Return of the Germ

Antibiotics were suppose to wipe out infectious bacteria. What went wrong?

Lethal Infections

• Date the microbial resurgence to the late 1970’s and early 1980’s, with the appearance of:– Lyme Disease– Legionnaires’ disease– toxic shock syndrome– AIDS

“Flesh-Eating Bug”

• England, June 1993• 11 deaths• Streptococcus pyogenes• Strep A bacteria• Bacteria secrete a toxin

that kills tissue

Jack in the Box• Contaminated Hamburger Meat• December, 1992• 500 people became ill

– 41 with acute kidney failure– 4 children die

• E.coli bacteria, which lives in the intestines of humans and animals but sometimes get into hamburger meat

Water Born Parasite

• Cryptosporidium• 1/2 population of

Milwaukee fell ill– 4,400 hospitalized– 104 died

• One-celled intestinal parasite turned up in the drinking water

Infectious Diseases

• Until WWII infectious diseases were the major cause of death in the U.S.

• Introduction of penicillin in the 1940’s began the era of antibiotics, the most important development in the battle against infectious diseases.

• 1969, Surgeon General Stewart “It is time to close the book on infectious disease.”

Why are they coming back?

• Center for Disease Control warned that we are in an era when “the spectrum of infectious diseases is expanding, and many infectious diseases once thought to be controlled are increasing”

Causes

• “Human populations-- immigrants and refugees-- are moving in unprecedented numbers across borders and into areas where they may be exposed to new infectious agents.” Harvard School of Public Health

• Environmental changes

Lyme Disease

• Changes in land use fueled its rise or return.

• Caused by a spirochete (bacterium) carried by deer ticks whose bites transmit the infection.

• Causes Fatigue, painful joints and memory loss.

AIDS Virus

AIDS

• May have spawned by environmental changes encountering social ones.

• Viruses closely related to HIV are believed to have been present for centuries in African primates.

• Humans turning jungles into farmland encroached on these animals’ territories.

• A monkey bite may have introduced HIV to humans.

Monkey Theory• Infected people moving from rural areas to cites

brought the virus.• Changing sexual morals (prostitution) increasing

sexually transmitted diseases and an the open lesions they cause allowed the disease to spread.

• 1980’s, Rapid global travel introduced the virus to the West. Here it exploded with promiscuous sexual activity and IV drug users sharing needles.

Is Retaliation Possible?

• The emergence of AIDS and other infections created a need for an early warning system.

• Unfortunately, antibiotics, our shield against infectious diseases for 50 years, are losing power.

• Microbes have evolved in resistant strains.

Drug-Resistant Strains• Hospitals housing patients with weakened

immune systems (AIDS, trauma/burn, chemotherapy, the elderly, and premature babies) have become a major breeding ground for resistant strains.

• Antibiotics will not kill all of the microbes against which it is targeted -- a healthy immune system is needed to destroy the hardier ones that are not susceptible.

“Survival of the Fittest”

• The massive amounts of antibiotics used in hospitals (about 1/3 of all patients receive them) creates a “survival of the fittest” situation that encourages drug-resistant bacterial strains to evolve, flourish and spread from patient to patient.

Hospitals

• Each year about 2 million patients (5% of people hospitalized) suffer hospital-caused infections, which result in about 60,000 deaths.

• An estimated 50% to 60% of hospital infections involve bacteria resistant to one or more antibiotics.

Drug-Resistant Problem

• Actually not new, first turned up after penicillin was introduced.

• If you use an antibiotic, you will develop a resistance.

• What is needed is a new class of drugs, unfortunately the task of keeping up with the microbes can prove daunting.

What causes the resistance?

• The one microbe in a million that survives an antibiotic attack may have a mutation that made it more resistant, or it may contain a resistant plasmid (circular ring of DNA outside the nucleus).

• A gene in that plasmid produces a protein that can neutralize the antibiotic.

Drug-Resistant Bacteria

• The survivor can produce millions of antibiotic-resistant offspring.

• The survivor can swap its resistance plasmid with other bacteria, including those of other species.

“Super Bugs”

• Hospital-bred “super bugs” are not solely responsible for the increase in antibiotic resistant bacteria.

• Another threat is day care centers

Day Care Centers

• Two factors to blame:– Pediatricians set the stage for drug resistant

infections by indiscriminately prescribing antibiotics for kids (especially for ear infections)

– Children congregating in day care centers pass on the resistant bugs to each other and later to families and society at large.

Steps to Minimize Your Risk

• Make sure you and your family get all your immunizations.

• Recognize that antibiotics will not work for viruses.

• Take the pills for the length of time prescribed.• Be vigilant about microbes on produce.• Be sure to cook all meat thouroughly.

Steps to Minimize Your Risk

• When traveling to other countries find out which disease organisms are currently problems and get immunization for them.

• Make sure your dogs and cats are immunized properly.

• Avoid contact with mice and other rodents (other than pets).

Questions?