Viral RNA Degradation Makes Urine a Challenging Specimen for Detection of Japanese Encephalitis Virus in Patients With Suspected CNS Infection

Background

Japanese encephalitis virus (JEV) is a leading cause of central nervous system (CNS) infections in Asia and results in significant morbidity and mortality. JEV RNA is rarely detected in serum or cerebrospinal fluid (CSF), and diagnosis of JEV infection is usually based on serological tests that are frequently difficult to interpret. Unlike serum or CSF, urine is relatively easy to obtain, but, to date, there has been minimal work on the feasibility of testing urine for JEV RNA.

Methods

We investigated the use of lysis buffer and a Microsep device to optimize urine storage for detection of JEV RNA by reverse transcription real-time polymerase chain reaction (RT-qPCR). The best of the studied methods was then evaluated in consecutive patients admitted to the hospital with suspected CNS infections in Laos.

Results

We demonstrated degradation of JEV RNA in urine after even short storage periods at 4°C or –80°C. Although there was no advantage in using a Microsep concentration device alone, immediate addition of lysis buffer to fresh urine improved the detection of JEV RNA at the limit of detection.

Conclusions

In 2 studies of 41 patients with acute encephalitis syndrome, 11 (27%) were positive for JEV IgM in CSF and/or serum, and 2 (4.9%) were JEV RT-qPCR positive from throat swabs. JEV RNA was not detected in any of these patients’ urine samples. However, lysis buffer was only used during a prospective study, that is, for only 17/41 (41%) patient urine samples. Our findings suggest a need for larger studies testing urine for JEV RNA, with urine collected at different times from symptom onset, and using lysis buffer, which stabilizes RNA, for storage.

Association between reported aetiology of central nervous system infections and the speciality of study investigators-a bias compartmental syndrome?

Background

Conventional descriptions of central nervous system (CNS) infections are variably categorized into clinical syndromes for patient investigation, management and research. Aetiologies of the most commonly recognized syndromes, encephalitis and meningitis, tend to be attributed predominantly to viruses and bacteria, respectively.

Methods

A systematic review was performed of aetiological studies of CNS syndromes and data extracted on reported author specialities.

Results

The analysis identified an association between the author's speciality and the CNS syndrome studied, with a tendency for virologists to study encephalitis and microbiologists to study meningitis.

Conclusions

We suggest there is bias in study design. Stronger multidisciplinary collaboration in CNS infection research is needed.

Hepatitis E infection in stem cell and solid organ transplantpatients: A cross-sectional study: The importance of HEV RNA screening in peri-transplant period

BACKGROUND

Hepatitis E Virus (HEV) is a common cause of acute viral hepatitis worldwide. Typically associated with a self-limiting illness, infection may persist in immunosuppressed populations with significant morbidity and mortality. Based on clinical data published world-wide, UK blood safety guidance recommends the universal screening for HEV RNA of blood donors and donors of tissue, organs and stem cells.

OBJECTIVES

This cross-sectional study aimed to determine the point prevalence of HEV viraemia and clinical course of viraemic patients in the peri-transplant period in solid organ transplant (SOT) and haematopoietic stem cell transplant (HSCT) recipients transplanted over a 3-year period (2013-2015).

STUDY DESIGN

Nucleic acid extracts of whole blood from patients undergoing SOT or HSCT were tested by an in-house real-time reverse-transcriptase polymerase chain reaction assay for HEV RNA. Samples were tested at baseline (time of transplant), 30, 60 and 90 days post-transplant.

RESULTS

870 patients (259 HSCT, 262 liver and 349 kidney transplant) were included with 2554 samples meeting the inclusion criteria. No kidney transplant patients had HEV viraemia at time of testing. One HSCT and three liver transplant patients were found to be HEV RNA positive. Overall this represented 0.46% of the patients testing positive for HEV viraemia.

CONCLUSIONS

Prevalence of HEV viraemia in SOT and HSCT patients in U.K. although higher than in the general population is low at baseline and remains low throughout the early post-transplant phase. Clearance of viraemia can be maintained despite ongoing immunosuppression. Prospective U.K. studies are necessary to inform screening policies in this population.

'Montezuma's revenge': neurological disorders in the returning traveller

'The world is a book and those who do not travel read only one page'.Augustine of Hippo - Latin philosopher and theologian.Neurological presentations are seen in about 1.5%-2.0% of returning travellers seeking medical attention, and may pose a particular challenge to diagnose and treat. These may be severe and life threatening, such as meningoencephalitic illnesses or inflammatory radiculoneuropathy (Guillain-Barré-like) syndromes requiring intensive care support. It is essential not to miss the potentially treatable and common diseases such as malaria, which can be lethal if undiagnosed. Herpes simplex virus remains the most common cause of encephalitis in returning travellers to the UK. Furthermore, common bacterial conditions such as pneumococcal meningitis may be associated with different resistance patterns globally, and this must be taken into account in treatment decisio.ns. This review provides a clinical approach, illustrated with a range of cases, and suggestions where to get further management advice.

