1
NR511 Final Exam
Study Guide
See Midterm and Week 1 Study Guide for content covering weeks 1, 2 & 3
Common Infections
1. Impetigo
Impetigo iis ia isuperficial ibacterial iinfection iof ithe iskin. It is classified into primary impetigo
when there is a direct bacterial invasion of previously normal skin or secondaryimpetigo
when the infection arises at sites of minor skin trauma. The occurrence of secondary
impetigo is referred to as impetiginization.
Impetigo iis imost ifrequently iobserved iin ichildren iages i2–5 iyears iof iage, although older
children of any age and adults may also be affected. The infection usually occurs in
warm, humid conditions and is i easily ispread iamong iindividuals iin iclose icontact. iRisk
ifactors iinclude ipoverty, i crowding, ipoor ihygiene, iand iunderlying i scabies.
Impetigo is i primarily icaused iby iS. iaureus. iGroup iA iStreptococcus i(GAS) causes a
minority of cases, either alone or in combination with S. aureus. Occasionally, iMRSA 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 i papules ithat
iprogress ito ivesicles surrounded by erythema. Within a week, the papules
eventually become pustules that enlarge, break down, and form thick, adherent
icrusts iwith ia icharacteristic igolden iappearance. iLesions iusually iinvolve ithe iface
iand iextremities. Regional lymphadenitis may occur, although systemic symptoms
are usually absent.
Page 1 of 74
,2
• Bullous impetigo—Bullous impetigo is seen primarily in young children in which the
ivesicles ienlarge ito iform iflaccid ibullae iwith iclear iyellow ifluid , which later becomes
darker and ruptures, leaving a i thin ibrown icrust. iThe itrunk iis imore ifrequently
iaffected. 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 i ulcerative iform iin iwhich ithe ilesions
iextend ithrough ithe iepidermis iand ideep iinto ithe idermis. Ecthyma iresembles
i"punched-out" iulcers covered with yellow crust surrounded by raised violaceous
margins.
Page 2 of 74
,3
Poststreptococcal iglomerulonephritis iis ia iserious icomplication iof iimpetigo i(ecthyma).
This condition develops within 1–2 weeks following infection. Poststreptococcal
glomerulonephritis manifests with iedema, ihypertension, ifever, iand ihematuria.
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 ishould
ialways i be itreated i with ioral itherapy.
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 cephalexin are appropriate treatments. A 7-day course of oral antibiotic treatment is
recommended. If only streptococci are detected in extensive impetigo or ecthyma, oral
penicillin is the preferred therapy.
MRSA iimpetigo ican ibe itreated iwith idoxycycline, iclindamycin, ior itrimethoprim-
sulfamethoxazole
i i(Bactrim). Crusted lesions can be washed gently. Children can return
to school 24 hours after beginning an effective antimicrobial therapy. Draining lesions
should be kept covered.
Quiz: Sally, aged 25, presents with impetigo that has been diagnosed as infected with
staphylococcus. The clinical presentation is pruritic tender, red vesicles surrounded
by erythema with a rash that is ulcerating. She has not been adequatelytreated
recently. Which type of impetigo is this?
a. Bullous impetigo
b. Staphylococcal scalded skin syndrome (SSSS)
c. Nonbullous impetigo
id. iEcthyma
2. Staphylococcal Scalded Skin Syndrome
Caused by Staphylococcus aureus, it’s a variant of bullous impetigo:Epidermal necrosis
caused by bacterial exotoxins, resulting in the epithelial layer peeling off in large,
sheetlike pieces; imimics iscalded-skin ithermal iburn. This serious infection is more
commonly seen in children and usually begins in the intertriginous areas.
Page 3 of 74
, 4
3. Cellulitis
Cellulitis is an acute infection as a result of bacterial entry via breaches in the skin barrier.
As the bacteria enter the subcutaneous tissues, their toxins are released whichcauses
an inflammatory response.
✓ Cellulitis and erysipelas is almost always a unilateral infection with the most
common site of infection being the lower extremities.
✓ Cellulitis involves the deeper dermis and subcutaneous fat.
✓ Cellulitis iis iobserved imost ifrequently iamong imiddle-aged iindividuals iand iolder
adults.
