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Essay Instructions: Antibiotic resistance development in humans. General overview of specific strains, causes and effects. Sources must be current. Please include free bibliography.

Essay Instructions: Efficiency of antibiotic resistance gene transfer mechanisms upon exposure to triclosan

Abstract:

Humans live in constant contact with microbes, the vast majority of which do not cause disease. Pathogenic bacteria have frequent contact with commensal bacteria from human, animals, plants, fish, soil and water. These commensal bacteria, which often provide a benefit to the host, can serve as reservoirs for resistance genes; collecting them and holding them for future transmission of other organisms[1]. Ultimately, one of the recipients for this genetic largesse can be a disease causing bacterium.
Bacteria in every environment are constantly evolving aided in part by exchange of genetic material. Evidence is growing that extensive horizontal transfer of antibiotic resistance genes occur in nature between clinical and nonclinical bacteria [2]. Hence the commensal reservoir bacteria may be important players in the spread of antibiotic resistance genes. Methods of DNA transfer between organisms include transformation by naked DNA, viral transduction, and bacterial conjugation.
All mechanisms of DNA transfer involve the cell membrane. Since triclosan disrupts the microbial cell membrane, it is important to examine whether triclosan affects the acquisition of antibiotic resistance genes. Experiments would measure the efficiency of gene transfer between different classes of bacteria upon exposure of triclosan. Plasmids carrying marker genes such as those coding for tetracycline and kanamycin resistance will be introduced into several hosts (Escherichia coli, Staphylococcus aureus, Salmonella typhimurium, and Pseudomonas aeruginosa). The efficiency of transformation by naked DNA and gene transfer between bacteria vial bacterial conjugation can be examined upon exposure to various levels of triclosan. Likewise the ability of triclosan to inhibit bacteriophage infection, another common method of gene transfer will be analysed. Our focus on the alterations in the efficiencies of gene transfer mechanisms upon exposure to triclosan may elucidate novel physiological effects.






Works cited:

[1] Mazodier, P. and J. Davies. Gene Transfer Between Distantly Related Bacteria
Annu. Rev. Genet. 1991, Vol. 25: 147-171.

[2] Roberts, M. C. Tetracycline resistance determinants: mechanisms of action, regulation of expression, genetic mobility, and distribution, Pages 1-24
FEMS Microbiol. Rev., 1996. 19:p. 1-24.

Articles that may be relevant:
Tan L, Nielsen NH, Young DC, Trizna Z.
Use of antimicrobial agents in consumer products.
Arch Dermatol. 2002 Aug;138(8):1082-6.
PMID: 12164747 [PubMed - indexed for MEDLINE]

Fraise AP.
Susceptibility of antibiotic-resistant cocci to biocides.
J Appl Microbiol. 2002;92 Suppl:158S-62S.
PMID: 12000624 [PubMed - indexed for MEDLINE]

Russell AD.
Introduction of biocides into clinical practice and the impact on antibiotic-resistant bacteria.
J Appl Microbiol. 2002;92 Suppl:121S-35S. Review.
PMID: 12000621 [PubMed - indexed for MEDLINE]


Levy SB.
Active efflux, a common mechanism for biocide and antibiotic resistance.
J Appl Microbiol. 2002;92 Suppl:65S-71S. Review.
PMID: 12000614 [PubMed - indexed for MEDLINE]


Poole K.
Mechanisms of bacterial biocide and antibiotic resistance.
J Appl Microbiol. 2002;92 Suppl:55S-64S. Review.
PMID: 12000613 [PubMed - indexed for MEDLINE]

Loughlin MF, Jones MV, Lambert PA.
Pseudomonas aeruginosa cells adapted to benzalkonium chloride show resistance to other membrane-active agents but not to clinically relevant antibiotics.
J Antimicrob Chemother. 2002 Apr;49(4):631-9.
PMID: 11909837 [PubMed - indexed for MEDLINE]

Schweizer HP.
Triclosan: a widely used biocide and its link to antibiotics.
FEMS Microbiol Lett. 2001 Aug 7;202(1):1-7. Review.
PMID: 11506900 [PubMed - indexed for MEDLINE]

Levy SB.
Antibacterial household products: cause for concern.
Emerg Infect Dis. 2001;7(3 Suppl):512-5.
PMID: 11485643 [PubMed - indexed for MEDLINE]

Susman E.
Too clean for comfort.
Environ Health Perspect. 2001 Jan;109(1):A18. No abstract available.
PMID: 11171537 [PubMed - indexed for MEDLINE]


Chuanchuen R, Beinlich K, Hoang TT, Becher A, Karkhoff-Schweizer RR, Schweizer HP.
Cross-resistance between triclosan and antibiotics in Pseudomonas aeruginosa is mediated by multidrug efflux pumps: exposure of a susceptible mutant strain to triclosan selects nfxB mutants overexpressing MexCD-OprJ.
Antimicrob Agents Chemother. 2001 Feb;45(2):428-32.
PMID: 11158736 [PubMed - indexed for MEDLINE]