Angiostrongylus cantonensis DNA in Cerebrospinal Fluid of Persons with Eosinophilic Meningitis, Laos

Definitive identification of Angiostrongylus cantonensis parasites from clinical specimens is difficult. As a result, regional epidemiology and burden are poorly characterized. To ascertain presence of this parasite in patients in Laos with eosinophilic meningitis, we performed quantitative PCRs on 36 cerebrospinal fluid samples; 4 positive samples confirmed the parasite’s presence.

Detection of Japanese Encephalitis Virus RNA in Human Throat Samples in Laos - A Pilot study

Japanese encephalitis virus (JEV) is the most commonly identified cause of acute encephalitis syndrome (AES) in Asia. The WHO recommended test is anti-JEV IgM-antibody-capture-enzyme-linked-immunosorbent-assay (JEV MAC-ELISA). However, data suggest this has low positive predictive value, with false positives related to other Flavivirus infections and vaccination. JEV RT-PCR in cerebrospinal fluid (CSF) and/or serum is highly specific, but is rarely positive; 0-25% of patients that fulfil the WHO definition of JE (clinical Acute Encephalitis Syndrome (AES) and JEV MAC-ELISA positive). Testing other body fluids by JEV RT-qPCR may improve the diagnosis. As a pilot study thirty patients admitted to Mahosot Hospital 2014-2017, recruited to the South-East-Asia-Encephalitis study, were tested by JEV MAC-ELISA and two JEV real-time RT-PCR (RT-qPCR) assays (NS2A and NS3). Eleven (36.7%) were JEV MAC-ELISA positive. Available CSF and serum samples of these patients were JEV RT-qPCR negative but 2 (7%) had JEV RNA detected in their throat swabs. JEV RNA was confirmed by re-testing, and sequencing of RT-qPCR products. As the first apparent report of JEV RNA detection in human throat samples, the provides new perspectives on human JEV infection, potentially informing improving JEV detection. We suggest that testing patients' throat swabs for JEV RNA is performed, in combination with molecular and serological CSF and serum investigations, on a larger scale to investigate the epidemiology of the presence of JEV in human throats. Throat swabs are an easy and non-invasive tool that could be rolled out to a wider population to improve knowledge of JEV molecular epidemiology.

A case of NDM-carbapenemase-producing hypervirulent Klebsiella pneumoniae sequence type 23 from the UK

Introduction

Hypervirulent capsular type K1 Klebsiella pneumoniae strains of clonal complex 23 (CC23) are associated with severe community-acquired pyogenic liver abscesses, often complicated by metastatic infections and significant mortality. The majority of hypervirulent strains reported are susceptible to most antibiotics except ampicillin. To the best of our knowledge, this is the first case of New Delhi metallo-β-lactamase (bla_NDM)-producing hypervirulent K. pneumoniae from the UK.

Case presentation

We present a case of pyogenic liver abscess in a 63-year-old female of Bangladeshi origin, with a recent diagnosis of pancreatic cancer. The patient was treated with piperacillin/tazobactam and blood cultures grew a fully susceptible Escherichia coli. Despite antimicrobial therapy and drainage of the abscess, the patient continued to deteriorate and died on day seven of admission. The fluid drained from the liver abscess grew a fully susceptible E. coli and a multi-drug-resistant K. pneumoniae. Two weeks prior to admission, a rectal screening swab grew a metallo-β-lactamase-producing K. pneumoniae. Molecular characterization revealed that both the K. pneumoniae isolates belonged to the hypervirulent K1 cluster of CC23, sequence type 23. The isolate from the rectal screen was positive for the bla_NDM metallo-β-lactamase gene.

Conclusion

The emergence of carbapenemase-producing hypervirulent K. pneumoniae strains presents a new and significant threat to global public health. Management of these infections will be extremely challenging due to the limited treatment options available and they are likely to be associated with an even greater mortality.

Encephalitis diagnosis using metagenomics: application of next generation sequencing for undiagnosed cases

BACKGROUND

Current estimates suggest that even in the most resourced settings, the aetiology of encephalitis is identified in less than half of clinical cases. It is acknowledged that filling this gap needs a combination of rigorous sampling and improved diagnostic technologies. Next generation sequencing (NGS) methods are powerful tools with the potential for comprehensive and unbiased detection of pathogens in clinical samples. We reviewed the use of this new technology for the diagnosis of suspected infectious encephalitis, and discuss the feasibility for introduction of NGS methods as a frontline diagnostic test.

METHODS

A systematic literature review was performed, using MESH and text word searches for variants of "sequencing" and "encephalitis" in Medline and EMbase, and searching bibliographies and citations using the Web of Science database. Two authors independently reviewed, extracted and summarised data.

