156 - Miscellaneous Bacterial Infections with Cutaneous Manifestations Flashcards
Bioweapon potential A
Anthrax
Tularemia
Plague
Bioweapon potential B
Brucellosis
Glanders (Burkholderia mallei)
Melioidiosis (Burkholderia pseudomallei)
BBB
Gram-positive bacteria
Bacillus anthrasis Listeria monocytogenes Erysipelothrix rhusiopathiae Streptococcus iniae Corynebacterium diphtheriae
Gram-negative bacteria
Francisella tularensis Yersinia pestis Brucella Burkholderia mallei Pasteurella multocia Streptobacillus moniliformis Spirillum minus Mycoplasma Vibrio vulfinicus Aeromonas hydrophila Burkholderia pseudomallei Chromobacterium violaceum
Worldwide, especially developing agrarian areas
Painless edematous plaque with central black ulcer or eschar; “malignant pustule”; “malignant edema”
Goats, sheep, cattle, or products made from them
Anthrax
Etiologic agent: Anthrax
Bacillus anthrasis
Anthrax route of inoculation
Cutaneous
Inhalational
GI
Injectional
_____ anthrax has a distinct clinical course because it presents without an eschar; more virulent with a much higher mortality rate
Injectional
Injectional anthrax resulted from exposure to
Contaminated heroin
Major virulence factors of Bacillus anthracis
Poly-gamma-D-glutamic acid capsule
Tripartite anthrax toxin
The tripartite anthrax toxin contains 3 proteins
Protective antigen
Lethal factor
Edema factor
Best target for anthrax vaccines or immunotherapy
Protective antigen
Y/N: Lesional progression in anthrax is caused by the bacteria and is responsive to antibiotic therapy
No - caused by toxins and is unaffected by antibiotic therapy
Naturally occurring anthrax is treated with
Penicillin or doxycycline
Recommended initial treatment for confirmed or suspected bioterrorism-associated anthrax
Fluoroquinolone
Humanized monoclonal antibody that has specificity for the bacterial protective antigen, to be used in cases of inhalational anthrax
Raxibacumab
Infectious propagule in anthrax
Spore
Y/N: Anthrax is not transmitted from person-to-person
Yes
Y/N: Untreated cutaneous anthrax, particularly if nonedematous, is a largely self-resolving disease
Yes
Y/N: Patients with injectional, inhalational, or GI anthrax should be placed in intensive care units
Yes
Temperate and gold regions, North America, Europe
Ulceroglandular: painful papule that ulcerates and forms eschar
Tick bites, lagomorphs (rabbits and hares), rodents
Tularemia
Etiologic agent: Tularemia
Francisella tularensis
6 major clinical presentations of tularemia
Glandular Ulceroglandular Oculoglandular Oropharyngeal Typhoidal Pneumonic
Most common form of tularemia in the US
Ulceroglandular
Most common tick vectors of tularemia
Dermacentor variabilis Amblyomma americanum Ixodes sp (in Europe)
Y/N: Tularemia has human-to-human transmission
No human-to-human transmission
Treatment for tularemia
Aminoglycoside antibiotic, such as gentamicin (or streptomycin, if available) or
Fluoroquinolone
Alternative:
Tetracycline antibiotic, such as doxycycline
Antibiotic prophylaxis for tularemia
Ciprofloxacin
Worldwide, especially southwestern US and India
Buboes (tender regional lymphadenopathy) followed by purpura and gangrene (“black death”)
Flea bites, spread from infected rodents
Plague
Etiologic agent: Plague
Yersinia pestis
3 clinical forms of plague
Bubonic
Bubonic-septicemic
Pneumonic
Original drug of choice for plague
Streptomycin
Preferred treatment for plague since streptomycin is not widely available
Gentamicin
Other treatments for plague
Doxycycline
Cotrimoxazole
Antibiotic prophylaxis for plague
Doxycycline
Cotrimoxazole
Worldwide, especially developing agrarian areas
Variable; skin manifestations present in <5% of patients; characteristic undulant fever
Cattle, sheep, goats, or untreated milk
Brucellosis
Etiologic agent: Brucellosis
Brucella melitensis
Brucella abortus
Most common source of human brucellosis
Contaminated unpasteurized milk or cheese
Brucellosis is more common in (children/adults)
Children
Most frequently involved organs
Joints
Reproductive organs
Liver
CNS
For brucellosis cultures, _____ specimens have the highest yield
Bone marrow
Treatment for brucellosis
Prolonged multidrug therapy with doxycycline combined with either streptomycin or gentamicin
WHO: Doxycycline and rifampicin
Rare and focal in Asia, Middle East
Nodule with cellulitis that ulcerates; ulcer is painful and has irregular edges with a gray-yellow base; later, deep abscesses and sinuses
Donkeys, mules, horses
Glanders
Etiologic agent: Glanders
Burkholderia mallei (formerly Pseudomonas mallei)
Glanders is usually fatal in _____, but may cause a chronic suppurative condition, called farcy, in _____
Donkeys and mules
Horses
Presentation of glanders
Acute localized infection
