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1.  High Metabolic Potential May Contribute to the Success of ST131 Uropathogenic Escherichia coli 
Journal of Clinical Microbiology  2012;50(10):3202-3207.
Uropathogenic Escherichia coli (UPEC) is the predominant cause of urinary tract infection in both hospital and community settings. The recent emergence of multidrug-resistant clones like the O25b:H4-ST131 lineage represents a significant threat to health, and numerous studies have explored the virulence potential of these organisms. Members of the ST131 clone have been described as having variable carriage of key virulence factors, and it has been suggested that additional unidentified factors contribute to virulence. Here we demonstrated that ST131 isolates have high metabolic potential and biochemical profiles that distinguish them from isolates of many other sequence types (STs). A collection of 300 UPEC isolates recovered in 2007 and 2009 in the Northwest region of England were subjected to metabolic profiling using the Vitek2 Advanced Expert System (AES). Of the 47 tests carried out, 30 gave a positive result with at least one of the 300 isolates examined. ST131 isolates demonstrated significant association with eight tests, including those for peptidase, decarboxylase, and alkalinization activity. Metabolic activity also correlated with antibiotic susceptibility profiles, with resistant organisms displaying the highest metabolic potential. This is the first comprehensive study of metabolic potential in the ST131 lineage, and we suggest that high metabolic potential may have contributed to the fitness of members of the ST131 clone, which are able to exploit the available nutrients in both the intestinal and urinary tract environments.
doi:10.1128/JCM.01423-12
PMCID: PMC3457456  PMID: 22814460
2.  Multi-resistant Escherichia coli and mycotic aneurysm: two case reports 
Introduction
Mycotic aneurysms account for a small proportion of all aneurysms. Escherichia coli a gram-negative organism, is recognised as a rare cause of aortic aneurysm. We report two cases of mycotic aneurysm caused by the same strain of multi-resistant Escherichia coli. The purpose of this case report is to highlight the possibility that this strain may be associated with an increased risk of endovascular infection especially in extra-aortic sites. These aneurysms can be difficult to detect and can have serious consequences.
Case presentation
In case one, the patient presented with symptoms and signs of septicaemia secondary to a urinary tract infection. Despite adequate treatment the patient continued with pyrexia and raised inflammatory markers, therefore a series of CT scans of the abdomen and thorax were performed, which revealed two intra-thoracic pseudo-aneurysms with associated haematomas. In case two, the patient also developed Escherichia coli septicaemia. On day 44 he developed a swelling on the right side of his neck. An ultrasound scan showed a pseudoaneurysm of the right common carotid artery.
Conclusions
Whilst a case report cannot prove that a heightened risk exists, we suggest that it is an area worthy of further surveillance. We recommend when older patients with atheromatosis develop prolonged Escherichia coli septicaemia, the possibility of an infected aneurysm should be borne in mind.
doi:10.1186/1752-1947-3-6453
PMCID: PMC2726478  PMID: 19830106
3.  Rapid Evolution and the Importance of Recombination to the Gastroenteric Pathogen Campylobacter jejuni 
Molecular Biology and Evolution  2008;26(2):385-397.
Responsible for the majority of bacterial gastroenteritis in the developed world, Campylobacter jejuni is a pervasive pathogen of humans and animals, but its evolution is obscure. In this paper, we exploit contemporary genetic diversity and empirical evidence to piece together the evolutionary history of C. jejuni and quantify its evolutionary potential. Our combined population genetics–phylogenetics approach reveals a surprising picture. Campylobacter jejuni is a rapidly evolving species, subject to intense purifying selection that purges 60% of novel variation, but possessing a massive evolutionary potential. The low mutation rate is offset by a large effective population size so that a mutation at any site can occur somewhere in the population within the space of a week. Recombination has a fundamental role, generating diversity at twice the rate of de novo mutation, and facilitating gene flow between C. jejuni and its sister species Campylobacter coli. We attempt to calibrate the rate of molecular evolution in C. jejuni based solely on within-species variation. The rates we obtain are up to 1,000 times faster than conventional estimates, placing the C. jejuni–C. coli split at the time of the Neolithic revolution. We weigh the plausibility of such recent bacterial evolution against alternative explanations and discuss the evidence required to settle the issue.
doi:10.1093/molbev/msn264
PMCID: PMC2639114  PMID: 19008526
Campylobacter jejuni; molecular clock; recombination; selection; coalescent; Neolithic
4.  Tracing the Source of Campylobacteriosis 
PLoS Genetics  2008;4(9):e1000203.
