Chapter 9: Drugs for Bacterial, Viral, and Fungal Infections

At certain times, we become susceptible to different types of infections caused by bacteria, viruses, or fungi. Typically, the immune system in the body is strong enough to repel or destroy the invading microorganism. Situations do occur, however, when the body's immune system is not able to combat and control an invasion by one or more of these microorganisms. When microbes overload the natural immune system, the body requires assistance to control the invasion. During these instances, chemotherapeutics (chemical agents that fight organisms such as bacteria, viruses, and fungi) are prescribed to control or eliminate the infection. In this chapter, we will study three categories of chemotherapeutic agents—antibiotics and antiviral and antifungal agents—and discuss their mechanisms of action in fighting invading microorganisms.

Bacteria

Bacteria are classified according to their general structure and makeup. They are small unicellular microorganisms (about the size of mitochondria) contained within a cell wall. Their genetic material is not contained in a true nuclear membrane. Bacteria cells lack the processes of mitosis and meiosis, and their genetic organization is simpler than that of cells in multicellular plants and animals.¹⁶ Bacteria are able to maintain cellular metabolism. However, they require nutrients and prefer to steal from their host the necessary amino acids, sugars, and other products they need to sustain life. By understanding the needs of bacteria, we can begin to appreciate how they compete with their human host for these nutrients.

Some bacteria are beneficial to humans. For example, the bacteria in the gastrointestinal (GI) system assist in the digestion of food and help to limit the growth of other microorganisms and excess production of some stomach acids. These helpful bacteria, the normal flora of the GI system, should not be destroyed on a regular basis. However, they are sometimes casualties of antibacterial treatment. It is sometimes necessary to restore these normal GI flora after an antibiotic regimen.

Types of Antibiotics

Bacterial infections must be diagnosed and treated by a physician. Treatment of a bacterial invasion is typically accomplished by a regimen of antibiotic therapy. There are several ways to classify antibiotics. For this book we will use the categories of spectrum of activity and method of bacterial control. Antibiotics can be described by their spectrum of activity: either narrow or broad. Narrow-spectrum antibiotics are active only against very specific microorganisms. Conversely, broad-spectrum antibiotics are active against many different categories of bacterial microorganisms. For example, when treating someone with an ear infection, you may want to fight only the bacteria causing the infection. You would use a narrow-spectrum antibiotic so that your treatment regimen does not destroy other bacteria found in the body. A broad-spectrum antibiotic is used when the exact invading bacteria have not been identified. For example, if a person is admitted to the hospital with pneumonia, broad-spectrum antibiotics are started immediately until cultures have been taken and the exact microorganism causing the infection is known.

Antibiotics can also be classified as bactericidal or bacteriostatic. Bactericidal antibiotics can completely destroy the bacteria. Bacteriostatic antibiotics suppress bacterial growth but cannot destroy the bacteria by their own mechanisms. They must rely on support from the immune system of the host.

Once the exact invading bacterial microorganism is known, it is important to choose the appropriate antibiotic. This choice depends on three criteria: (1) identification of the organism, (2) drug sensitivity of the invading organism, and (3) host factors.⁸

To effectively identify the invading organisms, Gram stain tests are ordered. Gram staining is the process of using crystal violet solution and iodine to identify the type of cell wall structure as either gram positive or gram negative. Gram-positive bacteria cell walls retain the violet stain, whereas gram-negative bacteria cell walls stain red. Through this quick method, the type of organism can be identified and appropriate treatment can be started. Samples used for gram staining can be obtained from various sources, but usually are from pus, sputum, urine, blood, or other bodily fluids. Taking direct samples from the site of infection is usually warranted.

