Risk factors for tuberculosis among close IGRA-negative contacts of persons with infectious tuberculosis in Singapore.

OBJECTIVES: Contacts of patients with infectious tuberculosis (TB) testing positive on interferon-gamma release assay (IGRA) are followed up to exclude active disease. However, identifying factors that predispose IGRA-negative contacts to TB could improve screening and follow-up strategies in a medium TB burden country such as Singapore. METHODS: We conducted a retrospective study of IGRA-negative contacts aged ≥2 years identified during contact investigation between January 2014 and December 2022. We examined the risk factors associated with developing active TB among contacts previously testing IGRA-negative, using univariate and multivariable logistic regression and odds ratios with 95% confidence intervals. RESULTS: Of 60,377 IGRA-negative contacts, 150 developed TB disease, and half were notified within 23 months of index patient diagnosis. IGRA-negative contacts of a smear-positive index patient were more likely to develop TB. Independent risk factors for TB were age >50 years, Malay ethnicity, having diabetes or end-stage renal failure, a "family" relationship with the index patient, or exposure in a dormitory or nursing home. CONCLUSIONS: Identifying risk factors could help optimise follow-up strategies and preventive treatment in IGRA-negative individuals. The incidence rate of TB in this group was 150 per 100,000 population, substantially higher than in the community, with a median 92 weeks to develop disease. Findings suggest that follow-up should be extended to 24 months for contacts with these risk factors.

The yield of tuberculosis contact investigation on relapsed TB patients and analysis of associated risk factors: Singapore's experience.

The yield of contact investigation on relapsed tuberculosis (TB) cases can guide strategies and resource allocation in the TB control programme. We conducted a retrospective cohort study to review the yield of contact investigation in relapsed TB cases and identify factors associated with TB infection (TBI) among close contacts of relapsed TB cases notified between 2018 and 2022 in Singapore. TB infection positivity was higher among contacts of relapsed cases which were culture-positive for Mycobacterium tuberculosis complex compared to those who were only polymerase chain reaction (PCR)-positive (14.8% vs. 12.3%). On multivariate analysis, after adjusting for age and gender of the index, gender, and existing comorbidities of contacts, factors independently associated with TBI were culture and smear positivity of the index (AOR 1.41, 95%CI 1.02-1.94), higher odds with every 10 years of increase in age compared to contacts below aged 30, contacts who were not Singapore residents (AOR 2.09, 95%CI 1.46-2.97), and household contacts (AOR 2.19, 95%CI 1.44-3.34). Although the yield of screening was higher for those who were culture-positive compared to only PCR-positive relapsed cases, contact tracing for only PCR-positive cases may still be important in a country with moderate TB incidence, should resources allow.

SIR Flat CAP (Safety In Radiology - Flat-Packed Compact Airborne Precaution): A Low-Cost, Portable, Negative-Pressure Isolation Barrier Shield for Protecting Frontline Healthcare Workers.

Introduction Multiple barrier shields have been described since the start of the COVID-19 pandemic. Most of these are bulky and designed for use in the main anesthetic or radiology departments. We developed a portable, negative-pressure barrier shield designed specifically for portable ultrasound examinations. A novel supine cough generation model was developed together with a reverse qualitative fit test to simulate real-world aerosol droplet generation and dispersion for evaluating the effectiveness of the barrier shield. We report the technical specifications of this design, named "SIR Flat CAP" from Safety In Radiology - Flat-packed Compact Airborne Precaution, as well as its performance in reducing the spread of droplets and aerosols.  Methods The barrier shield was constructed using 1 mm acrylic panels, clear packing tape, foam double-sided tape, and surgical drapes. Negative pressure was provided via hospital wall suction. A supine cough generation model was developed to simulate cough droplet dispersal. A reverse qualitative fit test was used to assess for airborne transmission of microdroplets. Results The supine cough generation model was able to replicate similar results to previously reported supine human cough generation dispersion. The use of the barrier shield with negative-pressure suction prevented the escape of visible droplets, and no airborne microdroplets were detected by reverse qualitative fit testing from the containment area. Conclusions The barrier shield significantly reduces the escape of visible and airborne droplets from the containment area, providing an additional layer of protection to front-line sonographers.

