Infectious disease emergencies

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Molecular diagnostics in tuberculosis

Molecular diagnostics in tuberculosis has enabled rapid detection of Mycobacterium tuberculosis complex in clinical specimens, identification of mycobacterial species, detection of drug resistance, and typing for epidemiological investigation. In the laboratory diagnosis of tuberculosis, the nucleic acid amplification (NAA) test is rapid and specific but not as sensitive as culture of mycobacteria. The primary determinant of successful NAA testing for tuberculosis depends on the shedding of mycobacterial DNA in secretions from caseating granulomas and its dissemination into sterile body fluids or tissue biopsies. In multibacillary diseases with a high mycobacterial load, a positive Ziehl-Neelsen smear with a positive NAA test is diagnostic of active tuberculosis, whereas a positive Ziehl-Neelsen smear with a negative NAA test in the absence of inhibitors would indicate nontuberculous mycobacterial disease. The role of the NAA test is more important in paucibacillary diseases with low mycobacterial loads. The presence of polymerase chain reaction (PCR) inhibitors, however, especially in extrapulmonary specimens, may produce false-negative results. Although this problem can be overcome to some extent by extra extraction steps, the additional processing invariably leads to the loss of mycobacterial DNA. To circumvent this problem, a brief culture augmentation step is carried out before the NAA test is performed, which can enhance the mycobacterial load while concomitantly diluting inhibitors, thereby maintaining the sensitivity of the test without excessively increasing turnaround time. © Springer-Verlag 2005.postprin

Effect of applying the new clinical and laboratory standards institute ticarcillin/clavulanic acid, piperacillin, piperacillin/tazobactam and imipenem susceptibility breakpoints for Pseudomonas aeruginosa in Hong Kong

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Paradoxical deterioration during anti-tubercular treatment in a dialysis patient on maintenance steroid therapy

We report a 38-year-old Chinese woman with lupus nephritis on peritoneal dialysis and long-term maintenance steroid therapy. This patient developed paradoxical deterioration during anti-tubercular therapy for tuberculous lymphadenitis. The deterioration resolved spontaneously without change to pharmacotherapy. Paradoxical deterioration that may spontaneously resolve is a potential complication of anti-tubercular treatment in patients on long-term renal replacement therapy.published_or_final_versio

Comparative host gene transcription by microarray analysis early after infection of the Huh7 cell line by SARS coronavirus and human coronavirus 229E

During the early stages of infection, SARS-CoV produces more severe perturbation of host cell gene expression in a human epithelial cell line of liver origin than the HCoV-229E.published_or_final_versio

Emergence of NDM-1-producing Enterobacteriaceae in China

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Medical treatment of viral pneumonia including SARS in immunocompetent adult

Since no randomized controlled trials have been conducted on the treatment of viral pneumonia by antivirals or immunomodulators in immunocompetent adults, a review of such anecdotal experience are needed for the more rational use of such agents. Case reports (single or case series) with details on their treatment and outcome in the English literature can be reviewed for pneumonia caused by human or avian influenza A virus (50 patients), varicella zoster virus (120), adenovirus (29), hantavirus (100) and SARS coronavirus (SARS-CoV) (841). Even with steroid therapy alone, the mortality rate appeared to be lower when compared with conservative treatment for pneumonia caused by human influenza virus (12.5% vs. 42.1%) and hantavirus (13.3% vs. 63.4%). Combination of an effective antiviral, acyclovir, with steroid in the treatment of varicella zoster virus may be associated with a lower mortality than acyclovir alone (0% vs. 10.3%). Combination of interferon alfacon-1 plus steroid, or lopinavir/ritonavir, ribavirin plus steroid were associated with a better outcome than ribavirin plus steroid (0% vs. 2.3% vs. 7.7%, respectively). Combination of lopinavir/ritonavir plus ribavirin significantly reduced the virus load of SARS-CoV in nasopharyngeal, serum, stool and urine specimens taken between day 10 and 15 after symptom onset when compared with the historical control group treated with ribavirin. It appears that the combination of an effective antiviral and steroid was associated with a better outcome. Randomized therapeutic trial should be conducted to ascertain the relative usefulness of antiviral alone or in combination with steroid. © 2004 The British Society. Published by Elsevier Ltd. All rights reserved.postprin