Chronic cutaneous infection
Acute pulmonary disease
Septicemia
Characteristic eruption of bacteremic spread of glanders
Crops of papules, bullae, and pustules
Mucopurulent, bloody nasal discharge is common
Treatment for glanders
Sulfadiazine
Worldwide
Rapid onset of cellulitis at bite site followed by necrosis
Dog or cat bite
Pasteurella infection
Y/N: Pasteurella multocida is a normal flora in oropharynx of many domestic animals
Yes
Because most animal bite wounds show polymicrobial contamination, _____ should be started
Amoxicillin-clavulanic acid
Drug of choice if Pasteurella is cultured
Penicillin
Worldwide, especially Asia
Morbiliform eruption with fever followed by arthritis; palms and soles have a characteristic desquamation
Rats or their excreta
Rat-bite fever (streptobacillary)
Etiologic agent: Rat-bite fever
Streptobacillus moniliformis
Spirillum minus
More common form of rat-bite fever is caused by
Streptobacillus moniliformis
Japanese name of spirillary rat-bite fever
Sodoku
Best way to confirm the diagnosis of streptobacillary rat-bite fever
Blood cultures
In (S. moniliformis/S. minus) infection, the incubation period is shorter (usually <10 days vs >14 days), the bite site usually heals before systemic symptoms begin, the rash is more peripheral, and arthritis is more common (60% vs 20%)
S. moniliformis
Treatment of choice for someone who becomes ill after a rat bite
Amoxicillin-clavulanic acid
Allergic to penicillin: doyxcycline
Once S. moniliformis is identified, _____ is the drug of choice
Penicillin
Although there are no established guidelines, one might consider a prompt prophylactic course of _____ after any rat bite
Penicillin or
Doxycycline
Cool coastal regions worldwide
Extremely painful nodule on finger
Seals or sea lions, and similar marine mammals (order Pinnipedia)
Seal finger
Etiologic agent: Seal finger
Mycoplasma
Has not been fully confirmed
Seal finger does not respond to the _____ antibiotics frequently prescribed presumptively for cellulitis caused by Staphylococcus, Streptococcus, or Erysipelothrix
Beta-lactam
Treatment of choice for seal finger
Tetracyclines
Worldwide
In neonates, generalized petechiae, papules, and pustules
In neonates, infected mother with transfer in utero or shortly after birth
Listeriosis
Listeria monocytogenes is found widely in
Soil, water, vegetation, and the gut flora of humans and other animals
Exposure to Listeria monocytogenes occurs through
Fecal-oral contamination
Human listeriosis is most common in
Pregnant women
Neonates
Patients with AIDS
Foodborne outbreaks
Approximately _____% of humans are fecal carriers of Listeria
5
Highest incidence of human listeriosis is seen among
Infants in the perinatal period
Generally ineffective for listeriosis
Cephalosporins
Treatment for listeriosis
IV amplicillin (or penicillin)
Penicillin-allergic: cotrimoxazole or erythromycin
Worldwide; particularly common along the Gulf of Mexico
Necrotizing fasciitis, hemorrhagic bullae often beginning as a wound infection
Warm saltwater or brackish water or undercooked seafood
Vibrio vulfinicus infection
V. vulfinicus clinical syndromes
Gastroenteritis
Primary sepsis
Primary wound infection
Antibiotics of choice for V. vulfinicus infection
Combination of doxycycline and ceftazidime
Some authors consider a course of prophylactic _____ for an immunocompromised person with a high-risk exposure
Oral doxycycline
Worldwide
Cellulitis evolving to abscess formation; exudate often has a foul or fishy odor; often beginning as wound infection
Fresh or brackish water, contaminated fish
Aeromonas hydrophila
Increasing number of soft-tissue infections caused by Aeromonas hydrophila are associated with the medical use of
Leeches (Hirudo medicinalis)
A. hydrophila produces beta-lactamase and is resistant to
First-generation penicillins
Cephalosporins
Treatment for Aeromonas hydrophila infection
Third-generation cephalosporins
Fluoroquinolones
Aminoglycosides (but not streptomycin)
Wet tropical areas, especially Southeast Asia and Northern Australia Indolent abscesses; suppurative parotitis (in children) Wet soil (classically rice paddies), flooded regions
Melioidosis
Etiologic agent: Melioidosis
Burkholderia pseudomallei (formerly Pseudomonas pseudomallei)
Peak incidence of melioidosis during
Rainy monsoon seasons
Principal clinical presentations of melioidosis
Acute melioidosis with suppurative skin lesions, pneumonia, or septicemia
Chronic melioidosis, the more common form of the disease, with involvement of the lungs, skin, bones, joints, liver, and spleen
Most commonly used test in Southeast Asia for melioidosis because it is simple to perform and cheap
Indirect hemagglutination assay
Treatment for melioidosis
