Carbapenem-resistant Enterobacteriaceae (CRE) are a pressing public health issue due to limited therapeutic options to treat such infections. CREs have been predominantly isolated from humans and ...environmental samples and they are rarely reported among companion animals. In this study we report on the isolation and plasmid characterization of carbapenemase (IMP-4) producing Salmonella enterica Typhimurium from a companion animal. Carbapenemase-producing S. enterica Typhimurium carrying bla
was identified from a systemically unwell (index) cat and three additional cats at an animal shelter. All isolates were identical and belonged to ST19. Genome sequencing revealed the acquisition of a multidrug-resistant IncHI2 plasmid (pIMP4-SEM1) that encoded resistance to nine antimicrobial classes including carbapenems and carried the bla
-qacG-aacA4-catB3 cassette array. The plasmid also encoded resistance to arsenic (MIC-150 mM). Comparative analysis revealed that the plasmid pIMP4-SEM1 showed greatest similarity to two bla
carrying IncHI2 plasmids from Enterobacter spp. isolated from humans in China. This is the first report of CRE carrying a bla
gene causing a clinical infection in a companion animal, with presumed nosocomial spread. This study illustrates the broader community risk entailed in escalating CRE transmission within a zoonotic species such as Salmonella, and in a cycle that encompasses humans, animals and the environment.
•Resistance to critically important antimicrobials registered in human medicine such as carbapenems was not detected.•Frequency of resistance was classified as low for FQN and moderate for 3GC among ...clinical E. coli from dogs.•Frequency of resistance was classified as low for both FQN and 3GC among clinical E. coli from cats.•Chronic disease and prior antimicrobial use were the main risk factors for the isolation of MDR E. coli from UTI.
Multidrug-resistant (MDR) Escherichia coli have become a major public health concern to both humans and animal health. While the frequency of antimicrobial resistance (AMR) in clinical E. coli is monitored regularly in human medicine, current frequency of AMR in companion animals remains unknown in Australia. In this study we conducted antimicrobial susceptibility testing (AST) and where possible, determined potential risk factors for MDR infection among 883 clinical Escherichia coli isolated from dogs (n=514), cats (n=341) and horses (n=28). AST was undertaken for 15 antimicrobial agents according to the Clinical Laboratory Standards Institute (CLSI) guidelines and interpreted using epidemiological cut-off values (ECOFFs) as well as CLSI veterinary and human clinical breakpoints. The AST revealed complete absence of resistance to carbapenems while resistance to amikacin was observed at a low level in isolates from dogs (1.6%) and cats (1.5%) compared to horses (10.7%). Among dog isolates, resistance to fluoroquinolones ranged from 9.1%–9.3% whereas among cat isolates, it ranged from 3.2%–5%. Among dog isolates, the proportion showing a 3rd generation cephalosporin (3GC) non-wild type phenotype was significantly higher (P<0.05) in skin and soft tissue infection (SSTI, n=122) isolates (17.2%–20.5%) compared to urinary tract infection (UTI, n=392) isolates (9.9%–10.2%). The frequency of multidrug resistance was 18.1%, 11.7% and 42.9% in dog, cat and horse isolates, respectively. Risk factor analysis revealed that MDR E. coli isolated from UTI were positively associated with chronicity of infection and previous antimicrobial treatment. Dogs and cats with chronic UTI that had been previously treated with antimicrobials were eight times and six times more likely to be infected with MDR E. coli compared to dogs and cats with non-chronic UTI, and no history of antimicrobial treatment, respectively. This study revealed that pre-existing disease condition and prior antimicrobial use were the major risks associated with UTI with MDR E. coli in companion animals.