Campylobacter jejuni is the leading cause of bacterial gastro-enteritis in the developed world. It is thought to infect 2–3 million people a year in the US alone, at a cost to the economy in excess of US $4 billion. C. jejuni is a widespread zoonotic pathogen that is carried by animals farmed for meat and poultry. A connection with contaminated food is recognized, but C. jejuni is also commonly found in wild animals and water sources. Phylogenetic studies have suggested that genotypes pathogenic to humans bear greatest resemblance to non-livestock isolates. Moreover, seasonal variation in campylobacteriosis bears the hallmarks of water-borne disease, and certain outbreaks have been attributed to contamination of drinking water. As a result, the relative importance of these reservoirs to human disease is controversial. We use multilocus sequence typing to genotype 1,231 cases of C. jejuni isolated from patients in Lancashire, England. By modeling the DNA sequence evolution and zoonotic transmission of C. jejuni between host species and the environment, we assign human cases probabilistically to source populations. Our novel population genetics approach reveals that the vast majority (97%) of sporadic disease can be attributed to animals farmed for meat and poultry. Chicken and cattle are the principal sources of C. jejuni pathogenic to humans, whereas wild animal and environmental sources are responsible for just 3% of disease. Our results imply that the primary transmission route is through the food chain, and suggest that incidence could be dramatically reduced by enhanced on-farm biosecurity or preventing food-borne transmission.
Author Summary
C. jejuni is a bacterium commonly found in the guts of birds and mammals. In humans, it is responsible for causing more gastro-enteritis than any other identified bacterial species. Humans may contract campylobacter from a variety of sources. Eating raw or undercooked meat or poultry, and poor food hygiene that leads to cross-contamination of uncooked food, can cause human disease. However, humans may be exposed to the feces of infected wild animals, and campylobacter can survive in water. Contamination of drinking water can lead to outbreaks, and previous genetic studies have suggested that livestock are not the principal source of human infection. We extracted campylobacter DNA from patients and compared it to campylobacter DNA found in livestock, wild animals, and the environment. We developed a new evolutionary model to identify the most probable source populations. In 97% of cases, we identified chicken, cattle, or sheep as the source of infection. Very few cases were attributable to campylobacter found in wild animals or the environment. Our results imply that the primary transmission route is the food chain and also add new impetus to measures that reduce infection in livestock and prevent food-borne transmission.
doi:10.1371/journal.pgen.1000203
PMCID: PMC2538567  PMID: 18818764
5.  Major Uropathogenic Escherichia coli Strain Isolated in the Northwest of England Identified by Multilocus Sequence Typing▿  
Journal of Clinical Microbiology  2008;46(3):1076-1080.
A total of 88 uropathogenic Escherichia coli isolates, including 68 isolates from urine and 20 isolates from blood, were characterized by multilocus sequence typing (MLST). MLST has identified an important genetic lineage of E. coli, designated sequence type 131 (ST-131), represented by 52 of these isolates, 51 of which were resistant to extended-spectrum cephalosporins. ST-131 appears to be a drug-resistant uropathogenic strain of E. coli responsible for causing urinary tract infections and bacteremia and is widely disseminated among both community and hospital patients from different geographical areas in the northwest of England. Application of MLST has helped to define the population biology which may underpin the epidemiology of pathogenic E. coli strains. The portability of MLST allows the accurate monitoring of this antibiotic-resistant uropathogenic strain of E. coli and will enhance surveillance for this important group of organisms.
doi:10.1128/JCM.02065-07
PMCID: PMC2268376  PMID: 18199778

Results 1-6 (6)