A 67-year-old man comes to the emergency department due to abdominal cramps, diarrhea, and fever that started 3 days ago.  The patient initially had 3 or 4 stools per day for 2 days but, today, had 7 watery stools; the stools have not had gross blood or mucus or black discoloration.  The patient has also had generalized weakness and malaise.  Two weeks ago, he was treated with oral antibiotics for acute cellulitis.  Since then, the patient’s appetite has decreased, and he has had mild bloating.  He has no history of recent travel, unusual foods, or sick contacts with similar symptoms.  Other medical conditions include type 2 diabetes mellitus, hypertension, and hyperlipidemia.  Temperature is 38.7 C (101.7 F), blood pressure is 110/70 mm Hg, and pulse is 95/min.  Physical examination shows moderate abdominal tenderness.  The cellulitis has resolved.  Leukocytes are 26,000/mm³, serum creatinine is 1.9 mg/dL (increased from 1.2 mg/dL 2 months ago), and serum albumin is 2.9 g/dL.  The patient does not want to be admitted to the hospital and would like to be treated as an outpatient.

Item 1 of 2

The patient is at most risk for developing which of the following complications?

Item 2 of 2
Stool PCR testing for Clostridioides difficile PCR is positive.  The patient is adamant about going home.  He is given a prescription for oral fidaxomicin and discharged home against medical advice.  The patient returns 2 days later feeling much worse.  He says, “I just got the pills today and have taken only one dose.”  Temperature is 38.9 C (102 F), blood pressure is 90/60 mm Hg, pulse is 114/min, and respirations are 24/min.  The patient appears uncomfortable.  The abdomen is distended, and bowel sounds are decreased; there is tenderness and guarding to palpation.  CT scan of the abdomen shows diffuse colonic wall thickening and dilation.  In addition to the appropriate oral pharmacotherapy, what is the most appropriate next step in management of this patient?

A 32-year-old woman comes to the emergency department due to 7 days of fever and dry cough.  She has also had progressive shortness of breath with minimal walking and climbing stairs.  The patient was diagnosed with HIV infection a year ago and is not currently on antiretroviral treatment.  She does not use tobacco, alcohol, or illicit drugs.  Temperature is 38.4 C (101.1 F), blood pressure is 110/64 mm Hg, pulse is 106/min, and respiratory rate is 26/min.  Pulse oxymetry is 87% on room air and decreases to 82% with minimal walking.  Oropharyngeal thrush is present.  Lung auscultation reveals scattered bilateral crackles and rhonchi.  The abdomen is soft and nontender without organomegaly.  No cyanosis, clubbing, or edema is present.  Chest x-ray reveals diffuse interstitial opacities bilaterally.  CD4 count is 85/mm³.  The patient is admitted and started on empiric therapy.  Twenty-four hours after admission, the induced sputum analysis is negative for Pneumocystis.

Item 1 of 3

Which of the following is the likely cause of this patient’s pneumonia?

Item 2 of 3

Which of the following is the most appropriate indication for the use of corticosteroids in this patient?

Item 3 of 3

On day 2 of hospitalization, the patient develops worsening dyspnea and hypoxia.  Repeat chest x-ray reveals worsened interstitial infiltrate.  Due to significant tachypnea and poor oxygenation, the patient is intubated.  The patient is currently receiving trimethoprim-sulfamethoxazole, prednisone, ceftriaxone, and azithromycin.  Blood cultures from admission are negative at 48 hours.  Which of the following is the best next step in management of this patient?

A 26-year-old man comes to the office after learning that one of his sexual partners tested positive for HIV.  The patient has had intermittent headaches, malaise, nausea, and blurry vision over the last several weeks.  He has had no fever, sore throat, skin rash, genital lesions, or weight loss.  The patient has no prior history of sexually transmitted infections or chronic medical problems.  He smokes a pack of cigarettes daily, consumes alcohol occasionally, and does not use illicit drugs.  The patient has had multiple sexual partners over the last several years and does not use condoms consistently.  Temperature is 37.1 C (98.8 F), blood pressure is 122/74 mm Hg, and pulse is 72/min.  There is no scleral icterus, oropharyngeal lesions, or skin rash.  Mild, generalized lymphadenopathy is present.  Cardiopulmonary and abdominal examinations are normal.  Cranial nerves, deep tendon reflexes, and sensation are normal.  No nuchal rigidity is present.  Ophthalmologic examination reveals no abnormalities.  Screening HIV immunoassay is positive.  Other laboratory studies are as follows:

A subsequent fluorescent treponemal antibody absorption test is positive.  Contrast-enhanced CT scan of the head reveals no space-occupying lesions.

