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.

Socioecological differences in factors associated with inconsistent condom use with female sex workers and casual partners: an observational study of heterosexual men attending an anonymous HIV testing clinic in Singapore.

Sexual practices among heterosexual men may differ between female sex workers (FSWs) and casual partners. We surveyed 203 heterosexual men and investigated the attributes associated with inconsistent condom use among them. Lower educational attainment was positively associated with inconsistent condom use with FSWs (adjusted prevalence ratio (aPR) 2.63; P = 0.018) and casual partners (aPR 1.55; P = 0.022), whereas early age of sexual debut (aPR 3.00; P = 0.012) and alcohol use during sex (aPR 7.95; P < 0.001) were positively associated with inconsistent condom use with FSWs. Socioecological factors may explain such differences.

Contacts of healthcare workers, patients and visitors in general wards in Singapore.

To characterize contacts in general wards, a prospective survey of healthcare workers (HCWs), patients and visitors was conducted using self-reported diary, direct observation and telephone interviews. Nurses, doctors and assorted HCWs reported a median of 14, 18 and 15 contact persons over one work shift, respectively. Within 1 h, we observed 3·5 episodes with 25·6 min of cumulative contact time for nurses, 2·9 episodes and 22·1 min for doctors and 5·0 episodes with 44·3 min for assorted-HCWs. In interactions with patients, nurses had multiple brief episodes of contact; doctors had fewer episodes and less cumulative contact time; assorted-HCWs had fewer contact episodes of longer durations (than for nurses and doctors). Assortative mixing occurred amongst HCWs: those of the same HCW type were the next most frequent class of contact after patients. Over 24-h, patients contacted 14 persons with 23 episodes and 314·5 min of contact time. Patient-to-patient contact episodes were rare, but a maximum of five were documented from one patient participant. 22·9% of visitors reported contact with patients other than the one they visited. Our study revealed differences in the characteristics of contacts among different HCW types and potential transmission routes from patients to others within the ward environment.

Strengthening teachers' abilities to implement a vision health program in Taiwanese schools.

We designed a school-based, nationwide program called the 'New Era in Eye Health' to strengthen teacher training and to examine whether the existence of a government vision care policy influenced teachers' vision care knowledge and students' behavior. Baseline data and 3-month follow-up data were compared. A random sample of teachers (n = 660) from school vision health clusters in 22 cities/counties in Taiwan were invited to participate in our study and 436 agreed to participate (response rate = 66.1%). The mean age of participant teachers was 41.2 years, while the length of service mean was 14.6 years. For monitoring teacher outcomes, five cities/counties were selected as the intensely monitored group based on certain criteria. Sunlight diaries (n = 5434) were distributed and 3342 (61.5%) were returned. Teachers showed significant improvements in knowledge and behavior on the school vision health questionnaire. At the 3-month follow-up, the number of recesses as recorded by students' 'sunlight diary' increased. When teachers had better knowledge and behavior, recesses also increased. This study provided valuable insights to guide dissemination efforts for school vision health interventions and to help teachers implement research into their school vision health activities.

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.

Performance of case definitions for influenza surveillance.

Influenza-like illness (ILI) case definitions, such as those from the European Centre for Disease Control and Prevention, World Health Organization (WHO) and United States Centers for Disease Control and Prevention, are commonly used for influenza surveillance. We assessed how various case definitions performed during the initial wave of influenza A(H1N1) pdm09 infections in Singapore on a cohort of 727 patients with two to three blood samples and whose symptoms were reviewed fortnightly from June to October 2009. Using seroconversion (≥ 4-fold rise) to A/California/7/2009 (H1N1), we identified 36 presumptive influenza A(H1N1)pdm09 episodes and 664 episodes unrelated to influenza A(H1N1)pdm09. Cough, fever and headache occurred more commonly in presumptive influenza A(H1N1)pdm09. Although the sensitivity was low (36%), the recently revised WHO ILI case definition gave a higher positive predictive value (42%) and positive likelihood ratio (13.3) than the other case definitions. Results including only episodes with primary care consultations were similar. Individuals who worked or had episodes with fever, cough or sore throat were more likely to consult a physician, while episodes with Saturday onset were less likely, with some consultations skipped or postponed. Our analysis supports the use of the revised WHO ILI case definition, which includes only cough in the presence of fever defined as body temperature ≥ 38 °C for influenza surveillance.

