Limin Wijaya

Efficacy and safety of celgosivir in patients with dengue fever (CELADEN): a phase 1b, randomised, double-blind, placebo-controlled, proof-of-concept trial

BACKGROUND Dengue infection is the most common mosquito-borne viral disease worldwide, but no suitable antiviral drugs are available. We tested the α-glucosidase inhibitor celgosivir as a treatment for acute dengue fever. METHODS To establish eligibility for inclusion in a phase 1b, randomised, double-blind, placebo-controlled, proof-of-concept trial, individuals aged 21-65 years who had had a fever (≥38°C) for less than 48 h, met at least two criteria indicating probable dengue infection, and had a positive result on a dengue point-of-care test kit or PCR assay were referred for screening at a centre in Singapore between July 30, 2012, and March 4, 2013. Using a web-based system, we randomly assigned patients who met full inclusion criteria after screening (1:1; random permuted block length four) to celgosivir (initial 400 mg loading dose within 6 h of randomisation, followed by 200 mg every 12 h for a total of nine doses) or matched placebo. Patients and the entire study team were masked to group assignment. The primary endpoints were mean virological log reduction (VLR) from baseline for days 2, 3, and 4, and area under the fever curve (AUC) for a temperature above 37°C from 0 h to 96 h. Efficacy analyses were by intention to treat. This study is registered with ClinicalTrials.gov, number NCT01619969. FINDINGS We screened 69 patients and randomly assigned 50 (24 to celgosivir, 26 to placebo). Mean VLR was greater in the celgosivir group (-1·86, SD 1·07) than in the placebo group (-1·64, 0·75), but the difference was non-significant (-0·22, 90% CI -0·65 to 0·22; one-sided p=0·203). The mean AUC was also higher in the celgosivir group (54·92, SD 31·04) than in the placebo group (40·72, 18·69), but again the difference was non-significant (14·20, 90% CI 2·16-26·25; one-sided p=0·973). We noted similar incidences of adverse events between groups. INTERPRETATION Although generally safe and well tolerated, celgosivir does not seem to reduce viral load or fever burden in patients with dengue. FUNDING STOP Dengue Translational Clinical Research.

Rabies Postexposure Prophylaxis in a UK Travel Clinic: Ten Years' Experience

BACKGROUND In 2009, 58.6 million UK residents traveled abroad. Of these, 49.5 million (84.5%) visits were to Europe and North America and 9.1 million (15.5%) were to other parts of the world. Rabies is widely distributed and continues to be a major public health issue in many developing countries. The UK is free of rabies in carnivore host species, although cases of rabies in bats have been reported. This study examined the rabies postexposure prophylaxis (PEP) service from 2000 to July 2009 at the Liverpool School of Tropical Medicine. METHODS Medical records of patients who attended the clinic for rabies PEP were reviewed. RESULTS During the study period, 139 patients were treated for possible rabies exposure. The mean age was 35 years. Thailand and Turkey each accounted for 31 (22.3%) cases. Sixty-nine (49.6%) of those seen were due to dog bites. Most injuries involved a lower limb (n = 67, 48.2%) or hands (n = 26, 18.7%). Eighty-six (61.9%) cases had initiated rabies PEP overseas, but only 3 of the 78 (3.8%) meeting UK criteria for rabies immunoglobulin (RIG) received it while overseas. Only an additional 11 patients received RIG on return to the UK; most were seen more than 7 days after initiation of PEP. The median time from exposure to receiving rabies PEP was 1 day (range: 0-1,720). Only 14 (10.1%) had received preexposure rabies vaccination. CONCLUSIONS The majority of travelers seeking PEP at this clinic initiated treatment overseas. Most had not received RIG abroad, when it would have been appropriate. Initiation of appropriate treatment is often delayed and is a concern to those without preexposure rabies immunization. In view of the scarcity of RIG, travelers need to be aware of the risks, consider preexposure immunization, and present early for PEP.

Tropical Fungal Infections

Fungal infections are more common and diverse in the tropics but are also increasingly seen in returning travelers and migrants as international travel becomes easier. They are conventionally classified into superficial, cutaneous, subcutaneous, and systemic mycoses. This article provides an overview of superficial, cutaneous, and subcutaneous mycoses that are more prevalent and/or geographically restricted to the tropics and briefly discusses fungal infections in returning travelers. Systematic data on such infections as travel-associated diseases are currently lacking, and enhanced surveillance for fungal infections may lead to early diagnosis and an understanding of the epidemiology of the fungal infections among travelers.

blaOXA-181–positive Klebsiella pneumoniae, Singapore

To the Editor: Nordmann et al. (1) raised concern over the global spread of carbapenemase-producing Enterobacteriaceae. In their article, they called attention to the oxacillinase-48 (OXA-48) type carbapenemases because bacteria that produce these enzymes do not have a distinctive antimicrobial drug susceptibility profile, and there is less awareness of this mechanism of carbapenem resistance. We report the recent isolation of blaOXA-181–positive Klebsiella pneumoniae from 2 patients from Bangladesh who were admitted to separate hospitals in Singapore within a short period of each other.

