First nosocomial cluster of COVID-19 due to the Delta variant in a major acute care hospital in Singapore: investigations and outbreak response.

OBJECTIVES: The first large nosocomial cluster of coronavirus disease 2019 (COVID-19) in Singapore in April 2021 led to partial closure of a major acute care hospital. This study examined factors associated with infection among patients, staff and visitors; investigated the possible role of aerosol-based transmission; evaluated the effectiveness of BNT162.b2 and mRNA1273 vaccines; and described the successful containment of the cluster. METHODS: Close contacts of patients with COVID-19 and the affected ward were identified and underwent surveillance for severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection. Patient, staff and visitor cohorts were constructed and factors associated with infection were evaluated. Phylogenetic analysis of patient samples was performed. Ward air exhaust filters were tested for SARS-CoV-2. RESULTS: In total, there were 47 cases, comprising 29 patients, nine staff, six visitors and three household contacts. All infections were of the Delta variant. Ventilation studies showed turbulent air flow and swabs from air exhaust filters were positive for SARS-CoV-2. Vaccine breakthrough infections were seen in both patients and staff. Among patients, vaccination was associated with a 79% lower odds of infection with COVID-19 (adjusted odds ratio 0.21, 95% confidence interval 0.05-0.95). CONCLUSIONS: This cluster occurred despite enhancement of infection control measures that the hospital had undertaken at the onset of the COVID-19 pandemic. It was brought under control rapidly through case isolation, extensive contact tracing and quarantine measures, and led to enhanced use of hospital personal protective equipment, introduction of routine rostered testing of inpatients and staff, and changes in hospital infrastructure to improve ventilation within general wards.

Neuroimaging in Zoonotic Outbreaks Affecting the Central Nervous System: Are We Fighting the Last War?

When preparing for the coronavirus disease 2019 pandemic and its effects on the CNS, radiologists should be familiar with neuroimaging appearances in past zoonotic infectious disease outbreaks. Organisms that have crossed the species barrier from animals to humans include viruses such as Hendra, Nipah, Severe Acute Respiratory Syndrome, and influenza, as well as bacteria and others. Brain CT and MR imaging findings have included cortical abnormalities, microinfarction in the white matter, large-vessel occlusion, and features of meningitis. In particular, the high sensitivity of diffusion-weighted MR imaging in detecting intracranial abnormalities has been helpful in outbreaks. Although the coronaviruses causing the previous Severe Acute Respiratory Syndrome outbreak and the current coronavirus disease 19 pandemic are related, it is important to be aware of their similarities as well as potential differences. This review describes the neuroimaging appearances of selected zoonotic outbreaks so that neuroradiologists can better understand the current pandemic and potential future outbreaks.

Effects of short-term step aerobics exercise on bone metabolism and functional fitness in postmenopausal women with low bone mass.

Measurement of bone turnover markers is an alternative way to determine the effects of exercise on bone health. A 10-week group-based step aerobics exercise significantly improved functional fitness in postmenopausal women with low bone mass, and showed a positive trend in reducing resorption activity via bone turnover markers. INTRODUCTION: The major goal of this study was to determine the effects of short-term group-based step aerobics (GBSA) exercise on the bone metabolism, bone mineral density (BMD), and functional fitness of postmenopausal women (PMW) with low bone mass. METHODS: Forty-eight PMW (aged 58.2 ± 3.5 years) with low bone mass (lumbar spine BMD T-score of -2.00 ± 0.67) were recruited and randomly assigned to an exercise group (EG) or to a control group (CG). Participants from the EG attended a progressive 10-week GBSA exercise at an intensity of 75-85 % of heart rate reserve, 90 min per session, and three sessions per week. Serum bone metabolic markers (C-terminal telopeptide of type 1 collagen [CTX] and osteocalcin), BMD, and functional fitness components were measured before and after the training program. Mixed-models repeated measures method was used to compare differences between the groups (α = 0.05). RESULTS: After the 10-week intervention period, there was no significant exercise program by time interaction for CTX; however, the percent change for CTX was significantly different between the groups (EG = -13.1 ± 24.4 % vs. CG = 11.0 ± 51.5 %, P < 0.05). While there was no significant change of osteocalcin in both groups. As expected, there was no significant change of BMD in both groups. In addition, the functional fitness components in the EG were significantly improved, as demonstrated by substantial enhancement in both lower- and upper-limb muscular strength and cardiovascular endurance (P < 0.05). CONCLUSION: The current short-term GBSA exercise benefited to bone metabolism and general health by significantly reduced bone resorption activity and improved functional fitness in PMW with low bone mass. This suggested GBSA could be adopted as a form of group-based exercise for senior community.

