Near Field Detection and Peak Frequency Metric for Substrate and Activation Mapping of Ventricular Arrhythmias in 2- and 3-Dimensional Circuits.

BACKGROUND: Successful ventricular arrhythmia (VA) ablation requires identification of functionally critical sites during contact mapping. Estimation of the peak frequency (PF) component of the EGM may improve correct near field (NF) annotation to identify circuit segments on the mapped surface. In turn, assessment of near- and far field (FF) EGMs may delineate the 3-dimensional path of a VT circuit. METHODOLOGY: A proprietary NF detection algorithm was applied retrospectively to scar-related re-entry VT maps and compared to manually reviewed maps employing first deflection (FDcorr) for VT activation maps and last deflection (LD) for substrate maps. VT isthmus location and characteristics mapped with FDcorr vs. NF were compared. Omnipolar low voltage areas, late activating areas and deceleration zones in LD vs NF substrate maps were compared. On substrate maps, PF estimation was compared between isthmus and bystander-sites. Activation mapping with entrainment and/or VT termination with RF ablation confirmed critical sites. RESULTS: 18 patients with high-density VT activation and substrate maps (55.6% ischemic) were included. NF detection correctly located critical parts of the circuit in 77.7% of the cases compared to manually reviewed VT maps as reference. In substrate maps NF detection identified deceleration zones in 88.8% of cases which overlapped with FDcorr VT isthmus in 72.2% compared to 83.3% overlap of DZ assessed by LD. Applied to substrate maps, PF as a stand-alone feature did not differentiate VT isthmus-sites from low voltage bystander-sites. Omnipolar voltage was significantly higher at isthmus-sites with longer EGM durations compared to low voltage bystander-sites. CONCLUSION: The NF algorithm may enable rapid high-density activation mapping of VT circuits in the near field of the mapped surface. Integrated assessment and combined analysis of near and far field EGMs could support characterisation of 3-dimensional VT circuits with intramural segments. For scar-related substrate mapping, PF as a stand-alone EGM feature did not enable the differentiation of functionally critical sites of the dominant VT from low voltage bystander sites in this cohort.

Descriptive analysis of poisoning cases involving attention deficit hyperactivity disorder medications in Hong Kong.

INTRODUCTION: The number of poisoning cases involving attention deficit hyperactivity disorder (ADHD) medications has reportedly risen with their increased use. However, there is limited relevant evidence from Asia. We analysed the characteristics of poisoning events involving these medications in Hong Kong. METHODS: We retrieved data regarding ADHD medication-related poisoning cases from the Hong Kong Poison Information Centre and conducted a descriptive analysis of the demographic information and poisoning information including sources of cases, exposure reason, exposure location, and outcome. The HKPIC data were linked with the Hospital Authority Clinical Data Analysis and Reporting System (CDARS) via de-identified Accident and Emergency numbers of public hospitals to investigate clinical characteristics. We also retrieved ADHD medication prescription records from the CDARS, then compared trends between poisoning cases and ADHD medication use. RESULTS: We identified 72 poisoning cases involving ADHD medications between 2009 and 2019, of which approximately 70% occurred in the affected individual's residence; most were intentional poisoning events (65.3%). No statistically significant association was observed between ADHD medication prescription trends and poisoning events involving ADHD medications. Of the 66 cases (91.7%) successfully linked to CDARS, 40 (60.6%) occurred in individuals with ADHD (median age: 14 years); 26 (39.4%) occurred in individuals who lacked ADHD (median age: 33 years) but displayed higher rates of other mental disorders including depression and anxiety. CONCLUSION: No significant correlation was evident between ADHD medication prescriptions and poisoning events involving ADHD medications. However, medication management and caregiver education must be emphasised to prevent potential poisoning events.

Determinants of antibiotic prescribing for upper respiratory tract infections in an emergency department with good primary care access: a qualitative analysis.

