The National Alert System for Critical Antimicrobial Resistances (CARAlert) is a program monitoring trends in priority pathogens with critical resistances to last-line antimicrobial agents, allowing early recognition and communication of critical antimicrobial resistances to all jurisdictions across Australia.
According to the latest data published in May 2024, 2,686 critical antimicrobial resistances (CARs) were reported by 72 laboratories across Australia in 2023, an 86 per cent increase compared to 2022.
Most cases came from the most populous states, primarily from Victoria (41 per cent), followed by NSW (36 per cent) and Queensland (11 per cent). The majority were detected in hospitals (62 per cent), with a smaller proportion identified in community settings (38 per cent) and a minimal number in aged care homes (0.4 per cent).
The trends observed in national surveillance of bacteria with critical antibiotic resistance are very concerning. In Victoria, there is a notable increase in detections of these bacteria, highlighting the urgent need for more robust prevention activities in all sectors.
Key findings
Carbapenemase-producing Enterobacterales (CPE)
CPE are a family of bacteria that normally live harmlessly in our bowel, like E. coli. They are among the top antibiotic-resistant threats worldwide making CPE infections challenging to treat because of limited antibiotic options.
- In 2023, CPE was the most frequently reported bacteria with CAR (45 per cent).
- Almost three-quarters of CPE were found in people aged 50 years and older.
- Concerningly, the total number of CPE reported in Australia has increased by over 45 per cent since 2021, after a decline from 2019 to 2021. In particular, CPE reports increased by 78 per cent in Victoria with variation between the different types of CPE. In Victoria, fewer CPE were identified incidentally through screening of asymptomatic individuals and mostly detected in people with clinical infections.
Pseudomonas aeruginosa
A major cause of healthcare-associated infections worldwide, P. aeruginosa can cause different types of infection and has become increasingly resistant to antibiotics, making treatment challenging.
- In 2023, 75 instances of critically resistant P. aeruginosa were reported in five states, with the majority in NSW (44 per cent).
- One of the subtypes of highly drug-resistant P. aeruginosa was mostly reported in Victoria (45 per cent).
Enterococcus species
Enterococcus spp. are a group of bacteria that can be antibiotic-resistant. Typically part of the normal gut flora, they can cause serious infections if they travel to other parts of the body.
- In 2023, 39 cases of linezolid-resistant Enterococcus spp., a strain resistant to a last-resort antibiotic linezolid, were reported across all jurisdictions except Tasmania, more than double what was detected in 2022.
- Reports of linezolid-resistant Enterococcus species increased five-fold in Victoria between 2022 and 2023, after no reports in 2021. Of concern also is the increased antimicrobial resistance reported in both E. faecium and E. faecalis.
Candida auris
Candida auris, an emerging highly-resistant Candida species, is associated with international outbreaks of invasive fungal infections in healthcare settings, posing challenges in treatment due to its multi-drug resistance.
- There were 17 reports of C. auris in Australia in 2023 compared to 9 reports in 2022, with two reports from Victoria.
Shigella species
Shigella bacteria are responsible for intestinal infections which can lead to serious complications in people with weaker immune systems. These infections may be acquired via food and water during overseas travel, but they may also be spread among men who have sex with men.
- In 2023, there were 469 reports of multidrug-resistant Shigella species, marking a significant tenfold increase compared to 2021. The majority of these reports originated from Victoria and NSW.
- COVID-19 restrictions initially reduced case numbers, but reports surged as borders reopened, indicating ongoing challenges in curbing transmission.
- Antibiotic-resistant Shigella sonnei was the predominant species reported, comprising over 72% of cases.