Block 9 Infxn Path Anaerobe & Mycology MCQ's

1. A 52-year-old medical missionary has recently returned to the US from a tour in an emerging nation. She presents to her family physician with a complaint of a productive cough and some dyspnea. She says that this has been going on for some time, but she wanted to wait for medical care in the states. She has not history of smoking and rarely drinks alcohol. Physical exam reveals some lung consolidation on auscultation and a low grade fever. A chest x-ray reveals multifocal 1-3 cm nodules, a few being cavitated. Acid fast stains or the sputum reveal acid-fast organisms; however the results of cultures are yet to be determined. Which of the following is the Most Likely cause of the lung lesions?

Fibrinous inflammation

Granulomatous inflammation

Serous inflammation

Suppurative inflammation

Pulmonary abscesses

The most likely cause of the lung lesions in this case is granulomatous inflammation. The patient's history of being a medical missionary in an emerging nation suggests exposure to infectious agents that can cause granulomas, such as tuberculosis. The presence of acid-fast organisms on sputum stains further supports this possibility. Additionally, the chest x-ray findings of multifocal nodules, some of which are cavitated, are consistent with granulomatous inflammation seen in tuberculosis.

Explanation

The most likely cause of the lung lesions in this case is granulomatous inflammation. The patient's history of being a medical missionary in an emerging nation suggests exposure to infectious agents that can cause granulomas, such as tuberculosis. The presence of acid-fast organisms on sputum stains further supports this possibility. Additionally, the chest x-ray findings of multifocal nodules, some of which are cavitated, are consistent with granulomatous inflammation seen in tuberculosis.

2. Which description below best describes colorless fungal fiaments?

Oval budding cel!s

Derrnatophytic pseuciohyphae

Dimorphic fungi

Hyaline hyphae

Clernatiaceous hyphae

Luminescent trophozoites

Hyaline hyphae refers to fungal filaments that are transparent or colorless. This description fits the term "colorless fungal filaments" mentioned in the question. The other options, such as oval budding cells, dermatophytic pseudohyphae, dimorphic fungi, clernatiaceous hyphae, and luminescent trophozoites, do not accurately describe colorless fungal filaments.

Explanation

Hyaline hyphae refers to fungal filaments that are transparent or colorless. This description fits the term "colorless fungal filaments" mentioned in the question. The other options, such as oval budding cells, dermatophytic pseudohyphae, dimorphic fungi, clernatiaceous hyphae, and luminescent trophozoites, do not accurately describe colorless fungal filaments.

3. A 49-year-old woman has a high fever and a productive cough for 3 days. Her sputum is copious and yellow. Crackles are audible bilaterally at both lung bases and chest x-rays reveal patchy pulmonary infiltrates. Which of the following would most likely be found in greatest number in her sputum specimens?

Eosinophils

Neutrophils

Fibroblasts

Macrophages

Mast cells

Neutrophils would most likely be found in the greatest number in the woman's sputum specimens. Neutrophils are a type of white blood cell that are involved in the body's immune response to infection. They are typically the first cells to arrive at the site of infection and help to fight off bacteria. In this case, the woman's symptoms of high fever, productive cough, and lung infiltrates suggest a bacterial infection in the lungs, which would activate neutrophils to migrate to the area and help clear the infection.

Explanation

Neutrophils would most likely be found in the greatest number in the woman's sputum specimens. Neutrophils are a type of white blood cell that are involved in the body's immune response to infection. They are typically the first cells to arrive at the site of infection and help to fight off bacteria. In this case, the woman's symptoms of high fever, productive cough, and lung infiltrates suggest a bacterial infection in the lungs, which would activate neutrophils to migrate to the area and help clear the infection.

