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Bacterial Diseases

Bacterial Diseases of the Skin

QuestionAnswer
What are the most common causes of impetigo? Staph aureus (most common) and Strep pyogenes
What is the cause of bullous impetigo? Staph aureus - the phage group II production locally
What protein is cleaved in bullous impetigo that causes the blister? desmoglein 1
What is the clinical presentation of non-bullous impetigo? -single erythematous macule that rapidly evolves into a vesicle or pustule and rapidly spreads into a "honey-colored" crust
What is the potential side effect of 5% of causes of nonbullous impetigo caused by strep pyogenes? post-strep glomerulonephritis (risk is not changed by giving antibiotics)
What patient population does bullous impetigo occur in? usually neonates
What is the histology of impetigo? -small neutrophilic vesiculopustules in the epidermis -spongiosis -intense infiltrate of neutrophils and lymphs in the upper dermis
What is the treatment of non-complicated impetigo? mupirocin retapamulin
What is the most common cause of bacterial folliculitis? Staph aureus
What is sycosis barbae? a type deep of folliculitis with large erythematous papules with a central pustule, sometimes coalescing to form pustules and crusts
How can you eradicate staph aureus nasal carriage? mupirocin ointment BID to the nares x 5-10 days
What is the most common presentation of MRSA? furuncolosis
What is the cause of methiciliin resistance in staph? altered penicillin-binding protein (PBP2a) with decreased affinity for beta-lactams
What is the D test (double-disk diffusion)? Tests for inducible resistance to clindamycin; if the "erm" gene is present, and the bug is resistant to erythromycin, then resistance to clindamycin will develop
What are the most common causes of blistering distal dactylitis? group A strep and staph aureus
Where is the location of blistering distal dactylitis? volar fat pad of the finger or toe with occasional involvement of the nail fold
What is the treatment of blistering distal dactylitis? 10 day course of antibiotics and drainage
What patient population typically gets blistering distal dactylitis? children aged 2-16 years (from nose-picking)
What is the cause of ecthyma? strep pyogenes
What are the clinical features of ecthyma? initial vesiculopustule that enlarges and develops a hemorrhagi crust with a "punched-out" appearance and necrotic base
What is the most common location of ecthyma? lower extremity
What is the cause of staph scalded skin syndrome? phage group II strains 55 and 71
What protein is cleaved in SSSS? desmoglein 1
What host factors contribute to the development of SSSS? -decreased renal clearance of the toxin -lack of toxin-neutralizing antibodies
Where is the epidermal split in SSSS? within or below the stratum granulosum
What is the prodrome of SSSS? malaise, fever, irritability, tenderness of the skin, rhinorrhea, conjunctivitis -erythema of the head with variable facial edema that occurs 48 hours before the onset
What are the differences between staph and strep toxic shock syndromes? patients with strep typically have a localized soft tissue infection with lacerations, bites, etc -strep often has positive blood cultures (staph does not) -mortality is much higher for strep (50-60%)
What are the clinical features of toxic shock syndrome? -fever -rash (diffuse macular erythema) -desquamation -hypotension -involvement of: GI, CNS, renal, hepatic, mucous membranes
What antibiotic actually suppresses protein and toxin production from staph? clindamycin
What bacteria is the cause of scarlet fever? group A beta hemolytic strep, specifically strep pyrogenic exotoxins A,B,C
What is the typical patient population for scarlet fever? children younger than 10 (after 10 most of the population has developed anti-strep pyrogenic toxin antibodies)
What type of illness does scarlet fever usually follow? tonsillitis or pharyngitis
What are the clinical features of scarlet fever? -sore throat, headache, malaise, chills, anorexia, nausea, and high fever, abdominal pain, vomiting -cutaneous eruption begins 12-48 hours later as blanchable erythema on the neck, chest, and axillae with small papules that feel like sandpaper