Item 1 of 3

Which of the following is the most appropriate next step in management of this patient’s treponemal infection?

tem 2 of 3

Additional tests are performed and are normal.  Which of the following is the best treatment option?

Item 3 of 3

Several hours after the appropriate treatment for the syphilis is administered, the patient develops a fever and headache and feels “achy all over.”  On repeat evaluation, temperature is 38.1 C (100.6 F), blood pressure is 130/82 mm Hg, and pulse is 105/min.  The remainder of the physical examination is unchanged.  Which of the following could have prevented this patient’s current condition?

A 24-year-old man comes to the clinic because he “feels terrible and can barely get out of bed.”  Two days ago, he started feeling feverish and sweaty.  He then developed persistent headache, fatigue, sore throat, and aching in his muscles and joints.  The patient has no chronic medical issues and takes no medications.  He has been sexually active with 2 women over the past few months and rarely uses condoms.  The patient smokes a pack of cigarettes and drinks 2-4 alcoholic beverages daily.  Temperature is 38.6 C (101.5 F), blood pressure is 130/88 mm Hg, pulse is 94/min, and respirations are 16/min.  The patient is ill-appearing with flushed, damp skin.  An erythematous maculopapular rash is present on his face, trunk, palms, and soles.  Oropharyngeal examination shows a shallow, tender ulcer with white exudate on the posterior oropharynx.  Several enlarged, discrete, mobile lymph nodes are present in the cervical, axillary, and occipital regions.  Lung auscultation is unremarkable, and heart sounds are normal.  The abdomen is soft, nontender, and nondistended with no hepatosplenomegaly.  Laboratory results are as follows:

Which of the following is the most likely cause of this patient’s current symptoms?

A 42-year-old man comes to the hospital with a 4-day history of periodic fever, chills, headache, and myalgias.  For the past day, he also had mild abdominal discomfort, nausea, and vomiting.  The patient has no chest pain, cough, dyspnea, or diarrhea.  He returned from an African safari 2.5 weeks ago, and family members who traveled with him have no symptoms.  The patient has no past known medical problems.  His temperature is 39.4 C (103 F), blood pressure is 122/70 mm Hg, and pulse is 114/min and regular.  On examination, he is diaphoretic and uncomfortable.  There is mild pharyngeal erythema without exudates or lymphadenopathy.  Cardiopulmonary examination is normal.  There is no neck stiffness.  The abdomen is soft with mild generalized tenderness and splenomegaly.  He has no skin rash.  Neurologic examination is normal.

Laboratory results are as follows:

Chest x-ray reveals no abnormalities.  Which of the following interventions could have prevented his current condition?

A 33-year-old man with no prior medical history comes to the emergency department due to abdominal discomfort that began 24 hours ago.  He describes the discomfort as a dull ache in his abdomen that is accompanied by nausea and malaise.  Approximately 3 weeks ago, he abruptly developed pain in his hands, ankles, and knees.  This was quickly followed by a pruritic rash that initially involved only his lower abdomen but then spread to his entire trunk and extremities.  He also had low-grade fevers over the same period.  He has had no recent travel or insect bites but reports using intravenous heroin over the last year.  Temperature is 38.3 C (100.9 F), blood pressure is 120/70 mm Hg, pulse is 92/min, and respirations are 14/min.  Examination shows moist mucous membranes and poor dentition with no lesions in the oropharynx.  Lung fields are clear with normal S1 and S2.  The abdomen is soft and mildly tender in the right upper quadrant with a palpable liver 3 cm below the costal margin.  The joints of his hands, ankles, and knees are diffusely tender to palpation but without erythema or edema.  Scattered skin lesions that are raised, erythematous, and well-defined are noted over his trunk and extremities.  Laboratory results are as follows:

Which of the following has the most similar pathophysiological mechanism to that of this patient’s current condition?

A 30-year-old man is seen in the office due to recently diagnosed HIV infection.  The patient did not previously have testing for HIV, and the duration of infection is unknown.  He is asymptomatic; physical examination is unremarkable.  Laboratory results are as follows:

The patient has had no vaccinations since learning of his HIV diagnosis.  Which of the following is indicated in this patient?