Upper respiratory tract infections (URTIs) account for substantial attendances at emergency departments (EDs). There is a need to elucidate determinants of antibiotic prescribing in time-strapped EDs - popular choices for primary care despite highly accessible primary care clinics. Semi-structured in-depth interviews were conducted with purposively sampled physicians (n = 9) in an adult ED in Singapore. All interviews were analysed using thematic analysis and further interpreted using the Social Ecological Model to explain prescribing determinants. Themes included: (1) reliance on clinical knowledge and judgement, (2) patient-related factors, (3) patient-physician relationship factors, (4) perceived practice norms, (5) policies and treatment guidelines and (6) patient education and awareness. The physicians relied strongly on their clinical knowledge and judgement in managing URTI cases and seldom interfered with their peers' clinical decisions. Despite departmental norms of not prescribing antibiotics for URTIs, physicians would prescribe antibiotics when faced with uncertainty in patients' diagnoses, treating immunocompromised or older patients with comorbidities, and for patients demanding antibiotics, especially under time constraints. Participants had a preference for antibiotic prescribing guidelines based on local epidemiology, but viewed hospital policies on prescribing as a hindrance to clinical judgement. Participants highlighted the need for more public education and awareness on the appropriate use of antibiotics and management of URTIs. Organisational practice norms strongly influenced antibiotic prescribing decisions by physicians, who can be swayed by time pressures and patient demands. Clinical decision support tools, hospital guidelines and patient education targeting at individual, interpersonal and community levels could reduce unnecessary antibiotic use.

Length of stay and odds of MRSA acquisition: a dose-response relationship?

The association between methicillin-resistant Staphylococcus aureus (MRSA) colonisation and/or infection with increased morbidity and mortality among hospital patients has long been recognised. We sought to build on previous studies to identify modifiable risk factors associated with the acquisition of MRSA colonisation and infection by conducting a retrospective cohort study on patients admitted through the Emergency Department of an acute tertiary-care general hospital in Singapore which implemented universal on-admission MRSA screening. Patients were assigned to the acquisition or non-acquisition group depending on whether they acquired MRSA during their admission. We used logistic regression models with a patient being in the acquisition group as the binary outcome to identify factors associated with MRSA acquisition. A total of 1302 acquisition and 37 949 non-acquisition group patients were analysed. Fifteen variables were included in the multivariate model. A dose-response relationship between length of stay and odds of MRSA acquisition was observed, with a length of stay 3 weeks or more (Adj OR 11.78-57.36, all P < 0.001) being the single biggest predictor of MRSA acquisition. Other variables significantly associated with MRSA acquisition were: male gender, age 65 or greater, previous MRSA colonisation or infection, exposure to certain antibiotics and surgery, and history of diabetes.

Bacterial species associated with persistent apical periodontitis exert differential effects on osteogenic differentiation.

AIM: To determine if bacteria associated with persistent apical periodontitis induce species-specific pro-inflammatory cytokine responses in macrophages, and the effects of this species-specific microenvironment on osteogenic differentiation. METHODOLOGY: Macrophages were exposed to Enterococcus faecalis, Streptococcus oralis, Streptococcus mitis, Fusobacterium nucleatum, Treponema denticola or Tannerella forsythia, and levels of TNF-α and IL-1ß elicited were determined by immunoassay. Following treatment of MG-63 pre-osteoblasts with conditioned media from bacteria-exposed macrophages, osteogenic differentiation and viability of osteoblasts were analyzed by Alizarin Red Staining and MTS assay, respectively. Statistical analysis was carried out by one-way anova with the Tukey post-hoc test. Differences were considered to be significant if P < 0.05. RESULTS: Macrophages exposed to Gram-positive bacteria did not produce significant amounts of cytokines. F. nucleatum-challenged macrophages produced up to four-fold more TNF-α and IL-1ß compared to T. denticola or T. forsythia. Only conditioned media from macrophages treated with Gram-negative bacteria decreased mineralization and viability of osteoblasts. CONCLUSIONS: Gram-positive bacteria did not impact osteogenic differentiation and appeared innocuous. Gram-negative bacteria, in particular F. nucleatum elicited an enhanced pro-inflammatory response in macrophages, inhibited osteogenic differentiation and reduced cell viability. The findings suggest that the presence of this organism could potentially increase the severity of persistent apical periodontitis.

