NR 511NR511-Final Exam Study Guide . NR511 Final Exam Study Guide See Midterm and Week 1 Study Guide for content covering weeks 1, 2 & 3

Common Infections 1. Impetigo Impetigo is a superficial bacterial infection of the skin. It is classified into primary impetigo when there is a direct bacterial invasion of previously normal skin or secondary impetigo when the infection arises at sites of minor skin trauma. The occurrence of secondary impetigo is referred to as impetiginization. Impetigo is most frequently observed in children ages 2–5 years of age, although older children of any age and adults may also be affected. The infection usually occurs in warm, humid conditions and is easily spread among individuals in close contact. Risk factors include poverty, crowding, poor hygiene, and underlying scabies. Impetigo is primarily caused by S. aureus. Group A Streptococcus (GAS) causes a minority of cases, either alone or in combination with S. aureus. Occasionally, MRSA is detected in some cases of impetigo. Variants of impetigo include nonbullous impetigo, bullous impetigo, and ecthyma. • Nonbullous impetigo—most common form of impetigo and begins as papules that progress to vesicles surrounded by erythema. Within a week, the papules eventually become pustules that enlarge, break down, and form thick, adherent crusts with a characteristic golden appearance. Lesions usually involve the face and extremities. Regional lymphadenitis may occur, although systemic symptoms are usually absent.