Antibiotic resistance

Event Date: 
Wednesday, February 25, 2015 - 17:30 - 18:00
Institution: 
University of Melbourne
Title: 

Genomic epidemiology of antibiotic resistant bacteria

Abstract: 

Microbial populations contribute to human disease in a variety of ways, both as agents of infection and as healthy components of the microbiome. Genomic approaches can offer deep insights into this hidden microbial world, including revealing the composition of microbial communities, tracking the movement of individual organisms, and illuminating evolutionary changes. Here I will present recent work applying genomic epidemiology to investigate the emergence and spread of antibiotic resistance in a range of important pathogens, including typhoid, dysentery and the emerging hospital superbug Klebsiella.

Event Date: 
Wednesday, October 29, 2014 - 19:00 - 19:30
Institution: 
UTS
Title: 

“On the value of reframing antibiotic resistance as a disaster risk problem”

Abstract: 

Dr. Maurizio Labbate1,2 & A/Prof. Dale Dominey-Howes3

1School of Medical and Molecular Biosciences, University of Technology, Sydney, Australia.
2The ithree Institute, University of Technology, Sydney, Australia.
3Asia – Pacific Natural Hazards Research Group, School of Geosciences, University of Sydney, Australia.

Abstract:

On the 1st May 2014 the World Health Organization in its first global assessment of antimicrobial resistance reported that antibiotic resistance has now reached alarming proportions and is no longer a future problem but a contemporary reality. This comes off the back of other urgent calls from leading authorities including the Deputy Director of the Center for Disease Control (CDC) who has publicly stated that we have now reached the “end of the antibiotic era” and the UK Chief Medical Officer, Professor Dame Sally Davies who called for antibiotic resistance to be placed on the risk register above the issue of terrorism. Increasingly, the tone of the language used by these organizations and individuals is reminiscent of that used by the disaster and emergency risk management communities to describe commonly occurring disasters such as earthquakes, fires, floods and storms.

Antibiotic resistant infections are rising fast and affect millions of people globally. Antibiotic resistance has become a slow onset disaster that like climate change has struggled to elicit the sort of coordinated international response that is required to deal with the magnitude of the emergency. Anthropogenic modification of the Earth’s climate system provides the foundation for sudden onset natural disasters such as hurricanes, wildfires and storms. Likewise, increasingly widespread antibiotic resistance is laying the foundation for the future occurrence of sudden onset bacterial epidemic and pandemic disasters.

Despite the finest efforts by medical and health policy makers and communities to control the antibiotic resistance problem, the issue has reached a critical tipping point. Given the current state of the antibiotic resistance problem and the likely near future of untreatable bacterial infections, we propose an alternative and novel policy perspective. With this is mind, we propose to make antibiotic a broader issue and reframe it as a disaster risk problem and engage the expertise of emergency managers. Governments and disaster policy makers across the world use the Emergency Risk Management process in the management of and preparation for natural disasters. This process is a systematic method that through engagement with multiple stakeholders identifies, analyses, evaluates and treats risks and takes an iterative approach with well-defined activities that lead to implementation of risk-treatment strategies tailored to a specific community’s risk profile. This policy and practice framework is an excellent mechanism for reaching out to communities and communicating complex messages – an area that needs to be enhanced.

Event Date: 
Wednesday, August 27, 2014 - 19:00 - 20:00
Institution: 
Macquarie University
Title: 

"Xenbiotics and Xenogenetics: Human Influence over Microbial Evolution"

Abstract: 

The extent of human effects on planetary and biological processes means that we are now the world’s greatest evolutionary force. Perhaps the best example of human driven selection is the rapid evolution of antibiotic resistance in a wide range of bacterial pathogens. Continued antibiotic use has resulted in the assembly of complex DNA molecules composed of diverse resistance determinants and mobile elements, each with independent phylogenetic origins. These novel plasmids, transposons, integrons and genomic islands are xenogenetic, in that they have arisen in human-dominated ecosystems as a direct result of human activity. Xenogenetic elements are being released via human waste streams along with significant quantities of selective agents and other xenobiotic compounds, creating environmental reactors that foster even more complex interactions between genes, mobile elements and diverse bacterial species. Saturation of the environment with selective agents is also likely to increase the basal rates of mutation, recombination and lateral gene transfer in all bacterial species. Consequently, the antibiotic revolution may now be having unintended, second order consequences that will affect the entire microbial biosphere.

Event Date: 
Wednesday, August 27, 2014 - 18:00 - 18:15
Institution: 
USyd
Title: 

Bowel movement: resistance plasmid transfer in the gut

Abstract: 

The treatment of endogenous infections caused by commensal Escherichia coli are often complicated by antibiotic resistance. Strains of resistant E. coli in the gastrointestinal tract serve as a reservoir of resistance determinants, and dissemination of resistance genes is often facilitated by conjugative plasmids. It is important to understand these plasmids in order to track the movement of resistance determinants between populations.
 
