5.4 antibiotic resistance II

Question 1

formation of biofilm, step 1.`

Answer 1

initial attachment
– when free floating bacteria adhere to the biomaterial surface
– attachment is facilitated by flagella/pili or by cell surface proteins

Question 2

biofilm formation step 2

Answer 2

cells aggregate, form micro colonies, and excrete extracellular polymeric substances.
– once cells attach, biofilm specific genes are expressed,
- these genes encode proteins that produce intracellular signalling molecules
– once committed to biofilm formation, expression of flagella genes stop, becoming non motile.

Question 3

biofilm formation step 3

Answer 3

maturation – biofilm develops containing polysaccharides that prevent antibiotic penetration

Question 4

biofilm formation step 4

Answer 4

3D growth, and further maturation – providing protection against host defense mechanisms.
– bacteria embedded in the film are simply inaccessible to antibiotics.

Question 5

biofilm formation step 5

Answer 5

biofilm reaches critical mass and disperses planktonic bacteria ready to colonize other surfaces.

Question 6

factors contributing to recent increase of antibiotic resistant organisms

Answer 6

resistant genes undergoing horizontal gene transfer, “germ-killing” chemicals, antibiotics fed to livestock, patients not taking complete course of antibiotics

Question 7

germ killing chemicals example

Answer 7

may have selected for bacteria that have acquired efflux pumps.
– kills 99.9% of the germs, but may leave that 0.1% of resistance to the chemical

Question 8

antibiotics fed to livestock example

Answer 8

antibiotics have been given to livestock to treat infections, but they have also been given to livestock to promote growth (more meat in less time) – people can get infected with harmful, resistant bacteria if food is undercooked.

Question 9

patients taking antibiotic for nonbacterial infections example

Answer 9

some people pressure their doctors into giving them antibiotics for a sore throat, but they dont know if its bacterial or viral. – might introduce antibiotics when it is not neede.d

Question 10

strategies for combating bacterial drug resistance

Answer 10

improve public health services and education,
limit antibiotic use,
higher initial does or combos of drugs w diff targets in the same treatment
monitor spread of drug resistant strains
seek new drugs
explore novel therapies.

Question 11

seek new drugs – unconventional combat example

Answer 11

teixobactin - discovered in 2015
– compound is specific for gram positive bacteria, people have not been able to generate mutants that are resistant to it, but still not ready for human trials.

Question 12

explore novel therapies – fecal transplant

Answer 12

an attempt to restore colon the bacteria that will make it healthy.
– feces is transferred from the rectup up into the GI tract, or fecal bacteria are purified and freeze dried in pill form.

Question 13

novel therapies – bacteriophage therapy

Answer 13

have a throat infection caused by a known bacterium? – can be provided with throat rinse containing phages that kill specific bacterium with no antibiotic resistance.
– the receptors on the tail fibres of bacteriophages recognize specific molecules on the surface of the host bacterial cell (lock and key)