23 - 150 - SUPERFICIAL CUTANEOUS INFECTIONS AND PYODERMAS Flashcards
most common cause of superficial purulent skin infections (pyodermas)
S. AUREUS
Pitted keratolysis is caused by what organisms?
Kytococcus sedentarius,
Dermatophilus congolensis
Corynebacterium spp.,
Erythrasma is caused by which organism
Corynebacterium minutissimum
Trichobacteriosis is caused by which oranism?
Cornebacterium spp.
S. Aureus is found permanently colonized in the anterior nares in approximately how many percent of individuals?
30%
Approximately ______% of healthy individuals are intermittent carriers of S. aureus at some site in the skin or mucosa
60%
most frequent cause of SSTIs that present to emergency departments
Community-acquired MRSA (CA-MRSA)
Where are the Sites of Colonization (Carrier State). Of S. Aureus
Sites of Colonization (Carrier State)
■ Anterior nares
■ Throat
■ Axillae, perineum
■ Hands
■ Involved skin in individuals with atopic dermatitis
Sites of Colonization of S. Aureus in Neonates (and Sites of Infection)
Sites of Colonization in Neonates (and Sites of Infection)
■ Skin
■ Umbilicus
■ Circumcision site
■ Conjunctivae
major risk factor for postoperative surgical wound infections
Nasal carriage of S. aureus
Staphylococcus aureus: impetigo. Erythema and honey-colored crusting on the nose and upper lip area (A), which can spread to involve the entire centrofacial region
Causative agent of nonbullous impetigo
S. aureus (most commonly), or GAS, or both in combination
bullous impetigo is cause by?
S. aureus strains that express certain exfoliative toxins that cleave desmoglein 1 in the epidermis, resulting in clusters of thin-roofed bullae, vesicles, and/or pustules
What protein in the epidermis is cleaved by exfoliative toxins in bullous impetigo?
DESMOGLEIN 1
T/F. Nikolsky sign is positive in bullous impetigo
False
Bullae usually arise on areas of grossly normal skin. The Nikolsky sign (sheet-like removal of epidermis by shearing pressure) is not present.
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represents superinfection of varicella lesions by S. aureus strains that express exfoliative toxins (bullous impetiginization).
bullous varicella
Ecthyma can be caused by what organisms
S. Aureus and/or GAS
Superficial folliculitis is also called
Follicular or Bockhart impetigo
secondary infection of miliaria of neonates by S. aureus
Periporitis staphylogenes
S. aureus infection of the eyelids, presenting with scaling or crusting of the eyelid margins, often with associated conjunctivitis
Staphylococcal blepharitis
deep folliculitis with perifollicular inflammation occurring in the bearded areas of the face and upper lip
Sycosis barbae
deep, chronic form of sycosis barbae associated with scarring, usually occurring as a circinate lesion
Lupoid sycosis
A central cicatrix surrounded by pustules and papules gives the appearance of lupus vulgaris
Pseudofolliculitis barbae. Multiple papules in the lower beard area caused by ingrowing of the curved hair shaft in a black man who shaves. If pustules are present, secondary Staphylococcus aureus infection must be ruled out.
How can you differentiate dermatophytic folliculitis from S. Aureus folliculitis?
In fungal infections, hairs are usually broken or loosened, and there are suppurative or granulomatous nodules rather than pustules. Also, in dermatophytic folliculitis, plucking of hairs is usually painless (see Chap. 160).
deep-seated inflammatory nodule that develops around a hair follicle, usually from a preceding, more superficial folliculitis and often evolves into an abscess.
Furuncle
A furuncle starts as a hard, tender, red folliculocentric nodule in hair-bearing skin that enlarges and becomes painful and fluctuant after several days (ie, undergoes abscess formation; Fig. 150-8A).
more extensive, deeper, communicating, infiltrated, and serious inflammatory lesion that develops when suppuration occurs in thick inelastic skin when multiple, closely set furuncles coalesce
Carbuncle
A carbuncle characteristically presents as an extremely painful lesion at the nape of the neck, the back, or thighs (Fig. 150-9). Fever and malaise are often present, and the patient may appear quite ill. The involved area is red and indurated, and multiple pustules soon appear on the surface, draining externally around multiple hair follicles. The lesion soon develops a yellow-gray irregular crater at the center, which may then heal slowly by granulating
major infectious cause of acute paronychia
S aureus
chronic or recurrent paronychia is usually caused by?
Candida albicans
Pag acute? S. Aureus!
purulent infection or abscess involving the bulbous distal end of a finger
Staphylococcal Whitlow (Felon)
Whitlow or felon can be caused by what organisms?
S. Aureus
Herpes simplex virus
How can you differentiate Staphilococcal whitlow and herpetic whitlow?
