ur struggle for survival has always entailed a battle against the countless microbes with which we share the earth. Hostile bacteria, viruses, fungi, and parasites invade our bodies and go to war with our immune systems. To fight back, we must call forth all our strength and defenses. Plagues and epidemics are as much a part of our history as any struggle between nations.
Though it may seem hard to believe, prior to the use of penicillin during World War II, physicians had no effective medicines to treat serious infections. Fifty years later, we have more than 100 different antibiotics--including sulfa drugs, synthetic penicillin, and many, many more--to ward off the full spectrum of bacterial diseases. The development of numerous vaccines has virtually wiped out many former killers, both bacterial and viral, in the U.S. and many other developed countries.
Yet infection still plagues us, despite these gains. Many strains of bacteria are now resistant to the drugs that once killed them. Most viruses are impervious to antiviral drugs. Some microorganisms come in so many different forms that a single vaccine just can't cope with them all. Other microorganisms elude treatment by hiding in hard to reach areas such as the central nervous system and bones. Then too, some people today are simply exposed to a wider range of diseases because of our increased mobility, the use of immunosuppressive drugs, and such invasive procedures as surgery and catheterization.
Consequently, infection is still a serious threat, even in our highly advanced society. In Third World countries, infectious diseases continue to cause widespread mortality.
How Infections Cause Illness
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When organisms invade the body, they reproduce and multiply rapidly. In the process, the microorganisms compete with the body's metabolic processes. Some also produce toxins that injure cells. What's more, our own immune response may actually cause even further tissue damage. How sick someone actually gets as a result of the infectious process depends on the type and number of invading organisms and the person's overall health and strength.
Staph Infections
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Staphylococcal bacteria produce a wide range of diseases, causing anything from skin eruptions to blood poisoning (bacteremia) and death. Staphylococcal infections include the following conditions:
Bacteremia, the presence of bacteria in the blood, is characterized by a high fever, shaking chills, racing heart, pallor, agitation, and joint pain. It may progress to confusion and stupor, and can be fatal in just 12 hours. Treatment must begin immediately with semisynthetic penicillin (nafcillin or methicillin) or cephalosporins (cefazolin) given intravenously. People who are allergic to penicillin or are infected by penicillin-resistant organisms must be treated with vancomycin.
The symptoms of staphylococcal pneumonia are similar to those of other pneumonias--sudden onset of high fever, cough with yellow or bloody sputum, difficulty in breathing, and chest pain. Treatment consists of the same medication used for bacteremia.
The use of some of these drugs, particularly broad-spectrum antibiotics like cephalosporins, sometimes brings on enterocolitis (inflammation of the intestines). This condition is marked by profuse, watery diarrhea; abdominal pain; nausea; vomiting; and dehydration. If a patient develops enterocolitis, the antibiotics must be stopped at once and replaced with a different drug, such as vancomycin.
Osteomyelitis is a bone infection that occurs as a complication of a blood-borne infection, or as a sequel of surgery or trauma. Osteomyelitis may come on rapidly, exhibiting fever, sudden pain, swelling, tenderness, heat, and restricted movement in the affected bone. Its onset can also be insidious, however, with fever as the first warning. Treatment consists of surgery to open and cleanse the wound and large doses of antibiotics for four to eight weeks.
Staphylococcal bacteria are among the most common causes of food poisoning. Symptoms of food poisoning include nausea, loss of appetite, diarrhea, vomiting, and abdominal cramps. Since the symptoms typically subside within 18 hours, there's usually no need for treatment unless the person shows signs of dehydration. Full recovery takes one to three days.
Some skin infections owe their source to staphylococcal bacteria as well. These infections are manifested by widespread inflammation of soft tissue (cellulitis), and pus-producing or boil-like lesions, sometimes accompanied by fever and discomfort. Treatment includes applying mupirocin ointment (Bactroban), as well as administering oral antibiotics (erythromycin, dicloxacillin, or cloxacillin). Severe infections are treated with intravenous oxacillin, methicillin, or nafcillin. Ointments such as bacitracin-neomycin-polymyxin are used to prevent further infection of broken skin.