Defining drug sensitivity to the invading organism is a common practice because of the emergence of drug-resistant organisms. There are two common methods to assess drug sensitivity: a disk-diffusion (Kirby-Bauer) test or a broth dilution procedure. Although a discussion of how they work is beyond the scope of this text, both procedures are effective in identifying the types of antibiotics to which certain bacteria may be resistant, thereby identifying the appropriate antibiotic treatment. The disk and broth diffusion procedures also help to determine the immunity of the microorganisms to a particular antibiotic. Later in this chapter we discuss in detail some of the emerging causes and problems associated with bacterial resistance.

The last step in choosing the appropriate antibiotic is determining host factors. One of the primary host factors is the natural defense mechanism (immune system). Someone with an impaired immune system will need different antibiotics from someone with a normally functioning immune system. The site of infection and the concentration of the antibiotic at the site of infection also play an important role in effective treatment. The blood-brain barrier, vascularity, or other impediments can alter the function and concentration of antibiotic therapy. Other factors, such as age, pregnancy, and genetic disposition, can also alter drug therapy. All these factors must be taken into consideration when a health-care professional chooses an antibiotic.

An athletic trainer's knowledge regarding antibiotic therapy does not have to be as complete as the attending physician's. However, it is important for the athletic trainer to be able to understand and explain to the athlete the general process by which an antibiotic works in the body. Therefore, in this section of the chapter, we will discuss antibiotics according to their mechanisms of action: (1) inhibition of bacterial cell-wall synthesis, (2) inhibition of bacterial protein synthesis, (3) inhibition of bacterial DNA synthesis, and (4) inhibition of folic acid synthesis. As we describe the mechanism of action for each drug, we will also refer to the class of the drug so that the reader will have a second way to remember each of these antibiotic drugs.

Antibiotics That Inhibit Cell Wall Synthesis

Penicillin

Penicillin was discovered in 1928 in Alexander Fleming's laboratory when mold was mistakenly introduced into bacteria being grown in a Petri dish. Initially, the scientist was going to discard the contaminated Petri dish, but then he noticed that the bacteria in the dish were dying around this contaminated area. Fleming looked closely at the contaminant and determined that it was mold. After it was determined that the penicillin produced by the mold would kill bacteria, he proceeded to experiment with the amount needed to destroy the microorganisms. Fleming went on to determine whether or not this new substance was toxic to life forms by injecting a rabbit that had an infection with what he termed "mold broth," and the rabbit appeared to get better. Over the next 15 years, as the result of still more research and development and the discovery of how to produce it in mass quantities, penicillin became available to the general population.¹⁹ It was the weapon needed to fight infections that previously been life threatening. Penicillin is able to effectively inhibit bacterial cell wall synthesis by passing through the small pores on a bacterium's cell membrane and binding to penicillin-binding proteins (PBPs). By attaching to PBPs, penicillin is able to inhibit specific enzymes that allow construction of the bacterium's cell wall. The bacterium cannot maintain its structure because of the decreased stability of the cell wall. The wall then collapses and the contents of the bacterium are forced out. Because mammalian cells lack a cell wall, penicillin has virtually no effect on the cells of the host.⁹ Most bacterial cell walls contain PBPs that are not found in animal cells. Therefore penicillin can be effective in selectively destroying some bacteria without affecting the animal or human host cells.¹²

Penicillins all have the same basic chemical structure, called a beta-lactam ring (Fig 9–1). This ring is essential for the antibacterial activity of penicillin. Unfortunately, the beta-lactam ring of the penicillin is a very weak structure. Some bacteria are able to produce an enzyme called beta-lactamase that cleaves the ring structure and inactivates the antibiotic. This is one example of a method by which bacteria are starting to develop resistance to antibiotics.

Penicillins are available in oral and injectable formulations and are used to treat infections, particularly those caused by gram-positive bacteria. These include ear infections, pneumonia, and skin infections. Other penicillin classes are able to treat gram-negative bacteria, which cause problems such as urinary tract infections, gynecological infections, and pneumonia.

