Clinical characteristics and outcomes of COVID-19 in a low-prevalence, well resourced setting, Sydney, Australia.

BACKGROUND: The Northern Sydney Local Health District was one of the first health regions to be affected by COVID-19 in Australia. AIMS: To describe the clinical characteristics, risk factors and outcomes in our low-prevalence Australian population. METHODS: This is a retrospective analysis of 517 laboratory-confirmed COVID-19 cases between January and June 2020. Patient information was collected as part of routine care within the COVID-19 Virtual Hospital system. Outcomes examined were death, recovery at 30 days and intensive care unit (ICU) admission. RESULTS: The case fatality rate was 1.8%. Multivariate analysis showed factors independently associated with death, composite outcome of death/ICU admission or incomplete recovery at 30 days were age >80 years and presence of two or more comorbidities. Most cases acquired COVID-19 through international (50.9%) or cruise ship travel (9.1%). Healthcare workers comprised 12.8% of the cohort and represented a disproportionately high percentage of the 'unknown' source group (27.6%). The median incubation period was 5 days (interquartile range 3-8); one patient had an incubation period of 15 days. Hospitalisation was required in 11.8%, ICU admission in 2.1% and ventilation in 1.4%. A Radiographic Assessment of Lung Oedema score on chest X-ray of >10 was independently associated with death. CONCLUSIONS: In this low prevalence, well resourced Australian setting, we report an overall low mortality. Factors associated with adverse patient outcomes on multivariate analysis were age greater than 80 and the presence of two or more comorbidities. These data can assist in early risk stratification of COVID-19 patients, and in surge capacity planning for hospitals.

Sonication versus Tissue Sampling for Diagnosis of Prosthetic Joint and Other Orthopedic Device-Related Infections.

Current guidelines recommend collection of multiple tissue samples for diagnosis of prosthetic joint infections (PJI). Sonication of explanted devices has been proposed as a potentially simpler alternative; however, reported microbiological yield varies. We evaluated sonication for diagnosis of PJI and other orthopedic device-related infections (DRI) at the Oxford Bone Infection Unit between October 2012 and August 2016. We compared the performance of paired tissue and sonication cultures against a "gold standard" of published clinical and composite clinical and microbiological definitions of infection. We analyzed explanted devices and a median of five tissue specimens from 505 procedures. Among clinically infected cases the sensitivity of tissue and sonication culture was 69% (95% confidence interval, 63 to 75) and 57% (50 to 63), respectively (P < 0.0001). Tissue culture was more sensitive than sonication for both PJI and other DRI, irrespective of the infection definition used. Tissue culture yield was higher for all subgroups except less virulent infections, among which tissue and sonication culture yield were similar. The combined sensitivity of tissue and sonication culture was 76% (70 to 81) and increased with the number of tissue specimens obtained. Tissue culture specificity was 97% (94 to 99), compared with 94% (90 to 97) for sonication (P = 0.052) and 93% (89 to 96) for the two methods combined. Tissue culture is more sensitive and may be more specific than sonication for diagnosis of orthopedic DRI in our setting. Variable methodology and case mix may explain reported differences between centers in the relative yield of tissue and sonication culture. Culture yield was highest for both methods combined.

Q fever cholecystitis in an unvaccinated butcher diagnosed by gallbladder polymerase chain reaction.

Acalculous cholecystitis has been described in association with Q fever. We describe the first known case of Q fever cholecystitis diagnosed by polymerase chain reaction on gallbladder tissue. The presence of Coxiella burnetii genome in the diseased gallbladder tissue argues for direct involvement of the organism in the pathogenesis of Q fever cholecystitis.