The portal of entry of S. aureus is a traumatic injury or possible extension of an acute paronychia. This infection is usually very painful. An obvious portal of entry is often apparent. The finger bulb is red, hot, tender, and edematous, with possible abscess formation
In contrast, individuals with herpetic whitlows usually have a history of lesions occurring in the same site and present with grouped hemorrhagic vesicles, which may become confluent and form a single bulla
Criteria for systemic inflammatory response syndrome (SIRS)
Sa fitz, RR of > 24 nakalagay pero other sources say more than 20 lang
“systemic inflammatory response syndrome, which includes temperature higher than 38°C (100.4°F) or lower than 36°C (96.8°F), tachypnea exceeding 24 breaths per minute, tachycardia exceeding 90 beats per minute, or white blood cell count higher than 12,000 or less than 400 cells/µL”
Bullous impetigo is caused certain types of exfoliative toxins _____
ETA, ETB, and ETD [ETC has no activity in humans]
Walang C!
Exfoliative toxins in bullous impetigo target which desmosoal cadherin?
DESMOGLEIN 1!
Recall: which AIBD have the same target of autoantibodies?
P. Foliaceus!!
toxin largely responsible for S. aureus toxic shock syndrome
TSST-1
Because S. aureus isolates from impetigo, ecthyma and folliculitis are more frequently caused by methicillin-sensitive S. aureus, which antibiotics re recommended?
- dicloxacillin (or similar penicillinase-resistant semisynthetic penicillin) (adults: 250 to 500 mg orally 4 times a day; not typically used in children)
- cephalexin (adults: 500 mg orally 4 times a day; children 50 to 100 mg/kg/day divided 3 to 4 times per day)
In general, oral antibiotic treatment should be continued for how many days?
How many days if streptococci is isolated?
7 days (10 days if strep is isolated)
For patients allergic to penicillin or β-lactams, which antibiotic is appropriae?
erythromycin could serve as a substitute (adults: 250 to 500 mg orally 4 times a day; children: 40 mg/kg/day divided 3 to 4 times per day).
If CA-MRSA is suspected as the causative organism, which antibiotics are suitable?
- doxycycline (adults: 100 mg twice daily; children: not recommended for children younger than age 8 years),
2.clindamycin (adults: 300 to 450 mg 3 to 4 times a day; children: 20 to 40 mg/kg/day in divided doses)
- TMP-SMX (1 double-strength tablet twice daily; children: 8 to 12 mg/kg/day [trimethoprim component] divided 2 times per day) are recommended for initial empiric therapy, but the choice of antibiotic might need to be changed based on the clinical response and antibiotic sensitivity results
tetracyclines (including doxycycline) should not be used in children younger than??
What options can you give to children ?
8 years old!
clindamycin and TMP-SMX were equally and highly effective for uncomplicated SSTIs in pediatric patients
In cases of recurrent S. aureus SSTIs despite appropriate treatment and the aforementioned personal and environmental hygienic measures, decolonization of the patients can be attempted.
how do you do this?
- Nasal decolonization of S. aureus can be achieved with mupirocin ointment administered to the nares twice daily for 5 to 10 days along with body decolonization with either daily chlorhexidine cleansing solution for 5 to 14 days or bleach baths.
- The nares and body decolonization procedures can be repeated on a monthly basis for 3 months.
- A typical regimen for bleach baths is 1 teaspoon of bleach per 1 gallon of water or one-quarter cup of bleach per one-quarter bathtub of water (approximately 13 gallons of water) and can be performed for 15 minutes twice weekly for 3 months.
If decolonization measures are ineffective, oral antibiotic treatment according to the treatment regimens above could be used in conjunction with addition of which antibiotic?
rifampin (typically 300 mg twice daily)
most common cause of bacterial pharyngitis (ie, “strep throat”)
Group A Streptococcus (ie, Streptococcus pyogenes)
Sites of Colonization (Carrier State) of GAS
Sites of Colonization (Carrier State)
■ Nasopharyngeal mucosa
■ Upper airways
■ Skin
After a GAS infection, immunologic-mediated diseases may ensue such as?
guttate psoriasis, acute rheumatic fever, rheumatic heart disease, and glomerulonephritis
major source of GAS transmission is from
respiratory droplets from patients with infections or colonization in the upper respiratory tract
What do you call a large, tense blister filled with seropurulent fluid, over the volar skin pad of distal fingers or toes?
blistering distal dactylitis, also called bulla repens
How can you differentiate superficial thrombophlebitis from acute lymphangitis?
The absence of a portal of entry and of tender regional adenopathy is helpful in distinguishing superficial thrombophlebitis from acute lymphangitis
Poststreptococcal glomerulonephritis typically occurs how many weeks following GAS pharyngitis?
1 to 3 weeks
Poststreptococcal glomerulonephritis typically occurs how many weeks following GAS impetigo?
3 to 6 weeks
Acute rheumatic fever occurs in less than 1% of patients with a GAS infection, and typically occurs how many weeks following a GAS pharyngitis infection
2 weeks
high antistreptolysin O titers are more common after GAS pharyngitis or skin infection?
GAS pharyngitis
high ASO - pharyngitis
ASOre throat
high antideoxyribonuclease B titers are more common following GAS pharyngitis or skin infection?