Implementation of national whole-genome sequencing of Mycobacterium tuberculosis, National Public Health Laboratory, Singapore, 2019-2022.

The National Tuberculosis Programme (NTBP) monitors the occurrence and spread of tuberculosis (TB) and multidrug-resistant TB (MDR-TB) in Singapore. Since 2020, whole-genome sequencing (WGS) of Mycobacterium tuberculosis isolates has been performed at the National Public Health Laboratory (NPHL) for genomic surveillance, replacing spoligotyping and mycobacterial interspersed repetitive unit-variable number tandem repeats analysis (MIRU-VNTR). Four thousand three hundred and seven samples were sequenced from 2014 to January 2023, initially as research projects and later developed into a comprehensive public health surveillance programme. Currently, all newly diagnosed culture-positive cases of TB in Singapore are prospectively sent for WGS, which is used to perform lineage classification, predict drug resistance profiles and infer genetic relationships between TB isolates. This paper describes NPHL's operational and technical experiences with implementing the WGS service in an urban TB-endemic setting, focusing on cluster detection and genomic drug susceptibility testing (DST). Cluster detection: WGS has been used to guide contact tracing by detecting clusters and discovering unknown transmission networks. Examples have been clusters in a daycare centre, housing apartment blocks and a horse-racing betting centre. Genomic DST: genomic DST prediction (gDST) identifies mutations in core genes known to be associated with TB drug resistance catalogued in the TBProfiler drug resistance mutation database. Mutations are reported with confidence scores according to a standardized approach referencing NPHL's internal gDST confidence database, which is adapted from the World Health Organization (WHO) TB drug mutation catalogue. Phenotypic-genomic concordance was observed for the first-line drugs ranging from 2959/2998 (98.7 %) (ethambutol) to 2983/2996 (99.6 %) (rifampicin). Aspects of internal database management, reporting standards and caveats in results interpretation are discussed.

Short-term Weight Trajectory of Severely Obese Individuals With and Without Pathogenic Satiety-Regulation Melanocortin 3/4 Receptor (MC3/4R) Mutations From a Multi-ethnic Asian Large Bariatric Surgery Program.

The melanocortin (3 or 4) receptor (MC3/4R) is involved in regulating satiety and body weight. Therefore, pathogenic mutation in MC3/4R is associated with severe obesity, for which bariatric surgery is one of the treatment options. However, there is limited data on whether individuals with MC3/4R mutation will have differential weight response to surgery, especially among the Asian populations-the epi-center of the evolving global obesity epidemic. From our large prospective Obesity-Metabolism & Intervention Cohort Study (OMICS; N = 654, recruited between 2007 and 2022), 5 individuals with pathogenic MC3/4R mutations ("case") were identified using candidate-genes panel next-generation sequencing (Illumina iSeq). These subjects were carefully propensity score-matched (baseline body mass index [BMI], age, sex, ethnicity, proportion with diabetes, type of bariatric surgery) in a 1:4 ratio to other controls. We performed linear mixed model analysis (for repeated measurements) to compare their longitudinal weight trajectories (percentage total weight loss, %TWL) over 12 months. The 5 cases with MC3/4R mutations were 48 ± 11 years, BMI 40.8 ± 11.2 kg/m2, 60% with diabetes, and all males. Their weight at baseline (pre-op), and 6 months and 12 months after surgery were 120 ± 38, 100 ± 31, and 101 ± 30 kg, respectively. Compared with propensity score-matched controls (N = 20), linear mixed model analysis suggested no difference in surgically induced %TWL (ß coefficient = -5.8 ± 3.7, P = .13) over 12 months between the groups. Therefore, we conclude that rare pathogenic MC3/4R mutations do not significantly modify weight change (%TWL) in response to bariatric surgery.

