TABLE 94.2 CLINICAL AND LABORATORY PREDICTORS OF SERIOUS BACTERIAL INFECTION Toxic Shock Syndrome Toxic shock syndrome (TSS) is characterized by severe, prolonged shock and is caused by toxins produced by S aureus or GAS TSS presents with the sudden onset of high fever, vomiting, and watery diarrhea Pharyngitis, headache, and myalgias may also occur, and oliguria rapidly develops Within 48 hours, the disease progresses to hypotensive shock The patient has a fever, usually 39° to 41°C (102.2° to 105.8°F); a diffuse, erythematous maculopapular rash; and hyperemia of the mucous membranes In almost one-half of cases of streptococcal TSS, no portal of entry is identified, or only minor, nonpenetrating skin trauma is identified in retrospect The Centers for Disease Control and Prevention (CDC) definitions of TSS are described in e-Table 94.1 Laboratory findings include leukocytosis with a left shift, thrombocytopenia, transaminitis, elevated creatinine, elevated creatinine kinase, myoglobinuria, and coagulopathy Complications can include acute respiratory distress syndrome (seen in over one-half of patients), acute kidney injury occurs in almost all children (creatinine elevation precedes hypotension), and disseminated intravascular coagulation The initial diagnosis is clinical The following laboratory tests should be obtained from all children suspected of having TSS: CBC, platelet count, PT, PTT, D dimer, electrolytes, blood urea nitrogen (BUN), creatinine, AST, alanine aminotransferase (ALT), and creatinine kinase Cultures of the blood, urine, stool, throat, and vagina serve to isolate S aureus and to rule out other infectious causes of shock A lumbar puncture (LP) is often required to exclude bacterial meningitis, assuming a child is not unstable or coagulopathic The management of TSS is the same as that for shock caused by other organisms (see Chapter 10 Shock ) Broad-spectrum antibiotics (vancomycin and ceftriaxone) are indicated for patients who are hemodynamically unstable, while those who are less ill may have treatment limited to an antistaphylococcal agent Many authorities recommend the addition of clindamycin, which inhibits the toxin Rickettsial Diseases The most severe endemic rickettsial disease in the United States is RMSF, caused by Rickettsia rickettsii Transmitted by dog and wood ticks, RMSF is found in the southeastern United States and most cases present during the spring and summer months Fever, headache, and a rash are considered the characteristic triad of RMSF, but are found in only 60% of cases The rash begins as a maculopapular rash on the wrist and ankles and progresses centrally, later becoming petechial Laboratory findings include thrombocytopenia, hyponatremia, and transaminitis Multisystem involvement is seen with this systemic vasculitic condition, and the high mortality rate (up to 80% in untreated patients) usually is attributable to disseminated intravascular coagulation and shock As a consequence, treatment with doxycycline should begin immediately if RMSF is suspected, without awaiting confirmatory diagnostics (acute and convalescent serologies) Doxycycline use has been shown to decrease