GAS skin infections
In general, skin biopsies are not typically performed in uncomplicated cases of impetigo, ecthyma, intertriginous infections, blistering distal dactylitis or acute lymphangitis.
When are biopsies recommended?
biopsies are recommended in immunocompromised patients or in patients with fever and neutropenia for histologic evaluation (including microorganism staining) and microbiology cultures and antibiotic sensitivities to diagnose the pathogenic organism and to help direct appropriate antibiotic therapy.
in contrast to S. aureus, the systemic antibiotic treatment of superficial pyodermas (eg, impetigo, ecthyma, and intertrigo) known to be caused by GAS is penicillin and treatment should be continued for how many days to ensure eradication of the infection ?
10 days
patients with recurrent episodes of GAS infections can also be treated with
- 10-day course of clindamycin (adults: 300 to 450 mg twice daily; children: 20 to 30 mg/kg/day in 3 equally divided doses) or
- amoxicillin-clavulanic acid (adults: 875/125 mg twice daily; children: 40 mg/kg/day in 3 equally divided doses)
What causes the coral red fluorescence in wood lamp in patients with erythrasma
Coproporphyrin III produces by Corynebacterium minutissimum
Most common site of involvement of erythrasma
Web space of the feet, especially between the 4th and 5th toes
How can you differentiate erythrasma from dermatophytes?
patches have a relatively uniform appearance in erythrasma as compared with tinea corporis or cruris, which often have central clearing
Treatment for erythrasma
- For localized erythrasma, especially of the web spaces of the feet: benzoyl peroxide cleanser and 5% gel are effective in most cases
- Clindamycin or erythromycin (2% solution) or azole creams
- Fusidic acid has been used outside the United States.
- For widespread involvement: oral erythromycin 250 mg QID x 14 days
- Alternatives: clarithromycin 1 g single oral dose; oral tetracycline or chloramphenicol,
-secondary prophylaxis: antibacterial benzoyl peroxide cleanser when showering is effective.
bacterial infection of the hair shaft
TRICHOBACTERIOSIS
The majority of the cutaneous pyodermas are caused by what organisms?
Staphylococcus aureus or group A Streptococcus (GAS) (also known as Streptococcus pyogenes)
a common colonizer of the skin but is capable of causing superficial and invasive infections, particularly on implanted foreign materials such as surgical implants and catheters or in cases of immunosuppression
S. epidermidis
Conditions predisposing to S. aureus colonization
- atopic dermatitis,
- diabetes mellitus,
- renal insufficiency patients on dialysis,
- intravenous drug use,
- liver dysfunction, and
- certain genetic or acquired immunosuppressive disorders, including HIV infection.
bullous impetigo is caused by S. aureus strains that express what toxins?
Exfoliative Toxins (ETA, ETB, and ETD)
A small, fragile, dome-shaped pustule occurs at the infundibulum (ostium or opening) of a hair follicle, often on the scalps of children and in the beard area, axillae, extremities, and buttocks of adults.
Folliculitis
Isolated staphylococcal folliculitis is particularly common on what area?
buttocks of adults
Multiple papules in the lower beard area caused by ingrowing of the curved hair shaft in a black man who shaves
Pseudofolliculitis barbae
- rare pyogenic disease that presents as a purulent, chronic, subcutaneous infection
- Predisposing factors include trauma, immunosuppression (HIV disease, hyperimmunoglobulin E syndrome), chronic alcoholism, and diabetes mellitus.
- Lesions (usually solitary) can occur in skin, bone, and liver.
- It usually presents as a solitary lesion or a few lesions, often occurring in the genital area.
- The lesion has the gross appearance of a ruptured epidermal inclusion cyst (an erythematous circumscribed tender nodule), or prurigo nodularis
Cutaneous botryomycosis
They have the ability to **nonspecifically activate T cells **by interacting with the human leukocyte antigen–DR molecules (major histocompatibility complex II) on antigen-presenting cells and the variable region of the β subunit of the T-cell receptor without antigen present, resulting in nonspecific activation of CD4+ T cells
Superantigens
The major factor in the spread from a carrier or an infected person with GAS infection
proximity to the individual disseminating the bacteria
subpectoral abscesses and pleural effusion can develop in this presentation of GAS or S.aureus infection
- An unusual spread of GAS or S. aureus lymphangitis infection of the thumb (paronychia) or of the interdigital webs between the thumb and index finger may occur occasionally.
- Lymphatic drainage from this area can bypass the lymph nodes at the elbow and drain into the axillary nodes, which, in turn, c**ommunicate with the subpectoral nodes **and the **pleural lymphatics. **
- As a consequence, subpectoral abscesses and pleural effusion can develop.
- The subpectoral infection may dissect downward and appear over the **lower chest and upper abdomen as an area of cellulitis. **
- This is a very serious illness.
- The clinical clues to the development of this sequence of events are provided by the location of the original infection on the thumb or medial surface of the index finger and the early occurrence of axillary pain.
