Gene transfer in the GI tract and oral cavity

Gene transfer is important in spreading antibiotic resistance and other traits such as virulence factors. In this review the molecular mechanisms of gene transfer are outlined and the biological consequences of bacterial gene transfer in the GI tract and the oral cavity (GIOC) are discussed. Finally areas of possible future research aimed at attaining a deeper understanding of the process of gene transfer and the potential for stopping or slowing unwanted transfer are discussed

The use of analyst-user cognitive style differentials to predict aspects of user satisfaction with information systems

This study was primarily an empirical investigation in the field of Information Systems (IS) and the related fields of occupational psychology and management. It focussed specifically on the concept of user satisfaction, the construct of cognitive style as applied to users and systems analysts, and their interrelationships. Prior studies were found rarely to investigate the changes in user satisfaction during system usage. Further, any reference to cognitive style in the IS literature proved to be sparse, open to question and discouraging in terms of its value. By developing and using a new instrument, the System Satisfaction Schedule, or SSS, the present study was able empirically to demonstrate clear patterns of changing user satisfaction during system usage. These were demonstrated, both as a general trend and in terms of its relationship to the cognitive styles of the key players (analyst and user) involved in system development and maintenance. Cognitive style was measured using Kirton's Adaption-innovation Inventory, or KAI. This study was thus able to suggest new rules for system development based on the assessments of the cognitive styles of both users and systems analysts. These rules focussed primarily on simple team choice: which analyst to put with which user. However, inferences for larger system development teams were drawn and suggestions for further research duly made. The present study thus also contributes to the successful practice of system development. To give effect to the above, this study set out to investigate empirically the way user satisfaction changes over 1½ to 2 years of system usage and, as mentioned above, the way user satisfaction is impacted by the cognitive styles of the user and the systems analyst. Most significantly, relationships were studied between user satisfaction and the difference in cognitive style between the analyst and user. It was found that user satisfaction generally rises linearly with usage, and that while the size of the analyst user cognitive differential does negatively impact user satisfaction over most of the time of system use, this effect is only particularly strong for two short periods; one within the first four months of usage and the other in the last three. From these results the new rules for system development mentioned above, followed. In terms of the decline of users' mean perceived severities of individual problems, the exponential decay and reciprocal models were found to fit the data the best. This study developed a new model for the motivation to use, develop or maintain a system (the Mechanical Model), based on its own results and Herzberg's two-factor theory of motivation. In this, Herzberg's hygiene factors have been replaced with the concept of dissatisfiers. These are measured as expressions of dissatisfaction as and when they occur. Their use removes the researcher's need, when designing user satisfaction instruments, to speculate on complete lists of factors which may satisfy users, and which may date as technology and other contextual factors change

Phage ϕC2 mediates transduction of Tn6215, encoding erythromycin resistance, between Clostridium difficile strains

UNLABELLED: In this work, we show that Clostridium difficile phage ϕC2 transduces erm(B), which confers erythromycin resistance, from a donor to a recipient strain at a frequency of 10(-6) per PFU. The transductants were lysogenic for ϕC2 and contained the erm(B) gene in a novel transposon, Tn6215. This element is 13,008 bp in length and contains 17 putative open reading frames (ORFs). It could also be transferred at a lower frequency by filter mating. IMPORTANCE: Clostridium difficile is a major human pathogen that causes diarrhea that can be persistent and difficult to resolve using antibiotics. C. difficile is potentially zoonotic and has been detected in animals, food, and environmental samples. C. difficile genomes contain large portions of horizontally acquired genetic elements. The conjugative elements have been reasonably well studied, but transduction has not yet been demonstrated. Here, we show for the first time transduction as a mechanism for the transfer of a novel genetic element in C. difficile. Transduction may also be a useful tool for the genetic manipulation of C. difficile.Peer reviewe

PCR-based detection of composite transposons and translocatable units from oral metagenomic DNA

A composite transposon is a mobile genetic element consisting of two insertion sequences (ISs) flanking a segment of cargo DNA often containing antibiotic resistance (AR) genes. Composite transposons can move as a discreet unit. There have been recently several reports on a novel mechanism of movement of an IS26-based composite transposon through the formation of a translocatable unit (TU), carrying the internal DNA segment of a composite transposon and one copy of a flanking IS. In this study, we determined the presence of composite transposons and TUs in human oral metagenomic DNA using PCR primers from common IS elements. Analysis of resulting amplicons showed four different IS1216 composite transposons and one IS257 composite transposon in our metagenomic sample. As our PCR strategy would also detect TUs, PCR was carried out to detect circular TUs predicted to originate from these composite transposons. We confirmed the presence of two novel TUs, one containing an experimentally proven antiseptic resistance gene and another containing a putative universal stress response protein (UspA) encoding gene. This is the first report of a PCR strategy to amplify the DNA segment on composite transposons and TUs in metagenomic DNA. This can be used to identify AR genes associated with a variety of mobile genetic elements from metagenomes

