Prolonged viral shedding was noted in young immunocompetent adults with mild pandemic influenza (H1N1) 2009 despite receipt of oseltamivir. When prescribed during the first 3 days of illness, oseltamivir shortened the duration of viral shedding.

BackgroundIn the past decade, several countries have seen gradual replacement of endemic multi-resistant healthcare-associated methicillin-resistant Staphylococcus aureus (MRSA) with clones that are more susceptible to antibiotic treatment. One example is Singapore, where MRSA ST239, the dominant clone since molecular profiling of MRSA began in the mid-1980s, has been replaced by ST22 isolates belonging to EMRSA-15, a recently emerged pandemic lineage originating from Europe.ResultsWe investigated the population structure of MRSA in Singaporean hospitals spanning three decades, using whole genome sequencing. Applying Bayesian phylogenetic methods we report that prior to the introduction of ST22, the ST239 MRSA population in Singapore originated from multiple introductions from the surrounding region; it was frequently transferred within the healthcare system resulting in a heterogeneous hospital population. Following the introduction of ST22 around the beginning of the millennium, this clone spread rapidly through Singaporean hospitals, supplanting the endemic ST239 population. Coalescent analysis revealed that although the genetic diversity of ST239 initially decreased as ST22 became more dominant, from 2007 onwards the genetic diversity of ST239 began to increase once more, which was not associated with the emergence of a sub-clone of ST239. Comparative genomic analysis of the accessory genome of the extant ST239 population identified that the Arginine Catabolic Mobile Element arose multiple times, thereby introducing genes associated with enhanced skin colonization into this population.ConclusionsOur results clearly demonstrate that, alongside clinical practice and antibiotic usage, competition between clones also has an important role in driving the evolution of nosocomial pathogen populations.Electronic supplementary materialThe online version of this article (doi:10.1186/s13059-015-0643-z) contains supplementary material, which is available to authorized users.

Multidrug-resistant Gram-negative bacteria (MDR-GNB) are an emerging public health threat. Accurate estimates of their clinical impact are vital for justifying interventions directed towards preventing or managing infections caused by these pathogens. A retrospective observational cohort study was conducted between 1 January 2007 and 31 July 2009, involving subjects with healthcare-associated and nosocomial Gram-negative bacteraemia at two large Singaporean hospitals. Outcomes studied were mortality and length of stay post-onset of bacteraemia in survivors (LOS). There were 675 subjects (301 with MDR-GNB) matching study inclusion criteria. On multivariate analysis, multidrug resistance was not associated with 30-day mortality, but it was independently associated with longer LOS in survivors (coefficient, 0.34; 95% CI, 0.21-0.48; p < 0.001). The excess LOS attributable to multidrug resistance after adjustment for confounders was 6.1 days. Other independent risk factors for higher mortality included male gender, higher APACHE II score, higher Charlson comorbidity index, intensive care unit stay and presence of concomitant pneumonia. Concomitant urinary tract infection and admission to a surgical discipline were associated with lower risk of mortality. Appropriate empirical antibiotic therapy was neither associated with 30-day mortality nor LOS, although the study was not powered to assess this covariate adequately. Our study adds to existing evidence that multidrug resistance per se is not associated with higher mortality when effective antibiotics are used for definitive therapy. However, its association with longer hospitalization justifies the use of control efforts.

Summaryobjectives To assess whether the clinical and laboratory methods for diagnosing Strongyloides stercoralis infection in non-endemic countries is different between those who are chronically exposed and those who travel.methods Analysis of laboratory and clinical data from 204 patients having S. stercoralis infection at the Hospital for Tropical Diseases, London.results Sixty-four travellers and 128 immigrants from endemic countries had laboratory-proven strongyloides. In those with microscopically proven disease, serology was 73% sensitive in travellers and 98% sensitive in immigrants (P < 0.001). There was no difference in the eosinophil count between the two groups with 19% having a normal count. Patterns of symptoms varied between the groups, and around one-third were asymptomatic in both groups. Serology was of limited use in follow-up.conclusions Eosinophil count and stool microscopy are insufficiently sensitive to be used alone for screening strongyloides. The sensitivity of serology is good in immigrants with chronic infection, but lower in travellers.

A new national antimicrobial resistance surveillance program in Singapore public hospitals that uses WHONET detected high levels of methicillin resistance among Staphylococcus aureus (35.3%), carbapenem resistance among Acinetobacter spp. (49.6%), and third-generation cephalosporin resistance among Klebsiella pneumoniae (35.9%) hospital isolates in 2006. Antimicrobial drug resistance is a major problem in Singapore.

The emergence of carbapenemase-producing Enterobacteriaceae is a rapidly evolving threat worldwide. Here, we report the molecular characterization of two Klebsiella pneumoniae isolates carrying both bla(OXA -181) and bla(NDM -1) or bla(NDM -5) isolated from epidemiologically unrelated patients in Singapore. The bla(OXA -181) genes were found existing in different genetic environments.

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Background. Since 2010, the incidence of carbapenem-resistant Enterobacteriaceae (CRE) has been increasing in Singapore. We analyzed the clinical and molecular epidemiology of CRE among adult inpatients in Singapore.Methods. Quarterly incidence of unique subjects (per 100 000 patient-days) with positive clinical and surveillance cultures for CRE were estimated based on mandatory data submitted to the National Public Health Laboratory by public hospitals between 2010 and 2015. CRE-positive adult inpatients were prospectively recruited from 6 public sector hospitals between December 2013 and April 2015. Subjects answered a standardized epidemiologic questionnaire and provided samples for this study. Further clinical information was extracted from subjects' electronic medical records. Whole-genome sequencing was performed on study isolates to determine transmission clusters.Results. Incidence of CRE clinical cultures among adult inpatients plateaued from 2013 (range: 7.73 to 10.32 per 100 000 patient-days) following an initial increase between 2010 and end-2012. We prospectively recruited 249 subjects. Their median age was 65 years, 108 (43%) were female, and 161 (64.7%) had carbapenemase-producing Enterobacteriaceae (CPE). On multivariate analysis, prior carbapenem exposure (OR: 3.23; 95% CI: 1.67-6.25) and hematological malignancies (OR: 2.85; 95% CI: 1.10-7.41) were associated with non-carbapenemase-producing CRE (NCPE) (n = 88) compared with CPE (n = 161) subjects. Among 430 CRE isolates from the 249 subjects, 307(71.3%) were CPE, of which 154(50.2%) were bla KPC -positive, 97(31.6%) bla NDM -positive, and 42 (13.7%) bla OXA -positive. Klebsiella pneumoniae (n = 180, 41.9%), Escherichia coli (n = 129, 30.0%) and Enterobacter cloacae (n = 62, 14.4%) were the main Enterobacteriaceae species. WGS (n = 206) revealed diverse bacterial strain type (STs). The predominant bla KPC -positive plasmid was pHS102707 (n = 62, 55.4%) and the predominant bla NDM -positive plasmid was pNDM-ECS01 (n = 46, 48.9%). Five transmission clusters involving 13 subjects were detected.Conclusions. Clinical CRE trend among adult inpatients showed stabilization following a rapid rise since introduction in 2010 potentially due to infection prevention measures and antimicrobial stewardship. More work is needed on understanding CPE transmission dynamics.