4. A pathologist receives a surgical specimen taken from a 12-year-old boy. The submitted history is not helpful. The specimen is processed for histopathology and the pathologist submits the following report. The specimen was one cm in diameter and nodular. The cut surface revealed a central region of white creamy material surrounded by a rim of firm tissue. Microscopically, the central region consisted of neutrophils, some of which were apoptotic. The neutrophils were surrounded by a capsule of proliferating granulation tissue. What is your diagnosis?

Abscess

Benign neoplasm

Cellulitis

Granuloma

Infarct

The given description of the surgical specimen, including the presence of a central region of white creamy material surrounded by a rim of firm tissue, along with the microscopic findings of neutrophils surrounded by a capsule of proliferating granulation tissue, is consistent with an abscess. An abscess is a localized collection of pus that forms as a result of an infection. The presence of neutrophils and apoptotic neutrophils further supports the diagnosis of an abscess, as neutrophils are typically involved in the inflammatory response to infection.

Explanation

The given description of the surgical specimen, including the presence of a central region of white creamy material surrounded by a rim of firm tissue, along with the microscopic findings of neutrophils surrounded by a capsule of proliferating granulation tissue, is consistent with an abscess. An abscess is a localized collection of pus that forms as a result of an infection. The presence of neutrophils and apoptotic neutrophils further supports the diagnosis of an abscess, as neutrophils are typically involved in the inflammatory response to infection.

5. A 45-year old man from Missouri was referred to the hospital with a 3-week history of fever, cough, shortness of breath and fatigue. The patient has been diagnosed with AIDS S years previously. A routine direct examination of a blood smear is shown below. Which of the following is the growth form of the most probable causative pathogen?

A thermally dimorphic fungus, mould form at 37°C (99°F), and in yeast form at 25°C (77°F)

A thermally dimorphic fungus, mould form at 25°C (77°F) and yeast form at 37°C (99°F)

A polymorphic yeast, producing yeast cells, hyphae and pseudohyphae

A monomorphic sporocarp

A dimorphic sporocarp

The correct answer is "A thermally dimorphic fungus, mould form at 25°C (77°F) and yeast form at 37°C (99°F)". This answer suggests that the causative pathogen is a thermally dimorphic fungus, meaning it can exist in two different forms depending on the temperature. At 25°C, it takes the form of a mould, and at 37°C, it takes the form of a yeast. This information is important in identifying the pathogen and determining the appropriate treatment for the patient.

Explanation

The correct answer is "A thermally dimorphic fungus, mould form at 25°C (77°F) and yeast form at 37°C (99°F)". This answer suggests that the causative pathogen is a thermally dimorphic fungus, meaning it can exist in two different forms depending on the temperature. At 25°C, it takes the form of a mould, and at 37°C, it takes the form of a yeast. This information is important in identifying the pathogen and determining the appropriate treatment for the patient.

6. A severely neutropenic transplant has died from pulmonary hemorrhage due to hyphae invading the pulmonary blood vessels resulting in infarct and major hemorrhage. Which of these fungi could do this?

Blastornyces

Aspergillus

Sporothrix

Histoplasma

Cocciclioides

Aspergillus is a fungus that can invade the pulmonary blood vessels, leading to infarction and major hemorrhage. This can cause pulmonary hemorrhage, which is the cause of death in this case. Blastomyces, Sporothrix, Histoplasma, and Coccidioides are other types of fungi that can cause infections, but they are not typically associated with invading pulmonary blood vessels and causing pulmonary hemorrhage.

Explanation

Aspergillus is a fungus that can invade the pulmonary blood vessels, leading to infarction and major hemorrhage. This can cause pulmonary hemorrhage, which is the cause of death in this case. Blastomyces, Sporothrix, Histoplasma, and Coccidioides are other types of fungi that can cause infections, but they are not typically associated with invading pulmonary blood vessels and causing pulmonary hemorrhage.

7. Clostridium difficile is an important cause of nosocomiai diarrhea and disease in C. difficile colitis is mediated by toxins produced by the organism. Which type of laboratory test would be the most rapid and efficient way of confirmng infection with this organism?

