NR 511
Gh
NR 511 FINAL EXAM STUDY GUIDE
GRADED A+
, NR 511 FINAL EXAM STUDY GUIDE
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.
,• Bullous impetigo—Bullous impetigo is seen primarily in
young children in which the vesicles enlarge to form flaccid
bullae with clear yellow fluid, which later becomes darker and
ruptures, leaving a thin brown crust. The trunk is more
frequently affected. Bullous impetigo in an adult with
appropriate demographic risk factors should prompt an
investigation for previously undiagnosed human
immunodeficiency virus (HIV) infection.
• Ecthyma—This form of impetigo, caused by group A, beta-
hemolytic Streptococcus (Streptococcus pyogenes), consists of
an ulcerative form in which the lesions extend through the
epidermis and deep into the dermis. Ecthyma resembles
"punched-out" ulcers covered with yellow crust surrounded by
raised violaceous margins.
, Poststreptococcal glomerulonephritis is a serious complication of
impetigo (ecthyma). This condition develops within 1–2 weeks
following infection. Poststreptococcal glomerulonephritis
manifests with edema, hypertension, fever, and hematuria.
The diagnosis of impetigo often can be made on the basis of
clinical manifestations.
A Gram stain and culture of pus or exudate is recommended to
identify whether S. aureus and/or a beta-hemolytic Streptococcus is
the cause. However, treatment may be initiated without these
studies in patients with typical clinical presentations.
Bullous and nonbullous impetigo can be treated with either topical
or oral therapy. Topical therapy is used for patients with limited
skin involvement whereas oral therapy is recommended for
patients with numerous lesions. Unlike impetigo, ecthyma should
always be treated with oral therapy.
Benefits of topical therapy include fewer side effects and lower
risk for contributing to bacterial resistance compared with oral
therapy. Topical choices to treat impetigo include the following
medications for 5 days.
• Mupirocin three times daily
• Retapamulin twice daily
Extensive impetigo and ecthyma should be treated with an
antibiotic effective for both S. aureus and streptococcal infections
unless cultures reveal only streptococci. Dicloxacillin and
Gh
NR 511 FINAL EXAM STUDY GUIDE
GRADED A+
, NR 511 FINAL EXAM STUDY GUIDE
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.
,• Bullous impetigo—Bullous impetigo is seen primarily in
young children in which the vesicles enlarge to form flaccid
bullae with clear yellow fluid, which later becomes darker and
ruptures, leaving a thin brown crust. The trunk is more
frequently affected. Bullous impetigo in an adult with
appropriate demographic risk factors should prompt an
investigation for previously undiagnosed human
immunodeficiency virus (HIV) infection.
• Ecthyma—This form of impetigo, caused by group A, beta-
hemolytic Streptococcus (Streptococcus pyogenes), consists of
an ulcerative form in which the lesions extend through the
epidermis and deep into the dermis. Ecthyma resembles
"punched-out" ulcers covered with yellow crust surrounded by
raised violaceous margins.
, Poststreptococcal glomerulonephritis is a serious complication of
impetigo (ecthyma). This condition develops within 1–2 weeks
following infection. Poststreptococcal glomerulonephritis
manifests with edema, hypertension, fever, and hematuria.
The diagnosis of impetigo often can be made on the basis of
clinical manifestations.
A Gram stain and culture of pus or exudate is recommended to
identify whether S. aureus and/or a beta-hemolytic Streptococcus is
the cause. However, treatment may be initiated without these
studies in patients with typical clinical presentations.
Bullous and nonbullous impetigo can be treated with either topical
or oral therapy. Topical therapy is used for patients with limited
skin involvement whereas oral therapy is recommended for
patients with numerous lesions. Unlike impetigo, ecthyma should
always be treated with oral therapy.
Benefits of topical therapy include fewer side effects and lower
risk for contributing to bacterial resistance compared with oral
therapy. Topical choices to treat impetigo include the following
medications for 5 days.
• Mupirocin three times daily
• Retapamulin twice daily
Extensive impetigo and ecthyma should be treated with an
antibiotic effective for both S. aureus and streptococcal infections
unless cultures reveal only streptococci. Dicloxacillin and
