Bruce H. Robinson, MD, FACS, MSOM (Hon)
Editor's Note: As discussed by Dr. Robinson in part 1, the purpose of this article series is not to endorse medication use, but rather to arm health care practitioners with the knowledge they can use when evaluating patients, most of whom are likely taking some form of medication.
Antibiotics
To understand antibiotics, it is important to remember there are different classes of bacteria. These are often differentiated by their staining qualities, which also correlate with their behavior and their sensitivity to antibiotics. There are gram-positive-staining bacte-ria (purple) and gram-negative bacteria (pink). There are also acid-fast-staining bacteria (the tuberculosis bacteria, for example).
Gram-positive bacteria generally live on the skin: Staphlococcus, Streptococccus and Pneumococcus. All cause soft-tissue infec-tions and pneumonia. Staph also causes infections everywhere else in the body. Staph causes abscesses; strep causes cellulitis (spread-ing infection).
Gram-negative bacteria generally live in the intestinal tract: E. coli, Pseudomonas, Aerobacter, Proteus, Salmonella, Campylobacter and Shigella. These bacteria often cause intestinal or urinary tract infections.
Acid-fast bacteria: Mycobacterium tuberculosum is the best known. It causes tuberculosis, with nodular infections in the lungs and other areas of the body. These infections are slow-growing and require a long time for treatment (usually a year). Prior to antibiotics, tuberculosis was one of the greatest killers on Earth. Leprosy is also an acid-fast bacteria (very slow growing and causing slow destruc-tion).
Treatment of gram-positive bacteria: Once sensitive to penicillin, these bacteria have become quite resistant to it in recent years. Most staph skin infections do respond well to oral first-generation cephalosporins (there are four generations) such as cephalexin (Ke-flex) and cephazolin (Ancef). These antibiotics are a backbone of medical practice, as such infections affect all of us at one time or an-other. More serious gram-positive infections, such as pneumonia or osteomylitis, require IV Nafcillin and oral dicloxacillin.
Amoxacillin or augmentin (amoxicillin plus clavulinic acid) are used to treat otitis media and sinus infections, which, if un-checked, may lead to brain abscesses, especially in diabetic patients or the elderly.
For methacillin-resistant staph infections (MRSA): Vancomycin and Rocephin are given together, IV. Sulfa is also sometimes used (it's curious this would work). These infections require aggressive treatment, often in the hospital, as they can be life-threatening.
Treatment of gram-negative bacteria: Pathogenic gram-negative bacteria are common in serious intestinal tract infections (such as peritonitis from a ruptured appendix) or upper urinary tract infections (pyelonephritis). For serious infections of this sort, third-generation cephalosporins such as ceftriaxone are used IV, and have saved many lives. Aminoglycosides such as gentamycin are also very effective.
Tuberculosis responds well to isoniazid and rifampin, taken over six to 12 months, depending on the severity of the infection.
Fungal infections: These infections are common in the mouth or vagina. They respond well to various anti-fungal agents such as mycostatin or ketaconazole. For more serious systemic fungal infections, such as fungal myocarditis (seen in AIDS patients), amphotericinB is used. Those who take it often call it amphoterrible because of the nausea, vomiting, dizziness and other side effects, but they continue to take it because it works well when needed.
Antiviral Drugs
Relenza and Tamiflu moderate the severity of influenza and the bird flu virus. The government has stockpiled huge quantities of these agents in case there is a bird flu epidemic, as happened in 1918 with the death of at least 50 million people. Hopefully they will not be needed on a mass basis, but these agents are also used to treat the elderly and children who develop severe seasonal influenza that requires hospitalization. Amantadine (Symmetryl) is also used to treat regular seasonal influenza in the elderly.
Antiviral therapy: Herpes genitalis and oralis are among the most common viral infections in this country. Acyclovir (Zovirax) is still widely used, and is inexpensive, but it has to be taken five times a day! For this reason, valcyclovir (Valtrex) has become the drug of choice, as it needs only a twice-a-day dose. Famcyclivir (Famvir) is also available.
