0% Micro USMLE 8-30(21) (qmax 8/29 incorrect qs) Flashcards
For an HIV-infected patient, findings of fever, headache, altered mental status, vision changes, and an elevated opening pressure on lumbar puncture should raise concerns for an infectious intracranial process. In a patient who is noncompliant with medications and has had exposure to pigeon droppings (based on her gardening in a park), the primary concern is Cryptococcus neoformans meningoencephalitis. C. neoformans meningoencephalitis is acquired by inhaling dust from soil contaminated with bird droppings, particularly those of pigeons. This is an AIDS-defining illness, because it generally does not occur until the CD4+ cell count is <50. Under the microscope, Cryptococcus appears as ?
a heavily encapsulated nondimorphic yeast with narrow-based budding on India ink stain
Broad-based budding yeast refers to Blastomyces. Blastomyces is found in wooded areas east of the Mississippi River.
Budding yeast with pseudohyphae refers to?
Candida albicans, which can cause thrush, vulvovaginitis, and numerous other mucocutaneous infections.
Mold with hyphae that branch at 45-degree angles refers to Aspergillus fumigatus, which more commonly infects individuals with underlying pulmonary disease or those working in construction (due to inhalation exposure).
Small intracellular yeast refers to Histoplasma, a fungus found in the Mississippi and Ohio River valleys.
In a patient with HIV infection, neurologic symptoms, and an increased opening pressure on lumbar puncture suggest meningoencephalitis due to infection with Cryptococcus neoformans. Cryptococcus is an ?
encapsulated yeast with narrow-based budding, and cryotococcosis is an AIDS-defining illness.
This patient has the classic presentation for diphtheria, a grayish white pseudomembrane on the pharynx or tonsils (see image). Other symptoms of diphtheria, which is caused by the gram-positive rod Corynebacterium diphtheriae, include sore throat, malaise, and cervical lymphadenopathy. Fever is usually mild or absent. The pseudomembrane associated with this infection should not be disrupted to prevent increased absorption of the lethal exotoxin produced by this organism.
Diphtheria is rarely observed in vaccinated populations but is endemic to certain parts of the world. Moreover, cases may be seen in any?
developing country. Löffler medium and tellurite agar can be used in conjunction for culture and subsequent diagnosis of C. diptheriae infection
A patient with pharyngitis and a pseudomembrane on the pharynx is likely infected with C. diphtheriae, which is best cultured on a ?
Löffler medium in combination with tellurite agar. Other symptoms of infection include a sore throat, cervical lymphadenopathy, and low-grade fever.
This patient presents with nausea, abdominal cramping, bloating, and watery diarrhea. Although a number of bacterial and viral infections can manifest with such symptoms, the patient’s recent camping trip suggests that he has been infected with Giardia lamblia. Colonization of the gut by Giardia trophozoites results in?
small bowel inflammation and villous atrophy, which reduces absorptive capability. The image of the duodenal aspirate reveals a pear-shaped trophozoite.
Giardia trophozoites can lead to small bowel inflammation and villous atrophy, resulting in ?
reduced absorptive capability and malabsorption. Giardia infection is diagnosed by duodenal aspiration.
This pregnant woman presents with jaundice and complains of nausea, vomiting, fever, and abdominal pain. These symptoms and the patient’s recent travel to rural India indicate that hepatitis E virus (HEV) is the most likely cause of this patient’s disease. Hepatitis A virus (HAV), however, may also be a possibility. Both are ?
single-stranded linear RNA viruses transmitted via the fecal-oral route that are endemic in developing countries.
Most cases of sporadic acute viral hepatitis E are self-limiting and not associated with chronic liver disease or persistent viremia. Yet hepatitis E is notable for its predilection to cause fulminant hepatic failure in pregnant patients. One of the characteristic features of the infection is the high mortality rate among pregnant women, which approaches 20%.
