that severity of A(H1N1)pdm09 was less than that for A(H3N2) in those born in 1956 or earlier (P = .021) and vice versa for those born in 1968 or later (P < .001), with no difference in those born between 1957 and 1967 (P = .632).

Conclusions

Our findings suggest that childhood exposures had long-term impact on immune responses consistent with the theory of antigenic sin. This, plus observations on short-term cross-protection, have implications for vaccination and influenza epidemic and pandemic mitigation strategies.

Adequacy of public health communications on H7N9 and MERS in Singapore: insights from a community based cross-sectional study

Background

Singapore remains vulnerable to worldwide epidemics due to high air traffic with other countries This study aims to measure the public’s awareness of the Middle East Respiratory Syndrome (MERS) and Avian Influenza A (H7N9), identify population groups who are uninformed or misinformed about the diseases, understand their choice of outbreak information source, and assess the effectiveness of communication channels in Singapore.

Methods

A cross-sectional study, comprising of face-to-face interviews, was conducted between June and December 2013 to assess the public’s awareness and knowledge of MERS and H7N9, including their choice of information source. Respondents were randomly selected and recruited from 3 existing cohort studies. An opportunistic sampling approach was also used to recruit new participants or members in the same household through referrals from existing participants.

Results

Out of 2969 participants, 53.2% and 79.4% were not aware of H7N9 and MERS respectively. Participants who were older and better educated were most likely to hear about the diseases. The mean total knowledge score was 9.2 (S.D ± 2.3) out of 20, and 5.9 (S.D ± 1.2) out of 10 for H7N9 and MERS respectively. Participants who were Chinese, more educated and older had better knowledge of the diseases. Television and radio were the primary sources of outbreak information regardless of socio-demographic factors.

Conclusion

Heightening education of infectious outbreaks through appropriate media to the young and less educated could increase awareness.

Psychometric properties and population norms of the positive mental health instrument in a representative multi-ethnic Asian population

Background

Measures of mental well-being and positive mental health (PMH) have been largely developed and used in Western populations, however, data on representative Asian communities are lacking. Using data from a population sample, this study sought to establish psychometric properties and norms of the PMH Instrument (PMH-I), a measure of positive mental health developed in Singapore.

Methods

We conducted a nationally representative survey among 1925 adults aged 18–79 years of Chinese, Malay, Indian or other ethnicity. Participants reported socio-demographic characteristics and completed the PMH-I along with measures of health-related quality of life (HRQoL) and psychological distress. Construct validity of the PMH-I was assessed using confirmatory factor analysis and concurrent validity was tested through correlation with other psychological measures. Normative PMH values and differences in population subgroups were estimated.

Results

The six-factor-higher-order structure of the PMH-I comprising six subscales of general coping, emotional support, spirituality, interpersonal skills, personal growth and autonomy and global affect was confirmed. Concurrent validity was shown through significant positive correlation of the total PMH score and its subscales with HRQoL and an inverse correlation with psychological distress. Weighted age, gender and ethnicity-specific norms were derived for the Singapore population. Total PMH was significantly higher in participants aged over 40 years as compared with 18–29 year olds and in non-Chinese ethnic groups as compared with Chinese. These differences were observed for all PMH-I subscales, with the exception of emotional support and interpersonal skills score differences by age. In contrast, gender, marital status, and education level were significantly associated with some of the subscales, but not with total PMH.

Conclusions

These results support the psychometric properties of the PMH-I in a multi-ethnic Asian population sample. The generalizable population-based norms support the application of the PMH-I for measuring mental health and assessing its determinants within the Singapore general population.

Electronic supplementary material

The online version of this article (10.1186/s12874-018-0487-9) contains supplementary material, which is available to authorized users.

Vitamin D Binding Protein and Vitamin D Levels in Multi-Ethnic Population

INTRODUCTION

Low levels of 25-hydroxyvitamin D (25(OH)D) has been associated with many negative health outcomes including falls and fractures. 25(OH)D is largely bound to vitamin D binding protein (VDBP). There is increasing evidence that free or bioavailable 25(OH)D may be a better measure of vitamin D deficiency.

OBJECTIVE

To determine the prevalence of 25(OH)D deficiency and VDBP levels in multi-ethnic population, and its impact on muscle strength.

DESIGN AND METHODS

Cross-sectional study of older adults in Western region of Singapore. 295 participants from three ethnic groups were selected from the Healthy Older People Everyday (HOPE) cohort for measurements of total 25(OH)D and VDBP levels. Total 25(OH)D, VDBP, frailty status, Timed-Up-and-Go (TUG) and grip strength (GS) were assessed. Albumin, free and bioavailable 25(OH)D were only available for 256 participants.

RESULTS

53% of Malay and 55% of Indians were deficient in 25(OH)D compared with 18.2% of ethnic Chinese participants. Chinese also had higher total 25(OH)D concentrations with a mean of 29.1 ug/l, (p = <0.001). Chinese had the lowest level of VDBP (169.6ug/ml) followed by Malay (188.8 ug/ml) and Indian having the highest (220.1 ug/ml). Calculated bioavailable and free 25(OH)D levels were significantly higher in Chinese, followed by Malays and Indians, which also correlated with better grip strength measures amongst the Chinese.