Toxic shock syndrome (TSS) is an acute infection that is sometimes associated with tampon use during menstruation. The symptoms of toxic shock syndrome include a high fever, an abrupt episode of shivering and chills, intense muscle pain, profuse watery diarrhea, headache, and vomiting. A dark red rash appears on the palms and soles within a few hours. Shock may develop within 48 hours.
TSS is treated with antibiotics, such as oxacillin, methicillin, and nafcillin, given intravenously.
Strep Infections
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A total of 21 species of streptococcal bacteria have been identified, but three classes--Groups A, B, and D--are responsible for most infections.
Group A bacteria cause the following infections:
Streptococcal pharyngitis accounts for the majority of sore throats caused by bacteria. Children between the ages of five and 10 years get most of these strep throats--mainly from October through April. The symptoms of strep throat may include a fever, severe pain and difficulty swallowing, inflamed tonsils, a sore and red throat, a "strawberry'' appearance of the tongue, enlarged lymph nodes, loss of appetite, weakness, malaise, and abdominal discomfort.
Sometimes, however, the symptoms of strep throat are mild, and the infection escapes detection. Left untreated, a strep infection can lead to rheumatic fever.
It is essential that anyone with a strep throat take the full prescription of antibiotics--usually either penicillin or erythromycin. Isolation from others for 24 hours after starting antibiotic therapy is recommended to prevent the disease from spreading.
Scarlet fever may occur along with a strep throat, certain wound infections, and blood poisoning. Children between the ages of two and 10 years are most likely to get scarlet fever. Symptoms include those of strep throat plus a sunburn-like rash that feels like sandpaper to the touch. The rash usually begins on the upper chest and then spreads to the rest of the body. Prompt treatment with an antibiotic is essential.
Erysipelas is another type of strep infection. It usually occurs in infants and in adults over 30 years of age. When erysipelas develops, swollen, red, raised lesions with a raised, firm border suddenly appear and spread. Other symptoms include headache, vomiting, fever, and irritability. An antibiotic should be administered promptly. Cold packs and analgesics, such as aspirin and codeine, can alleviate local pain.
Other infections caused by streptococcal A bacteria include impetigo (skin lesions with itching and encrustment) and lymphadenitis (red-streaked, painful skin lesions with fever, racing heart, and lethargy.) Both infections require treatment with antibiotics.
Group B streptococcal infections include newborn and adult forms. The adult form usually occurs after women give birth. Both newborn and adult infections are usually treated by penicillin or ampicillin. Group D streptococcal bacteria are frequently implicated in endocarditis, an inflammation of the interior of the heart.
Various strains of strep are among the causes of other diseases, including pneumonia (see Chapter 6 on respiratory disorders); otitis media (fluid in the middle ear); and meningitis. All of these infections are treated with penicillin, amoxicillin, or ampicillin.
Meningitis
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Meningitis occurs most often in children under five years of age and in people living in crowded conditions such as those found in the military or in institutions. In older patients, meningococcal bacteria are a more likely cause than strep. The symptoms are varied and may include sore throat; stiff neck; a sudden, spiking fever; intense headache; chills; muscle pain in the back and legs; racing heart; and a rash. As many as 20 percent of all cases evolve into a severe form of meningitis marked by extreme prostration, intravascular coagulation, skin lesions, and shock. Left untreated, this particular infection may cause respiratory or heart failure and be fatal in just six to 24 hours.
Meningitis must be treated immediately with large doses of penicillin G, ampicillin, or a cephalosporin, such as ceftriaxone or cefotaxime.
Tetanus
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People get tetanus (lockjaw) when a puncture wound becomes contaminated by soil, dust, or animal feces. The incubation period ranges from less than two days in severe cases to three or four weeks in milder cases.