The most common adverse effect of penicillin is hypersensitivity reaction, otherwise known as allergic reaction. The patient may develop a rash, itching, swelling, or a more serious anaphylactic reaction involving bronchospasm, vasomotor collapse, and laryngeal edema.⁶ Rashes and fevers usually do not appear until after several days of therapy, but anaphylaxis may occur within 10 minutes. Other adverse effects are usually related to disrupted GI function. Patients may experience nausea, vomiting, or diarrhea. Hypersensitivity and gastrointestinal reactions can occur with any antibiotic class; therefore, maintenance of allergy information for each patient is vital to ensure correct antibiotic selection.

Patients receiving any antibiotic treatment should be asked if they have an allergy to the medication and, if so, the type of reaction that occurred. If the patient reports a minor reaction, such as itching, he or she may be able to continue that specific drug therapy. In more severe reactions, the patient should change therapy to another drug class. In either case, the physician must be made aware of any abnormal reaction to a medication.

Cephalosporins

The first cephalosporin was isolated in 1948 from the sea near the Sardinian coast. Today cephalosporins are among the most commonly prescribed classes of antibiotic agents by physicians in outpatient and inpatient settings. Cephalosporins have a mechanism of action and structure (beta-lactam ring) similar to those of the penicillins. Because of this ring, cephalosporins are also susceptible to beta lactamase destruction.

Unlike the penicillins, the cephalosporin agents have developed into a hierarchical classification by chemical structure generation. Cephalosporins are currently divided into four generations, each based on general features of its antimicrobial activity. First-generation cephalosporins are most effective at fighting gram-positive bacteria. Second-through fourth-generation cephalosporins have increasing effectiveness against gram-negative bacteria while at the same time fighting gram-positive bacteria.

Because of this wide range of effectiveness, cephalosporins are used to treat many different types of bacterial infections. They are effective in treating skin and soft tissue infections, respiratory tract infections, and even meningitis. Cephalosporins are available in oral and injectable formulations. Most are effectively absorbed by the body and excreted via the kidneys.

Cephalosporin hypersensitivity reactions, similar to those of the penicillins, are the most common adverse effect noted. Because of the drugs' similar beta-lactam structures, patients who are allergic to penicillins may develop a cross-reactivity to cephalosporins.¹⁴ However, many patients who have mild allergic reactions to penicillins are able to take cephalosporins. If a patient develops severe hypersensitivity reactions to penicillins, cephalosporins can be prescribed, but with great caution.

Antibiotics That Inhibit Protein Synthesis

Another mechanism of action of antimicrobial agents is the inhibition of bacterial protein synthesis. These antibiotics are able to bind to bacterial ribosomes and block the production of new amino acids needed for protein synthesis.

Common classes of agents that inhibit bacterial protein synthesis include tetracyclines, macrolides, and clindamycin. These antibiotics are also bacteriostatic and suppress bacterial growth. Another class of antibiotics that inhibit bacterial protein synthesis is the aminoglycosides. They are a little different because, in addition to inhibiting bacterial protein synthesis, they exert bactericidal activity. There are other agents that inhibit protein synthesis, but they will not be included in this discussion because they are used specifically in the treatment of hospitalized patients.

Tetracyclines

Tetracyclines are a broad-spectrum class of antibiotics. These agents are effective against a variety of gram-positive and -negative organisms. Importantly, they are also effective in treating infections caused by rickettsias, such as Rocky Mountain spotted fever; and spirochetes, such as Lyme disease and syphilis. Commonly used agents include tetracycline, doxycycline, and minocycline.

Tetracyclines are readily absorbed from the stomach and small intestine. This absorption is impaired by concurrent administration of any products containing calcium, magnesium, aluminum, iron, or zinc. Therefore tetracyclines should not be taken with dairy products, iron, antacids containing aluminum, calcium or magnesium, or supplements containing zinc. If an athlete needs any of these supplements, tetracyclines may be administered 1 hour before or 2 hours after ingestion of the calcium, vitamin, or other mineral product.