CONCLUSION

The Malays and Indians had overall lower free, bioavailable and total 25(OH)D compared with ethnic Chinese. Chinese ethnic group also had the lowest VDBP and better overall grip strength.

Infectious disease transmission: survey of contacts between hospital-based healthcare workers and working adults from the general population

BACKGROUND

Healthcare workers (HCWs) may be the inadvertent interface between the healthcare setting and the community for infectious diseases transmission.

AIM

To investigate HCWs' contacts during a work day and compare these against working adults from the general population.

METHODS

Prospective survey of contacts through 24 h self-reported diary in three public sector tertiary care hospitals and community-based working adults in Singapore. Participants were HCWs and working adults from the community.

FINDINGS

In all, 211 HCWs and 1028 working adults reported a total of 4066 and 9206 contacts. HCWs reported more work-related contacts than community-based working adults (median of 13 versus 4), and more contacts that were neither household nor work-related (1 versus 0) but fewer household contacts (2 versus 3). HCWs reported more work-related contacts involving physical contacts, and more new contacts particularly with short duration (≤15 min) compared to community-based working adults. Among different HCW types, doctors reported the highest whereas ward-based nurses reported the lowest total work-related contacts. Around half of ward-based and clinic-based nurses' contacts involved physical touch. Work-related contacts reported by clinic-based nurses, doctors, and assorted HCWs were shorter than in ward-based nurses, with a substantial number effectively occurring with new contacts. Institutional effects significant on univariate analyses were much reduced and non-significant after adjusting for confounding by HCW type.

CONCLUSION

HCWs' contacts differ substantially from those of community-based working adults. HCWs may thus be at higher risk of acquiring and spreading contact-transmissible and respiratory infections due to the nature of their work. Whereas total number of contacts was fairly similar between HCW types, the characteristics of their contacts differed substantively.

Detection of viral respiratory pathogens in mild and severe acute respiratory infections in Singapore

To investigate the performance of laboratory methods and clinical case definitions in detecting the viral pathogens for acute respiratory infections (ARIs) from a prospective community cohort and hospital inpatients, nasopharyngeal swabs from cohort members reporting ARIs (community-ARI) and inpatients admitted with ARIs (inpatient-ARI) were tested by Singleplex Real Time-Polymerase Chain Reaction (SRT-PCR), multiplex RT-PCR (MRT-PCR) and pathogen-chip system (PathChip) between April 2012 and December 2013. Community-ARI and inpatient-ARI was also combined with mild and severe cases of influenza from a historical prospective study as mild-ARI and severe-ARI respectively to evaluate the performance of clinical case definitions. We analysed 130 community-ARI and 140 inpatient-ARI episodes (5 inpatient-ARI excluded because multiple pathogens were detected), involving 138 and 207 samples respectively. Detection by PCR declined with days post-onset for influenza virus; decrease was faster for community-ARI than for inpatient-ARI. No such patterns were observed for non-influenza respiratory virus infections. PathChip added substantially to viruses detected for community-ARI only. Clinical case definitions discriminated influenza from other mild-ARI but performed poorly for severe-ARI and for older participants. Rational strategies for diagnosis and surveillance of influenza and other respiratory virus must acknowledge the differences between ARIs presenting in community and hospital settings.

Evaluation of Equations for Predicting 24-Hour Urinary Sodium Excretion from Casual Urine Samples in Asian Adults

BACKGROUND

The collection of 24-h urine samples for the estimation of sodium intake is burdensome, and the utility of spot urine samples in Southeast Asian populations is unclear.

OBJECTIVE

We aimed to assess the validity of prediction equations with the use of spot urine concentrations.

METHODS

A sample of 144 Singapore residents of Chinese, Malay, and Indian ethnicity aged 18-79 y were recruited from the Singapore Health 2 Study conducted in 2014. Participants collected urine for 24 h in multiple small bottles on a single day. To determine the optimal collection time for a spot urine sample, a 1-mL sample was taken from a random bottle collected in the morning, afternoon, and evening. Published equations and a newly derived equation were used to predict 24-h sodium excretion from spot urine samples.

RESULTS

The mean ± SD concentration of sodium from the 24-h urine sample was 125 ± 53.4 mmol/d, which is equivalent to 7.2 ± 3.1 g salt. Bland-Altman plots showed good agreement at the group level between estimated and actual 24-h sodium excretion, with biases for the morning period of -3.5 mmol (95% CI: -14.8, 7.8 mmol; new equation) and 1.46 mmol (95% CI: -10.0, 13.0 mmol; Intersalt equation). A larger bias of 25.7 mmol (95% CI: 12.2, 39.3 mmol) was observed for the Tanaka equation in the morning period. The prediction accuracy did not differ significantly for spot urine samples collected at different times of the day or at a random time of day (P = 0.11-0.76).

CONCLUSION

This study suggests that the application of both our own newly derived equation and the Intersalt equation to spot urine concentrations may be useful in predicting group means for 24-h sodium excretion in urban Asian populations.