The concern for this 2-month-old infant is meningitis, which can be caused by bacteria, viruses, or fungi. The classic symptom triad is fever, headache, and nuchal rigidity. In an infant with an open fontanelle, there will be no nuchal rigidity, but the open fontanelle will appear to bulge. Other symptoms such as rash and photophobia are also commonly present. Inference from the history, such as severe crying in a normally quiet baby, may indicate headache or muscle stiffness.
A lumbar puncture and cerebrospinal fluid (CSF) analysis is essential in determining the cause. Classic CSF findings for bacterial meningitis are elevated opening pressure, elevated levels of polymorphonuclear leukocytes, elevated protein levels, and decreased glucose levels, as seen in this patient. In newborns age 0–6 months old, the three most common causes of meningitis are all bacterial and include?
group B Streptococci, Escherichia coli, and Listeria monocytogenes. Culture and microbiology analysis can differentiate among these species.
In newborns and babies, the meningitis symptoms of fever, headache, and neck stiffness may be absent or difficult to notice. However, the mortality rate for untreated meningitis is high, and patients can quickly deteriorate. Therefore, empiric treatment should be initiated prior to obtaining the results of CSF analysis.
Group B streptococci, E. coli, and Listeria monocytogenes are the most common causes of ?
meningitis in children 0–6 months old. In newborns and babies, the meningitis symptoms of fever, headache, and neck stiffness may be absent or difficult to notice. Definitive diagnosis can be made based on CSF analysis, with meningeal inflammation demonstrated by increased WBC count, elevated protein level, and low glucose level in the CSF.
A transplant patient presents with a fever, decreased SpO2, shortness of breath, non-productive cough, nausea, vomiting, and tachypnea. Because of these symptoms and her transplant history, she should be suspected of having?
cytomegalovirus (CMV) pneumonitis, which is a common complication in immunocompromised patients after receiving a lung transplant, solid organ transplant or a bone marrow transplantation and occurs typically 1-4 months post-transplant.
Radiographic manifestations of CMV pneumonia are most commonly seen as bilateral, symmetrical, peribronchovascular, and alveolar processes occurring predominantly in the lower lobes, as in this patient. However, it can cause a focal consolidation or a solitary pulmonary nodule, but this is more suggestive of a bacterial or fungal infection. Histopathology shows large cells with intranuclear basophilic inclusions (?owl’s eyes?—see black arrow in image below) and are pathognomonic of CMV infection. CMV is an enveloped, double stranded linear DNA virus that is ?
latent in mononuclear cells. This patient’s history as well as radiographic and histologic findings make CMV the most likely causative organism.
Cytomegalovirus (CMV) is an enveloped double stranded linear DNA virus that is ?
latent in mononuclear cells. It is seen histologically as large cells with intranuclear inclusions (“owl′s eyes”) and is a common cause of pneumonia in immunocompromised patients, especially those 1-4 months post-transplant.
This patient is admitted to the hospital in status asthmaticus, and mechanical ventilation is initiated after he experiences acute respiratory failure. After 96 hours, the patient requires additional ventilatory support. He has also developed a fever and tracheobronchial secretions. X-ray of the chest reveals a right lower lobe infiltrate. This patient likely has ventilator-associated pneumonia (VAP), a common complication among patients requiring ventilation. Sedative medications required during intubation depress the native ciliary elevator function of natural respiration, leading to VAP. Symptoms include fever or hypothermia, new purulent sputum, or a change in respiratory support requirements. In order for VAP to be diagnosed, a patient must have been receiving mechanical ventilation for at least 48 hours. Both chronic lung disease and convalescence in the intensive care unit are risk factors for VAP. It is often caused by?
the gram-negative bacillus Pseudomonas aeruginosa. For this reason, empiric antibiotic therapy for VAP, such as piperacillin-tazobactam, must be prescribed to cover Pseudomonas.
Sedative medications required for intubation can cause depression of native ciliary elevator function of natural respiration. This increases a patient’s susceptibility to certain respiratory pathogens and can lead to ?
VAP. P. aeruginosa is the organism most commonly associated with VAP.
