disease However, these children are usually not well appearing Needle aspirates from the center of the cellulitic region are positive in between 5% and 40% of cases, with punch biopsies having a higher culture yield Bedside ultrasound may allow the clinician to differentiate abscesses from cellulitis Treatment should be directed at S aureus and GAS, with empiric selection guided by the local prevalence of MRSA and past cultures While most children with cellulitis can be managed in the outpatient setting, initial parenteral therapy should be considered in the following cases: immunocompromised; toxic-appearance; rapidly progressive lesions; facial or circumferential involvement; crepitance or violaceous skin discoloration; or pain out of proportion to examination The latter two findings should prompt evaluation for necrotizing fasciitis and immediate surgical consultation Standard precautions should be used unless draining lesions exist, in which case contact precautions should be implemented Mastitis, Neonatal Mastitis is an infection of breast tissue; in neonates, it is most commonly seen in the first weeks of life and is more common in girls and in term infants The most common etiology is S aureus, but GBS, E coli, and Salmonella can also cause neonatal mastitis Infants present with unilateral painful erythema and induration of the breast bud Fever may be absent even in bacteremic children Blood cultures usually are negative; cultures of purulent drainage often are positive Empiric antibiotic coverage should include nafcillin (for coverage of GAS, GBS) and gentamicin and vancomycin if the child lives in an area with high MRSA prevalence Incision and drainage is advisable in the case of local fluctuance, with careful attention to avoiding injury to the developing breast bud, which is already at risk of damage from the infectious process and may lead to cosmetic issues of the breast first noted at adolescence Standard precautions should be used unless draining lesions exist, in which case contact precautions should be implemented Omphalitis Omphalitis is an infection of the umbilical stump and surrounding tissues The most common pathogens are S aureus and GAS; GBS (Streptococcus agalactiae ) and gram-negative enterics can also cause omphalitis The incidence has decreased in industrialized countries because of triple dye placed on the stump immediately after delivery; omphalitis usually is seen in the first 14 days of life It is more common in premature infants and in infants with complicated deliveries The first symptoms are purulent, foul-smelling drainage and later erythema around the stump (ultimately, many children have erythema that completely encircles the stump) Later manifestations include lethargy, fever or hypothermia, and irritability; late examination findings include erythema and induration of the anterior abdominal wall Minimal drainage or noncircumferential erythema is not sufficient to diagnose omphalitis, as some drainage from the umbilical stump is common in the absence of infection Evaluation for bacteremia and other systemic disease is necessary; Gram stain and cultures from umbilical drainage should be sent Empiric antibiotic coverage should include nafcillin (for coverage of GAS, GBS) and gentamicin and vancomycin if the child lives in an area with high MRSA prevalence Standard precautions should be used unless draining lesions exist, in which case contact precautions should be implemented Septic Arthritis CLINICAL PEARLS AND PITFALLS Children with septic arthritis present with joint pain (and refusal to walk, if the affected joint is in the lower extremities) and decreased range of motion Laboratory findings supportive of the diagnosis of septic arthritis include elevated inflammatory markers The definitive diagnosis is made via arthrocentesis and culture Cell count parameters allow the clinician to help differentiate between inflammatory and infectious etiologies Empiric therapy for septic arthritis outside the neonatal period should target S aureus, the most common cause of septic arthritis In Lyme-endemic regions, B burgdorferi can also cause arthritis, though the children with Lyme arthritis typically have less fulminant courses than with pyogenic arthritis Current Evidence