✓ The vast majority of pathogens associated with cellulitis are from either
Streptococcus or Staphlococcus bacteria. iThe imost icommon iare ibeta-hemolytic
istreptococci i(groups iA, i B, iC, i G, i and i F), iand i S. i aureus i (gram i+)
✓ Both erysipelas and cellulitis manifest with areas of skin erythema, edema,
warmth and pain. Fever may be present. Additional manifestations of cellulitis
and erysipelas include lymphangitis and inflammation of regional lymph nodes.
Edema surrounding the hair follicles may lead to dimpling in the skin, creating an
appearance reminiscent of an orange peel texture called "peau id'orange".
✓ Cellulitis may present with or without purulence
✓ patients with cellulitis tend to have a more indolent course with development of
localized symptoms over a few days.
✓ Many patients with cellulitis have underlying such as tinea pedis, lymphedema,
and chronic venous insufficiency. In such patients, treatment should be directed
at both the infection and the predisposing condition if modifiable.
✓ Patients with cellulitis or erysipelas in the absence of abscess or purulent
drainage should be managed with empiric antibiotic therapy. Patients with
drainable abscess should undergo incision and drainage.
I. Describe ian iappropriate iempiric iantibiotic itreatment iplan ifor icellulitis
➢ should be managed with empiric therapy for infection due to beta-hemolytic
streptococci and methicillin-susceptible Staphylococcus aureus (MSSA) with:
• Cephalexin 500 mg four times daily (alternative for mild penicillin allergy)
• Clindamycin 300 mg to 450 mg four times daily (alternative for severe penicillin
allergy)
➢ Good choices for uncomplicated cases of cellulitis that are not associated with
human or animal bites include dicloxacillin or cephalexin for 10 to 14 days.
➢ If pt has severe PCN allergy rx erythromycin
➢ If caused by animal or human bite: amoxicillin-clavulanic acid (augmentin) for 2
weeks
The coverage for MRSA is achieved by adding to amoxicillin one of the following:
Bactrim DS twice daily
Doxycycline 100 mg twice daily
Minocycline 200 mg orally once, then 100 mg orally every 12 hoursIf
clindamycin is used, no additional MRSA coverage is needed.
Page 4 of 74
NR511 Final Exam
Study Guide
See Midterm and Week 1 Study Guide for content covering weeks 1, 2 & 3
Common Infections
1. Impetigo
Impetigo iis ia isuperficial ibacterial iinfection iof ithe iskin. It is classified into primary impetigo
when there is a direct bacterial invasion of previously normal skin or secondaryimpetigo
when the infection arises at sites of minor skin trauma. The occurrence of secondary
impetigo is referred to as impetiginization.
Impetigo iis imost ifrequently iobserved iin ichildren iages i2–5 iyears iof iage, although older
children of any age and adults may also be affected. The infection usually occurs in
warm, humid conditions and is i easily ispread iamong iindividuals iin iclose icontact. iRisk
ifactors iinclude ipoverty, i crowding, ipoor ihygiene, iand iunderlying i scabies.
Impetigo is i primarily icaused iby iS. iaureus. iGroup iA iStreptococcus i(GAS) causes a
minority of cases, either alone or in combination with S. aureus. Occasionally, iMRSA 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 i papules ithat
iprogress ito ivesicles surrounded by erythema. Within a week, the papules
eventually become pustules that enlarge, break down, and form thick, adherent
icrusts iwith ia icharacteristic igolden iappearance. iLesions iusually iinvolve ithe iface
iand iextremities. Regional lymphadenitis may occur, although systemic symptoms
are usually absent.
Page 1 of 74
,2
• Bullous impetigo—Bullous impetigo is seen primarily in young children in which the
ivesicles ienlarge ito iform iflaccid ibullae iwith iclear iyellow ifluid , which later becomes
darker and ruptures, leaving a i thin ibrown icrust. iThe itrunk iis imore ifrequently
iaffected. 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 i ulcerative iform iin iwhich ithe ilesions
iextend ithrough ithe iepidermis iand ideep iinto ithe idermis. Ecthyma iresembles
i"punched-out" iulcers covered with yellow crust surrounded by raised violaceous
margins.
Page 2 of 74
,3
Poststreptococcal iglomerulonephritis iis ia iserious icomplication iof iimpetigo i(ecthyma).