Cross-reactive antibodies enhance live attenuated virus infection for increased immunogenicity.

Vaccination has achieved remarkable successes in the control of childhood viral diseases. To control emerging infections, however, vaccines will need to be delivered to older individuals who, unlike infants, probably have had prior infection or vaccination with related viruses and thus have cross-reactive antibodies against the vaccines. Whether and how these cross-reactive antibodies impact live attenuated vaccination efficacy is unclear. Using an open-label randomized trial design, we show that subjects with a specific range of cross-reactive antibody titres from a prior inactivated Japanese encephalitis vaccination enhanced yellow fever (YF) immunogenicity upon YF vaccination. Enhancing titres of cross-reactive antibodies prolonged YF vaccine viraemia, provoked greater pro-inflammatory responses, and induced adhesion molecules intrinsic to the activating Fc-receptor signalling pathway, namely immune semaphorins, facilitating immune cell interactions and trafficking. Our findings clinically demonstrate antibody-enhanced infection and suggest that vaccine efficacy could be improved by exploiting cross-reactive antibodies.

Extended Evaluation of Virological, Immunological and Pharmacokinetic Endpoints of CELADEN: A Randomized, Placebo-Controlled Trial of Celgosivir in Dengue Fever Patients.

CELADEN was a randomized placebo-controlled trial of 50 patients with confirmed dengue fever to evaluate the efficacy and safety of celgosivir (A study registered at ClinicalTrials.gov, number NCT01619969). Celgosivir was given as a 400 mg loading dose and 200 mg bid (twice a day) over 5 days. Replication competent virus was measured by plaque assay and compared to reverse transcription quantitative PCR (qPCR) of viral RNA. Pharmacokinetics (PK) correlations with viremia, immunological profiling, next generation sequence (NGS) analysis and hematological data were evaluated as exploratory endpoints here to identify possible signals of pharmacological activity. Viremia by plaque assay strongly correlated with qPCR during the first four days. Immunological profiling demonstrated a qualitative shift in T helper cell profile during the course of infection. NGS analysis did not reveal any prominent signature that could be associated with drug treatment; however the phylogenetic spread of patients’ isolates underlines the importance of strain variability that may potentially confound interpretation of dengue drug trials conducted during different outbreaks and in different countries. Celgosivir rapidly converted to castanospermine (Cast) with mean peak and trough concentrations of 5727 ng/mL (30.2 μM) and 430 ng/mL (2.3 μM), respectively and cleared with a half-life of 2.5 (± 0.6) hr. Mean viral log reduction between day 2 and 4 (VLR2-4) was significantly greater in secondary dengue than primary dengue (p = 0.002). VLR2-4 did not correlate with drug AUC but showed a trend of greater response with increasing Cmin. PK modeling identified dosing regimens predicted to achieve 2.4 to 4.5 times higher Cmin. than in the CELADEN trial for only 13% to 33% increase in overall dose. A small, non-statistical trend towards better outcome on platelet nadir and difference between maximum and minimum hematocrit was observed in celgosivir-treated patients with secondary dengue infection. Optimization of the dosing regimen and patient stratification may enhance the ability of a clinical trial to demonstrate celgosivir activity in treating dengue fever based on hematological endpoints. A new clinical trial with a revised dosing regimen is slated to start in 2016 (NCT02569827). Furthermore celgosivir’s potential value for treatment of other flaviruses such as Zika virus should be investigated urgently. Trial Registration: ClinicalTrials.gov NCT01619969

Prophylactic platelet transfusion plus supportive care versus supportive care alone in adults with dengue and thrombocytopenia: a multicentre, open-label, randomised, superiority trial