What are the cutaneous features of scarlet fever? -"sunburn with goose pimples" that develops 12-48 hours after the onset of the illness -Pastia's lines (linear petechial streaks) in the axillae, antecubital, and inguinal areas -flushed cheeks -circumoral pallor -strawberry tongue -desquamation
What are Pastia's lines? linear petechial streaks that occur in the axillae, antecubital fossae, and inguinal area with scarlet fever
Where does the desquamation in scarlet fever classically occur? palms and soles
What is the treatment of scarlet fever? amoxicillin
What types of strep cause strep toxic shock syndrome? M types 1 and 3 of group A strep
What molecules do superantigens bind to? MHC class II on APCs and VB region of the T cell receptor
What is the typical source for strep toxic shock syndrome? soft tissue infection with sudden onset of pain in an extremity
What is the treatment of choice for strep toxic shock syndrome? clindamycin
Erysipelas is also known as? St. Anthony's fire
What is erysipelas? superficial variant of cellulitis caused by group A strep
What is the most common cause of erysipelas? group A strep
What is the typical patient population that is affected by erysipelas? -very young -elderly -the debilitated (esp lymphedema or chronic cutaneous ulcers)
What is the classic location for erysipelas? face
What is the clinical appearance of erysipelas? sharply marginated, erythematous plaque that is slightly tender
What is the treatment of choice of erysipelas? penicillin
What patient population often has recurrent erysipelas? patients with lymphedema
What are the clinical features of perianal strep? -sharply demarcated bright red erythema -perianal pruritus -painful defectation -blood-streaked stools -anal leakage
What clinical infection often precedes perianal strep? strep pharyngitis
What organism can cause positive blood cultures in cellulitis? H. influenzae
What is the most common organism involved in pyomyositis? staph aureus
What is the diagnostic method of choice of pyomyositis? MRI
What is the most common cause of botryomycosis? staph aureus
What are the cutaneous features of botryomycosis? cutaneous and subcutaneous nodules, ulcers, and verrucous plaques that discharge purulent yellow granules
What are the histologic features of botryomycosis? chronic inflammatory reaction with fibrosis and foreign body giant cells -granular bodies (grains) that are bacteria, cells, and debris. -have basophilic centers and eosinophilic periphery
What is the Splendore-Hoeppli phenomenon? -intensely eosinophilic material that radiates around organisms -caused by a local antigen-antibody reaction
What is the treatment of botryomycosis? excision or surgical debridement
What are Osler's nodes? TENDER, erythematous papules and noules on the finger pads and thenar/hypothenar eminences -caused by immune complex deposition and small vessel vasculitis
What are Janeway lesions? PAINLESS, small hemorrhagic macules on the palms and soles -caused by septic emboli with microabscesses
What is the most common organism implicated in gas gangrene? Clostridium perfringens (>80%)
How is the exudate in anaerobic cellulitis and gas gangrene described? thin, dark gray-brown, (dirty dishwater)
What toxins are responsible for gas gangrene? alpha toxin and perfringolysin
Corynebacterium are gram positive or negative? gram positive rods
What organism causes erythrasma? Corynebacterium minutissimum
Where are the common locations for erythrasma? groin, axillae, intergluteal fold, inframammary areas (warm, moist environments)
What are the clinical features of erythrasma? pink to red, well-defined patches that are covered with fine scales and have associated wrinkling. with time, the color fades to brown -asymptomatic
How does erythrasma appear under the Wood's lamp? bright coral red
What causes the fluorescent color of erythrasma? porphyrin produced by the bacteria
What culture medium is used to grow Corynebactrium? Tissue Culture Medium 199
What are topical therapies for erythrasma? 20% aluminum chloride, clindamycin, erythromycin, azoles, Whitfield ointment
What is the most common bacterial infection of the foot? Interdigital erythrasma (chronic macerated fissuring)
What organism causes pitted keratolysis? Kytococcus sedentarius
What enzymes are produced by Kytococcus sedentarius to cause pitted keratolysis? serine proteases (K1 and K2) that degrade keratin
