Block 15 Bacterial Viral Fungal Skin Lesions
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A 22-year-old presents with a toenail that concerns her. What would you expect to see in the microscope? Note some are stained
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About This Quiz
CTL: Cutaneous/ SubQ Mycoses
CTL: Inflammatory skin diseases; viral exanthems and enanthems; skin path
CTL: Patient with rash; skin flora, bacterial infections; zoonotic infections
Quiz Preview
- 2.
A 57-year-old oncologist who is also an avid gardener presents with a swollen series of three nodules on his left hand. He says that he believes they started from some trauma acquired from poking himself while picking limes off of his tree. (Lime trees have spiny little branches.) He remembers from medical school that there was some fungus that was common on plant material that could start these infections and that it had a shared characteristic with some of the systemic fungal pathogens. What is the most likely causative agent?
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Histoplasma capsulatum
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Candida albicans
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Actinomyces israeli
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Malassezia furfur
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Sporothrix schenckii
Correct Answer
A. Sporothrix schenckiiExplanation
The most likely causative agent for the swollen nodules on the oncologist's hand is Sporothrix schenckii. This is because the oncologist recalls that the infection may have started from trauma acquired while picking limes, which suggests a fungal infection. Sporothrix schenckii is a fungus commonly found on plant material and can cause infections when it enters the skin through wounds or punctures. Additionally, the mention of shared characteristics with systemic fungal pathogens further supports the likelihood of Sporothrix schenckii as the causative agent.Rate this question:
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- 3.
Your patient is a sportsman who plays racket ball at a local club, softball, and hockey in the winter. The patient presents with a pruritic, erythematous, moist, rash on his groin. The infected area is the skin on the upper thigh and especially folds on the lower abdomen; both the scrotum and penis are spared. What is the most likely causative agent of this patient’s condition?
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Sporothrix schenkii
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Trichophyton schoenleinii
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Trichophyton rubrum
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Candida albicans
Correct Answer
A. Trichophyton rubrumExplanation
The most likely causative agent of this patient's condition is Trichophyton rubrum. This is because the patient presents with a pruritic, erythematous, moist rash on his groin, specifically on the skin of the upper thigh and folds on the lower abdomen. Trichophyton rubrum is a common dermatophyte fungus that causes infections in these areas, known as tinea cruris or jock itch. The fact that the scrotum and penis are spared also supports this diagnosis, as these areas are typically not affected by this fungal infection.Rate this question:
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- 4.
A six year-old boy presents with complaints of itchy head. Two weeks ago, he was treated by a nurse clinician for a sore throat. On closer examination, you find small scaling patches of hair on three different areas. These are not significantly inflamed, nor is there exudate present but there appear to be fewer hairs in these patches and the hair color appears to be somewhat hypopigmented. The hairs fluoresce under the Wood's lamp. There is nothing obvious attached to the hairs. What is the most likely diagnosis?
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Nits and lice acquired from shared baseball caps, brushes and combs
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Tinea capitis from shared caps, brushes and combs
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Candida spp. from antibiotic administration for pharyngitis
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Ringworm from a neighbor's dog
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Measles from respiratory route from a second unvaccinated child
Correct Answer
A. Tinea capitis from shared caps, brushes and combsExplanation
The most likely diagnosis in this case is tinea capitis, which is a fungal infection of the scalp. The symptoms of itchy head, small scaling patches of hair, and hypopigmented hair are consistent with tinea capitis. The fact that the hairs fluoresce under the Wood's lamp also supports this diagnosis. Additionally, the history of sharing caps, brushes, and combs suggests that the infection was acquired through these means.Rate this question:
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- 5.
A 44-year-old woman presented to a dermatologist with a 3-month history of painless, splotchy hypopigmentation on her back and arms. The skin fluoresced under a Wood’s lamp. The diagnosis was tinea versicolor. What caused it?
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Tinea corporis
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Actinomyces
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Erysipelothrix
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Malassezia furfur
Correct Answer
A. Malassezia furfurExplanation
The correct answer is Malassezia furfur. Tinea versicolor is a fungal infection caused by Malassezia furfur. This fungus is a normal inhabitant of the skin, but under certain conditions, such as hot and humid weather or a weakened immune system, it can overgrow and cause skin discoloration. The splotchy hypopigmentation seen in this patient is characteristic of tinea versicolor, and the fluorescence under a Wood's lamp is a diagnostic feature of this condition. Tinea corporis, Actinomyces, and Erysipelothrix are not associated with the presentation described.Rate this question:
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- 6.
