Domestic shower hose biofilms contain fungal species capable of causing opportunistic infection

The domestic environment can be a source of pathogenic bacteria. We show here that domestic shower hoses may harbour potentially pathogenic bacteria and fungi. Well-developed biofilms were physically removed from the internal surface of shower hoses collected in four locations in England and Scotland. Amplicon pyrosequencing of 16S and 18S rRNA targets revealed the presence of common aquatic and environmental bacteria, including members of the Actinobacteria, Alphaproteobacteria, Bacteroidetes and non-tuberculous Mycobacteria. These bacteria are associated with infections in immunocompromised hosts and are widely reported in shower systems and as causes of water-acquired infection. More importantly, this study represents the first detailed analysis of fungal populations in shower systems and revealed the presence of sequences related to Exophiala mesophila, Fusarium fujikuroi and Malassezia restricta. These organisms can be associated with the environment and healthy skin, but also with infection in compromised and immuno-competent hosts and occurrence of dandruff. Domestic showering may result in exposure to aerosols of bacteria and fungi that are potentially pathogenic and toxigenic. It may be prudent to limit development of these biofilms by the use of disinfectants, or regular replacement of hoses, where immuno-compromised persons are present

The fractional integrated bi- parameter smooth transition autoregressive model

This paper introduces the fractionally integrated Bi-parameter smooth transition autoregressive model (FI-BSTAR model) as an extension of BSTAR model proposed by Siliverstovs (2005) and the fractionally integrated STAR model (FI-STAR model) proposed by van Dijk et al. (2002). Our FI-BSTAR model is able to simultaneously describe persistence and asymmetric smooth structural change in time series. An empirical application using monthly growth rates of the American producer price index is provided.Long Memory, Nonlinearity, Asymmetry, STAR models.

Molecular epidemiology of uropathogenic Escherichia coli in North West England and characterisation of the ST131 clone in the region

Multilocus Sequence-Typing (MLST) is a phylogenetic technique based on the detection of differences in multiple conserved housekeeping genes. Together with powerful evaluation software, MLST provides an extensive classification scheme for highly diverse species. However, despite the increasing use of MLST as a trusted epidemiological tool, the population structure of UPEC has been poorly studied using this technique, as most of the previous studies conducted have been limited either by bias towards certain characteristics, such as antimicrobial resistance and serogroup, or included a limited number of strains. Such studies can give a false impression of the population structure due to overrepresentation of certain Sequence types (STs).In this thesis, MLST was applied to 300 E. coli isolates collected from in the North West of England between June 2007 and June 2009. Firstly, the prevalence, diversity, epidemiological relationships and phylogenetic origins of the identified STs were determined. Secondly, possible associations of key UPEC STs with other genotypic and phenotypic profiles were assessed. Thirdly, as ST131 was recently reported as one of the most successful UPEC clones, an extensive examination of isolates of this clone was carried out involving identification of multiple drug resistant subclones and attempts were made to recognise putative predictor markers for identification of the ST131 clone.MLST analysis of the studied population revealed a consistent profile of STs that occurred repeatedly in the collection. It consisted primarily of ST73 (16%) followed by ST131 (13.3%), ST69 (9%), ST95 (6.3%), ST10 (4.3%), ST127 (3.6%), ST14 (2.6%) and ST405 (1.6%) some of the STs (ST127 and ST80) in the panel have never been reported as remarkable uropathogens.The broad range of virulence factor (VF) genes screened here allowed the recognition of VF patterns significantly associated with different STs. Most notably, ST127, which, based on phylogenetic analysis, appears to be a newly evolved clone, gave the highest virulence score. This virulent genotype may permit survival of ST127 isolates in the population long enough for them to gain antibiotic resistance. In contrast, multidrug resistant isolates of the ST131 clone were defined by a low virulence score and distinctive VF profiles.Metabolic reactions have been conventionally used for the classification of bacteria into families and species. Interestingly, in the assessment of the metabolic activity of different STs, members of the ST131 clone showed a high metabolic capacity compared to those of other STs, which may compensate for the low virulence capacity and explain the virulence reported for members of this ST. In contrast, ST127 showed the lowest metabolic capacity, even though it held the highest VF-score among the commonly detected STs. Multivariate logistic regression analysis demonstrated that ST131 is best described by its fluoroquinolone resistance and possession of PAI, the ibeA gene and expression of DR antigen-specific adhesins, whereas the O25b-CTX-M-15 ST131 sub-clone was only differentiated from the rest of the ST131 clone members by the production of Extended spectrum Beta-lactamase (ESBL) enzymes.EThOS - Electronic Theses Online ServiceLibyan governmentGBUnited Kingdo