What are the clinical features of pitted keratolysis? 1-7mm crater like depressions within the stratum corneum of the weight-bearing regions of the soles -no associated erythema -often unnoticed by the patient
How does fluorescence of pitted keratolysis appear? it doesn't fluoresce
What are treatment options for pitted keratolysis? topical erythromycin, clindamycin, mupirocin, tetracycline, or azoles
What organism causes trichomycosis axillaris? corynebacterium tenuis
What is the clinical appearance of trichomycosis axillaris? yellow, red or black adherent concretions on the axillary or pubic hair -characteristic odor -sweat can turn red and stain clothing
How does trichomycosis axillaris fluoresce with a Wood's lamp? pale yellow
What is the treatment for trichomycosis axillaris? shave the hair and topical erythromycin or clindamycin
How does cutaneous diphtheria present? punched out ulcer with a gray pseudomembrane "eschar"
What is the most common site of cutaneous diphtheria? acral locations
What positive impact does cutaneous diptheria have for unvaccinated children? -can be a form of immunization as the toxin is very slowly absorbed from skin lesions and induces high levels of antibodies
What 3 ways is anthrax transmitted? 1) inhalation 2) ingestion 3) cutaneous inoculation
How is anthrax typically acquired? occupational exposure with infected animal carcasses (woolsorter's disease)
Is anthrax gram positive or negative? gram positive sporulating rod
What is the function of "edema toxin" impairs neutrophil function and affects water homeostasis, leading to edema
What is the function of "lethal toxin"? causes release of TNF-alpha and IL-1B
What 3 toxin components does anthrax require for virulence? protective antigen, lethal factor, and edema factor (combine to form lethal toxin and edema toxin)
Is cutaneous anthrax painful or painless? PAINLESS
What are the clinical features of cutaneous anthrax? -pupuric macule or papule that looks like an insect bite and then vesiculates and forms non-pitting edema -the vesicle ulcerates and becomes hemorrhagic and depressed with a painless black eschar -the eschar dries over 1-2 weeks - no scar
How do anthrax spores appear in culture? "jointed bamboo rod" cells with "curled hair" appearing colonies
Do systemic symptoms commonly occur with cutaneous anthrax? NO
What is the antibiotic of choice for cutaneous anthrax? ciprofloxacin 500mg bid
How is cutaneous anthrax treated? ciprofloxacin- the antibiotic does not alter the evolution of the skin lesions but prevents systemic infection
What bacterial infection should be suspected in a neutropenic patient with a single necrotic bulla? bacillus cereus
What is the causative organism of erysipeloid? Erysipelothrix rhusiopathiae
What occupation is most likely to get erysipeloid? fishermen or people who prepare meat, poultry or fish
What is the classic clinical presentation of erysipeloid? localized erythema/cellulitis that can be pruritic or painful and spares the terminal phalanges
What is the drug of choice for treatment of erysipeloid? Penicillin
What body parts are involved/ not involved in erysipeloid? commonly on the hands with involvement of the finger/web spaces and sparing of the distal phalanx
What types of infections does listeria cause? - GI illness (in elderly, pregnant women, and immunocompromised) -meningitis in immunocompromised -neonatal meningitis or septicemia -primary cutaneous disease (usually in vets)
What is the antibiotic of choice for listeria? Ampicillin
What are risk factors for meningococcemia infections? asplenia and terminal complement deficiency (C5-9)
What is the source of N meningitidis virulence? polysaccharide capsule
Infection with what organism classically causes purpura with irregular outline and central gunmetal gray color? Neisseria
What percent of patients with acute meningococcemia develop a petechial eruption? 30-50%
What is the histologic appearance of skin biopsies in patient's with disseminated meningococcemia? LCV and thrombosis with organisms within the vessels
What are the cutaneous features of disseminated meningococcemia? -petechial eruption -retiform purpura and ischemic necrosis -purpura with a gunmetal gray appearance
What are Rocha-Lima inclusions? masses of intracytoplasmic Bartonella organisms
What 3 Bartonella species cause human infection?` 1) B. henselae 2) B. quintana 3) B. bacilliformis
