Microorganisms—A Small
Formidable Opponent
There are millions of microorganisms around us—and in our body. Some are
harmless. Others, called flora, help us with digestion. And then there are the harm-
ful ones called pathogens. A pathogen is a microorganism that causes an infection.
Pathogens enter our body in a variety of ways such as a cut or in food that we
ingest. Once inside, a race begins between the invading organism and the body’s
defenses. Our body reacts with an inflammatory response that dilates blood ves-
sels so they become permeable. This allows fluid containing white blood cells to
infiltrate the infected area. Nerve endings are stimulated and send a message
to your brain that there is something wrong.
You know when this happens because the infected area turns red, swollen,
and it hurts. The infection might be a patch of tissue referred to as a local infec-
tion. Other infections affect an organ or entire system of your body, which is
referred to as a systemic infection or septecemia. An infection can also affect
multiple organs and systems. This is called sepsis.
You can learn more about microbials by reading Microbiology Demystified.Medication—A Formidable Defender
Your natural defense against bacteria is a phagocytic response. Cells in your
body engulf a pathogen, basically eat it and remove the injured tissue. Many
times your body needs help from medication that can kill microbials.These are
called antimicrobials. An antimicrobial is a medication that kills a micro-
organism. There are many types of antimicrobials. Each is designed to kill
specific microorganisms. The most familiar is an antibiotic, which kills bacteria.
Antibiotics kill microbials—the good and the bad. For example, an antibiotic
used to kill bacteria that causes a urinary tract infection will also kill the flora in
your intestine that are used to help digest food.
Patients are also treated with medication that eases the symptoms of inflam-
mation but doesn’t kill microbials. These are prostaglandin inhibitors.
Prostaglandins are chemical mediators that bring about the inflammatory
response by vasodilatation, relaxing smooth muscle, making capillaries perme-
able, and sensitizing nerve cells within the affected area to pain. A prostaglandin(^204) CHAPTER 13 Antimicrobials—Fighting Infection