This study aimed to determine the frequency and molecular epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) from Australian animals and whether animal-derived MRSA was similar to ...that from Australian veterinarians. A total of 1,080 clinical coagulase positive Staphylococcus isolates from Australian animals were collected during 2013. Sixteen (4%) of 360 S. aureus isolates were MRSA. Most MRSA came from companion animals, while none came from livestock. MRSA isolates were characterized using whole genome sequencing. ST22-IV (EMRSA-15) was the most common clone in dogs and cats. Clonal complex (CC) 8 was most common in horses. Most ST22-IV isolates were resistant to ciprofloxacin. Animal-derived MRSA genomes were interrogated for the presence of host-specific genetic markers (staphylokinase gene scn, chemotaxis-inhibiting proteins gene chp, staphylococcal complement inhibitor gene sak, enterotoxin A gene sea, and Von Willebrand Factor binding protein gene vwb). A subset of MRSA genomes previously collected from Australian veterinarians was also interrogated. There was no clear pattern in the distribution of host-specific markers among animal and veterinarian isolates. Animal- and veterinarian-derived MRSA were intermingled in the phylogenetic tree. The absence of MRSA in Australian livestock is in stark contrast with its presence in livestock from other countries. Possible explanations include Australia's geographic isolation, the absence of live animal importation into Australia, and most notably, the restrictions placed on the use of antimicrobials of critical importance in Australian livestock.
This study investigated the ecology, epidemiology and plasmid characteristics of extended-spectrum cephalosporin (ESC)-resistant E. coli in healthy pigs over a period of 4 years (2013-2016) following ...the withdrawal of ESCs. High carriage rates of ESC-resistant E. coli were demonstrated in 2013 (86.6%) and 2014 (83.3%), compared to 2015 (22%) and 2016 (8.5%). ESC resistance identified among E. coli isolates was attributed to the carriage of an IncI1 ST-3 plasmid (pCTXM1-MU2) encoding bla
. Genomic characterisation of selected E. coli isolates (n = 61) identified plasmid movement into multiple commensal E. coli (n = 22 STs). Major STs included ST10, ST5440, ST453, ST2514 and ST23. A subset of the isolates belong to the atypical enteropathogenic E. coli (aEPEC) pathotype that harboured multiple LEE pathogenic islands. pCTXM1-MU2 was similar (99% nt identity) to IncI1-ST3 plasmids reported from Europe, encoded resistance to aminoglycosides, sulphonamides and trimethoprim, and carried colicin Ib. pCTXM1-MU2 appears to be highly stable and readily transferable. This study demonstrates that ESC resistance may persist for a protracted period following removal of direct selection pressure, resulting in the emergence of ESC-resistance in both commensal E. coli and aEPEC isolates of potential significance to human and animal health.
We previously reported our phase Ib trial, testing the safety, tolerability, and efficacy of T-DM1 + neratinib in HER2-positive metastatic breast cancer patients. Patients with ERBB2 amplification in ...ctDNA had deeper and more durable responses. This study extends these observations with in-depth analysis of molecular markers and mechanisms of resistance in additional patients.
Forty-nine HER2-positive patients (determined locally) who progressed on-treatment with trastuzumab + pertuzumab were enrolled in this phase Ib/II study. Mutations and HER2 amplifications were assessed in ctDNA before (C1D1) and on-treatment (C2D1) with the Guardant360 assay. Archived tissue (TP0) and study entry biopsies (TP1) were assayed for whole transcriptome, HER2 copy number, and mutations, with Ampli-Seq, and centrally for HER2 with CLIA assays. Patient responses were assessed with RECIST v1.1, and Molecular Response with the Guardant360 Response algorithm.
The ORR in phase II was 7/22 (32%), which included all patients who had at least one dose of study therapy. In phase I, the ORR was 12/19 (63%), which included only patients who were considered evaluable, having received their first scan at 6 weeks. Central confirmation of HER2-positivity was found in 83% (30/36) of the TP0 samples. HER2-amplified ctDNA was found at C1D1 in 48% (20/42) of samples. Patients with ctHER2-amp versus non-amplified HER2 ctDNA determined in C1D1 ctDNA had a longer median progression-free survival (PFS): 480 days versus 60 days (P = 0.015). Molecular Response scores were significantly associated with both PFS (HR 0.28, 0.09-0.90, P = 0.033) and best response (P = 0.037). All five of the patients with ctHER2-amp at C1D1 who had undetectable ctDNA after study therapy had an objective response. Patients whose ctHER2-amp decreased on-treatment had better outcomes than patients whose ctHER2-amp remained unchanged. HER2 RNA levels show a correlation to HER2 CLIA IHC status and were significantly higher in patients with clinically documented responses compared to patients with progressive disease (P = 0.03).