This condition develops within 1–2 weeks following infection. Poststreptococcal
glomerulonephritis manifests with iedema, ihypertension, ifever, iand ihematuria.
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 ishould
ialways i be itreated i with ioral itherapy.
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 cephalexin are appropriate treatments. A 7-day course of oral antibiotic treatment is
recommended. If only streptococci are detected in extensive impetigo or ecthyma, oral
penicillin is the preferred therapy.
MRSA iimpetigo ican ibe itreated iwith idoxycycline, iclindamycin, ior itrimethoprim-
sulfamethoxazole
i i(Bactrim). Crusted lesions can be washed gently. Children can return
to school 24 hours after beginning an effective antimicrobial therapy. Draining lesions
should be kept covered.
Quiz: Sally, aged 25, presents with impetigo that has been diagnosed as infected with
staphylococcus. The clinical presentation is pruritic tender, red vesicles surrounded
by erythema with a rash that is ulcerating. She has not been adequatelytreated
recently. Which type of impetigo is this?
a. Bullous impetigo
b. Staphylococcal scalded skin syndrome (SSSS)
c. Nonbullous impetigo
id. iEcthyma
2. Staphylococcal Scalded Skin Syndrome
Caused by Staphylococcus aureus, it’s a variant of bullous impetigo:Epidermal necrosis
caused by bacterial exotoxins, resulting in the epithelial layer peeling off in large,
sheetlike pieces; imimics iscalded-skin ithermal iburn. This serious infection is more
commonly seen in children and usually begins in the intertriginous areas.
Page 3 of 74
, 4
3. Cellulitis
Cellulitis is an acute infection as a result of bacterial entry via breaches in the skin barrier.
As the bacteria enter the subcutaneous tissues, their toxins are released whichcauses
an inflammatory response.
✓ Cellulitis and erysipelas is almost always a unilateral infection with the most
common site of infection being the lower extremities.
✓ Cellulitis involves the deeper dermis and subcutaneous fat.
✓ Cellulitis iis iobserved imost ifrequently iamong imiddle-aged iindividuals iand iolder
adults.
✓ The vast majority of pathogens associated with cellulitis are from either
Streptococcus or Staphlococcus bacteria. iThe imost icommon iare ibeta-hemolytic
istreptococci i(groups iA, i B, iC, i G, i and i F), iand i S. i aureus i (gram i+)
✓ Both erysipelas and cellulitis manifest with areas of skin erythema, edema,
warmth and pain. Fever may be present. Additional manifestations of cellulitis
and erysipelas include lymphangitis and inflammation of regional lymph nodes.
Edema surrounding the hair follicles may lead to dimpling in the skin, creating an
appearance reminiscent of an orange peel texture called "peau id'orange".
✓ Cellulitis may present with or without purulence
✓ patients with cellulitis tend to have a more indolent course with development of
localized symptoms over a few days.
✓ Many patients with cellulitis have underlying such as tinea pedis, lymphedema,
and chronic venous insufficiency. In such patients, treatment should be directed
at both the infection and the predisposing condition if modifiable.
✓ Patients with cellulitis or erysipelas in the absence of abscess or purulent
drainage should be managed with empiric antibiotic therapy. Patients with
drainable abscess should undergo incision and drainage.
I. Describe ian iappropriate iempiric iantibiotic itreatment iplan ifor icellulitis
➢ should be managed with empiric therapy for infection due to beta-hemolytic
streptococci and methicillin-susceptible Staphylococcus aureus (MSSA) with:
• Cephalexin 500 mg four times daily (alternative for mild penicillin allergy)
• Clindamycin 300 mg to 450 mg four times daily (alternative for severe penicillin
allergy)
➢ Good choices for uncomplicated cases of cellulitis that are not associated with
human or animal bites include dicloxacillin or cephalexin for 10 to 14 days.
➢ If pt has severe PCN allergy rx erythromycin
➢ If caused by animal or human bite: amoxicillin-clavulanic acid (augmentin) for 2
weeks
The coverage for MRSA is achieved by adding to amoxicillin one of the following:
Bactrim DS twice daily
Doxycycline 100 mg twice daily
Minocycline 200 mg orally once, then 100 mg orally every 12 hoursIf
clindamycin is used, no additional MRSA coverage is needed.
Page 4 of 74
