Micro USMLE 8-29(16) (qmax 8/24- 1-31) Flashcards
Fever, chills, flank pain, and costovertebral angle tenderness in the context of dysuria and increased urinary frequency suggests a diagnosis of pyelonephritis. Pyelonephritis is most commonly caused by infection ascending to the kidneys from the lower urinary tract. In rare cases, infections can spread to the kidney via the bloodstream. The diagnosis is based largely on clinical symptoms, combined with results from urinalysis and urine culture. Pyelonephritis is more common in women than men and is caused most often by?
Escherichia coli (a lactose-fermenting, gram-negative rod). E. coli can be found in 82% of cases in women and 73% of cases in men.
An oxidase-negative, lactose-nonfermenting, gram-negative rod describes proteus mirabilis, which is associated with struvite stones.
An oxidase-positive, lactose-nonfermenting, gram-negative rod describes pseudomonas aeruginosa in the context of nosocomial infections.
Gram-negative bacteria capable of catalyzing urea to ammonia like Proteus mirabilis and Ureaplasma urealyticum can cause ?
urinary tract infections and pyelonephritis, but are not the most common cause of community acquired pyelonephritis.
Novobiocin-resistant, coagulase-negative, gram-positive cocci in clusters refers to Staphylococcus saprophyticus, which commonly causes cystitis.
Pyelonephritis can present as fever, chills, flank pain, and costovertebral angle tenderness, combined with urinary symptoms such as dysuria and increased frequency. E. coli (a lactose-fermenting, gram-negative rod) is the most common cause of ?
pyelonephritis.
Many years ago this patient had tuberculosis (TB) as indicated by his positive PPD and his receipt of isoniazid therapy. He currently is experiencing cough, night sweats, and unintentional weight loss, all of which suggest a reactivation of tuberculosis. Hematogenous spread due to reactivation of a latent focus of Mycobacterium tuberculosis from a previous infection can lead to disseminated disease, also known as miliary TB.
Sometimes reactivation occurs spontaneously, but more often, it is the result of a ?
weakened immune system that is no longer able to contain the latent infection. Miliary TB demonstrates widespread seeding of the lungs with mycobacteria in a pattern that resembles millet seed. His chest x-ray clearly shows many small opacities distributed throughout the lung, indicated by arrows in the image, representing multiple fine granulomas.
Almost every organ can be infected with reactivated M tuberculosis, most commonly affected are the lungs (through reseeding), liver, bone marrow, spleen, adrenal glands, and meninges. The lesions in these organs on biopsy resemble those in the lungs: 1- to 2-mm yellowish granulomas. Miliary TB is the most deadly progression of the disease.
Bridging fibrous septae are characteristic of end-stage cirrhosis and represent the liver’s attempt at regenerating damaged hepatocytes. Diffuse nodularity is characteristic of long-standing cirrhosis. Centrilobular hemorrhagic necrosis is the result of?
inadequate oxygenation and is not associated with TB. Clear macrovesicular globules are characteristic of hepatic steatosis and do not contain any bacteria.
Patients with previous Mycobacterium tuberculosis infection are at risk of developing miliary TB, characterized by ?
1- to 2-mm granulomas in the lung, liver, bone marrow, spleen, adrenal glands, and meninges.
The patient presents with cognitive symptoms (deteriorating academic performance) and physical symptoms (generalized seizures and visual disturbances) which appear to be worsening. Based on the lab results and his medical history, the patient is most likely suffering from ?
subacute sclerosing panencephalitis. This is a rare progressive demyelinating disease, associated with chronic central nervous system infection with measles virus.
There is often a history of primary measles infection at an early age (approximately 2 years) followed by a latent interval of 6–8 years. Initial manifestations usually include poor school performance, mood and personality changes, and insomnia. Fever and headache do not occur. As the disease progresses, patients develop ?
progressive intellectual deterioration, focal and/or generalized seizures, myoclonus, ataxia, and visual disturbances. The cerebrospinal fluid (CSF) is acellular with normal or mildly elevated protein and markedly elevated gamma-globulin (>20% of total CSF protein). CSF anti-measles antibodies are also elevated. CT and MRI show evidence of multifocal white matter lesions (indicated by the arrows in this image), cortical atrophy, and ventricular enlargement.
Classic measles presentation includes cough, coryza, conjunctivitis, high fever, and a red maculopapular rash that spreads downward from the head. Koplik spots (1mm white-gray lesions on an erythematous base) are seen in the buccal mucosa, and Warthin-Finkeldey cells (giant multinucleated cells) in the respiratory secretions are pathognomonic for measles. Measles virus is caused by?
an ss-RNA virus with hemagglutinins on its surface (for adhesion) and matrix proteins (for viral assembly).
Herpes simplex virus type 2 causes genital herpes and aseptic meningitis acutely.
• Mumps presents with parotitis, orchitis, pancreatitis and aseptic meningitis.
• Neisseria meningitidis can cause bacterial meningitis.
• Rubella virus, or German measles, is characterized by ?
fever and upper respiratory symptoms that resolve with subsequent rash.
• Group A streptococcus (GAS) infection can cause pharyngitis and impetigo, which may result in post-infectious complications of rheumatic fever (pharyngitis only) and glomerulonephritis (pharyngitis or impetigo).
Subacute sclerosing panencephalitis is a rare complication of prior measles infection that causes ?
progressive neurologic disease leading to death. CSF exams usually reveal normal pressure, cell count, and total protein content. However, CSF globulin is almost always elevated, constituting up to 20%–60% of CSF protein.
This patient’s symptoms of hoarse voice, inspiratory stridor, and violent cough (seal-like barking cough), along with a chest x-ray demonstrating a positive “steeple sign” (narrowing of the subglottis), are consistent with a diagnosis of croup, a common respiratory tract infection in children (see table).
Croup is caused by the parainfluenza virus of the Paramyxoviridae family. Paramyxoviruses have an ?
envelope and a helical capsid. They are single-stranded, negative-sense, linear, nonsegmented RNA viruses. Other illnesses caused by paramyxoviruses include respiratory syncytial virus, measles, and mumps. A mnemonic for circular RNA viruses is Dhey Are Balls (Delta virus, Arenavirus, Bunyavirus). All other RNA viruses are linear.
Reoviruses contain double-stranded, linear RNA, and caliciviruses contain single-stranded, positive-sense, linear, nonsegmented RNA. Both reoviruses and caliciviruses can cause diarrhea, but not croup. Delta virus (hepatitis D virus) is a single-stranded, negative-sense, circular RNA virus that worsens hepatitis B infections. Orthomyxoviruses are?
single-stranded, negative-sense, linear, segmented RNA viruses, such as the influenza virus, which can cause chills, muscle aches, runny nose, headaches, and fatigue in addition to congestion, cough, and fever.
A “barking” cough, hoarse voice, inspiratory stridor, and a positive “steeple sign” on a chest x-ray are found in patients with croup. Croup is caused by the parainfluenza virus, which is ?
a single-stranded, negative-sense, linear, nonsegmented RNA virus.
his newborn girl has an umbilical purulent discharge, fever, irritability, diffuse flushing, and large fluid-filled blisters that rupture easily. Blood culture yields gram-positive cocci in clusters on Gram staining. Together these findings suggest Staphylococcal scalded skin syndrome (SSSS).
SSSS is caused by the release of ?
Two exotoxins (epidermolytic toxins A and B) from Staphylococcus aureus. Desmosomes (also called “macula adherens”) are responsible for binding epithelial cells to one another to form a coherent whole.
