STIs are the most commonly reported infections in the United States and represent an important pediatric problem, particularly during infancy or adolescence This chapter focuses on HIV, syphilis, HSV outside the neonatal period, and neonatal chlamydia and gonorrheal infections and nongenital gonorrheal infections STIs causing pelvic inflammatory disease and cervicitis are covered elsewhere (Chapter 92 Gynecology Emergencies ) and management of STIs in the abused child is discussed in Chapter 87 Child Abuse/Assault In these children, the most common pathogens are Trichomonas, C trachomatis, and Neisseria gonorrhea, and one study in sexually abused girls found that 8% of girls had one or more STIs As many adolescents with one STI can be infected with more than one pathogen, identification of one STI should prompt diagnostic evaluation for others The manifestations, diagnosis, and treatment of common STIs are described in Table 94.22 Chlamydia, Neonatal C trachomatis can cause a number of syndromes in infants: conjunctivitis, trachoma, and pneumonia Chlamydia is the most common STI in the United States, and adolescent females comprise the most at-risk group Vertical transmission occurs in up to 50% of infants born to infected mothers Chlamydia conjunctivitis is characterized by a serous, slightly purulent eye discharge that can be first noticed within days to several weeks after delivery There is conjunctival injection and lid edema The drainage typically lasts to weeks Approximately 30% of children with neonatal chlamydia conjunctivitis also will have chlamydial pneumonia Chlamydia conjunctivitis and trachoma are not prevented by erythromycin that is given in the immediate newborn period to prevent ophthalmia neonatorum (see below) Trachoma is a sequela of chronic chlamydial eye infection and is characterized by corneal neovascularization which can result in blindness While rare in the United States, trachoma is the leading infectious cause of blindness globally, estimated to impact up to 80 million persons C trachomatis pneumonia occurs most commonly from weeks to months after birth and is characterized by an afebrile illness with repetitive, paroxysmal cough similar to pertussis In contrast to pertussis, leukemoid reactions are rare, but eosinophilia can be seen Upper respiratory tract symptoms are common from chlamydial colonization of the nasopharynx Radiographic findings may include hyperinflation and patchy interstitial infiltrates The diagnosis is made on the basis of direct fluorescent antibody (DFA) testing, the only FDA-approved test for the detection of C trachomatis from nasopharyngeal and conjunctival specimens The treatment of chlamydia