FINDINGS

The review identified 25 articles reporting 44 case reports of patients with suspected encephalitis for whom NGS was used as a diagnostic tool. We present the data and highlight themes arising from these cases. There are no randomly controlled trials to assess the utility of NGS as a diagnostic tool.

INTERPRETATION

There is increasing evidence of a role for NGS in the work-up of undiagnosed encephalitis. Lower costs and increasing accessibility of these technologies will facilitate larger studies of these patients. We recommend NGS should be considered as a front-line diagnostic test in chronic and recurring presentations and, given current sample-to-result turn-around times, as second-line in acute cases of encephalitis.

A critical appraisal of 'Shingrix', a novel herpes zoster subunit vaccine (HZ/Su or GSK1437173A) for varicella zoster virus

HZ/Su, branded as 'Shingrix', is one of the newest vaccines to be submitted for multi-national regulatory approval. It is targeted to prevent shingles, a global concern with aging populations. A live attenuated vaccine for shingles has been available for over a decade, however it is contraindicated in specific subgroups of people, and there are added concerns regarding long-term immunogenicity. HZ/Su is the first subunit vaccine developed to protect against shingles. This paper provides a critical appraisal of current evidence regarding HZ/Su.

Poor performance of two rapid immunochromatographic assays for anti-Japanese encephalitis virus immunoglobulin M detection in cerebrospinal fluid and serum from patients with suspected Japanese encephalitis virus infection in Laos

Background

Japanese encephalitis virus (JEV) is a leading identified cause of encephalitis in Asia, often occurring in rural areas with poor access to laboratory diagnostics. We evaluated two rapid diagnostic tests (RDTs) for anti-JEV immunoglobulin M (IgM) detection.

Methods

Consecutive cerebrospinal fluid and serum from 388 patients (704 samples) with suspected JEV infections admitted to six hospitals in Laos were tested with one of two SD-Bioline anti-JEV IgM RDTs and the World Health Organization standard anti-JEV IgM enzyme-linked immunosorbent assay (ELISA; Panbio Japanese Encephalitis–Dengue IgM Combo ELISA.

Results and Conclusions

The performance of both RDTs showed strikingly low sensitivity in comparison to anti-JEV IgM antibody capture ELISA (2.1–51.4%), suggesting low sensitivity of the RDTs. We highlight the fundamental prerequisite to validate RDTs prior to use to ensure that they meet standards for testing.

Diagnostic yield of FDG-PET/CT in fever of unknown origin: a systematic review, meta-analysis, and Delphi exercise

AIM

To perform a systematic review, meta-analysis and Delphi exercise to evaluate diagnostic yield of combined 2-[¹⁸F]-fluoro-2-deoxy-d-glucose (FDG) positron-emission tomography and computed tomography (FDG-PET/CT) in fever of unknown origin (FUO).

MATERIALS AND METHODS

Four databases were searched for studies of FDG-PET/CT in FUO 1/1/2000-1/12/2015. Exclusions were non-English language, case reports, non-standard FDG radiotracer, and significant missing data. Quality was assessed by two authors independently using a standardised tool. Pooled diagnostic yield was calculated using a random-effects model. An iterative electronic and face-to-face Delphi exercise generated interspeciality consensus.

RESULTS

Pooled diagnostic yield was 56% (95% confidence interval [CI]: 50-61%, I²=61%) from 18 studies and 905 patients. Only five studies reported results of previous imaging, and subgroup analysis estimated diagnostic yield beyond conventional CT at 32% (95% CI: 22-44%; I²=66%). Consensus was established that FDG-PET/CT is increasingly available with an emerging role, but there is prevailing variability in practice.

CONCLUSION

There is insufficient evidence to support the value of FDG-PET/CT in investigative algorithms of FUO. A paradigm shift in research is needed, involving prospective studies recruiting at diagnosis of FUO, with updated case definitions and hard outcome measures. Although these studies will be a significant undertaking with multicentre collaboration, their completion is vital for balancing both radiation exposure and costs against the possible benefits of utilising FDG-PET/CT.

Pyrexia of unknown origin in clinical practice

This article revisits concepts of pyrexia of unknown origin to reflect current clinical practice. It describes the evolution of the term, in line with the changing spectrum and pace of investigations, and introduces key questions that may be used to evaluate a pyrexia of unknown origin.

Ochromobactrum intermedium: an emerging opportunistic pathogen-case of recurrent bacteraemia associated with infective endocarditis in a haemodialysis patient

We describe the first clinical case report of infective endocarditis related to Ochrobactrum intermedium infection. The case involved a 23-year-old man receiving dialysis via an internal jugular long-term haemodialysis catheter. He improved with a prolonged course of meropenem and minocycline. Ochrobactrum spp. are recognized as rare emerging opportunistic pathogens.