Chapter 130. Streptococcal and Enterococcal Infections (Part 5)

Asymptomatic Pharyngeal Colonization with Gas: TreatmentWhen a carrier is transmitting infection to others, attempts to eradicate carriage are warranted. Data are limited on the best regimen to clear GAS after penicillin alone has failed. The combination of penicillin V (500 mg four times daily for 10 days) and rifampin (600 mg twice daily for the last 4 days) has been used to eliminate pharyngeal carriage. A 10-day course of oral vancomycin (250 mg four times daily) and rifampin (600 mg twice daily) has eradicated rectal colonization.Scarlet Fever Scarlet fever consists of streptococcal infection, usually pharyngitis, accompanied by a characteristic...
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Chapter 130. Streptococcal and Enterococcal Infections (Part 5) Chapter 130. Streptococcal and Enterococcal Infections (Part 5) Asymptomatic Pharyngeal Colonization with Gas: Treatment When a carrier is transmitting infection to others, attempts to eradicatecarriage are warranted. Data are limited on the best regimen to clear GAS afterpenicillin alone has failed. The combination of penicillin V (500 mg four timesdaily for 10 days) and rifampin (600 mg twice daily for the last 4 days) has beenused to eliminate pharyngeal carriage. A 10-day course of oral vancomycin (250mg four times daily) and rifampin (600 mg twice daily) has eradicated rectalcolonization. Scarlet Fever Scarlet fever consists of streptococcal infection, usually pharyngitis,accompanied by a characteristic rash (Fig. 130-2). The rash arises from the effectsof one of three toxins, currently designated streptococcal pyrogenic exotoxins A,B, and C and previously known as erythrogenic or scarlet fever toxins. In the past,scarlet fever was thought to reflect infection of an individual lacking toxin-specificimmunity with a toxin-producing strain of GAS. Susceptibility to scarlet fever wascorrelated with results of the Dick test, in which a small amount of erythrogenictoxin injected intradermally produced local erythema in susceptible individuals butelicited no reaction in those with specific immunity. Subsequent studies havesuggested that development of the scarlet fever rash may reflect a hypersensitivityreaction requiring prior exposure to the toxin. For reasons that are not clear, scarletfever has become less common in recent years, although strains of GAS thatproduce pyrogenic exotoxins continue to be prevalent in the population. Figure 130-2 Scarlet fever exanthem. Finely punctate erythema has become confluent(scarlatiniform); petechiae can occur and have a linear configuration within theexanthem in body folds (Pastias lines). (From Fitzpatrick, Johnson, Wolff: ColorAtlas and Synopsis of Clinical Dermatology, 4th ed, New York, McGraw-Hill,2001, with permission.) The symptoms of scarlet fever are the same as those of pharyngitis alone.The rash typically begins on the first or second day of illness over the upper trunk,spreading to involve the extremities but sparing the palms and soles. The rash ismade up of minute papules, giving a characteristic sandpaper feel to the skin.Associated findings include circumoral pallor, strawberry tongue (enlargedpapillae on a coated tongue, which later may become denuded), and accentuationof the rash in skin folds (Pastias lines). Subsidence of the rash in 6–9 days isfollowed after several days by desquamation of the palms and soles. Thedifferential diagnosis of scarlet fever includes other causes of fever andgeneralized rash, such as measles and other viral exanthems, Kawasaki disease,toxic shock syndrome, and systemic allergic reactions (e.g., drug eruptions). Skin and Soft Tissue Infections GAS—and occasionally other streptococcal species—causes a variety ofinfections involving the skin, subcutaneous tissues, muscles, and fascia. Whileseveral clinical syndromes offer a useful means for classification of theseinfections, not all cases fit exactly into one category. The classic syndromes aregeneral guides to predicting the level of tissue involvement in a particular patient,the probable clinical course, and the likelihood that surgical intervention oraggressive life support will be required. Impetigo (Pyoderma) Impetigo, a superficial infection of the skin, is caused primarily by GASand occasionally by other streptococci or Staphylococcus aureus. Impetigo is seenmost often in young children, tends to occur during warmer months, and is morecommon in semitropical or tropical climates than in cooler regions. Infection ismore common among children living under conditions of poor hygiene.Prospective studies have shown that colonization of unbroken skin with GASprecedes clinical infection. Minor trauma, such as a scratch or an insect bite, maythen serve to inoculate organisms into the skin. Impetigo is best prevented,therefore, by attention to adequate hygiene. The usual sites of involvement are theface (particularly around the nose and mouth) and the legs, although lesions mayoccur at other locations. Individual lesions begin as red papules, which evolvequickly into vesicular and then pustular lesions that break down and coalesce toform characteristic honeycomb-like crusts (Fig. 130-3). Lesions are generally notpainful, and patients do not appear ill. Fever is not a feature of impetigo and, ifpresent, suggests either infection extending to deeper tissues or another diagnosis.