Bacteraemia over 4 years in a Greater Western Sydney Metropolitan Local Health District: a retrospective descriptive study

Background

Bacteraemia is associated with significant morbidity and mortality. Understanding local patterns of bacteraemia including pathogen distribution, infection source, clinical speciality team burden, susceptibility data and mortality rates can inform empiric antibiotic choices, prevention approaches and education strategies.

Aims

To obtain descriptive data from positive blood cultures identified from Nepean Blue Mountains Local Health District in Greater Western Sydney.

Methods

A retrospective descriptive study was performed from August 2018 to March 2023 with data extracted from electronic medical records.

Results

A total of 6720 isolates were identified from positive blood cultures, of which 71.2% were clinically significant. The median age was 69 years. A total of 74.6% of clinically significant isolates were acquired in the community. The most commonly isolated pathogen was Escherichia coli (31.3%), followed by Staphylococcus aureus (14.3%), and 8.6% of patients with clinically significant positive blood cultures were neutropenic. Neutropenic patients were more likely to have Pseudomonas aeruginosa as the causative pathogen (11.4%) compared to the entire study population (3.9%). The most commonly identified source of infection was the urinary tract. The 30-day all-cause mortality rate for clinically significant positive blood cultures was 16.8%, with higher mortality rates seen with Candida species (and species previously known as Candida), P. aeruginosa and Enterococcus species. 94% of bacteraemia from Enterobacterales tested susceptible in vitro to ampicillin and/or gentamicin. The rate of methicillin resistance in S. aureus was 24%.

Conclusions

This study provides valuable insight into the local epidemiology of bacteraemia, which will allow for targeted prevention, management and educational strategies to improve outcomes.