BACKGROUND Dengue is the commonest vector-borne infection worldwide. It is often associated with thrombocytopenia, and prophylactic platelet transfusion is widely used despite the dearth of robust evidence. We aimed to assess the efficacy and safety of prophylactic platelet transfusion in the prevention of bleeding in adults with dengue and thrombocytopenia. METHODS We did an open-label, randomised, superiority trial in five hospitals in Singapore and Malaysia. We recruited patients aged at least 21 years who had laboratory-confirmed dengue (confirmed or probable) and thrombocytopenia (≤20 000 platelets per μL), without persistent mild bleeding or any severe bleeding. Patients were assigned (1:1), with randomly permuted block sizes of four or six and stratified by centre, to receive prophylactic platelet transfusion in addition to supportive care (transfusion group) or supportive care alone (control group). In the transfusion group, 4 units of pooled platelets were given each day when platelet count was 20 000 per μL or lower; supportive care consisted of bed rest, fluid therapy, and fever and pain medications. The primary endpoint was clinical bleeding (excluding petechiae) by study day 7 or hospital discharge (whichever was earlier), analysed by intention to treat. Safety outcomes were analysed according to the actual treatment received. This study was registered with ClinicalTrials.gov, number NCT01030211, and is completed. FINDINGS Between April 29, 2010, and Dec 9, 2014, we randomly assigned 372 patients to the transfusion group (n=188) or the control group (n=184). The intention-to-treat analysis included 187 patients in the transfusion group (one patient was withdrawn immediately) and 182 in the control group (one was withdrawn immediately and one did not have confirmed or probable dengue). Clinical bleeding by day 7 or hospital discharge occurred in 40 (21%) patients in the transfusion group and 48 (26%) patients in the control group (risk difference -4·98% [95% CI -15·08 to 5·34]; relative risk 0·81 [95% CI 0·56 to 1·17]; p=0·16). 13 adverse events occurred in the transfusion group and two occurred in the control group (5·81% [-4·42 to 16·01]; 6·26 [1·43 to 27·34]; p=0·0064). Adverse events that were possibly, probably, or definitely related to transfusion included three cases of urticaria, one maculopapular rash, one pruritus, and one chest pain, as well as one case each of anaphylaxis, transfusion-related acute lung injury, and fluid overload that resulted in serious adverse events. No death was reported. INTERPRETATION In adult patients with dengue and thrombocytopenia, prophylactic platelet transfusion was not superior to supportive care in preventing bleeding, and might be associated with adverse events. FUNDING National Medical Research Council, Singapore.

An accelerated rabies vaccine schedule based on toll-like receptor 3 (TLR3) agonist PIKA adjuvant augments rabies virus specific antibody and T cell response in healthy adult volunteers

BACKGROUND Rabies is a fatal disease where post-exposure prophylaxis (PEP) is crucial in preventing infection. However, deaths even after appropriate PEP, have been reported. The PIKA Rabies vaccine adjuvant is a TLR3 agonist that activates B and T cells leading to a robust immune response. METHODS We conducted a phase I, open label, randomized study in healthy adults to assess the safety and immunogenicity of the PIKA Rabies vaccine and an accelerated vaccine regimen. Thirty-seven subjects were randomized into 3 groups: control vaccine classic regimen, PIKA vaccine classic regimen and PIKA vaccine accelerated regimen. Subjects were followed up for safety, rabies virus neutralizing antibodies (RVNA) and T cell responses. RESULTS Both the control and PIKA Rabies vaccine were well tolerated. All adverse events (AEs) were mild and self-limiting. Seventy-five percent of subjects in the PIKA accelerated regimen achieved a RVNA titer ⩾0.5IU/mL on day 7, compared to 53.9% in the PIKA classic regimen (p=0.411) and 16.7% in control vaccine classic regimen (p=0.012). The PIKA rabies vaccine elicited multi-specific rabies CD4 mediated T cell response already detectable ex vivo at day 7 after vaccination and that was maintained at day 42. CONCLUSION The investigational PIKA rabies vaccine was well tolerated and more immunogenic than the commercially available vaccine in healthy adults. Clinical trial registry: The study was registered with clinicaltrials.gov NCT02657161.

Diffusion-weighted MRI abnormalities in an outbreak of Streptococcus agalactiae Serotype III, multilocus sequence type 283 meningitis.

In 2015, an outbreak of group B streptococcal (GBS) infection caused by Streptococcus agalactiae Serotype III, multilocus sequence type 283, related to consuming infected raw freshwater fish, affected more than 200 patients in Singapore. We describe the clinical, laboratory, and neuroimaging features of a subgroup of adults with central nervous system (CNS) infections caused by GBS.

Management of healthcare-associated methicillin-resistant Staphylococcus aureus.

Healthcare-associated methicillin-resistant Staphylococcus aureus is a major cause of nosocomial infections worldwide, with significant attributable morbidity and mortality in addition to pronounced healthcare costs. Treatment results with vancomycin – the current recommended antibiotic for serious methicillin-resistant S. aureus infections – have not been impressive. The recent availability of effective antimicrobial agents other than glycopeptides, such as linezolid and daptomycin, as well as the anticipated approval of newer agents with diverse mechanisms of action, has somewhat ameliorated the threat posed by this organism. However, these drugs are expensive, and there is still no overall satisfactory strategy for reducing the incidence of healthcare-associated methicillin-resistant S. aureus in endemic regions. Although early results with the Society for Healthcare Epidemiology of America guidelines give cause for cautious optimism, long-term experience is lacking, and it is likely that these guidelines will have to be adapted according to local conditions and resources before implementation. Trends to keep in mind when considering the problem of healthcare-associated methicillin-resistant S. aureus include the advent of community-associated methicillin-resistant S. aureus, and the propensity of S. aureus to evolve and acquire resistance determinants over time. This was last vividly demonstrated by the handful of vancomycin-resistant S. aureus isolated recently, which had acquired the vancomycin resistance gene from vancomycin-resistant enterococci.