Functional analysis of the accumulation associated protein (Aap) of Staphylococcus epidermidis

S. epidermidis is one of the primary opportunistic pathogens associated within dwelling medical devices such as intravenous catheters and artificial heart valves and joints. S. epidermidis is also a permanent commensal resident on human skin and mucus membranes providing a large potential reservoir for the contamination of medical implants. Persistent colonisation of implants occurs via biofilm formation and infected implants must usually be replaced. The surface bound protein, accumulation associated protein (Aap), is one of the main biofilm promoting surface molecules on S. epidermidis. Aap is a LPXTG protein with a repetitive B-region, thought to promote biofilm formation as well as providing a stalk structure to project the A-domain away from the cell surface. Aap is expressed in lateral tufts of fibrils on the surface of a sub-population of strain NCTC 11047 and, here, similar sub-populations are shown to be present in other S. epidermidis strains. In order to determine the function of specific domains of Aap in adhesion and biofilm formation Aap constructs with and without the A-domain and with varying numbers of B-repeats were expressed on the surface of Lactococcus lactis MG1363 and Staphylococcus aureus. The expression of Aap with the A-domain on the surface of L. lactis increased corneocyte adhesion 20-fold compared to L. lactis carrying Aap without an A domain. Several S. epidermidis isolates also used the A-domain of Aap to adhere to corneocytes, emphasizing the role of Aap in skin adhesion. In addition, Aap promoted adhesion to polystyrene although only the A-domain additionally promoted adhesion to tissue culture treated polystyrene. Furthermore, biofilms were cultivated under flow conditions and analyzed by confocal microscopy. Aap, with the A-domain on the surface of both L. lactis and S. aureus, enhanced microcolony formation suggesting a potential role for the A domain in the early stage of biofilm formation. The A-domain of Aap is therefore multifunctional because, in addition to mediating adhesion to corneocytes it can promote initial attachment to polystyrene and functions in the early accumulation stage of biofilm formation.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Review of Antimicrobial Nanocoatings in Medicine and Dentistry: Mechanisms of Action, Biocompatibility Performance, Safety, and Benefits Compared to Antibiotics

This review discusses topics relevant to the development of antimicrobial nanocoatings and nanoscale surface modifications for medical and dental applications. Nanomaterials have unique properties compared to their micro- and macro-scale counterparts and can be used to reduce or inhibit bacterial growth, surface colonization and biofilm development. Generally, nanocoatings exert their antimicrobial effects through biochemical reactions, production of reactive oxygen species or ionic release, while modified nanotopographies create a physically hostile surface for bacteria, killing cells via biomechanical damage. Nanocoatings may consist of metal nanoparticles including silver, copper, gold, zinc, titanium, and aluminum, while nonmetallic compounds used in nanocoatings may be carbon-based in the form of graphene or carbon nanotubes, or composed of silica or chitosan. Surface nanotopography can be modified by the inclusion of nanoprotrusions or black silicon. Two or more nanomaterials can be combined to form nanocomposites with distinct chemical or physical characteristics, allowing combination of different properties such as antimicrobial activity, biocompatibility, strength, and durability. Despite their wide range of applications in medical engineering, questions have been raised regarding potential toxicity and hazards. Current legal frameworks do not effectively regulate antimicrobial nanocoatings in matters of safety, with open questions remaining about risk analysis and occupational exposure limits not considering coating-based approaches. Bacterial resistance to nanomaterials is also a concern, especially where it may affect wider antimicrobial resistance. Nanocoatings have excellent potential for future use, but safe development of antimicrobials requires careful consideration of the "One Health" agenda, appropriate legislation, and risk assessment

