Microbiology - R. of Microbes - Ch. 4

Microbes – Ch. 4: Antibiotic-Resistant Bacteria in the News

*Most members of the public are confused about antibiotics and antibiotic-resistant bacteria
1. Most reporters do not have any background in basic biology of bacteria
2. Antibiotic use has become so pervasive in modern times and varied in application that it is difficult to keep up with most recent incarnation of antibiotic resistance problem
3. Antibiotic story is rich in potential villains
-Portrays are basically inaccurate and ultimately destructive to rational public debate about how to manage antibiotic discovery process or antibiotic use guidelines

*Mid-1990s: stories of antibiotic resistance begin to develop heavily
-Slowly developing trend into galloping crisis
*More realistic vision of future:
-Most disease-causing bacteria remain susceptible to at least a few antibiotics (not a total loss of antibiotics)
*Preventing infections (past 60 years)
-Prevent transmission in hospitals by using disinfectants/antiseptics – isolating patients
-Alcohol-based disinfectant lotions
-Infection prevention and control in communities (improved nutrition/less crowed areas)
-Advent of less invasive forms of surgery (localized; laser; etc) → rapid surgery
-New ‘smart cancer drugs’ – target tumor cells and not WBCs
-Use of vaccines/nonantibiotic strategies such as viruses that kill bacteria (bacteriophages) or bacterial proteins that kill bacteria (bacteriocins)

*Antibiotic loss effects
-Public’s reaction to a situation in which cures that had been taken for granted suddenly become less effective or no longer available
-“Evolution” Nancy Kress
~Murder of a doctor treated small (low class) girl with one remaining effective antibiotic
~Did not want unnecessary use of antibiotics on ‘wrong people’

*Other places of antibiotic resistance
1. Genetically modified plants as foods
-Antibiotic resistance gene (incorporated into plant genome)
-Can the gene be released from the plant in the human/animal digestive tract and enter bacteria normally in the colon?
-Deadly bacteria if escape from colon = antibiotic-resistant (surgery)
2. Found in H2O supplies (pollutants)

3. Bioterrorism (anthrax)
-Took ciprofloxacin (high side effects) vs. Doxycycline
-If normal microflora bacteria become resistant to one class of our frontline antibiotics, the ciprofloxacin class of antibiotics is no longer useful for treatment of postsurgical infections caused by them
4. Antibiotics in agriculture use
-Growth promoting use vs. preventing diseases
-CDC estimates at least as many tons of antibiotics are used in agriculture as are used to treat human disease
-Many of agriculture antibiotics are closely related in structure to important antibiotics used in humans and can cross-select for resistance to antibiotics used in treatment of human infections
EX: Avoparcin (vancomycin): growth promoter – can select for resistance to vancomycin
-Tons of antibiotics being washed in H2O supplies
-Antibiotic resistant bacteria selected on farm enter and move through food supply into human body
*Antibiotics in agriculture:
A. Sick animals (10-15%)
B. Prophylaxis - administration to prevent disease, factory farms (30%)
C. Growth promoters – growth advantage in weight
~May work to prevent disease
~Effect on bacteria – leads to reduced turnover and excretion of cells which line the intestine

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