The Genetics of Antibiotic Resistance Research Theme: Infectious Diseases Jason Kuehner March 5, 2007

What’s wrong with this statement? Take a few minutes to individually complete this worksheet and then compare your answers with your group

What’s wrong with this statement? Take a few minutes to individually complete this worksheet and then compare your answers with your group Consider these misconceptions throughout class today and we’ll follow-up on them at the end

The Problem

You run a public health clinic in Racine, Wisconsin

The Problem You run a public health clinic in Racine, Wisconsin A county commissioner overseeing your clinic is an epidemiologist and wants to know how you plan to address the emergence of ciprofloxacin resistance in Neisseria gonorrhoeae

The Problem You run a public health clinic in Racine, Wisconsin A county commissioner overseeing your clinic is an epidemiologist and wants to know how you plan to address the emergence of ciprofloxacin resistance in Neisseria gonorrhoeae Medical professional that deals with the incidence, distribution, and possible control of diseases

The Problem You run a public health clinic in Racine, Wisconsin A county commissioner overseeing your clinic is an epidemiologist and wants to know how you plan to address the emergence of ciprofloxacin resistance in Neisseria gonorrhoeae Oral antibiotic approved for treatment of many common bacterial infections

The Problem You run a public health clinic in Racine, Wisconsin A county commissioner overseeing your clinic is an epidemiologist and wants to know how you plan to address the emergence of ciprofloxacin resistance in Neisseria gonorrhoeae Species of bacteria that is the causative agent of gonorrhea, a sexually transmitted infection

The Problem You run a public health clinic in Racine, Wisconsin A county commissioner overseeing your clinic is an epidemiologist and wants to know how you plan to address the emergence of ciprofloxacin resistance in Neisseria gonorrhoeae State budget cuts mean you cannot afford to give all of your patients more expensive antibiotics or do all of the lab tests that you would like

The Problem You run a public health clinic in Racine, Wisconsin A county commissioner overseeing your clinic is an epidemiologist and wants to know how you plan to address the emergence of ciprofloxacin resistance in Neisseria gonorrhoeae State budget cuts mean you cannot afford to give all of your patients more expensive antibiotics or do all of the lab tests that you would like  Develop a plan to address the medical, economic, and political questions your clinic will face in dealing with this public health issue

Sexually transmitted infection caused by the bacterium Neisseria gonorrhoeae Among the most common sexually transmitted infections (STI) in the world What is gonorrhea?

Gonorrhea is treated with antibiotics Antibiotic: chemical substance produced by or derived from a microorganism (molds or bacteria) that kills or inhibits the growth of bacteria Mold colony (Penicillium chrysogenum) Bacteria

Gonorrhea is treated with antibiotics Antibiotics help cure infections by decreasing the bacterial population to a level that the human immune system can handle Antibiotic treatment

Antibiotics disrupt essential cell processes

Outer cell membrane Cell wall Inner cell membrane + antibiotic (e.g. Penicillin) Cell wall construction

Antibiotics disrupt essential cell processes Cell wall construction

Antibiotics disrupt essential cell processes RNA DNA Protein Gene expression

Antibiotics disrupt essential cell processes RNA DNA Enzymes Cell structure Signaling Protein Gene expression

DNA replication occurs prior to cell division DNA replication Parent Cell Daughter Cells DNA

Antibiotics disrupt essential cell processes Replication DNA Gene expression

Antibiotics disrupt essential cell processes Transcription Replication DNA Gene expression RNA

Antibiotics disrupt essential cell processes Transcription Translation Replication DNA Gene expression RNA Protein

Antibiotics disrupt essential cell processes Transcription Translation Replication “Central Dogma of molecular biology” RNA Protein DNA Gene expression

Antibiotics disrupt essential cell processes Transcription Translation Replication + antibiotic RNA Protein DNA

Antibiotics disrupt essential cell processes Transcription Translation Replication + antibiotic RNA Protein DNA

Antibiotics disrupt essential cell processes Transcription Translation Replication + antibiotic RNA Protein DNA

Antibiotics disrupt essential cell processes Transcription Translation Replication + antibiotic Gene expression RNA Protein DNA

What is antibiotic resistance? The ability of bacteria to survive exposure to antibiotic drugs Antibiotic treatment

Resistance through alteration of drug target Enzyme active site antibiotic Wild type protein Mutant protein

Resistance through alteration of drug target antibiotic Wild type protein Mutant protein antibiotic Enzyme active site

DNA mutation can alter protein structure Wild typeMutant RNA Protein DNA

Genotype codes for the phenotype Every living organism is the outward physical manifestation of internally coded, inheritable, information

