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Antimicrobial resistance (AMR) has emerged as a critical global health challenge. However, the significance of AMR is not limited to humans and domestic animals but extends to wildlife and the environment. Based on the analysis of > 200 peer-reviewed papers, this review provides comprehensive and current insights into the detection of clinically significant antimicrobial resistant bacteria and resistance genes in wild mammals, birds and reptiles worldwide. The review also examines the overlooked roles of wildlife in AMR emergence and transmission. In wildlife, AMR is potentially driven by anthropogenic activity, agricultural and environmental factors, and natural evolution. This review highlights the significance of AMR surveillance in wildlife, identifies species and geographical foci and gaps, and demonstrates the value of multifaceted One Health strategies if further escalation of AMR globally is to be curtailed., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Abstract: From 1 January 2020 to 31 December 2021, thirty-eight institutions across Australia submitted data to the Australian Group on Antimicrobial Resistance (AGAR) from patients aged < 18 years (AGAR-Kids). Over the two years, 1,679 isolates were reported from 1,611 patients. This AGAR-Kids report aims to describe the population of children and adolescents with bacteraemia reported to AGAR and the proportion of resistant isolates. Overall, there were 902 gram-negative isolates reported: 800 Enterobacterales , 61 Pseudomonas aeruginosa and 41 Acinetobacter spp. Among the Enterobacterales , 12.9% were resistant to third generation cephalosporins; 11.6% to gentamicin/tobramycin; and 11.2% to piperacillin-tazobactam. In total, 14.5% of Enterobacterales were multi-drug resistant (MDR). Only 3.3% of P. aeruginosa were resistant to carbapenems and 4.9% were MDR. Resistance in Acinetobacter spp was uncommon. Of 607 Staphylococcus aureus isolates, 12.9% were methicillin-resistant (MRSA). Almost half of S. aureus isolates from the Northern Territory were MRSA. In S. aureus , resistance to erythromycin was 13.2%; 12.4% to clindamycin; and 5.3% to ciprofloxacin. Resistance to all antibiotics tested was higher in MRSA. Overall, 6.5% of S. aureus were MDR, of which 65% were MRSA. Almost three-quarters of the 170 Enterococcus spp. reported were E. faecalis , and half were from patients < 1 year old. Ampicillin resistance in enterococci was 19.6%. Eight isolates were vancomycin resistant and three isolates were teicoplanin resistant. Five E. faecium isolates were classified as MDR. This AGAR-Kids report highlights clear differences in the geographic distribution of pathogens and resistance profiles across Australia., (© Commonwealth of Australia CC BY-NC-ND.)

Antimicrobial resistance (AMR) is a global pandemic, however, estimating its burden is a complex process. As a result, many countries rely on global estimates to infer burden within their own setting. With a growing number of recent publications quantifying AMR burden in Australia, and an expansion of surveillance programs, enumerating AMR mortality for Australia is feasible. We aimed to leverage existing published data to assess methodological factors contributing to the considerable variation in AMR-related mortality and provide two reliable estimates of AMR mortality in Australia. This is a necessary step towards generating meaningful measures of AMR burden in Australia.

SUMMARYEnterococci are a diverse group of Gram-positive bacteria that are typically found as commensals in humans, animals, and the environment. Occasionally, they may cause clinically relevant diseases such as endocarditis, septicemia, urinary tract infections, and wound infections. The majority of clinical infections in humans are caused by two species: Enterococcus faecium and Enterococcus faecalis . However, there is an increasing number of clinical infections caused by non- faecium non- faecalis (NFF) enterococci. Although NFF enterococcal species are often overlooked, studies have shown that they may harbor antimicrobial resistance (AMR) genes and virulence factors that are found in E. faecium and E. faecalis . In this review, we present an overview of the NFF enterococci with a particular focus on human clinical manifestations, epidemiology, virulence genes, and AMR genes., Competing Interests: The authors declare no conflict of interest.

Objectives: Daptomycin is one of the few last-line antimicrobials available for the treatment of multidrug-resistant Staphylococcus aureus infections. An increasing number of daptomycin non-susceptible S. aureus infections has been reported worldwide, including Australia. Resistance to daptomycin is multifactorial and involves chromosomal mutations in genes encoding proteins involved in cell membrane and cell wall synthesis., Methods: In this study, we performed broth microdilution (BMD) to determine the daptomycin minimum inhibitory concentration (MIC) of 66 clinical isolates of S. aureus previously reported as daptomycin non-susceptible by the VITEK Ⓡ 2. We used whole-genome sequencing to characterise the isolates and screened the genomes for mutations associated with daptomycin non-susceptibility., Results: Only 56 of the 66 isolates had a daptomycin MIC >1 mg/L by BMD. Although the 66 isolates were polyclonal, ST22 was the predominant sequence type and one-third of the isolates were multidrug resistant. Daptomycin non-susceptibility was primarily associated with MprF mutations-at least one MprF mutation was identified in the 66 isolates. Twelve previously reported MprF mutations associated with daptomycin non-susceptibility were identified in 83% of the isolates. Novel MprF mutations identified included P314A, P314F, P314T, S337T, L341V, F349del, and T423R., Conclusions: Daptomycin non-susceptible S. aureus causing infections in Australia are polyclonal and harbour MprF mutation(s). The identification of multidrug-resistant daptomycin non-susceptible S. aureus is a public health concern., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

The past decade has seen an increase in the prevalence of sequence type (ST) 45 methicillin-resistant Staphylococcus aureus (MRSA), yet the underlying drivers for its emergence and spread remain unclear. To better understand the worldwide dissemination of ST45 S. aureus, we performed phylogenetic analyses of Australian isolates, supplemented with a global population of ST45 S. aureus genomes. Our analyses revealed a distinct lineage of multidrug-resistant ST45 MRSA harbouring qacA, predominantly found in Australia and Singapore. Bayesian inference predicted that the acquisition of qacA occurred in the late 1990s. qacA was integrated into a structurally variable region of the chromosome containing Tn552 (carrying blaZ) and Tn4001 (carrying aac(6')-aph(2")) transposable elements. Using mutagenesis and in vitro assays, we provide phenotypic evidence that qacA confers tolerance to chlorhexidine. These findings collectively suggest both antimicrobial resistance and the carriage of qacA may play a role in the successful establishment of ST45 MRSA., (© 2024. The Author(s).)