A 40-year-old Caucasian female presents with a complaint of rash that has developed over the last several weeks and seems to be progressing. On examination, she is noted to have several lesions over the extensor surfaces of both upper and lower extremities as well as similar lesions on her scalp. The macroscopic and microscopic appearance of the lesion is shown for you evaluation below. Which of the following is the most likely diagnosis?
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Lichen planus
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Psoriasis
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Eczema
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Discoid lupus erythematosus
Correct Answer
A. PsoriasisExplanation
The patient's presentation of rash that has been progressing over several weeks, with lesions on the extensor surfaces of both upper and lower extremities as well as the scalp, is consistent with psoriasis. Psoriasis is a chronic autoimmune condition characterized by red, scaly patches on the skin. The macroscopic and microscopic appearance of the lesion would further support the diagnosis of psoriasis. Lichen planus, eczema, and discoid lupus erythematosus can present with similar skin manifestations, but the clinical presentation described in the question is most indicative of psoriasis.Rate this question:
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- 7.
A 33-year-old Caucasian male visits his dermatologist complaining of painful, blistering skin lesions over his back, chest, and arms that break down and leave denuded skin areas. On questioning, he reports that over the past few years he has had large recurrent aphtous ulcers in the mouth. He was not taking any drugs before his symptoms developed. Physical examination reveals large aphtous ulcers over oral mucosa and large bullous skin lesions. Vertical pressure over bullae leads to lateral expansion; skin over bullae peels like that of “hot tomato”. The gross and microscopic appearance of the lesion is presented in the images below.
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Bullous pemphigoid
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Pemphigus vulgaris
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Dermatitis herpetiformis
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Erythema multiforme
Correct Answer
A. Pemphigus vulgarisExplanation
The patient's presentation of painful, blistering skin lesions that break down and leave denuded skin areas, along with the presence of large aphtous ulcers in the mouth, is consistent with pemphigus vulgaris. Pemphigus vulgaris is an autoimmune blistering disorder that affects the skin and mucous membranes. The characteristic finding of lateral expansion and peeling of the skin over bullae with vertical pressure supports this diagnosis. Bullous pemphigoid, dermatitis herpetiformis, and erythema multiforme do not typically present with oral ulcers and do not exhibit the same peeling characteristic.Rate this question:
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- 8.
A 13-year-old girl is seen in the emergency department with a rash covering her entire body consisting of itchy blisters in various stages. The rash had appeared first on the trunk and face after the girl had been “sick with the flu”. What is the structure of the viral genome of the virus most likely causing this disease?
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Negative sense, single-stranded RNA
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Positive sense, single-stranded RNA
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Either positive- or negative-sense, single-stranded DNA
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Double-stranded RNA
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Double-stranded DNA
Correct Answer
A. Double-stranded DNAExplanation
The presence of a rash and flu-like symptoms suggests a viral infection. Viruses with a double-stranded DNA genome are most commonly associated with skin manifestations, such as the rash described in the question. Other types of viral genomes, such as single-stranded RNA or DNA, are less likely to cause this specific presentation. Therefore, the most likely structure of the viral genome causing this disease is double-stranded DNA.Rate this question:
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- 9.
Measles is making something of a resurgence in some Western countries due to lack of vaccination. It is often said that the typical symptoms of measles, in addition to Koplik’s spots, are the 3 C’s (plus P). What does this mean?
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Cough, coryza, conjunctivitis (+ photophobia)
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Colic, cough, cachexia (+ pimples)
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Colic, caecitis, cough (+ purulence)
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Cough, coryza, child (+ polymorphonuclear cells)
Correct Answer
A. Cough, coryza, conjunctivitis (+ photophobia)Explanation
The typical symptoms of measles, in addition to Koplik's spots, are cough, coryza, and conjunctivitis, along with photophobia. This means that individuals with measles may experience a cough, a runny nose (coryza), and inflammation of the conjunctiva (the clear tissue that covers the white part of the eye and inner surface of the eyelids), which can cause redness, itching, and discharge. Photophobia refers to sensitivity to light, which can be a symptom of conjunctivitis.Rate this question:
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- 10.