Association of Baseline Triglyceride-Glucose Index with Poor Glycemic Control and Diabetes Remission After Metabolic Surgery.

PURPOSE: The utility of insulin resistance (IR) as a predictor of diabetes remission after metabolic surgery is not well-defined. We assessed the association of baseline surrogate IR indices including triglyceride-glucose (TyG) index and homeostatic model assessment for IR (HOMA-IR) with glycemic control and diabetes remission after metabolic surgery. MATERIALS AND METHODS: Patients with type 2 diabetes scheduled for metabolic surgery were recruited at a single-center (n = 149; age: 44 ± 10 years, 47.7% men, body mass index: 41.5 ± 7.5 kg/m2), and followed-up for 12 months postoperatively. The relationships between the IR indices and poor glycemic control (HbA1c ≥ 7%) at baseline or complete diabetes remission (HbA1c < 6% without glucose-lowering medications at 12 months) post-surgery were examined. RESULTS: Elevated TyG index was associated with poor glycemic control cross-sectionally. Compared with non-remitters, lower baseline TyG index levels were observed in individuals with complete diabetes remission after surgery (P = 0.012); whereas HOMA-IR was not significantly different. Consistently, the proportion of diabetes non-remitters (compared to remitters) increased with increasing TyG tertiles from 1 to 3 (P = 0.015). Both TyG index (relative risk = 0.62, 95% CI = 0.42-0.91, P = 0.014) and TyG tertile 1 (relative risk = 1.99, 95% CI = 1.25-3.24, P = 0.003) independently predicted diabetes remission. The TyG index identified diabetes remission with an area under the curve of 0.68. The optimal TyG threshold was 9.41, yielding a sensitivity of 69.6%, specificity of 60.9%, positive predictive value of 64.0%, and negative predictive value of 66.7%. CONCLUSION: TyG index, previously suggested to predominantly reflect muscle IR, outperforms HOMA-IR as an IR indicator associated with glycemic control and diabetes remission after metabolic surgery.

Survival and complications with a surgical approach in advanced hypopharyngeal cancer.

BACKGROUND AND OBJECTIVES: The treatment paradigm for advanced hypopharyngeal cancer has shifted from surgical approaches to organ preservation. However, recent studies indicated that surgical approaches may be associated with better survival rates. This study aimed to conduct a head-to-head comparison of survival outcomes and complications with surgical versus nonsurgical approaches using a nationwide database. METHODS: Using a nationwide data set, we gathered 2196 propensity score-matched patients with stage III/IVa hypopharyngeal cancer. We compared survival rates and complications among patients with surgical and nonsurgical cancer treatment. RESULTS: Patients with stage III and IVa hypopharyngeal cancer who underwent initial surgery had significantly better 5-year overall survival and disease-free survival rates compared to their nonsurgical counterparts. There were no significant differences in long-term complications with regard to swallowing. CONCLUSIONS: These results suggest that patients who underwent initial surgery for advanced hypopharyngeal cancers had better survival rates and equivalent long-term function.

Paterson-Brown Kelly Syndrome (also commonly known as Plummer-Vinson Syndrome).

The dysphagia in this condition is usually associated with iron deficiency anemia and esophageal webs. Iron supplementation and regular surveillance are required for monitoring of malignant transformation into esophageal squamous cell carcinoma.

Fever Patterns, Cytokine Profiles, and Outcomes in COVID-19.