What two organisms can cause bacillary angiomatosis? B. henselae and B. quintana
Bartonellosis is also known as ? Carrion's disease
What is the vector of bartonellosis? Phlebotomine sandfly
Where does bartonellosis occur? Peru, Ecuador, southwestern Colombia
What are the two phases of Bartonellosis? 1) Oroya fever 2) verruga peruana
What are the clinical manifestations of Oroya fever? sudden onset of dyspnea, weakness, pallor, tachycardia, fever, thirst, anorexia, arthralgias, headache
What are the lab abnormalities seen in Oroya fever? drop in RBC count with massive hemolysis and variable immunodeficiency
What secondary infection are patients with Oroya fever particularly susceptible to? Salmonella enterica
What is verruga peruana? cutaneous nodules that develop on the head and extremities of patients who have recovered from Oroya fever
What is the clinical appearance of verruga peruana? bright red papulesa nd nodules that appear within erythematous patches -found on the head and extremities -heals without scarring
What is the histologic appearance of a verruga peruana? may look like a pyogenic granuloma or Kaposi sarcoma
What organism is the causative agent of Cat Scratch Disease? Bartonella henselae
What are the clinical manifestations of Cat Scratch Disease? -red papule or crusted pustule develops at the site of inoculation -single, large, tender, lymph node with erythema and swelling usually in the axilla
What is the treatment of Cat Scratch Disease? typically no treatment required; complicated cases may require azithromycin or doxycycline
What are the systemic symptoms associated with Cat Scratch Disease? -usually no systemic symptoms -may occasionally have fever, malaise, fatigue
What patient population is typically affected by bacillary angiomatosis? HIV patients
What are the clinical features of bacillary angiomatosis? superficial angiomatous papules and nodules that can look like a pyogenic granuloma
What is bacillary peliosis hepatis? bacillary angiomatosis of the liver caused by B henselae (not quintana)
What is bacillary peliosis splenis? bacillary angiomatosis of the spleen
What are the histologic features of bacillary angiomatosis? lobular proliferations of capillaries and venules with plump, endothelial cells -lots of neutrophils and leukocytoclasia -interstitial clumps of bacteria
What is the antibiotic of choice to treat bacillary angiomatosis? erythromycin
What organism is the causative agent of trench fever? B. quintana
What is the vector of trench fever? human body louse (Pediculosis humanus)
How is Brucellosis transmitted? consumption of unpasteurized milk products or direct contact with animal parts
What are the cutaneous manifestations of Brucellosis? (occur in <10% of patients) disseminated eruption of violaceous papulonodules or morbilliform eruptions, E nodosum
What are the typical clinical manifestations of Brucellosis? nonspecific signs and symptoms of fever, chills, malaise, headache, arthralgias, etc
What is the first-line treatment of Brucellosis? doxycycline
What is the causative organism of Glanders? Burkholderia mallei
What animals does Glanders primarily affect? donkeys, mules, and horses
What are the 4 clinical forms of Glanders? 1) septicemia 2) localized 3) pulmonary 4) chronic
What are the clinical features of localized Glanders? nodule, pustule or vesicle surrounded by hemorrhagic edema at the inoculation site that sloughs and forms a gray-brown base
What are the cutaneous features of chronic Glanders infection? painful subcutaneous and intramuscular abscesses
What is the causative organism of Melioides? Burkholderia pseudomallei
What types of infections can Melioidosis cause? -localized cutaneous -pulmonary disease -acute septicemia -abscesses and granulomas -cellulitis, echthyma, purpura, pustulese
What is the most common organism involved in malakoplakia? E. coli
What is the most common location on the skin for malakoplakia? perianal area
What is the most common location overall for malakoplakia? GU tract
What are Michaelis-Gutmann bodies intracytoplasmic laminated concretions that are accumulations of calcified, iron-containing phagolysosomes in Malakoplakia
What are von Hansemann cells? Large macrophages that contain Michaelis-Gutmann bodies in Malakoplakia
What is malakoplakia? chronic granulomatous inflammation with macrophages that are unable to appropriately phagocytose and kill bacteria in immunocompromised hosts