The most common adverse effect of the tetracycline class is GI upset. To decrease the incidence of this upset, these agents can be taken with food as long as it does not contain the previously mentioned products. Photosensitivity reactions have also occurred with tetracyclines. When photosensitivity reactions occur, the skin becomes more sensitive to ultraviolet light. This is commonly recognized as an exaggerated sunburn. Patients should be advised to avoid prolonged exposure to the sunlight, wear protective clothing, and apply sunscreen to exposed skin. Tetracyclines also bind to calcium in the developing teeth of children and can result in a yellow or brown discoloration of the teeth. This discoloration is permanent and is related to dose, not duration of therapy.

Macrolides

Macrolides are another class of agents that have the ability to inhibit bacterial protein synthesis and are bacteriostatic in nature. These agents have a spectrum of activity similar to that of penicillins and are effective for persons who have an allergy to the penicillin class. Common agents in this class include erythromycin, azithromycin, and clarithromycin.

These agents are all available in oral formulations; some also have intravenous forms. It is important to note that some of these agents may be taken with or without food. This will affect the absorption rate, and therefore the athletic trainer should ensure that the athlete reads the instructions for taking the medication.

The most reported adverse effect of macrolides is GI disturbances. These effects are most severe with erythromycin. Macrolides have also been reported to have drug interactions with other agents. Because of the drug interactions, it is important to have all prescription medications dispensed from the same pharmacy. This will ensure that all potential drug interactions are reviewed by a pharmacist.

Clindamycin

Unique unto itself, clindamycin is the only agent in its class. Clindamycin has antibacterial activity that is similar to that of erythromycin but is effective against anaerobes, bacteria that can flourish without oxygen. Clindamycin absorption is not affected by food. Diarrhea is the most common adverse effect. It occurs in 2 to 20 percent of people taking this drug.²

Aminoglycosides

Aminoglycosides are agents that inhibit bacterial protein synthesis, are bactericidal in nature, and most commonly provide coverage against gram-negative bacteria. Aminoglycosides are formed by two or more amino sugars connected by a glycoside linkage, hence their name. Drugs in this class include gentamicin, tobramycin, amikacin, and neomycin. Neomycin, is commonly found in topical preparations for treatment of infections of the eye, ear, and skin.

Aminoglycosides are effective antibiotics but are reserved for hospitalized patients because most of them can be given only via intravenous infusion. Aminoglycosides are rapidly distributed throughout the body after IV administration and collect in the urine. They can also be used topically for some wound care. Because of their exclusive elimination by the kidney, the pharmacist or physician must continually monitor these drugs to determine if dose adjustments are necessary based on the individual's renal function. These agents can also cause ototoxicity and thus may result in impaired hearing or balance.

Antibiotics That Inhibit DNA Synthesis

Fluoroquinolones

Fluoroquinolones are popular agents used to treat broad-spectrum bacterial infections.¹³ These agents exert their antibacterial activity by inhibiting the coiling process of the bacterial DNA. Some agents included in this class are ciprofloxacin, levofloxacin, gatifloxacin, and moxifloxacin. Most are available in oral and intravenous formulations.

Adverse effects that sometimes occur with fluoroquinolones include central nervous system (CNS) effects such as headache and dizziness, GI upset, and arthropathy. This class of agents is not commonly used in children.

Recently, animal studies have reported an incidence of tendon rupture in fluoroquinolone use. The Achilles tendon is most commonly involved.^7,20 Fluoroquinolones disrupt the extracellular matrix of the cartilage and therefore should be discontinued if tendon pain or inflammation occurs. They have a food-drug interaction similar to that with tetracyclines, and therefore fluoroquinolones should not be administered concurrently with aluminum, magnesium, calcium, iron, or zinc products because of the decreased absorption of fluoroquinolones by the body.