Validation of a novel mapping system and utility for mapping complex atrial tachycardias.

INTRODUCTION: This study sought to validate a novel wavefront mapping system utilizing whole-chamber basket catheters (CARTOFINDER, Biosense Webster). The system was validated in terms of (1) mapping atrial-paced beats and (2) mapping complex wavefront patterns in atrial tachycardia (AT). METHODS AND RESULTS: Patients undergoing catheter ablation for AT and persistent AF were included. A 64-pole-basket catheter was used to acquire unipolar signals that were processed by CARTOFINDER mapping system to generate dynamic wavefront propagation maps. The left atrium was paced from four sites to demonstrate focal activation. ATs were mapped with the mechanism confirmed by conventional mapping, entrainment, and response to ablation. Twenty-two patients were included in the study (16 with AT and 6 with AF initially who terminated to AT during ablation). In total, 172 maps were created with the mapping system. It correctly identified atrial-pacing sites in all paced maps. It accurately mapped 9 focal/microreentrant and 18 macroreentrant ATs both in the left and right atrium. A third and fourth observer independently identified the sites of atrial pacing and the AT mechanism from the CARTOFINDER maps, while being blinded to the conventional activation maps. CONCLUSIONS: This novel mapping system was effectively validated by mapping focal activation patterns from atrial-paced beats. The system was also effective in mapping complex wavefront patterns in a range of ATs in patients with scarred atria. The system may therefore be of practical use in the mapping and ablation of AT and could have potential for mapping wavefront activations in AF.

Intranasal octenidine and universal antiseptic bathing reduce methicillin-resistant Staphylococcus aureus (MRSA) prevalence in extended care facilities.

Intranasal octenidine, an antiseptic alternative to mupirocin, can be used for methicillin-resistant Staphylococcus aureus (MRSA) decolonisation in the prevention of nosocomial transmission. A controlled before-after study was conducted in three extended-care hospitals in Singapore. All inpatients with >48 h stay were screened for MRSA colonisation in mid-2015(pre-intervention) and mid-2016(post-intervention). Hospital A: universal daily chlorhexidine bathing throughout 2015 and 2016, with intranasal octenidine for MRSA-colonisers in 2016. Hospital B: universal daily octenidine bathing and intranasal octenidine for MRSA-colonisers in 2016. Hospital C: no intervention. In 2015, MRSA prevalence was similar among the hospitals (Hospital A: 38.5%, Hospital B: 48.1%, Hospital C: 43.4%, P = 0.288). From 2015 to 2016, MRSA prevalence reduced by 58% in Hospital A (Adj OR 0.42, 95% CI 0.20-0.89) and 43% in Hospital B (Adj OR 0.57, 95% CI 0.39-0.84), but remained similar in Hospital C (Adj OR 1.19, 95% CI 0.60-2.33), after adjusting for age, gender, comorbidities, prior MRSA carriage, prior antibiotics exposure and length of hospital stay. Compared with the change in MRSA prevalence from 2015 to 2016 in Hospital C, MRSA prevalence declined substantially in Hospital A (Adj OR 0.35, 95% CI 0.13-0.97) and Hospital B (Adj OR 0.48, 95% CI 0.22-1.03). Topical intranasal octenidine, coupled with universal daily antiseptic bathing, can reduce MRSA colonisation in extended-care facilities.

Methicillin-resistant Staphylococcus aureus colonisation: epidemiological and molecular characteristics in an acute-care tertiary hospital in Singapore.