Levy SB.
Antibiotic and antiseptic resistance: impact on public health.
Pediatr Infect Dis J. 2000 Oct;19(10 Suppl):S120-2. Review.
PMID: 11052402 [PubMed - indexed for MEDLINE]

Suller MT, Russell AD.
Triclosan and antibiotic resistance in staphylococcus aureus.
J Antimicrob Chemother. 2000 Jul;46(1):11-8.
PMID: 10882683 [PubMed - in process]

Jones RD, Jampani HB, Newman JL, Lee AS.
Triclosan: a review of effectiveness and safety in health care settings.
Am J Infect Control. 2000 Apr;28(2):184-96. Review.
PMID: 10760227 [PubMed - indexed for MEDLINE]

Russell AD.
Do biocides select for antibiotic resistance?
J Pharm Pharmacol. 2000 Feb;52(2):227-33.
PMID: 10714955 [PubMed - indexed for MEDLINE]

Levy CW, Roujeinikova A, Sedelnikova S, Baker PJ, Stuitje AR, Slabas AR, Rice DW, Rafferty JB.
Molecular basis of triclosan activity.
Nature. 1999 Apr 1;398(6726):383-4. No abstract available.
PMID: 10201369 [PubMed - indexed for MEDLINE]

Tierno PM Jr.
Efficacy of triclosan.
Am J Infect Control. 1999 Feb;27(1):71-2; discussion 72-4. No abstract available.
PMID: 9949382 [PubMed - indexed for MEDLINE]

McMurry LM, Oethinger M, Levy SB.
Triclosan targets lipid synthesis.
Nature. 1998 Aug 6;394(6693):531-2. No abstract available.
PMID: 9707111 [PubMed - indexed for MEDLINE]

Essay Instructions: HYPOTHESIS: THE MACROLIDE ERYTHROMYCIN USED TO TREAT INDIVIDUALS WITH COMMUNITY ACQUIRED PNEUMONIA CAUSES ANTIBIOTIC RESISTANCE IN PATIENTS IN EUROPE , BUT NOT INDIVIDUALS IN THE UNITED STATES.
-Tables and graphs may also be used.

Include a Literature Cited section of at least six references from the primary literature (journal articles and books written for scientists), NOT from secondary or tertiary sources (e.g., Natural History Magazine, Scientific American, Science News, newspapers). Internet sources do not constitute acceptable references.

The proposal will be written like a scientific paper with the following sections: Abstract,Introduction, Materials and Methods, Discussion, and Literature Cited.Also page numbers are a must.

In the Introduction you will develop a testable hypothesis and at least one alternative hypothesis about your chosen topic. Carefully explain the logic behind the hypotheses you propose and state the prediction(s) and any important assumptions you are making. Does each hypothesis yield at least one unique prediction, and is it possible to collect information that would allow you to reject at least one hypothesis? Conduct bibliographic research to identify the existing literature on your topic, and cite articles related to your hypothesis in the Introduction.

In the Materials and Methods section of your proposal you will describe an experiment (or experiments) or set of observations that you will use to test your hypotheses. Make your experiment practical in that you could conduct it with the appropriate resources (equipment, time frame, etc.). Carefully explain the methods you would use and what you would measure. Use the active voice preferentially, e.g., "I will raise gorillas in cages and measure aggressive behavior directed at intruders to determine if aggression is related to fitness," as opposed to "the gorilla's reactions to unsuspecting volunteers will be measured."

In the Discussion section you will explain the different kinds of experimental results you may obtain, or the observations that would lead you to reject or fail to reject your hypotheses. (You do not know the outcome of your proposed experiment, but you can outline the range of possible outcomes

The Manuscript. The active voice is preferred. Manuscripts must be typewritten or printed on one side only of good quality, standard size (8.5 x 11, 21.5 x 28 cm) paper. The entire typescript should be double-spaced and should have one-inch margins throughout, including literature citations, tables, and captions to figures. Words should not be divided at the right-hand margin. Do not right-justify any portions of the text. Only use footnotes to clarify tables. Scientific names should be italicized, not underlined.

Essay Instructions: The topic is "The Evolution of Antibiotic Resistance." The final paper is written in scientific format (writing.colostate.edu/guides/processes/science/pop2a.cfm, http://classweb.gmu.edu/biologyresources/writingguide/ScientificPaper.htm) with a minimum of 5 citations. Meaning it has an abstract, introduction, materials and methods, results, discussion and conclusion. The abstract starts with a broad opening sentence, casts the problem you want to solve
includes the results, and then recast purpose of paper at the end again. The intro should end with purpose paragraph. The materials and methods are the databases you used to find your lit and search strings. Results are the results of those searches. The cited literature is using AMA style (http://www2.liu.edu/cwis/cwp/library/workshop/citation.htm) or APA and it's cited in text, too. The paper should not be written in 1st person. The paper should be 5 pages double spaced.