'Am I anorexic?': weight, eating and discourses of the body in online adolescent health communication

This article explores the communicative choices of adolescents seeking advice from an internet-based health forum run by medical professionals. Techniques from the disciplines of sociolinguistics and corpus linguistics are integrated to examine the strategies used in adolescents’ health questions. We focus on the emergent theme of Weight and Eating, a concern which features prominently in adolescents’ requests to medical practitioners. The majority of advice requests are authored by adolescent girls, with queries peaking at age 12. A combined quantitative and qualitative analysis provides detailed insights into adolescents’ communicative strategies. Examinations of question types, register and a discourse-based analysis draw attention to dominant discourses of the body, including a ‘discourse of slenderness’ and a ‘discourse of normality’, which exercise negative influences on adolescents’ dietary behaviours. The findings are of applied linguistic relevance to health practitioners and educators as they provide them with access to adolescents’ health queries in their own language

Draft Genome Sequence of Eggerthia catenaformis Strain MAR1 Isolated from Saliva of Healthy Humans

Here, we report the draft genome sequence of Eggerthia catenaformis MAR1 isolated during a screen for d-cycloserine-resistant bacteria from the saliva of healthy humans. Analysis of the genome reveals that the strain has the potential to be a human pathogen and carries genes related to virulence and antibiotic resistance

New perspectives on language and gender: Linguistic prescription and compliance in call centres

Despite a shift to service-based economies, male-dominated, high-status workplaces have been the predominant focus of research into language and gender in the workplace. This study redresses this shortcoming by considering one female-dominated, low-status, highly regimented workplace that is emblematic of the globalized service economy: call centres. Drawing on 187 call centre service interactions, institutional documents, interviews, and observations from call centres in two national contexts, the study employs an innovative combination of quantitative and qualitative discourse-analytic techniques to compare rule compliance of male and female workers. Female agents in both national contexts are found to comply more with the linguistic prescriptions despite managers and agents emphatically denying the relevance of gender. The study offers a new perspective on language and gender, pointing to the need to expand the methodologies and theories currently favoured to understand how language perpetuates occupational segregation in twenty-first-century workplaces

The Tn916/Tn1545 Family of Conjugative Transposon

The conjugative transposon Tn916 was first discovered in the late 1970s and is, together with the related conjugative transposon Tn1545, the paradigm of a large family of related conjugative transposons known as the Tn916/Tn1545 family, which are found in an extremely diverse range of bacteria. With the huge increase in bacterial genomic sequence data available, due to the widespread use of next generation sequencing, more putative conjugative transposons belonging to the Tn916/Tn1545 family are being reported. Many of these are capable of excision, integration and conjugation. Nearly all of the Tn916/Tn1545‑like elements discovered to date encode tetracycline resistance however, increasingly resistance to other antimicrobials is being found. Some of the members of the Tn916/Tn1545 family of elements are composite structures which contain smaller mobile genetic elements which are also capable of transposition. Tn916/Tn1545‑like elements themselves are also found within larger and more complex elements. This review will give an overview of the current knowledge of the Tn916/Tn1545 family of conjugative transposons highlighting recently characterized composite elements carrying additional and novel resistance genes

TetAB46, a predicted heterodimeric ABC transporter conferring tetracycline resistance in Streptococcus australis isolated from the oral cavity.

OBJECTIVES: To identify the genes responsible for tetracycline resistance in a strain of Streptococcus australis isolated from pooled saliva from healthy volunteers in France. S. australis is a viridans Streptococcus, originally isolated from the oral cavity of children in Australia, and subsequently reported in the lungs of cystic fibrosis patients and as a cause of invasive disease in an elderly patient. METHODS: Agar containing 2 mg/L tetracycline was used for the isolation of tetracycline-resistant organisms. A genomic library in Escherichia coli was used to isolate the tetracycline resistance determinant. In-frame deletions and chromosomal repair were used to confirm function. Antibiotic susceptibility was determined by agar dilution and disc diffusion assay. RESULTS: The tetracycline resistance determinant from S. australis FRStet12 was isolated from a genomic library in E. coli and DNA sequencing showed two open reading frames predicted to encode proteins with similarity to multidrug resistance-type ABC transporters. Both genes were required for tetracycline resistance (to both the naturally occurring and semi-synthetic tetracyclines) and they were designated tetAB(46). CONCLUSIONS: This is the first report of a predicted ABC transporter conferring tetracycline resistance in a member of the oral microbiota