Three faecal E. coli isolates from a healthy adult were examined. Two of these (838-98B and -3B) were resistant to ampicillin (Ap), streptomycin (Sm) and sulphamethoxazole (Su). The other (838-50A) was susceptible. 838-50A and -3B were indistinguishable by biochemical and molecular analysis (API20E, phylogenetic group PCR, RAPD). 838-98B was a distinct strain. B/O plasmid replicons were detected in both resistant isolates using PCR-based plasmid replicon typing. A B/O replicon was not detected in the susceptible strain. This suggested that a plasmid bearing a B/O replicon might be responsible for ApSmSu resistance. Conjugation experiments with a laboratory adapted E. coli strain (UB5201) confirmed that the movement of a B/O plasmid from both 838-98B and -3B conferred ApSmSu resistance. Plasmid sequencing revealed that an identical B/O plasmid, p838B-R (94.8kb), was present in 838-98B and -3B, and carried ApSmSu resistance determinants. p838B-R was also observed to mobilise small plasmids, allowing the direction of in situ transfer to be determined.
 
The observed transfer of antibiotic resistance plasmid p838B-R between two unrelated strains in the gastrointestinal tract highlights the important role commensal bacteria play in the spread of resistance determinants. While not well documented, the association of B/O-type plasmids with antibiotic resistance is evident not only through p838B-R but also other available plasmid sequences. Further studies will allow us to determine the extent to which these plasmids influence antibiotic resistance in commensal E. coli

Event Date: 
Wednesday, May 29, 2013 - 18:15 - 18:30
Institution: 
Macquarie University
Title: 

Dissemination of antibiotic resistance determinants via sewage discharge from Davis Station, Antarctica

Abstract: 

Discharge of untreated or macerated sewage presents a significant risk to Antarctic marine ecosystems by introducing non-native microorganisms that potentially impact microbial communities and threaten health of Antarctic wildlife. Despite these risks, disposal of essentially untreated sewage continues in the Antarctic and sub-Antarctic. As part of an environmental impact assessment of the Davis Station, we investigated carriage of antibiotic resistance determinants in Escherichia coli isolates from marine water and sediments, marine invertebrates (Laturnula and Abatus), birds and mammals within 10 km of the Davis sewage outfall. Class 1 integrons typical of human pathogens and commensals were detected in 12% of E. coli isolates. E. coli carrying these integrons were primarily isolated from the near shore marine water column and the filter feeding mollusc Laturnula. Class 1 integrons were not detected in E. coli isolated from seal (Miroungaleonina, Leptonychotes weddellii) or penguin (Pygoscelis adeliae) feces. However, isolation of E. coli from these vertebrates’ faeces was also low. Consequently, sewage disposal is introducing non-native microorganisms and associated resistance genes into the Antarctic environment. The impact of this “gene pollution” on the diversity and evolution of native Antarctic microbial communities is unknown. 

 

Event Date: 
Wednesday, February 27, 2013 - 18:00 - 18:30
Institution: 
University of Sydney
Title: 

A tale of two clones; multiple antibiotic resistance in Acinetobacter baumannii .

Abstract: 

The importance of Acinetobacter baumannii in causing nosocomial infections was only recognised in the mid 1980s, making it the least studied of the bacteria that are now resistant to most of the antibiotics that are most important for treatment of such infections. We assembled a large collection of A. baumannii isolates recovered between 1999 and 2011 at hospitals in Sydney, Canberra, Brisbane, Melbourne, Newcastle and Adelaide. All but a few of those that are resistant to multiple antibiotics belong to one of two clonal groups that have recently been found to be globally distributed. Hence, these clones, global clone 1 and 2, have been in Australia at least since the mid 1990s.
Representatives of hospitals and of groups with different carbapenem and aminoglycoside resistance patterns in our collection have been sequenced together with the GC1 and GC2 reference strains from the early 1980s. Trees based on single nucleotide polymorphisms reveal significant diversity in the Australian isolates from one clone and little in the other. Most of the genes conferring resistance to older antibiotics are in the chromosome clustered in one island in GC1 and two in GC2 isolates. However, each of these islands is continually evolving, losing and gaining resistance genes. Further variation arises from the acquisition of different plasmids carrying further resistance genes. Other major but unexpected differences arising within the clones affect the exopolysaccharides. The capsule is an important virulence determinant, and substitution of large chromosomal segments leads to many distinct loci for capsule biosynthesis in each clone.

Event Date: 
Wednesday, November 24, 2010 - 18:15 - 18:30
Institution: 
USyd
Title: 

Active partitioning by S. aureus conjugative multiresistance plasmids.

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