What is the treatment of malakoplakia? surgical excision or long-term antibiotics
What is the causative organism involved in Tularemia? Francisella tularensis
What are the reservoirs for F. tularensis? rabbits, deer flies, and ticks
What is the most common form of Tularemia? ulceroglandular
What are the clinical features of ulceroglandular tularemia? lymphadenopathy that may suppurate and an erythematous, indurated, punched-out ulcer that may last for several weeks
What is the antibiotic of choice for Tularemia? streptomycin
Infection with what organism can cause facial cellulitis with a violaceous hue in young children following an upper respiratory tract infection? Haemophilus influenze
What is the causative organism of Rhinoscleroma? Klebsiella rhinoscleromatis
What are Mikulicz cell? large, vacuolated non-lipidized histiocytes with intracellular bacteria seen in Rhinoscerloma
What two types of cells are commonly seen in Rhinoscleroma? Mikulicz cells (large histiocytes with intracellular bacteria) and Russell bodies (plasma cells with lots of Igs)
What are the 3 stages of Rhinoscleroma? 1) rhinitic 2) granulomatous/infiltrative 3) sclerotic
What are the features of the rhinitic phase of Rhinoscleroma? -rhinitis with purulent rhinorrhea and nasal obstruction
What are the clinical features of the granulomatous phase of rhinoscleroma? granulomatous nodules the form in the nose, pharynx, and larynx -epistaxis -destruction of the nasal cartilage
What are the clinical features of the sclerotic phase of Rhinoscleroma? nodules replaced by fibrous tissue and resultant scarring and stenosis of the airway
What is the causative organism of typhoid fever? Salmonella typhi
What are the cutaneous manifestations of typhoid fever? "rose spots"- pink, blanching, slightly elevated papules on the anterior trunk in groups of 5-15 lesions and come in crops during the 2nd to 4th weeks of the illness
What is the drug of choice to treat typhoid fever? quinolones
What is the causative organism of Rat-Bite Fever? Streptobacillus moniliformis
What is the classic triad of Rat Bite Fever? 1) fever 2) migratory polyarthritis 3) rash
What are the cutaneous manifestations of Rat Bite Fever? acrally distributed morbilliform eruption on the palms and soles with papules, petecthia, vesicles, pustules 2-4 days following the onset of the fever
What is the drug of choice to treat Rat Bite Fever? Penicillin
What is the causative organism involved in the plague? Yersinia pestis
What are the 3 types of plague? 1)bubonic 2)septicemic 3)pulmonic
What is the causative organism of typhoid fever? Salmonella typhi
What are the cutaneous manifestations of typhoid fever? "rose spots"- pink, blanching, slightly elevated papules on the anterior trunk in groups of 5-15 lesions and come in crops during the 2nd to 4th weeks of the illness
What is the drug of choice to treat typhoid fever? quinolones
What is the causative organism of Rat-Bite Fever? Streptobacillus moniliformis
What is the classic triad of Rat Bite Fever? 1) fever 2) migratory polyarthritis 3) rash
What are the cutaneous manifestations of Rat Bite Fever? acrally distributed morbilliform eruption on the palms and soles with papules, petecthia, vesicles, pustules 2-4 days following the onset of the fever
What is the drug of choice to treat Rat Bite Fever? Penicillin
What is the causative organism involved in the plague? Yersinia pestis
What are the 3 types of plague? 1)bubonic 2)septicemic 3)pulmonic
What are the clinical features of the bubonic plague? the site of inoculation may develop a pustule or ulcer followed by painful LAD and suppuration
What is the treatment of choice for plague? streptomycin
What organism should be suspected in a fisherman with a painful erythematous, edematous cellulitis that rapidly progresses to hemorrhagic bullae? Vibrio vulnificus
What are the risk factors for Vibrio vulnifus infections? chronic liver disease, diabetes, or exposure to raw seafood or seawater
What are the clinical features of Vibrio septicemia? -fever, chills, nausea, vomiting, diarrhea, abdominal cramps, hypotension -erythematous to pupuric macules and vesicles with hemorrhagic bullae and necrotic ulcers
What is the first-line treatment of Vibrio vulnificus? doxycycline + Rocephin
What is the vector of Lyme disease? Ixodes tick