Current knowledge of methicillin-resistant Staphylococcus aureus (MRSA) colonisation in relation to epidemiological characteristics is incomplete. We conducted a cross-sectional study at an acute-care tertiary infectious diseases hospital of MRSA isolates identified through routine surveillance from January 2009 to December 2011. We randomly selected 205 MRSA isolates (119 inpatients) from 798 isolates (427 inpatients) for molecular profiling using multilocus sequence typing. Multilevel multinomial logistic regression was used to estimate odds ratio (OR) assessing the predilection of MRSA strains for anatomic sites, and associations of strains with human immunodeficiency virus (HIV) infection. The most frequent sequence types (STs) were 239, 22 and 45. The proportion of ST22 increased over the sampling period, replacing ST239 as the dominant lineage. However, ST239 remained the most prevalent among HIV-seropositive individuals who were six times more likely to be colonised with this strain than non-HIV patients (adjusted OR (aOR) 6.44, 95% confidence interval (CI) 1.94-21.36). ST45 was >24 times more likely to be associated with perianal colonisation than in the nares, axillae and groin sites (aOR 24.20, 95% CI 1.45-403.26). This study underlines the clonal replacement of MRSA in Singapore as previously reported but revealed, in addition, key strain differences between HIV-infected and non-infected individuals hospitalised in the same environment.

Risk assessment and laboratory investigation of respiratory illness in travellers returning to Singapore 2012-2015: experience from the MERS-CoV Surveillance Programme.

Since the emergence of Middle East respiratory syndrome coronavirus (MERS-CoV), Singapore has enhanced its national surveillance system to detect the potential importation of this novel pathogen. Using the guidelines from the Singapore Ministry of Health, a suspect case was defined as a person with clinical signs and symptoms suggestive of pneumonia or severe respiratory infection with breathlessness, and with an epidemiological link to countries where MERS-CoV cases had been reported within the preceding 14 days. This report describes a retrospective review of 851 suspected MERS-CoV cases assessed at the adult tertiary-care hospital in Singapore between September 2012 and December 2015. In total, 262 patients (31%) were hospitalized. All had MERS-CoV infection ruled out by RT-PCR or clinical assessment. Two hundred and thirty (88%) of the hospitalized patients were also investigated for influenza virus by RT-PCR. Of these, 62 (27%) tested positive for seasonal influenza. None of the patients with positive influenza results had been vaccinated in the year prior to hospital admission. Ninety-three (36%) out of the 262 hospitalized patients had clinical and/or radiological evidence of pneumonia. This study demonstrates the potential benefits of pre-travel vaccination against influenza and pneumococcal disease.

Do men and women with intellectual disabilities understand death?

BACKGROUND: Individuals with ID are often withheld information about the death of their loved ones as it has often been thought that they do not understand death or cannot grieve. This grief exacerbates the stress of individuals with ID as they often encounter secondary losses such as transitioning to a care facility. The aim of this study is to investigate men and women with ID understanding death concepts and to what extent. METHOD: Adopting a stratified random sampling method, 156 Chinese people with ID were invited to join the study. One hundred and ten participants were interviewed using simple death related vignettes expanding upon and replicating a published study carried out in Ireland. The understanding of the five death concepts: causality, irreversibility, nonfunctionality, universality and inevitability was examined. The correlates of demographics, bereavement experiences and comprehension were explored. RESULTS: The majority of the participants did understand concepts such as death is irreversible and that the deceased no longer function. One third of the participants understood causality and the universality of death. One fifth understood the inevitability of death. Previous bereavement experiences were correlated with higher understanding. Communication and community skills were correlated with all concepts of death except universality. CONCLUSION: The results indicate that individuals with ID do have a partial to full understanding of the concepts of death. The culture of Hong Kong is one that considers death to be a taboo or unlucky subject. Therefore, the results mirror the the lack of understanding of universality and inevitability concepts as it is forbidden to speak of these concepts. An open and honest environment is encouraged to educate individuals with ID about death and bereavement.

Administrative data is as good as medical chart review for comorbidity ascertainment in patients with infections in Singapore.