BACKGROUND: Prolonged fever is associated with adverse outcomes in dengue viral infection. Similar fever patterns are observed in COVID-19 with unclear significance. METHODS: We conducted a hospital-based case-control study of patients admitted for COVID-19 with prolonged fever (fever >7 days) and saddleback fever (recurrence of fever, lasting <24 hours, after defervescence beyond day 7 of illness). Fever was defined as a temperature of ≥38.0°C. Cytokines were determined with multiplex microbead-based immunoassay for a subgroup of patients. Adverse outcomes were hypoxia, intensive care unit (ICU) admission, mechanical ventilation, and mortality. RESULTS: A total of 142 patients were included in the study; 12.7% (18/142) of cases had prolonged fever, and 9.9% (14/142) had saddleback fever. Those with prolonged fever had a median duration of fever (interquartile range [IQR]) of 10 (9-11) days for prolonged fever cases, while fever recurred at a median (IQR) of 10 (8-12) days for those with saddleback fever. Both prolonged (27.8% vs 0.9%; P < .01) and saddleback fever (14.3% vs 0.9%; P = .03) were associated with hypoxia compared with controls. Cases with prolonged fever were also more likely to require ICU admission compared with controls (11.1% vs 0.9%; P = .05). Patients with prolonged fever had higher induced protein-10 and lower interleukin-1α levels compared with those with saddleback fever at the early acute phase of disease. CONCLUSIONS: Prolonged fever beyond 7 days from onset of illness can identify patients who may be at risk of adverse outcomes from COVID-19. Patients with saddleback fever appeared to have good outcomes regardless of the fever.

Metabolic Surgery Diabetes Remission (MDR) Score: a New Preoperative Scoring System for Predicting Type 2 Diabetes Remission at 1 Year After Metabolic Surgery in the Singapore Multi-ethnic Asian Setting.

PURPOSE: The utility of available scoring systems for type 2 diabetes (T2D) remission prediction after metabolic surgery has not been defined in a multi-ethnic Asian population like Singapore. We sought to assess the predictive performance of the Asia-developed ABCD scoring system for T2D remission after metabolic surgery, and develop a new algorithm to improve prediction. MATERIALS AND METHODS: We conducted a retrospective analysis of adults with T2D who underwent either Roux-en-Y gastric bypass or sleeve gastrectomy between 2007 and 2018, and followed for 1 year postoperatively (n = 114, mean age 46 ± 9 years, 48.2% men, body mass index 40.1 ± 6.6 kg/m2). The primary outcome was complete T2D remission defined as HbA1c < 6% without the use of anti-diabetic medication at 1 year after surgery. RESULTS: Complete T2D remission was observed in 47.4% of subjects at 1 year post-surgery. Stepwise logistic regression identified preoperative age, T2D duration, HbA1c, and ß-cell function (estimated by the homeostasis model) as predictors of complete T2D remission. Based on these four variables, we constructed a new 10-point scoring system named Metabolic surgery Diabetes Remission (MDR) score. Compared with ABCD, MDR produced fewer misclassifications at the mid-high scores, achieving a predictive accuracy of 71-100% at 6 points and above. In addition, MDR achieved a higher area under the receiver operating characteristic curve than ABCD for the primary outcome (0.79 versus 0.67, P = 0.007). CONCLUSION: MDR may serve as a useful clinical scoring system for predicting short-term T2D remission after metabolic surgery in Singapore's multi-ethnic Asian cohort.

The Impact of Nurses' Uniforms on Nurse-Patient Interactions: Patients' Perspectives.

OBJECTIVES: The aim of this study was to explore patients' perceptions toward the nursing uniforms used in a hospital in Singapore and how different uniforms impact nurse-patient interactions. BACKGROUND: Nursing uniforms act as a form of nonverbal communication. However, implications of the increasing variety of nursing uniforms on patients' perceptions of nurses and nurse-patient interactions are unexplored. METHODS: An exploratory qualitative study design using semistructured interviews was adopted for the study. Twenty-one patients agreed to be interviewed. An audio recorder was used during data collection. The thematic analysis method was used for data analysis. RESULTS: Four major themes were identified: identity, subjectivity, suitability, and inconsequential. Nurses' uniform was regarded as a representation of identity. Suitability of the uniform for nurses was a main concern for patients. However, nurses' uniforms were inconsequential to nurse-patient interactions. CONCLUSION: Patients' perceptions of nurses' uniforms were highly subjective and have no substantial impact on nurse-patient interactions.