Antibiotics That Inhibit Folic Acid Synthesis

Sulfonamides

Sulfonamides ("sulfa drugs") were used even before penicillin to treat bacterial infections initially, these drugs were used because they significantly decreased morbidity and mortality from invading bacterial infections. However, they are not the most effective antibacterial agents for fighting many different types of bacteria. After the introduction of penicillin, this class of agents slowly lost favor. Sulfonamides are still used today; however, they are mainly used in the treatment of urinary tract infections. They are able to eradicate bacteria by inhibiting folic acid synthesis, thereby producing a bacteriostatic effect. Common agents include sulfadiazine and sulfamethoxazole (a component of Bactrim). Common adverse effects are usually of the hypersensitivity type.

Adverse Effects of Antibiotics

In our discussion of the different types of antibiotics we have mentioned some of the adverse effects, however it is important for the athletic trainer to have an awareness of the general adverse effects associated with antibiotics. Hypersensitivity to antibiotics is not a common reaction in most people, but it can occur even after the athlete has been taking the medication for a few days or longer. Adverse effects that an athlete might experience when taking antibiotics include diarrhea, gastrointestinal upset, nausea, vomiting, itching, swelling, skin rashes, and difficulty breathing. In some individuals this hypersensitivity can result in an anaphylactic reaction, leading to severe bronchoconstriction and cardiovascular collapse.

Additionally, as mentioned, some antibiotics may produce an ultraviolet sensitivity, also known as a photosensitivity reaction. An athlete taking an antibiotic may become more susceptible to sunburn or other ultraviolet insult to the skin. It is always wise to warn athletes of this potential problem because of the outdoor location of many sports. Also, there have been a few anecdotal reports of a reduction in the effectiveness of birth control pills during the course of an antibiotic regimen.⁴ It is wise to tell female athletes who take birth control pills that the pills' effectiveness may be diminished during the period of antibiotic therapy.

Because the drugs are antibacterial, the helpful bacteria that normally exist in the gastrointestinal tract may also be contained and destroyed. To more rapidly replenish normal gastrointestinal flora, the athlete can eat yogurt after he or she has finished taking the entire course of antibiotics.

Minor Skin Infections

Athletes participating in almost any sport will at some time experience a minor cut or laceration to the skin. If these minor accidents result in a superficial skin infection, or if the athletic trainer wants to avoid minor complications from this trauma, readily available OTC topical antibiotics can be used. Many OTC antibiotic ointments are triple antibiotic preparations; that is, they typically contain the three main types of antimicrobial agents in smaller concentrations. Generally, these ointments contain small amounts of antibiotics that (1) inhibit cell wall activity, (2) inhibit protein synthesis, or (3) inhibit DNA synthesis of bacteria. Topical application of one of these ointments can destroy the microbes that may exist on or around the infected area.

Antibiotic Resistance

A growing health-care problem that appears to be getting worse as time goes on is the reduced efficacy of antibiotics to contain or destroy bacterial organisms.^3,23 Some strains of bacteria are becoming resistant to existing antibacterial drugs, and the greatest resistance patterns are in the United States and Latin America.¹⁵ This resistance has various etiologies. One is the beta-lactamase enzyme, which was discussed previously. This enzyme is becoming more prevalent in society and therefore causes more bacterial resistance. Stuart Levy, a diligent researcher in this area, has written an article about antibiotic resistance that will be informative to those interested in this ongoing problem.¹⁰ In monitoring the effectiveness of tetracyclines over three decades, it has been demonstrated that the growth in resistance in some strains of bacteria over that period has increased from 30 to 80 percent. This can be considered a major setback for tetracycline effectiveness over time,²¹ and other antibiotics are experiencing antibiotic resistance as well.

Other researchers discuss the mutations that occur in bacteria over the years.¹⁷ Many people who take antibiotics take only a portion of the dosage. For example, they may start to feel better and stop taking the antibiotic. However, the entire colony of bacteria may not be contained or destroyed, and the surviving bacteria can mutate and become more resistant to the antibacterial medication being taken. This is a good reason to consistently remind athletes taking an antibiotic to be fully compliant and take the entire course of the prescription, even if they start to feel better before they have completed the total prescription. Even if an athlete has 2 or 3 days of medication left to take and insists that he or she feels "fine," continue to encourage the athlete to finish the entire prescription.

