Microbiological and Clinical Features of Patients with Cellulitis in Tropical Australia: Disease Severity Assessment and Implications for Clinical Management

Australian guidelines for the treatment of cellulitis are informed by data from temperate, metropolitan centers. It is uncertain if these guidelines are equally applicable in tropical Australia, where the population, access to healthcare, and array of potential pathogens are quite different. This retrospective study examined adults admitted to Cairns Hospital in tropical Queensland, Australia, who were treated with intravenous antibiotics for a principal diagnosis of cellulitis in 2019. The study aimed to describe the epidemiological, clinical, and microbiological findings in these cases and the resulting implications for patient management. There were 305 episodes of cellulitis; a potential pathogen was identified in 93/305 (30%), most commonly Staphylococcus aureus (45/93, 48%) or Group A Streptococcus (16/93, 17%). There was one case of Burkholderia pseudomallei. Initial treatment was most commonly with narrow spectrum β-lactam antibiotics with flucloxacillin prescribed in 170/305 (56%) and cefazolin prescribed in 74/305 (26%). Overall, 4/305 (1%) died or were admitted to the intensive care unit (ICU) within 30 days, 123/305 (40%) had an inpatient stay >48 hours, and 63/305 (21%) were readmitted to hospital within 30 days. Every patient who subsequently died or required ICU admission had an elevated early warning score (EWS ≥3) on admission. An EWS ≥3 on admission also predicted an inpatient stay of >48 hours (odds ratio [OR]: 3.2, 95% CI: 1.7-6.0; P <0.001) and 30-day readmission (OR: 2.3, 95% CI: 1.2-4.6; P = 0.01). The etiology of cellulitis in tropical Queensland, Australia, is very similar to that seen in temperate regions, enabling the use of standard management algorithms for patients with cellulitis in the region.