The Charlson comorbidity index (CCI) is widely used for control of confounding from comorbidities in epidemiological studies. International Classification of Diseases (ICD)-coded diagnoses from administrative hospital databases is potentially an efficient way of deriving CCI. However, no studies have evaluated its validity in infectious disease research. We aim to compare CCI derived from administrative data and medical record review in predicting mortality in patients with infections. We conducted a cross-sectional study on 199 inpatients. Correlation analyses were used to compare comorbidity scores from ICD-coded administrative databases and medical record review. Multivariable regression models were constructed and compared for discriminatory power for 30-day in-hospital mortality. Overall agreement was fair [weighted kappa 0·33, 95% confidence interval (CI) 0·23-0·43]. Kappa coefficient ranged from 0·17 (95% CI 0·01-0·36) for myocardial infarction to 0·85 (95% CI 0·59-1·00) for connective tissue disease. Administrative data-derived CCI was predictive of CCI ⩾5 from medical record review, controlling for age, gender, resident status, ward class, clinical speciality, illness severity, and infection source (C = 0·773). Using the multivariable model comprising age, gender, resident status, ward class, clinical speciality, illness severity, and infection source to predict 30-day in-hospital mortality, administrative data-derived CCI (C = 0·729) provided a similar C statistic as medical record review (C = 0·717, P = 0·8548). In conclusion, administrative data-derived CCI can be used for assessing comorbidities and confounding control in infectious disease research.

Vancomycin-resistant enterococci with reduced daptomycin susceptibility in Singapore: prevalence and associated factors.

Prevalence of vancomycin-resistant enterococci (VRE) and use of daptomycin are increasing in Asia. To determine the prevalence of daptomycin non-susceptible enterococci (DNSE) and understand factors associated with reduced daptomycin susceptibility in VRE, we conducted a case-control study in a 1600-bed adult tertiary hospital in Singapore. All VRE isolates from inpatients in 2012 were tested for daptomycin susceptibility. Patients with VRE isolates of daptomycin minimum inhibitory concentration (MIC) ⩾3 µg/ml were classified as daptomycin-reduced susceptible VRE (DRS-VRE) and those with daptomycin MIC 4 µg/ml (DNSE). About half (135, 55%) had reduced susceptibility to daptomycin (MIC 3-4 µg/ml). None in the DS-VRE group had prior exposure to daptomycin. After adjusting for age, gender, comorbidity, hospitalization duration, surgical history, indwelling device use, and duration of antibiotic exposure in the prior 3 months, >1 movement between wards [odds ratio (OR) 0·35, 95% confidence interval (CI) 0·16-0·74, P = 0·006] and minocycline resistance (OR 0·45, 95% CI 0·25-0·84, P = 0·011) were independently associated with DRS-VRE. Our study suggests that daptomycin exposure, >1 movement between wards, and resistance to minocycline, were associated with reduced daptomycin susceptibility in VRE.

Length of stay an important mediator of hospital-acquired methicillin-resistant Staphylococcus aureus.

Hospital-acquired methicillin-resistant Staphylococcus aureus (HA-MRSA) is becoming increasingly established in Asian hospitals. The primary aim of this study was to decompose the risk factors for HA-MRSA based on conceptual clinical pathways. The secondary aim was to show the amount of effect attributable to antibiotic exposure and total length of stay before outcome (LBO) so that institutions can manage at-risk patients accordingly. A case-control study consisting of 1200 inpatients was conducted in a large tertiary hospital in Singapore between January and December 2006. Results from the generalized structural equation model (GSEM) show that LBO [adjusted odds ratio (aOR) 14·9, 95% confidence interval (CI) 8·7-25·5], prior hospitalization (aOR 6·2, 95% CI 3·3-11·5), and cumulative antibiotic exposure (aOR 3·5, 95% CI 2·3-5·3), directly affected HA-MRSA acquisition. LBO accounted for the majority of the effects due to age (100%), immunosuppression (67%), and surgery (96%), and to a lesser extent for male gender (22%). Our model enabled us to account and quantify effects of intermediaries. LBO was found to be an important mediator of age, immunosuppression and surgery on MRSA infection. Traditional regression approaches will not only give different conclusions but also underestimate the effects. Hospitals should minimize the hospital stay when possible to reduce the risk of MRSA.

Safety and efficacy of multipolar pulmonary vein ablation catheter vs. irrigated radiofrequency ablation for paroxysmal atrial fibrillation: a randomized multicentre trial.