Influenza and the pandemic threat.

With the increasing concern of an imminent influenza pandemic, Singapore and many other countries have been developing preparedness plans. Influenza affects an estimated 20 percent of the population of Singapore annually, and local outbreaks can last for more than 12 weeks and occur at different periods of the year. The 1968 pandemic in Singapore had a clinical attack rate of about 20 percent and resulted in infections with fever that lasted up to five days. However, absenteeism from work due to seasonal influenza-like illnesses was estimated to be less than one day per person in Singapore. The next pandemic in Singapore is predicted to cause an average of 1,105 deaths and 3,338 hospitalisations, while a severe pandemic will cause more healthcare damage. Preventive strategies include national public health initiatives, vaccination, anti-viral therapy, and hygiene measures. To develop effective preparedness plans, it is important for healthcare workers to understand the disease's epidemiology, outcomes, and treatment and prevention strategies available.

Surveillance of severe acute respiratory syndrome (SARS) in the post-outbreak period.

INTRODUCTION: This retrospective one-month survey evaluated the practicality of post-severe acute respiratory syndrome (SARS) surveillance recommendations in previously SARS-affected countries, namely Singapore. These included staff medical sick leave for febrile illness, inpatient fevers, inpatient pneumonia, atypical pneumonia, febrile illnesses with significant travel history and sudden unexplained deaths from pneumonia/ adult respiratory distress syndrome (ARDS). METHODS: Surveillance data on medical sick leave of staff, all inpatient fevers, all febrile (temperature greater than or equal to 38 degrees Celsius) inpatient pneumonia, including atypical pneumonia, and deaths from pneumonia were collected from sick leave reports, ward reports, isolation room rounds and mortuary reports from 1 to 28 September 2003. RESULTS: Baseline results show 167 (1.4/1000 staff-days) observed in staff sick leave for febrile illnesses, and 1798 (71.3/1000 bed-days) observed for inpatient fever. There were 40, 31 and 12 instances, respectively, of staff having temperatures of high fever (greater than or equal to 38 degrees Celsius), prolonged sick leave (3 days or more), and repeated sick leave (within 7 days) for febrile illnesses. An average of 4.6 wards a day potentially fulfilled the World Health Organisation SARS alert criteria. Of 27 cases with fever, pneumonia and a total white count of less than 10,000 cells per cubic mm as per Ministry of Health, Singapore criteria for the diagnosis of atypical pneumonia, only five were identified by clinicians. CONCLUSION: Surveillance is time-consuming and current recommendations are not specific enough to be used practically. Surveillance indicators for inpatients must overcome a high degree of background noise.

An assessment of electronically captured data in the patient care enhancement system (PACES) for syndromic surveillance.

INTRODUCTION: A common approach to the surveillance of emerging infectious diseases and agents of bioterrorism is to analyse electronically captured data for disease syndromes. The Patient Care Enhancement System (PACES) is a form of electronic medical records presently in service in the Singapore Armed Forces (SAF). We assess the feasibility of PACES data for surveillance, describe time-trends, and identify methods of sub-analysis which could improve performance. MATERIALS AND METHODS: Medical consults from July 2000 to June 2003 were extracted. Diagnosis codes were mapped to 7 infectious disease syndromes according to the categorisation in the Electronic Surveillance System for the Early Notification of Community-based Epidemics (ESSENCE): gastrointestinal (GI), fever (FEVER), respiratory, (RESP), coma (COMA), neurological (NEURO), dermatologic-haemorrhagic (DERMHEM) and dermatologic- infectious (DERM-INF). RESULTS: A total of 732,233 episodes of care were analysed. Weekly periodicity was observed, with decreased weekend consults; there were no obvious seasonal trends in any of the syndromes. RESP, FEVER and GI syndromes were common events. Sub-analyses, either by restricting to cases with a repeated consultation, or grouping the data by medical centres, could dramatically lower thresholds used to flag outbreaks. CONCLUSION: In spite of the level of background noise inherent in a system consisting mainly of primary care consults, sub-analysis by medical centre, or restriction to cases with repeated consults were able to yield sensitive thresholds for outbreak detection.