Implementation hurdles of an interactive, integrated, point-of-care computerised decision support system for hospital antibiotic prescription.

Antimicrobial stewardship is used to combat antimicrobial resistance. In Singapore, a tertiary hospital has integrated a computerised decision support system, called Antibiotic Resistance Utilisation and Surveillance-Control (ARUSC), into the electronic inpatient prescribing system. ARUSC is launched either by the physician to seek guidance for an infectious disease condition or via auto-trigger when restricted antibiotics are prescribed. This paper describes the implementation of ARUSC over three phases from 1 May 2011 to 30 April 2013, compared factors between ARUSC launches via auto-trigger and for guidance, examined factors associated with acceptance of ARUSC recommendations, and assessed user acceptability. During the study period, a monthly average of 9072 antibiotic prescriptions was made, of which 2370 (26.1%) involved ARUSC launches. Launches via auto-trigger comprised 48.1% of ARUSC launches. In phase 1, 23% of ARUSC launches were completed. This rose to 38% in phase 2, then 87% in phase 3, as escapes from the ARUSC programme were sequentially disabled. Amongst completed launches for guidance, 89% of ARUSC recommendations were accepted versus 40% amongst completed launches via auto-trigger. Amongst ARUSC launches for guidance, being from a medical department [adjusted odds ratio (aOR)=1.20, 95% confidence interval (CI) 1.04-1.37] and ARUSC launch during on-call (aOR=1.81, 95% CI 1.61-2.05) were independently associated with acceptance of ARUSC recommendations. Junior physicians found ARUSC useful. Senior physicians found ARUSC reliable but admitted to having preferences for antibiotics that may conflict with ARUSC. Hospital-wide implementation of ARUSC encountered hurdles from physicians. With modifications, the completion rate improved.

Debate on MERS-CoV respiratory precautions: surgical mask or N95 respirators?

Since the emergence of Middle East respiratory syndrome coronavirus (MERS-CoV) in mid-2012, there has been controversy over the respiratory precaution recommendations in different guidelines from various international bodies. Our understanding of MERS-CoV is still evolving. Current recommendations on infection control practices are heavily influenced by the lessons learnt from severe acute respiratory syndrome. A debate on respiratory precautions for MERS-CoV was organised by Infection Control Association (Singapore) and the Society of Infectious Disease (Singapore). We herein discuss and present the evidence for surgical masks for the protection of healthcare workers from MERS-CoV.

Hand hygiene and infection control survey pre- and peri-H1N1-2009 pandemic: knowledge and perceptions of final year medical students in Singapore.

INTRODUCTION: Infection control and hand hygiene are taught at different points in the undergraduate medical curriculum. We conducted a survey on fifth year medical (M5) students pre- and peri-influenza A (H1N1-2009) pandemic, attempting to ascertain whether the pandemic had affected their knowledge, perception and practice of hand hygiene and other aspects of infection control. METHODS: A self-administered anonymous survey of M5 students was performed between August 2008 and February 2010, corresponding to two successive classes: M5-2008 (Class of 2004/09) and M5-2009 (Class of 2005/10). Completed survey forms were collated and analysed centrally. RESULTS: There were 191 and 123 respondents for M5-2008 and M5-2009, respectively, corresponding to 74.9% and 47.3% of the respective classes. More M5-2009 respondents recognised alcohol hand rub as the preferred mode of hand hygiene practice and felt that there were insufficient isolation facilities in hospitals. Otherwise, survey responses were consistent. The majority felt that few doctors practiced hand hygiene appropriately, with the major obstructing factor being lack of time during ward rounds. The most important factor for improving hand hygiene compliance among junior doctors and students was for senior clinicians to lead by example. A significant minority believed that it was necessary to isolate patients with chikungunya, malaria or HIV. CONCLUSION: The 2009 H1N1 pandemic made little impact on medical students' knowledge and practice of infection control. Nonetheless, their responses have suggested avenues for improving infection control practice, including persuading senior clinicians to lead by example in hand hygiene practice and addressing gaps in knowledge on patient isolation policies.

Eikenella corrodens discitis after spinal surgery: case report and literature review.

Eikenella corrodens is part of the normal flora of the mouth and upper respiratory tract and is usually associated with dental and head and neck infections. We report a case of Eikenella discitis occurring soon after spinal surgery in an otherwise healthy patient, review the literature on bone and joint infections unrelated to human bites and fist-fight injuries, and stress the importance of definitive diagnosis in post-operative spinal infections.

Clinics in diagnostic imaging (57). Melioidotic prostatic abscess.