AIMS: The current challenge in atrial fibrillation (AF) treatment is to develop effective, efficient, and safe ablation strategies. This randomized controlled trial assesses the medium-term efficacy of duty-cycled radiofrequency ablation via the circular pulmonary vein ablation catheter (PVAC) vs. conventional electro-anatomically guided wide-area circumferential ablation (WACA). METHODS AND RESULTS: One hundred and eighty-eight patients (mean age 62 ± 12 years, 116 M : 72 F) with paroxysmal AF were prospectively randomized to PVAC or WACA strategies and sequentially followed for 12 months. The primary endpoint was freedom from symptomatic or documented >30 s AF off medications for 7 days at 12 months post-procedure. One hundred and eighty-three patients completed 12 m follow-up. Ninety-four patients underwent PVAC PV isolation with 372 of 376 pulmonary veins (PVs) successfully isolated and all PVs isolated in 92 WACA patients. Three WACA and no PVAC patients developed tamponade. Fifty-six percent of WACA and 60% of PVAC patients were free of AF at 12 months post-procedure (P = ns) with a significant attrition rate from 77 to 78%, respectively, at 6 months. The mean procedure (140 ± 43 vs. 167 ± 42 min, P<0.0001), fluoroscopy (35 ± 16 vs. 42 ± 20 min, P<0.05) times were significantly shorter for PVAC than for WACA. Two patients developed strokes within 72 h of the procedure in the PVAC group, one possibly related directly to PVAC ablation in a high-risk patient and none in the WACA group (P = ns). Two of the 47 patients in the PVAC group who underwent repeat ablation had sub-clinical mild PV stenoses of 25-50% and 1 WACA patient developed delayed severe PV stenosis requiring venoplasty. CONCLUSION: The pulmonary vein ablation catheter is equivalent in efficacy to WACA with reduced procedural and fluoroscopy times. However, there is a risk of thrombo-embolic and pulmonary stenosis complications which needs to be addressed and prospectively monitored. CLINICALTRIALSGOV IDENTIFIER: NCT00678340.

Proximity to animal or crop operations may be associated with de novo daptomycin-non-susceptible Enterococcus infection.

Daptomycin-non-susceptible enterococci (DNSE) are emerging pathogens. We have previously reported de novo DNSE isolates in patients with agricultural activities and exposure to livestock. We studied the geographical distribution of the residencies of 34 patients with DNSE infections described in a tertiary centre over a 5-year period in an effort to explore the association between patients' residential locations and agricultural and farm lands. Nine patients had no prior exposure to daptomycin (de novo) and seven of these lived in areas with animal or crop operations. Of those living near an animal or crop operation, the mean number of operations in the proximity of the residence of patients with daptomycin-exposed DNSE was 13.8 (range 1-67) compared to 98.6 (3-529) for those patients with de novo DNSE (P = 0.0486). These data are consistent with previous reports that the transport of daptomycin resistance genes between animals and humans may be a possible mechanism for development of de novo daptomycin resistance in enterococci.

An education booklet to aid cardiac patients' recovery at home.

BACKGROUND: Hospital and home-based cardiac rehabilitation programmes improve the health outcomes of cardiac patients. Both types of programmes include patient education as a core component. However, many patients do not attend cardiac rehabilitation programmes for a variety of reasons. In Singapore, where cardiac rehabilitation is comparatively uncommon, patient education is usually delivered face-to-face by healthcare professionals because educational materials designed specifically for cardiac patients recovering at home are not available. AIM: This paper describes the development of a patient education booklet designed to aid recovery at home after a myocardial infarction in Singapore. METHODS: The conception and development of this evidence-based Heart Recovery Education Booklet was based on patient need and current clinical guidelines pertaining to cardiac rehabilitation and planned in consultation with specialists such as cardiologists, psychiatrists and physiotherapists. RESULTS: The booklet is a patient resource to aid recovery at home after an myocardial infarction. It is interactive, based on identified need and aims to guide and assist the patient in performing their usual activities of daily living and adhering to treatment regimens, including exercise. CONCLUSION: This booklet is a resource for patients with myocardial infarction and healthcare professionals and its effectiveness in improving health-related quality of life, psychological status and coronary risk profile is to be tested in a randomized controlled trial. IMPLICATIONS FOR NURSING AND HEALTH POLICY: Policy makers in health and nursing must find ways of developing and implementing cardiac rehabilitation programmes that aid recovery from myocardial infarction. This education booklet offers one way to do this.