1995 Volvo Award in basic sciences. The use of an osteoinductive growth factor for lumbar spinal fusion. Part I: Biology of spinal fusion.

STUDY DESIGN: The histology of lumbar intertransverse process spinal fusion was studied in an experimental model in rabbits. OBJECTIVES: To qualitatively and quantitatively analyze the sequential histology of spinal fusion using a previously validated animal model. SUMMARY OF BACKGROUND DATA: Few previous studies have described the sequential histology during the posterolateral spinal fusion healing process using autogenous bone, and a basic understanding of the biology of this repair process is lacking. METHODS: Fourteen adult New Zealand white rabbits underwent single-level posterolateral lumbar intertransverse process arthrodesis with autogenous iliac bone graft. Animals were killed 1-10 weeks after surgery, and the fusion masses were analyzed histologically and quantitated using a semiautomated image analysis system. RESULTS: Three distinct phases of healing were identified (inflammatory, reparative, and remodeling) and occurred in sequence but in a delayed fashion in the central zone of the fusion mass compared with the outer transverse process zones. Membraneous bone formation, evident first at the ends of the fusion eminating from the decorticated transverse processes, was the predominant mechanism of healing. The central zone was somewhat different in that there was a period of endochondral bone formation during weeks 3 and 4 in this zone where cartilage formed and was converted to bone. Remodeling in the central zone had equilibrated with the transverse process zones by 10 weeks. CONCLUSIONS: Lumbar intertransverse process spinal fusion is a complex process from a spatial and temporal standpoint. When autogenous bone is used as the graft material, this process critically depends on a variety of factors from the decorticated host bone and exposed marrow. The persistence of a central cartilage zone may be related to some types of nonunions and deserves future investigation. This enhanced understanding of the biology of spinal fusion with autogenous bone graft will provide a foundation for optimizing the use of osteoinductive bone growth factors in this healing process.

Epidemiological, clinical and laboratory characteristics of 19 serologically confirmed rickettsial disease in Singapore.

AIM: To identify epidemiological, clinical and laboratory features of serologically-proven typhus in the local setting. METHOD & RESULTS: Retrospective study looking at rickettsial serologies done over a six-month period and collection of the epidemological, clinical, laboratory and treatment response data from the case notes of the patients with an ordered rickettsial serology. Twenty of the 35 cases had a positive serology. Of these 20 patients, 18 were already clinically diagnosed as having murine typhus. All except one were males and all were migrant workers. Majority of the patients were construction workers staying in containers where rats abound. The most consistent clinical features were high fever (100%) for a median period of seven days, headache (94%) and cough (47%). The white cell count was usually normal (74%) but thrombocytopenia was common (68%). Transaminitis was also common (90%) with the AST component higher than the ALT in half of the cases. Response to doxycycline therapy was rapid and most (88%) were afebrile by 72 hours. CONCLUSION: Typhus (notably murine type) can be confidently diagnosed from consistent clinical features supported by epidemiological and laboratory clues. Early recognition with the prompt treatment response will result in shorter hospital stay with decreased cost. Serological testing may only prove useful in difficult situations when the clinical diagnosis is less clear.

Hyperlipidaemia during normal pregnancy, parturition and lactation.