Another reason that has been suggested for the increase in bacterial resistance is the overprescribing of antibiotics by physicians. Swain and Kaplan²² boldly state that antibiotics are overused in the treatment of upper respiratory infections. The prescription of antibiotics is beyond the scope of practice of the athletic trainer. However, we mention this issue so that the athletic trainer can explain to athletes why a physician will not prescribe antibiotics for a sore throat. Most sore throats are a symptom of a viral infection, such as a common cold, on which an antibiotic will not have any effect. Medications for the common cold will be discussed farther on in this chapter under the heading "Antiviral Agents."

Recently there has been a growing discussion regarding the use of antibiotics to prevent infection in farm animals raised for human consumption.⁵ Some farmers and ranchers have been using antibiotic supplements in animal feed to maintain health in the animal during its growth period and before it goes to market. It is suggested that residual antibiotics in meat allow bacteria in the body to mutate. Once the bacteria mutate, they become difficult to control by the normal defense mechanisms of the body. This theory is of recent origin, and research in this area is ongoing. There is not a great deal of definitive information at this time. In 1997 the United States, in collaboration with a number of other countries around the world, began collecting data on antimicrobial resistance.¹⁵ The antibiotic resistance scheme used in the United States is called SENTRY Antimicrobial Surveillance and includes 30 sites that report to a main center at the University of Iowa. This system is linked to similar systems for monitoring antibiotic resistance in Europe, Asia, and Central and South America. The objective of SENTRY is to provide a worldwide network of laboratories that will monitor and provide timely information about hospital- and community-acquired infections, among other priorities.¹⁵ In the United States there are state- and county-level groups that are attempting to reduce bacterial resistance by educating the public about the proper use of antibiotics.

In response to the problems of antibiotic resistance numerous scientists and laboratory personnel are working diligently on developing new antimicrobial drugs. One of the most recent advances is a drug called quinupristin-dalfopristin, which was approved by the FDA in 1999 for serious or life-threatening illnesses associated with severe bacterial infections.¹¹ This is a new class of antibiotic. Its desired action is to impair bacterial protein synthesis. It is currently being successfully implemented in the hospital setting. Additionally, scientists and drug companies are continuing research to discover new types of drugs that will successfully destroy or deter microbial activity in humans and animals.

Antiviral Agents

When a virus invades the human body, it brings with it only the necessary DNA or RNA to replicate. The capsid holding the DNA or RNA invades the body either via an airborne mechanism or through an opening in the skin. When the capsid enters the body, it finds a host cell and releases its replication materials into that cell. The virus, in essence, takes over one of the cells of the human body and uses the cellular mechanism to reproduce more DNA or RNA, which is released and takes over other cells within the same host. The virus causes the host's cells to cease functioning normally and utilizes cellular mechanics to propagate the virus. This continues until the body can produce enough appropriate antibodies to destroy the virus without destroying its own system.

A virus invading a human host is a very small microorganism and can be relatively benign, severe, or fatal, depending on its type. The common cold is a good example of a viral infection that typically has only minor repercussions for the human host if cared for properly. However, the common cold can also be extremely debilitating and can develop into a possibly fatal illness if proper care procedures are not followed. In contrast, almost everyone is aware of the ramifications of the human immunodeficiency virus (HIV), and most people do everything possible to avoid contact with this virus because it is almost always lethal in the long term.

As mentioned, a viral infection can manifest as a cold, flu, or other system-wide disturbance. It can also be localized: for example, a cold sore or wart located on one small part of the body. Many, if not all, athletes experience some type of viral infection at some point in their athletic career. Therefore the athletic trainer should be familiar with viruses and their treatment.