Middle East respiratory syndrome coronavirus: another zoonotic betacoronavirus causing SARS-like disease

The source of the severe acute respiratory syndrome (SARS) epidemic was traced to wildlife market civets and ultimately to bats. Subsequent hunting for novel coronaviruses (CoVs) led to the discovery of two additional human and over 40 animal CoVs, including the prototype lineage C betacoronaviruses, Tylonycteris bat CoV HKU4 and Pipistrellus bat CoV HKU5; these are phylogenetically closely related to the Middle East respiratory syndrome (MERS) CoV, which has affected more than 1,000 patients with over 35% fatality since its emergence in 2012. All primary cases of MERS are epidemiologically linked to the Middle East. Some of these patients had contacted camels which shed virus and/or had positive serology. Most secondary cases are related to health care-associated clusters. The disease is especially severe in elderly men with comorbidities. Clinical severity may be related to MERS-CoV's ability to infect a broad range of cells with DPP4 expression, evade the host innate immune response, and induce cytokine dysregulation. Reverse transcription-PCR on respiratory and/or extrapulmonary specimens rapidly establishes diagnosis. Supportive treatment with extracorporeal membrane oxygenation and dialysis is often required in patients with organ failure. Antivirals with potent in vitro activities include neutralizing monoclonal antibodies, antiviral peptides, interferons, mycophenolic acid, and lopinavir. They should be evaluated in suitable animal models before clinical trials. Developing an effective camel MERS-CoV vaccine and implementing appropriate infection control measures may control the continuing epidemic. © 2015, American Society for Microbiology. All Rights Reserved.postprin

Clinical characteristics and risk factors of herpes zoster after bone marrow transplantation

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Clinical outcome of extended-spectrum beta-lactamase-producing Escherichia coli bacteremia in an area with high endemicity

Objectives: This study assessed the impact of discordant empirical antibiotic therapy on the outcome of bacteremia caused by extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli. Methods: The clinical features and outcomes of a cohort of patients hospitalized with ESBL E. coli bacteremia between 2007 and 2008 were retrospectively reviewed. The effect of different antimicrobial regimens on patient outcomes was analyzed. Results: ESBL E. coli accounted for 24.2% (207/857) of E. coli bacteremia cases. The urinary tract (43.6%) was the most common source of infection, followed by the hepatobiliary tract (23.0%). Discordant empirical antibiotic therapy was given to 52.0% patients. Admission to the intensive care unit was associated with the use of a carbapenem as empirical antibiotic therapy (p<. 0.001). Univariate analysis revealed no significant differences in 30-day mortality rates between patients receiving concordant and discordant empirical antibiotic therapy (23.5% vs. 19.8%, p=. 0.526), carbapenem and non-carbapenem empirical antibiotic therapy (29.8% vs. 19.1%, p=. 0.118), beta-lactam/beta-lactam inhibitor combinations (BLBLIs) and non-BLBLIs empirical antibiotic therapy (20.3% vs. 22.3%, p=. 0.734), cephalosporin and non-cephalosporin empirical antibiotic therapy (19.7% vs. 22.6%, p=. 0.639), and fluoroquinolone and non-fluoroquinolone empirical antibiotic therapy (8.3% vs. 22.4%, p=. 0.251). The findings were confirmed by multivariate analysis. Conclusions: Despite a high proportion of discordant empirical antibiotic therapy, ESBL production had little effect on 30-day mortality. Whether the observation can be applied to different ESBL types is unknown and warrants further study. © 2012 International Society for Infectious Diseases.postprin