Prevention of tea-induced extrinsic tooth stain.

OBJECTIVES: The objectives of this study were to determine whether the addition of milk to tea reduces the ability of tea to stain extracted human teeth and, if so, to ascertain the component of milk that is responsible for milk's stain reducing properties. METHODS: Extracted human teeth were immersed in a tea solution, with the addition of 2% milk, 5.26% lactose, 2.7% casein or 10% fat-free milk for 24 h at 37°C. A dental spectrophotometer (VITA Easyshade Compact) was used to evaluate the colour of the teeth both before and after immersion in the tea solutions. Commission internationale de l'éclairage (CIE) L*a*b* colour space values were recorded, and the change in colour (ΔE*) was calculated. A two-tailed t-test or one-way analysis of variance (anova) was used to determine whether there were statistical differences between groups. RESULTS: Milk significantly reduces the ability of tea to stain teeth (P = 0.0225), specifically in the L* and a* dimensions (P = 0.0182 and P = 0.0124, respectively) of the colour sphere. Casein, which makes up 80% of the protein content in bovine milk, is the component of milk that is responsible for significantly reducing tea's ability to stain teeth (P < 0.0001). CONCLUSIONS: The addition of milk to tea significantly reduces the tea's ability to stain teeth. Casein was determined to be the component of milk that is responsible for preventing tea-induced staining of teeth to a similar order of magnitude that can be obtained by vital bleaching treatments.

Octenidine exposure was not associated with reduced octenidine susceptibility of meticillin-resistant Staphylococcus aureus in an extended-care facility in Singapore.

OBJECTIVES: Antiseptics such as chlorhexidine gluconate (CHG) and octenidine dihydrochloride (OCT) are frequently used in hospitals to prevent and control the transmission of meticillin-resistant Staphylococcus aureus (MRSA). Given the increasing prevalence of reduced CHG susceptibility of MRSA, there are concerns about the possibility of reduced OCT susceptibility. This study evaluated the prevalence of reduced CHG and OCT susceptibility over 3 years, and assessed the association between OCT exposure and reduced OCT susceptibility in MRSA. METHODS: MRSA isolates from inpatients who acquired MRSA in an extended-care facility between 2019 and 2021 were included in antiseptic susceptibility testing. Inpatients were exposed to universal daily CHG bathing from January to September 2019, and universal daily OCT bathing after October 2019. The minimum inhibitory concentrations (MICs) of CHG and OCT were determined using the broth microdilution method. Multi-variable logistic regression was used to assess if OCT exposure was independently associated with reduced OCT susceptibility. RESULTS: Of 186 isolates, 179 (96%) had reduced CHG susceptibility (MIC ≥4 mg/L) and 46 (25%) had reduced OCT susceptibility (MIC ≥2 mg/L). Reduced OCT susceptibility rates were 26.9%, 13.8% and 14.3% in 2019, 2020 and 2021, respectively. Reduced CHG susceptibility rates were 95.4%, 100% and 95.9% in 2019, 2020 and 2021, respectively. OCT exposure was not associated with reduced OCT susceptibility (adjusted odds ratio 0.23, 95% confidence interval 0.08-0.75; P=0.014), after adjusting for age, gender, race, year of sample collection, days at risk in facility, hospitalization in preceding year, and MRSA colonization/infection in preceding year. CONCLUSION: The prevalence of reduced OCT susceptibility has remained low, despite universal OCT bathing for extended inpatient care. However, the rate of reduced CHG susceptibility was high. OCT exposure was not associated with reduced OCT susceptibility in MRSA.