IV antibiotics (usually ceftazidime and carbapenem) followed by several months of high-dose oral therapy with trimethoprim-sulfamethoxazole or amoxicillin-clavulanic acid
Worldwide
Tender violaceous plaque on hand at site of injury
Contaminated fish, shellfish, poultry, meat, and animal products
Erysipeloid
Etiologic agent: Erysipeloid
Erysipelothrix rhusiopathiae
Clinical forms of erysipeloid
Local nonsuppurative cutaneous infection (erysipeloid of Rosenbach)
Diffuse chronic cutaneous form
Subacute bacterial endocarditis, particularly of the aortic valve
Bacteremic form without endocarditis
Y/N: Erysipeloid often involves the web spaces but spares the terminal phalanges and does not progress beyond the wrist
Yes
Treatment of choice for erysipeloid
High-dose penicillin or ampicillin
Cannot take penicillins: third-generation cephalosporins
Worldwide, especially freshwater fish farms
Rapid onset of hand cellulitis following a puncture wound
Contaminated farm-raised fish
Streptococcus iniae
In dolphins, S. iniae causes slow-growing nodular abscesses of the skin and subcutaneous tissues, giving it the vernacular name
“Golf ball disease”
Most cases of erysipeloid have been reported in _____, where the practice of buying live fish for home preparation is common
China and in Asian communities in North America, particularly Toronto
Most people who develop S. iniae infection are
Elderly individuals of Asian descent
Treatment of choice for S. iniae infection
Penicillin
Other treatments for S. iniae infection
Cephalosporins
Macrolides
Quinolones
Vancomycin
S. iniae infection is resitant to
Tetracyclines
Worldwide, especially the tropics
Papules, petechiae, jaundice
Contaminated freshwater, moist soil, or animal urine
Leptospirosis
Etiologic agent: Leptospirosis
Leptospira interrogans
Etiologic agent: Diphtheria
Corynebacterium diphtheriae
Most important reservoirs of Leptospira interrogans
Rodents
Y/N: Infected humans can also serve as transient reservoirs of Leptospira interrogans. Reservoir animals excrete leptospires in their urine
Yes
Leptospiroris is most prevalent among
Children who play or swim in contaminated water
Adults with occupational exposure
Y/N: Most human leptospirosis infections are asymptomatic, self-limited, and detectable only on serologic surveys
Yes
Clinical forms of leptospirosis
Mild anicteric form that resolves without complications
Severe, icteric form (Weil disease)
Phases of leptospirosis
Acute bacteremic phase
Delayed immune or convalescent phase
Caused by L. interrogans serovariant autumnalis
Distinctive rash that appears on the fourth or fifth day of illness, consisting of slightly raised, 1- to 5-cm tender, erythematous papules on the shins
Pretibial fever of Fort Bragg fever
Direct isolation of leptospires is possible from the _____ during the acute phase or from _____ during the convalescent pahse
Blood or CSF
Urine
Effective and can be taken prophylactically for short-term exposure in a hyperendemic area for leptospirosis
Doxycycline 200 mg once weekly
90% of acute febrile illness caused by Corynebacterium diphtheriae affects the
Pharynx and mucous membranes of the upper respiratory tract
Only natural host of Corynebacterium diphtheriae
Humans
Routine childhood immunization for diphtheria is directed againts
Diphtheria’s exotoxin, not the bacteria itself
Types of skin involvement in diphtheria
Primary cutaneous diphtheria
Wound diphtheria
Type of diphtheria that accounts for almost all cases of cutaneous diphtheria reported in the US
Wound diphtheria
Most important other manifestations of diptheria are the toxin’s effects on
Heart
Nerves
Antibiotic of choice for cutaneous diphtheria
High-dose IV penicillin
Unable to take penicillin: erythromycin
Pharyngeal cultures for diphtheria should be repeated _____ after completing treatment
2 weeks
Adults should receive a dose of tetanus and diphtheria toxoid every
10 years
Antibiotic prophylaxis for diphtheria
Oral erythromcyin
Penicillin
Corynebacterium ulcerans is a common organism in
Cattle
_____ disease is most common in Corynebacterium ulcerans infection
Pharyneal
Corynebacterium _____, which causes lymphadenitis in ruminants, occasionally causes a similar necrotizing lymphadenitis in humans
pseudotuberculosis
An organism closely related to corynebacteria, _____ (formerly Corynebacterium equi), causes pulmonary disease in AIDS patients
Can cause skin and soft-tissue infections in healthy individuals, especially those exposed to horse manure or after an injury contaminated with soil
Rhodococcus equi
Worldwide where immunization is not practiced
Pustule or superinfected abrasion, evolving to an ulcer with gray membrane at base
Asymptomatic human carriers
Diphtheria