Ubiquitin ligase RNF8 suppresses Notch signaling to regulate mammary development and tumorigenesis.

The E3 ubiquitin ligase RNF8 plays critical roles in maintaining genomic stability by promoting the repair of DNA double-strand breaks (DSBs) through ubiquitin signaling. Abnormal activation of Notch signaling and defective repair of DSBs promote breast cancer risk. Here, we found that low expression of the full-length RNF8 correlated with poor prognosis for breast cancer patients. Our data revealed that in addition to its role in the repair of DSBs, RNF8 regulated Notch1 signaling and cell-fate determination of mammary luminal progenitors. Mechanistically, RNF8 acted as a negative regulator of Notch signaling by ubiquitylating the active NOTCH1 protein (N1ICD), leading to its degradation. Consistent with abnormal activation of Notch signaling and impaired repair of DSBs in Rnf8-mutant mammary epithelial cells, we observed increased risk of mammary tumorigenesis in mouse models for RNF8 deficiency. Notably, deficiency of RNF8 sensitized breast cancer cells to combination of pharmacological inhibitors of Notch signaling and poly(ADP-ribose) polymerase (PARP), suggesting implications for treatment of breast cancer associated with impaired RNF8 expression or function.

Correlation of clinical illness with viremia in Zika virus disease during an outbreak in Singapore.

BACKGROUND: The first autochthonous Zika virus (ZIKV) outbreak in Singapore was detected in August 2016. We report an analysis of the correlation of clinical illness with viremia and laboratory parameters in this Asian cohort. METHODS: We conducted a prospective longitudinal cohort study of patients with a positive blood ZIKV polymerase chain reaction (PCR) result who were admitted to Tan Tock Seng Hospital, Singapore, for isolation and management. RESULTS: We included 40 patients in our study. Rash was present in all patients, while 80% (32/40) had fever, 62.5% (25/40) myalgia, 60% (24/40) conjunctivitis and 38% (15/40) arthralgia. The median duration of viremia was 3.5 days (IQR: 3-5 days). Patients with viremia of ≥4 days were more likely to have prolonged fever compared to those with viremia of less than 4 days (95% versus 63%, p = 0.01), but had no significant correlation with other clinical signs and symptoms, or laboratory investigations. However, 21 patients (53%) had hypokalemia despite the absence of gastrointestinal symptoms. CONCLUSION: Although fever correlated with duration of viremia, 30% of patients remained viremic despite defervescence. Laboratory abnormalities such as leukopenia or thrombocytopenia were not prominent in this cohort but about half the patients were noted to have hypokalemia.

Environmental colonization and onward clonal transmission of carbapenem-resistant Acinetobacter baumannii (CRAB) in a medical intensive care unit: the case for environmental hygiene.

Background: In May 2015, we noticed an increase in carbapenem-resistant Acinetobacter baumannii (CRAB) infections in the Medical Intensive Care Unit (MICU). To investigate this, we studied the extent of environmental contamination and subsequent onward clonal transmission of CRAB. Methods: We conducted a one-day point prevalence screening (PPS) of the patients and environment in the MICU. We screened patients using endotracheal tube aspirates and swabs from nares, axillae, groin, rectum, wounds, and exit sites of drains. We collected environmental samples from patients' rooms and environment outside the patients' rooms. CRAB isolates from the PPS and clinical samples over the subsequent one month were studied for genetic relatedness by whole genome sequencing (WGS). Results: We collected 34 samples from seven patients and 244 samples from the environment. On the day of PPS, we identified 8 CRAB carriers: 3 who screened positive and 5 previously known clinical infections. We detected environmental contamination in nearly two-thirds of the rooms housing patients with CRAB. WGS demonstrated genetic clustering of isolates within rooms but not across rooms. We analysed 4 CRAB isolates from clinical samples following the PPS. One genetically-related CRAB was identified in the respiratory sample of a patient with nosocomial pneumonia, who was admitted to the MICU five days after the PPS. Conclusion: The extensive environmental colonization of CRAB by patients highlights the importance of environmental hygiene. The transmission dynamics of CRAB needs further investigation.