A 3-year-old boy in Brazil, who had not received MMR vaccine, developed fever followed by a diffuse maculo-papular erythematous rash. His pediatrician suspected rubeola caused by measles virus or fifth disease caused by parvovirus B19. These two viruses differ in which respects?
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One has a single-stranded genome, the other a double-stranded genome
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One has DNA, the other has RNA; one is enveloped, the other is naked
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One has DNA, the other has RNA; both are enveloped
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Both have RNA; one is enveloped, the other is naked
Correct Answer
A. One has DNA, the other has RNA; one is enveloped, the other is nakedExplanation
The correct answer is that one virus has DNA, while the other has RNA. Additionally, one virus is enveloped, while the other is naked. This means that the measles virus, which causes rubeola, has RNA and is enveloped, while parvovirus B19, which causes fifth disease, has DNA and is naked.Rate this question:
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- 11.
A 6-year old child is seen with a prominent bright red rash that appeared 2 days earlier on the cheeks. The child has a sore throat and a low-grade fever. Which of the following statements describes most accurate the major site of viral replication of the infectious agent?
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Lymphocytes and monocytes
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Erythroid progenitor cells
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Epithelial cells and endothelial cells
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Neurons
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Osteoblasts and chondroblasts
Correct Answer
A. Erythroid progenitor cellsExplanation
The given clinical presentation of a bright red rash on the cheeks, sore throat, and low-grade fever is consistent with a viral infection called Fifth disease or erythema infectiosum. The major site of viral replication in this infection is the erythroid progenitor cells, which are found in the bone marrow and are responsible for the production of red blood cells. The virus infects and replicates within these cells, leading to the characteristic rash and other symptoms.Rate this question:
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- 12.
An 11-year-old boy bas a benign growth on his foot that is characterized by hyperplasia of the prickle cells. What of the following the most likely cause of the growth?
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Fungus that exhibits septate hyphae and is not thermally dimorphic
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Virus whose replication is dependent on the epithelial cell differentiation stage
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Fungus that metabolizes keratin
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Large, enveloped, linear double-stranded DNA virus
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Virus that replicates in most tissue culture cells
Correct Answer
A. Virus whose replication is dependent on the epithelial cell differentiation stageExplanation
The most likely cause of the growth is a virus whose replication is dependent on the epithelial cell differentiation stage. This is because the growth is characterized by hyperplasia of the prickle cells, which are found in the epithelial layer of the skin. The fact that the virus's replication is dependent on the differentiation stage suggests that it specifically targets and affects the growth and development of these cells, leading to the benign growth on the boy's foot.Rate this question:
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- 13.
The skin lesion shown would be best described as a/an:
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Plaque
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Macule
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Papule
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Patch
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Pustule
Correct Answer
A. PapuleExplanation
The skin lesion shown in the question is best described as a papule. A papule is a small, elevated, solid lesion that measures less than 1 centimeter in diameter. It is usually caused by inflammation or localized cellular infiltration. In the image, the lesion appears as a raised bump on the skin, which fits the description of a papule. Plaque, macule, patch, and pustule are not appropriate descriptions for the lesion in the image.Rate this question:
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- 14.
This 25 -year-old female presents with a long history of an intermittent pruritic rash on her abdomen. Most likely diagnosis would be
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Scabies
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Pityriasis versicolor
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Atopic Dermatitis
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Contact Dermatitis
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Psoriasis
Correct Answer
A. Contact DermatitisExplanation
The most likely diagnosis for this 25-year-old female with a long history of an intermittent pruritic rash on her abdomen would be contact dermatitis. Contact dermatitis is a common skin condition characterized by inflammation of the skin caused by direct contact with an irritant or allergen. It typically presents with symptoms such as itching, redness, and rash, which are consistent with the patient's symptoms. Scabies, pityriasis versicolor, atopic dermatitis, and psoriasis may also cause similar symptoms, but given the history of intermittent rash and the likely exposure to irritants or allergens, contact dermatitis is the most probable diagnosis.Rate this question:
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- 15.
On examination of a patient you observe the rash shown in the image. You would describe this rash as
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Macular
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Petechial
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Papular
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Lichenification
Correct Answer
A. PetechialExplanation
The rash shown in the image appears as small, pinpoint-sized red or purple spots on the skin. This is characteristic of a petechial rash, which is caused by bleeding under the skin. Petechiae are often a result of tiny blood vessels called capillaries bursting, and can be caused by various factors such as trauma, infection, or certain medical conditions.Rate this question:
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- 16.