Excessive accumulation of one or more of the major lipids in plasma can produce a marked increase in the risk of coronary heart diseases and other vascular complications. During and after pregnancy, changes in the levels of total cholesterol, triglyceride, low density lipoprotein-cholesterol, and high density lipoprotein-cholesterol have been described, but the amount of change varies from study to study. Therefore, the present study investigated changes in lipids and lipoproteins throughout the pregnancy and puerperium. We also investigated for the factors which may affect the plasma lipids during pregnancy. Concentrations of cholesterol and triglyceride of total plasma and lipoproteins were determined in 42 pregnant women throughout their pregnancy and puerperium together with a control group of 42 non-pregnant women. Compared to the control group, concentrations of cholesterol and triglyceride of total plasma and lipoproteins increased significantly during the second trimester and reached maximum in the third trimester. Concentrations of both, cholesterol and triglyceride, decreased significantly during post-partum. There was, however, a strikingly more rapid fall of plasma triglyceride and cholesterol in those mothers who breast-fed their infants compared with that in those in whom lactation was never established. In the majority of subjects, cholesterol and triglycerides remained significantly high until the fourth week of post-partum. The magnitude of the plasma cholesterol increment appeared in part to be related to that of plasma triglycerides, but these increments appeared to be independent of age, weight gain, numbers of previous pregnancies and sex of the foetus. This study concludes that hyperlipidaemia is a common finding during pregnancy and during post-partum. The concentrations of both cholesterol and triglycerides remain significantly higher in bottle-feeding than in breast-feeding mothers.

Flexor tendon suture methods: a quantitative analysis of suture material within the repair site.

This study compared the cross-sectional area and volume occupied by suture material at the repair site in three common methods of flexor tendon repair. A total of 51 human cadaveric tendons were studied. Zone II flexor digitorum profundus tendon lacerations were created and then repaired using the techniques described by Kessler, Tajima, and Savage. Quantitative cross-sectional area and volumetric measurements of suture material within each repair site were determined using a digital image analysis system. The Tajima repair occupied 27% of the tendon area at the repair site, while the Savage and Kessler repairs occupied 18% and 2%, respectively.

New influenza A (H1N1) 2009 in Singapore: the first ten adult imported cases.

INTRODUCTION: Since late March 2009, a novel influenza H1N1 strain emerged in humans in Mexico and the United States. It has rapidly spread to many countries on different continents, prompting unprecedented activation of pandemic preparedness plans. Singapore has adopted a containment strategy with active screening of febrile travellers with respiratory symptoms from affected countries since April 27, 2009. METHODS: All cases with new influenza A (H1N1) confirmed on polymerase chain reaction assay on combined nasal and throat swabs and who were admitted to the Communicable Disease Centre, were included in a prospective evaluation of clinical characteristics of new influenza A (H1N1). RESULTS: From May 26 to June 3, 2009, there were ten patients with a mean age of 27.6 years, seven of whom were female. All but one travelled from the United States, six of whom travelled from New York; the last one travelled from the Philippines. Clinical illness developed within a mean of 1.4 days after arrival in Singapore, and presentation to the emergency department at a mean of 2.7 days from illness onset. Fever occurred in 90 percent, cough 70 percent, coryza 40 percent, sore throat and myalgia/arthralgia 30 percent; none had diarrhoea. The fever lasted a mean of 2.1 days. All were treated with oseltamivir. The clinical course was uncomplicated in all cases. CONCLUSION: Clinical features of new influenza A (H1N1) appeared mild, and ran an uncomplicated course in immunocompetent patients.

Is it important to secure the horns during lateral meniscal transplantation? A cadaveric study.

The purpose of this investigation was to determine if secure attachment of the horns of the lateral meniscus during transplantation affects the load-bearing function of the meniscus. Six knee joints were loaded in compression (310 N) and the interarticular contact pressure in the joint measured using pressure-sensitive film inserted into the joint. Each knee was tested first with the original intact meniscus and then after each of the following surgical procedures involving the original lateral meniscus: (1) total meniscectomy; (2) meniscal transplantation with a tibial bone bridge; (3) meniscal transplantation with neither horn secured; (4) meniscal transplantation with the anterior horn secured; (5) meniscal transplantation with the posterior horn secured; and (6) meniscal transplantation with both horns secured. The results are as follows. (1) The intact joint gave the largest contact area and the smallest peak contact pressure. The joint with the total meniscectomy gave the smallest contact area and the largest peak contact pressure. (2) A meniscal transplantation with either a tibial bony bridge or with both horns secured gave results similar to those for the intact joint. (3) A meniscal transplantation with only one horn secured gave results somewhere in between those for the intact joint and those for the joint without a meniscus. A meniscal transplantation with neither horn secured gave results similar to those for a joint without a meniscus.