A 46-year-old previously healthy man presented with urosepsis and lower urinary tract obstruction. Both urine and blood cultures grew Burkholderia pseudomallei. Intravenous Ceftazidime failed to control the infection. Prostatic abscess formation was first detected by transrectal ultrasonography, and the extent was subsequently delineated by computed tomography. The abscess was drained by transurethral resection, which served to eradicate a possible persistent focus of infection. The diagnosis and management of prostatic abscess, and Melioidosis infection, are discussed.

Bugs for the next century: the issue of antibiotic resistance.

OBJECTIVE: To address the issue of emerging antibiotic resistance and examine which organisms will continue to pose problems in the new century. METHODS: Review of articles pertaining to bacteria recognised for increasing resistance. RESULTS: Changing resistance patterns are correlated with patterns of antibiotic use. This results in fewer effective drugs against "old" established bacteria e.g. gram-positives such as Streptococcus pneumoniae and Staphylococcus aureus. Resistance in gram-negative bacteria is also steadily increasing. Nosocomial gram-negative bacteria are capable of many different resistance mechanisms, often rendering them multiply-resistant. Antibiotic resistance results in morbidity and mortality from treatment failures and increased health care costs. CONCLUSION: Despite extensive research and enormous resources spent, the pace of drug development has not kept up with the development of resistance. As resistance spreads, involving more and more organisms, there is concern that we may be nearing the end of the antimicrobial era. Measures that can and should be taken to counter this threat of antimicrobial resistance include co-ordinated surveillance, rational antibiotic usage, better compliance with infection control and greater use of vaccines.

Melioidosis splenic abscess--an unusual presentation as osteomyelitis of rib.

INTRODUCTION: We report an unusual case of splenic melioidosis abscess presenting as osteomyelitis. CLINICAL PICTURE: A 74-year-old nondiabetic gentleman presents with a non-healing left chest wall abscess from osteomyelitis. TREATMENT: He underwent rib resection and the infection was found to involve the underlying pleura, lung, adjacent stomach, liver and diaphragm with a splenic abscess. Splenectomy was performed. Histology showed suppurative granulomas and cultures grew Burkholderia pseudomallei. OUTCOME: The patient recovered well with antibiotics. CONCLUSION: Melioidosis should not be forgotten as a cause of chronic suppurative infections in our endemic population.

Nipah viral encephalitis or Japanese encephalitis? MR findings in a new zoonotic disease.

BACKGROUND AND PURPOSE: An epidemic of suspected Japanese encephalitis occurred in Malaysia in 1998-1999 among pig farmers. In neighboring Singapore, an outbreak occurred among pig slaughterhouse workers. It was subsequently established that the causative agent in the outbreak was not the Japanese encephalitis virus but a previously unknown Hendra-like paramyxovirus named Nipah virus. METHODS: The brain MR images of eight patients with Nipah virus infection were reviewed. All patients tested negative for acute Japanese encephalitis virus. Seven patients had contrast-enhanced studies and six had diffusion-weighted examinations. RESULTS: All patients had multiple small bilateral foci of T2 prolongation within the subcortical and deep white matter. The periventricular region and corpus callosum were also involved. In addition to white matter disease, five patients had cortical lesions, three had brain stem involvement, and a single thalamic lesion was detected in one patient. All lesions were less than 1 cm in maximum diameter. In five patients, diffusion-weighted images showed increased signal. Four patients had leptomeningeal enhancement and four had enhancement of parenchymal lesions. CONCLUSION: The brain MR findings in patients infected with the newly discovered Nipah paramyxovirus are different from those of patients with Japanese encephalitis. In a zoonotic epidemic, this striking difference in the appearance and distribution of lesions is useful in differentiating these diseases. Diffusion-weighted imaging was advantageous in increasing lesion conspicuity.

Clinical characteristics and natural history of human immunodeficiency virus infected patients seen at a general hospital in Singapore.

The number of patients with human immunodeficiency virus (HIV) infection in Singapore has risen over the years. A considerable proportion of them present with acquired immunodeficiency syndrome (AIDS). In this study, we document the clinical characteristics and natural history of a consecutive series of 50 patients who were found to have HIV infection when they were seen at a tertiary care hospital. The majority were in the 30 to 49 age group and the most common mode of acquisition was heterosexual contact. The patients presented with a variety of symptoms to 11 different clinical departments. Fifty-eight per cent of the patients had AIDS-defining illnesses at presentation, with Pneumocystis carinii pneumonia being the most common. On follow-up, the most frequently occurring opportunistic infection that developed was Cytomegalovirus retinitis. Most patients had multiple subsequent admissions--for both AIDS-defining and non AIDS-defining conditions. The median CD4 count of the cohort at presentation was 72/mm3. The median survival was 399 and 822 days in those who had and those who did not have an AIDS-defining illness at presentation, respectively. Mortality was most commonly attributed to pneumonia. HIV infection has protean manifestations and patients may present to various specialty departments; hence, doctors need to be aware of the spectrum of disease in order to make a diagnosis.