A 19 year old female college freshman presents to your office for a physical exam. On ROS she admits to intermittent vaginal itching and white discharge. She is not sexually active. She is adopted and does not know any of her family medical history. In addition to a curdly white discharge present on vulvar inspection, you note the following on physical examination: BMI 32.2. You order a wet prep microscopic examination of her vaginal discharge. Of the following, what is the most appropriate next step?
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Order a serum cortisol
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Order a lipid profile
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Order a fasting insulin level
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Order a fasting blood glucose and oral glucose tolerance test
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Order a GC/Chlamydia PCR
Correct Answer
A. Order a fasting blood glucose and oral glucose tolerance testExplanation
Based on the patient's symptoms of vaginal itching and white discharge, along with a high BMI of 32.2, the most appropriate next step would be to order a fasting blood glucose and oral glucose tolerance test. These symptoms could be indicative of a possible yeast infection, which can be more common in individuals with diabetes or prediabetes. Additionally, the high BMI suggests a higher risk for developing diabetes or prediabetes. Therefore, it is important to assess the patient's blood glucose levels to rule out any underlying metabolic abnormalities.Rate this question:
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- 17.
Your patient presents with intense pain around the wound, subsequent to amputation of the left leg following a farming accident. He is febrile and incoherent. The wound is bronze-colored and displays crepitus on palpation. A sample of exudate submitted for anaerobic culture grew the organism seen in the Gram stain image below. What is the most likely causative agent?
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Corynebacterium diphtheria
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Clostridium perfringens
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Staphylococcus aureus
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Clostridium tetani
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Bacillus cereus
Correct Answer
A. Clostridium perfringensExplanation
The patient's symptoms of intense pain, fever, and incoherence, along with the characteristics of the wound (bronze-colored and displaying crepitus on palpation), suggest the presence of gas gangrene. Clostridium perfringens is the most likely causative agent for this condition, as it is commonly associated with gas gangrene.Rate this question:
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- 18.
Your patient is a 52-y-o patient who has just noticed a callous on her foot. The patient is diabetic with poor glycemic control, a BMI of 32, and is a lifelong smoker. Upon examination, you note that the foot is swollen, the skin has been broken, and there is a purulent wound. There is insensitivity to the Semmes-Weinstein 5.07 (10 g) monofilament. Analysis of the major pathogen in the wound of this patient reveals a Gram-positive, catalase-positive, and coagulase-positive coccus which is strongly -hemolytic. What is this pathogen?
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Streptococcus pyogenes
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Staphylococcus aureus
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Staphylococcus epidermidis
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Enterococcus faecalis
Correct Answer
A. Staphylococcus aureusExplanation
The patient in the scenario is a diabetic with poor glycemic control, a high BMI, and is a lifelong smoker. These factors put the patient at a higher risk for developing foot ulcers and infections. Upon examination, the foot is swollen, the skin has been broken, and there is a purulent wound. The presence of a Gram-positive, catalase-positive, and coagulase-positive coccus that is strongly -hemolytic suggests Staphylococcus aureus as the pathogen. Staphylococcus aureus is a common cause of skin and soft tissue infections, especially in individuals with compromised immune systems or chronic illnesses like diabetes.Rate this question:
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- 19.
A 35-year-old man suffered a 3rd degree electrical burn to his left arm. One week later, while being prepared for a skin graft, some burned areas began to exude blue-green pus with a fruity odor. What would you expect to grow?
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A Gram-negative, oxidase-positive rod
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A Gram-positive, catalase-positive coccus in clumps
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An anaerobic spore-forming Gram-positive rod
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A Gram-negative, oxidase-negative rod
Correct Answer
A. A Gram-negative, oxidase-positive rodExplanation
An opportunistic, nosocomial pathogen of immunocompromised individuals, P. aeruginosa typically infects the pulmonary tract, urinary tract, burns, wounds, and also causes other blood infections
It is a Gram-negative, aerobic, rod-shaped bacterium with unipolar motility. An opportunistic human pathogen, P. aeruginosa is also an opportunistic pathogen of plants. P. aeruginosa is the type species of the genus Pseudomonas (Migula)
P. aeruginosa secretes a variety of pigments, including pyocyanin (blue-green), pyoverdine (yellow-green and fluorescent), and pyorubin (red-brown).Rate this question:
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- 20.