Oral Medications

One of the more common antiviral medications is acyclovir, commonly prescribed to contain an outbreak of the herpes simplex virus. It is prescribed for treatment of initial and recurrent episodes of the herpes virus, including cold sores and chickenpox, as well as genital herpes outbreaks. Acyclovir inhibits viral DNA replication in the host cell. When the genetic material cannot be replicated and passed on, the virus eventually succumbs to the host's immune system. Acyclovir and other prescription antiviral agents are described in Table 9–2.

New drugs are being developed for viral infections. Some of those are OTC medications for the care of minor viral infections such as cold sores and fever blisters. One of the most recent is docosanol (Abreva). It has a 10 percent active ingredient, can be purchased OTC, and claims to shorten the healing time for cold sores.

Other antiviral medications target the influenza virus. Drugs such as zanamivir (Relenza, see Table 9–2) work with the body's immune system to decrease the duration of flu symptoms. If you want an athlete to use antiviral drugs to reduce flu symptoms, it is critical to get the athlete to the physician as soon as the flu symptoms start. The sooner the athlete starts taking the prescription medication, the quicker the symptoms will subside. Relenza and similar antivirals must be taken within 48 hours of the onset of symptoms to be effective

Vaccines

Vaccines are most commonly associated with the influenza virus but are also available for other viral infections. Vaccines are prepared by a method in which either an entire virus or part of a virus is completely or partially inactivated through laboratory procedures so that it does not replicate. This attenuated virus is then injected into the human host. The immune system of the human host, stimulated by an inactive invader that resembles a live virus, proceeds to generate and store antibodies to this virus in the body. If the actual live virus does invade the body, there is a supply of antibodies to immediately attack and stop reproduction of the virus in the human host.

The development of vaccines has been extremely helpful in avoiding many viral infections, some of which can be fatal to their human host (Table 9–3). Vaccines are not yet available for every type of virus. Most notably, no vaccine exists for HIV, which leads to acquired immunodeficiency syndrome (AIDS). Treatment of HIV and AIDS is beyond the scope of the athletic trainer and will not be discussed in detail here.

There are many thousands of fungus species in nature. A very small percentage of these species can cause an infection on or in the human body. A fungus is a plantlike organism that can exist in either air or soil. Many fungal infections in the human are considered opportunistic infections and occur on the epidermis. A cutaneous fungal infection needs three environmental conditions to develop, multiply, and sustain life in a human host: warmth, darkness, and moisture. Proper hygiene and the normal defense mechanisms of the body are the common tactics for reducing the possibility of fungal infections in athletes. However, when these normal modes of control are not available, fungal infections can occur on, or sometimes in, the body.

Many times a cutaneous fungal infestation is referred to as a "tinea" infection. Tinea refers to the skin, and most athletic-related fungal infections have the word "tinea" in their names. For example, tinea capitis is ringworm of the scalp; tinea corporis is a fungal infection on the trunk area; tinea cruris, commonly known as "jock itch," occurs in the perineal area, and tinea pedis is athlete's foot. This last infection is very common in athletes playing a variety of sports and can occur in athletes of any gender or age. Nail fungus (onychomycosis) is another common fungal infection experienced by athletes.

Fungal infections can be spread by direct or indirect contact. Using community showers, having bodily contact with the skin of infected athletes (as in wrestling), lack of good hygiene on the part of the athlete, or any of numerous other contamination procedures can lead to a fungal infection in the athlete. Fungal infections that are allowed to develop over a longer time period usually take longer to resolve.

Some types of fungi find a way to get inside the body and multiply. This produces a much greater threat to human function than the conditions described in the previous few paragraphs. One way in which fungi get into the human body is through inadequate care of a cutaneous fungal infection, allowing it to become so advanced that the skin dries and cracks, opening the inside of the body to the infection. Another inopportune type of infection occurs when fungal spores become airborne and an athlete inhales the airborne fungus, resulting in a respiratory infection. Respiratory fungal growths such as coccidioidomycosis require the use of prescription antifungal medications. Systemic fungal growth is beyond the scope of the athletic trainer's duties and will not be discussed here.

