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Background: New Delhi metallo-β-lactamase (blaNDM), a plasmid-borne carbapenemase gene associated with significant mortality and severely limited treatment options, is of global public health concern as it is found in extremely diverse Gram-negative bacterial strains. This study thus aims to genetically characterize local and global spread of blaNDM. Methods: To investigate local transmission patterns in the context of a single hospital, whole genome sequencing data of the first 11 blaNDM-positive bacteria isolated in a local hospital were analyzed to: (1) identify and compare blaNDM-positive plasmids; and (2) study the phylogenetic relationship of the bacteria chromosomes. The global analysis was conducted by analyzing 2749 complete plasmid sequences (including 39 blaNDM-positive plasmids) in the NCBI database, where: (1) the plasmids were clustered based on their gene composition similarity; (2) phylogenetic study was conducted for each blaNDM-positive plasmid cluster to infer the phylogenetic relationship within each cluster; (3) gene transposition events introducing blaNDM into different plasmid backbones were identified; and (4) clustering pattern was correlated with the plasmids' incompatibility group and geographical distribution. Results: Analysis of the first 11 blaNDM-positive isolates from a single hospital revealed very low blaNDM-positive plasmid diversity. Local transmission was characterized by clonal spread of a predominant plasmid with 2 sporadic instances of plasmid introduction. In contrast to the low diversity locally, global blaNDM spread involved marked plasmid diversity with no predominant bacterial clone. Thirty-nine (1.4 %) out of the 2749 complete plasmid sequences were blaNDM-positive, and could be resolved into 7 clusters, which were associated with plasmid incompatibility group and geographical distribution. The blaNDM gene module was witnessed to mobilize between different plasmid backbones on at least 6 independent occasions. Conclusions: Our analysis revealed the complex genetic pathways of blaNDM spread, with global dissemination characterized mainly by transposition of the blaNDM gene cassette into varied plasmids. Early local transmission following plasmid introduction is characterized by plasmid conjugation and bacterial spread. Our findings emphasize the importance of plasmid molecular epidemiology in understanding blaNDM spread. [ABSTRACT FROM AUTHOR]

Herpes zoster reactivation occurs in patients who had primary varicella infection, afflicting mainly the elderly and the immunocompromised. However, it is rare that varicella infection develop after zoster reactivation. We report on a patient with underlying HIV/AIDS who had two previous episodes of herpes zoster and still developed varicella infection, complicated by pneumonitis and polyradiculitis. We also review the relevant literature.

Introduction: The current avian and human H5N1 influenza epidemic has been in resurgence since 2004. We decided to evaluate published evidence in relation to epidemiology, clinical features and course, laboratory diagnosis, treatment and outcome of human H5N1 influenza, and develop institutional clinical management guidelines., Methods: A search of PubMed was conducted for all English language articles with search terms "avian", "influenza" and "H5N1". The bibliography of articles was searched for other references of interest., Results: Published case series from Hong Kong in 1997, and Thailand and Vietnam since 2004 have indicated a rapidly progressive primary viral pneumonia resulting in acute respiratory distress syndrome. The majority of human H5N1 infections can be linked to poultry exposure. Hitherto there has been no evidence of efficient human-to-human transmission. Case fatality rates have varied from 71% in Thailand to 100% in Cambodia. Oseltamivir appears to be the only potentially effective antiviral therapy. H5N1 isolates in Vietnam have become resistant to oseltamivir, resulting in persistent viral replication and death. There is as yet no effective human H5N1 vaccine., Conclusions: National and international preparedness plans are well advised. Clinical trials to evaluate higher dose oseltamivir therapy and immunomodulatory treatment are urgently needed.

Introduction: The outbreak of severe acute respiratory syndrome (SARS) began after the index case was admitted on 1 March 2003. We profile the cases suspected to have acquired the infection in Tan Tock Seng Hospital (TTSH), focussing on major transmission foci, and also describe and discuss the impact of our outbreak control measures., Materials and Methods: Using the World Health Organization (WHO) case definitions for probable SARS adapted to the local context, we studied all cases documented to have passed through TTSH less than 10 days prior to the onset of fever. Key data were collected in liaison with clinicians and through a team of onsite epidemiologists., Results: There were 105 secondary cases in TTSH. Healthcare staff (57.1%) formed the majority, followed by visitors (30.5%) and inpatients (12.4%). The earliest case had onset of fever on 4 March 2003, and the last case, on 5 April 2003. Eighty-nine per cent had exposures to 7 wards which had cases of SARS that were not isolated on admission. In 3 of these wards, major outbreaks resulted, each with more than 20 secondary cases. Attack rates amongst ward-based staff ranged from 0% to 32.5%. Of 13 inpatients infected, only 4 (30.8%) had been in the same room or cubicle as the index case for the ward., Conclusions: The outbreak of SARS at TTSH showed the challenges of dealing with an emerging infectious disease with efficient nosocomial spread. Super-spreading events and initial delays in outbreak response led to widespread dissemination of the outbreak to multiple wards.