A pathogen considered a prime candidate for germ warfare (i.e., bioterrorism) is a very small, encapsulated, Gram-negative coccobacillus that grows slowly on chocolate agar. Infection can be via a number of routes, including inhalation, direct contact, and ingestion. In the U.S., people who come into contact with infected rabbits are at risk. Which pathogen is this?
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Francisella tularensis
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Bacillus anthracis
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Brucella abortus
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Pasteurella multocida
Correct Answer
A. Francisella tularensisExplanation
FRANCISELLA TULARENSIS is a pathogenic species of Gram-negative bacteria and the causative agent of tularemia or rabbit fever. It is a fastidious, facultative intracellular bacterium which requires cysteine for growth. Due to its ease of spread by aerosol and high virulence, F. tularensis is classified as a Class A Select Agent by the U.S. government, along with other potential agents of bioterrorism such as Yersinia pestis, Smallpox and the Filoviruses.
Infection with F. tularensis can occur via several routes. The most common occurs via skin contact, yielding an ulceroglandular form of the disease. Inhalation of bacteria - particularly biovar tularensis, leads to the potentially lethal pneumonic tularemia. While the pulmonary and ulceroglandular forms of tularemia are more common, other routes of inoculation have been described and include oropharyngeal infection due to consumption of contaminated food and conjunctival infection due to inoculation at the eye.
F. tularensis is capable of surviving outside of a mammalian host for weeks at a time and has been found in water, grassland, and haystacks. Aerosols containing the bacteria may be generated by disturbing carcasses due to brushcutting or lawn mowing; as a result, tularemia has been referred to as lawnmower disease. Recent epidemiological studies have shown a positive correlation between occupations involving the above activities and infection with F. tularensis.
Life cycle
F. tularensis is a facultative intracellular bacterium that is capable of infecting most cell types but primarily infects macrophages in the host organism. F. tularensis entry into the macrophage occurs via phagocytosis and the bacterium is sequestered from the interior of the infected cell by a phagosome. F. tularensis then breaks out of this phagosome into the cytosol and rapidly proliferates. Eventually the infected cell undergoes apoptosis, and the progeny bacteria are released to initiate new rounds of infection.Rate this question:
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.JPG "A 40-year-old Caucasian female presents with a complaint of rash that has developed over the last several weeks and seems to be progressing. On examination, she is noted to have several lesions over the extensor surfaces of both upper and lower extremities as well as similar lesions on her scalp. The macroscopic and microscopic appearance of the lesion is shown for you evaluation below. Which of the following is the most likely diagnosis?")
.JPG "A 33-year-old Caucasian male visits his dermatologist complaining of painful, blistering skin lesions over his back, chest, and arms that break down and leave denuded skin areas. On questioning, he reports that over the past few years he has had large recurrent aphtous ulcers in the mouth. He was not taking any drugs before his symptoms developed.
Physical examination reveals large aphtous ulcers over oral mucosa and large bullous skin lesions. Vertical pressure over bullae leads to lateral expansion; skin over bullae peels like that of “hot tomato”. The gross and microscopic appearance of the lesion is presented in the images below.")
.JPG "The skin lesion shown would be best described as a/an:")
.JPG "This 25 -year-old female presents with a long history of an intermittent pruritic rash on her abdomen. Most likely diagnosis would be")
.JPG "On examination of a patient you observe the rash shown in the image. You would describe this rash as")
.JPG "A 19 year old female college freshman presents to your office for a physical exam. On ROS she admits to intermittent vaginal itching and white discharge. She is not sexually active. She is adopted and does not know any of her family medical history. In addition to a curdly white discharge present on vulvar inspection, you note the following on physical examination: BMI 32.2.
You order a wet prep microscopic examination of her vaginal discharge. Of the following, what is the most appropriate next step?")
.JPG "Your patient presents with intense pain around the wound, subsequent to amputation of the left leg following a farming accident. He is febrile and incoherent. The wound is bronze-colored and displays crepitus on palpation. A sample of exudate submitted for anaerobic culture grew the organism seen in the Gram stain image below.
What is the most likely causative agent?")
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Mar 21, 2023Quiz Edited by
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Nov 01, 2012Quiz Created by
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