Symptoms include spasms and increased muscle tone near the wound, profuse sweating, and a low-grade fever. Patients also experience an extreme tightening of neck and facial muscles, which produces a grotesque grinning expression; rigidity of abdominal and back muscles; and convulsions.
Treatment must begin within 72 hours after a puncture wound occurs. Patients who have no previous immunization need tetanus immune globulin or tetanus antitoxin for temporary protection, followed by immunization with tetanus toxoid. Those who have not been immunized in the past five years need a booster shot of tetanus toxoid. If tetanus develops, treatment consists of airway maintenance and the use of muscle relaxants, such as diazepam (Valium), or a neuromuscular blocker. High doses of antibiotics (preferably penicillin) are also necessary.
Intestinal Infections
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Salmonella is an extremely common infection--more than two million new cases are reported in the United States each year. Salmonella bacteria are the cause of typhoid fever, and are often the culprits in gastroenteritis (inflammation of the stomach and intestines). Occasionally, they cause blood poisoning and localized infection.
Gastroenteritis caused by salmonella is usually contracted by eating contaminated or inadequately processed foods--especially eggs, turkey, duck, and chicken. Other sources include contaminated dry milk, chocolate bars, and contact with infected animals or people. Symptoms typically include diarrhea, nausea, abdominal pain, and fever. Though the infection usually clears up on its own, at times it may progress to intervals of high fever, abscesses, dehydration, and blood poisoning. Treatment for uncomplicated cases includes bed rest and fluid and electrolyte replacement.
Typhoid fever is usually contracted by drinking contaminated water, takes three weeks to run its course, and is marked by persistent fever and flu-like symptoms. For this infection, a wide variety of antibiotics may be prescribed.
Infections by Escherichia coli and other bacteria living in human intestines cause a great deal of diarrheal illness in American children. These infections are also prevalent among travelers to other countries--particularly those visiting Mexico, South America, and Southeast Asia. People with mild infections recover easily. Those with severe infections, however, require prompt fluid and electrolyte replacement to prevent fatal dehydration. This cautious course is especially important for children, who are highly susceptible to dehydration.
Symptoms include the sudden onset of watery diarrhea, abdominal pain, and cramping. Some forms may produce chills, along with blood and pus in the stools. In small children, the stools may be yellow or green, and the child may experience vomiting, irritability, loss of appetite, and listlessness, possibly progressing to severe dehydration, fever, and shock.
Treatment includes rest and correction of fluid and electrolyte imbalances. Intravenous antibiotics are occasionally needed to treat infections in infants.
Lyme disease
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Lyme disease is contracted from the bite of an infected deer tick. A red, enlarging ring is the first sign of infection. This mark may be itchy, but usually causes no irritation. Several days later, a few more lesions may turn up. The blotches last several weeks, and within a few days of their appearance may be joined by a variety of other symptoms including stiff neck, malaise, fatigue, chills, fever, headache, achiness, and muscle pain. Stage two occurs weeks or months later and may include cardiac and neurologic symptoms such as facial palsy. These symptoms may last for months or become chronic. Stage three can begin weeks or years later and is marked by chronic arthritis-like symptoms.
Early treatment may prevent later complications. The usual treatment for adults is a 10- to 20-day course of oral doxycycline or tetracycline, although penicillin, amoxicillin, or cephalosporins may be used instead. Children under eight years of age usually receive oral penicillin or amoxicillin. In advanced stages of the disease, intravenous penicillin or ceftriaxone may be given for two to four weeks.
The list of infectious diseases goes on--diphtheria, listeriosis, botulism, gas gangrene, actinomycosis, dysentery, cholera, poliomyelitis, Colorado tick fever, Rocky Mountain spotted fever, malaria, giardiasis, trichinosis, hookworm--but, happily, most are either rare in this country or easily preventable. If we take full advantage of the immunization measures and advanced antibiotics available today, we now have less to fear than ever before in history.