What organisms are the most common cause of Lyme disease in Europe? Borrelia garinii and Borrelia afzelii
How long does a tick have to be attached to transmit Lyme disease? usually over 24 hours
What is the classic cutaneous manifestation of Lyme disease? erythema migrans
What organisms cause Borrelia lymphocytomas? B. garinii and B afzelii (not found in the US)
Where are the classic locations for Borellia lymphocytomas? earlobes of children and nipple/areola of adults
What percent of patients with Lyme disease in Europe develop acrodermatitis chronica atrophicans? 10%
What is thought to be the cause of acrodermatitis chronica atrophicans? long-term persistence of the spirochete in the skin
What are the clinical features of the early stage of acrodermatitis chronica atrophicans? erythematous to violaceous plaques and nodules develop on acral extremities -follows a waxing and waning course over years
What are the clinical features of the late stage of acrodermatitis chronica atrophicans? -glistening "cigarette paper" appearance with prominent blood vessels -hypo or hyper pigmentation, pain, pruritus, hyperesthesia, paresthesia
What are the treponemal tests that are specific for treponemal infection? TPHA, FTA-ABS, MHA-TP
What are the non-treponemal tests? RPR, VDRL
What antibiotic should be used to treat patients with treponemal infection who are allergic to penicillin? doxycycline
What is the causative organism of Yaws? T pallidum, subspecies pertenue
What is the primary stage of yaws? "mother yaw"- erythematous, infiltrated painless papule that occurs at the site of inoculation and heals spontaneously -the lesion is rich in treponemes
What is the secondary stage of yaws? "daughter yaws"- smaller more widespread papules that usually occur at body orifices, such as the nose and mouth
Where is yaws endemic? tropical climates- Africa, Asia, South and Central America
What is the final stage of yaws? abscesses form that become necrotic and ulcerate, forming sinus tracts that heal with scarring and may form crippling deformities -also may have periostitis, dactylitis, osteitis (saber shins)
What is the causative organism of pinta? Treponema carateum
Where is pinta endemic? Central and South America
What is the primary lesion in pinta? tiny macules or papules surrounded by an erythematous halo that develop into poorly defined erythematous plaques over months
What are the secondary lesions in pinta? "pintids"- small scaly papules that coalesce to form psoriasiform plaques that are initially red but then become slate-blue, brown or black (highly infectious)
What are the tertiary lesions in pinta? symmetric de-pigmented vitiligo-like lesions (not infectious)
What stages of pinta are considered infectious? primary and secondary (tertiary not considered infectious)
Endemic syphilis is also known as? Bejel
What is the causative organism involved in endemic syphilis? T. pallidum, subspecies endemicum
Where is endemic syphilis found? North Africa and Southeast Asia (warm climates)
What is the primary lesion of endemic syphilis? small inconspicuous papule or ulcer in the oropharynx or nipple of breastfeeding women (usually goes unnoticed)
What is the secondary lesion of endemic syphilis? -patches on mucous membranes -split papules -angular stomatitis -condyloma lata -osteoperiostitis which causes nocturnal bone pain
What are the cutaneous manifestations of the tertiary stage of endemic syphilis? gumma formation with gross mutilation of the skin, mucous membranes, muscle and cartilage
How is leptospirosis transmitted? contact of non-intact skin or mucous membranes with urine of infected animals (rodents)
What are the two forms of leptospirosis? 1) anticteric (>90%) 2) icteric (<10%)- more severe
What are the cutaneous manifestations of leptospirosis? variable- erythematous macules, papules, patches, or plaques and petechiae or purpura from vascular involvement
What is the most common presentation of actinomycosis? cervicofacial (lumpy jaw) caused by poor dental hygiene or a recent dental infection
Where is actinomyces normal flora? the human mouth, GI tract, and female genital tract
What are the 3 forms of actinomycosis? 1) cervicofacial (most common) 2) pulmonary (caused by aspiration) 3) GI
What is the drug of choice for treatment of actinomycosis? penicillin
Created by: criddel