Insights into a Multidrug Resistant Escherichia coli Pathogen of the Globally Disseminated ST131 Lineage: Genome Analysis and Virulence Mechanisms

Escherichia coli strains causing urinary tract infection (UTI) are increasingly recognized as belonging to specific clones. E. coli clone O25b:H4-ST131 has recently emerged globally as a leading multi-drug resistant pathogen causing urinary tract and bloodstream infections in hospitals and the community. While most molecular studies to date examine the mechanisms conferring multi-drug resistance in E. coli ST131, relatively little is known about their virulence potential. Here we examined E. coli ST131 clinical isolates from two geographically diverse collections, one representing the major pathogenic lineages causing UTI across the United Kingdom and a second representing UTI isolates from patients presenting at two large hospitals in Australia. We determined a draft genome sequence for one representative isolate, E. coli EC958, which produced CTX-M-15 extended-spectrum β-lactamase, CMY-23 type AmpC cephalosporinase and was resistant to ciprofloxacin. Comparative genome analysis indicated that EC958 encodes virulence genes commonly associated with uropathogenic E. coli (UPEC). The genome sequence of EC958 revealed a transposon insertion in the fimB gene encoding the activator of type 1 fimbriae, an important UPEC bladder colonization factor. We identified the same fimB transposon insertion in 59% of the ST131 UK isolates, as well as 71% of ST131 isolates from Australia, suggesting this mutation is common among E. coli ST131 strains. Insertional inactivation of fimB resulted in a phenotype resembling a slower off-to-on switching for type 1 fimbriae. Type 1 fimbriae expression could still be induced in fimB-null isolates; this correlated strongly with adherence to and invasion of human bladder cells and bladder colonisation in a mouse UTI model. We conclude that E. coli ST131 is a geographically widespread, antibiotic resistant clone that has the capacity to produce numerous virulence factors associated with UTI

Multiple metabolomics of uropathogenic E. coli reveal different information content in terms of metabolic potential compared to virulence factors.

No single analytical method can cover the whole metabolome and the choice of which platform to use may inadvertently introduce chemical selectivity. In order to investigate this we analysed a collection of uropathogenic Escherichia coli. The selected strains had previously undergone extensive characterisation using classical microbiological methods for a variety of metabolic tests and virulence factors. These bacteria were analysed using Fourier transform infrared (FT-IR) spectroscopy; gas chromatography mass spectrometry (GC-MS) after derivatisation of polar non-volatile analytes; as well as reversed-phase liquid chromatography mass spectrometry in both positive (LC-MS(+ve)) and negative (LC-MS(-ve)) electrospray ionisation modes. A comparison of the discriminatory ability of these four methods with the metabolic test and virulence factors was made using Procrustes transformations to ascertain which methods produce congruent results. We found that FT-IR and LC-MS(-ve), but not LC-MS(+ve), were comparable with each other and gave highly similar clustering compared with the virulence factors tests. By contrast, FT-IR and LC-MS(-ve) were not comparable to the metabolic tests, and we found that the GC-MS profiles were significantly more congruent with the metabolic tests than the virulence determinants. We conclude that metabolomics investigations may be biased to the analytical platform that is used and reflects the chemistry employed by the methods. We therefore consider that multiple platforms should be employed where possible and that the analyst should consider that there is a danger of false correlations between the analytical data and the biological characteristics of interest if the full metabolome has not been measured