The following biomarkers were associated with better outcomes for patients treated with T-DM1 + neratinib: (1) ctHER2-amp (C1D1) or in TP1; (2) Molecular Response scores; (3) loss of detectable ctDNA; (4) RNA levels of HER2; and (5) on-treatment loss of detectable ctHER2-amp. HER2 transcriptional and IHC/FISH status identify HER2-low cases (IHC 1+ or IHC 2+ and FISH negative) in these heavily anti-HER2 treated patients. Due to the small number of patients and samples in this study, the associations we have shown are for hypothesis generation only and remain to be validated in future studies. Clinical Trials registration NCT02236000.
The photoprotection and isolation of marinomycin A using sporopollenin exine capsules (SpECs) derived from the spores of the plant
Lycopodium clavatum
is described. The marinomycins have a ...particularly short half-life in natural light, which severely impacts their potential biological utility given that they display potent antibiotic and anticancer activity. The SpEC encapsulation of the marinomycin A
dramatically
increases the half-life of the polyene macrodiolide to the direct exposure to UV radiation by several orders of magnitude, thereby making this a potentially useful strategy for other light sensitive bioactive agents. In addition, we report that the SpECs can also be used to selectively extract culture broths that contain the marinomycins, which provides a significantly higher recovery than with conventional XAD resins and provides concomitant photoprotection.
Perfect partners for photoprotection: orally ingestible sporopollenin confers striking photoprotection to the powerful, polyene antibiotic, marinomycin A, as well as enabling its selective extraction.
•No MRSA was detected among bovine mastitis-associated Staphylococcus aureus isolates in Australia.•Over all low levels of antimicrobial resistance was detected. Resistance to only penicillin (12.4%) ...and erythromycin (0.5%) was identified among bovine mastitis-associated S. aureus isolates in Australia.•Most bovine mastitis-associated S. aureus belong to clonal complexes 97, 705, and 1.•Comparative genomic analysis revealed that Australian bovine S. aureus isolates clustering together according to their ST separately from human isolates.•S. aureus ST352 phylogeny provided evidence for geographical clustering of Australian strains into a distinct grouping separate from international bovine isolates.•Australian S. aureus isolates have limited genetic diversity and are genetically distinct from human and international bovine S. aureus isolates.
The aim of this study was to investigate antimicrobial resistance and population structure of bovine mastitis-associated Staphylococcus aureus isolates, and compare them to human isolates obtained from Western Australian hospitals and overseas strains to determine relatedness to human isolates from a zoonotic or reverse zoonotic aspect. Antimicrobial susceptibility testing was performed on 202 S. aureus isolates of which 166 isolates underwent whole genome sequencing. Only resistance to penicillin (12.4%) and erythromycin (0.5%) was identified and of note, no resistance was demonstrated to oxacillin. Genomic characterisation identified 14 multilocus sequence types (STs), with most isolates belonging to clonal complexes 97, 705, and 1. Four distinct clades based on virulence gene composition were identified. The four clades were predominantly ST based, consisting of ST352, ST97, ST81/ST1, and ST705. Core genome comparison of the bovine and human S. aureus isolates demonstrated defined clustering by ST, with the Australian bovine S. aureus isolates clustering together according to their ST separately from human isolates. In addition, a bovine specific cluster comprising Australian ST151 and ST705 isolates, and ST151 isolates from Irish dairy cattle was clearly delineated. Examination of a detailed ST352 phylogeny provided evidence for geographical clustering of Australian strains into a distinct grouping separate from international strains. This study has identified Australian S. aureus isolates have limited genetic diversity and are genetically distinct from human and international bovine S. aureus isolates. Current first line therapies for bovine mastitis in Australian dairy cattle remain appropriate.
With the rise in antimicrobial resistance, there is an urgent need for new classes of antibiotic with which to treat infectious disease. Marinomycin, a polyene antibiotic from a marine microbe, has ...been shown capable of killing methicillin-resistant
(MRSA) and vancomycin-resistant
(VREF), as well as having promising activity against melanoma. An attractive solution to the photoprotection of this antibiotic has been demonstrated. Here, we report the identification and analysis of the marinomycin biosynthetic gene cluster (BGC), and the biosynthetic assembly of the macrolide. The marinomycin BGC presents a challenge in heterologous expression due to its large size and high GC content, rendering the cluster prone to rearrangement. We demonstrate the transformation of
using a construct containing the cluster, and the heterologous expression of the encoded biosynthetic machinery and production of marinomycin B.
PDF