An Evaluation of a Factor Xa-Based Clotting Time Test for Enoxaparin: A Proof-of-Concept Study.

A well-accepted test for monitoring anticoagulation by enoxaparin is not currently available. As inadequate dosing may result in thrombosis or bleeding, a clinical need exists for a suitable test. Previous in silico and in vitro studies have identified factor Xa as an appropriate activating agent, and the phospholipid Actin FS as a cofactor for a Xa clotting time (TenaCT) test. A proof-of-concept study was designed to (1) explore the reproducibility of the TenaCT test and (2) explore factors that could affect the performance of the test. In vitro clotting time tests were carried out using plasma from 20 healthy volunteers. The effect of enoxaparin was determined at concentrations of 0.25, 0.50, and 1.0 IU/mL. Clotting times for the volunteers were significantly prolonged with increasing enoxaparin concentrations. Clotting times were significantly shortened for frozen plasma samples. No significant differences in prolongation of clotting times were observed between male and female volunteers or between the 2 evaluated age groups. The clotting times were consistent between 2 separate occasions. The TenaCT test was able to distinguish between the subtherapeutic and therapeutic concentrations of enoxaparin. Plasma should not be frozen prior to performing the test, without defining a frozen plasma reference range. This study provided proof-of-concept for a Xa-based test that can detect enoxaparin dose effects, but additional studies are needed to further develop the test.

The Significance of Prolonged and Saddleback Fever in Hospitalised Adult Dengue.

Dengue fever is gaining importance in Singapore with an increase in the number of cases and mortality in recent years. Although prolonged and saddleback fever have been reported in dengue fever, there are no specific studies on their significance in dengue. This study aims to examine the prevalence of prolonged and saddleback fever in dengue as well as their associations with dengue severity. A total of 2843 polymerase-chain reaction (PCR) confirmed dengue patients admitted to Tan Tock Seng Hospital from 2004 to 2008 were included in the study. Sixty-nine percent of them were male with a median age of 34 years. Prolonged fever (fever > 7 days duration) was present in 572 (20.1%) of patients. Dengue hemorrhagic fever (DHF), dengue shock syndrome (DSS) and severe dengue (SD) were significantly more likely to occur in patients with prolonged fever. Mucosal bleeding, anorexia, diarrhea, abdominal pain, nausea or vomiting, lethargy, rash, clinical fluid accumulation, hepatomegaly, nosocomial infection, leukopenia, higher neutrophil count, higher hematocrit, higher alanine transaminase (ALT) and aspartate transaminase (AST), higher creatinine, lower protein and prolonged activated partial thromboplastin time (APTT) were significantly associated with prolonged fever but not platelet count or prothrombin time (PT). Saddleback fever was present in 165 (5.8%). Although DHF and SD were more likely to occur in patients in those with saddleback fever, DSS was not. Compared with prolonged fever, saddleback fever did not show many significant associations except for diarrhea, abdominal pain, clinical fluid accumulation, hematocrit and platelet change, and lower systolic blood pressure. This study demonstrates that prolonged fever may be associated with various warning signs and more severe forms of dengue (SD, DSS, DHF), while saddleback fever showed associations with DHF and SD but not DSS. The presence of prolonged or saddleback fever in dengue patients should therefore prompt detailed evaluation for complications of dengue, as well as early investigation to evaluate for development of nosocomial infection.