Cultivation of the microbe on semi-solid media

Detection of the patient's immune response against the organism

Cultivation of the microbe in cell lines

Detection of the toxin produced by the organism

Gram stain of specimen

Detection of the toxin produced by the organism would be the most rapid and efficient way of confirming infection with Clostridium difficile. This is because the disease in C. difficile colitis is mediated by toxins produced by the organism. Therefore, detecting the presence of these toxins directly would provide a direct confirmation of the infection. Other methods such as cultivation of the microbe or detection of the patient's immune response may take longer and may not be as specific for confirming the infection. Gram stain of the specimen may provide some information about the presence of the organism, but it does not directly confirm the infection or the production of toxins.

Explanation

Detection of the toxin produced by the organism would be the most rapid and efficient way of confirming infection with Clostridium difficile. This is because the disease in C. difficile colitis is mediated by toxins produced by the organism. Therefore, detecting the presence of these toxins directly would provide a direct confirmation of the infection. Other methods such as cultivation of the microbe or detection of the patient's immune response may take longer and may not be as specific for confirming the infection. Gram stain of the specimen may provide some information about the presence of the organism, but it does not directly confirm the infection or the production of toxins.

8. Clostridium perfringens is notable for causing gas gangrene. Which other condition is this bacterium associated with?

A) A life threatening diarrheat illness associated with Type A bacteria

B) A self limiting, acute, diarrheal illness associated with Type C bacteria

C) A sometimes fatal disease called enteritis necrotans associated with Type A bacteria

D) A self limiting, acute, diarrheal illness associated with Type A bacteria

E) A chronic, diarrheal illness associated with Type A bacteria

Clostridium perfringens is associated with a self-limiting, acute, diarrheal illness caused by Type A bacteria. This bacterium is known to produce toxins that can cause gastrointestinal symptoms such as diarrhea, abdominal cramps, and nausea. The illness typically resolves on its own within a few days without any specific treatment. Gas gangrene, on the other hand, is a different condition caused by Clostridium perfringens that affects the muscles and soft tissues and is characterized by severe pain, swelling, and tissue death.

Explanation

Clostridium perfringens is associated with a self-limiting, acute, diarrheal illness caused by Type A bacteria. This bacterium is known to produce toxins that can cause gastrointestinal symptoms such as diarrhea, abdominal cramps, and nausea. The illness typically resolves on its own within a few days without any specific treatment. Gas gangrene, on the other hand, is a different condition caused by Clostridium perfringens that affects the muscles and soft tissues and is characterized by severe pain, swelling, and tissue death.

9. A patient is scheduled to have a chronic abscess incised and drained. What would you expect microscopic examination of the contents of the abscess to most likely show?

A chronic inflammatory infiltrate of lymphocytes and macrophages

An area of liquefactive necrosis

A chronic inflammatory infiltrate of neutrophils, lymphocytes, macrophages & plasma cells

An acute inflammatory infiltrate of primarily neutrophils

A chronic inflammatory infiltrate of primarily neutrophils

Microscopic examination of the contents of a chronic abscess would most likely show a chronic inflammatory infiltrate of neutrophils, lymphocytes, macrophages, and plasma cells. This is because chronic abscesses are characterized by a prolonged inflammatory response, with the presence of various immune cells. Neutrophils are typically the first immune cells to arrive at the site of infection, followed by lymphocytes, macrophages, and plasma cells. This combination of immune cells indicates a chronic inflammatory process.

Explanation

Microscopic examination of the contents of a chronic abscess would most likely show a chronic inflammatory infiltrate of neutrophils, lymphocytes, macrophages, and plasma cells. This is because chronic abscesses are characterized by a prolonged inflammatory response, with the presence of various immune cells. Neutrophils are typically the first immune cells to arrive at the site of infection, followed by lymphocytes, macrophages, and plasma cells. This combination of immune cells indicates a chronic inflammatory process.