Verification of the IDI-MRSA assay for detecting methicillin-resistant Staphylococcus aureus in diverse specimen types in a core clinical laboratory setting.

The IDI-MRSA assay has a sensitivity of 96% and a specificity of 96% when used to screen patients at extranasal sites. This verification study used previously unverified swabs and was undertaken in a core medical laboratory using nonmicrobiology technologists trained in sample processing, molecular laboratory work flow, and PCR practice.

Risk of ruling out severe acute respiratory syndrome by ruling in another diagnosis: variable incidence of atypical bacteria coinfection based on diagnostic assays.

BACKGROUND: Severe acute respiratory syndrome (SARS) caused the first epidemic of the 21st century and continues to threaten the global community. OBJECTIVE: To assess the incidence of coinfection in patients confirmed to have SARS-associated coronavirus (SARS-CoV) infection, and thus, to determine the risk of ruling out SARS by ruling in another diagnosis. METHODS: The present report is a retrospective study evaluating the incidence and impact of laboratory-confirmed SARS-CoV and other pulmonary pathogens in 117 patients. These patients were evaluated in a Toronto, Ontario, community hospital identified as the epicentre for the second SARS outbreak. RESULTS: Coinfection with other pulmonary pathogens occurred in patients with SARS. Seventy-three per cent of the patient population evaluated had laboratory-confirmed SARS-CoV infection. Serology showing acute or recent Chlamydophila pneumoniae or Mycoplasma pneumoniae infection revealed an incidence of 30% and 9%, respectively, in those with SARS. These rates are similar to previously published studies on coinfection in pneumonia. All nucleic acid diagnostic assays were negative for C pneumoniae and M pneumoniae in respiratory samples from patients with SARS having serological evidence for these atypical pathogens. CONCLUSIONS: Diagnostic assays for well-recognized pulmonary pathogens have limitations, and ruling out SARS-CoV by ruling in another pulmonary pathogen carries significant risk. Despite positive serology for atypical pathogens, in a setting where clinical suspicion for SARS is high, specific tests for SARS should be performed to confirm or exclude a diagnosis.

Dynamic changes in clinical features and cytokine/chemokine responses in SARS patients treated with interferon alfacon-1 plus corticosteroids.

Severe acute respiratory syndrome (SARS), caused by a novel coronavirus, emerged in early 2003 as a major international health crisis. We report on serum cytokine levels, viral load and clinical parameters over the course of the disease in a cohort of nine adult SARS patients treated with steroids and interferon alfacon-1 at North York General Hospital in Toronto, Ontario. Considerable variation among SARS patients with respect to circulating viral load and patterns of SARS-CoV-evoked cytokine responses was recorded. No single cytokine profile was observed in all patients, yet serum concentrations of interferon (IFN)-gamma, interleukin (IL)-10, CXCL10, CCL5 and CXCL8 were found to be elevated above normal levels during the course of the disease in all patients. Expression levels for IL-10, IFN-gamma and CXCL10 consistently peaked within 4 days of peak viral load. IL-12p70, IL-4 and tumour necrosis factor-alpha concentrations were consistently highest within 5 days of peak viral load. These results suggest that elevated levels of inflammatory cytokines are sensitive correlates of disease severity, including lung abnormalities and viral load in serum, and may provide a tool for monitoring disease progression in affected individuals.

Interferon alfacon-1 plus corticosteroids in severe acute respiratory syndrome: a preliminary study.

CONTEXT: Severe acute respiratory syndrome (SARS) is a new clinical entity for which no effective therapeutic strategy has been developed. OBJECTIVE: To provide preliminary results on the potential therapeutic benefit and tolerability of interferon alfacon-1 plus corticosteroids for SARS. DESIGN, SETTING, AND PATIENTS: Open-label study of 22 patients diagnosed as having probable SARS at North York General Hospital, Toronto, Ontario, between April 11 and May 30, 2003. INTERVENTIONS: Thirteen patients were treated with corticosteroids alone and 9 patients were treated with corticosteroids plus subcutaneous interferon alfacon-1. MAIN OUTCOME MEASURES: Clinical parameters, including oxygen saturation and requirement, laboratory measures, and serial chest radiography results. RESULTS: Resolution of fever and lymphopenia were similar between the 2 treatment groups. Of the 13 patients treated with corticosteroids alone, 5 (38.5%) were transferred to the intensive care unit, 3 (23.1%) required intubation and mechanical ventilation, and 1 (7.7%) died. Of the 9 patients in the interferon alfacon-1 treatment group, 3 (33.3%) were transferred to the intensive care unit, 1 (11.1%) required intubation and mechanical ventilation, and none died. The interferon alfacon-1 treatment group had a shorter time to 50% resolution of lung radiographic abnormalities (median time, 4 days vs 9 days; P =.001), had better oxygen saturation (P =.02), resolved their need for supplemental oxygen more rapidly (median, 10 days vs 16 days; P =.02), had less of an increase in creatine kinase levels (P =.03), and showed a trend toward more rapid resolution of lactate dehydrogenase levels compared with the group receiving corticosteroids alone. CONCLUSIONS: In this preliminary, uncontrolled study of patients with SARS, use of interferon alfacon-1 plus corticosteroids was associated with reduced disease-associated impaired oxygen saturation, more rapid resolution of radiographic lung abnormalities, and lower levels of creatine kinase. These findings suggest that further investigation may be warranted to determine the role of interferon alfacon-1 as a therapeutic agent for the treatment of SARS.