“Hand washing is the single most important means of preventing the spread of infection".

-- US Centers for Disease Control

Agenda for Today

Bacterial Resistance to Antibiotics

John Snow and the Pump

Antibiotic Resistance

Antibiotic use selects for populations of antibiotic-resistant pathogens.

For example, some bacteria avoid the effect of penicillin by the production of penicillinase, an enzyme that destroys penicillin.

Antibiotics and other life-saving drugs used against many diseases are rapidly losing their effectiveness as bacteria and other microbes develop resistance to them.

For example, doctors worldwide are losing some of the most useful and affordable antibiotics against the two principal bacteria which cause pneumonia, the major cause of death in children.

“S. pneumoniae is a common source of bacterial infections in children, the elderly and AIDS patients, says Tomasz.

Worldwide, the number of deaths from infections with this bacteria each year are similar to that of tuberculosis--3 to 4 million.”

“A strain of the bacterium Streptococcus pneumoniae, resistant to the six most frequently used antibiotics and spread worldwide including U.S. day care centers and hospitals, appears to disguise itself from the immune system by changing its coat, report scientists from The Rockefeller University.”

Antibiotic resistance genes are often found on plasmids.

Resistance genes can be transferred from one species to another.

Plasmids can accumulate genes for resistance to many antibiotics.

Examples of Antibiotic Resistance Genes

Resistance to Penicillin:

Penicillinase

Tetracycline:

A membrane pump

Things people do that increase the rate at which antibiotic resistant bacteria become more common

Agricultural Use

Over-use; misuse

Patient non-compliance

About 5 percent of patients who enter acute-care hospitals acquire infections from their hospitalization, and the incidence of drug-resistant strains of the most common of these so-called nosocomial infections (e.g., Staphylococcus aureus) is on the rise.

1854: John Snow

In one particular neighborhood, the intersection of Cambridge Street and Broad Street, the concentration of cholera cases was so great that the number of deaths reached over 500 in 10 days

Snow investigated the situation and concluded that the cause was centered around the Broad Street pump.

His solution?

Have the pump handle removed

Cholera

Transmission: water-borne

The bacterium that causes cholera is Vibrio cholerae

The disease can spread in situations of massive overcrowding without adequate safe drinking water and sanitation.

Cholera can almost always be treated with oral rehydration therapy

In 1991, inadequate sanitation brought on an epidemic of cholera in South America for the first time inalmost a century.