Chapter 130. Streptococcal and Enterococcal Infections (Part 8)

Deep Soft-Tissue Infections: TreatmentOnce necrotizing fasciitis is suspected, early surgical exploration is both diagnostically and therapeutically indicated. Surgery reveals necrosis and inflammatory fluid tracking along the fascial planes above and between muscle groups, without involvement of the muscles themselves. The process usually extends beyond the area of clinical involvement, and extensive debridement is required. Drainage and debridement are central to the management of necrotizing fasciitis; antibiotic treatment is a useful adjunct (Table 130-3), but surgery is lifesaving.Treatment for streptococcal myositis consists of surgical drainage—usually by an open procedure that permits evaluation of the extent of infection and ensuresadequate debridement...
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Chapter 130. Streptococcal and Enterococcal Infections (Part 8) Chapter 130. Streptococcal and Enterococcal Infections (Part 8) Deep Soft-Tissue Infections: Treatment Once necrotizing fasciitis is suspected, early surgical exploration is bothdiagnostically and therapeutically indicated. Surgery reveals necrosis andinflammatory fluid tracking along the fascial planes above and between musclegroups, without involvement of the muscles themselves. The process usuallyextends beyond the area of clinical involvement, and extensive debridement isrequired. Drainage and debridement are central to the management of necrotizingfasciitis; antibiotic treatment is a useful adjunct (Table 130-3), but surgery is life-saving. Treatment for streptococcal myositis consists of surgical drainage—usuallyby an open procedure that permits evaluation of the extent of infection and ensuresadequate debridement of involved tissues—and high-dose penicillin (Table 130-3). Pneumonia and Empyema GAS is an occasional cause of pneumonia, generally in previously healthyindividuals. The onset of symptoms may be abrupt or gradual. Pleuritic chest pain,fever, chills, and dyspnea are the characteristic manifestations. Cough is usuallypresent but may not be prominent. Approximately one-half of patients with GASpneumonia have an accompanying pleural effusion. In contrast to the sterileparapneumonic effusions typical of pneumococcal pneumonia, those complicatingstreptococcal pneumonia are almost always infected. The empyema fluid isusually visible by chest radiography on initial presentation, and its volume mayincrease rapidly. These pleural collections should be drained early, as they tend tobecome loculated rapidly, resulting in a chronic fibrotic reaction that may requirethoracotomy for removal. Bacteremia, Puerperal Sepsis, and Streptococcal Toxic ShockSyndrome GAS bacteremia is usually associated with an identifiable local infection.Bacteremia occurs rarely with otherwise uncomplicated pharyngitis, occasionallywith cellulitis or pneumonia, and relatively frequently with necrotizing fasciitis.Bacteremia without an identified source raises the possibility of endocarditis, anoccult abscess, or osteomyelitis. A variety of focal infections may arisesecondarily from streptococcal bacteremia, including endocarditis, meningitis,septic arthritis, osteomyelitis, peritonitis, and visceral abscesses. GAS is occasionally implicated in infectious complications of childbirth,usually endometritis and associated bacteremia. In the preantibiotic era, puerperalsepsis was commonly caused by GAS; currently, it is more often caused by GBS.Several nosocomial outbreaks of puerperal GAS infection have been traced to anasymptomatic carrier, usually someone present at delivery. The site of carriagemay be the skin, throat, anus, or vagina. Beginning in the late 1980s, several reports described patients with GASinfections associated with shock and multisystem organ failure. This syndromewas called the streptococcal toxic shock syndrome (TSS) because it shares certainfeatures with staphylococcal TSS. In 1993, a case definition for streptococcal TSSwas formulated (Table 130-4). The general features of the illness include fever,hypotension, renal impairment, and respiratory distress syndrome. Various typesof rash have been described, but rash usually does not develop. Laboratoryabnormalities include a marked shift to the left in the white blood cell differential,with many immature granulocytes; hypocalcemia; hypoalbuminemia; andthrombocytopenia, which usually becomes more pronounced on the second orthird day of illness. In contrast to patients with staphylococcal TSS, the majoritywith streptococcal TSS are bacteremic. The most common associated infection is asoft tissue infection—necrotizing fasciitis, myositis, or cellulitis—although avariety of other associated local infections have been described, includingpneumonia, peritonitis, osteomyelitis, and myometritis. Streptococcal TSS isassociated with a mortality rate of ≥30%, with most deaths secondary to shock andrespiratory failure. Because of its rapidly progressive and lethal course, earlyrecognition of the syndrome is essential. Patients should receive aggressivesupportive care (fluid resuscitation, pressors, and mechanical ventilation) inaddition to antimicrobial therapy and, in cases associated with necrotizing fasciitis,surgical debridement. Exactly why certain patients develop this fulminantsyndrome is not known. Early studies of the streptococcal strains isolated fromthese patients demonstrated a strong association with the production of pyrogenicexotoxin A. This association has been inconsistent in subsequent case series.Pyrogenic exotoxin A and several other streptococcal exotoxins act assuperantigens to trigger release of inflammatory cytokines from T lymphocytes.Fever, shock, and organ dysfunction in streptococcal TSS may reflect, in part, thesystemic effects of superantigen-mediated cytokine release. Table 130-4 Proposed Case Definition for the Streptococcal ToxicShock Syndromea I. Isolation of group A streptococci (Streptococcus pyogenes) A. From a normally sterile site B. From a nonsterile site II. Clinical signs of severity A. Hypotension and B. ≥2 of the following signs 1. Renal impairment 2. Coagulopathy 3. Liver function impairment 4. Adult respiratory distress syndrome 5. A generalized erythematous macular rash that may desquamate 6. Soft tissue necrosis, including necrotizing fasciitis or myositis; organgrene a An illness fulfilling criteria IA, IIA, and IIB ...