Genotype codes for the phenotype Every living organism is the outward physical manifestation of internally coded, inheritable information Genotype: The genetic constitution of an organism

Genotype codes for the phenotype Every living organism is the outward physical manifestation of internally coded, inheritable, information Genotype: The genetic constitution of an organism Phenotype: The physical features of an organism produced by the interaction of genotype and environment

Genotype codes for the phenotype RNA Protein DNA Genotype Phenotype Antibiotic Sensitivity antibiotic (Wild type)

Genotype codes for the phenotype RNA Protein DNA Genotype Phenotype Antibiotic Resistance antibiotic (Mutant)

The following statements describe how a change in genotype can perturb phenotype. Number them in the best sequential order (1=earliest event, 4=latest event): __ Mutant RNA is translated. __ Mutant DNA is transcribed. __ Mutant protein is altered, changing an organism’s response to its environment. __ An error occurs during DNA replication, resulting in a gene mutation. Genotype can perturb phenotype

The following statements describe how a change in genotype can perturb phenotype. Number them in the best sequential order (1=earliest event, 4=latest event): _3_ Mutant RNA is translated. _2_ Mutant DNA is transcribed. _4_ Mutant protein is altered, changing an organism’s response to its environment. _1_ An error occurs during DNA replication, resulting in a gene mutation. Genotype can perturb phenotype

Emergence of antibiotic resistance “It is not difficult to make microbes resistant to penicillin in the laboratory by exposing them to concentrations not sufficient to kill them, and the same thing has occasionally happened in the body.” - Alexander Fleming, 1945 Nobel Prize lecture

Gonococcal Isolate Surveillance Project (GISP) — Percent of Neisseria gonorrhoeae isolates with resistance or intermediate resistance to ciprofloxacin, 1990–2005 CDC STD Surveillance, 2005 Increasing resistance to antibiotics in US

Increasing resistance to UW UHS Gonorrhea Isolation –26 total cases Cervical/Vaginal (3) Urethral/Urine (14) Pharynx (4) Rectal (5) –9/9 non-genital isolates tested were ciprofloxacin resistant

Evolution of antibiotic resistance +++ Variation HeredityTime Selective Pressure

Evolution of antibiotic resistance Variation

Evolution of antibiotic resistance Variation Selective Pressure

Evolution of antibiotic resistance Variation Heredity Selective Pressure

Evolution of antibiotic resistance Variation HeredityTime Selective Pressure

Why aren’t antibiotics as effective as they used to be? What’s wrong with this statement?

1. People have become immune to antibiotics –Human immune systems do not build up immunity to antibiotics. Rather, it is the bacteria within the human host that become resistant. What’s wrong with this statement?

1. People have become immune to antibiotics –Human immune systems do not build up immunity to antibiotics. Rather, it is the bacteria within the human host that become resistant. 2. Antibiotics are changing and subsequently becoming weaker –Antibiotics are inert chemical substances. Bacteria, however, are living organisms that can change through evolution. What’s wrong with this statement?

1. People have become immune to antibiotics –Human immune systems do not build up immunity to antibiotics. Rather, it is the bacteria within the human host that become resistant. 2. Antibiotics are changing and subsequently becoming weaker –Antibiotics are inert chemical substances. Bacteria, however, are living organisms that can change through evolution. 3. Bacteria have mutated in order to become resistant –Bacteria do not “choose” to mutate, adapt, or develop resistance. Natural selection selects among whatever variation exists in the population and the result is evolution. What’s wrong with this statement?

1. People have become immune to antibiotics –Human immune systems do not build up immunity to antibiotics. Rather, it is the bacteria within the human host that become resistant. 2. Antibiotics are changing and subsequently becoming weaker –Antibiotics are inert chemical substances. Bacteria, however, are living organisms that can change through evolution. 3. Bacteria have mutated in order to become resistant –Bacteria do not “choose” to mutate, adapt, or develop resistance. Natural selection selects among whatever variation exists in the population and the result is evolution. 4. Antibiotics have mutated bacteria to become resistant –Antibiotics do not introduce mutations. Mutations occur randomly during DNA replication. What’s wrong with this statement?

Delaying the inevitable… 1.Don’t use antibiotics to treat viral infections. 2.Avoid mild doses of antibiotics over long time periods. 3.When treating a bacterial infection with antibiotics, take all of your pills. 4.Use a combination of drugs to treat a bacterial infection. 5.Reduce or eliminate the “preventative” use of antibiotics on livestock and crops.