A 45-year-old female presents to your office with fever, malaise and facial rash.  The symptoms started acutely one day ago, and she took two tablets of ibuprofen to relieve the fever.  Her past medical history is insignificant.  She works as a clerk at a private office, and is not physically active.  She smokes two packs of cigarettes daily, and consumes alcohol occasionally.  She denies any recreational drug use.  She has no known allergies.  She is sexually active in a monogamous relationship with her husband.  The rash is shown below.

Other physical findings are within normal limits.  Which of the following is the most likely cause of this patient’s problem?

A 64-year-old woman with a known history of myasthenia gravis comes to the emergency department with 2 days of fever and worsening headaches and neck pain.  She was admitted to another hospital 8 days ago for myasthenic crisis precipitated by urinary tract infection.  She was treated with ceftriaxone and intravenous immunoglobulin and discharged home 3 days ago to complete a course of oral antibiotics.  Her other medical problems include hypertension and type 2 diabetes mellitus.  Her medications include metformin, glyburide, hydrochlorothiazide, lisinopril, and mycophenolate.  The patient’s temperature is 38.3 C (101 F), blood pressure is 110/70 mm Hg, pulse is 92/min, and respirations are 16/min.  She is awake and oriented.  Moderate neck pain and stiffness are present.  She moves all extremities to command and has symmetrical deep-tendon reflexes.  The remainder of the examination shows no abnormalities.  Laboratory results are as follows:

Cerebrospinal fluid Gram stain and culture show no organisms.  Cerebrospinal fluid cryptococcal antigen is negative.  CT scan of the head without contrast is normal.  Which of the following is the most likely cause of this patient’s symptoms?

A 19-year-old man comes to the student health center due to 2 days of burning pain during urination.  He has also had itching of the urethral meatus but no urinary discharge, fever, chills, or rash.  The patient has no chronic medical conditions and takes no medications.  He had unprotected sexual intercourse with a new female partner a week ago.  The patient has smoked a pack of cigarettes daily since age 14.  He drinks alcohol on weekends and does not use illicit drugs.  Vital signs are within normal limits.  There is scant, watery urethral discharge at the urethral meatus.  There are no genital ulcers, rashes, erythema, or inguinal lymphadenopathy.  Urethral swab is performed, and Gram stain of the urethral fluid reveals many neutrophils but no organisms.  Nucleic acid amplification tests of the urine are sent for Chlamydia trachomatis and Neisseria gonorrhoeae.

Item 1 of 2
This patient’s symptoms are most likely to respond to which of the following?

Item 2 of 2
The patient received treatment with a single dose of azithromycin but returns to the office 2 weeks later due to continued burning with urination.  Since his previous visit, he has had no urethral discharge, fever, chills, scrotal pain, rash, or additional sexual encounters.  Nucleic acid amplification testing from his prior visit was negative for Neisseria gonorrhoeae and Chlamydia trachomatis.  Screening for syphilis with rapid plasma reagin and for HIV with fourth-generation HIV testing was also negative.  No urethral discharge is present, and the remainder of the physical examination is normal.  Which of the following is the most appropriate next step in management of this patient?

A 52-year-old woman is brought to the emergency department due to a day of fever, lethargy, and skin lesions.  She is currently undergoing combination chemotherapy for diffuse large B-cell lymphoma, and her last treatment was 10 days ago.  Yesterday, the patient developed a red rash on her right thigh.  Within a few hours, a pustule formed in the center of the lesion, rapidly evolved into a dark bulla, and then ruptured and formed an ulcer.  A second, similar skin lesion arose shortly thereafter.  The patient has also had fever and chills and progressive weakness and lethargy.  Temperature is 38.9 C (102 F), blood pressure is 110/60 mm Hg, and pulse is 106/min.  She has an implanted central venous catheter with a subcutaneous port; the overlying skin is not erythematous or tender.  Cardiopulmonary auscultation reveals clear lung fields and no cardiac murmurs.  The abdomen is soft and nontender.  Skin examination shows a nontender, necrotic ulcer with an erythematous rim and yellow-green, purulent exudate on the right thigh.  There is another lesion with a hemorrhagic dark-bluish bulla and surrounding erythematous, indurated skin.  Leukocyte count is 800/mm³ with 10% neutrophils.

Item 1 of 2

Which of the following is the most likely cause of this patient’s skin lesions?

Item 2 of 2

Which of the following statements regarding this patient’s current condition is most accurate?