Cluster of invasive Mycobacteria chimaera infections following cardiac surgery demonstrating novel clinical features and risks of aortic valve replacement.

There is a global outbreak of infections due to Mycobacterium chimaera associated with cardiac surgery. The most serious infections involve prosthetic material implantation, and all have followed surgical procedures involving cardiopulmonary bypass. We describe a cluster of four cases following cardiac surgery at a tertiary referral centre in Sydney, Australia. We report novel clinical findings, including haemolysis and kidney rupture possibly related to immune reconstitution inflammatory syndrome. The positive effect of corticosteroids on haemodynamic function in two cases and the failure of currently recommended antimicrobial therapy to sterilise prosthetic valve material in the absence of surgery despite months of treatment are also critically examined. Positron emission tomography was positive in two cases despite normal transoesophageal echocardiograms. The proportion of cases with M. chimaera infection after aortic valve replacement (4/890, 0.45%; 95% confidence interval 0.18-1.15%) was significantly higher than after all other cardiothoracic surgical procedures (0/2433, 0%; 95% confidence interval 0-0.16%).

Disseminated Mycobacterium abscessus infection with spondylodiscitis of thoracic spine.

A case is presented of an immunosuppressed 51-year-old man with spondylodiscitis of the thoracic vertebrae from Mycobacterium abscessus infection, in context of disseminated multi-systemic infection with pulmonary and gastrointestinal involvement. Multiple challenges in the diagnosis and management of this confounding case are outlined. The patient underwent aggressive surgical debridement via T8-T10 vertebrectomy plus reconstruction, and right hemicolectomy to obtain source control. This was followed by prolonged combination antibiotic therapy. At time of manuscript patient is 10 months post-surgery and 18 months from initial presentation, with excellent surgical outcome and control of the infection. The unique microbiological and clinical characteristics of M. abscessus are briefly outlined. A synopsis of the relevant literature is given highlighting the relative paucity of evidence to aid management of this unpredictable infection. Current best practice guideline recommends combination of medical therapy and aggressive surgical debridement for infections caused by M. abscessus.

Improving influenza virus detection.

INTRODUCTION: Influenza virus infections cause significant morbidity, and the unique ability of these viruses to undergo antigenic drift and shift means that it is critical for current laboratory assays to keep pace with these changes for accurate diagnosis. New subtypes have the potential to evolve into pandemics hence accurate virus subtyping is also essential. AREAS COVERED: In this article, the authors review the current techniques available to detect influenza virus. EXPERT OPINION: The biggest gains in improving on influenza diagnostics may lie in reappraising our current approach and optimizing all existing steps in influenza detection: pre-analytical, analytical, post-analytical. In addition, we must foster close collaboration between governments, surveillance networks and frontline diagnostic laboratories, and utilize advances in information technology to facilitate these interactions and to disseminate crucial information.

Influenza A testing and detection in patients admitted through emergency departments in Sydney during winter 2009: implications for rational testing.

AIM: To examine factors associated with testing and detection of influenza A in patients admitted to hospital for acute care during the winter 2009 pandemic influenza outbreak. DESIGN, SETTING AND PARTICIPANTS: Retrospective observational study of patients who were tested for influenza A after being admitted to hospital through emergency departments of the Sydney South West Area Health Service from 15 June to 30 August 2009. MAIN OUTCOME MEASURES: The association of factors such as age, diagnosis at admission, hospital and week of admission with rates of testing and detection of influenza A. RESULTS: 17,681 patients were admitted through nine emergency departments; 1344 (7.6%) were tested for influenza A, of whom 356 (26.5%) tested positive for pandemic influenza. Testing rates were highest in 0-4-year-old children, in the peak period of the outbreak, and in patients presenting with a febrile or respiratory illness. Positive influenza test results were common across a range of diagnoses, but occurred most frequently in children aged 10-14 years (64.3%) and in patients with a diagnosis at admission of influenza-like illness (59.1%). Using multivariate logistic regression, patients with a diagnosis at admission of fever or a respiratory illness at admission were most likely to be tested (odds ratios [ORs], 15 [95% CI, 11-21] and 17 [95% CI, 15-19], respectively). These diagnoses were stronger predictors of influenza testing than the peak testing week (Week 4; OR, 7.0 [95% CI, 3.8-13]) or any age group. However, diagnosis at admission and age were significant but weak predictors of a positive test result, and the strongest predictor of a positive test result was the peak epidemic week (Week 3; OR, 120 [95% CI, 27-490]). CONCLUSION: The strongest predictor of a clinician's decision to test for influenza was the diagnosis at admission, but the strongest predictor of a positive test was the week of admission. A rational approach to influenza testing for patients who are admitted to hospital for acute care could include active tracking of influenza testing and detection rates, testing patients with a strong indication for antiviral treatment, and admitting only those who test negative to "clean" wards during the peak of an outbreak.