Treatment of HIV and AIDS should be covered in a separate article, but I will mention three of the most popular drugs: zidovudine (Retrovir), lamivudine (Epivir) and abacavir (Ziagen). There are about 20 other drugs, usually combined together into a three-agent cocktail, to diminish the development of drug resistance.
Antiparasite drugs: Parasite infections are everywhere in the tropics and throughout Third World countries due to hot weather plus poor sanitary conditions. Malaria still kills over a million people worldwide every year. Amebiasis is a scourge that kills hundreds of thousands. Other parasites abound in these other countries and parts of the world.
Parasite infections in the U.S.: Giardia, an intestinal infection, and Trichomonas vaginalis, which causes vaginitis, are the two most common parasites here. Both are treated with metronidazole (Flagyl). Pinworms are common in schoolchildren and can then infect the whole family. They are treated with mebenazole (Vermox), taken by mouth by the entire family if one child shows up with pinworms, which crawl out of the anus at night and lay their eggs, causing intense anal itching.
Scabies and head, body and pubic lice are treated with Lindane shampoo (Kwell). Lice are flea-sized crawling bugs, easy to see with the naked eye. Scabies are microscopic and burrow under the skin, causing red lines that are intensely itchy (can be almost maddening). Proper attention to personal hygiene and sanitation is essential to avoid these infestations, along with thoughtful selection of potential romantic partners in the case of scabies and pubic lice.
Anti-Inflammatory and Immunosuppressant Drugs
Infectious agents provoke inflammatory responses, and pharmacologists have developed many anti-inflammatory agents over the years that are very helpful in reducing inflammation. A true wonder drug in this regard is aspirin because it has so many beneficial effects. It lowers fever, reduces inflammation, combats pain and helps prevent blood clots, all at the same time.
Aspirin manages to do this because it blocks the enzyme cyclooxygenase. This enzyme catalyzes the formation of a group of chemicals known as prostaglandins that travel throughout the body in times of infection. These prostaglandins have a role in producing fever, encouraging platelet aggregation, provoking the inflammatory response (redness, heat, swelling) and then facilitating the perception of pain. These reactions are all intended to protect us and help us cope with whatever is infecting or otherwise assaulting us. However, when we have redness, heat, and swelling of the nose, sinuses and throat, we would rather block those reactions if possible.
Other nonsteroidal anti-inflammatory drugs (NSAIDs): acetaminophen (Tylenol), ibuprofen (Motrin, Advil), naproxen (Naprosyn, Aleve), Celebrex (fewer GI side effects than the others above, but possible cardiac toxicity in some people).
Side effects for all NSAIDs include GI upset and bleeding, especially with prolonged use or overdose. NSAIDs are among the most widely used drugs and are over-the-counter; thus, very easy to obtain. GI bleeding as a side effect of these agents takes a heavy toll of American lives each year.
Corticosteroids are even more potent anti-inflammatory agents than NSAIDs and are a mainstay of treating autoimmune disorders: cortisone, prednisone, Aristocort, Medrol, etc. The long-term use of steroids leads to Cushing's syndrome, with diabetes, hypertension, fluid retention, osteoporosis and stomach ulcers, along with many other unpleasant features.
They are nonetheless miracle drugs because of their powerful beneficial effects in reducing inflammation and swelling. Steroids save the lives of many individuals with closed head trauma from auto accidents and falls who might otherwise die from increased swelling of the brain.
Drugs that suppress the activity of the immune system have been developed and are widely used in autoimmune disorders: methotrexate, azathioprine (Imuran) and cyclophosphamide (Cytoxan). Newer agents block the actions of TNF, the tumor necrosis factor: inflixamab (Remicaid) and etanercept (Enbrel). These are expensive drugs that work wonders in helping those with severe rheumatoid arthritis, lupus, or any of the other less-well-known autoimmune disorders. Insurance companies are now starting to recognize the dramatic value of these drugs in severe illness and are paying for their use.
Part 1 of this article appeared in the Nov. 18, 2012 issue of DC; part 2 ran in the July 1, 2013 issue; and part 3 appeared in the Oct. 15 issue.