Bronchoscopy in immunocompromised host with pulmonary infiltrates.

Pulmonary complications related to immunosuppression may be secondary to infection, neoplasia, toxic effects of chemotherapy and radiotherapy or the primary disease itself. The diagnostic yield from bronchoscopic studies on immunocompromised hosts (ICH) with pulmonary infiltrates varies widely and the indication and timing for bronchoscopic procedures remain uncertain. We prospectively studied 60 consecutive ICH with pulmonary lesions over a 12-month period. Bronchoscopic studies were performed as soon as pulmonary lesions were detected and within 72 hours of antimicrobial treatment. The patients were divided into two groups: E (40 patients) and L (20 patients) were bronchoscoped on average 1.6 days (SD 0.8) and 16.7 days (SD 10.8) respectively after clinical detection and antimicrobial treatment. A total of 131 bronchoscopic procedures were performed. These included bronchoalveolar lavage 60, bronchoscopic lung biopsy 47, bronchial biopsy 8, brushing 8 and washing 8. Diagnostic yields for bronchoscopically obtained fluid and tissue histology were 45% and 49% respectively. Both complement each other resulting in a higher diagnostic yield of about 70% of the patients in both groups. Procedural complications were minor (13% of cases) and mortality was zero. Infections accounted for approximately two-thirds of the pulmonary lesions. Patients bronchoscoped earlier received less antimicrobial empiric therapy and had shorter hospitalisation. Despite delayed bronchoscopy in ICH in the late group, bronchoscopic results influenced in 85% of patients. However, based on earlier use of appropriate therapy, shorter hospitalisation and decreased costs, we recommend early bronchoscopy when response to empiric treatment has been unsatisfactory.

Urinary tract infections.

Urinary tract infections are common clinical problems which result in significant morbidity and even mortality. UTI's can range from minimal disease to life-threatening sepsis and it is important to differentiate between the former which usually involves the lower urinary tract and the latter which invariably involves the upper urinary tract. Diagnosis depends on an abnormal urine microscopy and demonstration of bacteria in the urine. Pre-therapy urine cultures are not mandatory in young women with uncomplicated UTI and many studies support the efficacy of short-course therapy in this groups of patients. For other patients, microbiological and radiological investigations are required and there is insufficient data to support short course therapy in these patients. Treatment guidelines are different in special situations such as prostatitis, pregnancy, catheter-related infection and recurrent infections.

Candidemia from a urinary tract source: microbiological aspects and clinical significance.

Twenty-six cases of candidemia associated with a well-defined urinary tract source were retrospectively identified and reviewed. Urinary tract abnormalities were present in 23 of 26 patients (88%), 19 (73%) of whom had urinary tract obstruction. Nineteen patients had undergone urinary tract procedures before the onset of candidemia. Episodes of candidemia were brief and low-grade in intensity (median duration, 1 day; median colony count, 1.5 cfu/10 mL of blood). Only eight patients (31%) received > or = 500 mg of amphotericin B. There were five in-hospital deaths (19%); two of these deaths were attributed to candidiasis. No late complications of candidemia were documented for the surviving patients. Patients with urologic pathology and candiduria who undergo surgery or manipulation of the urinary tract are at significant risk for candidemia, and further studies should examine the issue of administration of prophylaxis to this group.

The prevalence of invasive candidiasis in patients with extensive burns.

A retrospective study of patients admitted to the Singapore General Hospital Burn Unit with > 30% total body surface area burns was performed to establish the prevalence of fungal colonisation and invasive fungal disease (IFD). Forty-eight percent of patients surviving at least ten days following thermal injury had fungi isolated. IFD was documented in ten patients. Risk factors associated with the development of IFD, clues to assist in diagnosing IFD, and therapeutic options for managing IFD are reviewed.

Pulmonary alveolar proteinosis--a case report.

Pulmonary alveolar proteinosis is a relatively rare disease. Its etiology is unknown but it has been found associated with various opportunistic infections as well as immunological conditions. The clinical and radiological features may be indistinguishable from other respiratory disorders and diagnosis is often dependent on histology. Its course can vary from progressive deterioration to spontaneous improvement and treatment with bronchopulmonary lavage may not always be necessary. Many theories regarding pathogenesis have been put forward and most of these centre upon the roles of alveolar macrophages. We describe a case of Pulmonary Alveolar Proteinosis in a local Oriental male and reviewed the current understanding of its pathogenesis.