Oral and Topical Medications

There are prescription oral and topical medications that the physician can prescribe if a fungal infection is not controlled by an OTC preparation. However, the antifungal medications most commonly seen by athletic trainers are OTC topical medications. Most topical antifungal preparations take from 1 week to 1 or more months (depending on the severity of the infection) to completely control the fungal infection. Athletes need to understand that a fungal infection will not go away overnight, and might not even go away in a week. But, with the correct antifungal (Table 9–4), the athlete should be able to derive some benefit from the medication after the first week and be encouraged that further treatment will completely resolve the fungal problem.

The main control mechanism of topical antifungals is the impairment of cell membrane synthesis. An antifungal typically controls some of the key enzymes that help to build or maintain the cell membrane. Thus, the cell cannot function normally and the fungus dies.

Adverse Effects of Antifungal Agents

Topical antifungal agents are generally very safe and have few, if any, adverse effects. There is a possibility that an athlete may be allergic to one of these topical preparations. Oral antifungals can demonstrate a variety of toxicities to the hepatic, cardiovascular, and other systems. Check with the athlete's physician to determine if there are any signs or symptoms of adverse effects that you should watch for. Observe the area being treated and speak with the athlete daily regarding any adverse effects.

1. Possible adverse effects of penicillin include which of the following?

   1. Hypersensitivity reaction

   2. GI distress

   3. Nausea/vomiting

   4. All of the above

2. Antibacterial drugs work in a variety of ways. Which one of the following is not a way in which these drugs work?

   1. Inhibiting cell wall synthesis

   2. Inhibiting prostaglandin release

   3. Inhibiting protein synthesis

   4. Inhibiting DNA/RNA function

3. Bacterial resistance can occur from all of the following except:

   1. Certain strains of bacteria enzymatically destroying the antibacterial drug.

   2. Noncompliance by the athlete in taking the full course of the drug.

   3. Bacterial evolution.

   4. Combining anti-inflammatories with antibiotics.

4. Which of the following adverse effects is quickly noticed in a reaction to antibiotics?

   1. Fever

   2. Tinnitus

   3. Skin rash

   4. Dizziness

5. The cephalosporins are a class of:

   1. Antibiotics

   2. Synthetic hormones

   3. Anti-inflammatories

   4. Antivirals

6. Bactericidal antibiotics are so classified because their mission is to:

   1. Kill and destroy bacteria

   2. Limit the growth or proliferation of bacteria

   3. Cause death to the host organism

   4. Limit the DNA production of the cell

7. An antiviral drug's mechanism of action is usually:

   1. Cell wall destruction

   2. Inhibition of DNA activity

   3. Stopping of cellular activity

   4. Bactericidal

8. Vaccines inhibit viral infections from becoming active in the human body is through the use of:

   1. A live virus

   2. An inactivated virus

   3. Reconstructed antibiotics

   4. All of the above

9. When an athlete is experiencing a common cold, it is advisable for the athletic trainer to do advise the athlete to do which of the following?

   1. Use aspirin to control the fever

   2. Get antibiotics for the sore throat

   3. Use OTC medications to control the head congestion

   4. All of the above

10. In the human, a plantlike microorganism (fungus) can live:

    1. On the skin

    2. Under the dermal skin layer

    3. In the lungs

    4. All of the above

11. Most athletes will be dealing with which type of medication to control their fungal infections?

    1. Topical

    2. Systemic

    3. Intravenous

    4. Antibacterial

12. If an athlete has an allergic reaction to a prescribed antibiotic drug, you should tell him or her to:

    1. Try a different brand of the drug

    2. Tell the pharmacist and see if there is an alternative drug they could use

    3. Stop taking the drug immediately

    4. Take the medication with food