- MRSA Is Putting Resistance in the News
- Humans Live with Many Pathogens
- Antibiotics Block Growth and Kill Pathogens
- Broad-Spectrum Antibiotics Also Perturb Our Microbiomes
- Antibiotic Resistance Protects Pathogens
- Antibiotic Resistance Is Widespread
- Antibiotic Resistance Is Divided into Three Types
- The Development of New Antibiotics Is Slowing
- Vaccines Block Disease
Antibiotic Resistance Is Divided into Three Types
Antibiotic resistance is categorized into several types that require different solutions. One is called acquired resistance. As a natural part of life, mutant cells arise either spontaneously (about one in a million cells per generation) or from the transfer of resistance genes from other microbes (see Chapter 6). When a mutant is less susceptible to a particular antibiotic than its parent, mutant growth is favored during treatment. Eventually, the mutant becomes the dominant member of the pathogen population. One way to slow this process is to limit antibiotic use or use doses that block mutant growth.
When the "acquired" mutant starts to spread from person to person, it causes transmitted or disseminated resistance. In this second type of resistance, the pathogen is already resistant before treatment starts. Disseminated resistance is often highly visible and may elicit immediate action by the healthcare community. Much of that action is aimed at halting transmission.
A third type of resistance involves pathogen species unaffected by particular antibiotics. They are said to be intrinsically resistant. Little can be done about this type of resistance except to develop vaccines and use good infection control practices that keep the pathogens away from us. Most viruses fall in this category.