Text B Streptococcal Infections

Streptococcal infections are caused by gram-posi­tive bacteria called streptococci.

The various disease-causing strains of strep­tococci are grouped by their behavior, chemistry, and appearance. Each group tends to produce specific types of infections and symptoms.

• Group A streptococci are the most virulent spe­cies for humans, who are their natural host. These streptococci can cause strep throat (a Strepto­coccal infection of the throat), tonsillitis, wound and skin infections, blood infections (septicemia), scarlet fever, pneumonia, rheumatic fever, Sydenham's chorea (St. Vitus' dance), A and kid­ney inflammation (glomerulonephritis).

• Group B streptococci most commonly cause dangerous infections in newborns (neonatal sepsis) and infections in the joints (septic arthritis) and heart (endocarditis).

• Groups C and G streptococci often are carried by animals but also grow in the human throat intestine, vagina, and skin. These streptococci can cause severe infections, including strep throat, pneumonia, skin infections, wound infec­tions, postpartum and neonatal sepsis, endocar­ditis, and septic arthritis. After an infection with one of these bacteria, kidney inflammation may develop.

• Group D streptococci and enterococci grow nor­mally in the lower digestive tract, vagina, and sur­rounding skin. They can also cause infections in wounds and in the heart valves, bladder, abdo­men, and blood.

Infections with certain types of streptococci can cause an autoimmune reaction in which the body attacks its own tissues. Such reactions may occur after an infection such as strep throat and may lead to rheumatic fever, chorea, and kid­ney damage (glomerulonephritis).

Symptoms

Streptococci may live in the respiratory tract, intestine, vagina, or elsewhere in the body with­out causing problems. Occasionally, such bacte­ria are found in an inflamed area (such as the throat or vagina) of a person who is a carrier, and the streptococci are incorrectly identified as the cause of the infection.

The most common type of streptococcal infec­tion is a throat infection (strep throat). Typically, symptoms appear suddenly and include sore throat, a general feeling of illness (malaise), chills, fever, headache, nausea, vomiting, and a rapid heartbeat. The throat is beefy red, the tonsils are swollen, and lymph nodes in the neck may be enlarged and tender. Children may have convul­sions. In children under age 4, the only symptom may be a runny nose. A cough, an inflammation of the larynx (laryngitis), and a stuffy nose are uncommon in streptococcal infections; these symptoms suggest another cause, such as a cold or allergy.

Scarlet fever is caused by streptococcal toxins that lead to a widespread, pink-red rash. The rash is most obvious on the abdomen, on the sides of the chest, and in the skinfolds. Other symptoms include a pale area around the mouth, a flushed face, an inflamed red tongue, and dark red lines in the skinfolds. The outer layer of reddened skin often peels after the fever subsides.

Streptococci also cause several types of skin infection but rarely produce abscesses. Rather, the infections tend to spread in the deep layers under the skin, producing cellulitis and some­times hot, red eruptions called erysipelas (St. An­thony's fire). Streptococci, alone or with staphylococci, also can spread along the top layers of the skin, producing scabby, crusted eruptions (impetigo).

Certain strains of streptococci may cause a rap­idly spreading and destructive infection under the skin (necrotizing fasciitis). For unknown reasons, outbreaks of this infection have become more common recently.

Diagnosis

Although symptoms may suggest a streptococ­cal infection, the diagnosis must be confirmed by tests. The best way to be certain of a streptococ­cal infection is to culture a sample from the in­fected area. After overnight growth, a culture shows characteristic bacterial colonies.

To diagnose strep throat, a culture is taken by rubbing a sterile swab over the back of the throat. The sample then is placed in a Petri dish and allowed to grow overnight. Alternatively, Group A streptococci may be detected by special, rapid tests that can produce results within a few hour's. If the result of a rapid test is positive, the slower overnight culture is not needed. Because both methods can detect streptococci in people who do not need treatment, examination by a doctor is necessary..

Treatment

People with strep throat and scarlet fever gen­erally get better in 2 weeks, even without treat­ment. Nonetheless, antibiotics can shorten the duration of symptoms in young children and pre­vent serious complications, such as rheumatic fever. They also help prevent the spread of the infection to the middle ear, sinuses, and mastoid bone as well as to other people. An antibiotic, usually oral penicillin, should be started promptly after the appearance of symptoms.

Other streptococcal infections, such as cellulitis, necrotizing fasciitis, and endocarditis, are very serious and require intravenous penicillin, sometimes together with other antibiotics. Group A streptococci are usually eliminated by penicil­lin. Some Group D streptococci, and especially enterococci, are resistant to penicillin and most antibiotics; there is no reliable antibiotic therapy available for many enterococcal strains.

Symptoms such as a fever, headache, and sore throat can be treated with drugs that reduce pain (analgesics) and fever (antipyretics), such as acetaminophen. Neither bed rest nor isolation is necessary; however, family members or friends who have similar symptoms or who have had complications from a streptococcal infection may be at risk for infection.

Notes:

Sydenham’s chorea Сиденгама хорея

malaise усталость

necrotizing fasciitis некротизирующий фасциит

convulsion судорога

flushed face покрасневшее лицо

scabby покрытый корками

strep throat стрептококовое воспаление

горла

swab тампон на палочке

Дата добавления: 2015-11-16