Infectious Diseases

A 24-year-old medical student accidentally sustains a percutaneous needlestick injury from a hollow-bore needle immediately after drawing blood from a hospitalized patient. The source patient's human immunodeficiency virus (HIV), hepatitis B, and hepatitis C statuses are currently unknown. Arrange the following steps in the most appropriate chronological sequence for the immediate management of this occupational exposure.

Match the following classic dermatological findings with the infectious disease they most accurately represent.

A $52$-year-old man is evaluated for persistent fever. He was admitted $20$ days ago for acute myeloid leukemia induction chemotherapy, which resulted in profound bone marrow suppression. Ten days ago, his absolute neutrophil count dropped to $50/\text{mm}^3$ and he developed a fever of $39.1^\circ\text{C}$ ($102.4^\circ\text{F}$). Blood cultures were drawn, and empiric intravenous cefepime was initiated. He remained febrile, and $5$ days ago, intravenous vancomycin was added.

Today, his temperature is $38.6^\circ\text{C}$ ($101.5^\circ\text{F}$). He reports new-onset right-sided pleuritic chest pain. His absolute neutrophil count remains at $50/\text{mm}^3$. Repeated blood cultures drawn prior to the initiation of antibiotics and $5$ days ago have shown no growth. A non-contrast computed tomography scan of the chest reveals a $3\text{ cm}$ dense macronodule surrounded by a halo of ground-glass attenuation in the right upper lobe. Serum galactomannan testing is strongly positive, and intravenous voriconazole is initiated.

Which of the following is the most appropriate next step regarding this patient's antibacterial regimen?

Match each clinical presentation of an immunocompromised patient with the most appropriate targeted pharmacotherapy.

A 58-year-old man is brought to the emergency department by his family due to fever, severe headache, and progressively worsening confusion that started 12 hours ago. He has a history of type 2 diabetes mellitus and hypertension. His temperature is 39.2°C (102.6°F), blood pressure is 142/86 mmHg, pulse is 112/min, and respirations are 18/min. Physical examination reveals marked nuchal rigidity. Neurologic examination shows a lethargic patient who only opens his eyes to painful stimuli. He demonstrates a new-onset left-sided pronator drift. Arrange the following management steps in the most appropriate chronological order for this patient.

An oncology clinic evaluates a patient undergoing induction chemotherapy for acute myeloid leukemia who developed chills and a high temperature earlier today. The patient reports generalized weakness but denies cough, dysuria, abdominal pain, or skin changes. Vital signs show a temperature of $38.7^\circ\text{C}$ ($101.7^\circ\text{F}$), blood pressure of $118/76\text{ mmHg}$, heart rate of $105/\text{min}$, and respiratory rate of $16/\text{min}$. Physical examination is unremarkable, with clear lung fields and no induration or erythema at the central venous catheter site. Laboratory studies reveal a total leukocyte count of $800/\text{mm}^3$ with $10\%$ neutrophils and $5\%$ bands. After obtaining appropriate blood and urine cultures, which of the following is the most appropriate empiric pharmacotherapy?

A $42$-year-old man with a history of advanced HIV infection (CD4 count $85/\text{mm}^3$) is brought to the emergency department by his partner due to $3$ days of high fever, severe generalized headache, and progressive lethargy. His temperature is $39.1^\circ\text{C}$ ($102.4^\circ\text{F}$), blood pressure is $115/75 \text{ mmHg}$, pulse is $110/\text{min}$, and respirations are $18/\text{min}$. Physical examination reveals a lethargic man who is oriented only to person. He has pronounced resistance to passive neck flexion. Cranial nerve examination is notable for an inability to abduct the right eye. The remainder of the examination is unremarkable. Arrange the following steps in the most appropriate sequential order for the management of this patient.

Paramedics bring a 35-year-old previously healthy male to the emergency department after he was found lethargic at home. His wife reports he has been complaining of an excruciating diffuse headache and photophobia since yesterday. Vital signs show a temperature of 39.2°C (102.6°F), pulse of 118/min, and blood pressure of 105/65 mmHg. Neurologic examination demonstrates a depressed level of consciousness and clear bilateral papilledema. The care team suspects acute bacterial meningitis and prepares to manage the patient. Arrange the following interventions in the correct procedural sequence.

A 56-year-old woman is evaluated in the hospital on the third day of her admission for acute complicated pyelonephritis. On presentation to the emergency department, she had severe right flank pain, a temperature of 39.2°C (102.6°F), and a blood pressure of 90/60 mm Hg. After initial intravenous fluid resuscitation, her hemodynamics normalized, and she was admitted to the medical ward. She was empirically started on intravenous cefepime and vancomycin. Today, the patient reports that her flank pain has nearly resolved. She has been afebrile for the past 24 hours and is tolerating a regular diet without nausea or vomiting. Her current blood pressure is 122/78 mm Hg and pulse is 76/min. Blood and urine cultures obtained on admission both grow Escherichia coli. Susceptibility testing indicates the isolate is resistant to ampicillin but susceptible to ceftriaxone, piperacillin-tazobactam, ciprofloxacin, and trimethoprim-sulfamethoxazole. Which of the following is the most appropriate next step in the management of this patient's infection?

A 52-year-old man was admitted to the hospital 3 days ago for acute pyelonephritis. At the time of admission, he presented with a temperature of $39.1^\circ\text{C}$ ($102.4^\circ\text{F}$), left-sided costovertebral angle tenderness, and leukocytosis. He was empirically started on intravenous piperacillin-tazobactam. Currently, he has been afebrile for 24 hours, his flank pain has largely resolved, and he is eating a regular diet without nausea. The urine culture obtained on admission has grown $>100,000\text{ CFU/mL}$ of *Escherichia coli*. Antimicrobial susceptibility testing indicates the isolate is susceptible to trimethoprim-sulfamethoxazole, levofloxacin, ceftriaxone, and piperacillin-tazobactam. Which of the following is the most appropriate next step in the management of this patient's infection?

Match each sexually transmitted pathogen with its characteristic primary clinical presentation.

Match each clinical presentation of a vector-borne or zoonotic illness with its most appropriate first-line antimicrobial regimen.

Evaluate the following distinct clinical vignettes detailing patients with specific environmental or occupational exposures. Match each patient's presentation with the most likely causative zoonotic pathogen.

A $35$-year-old man comes to the clinic with a rash on his right thigh. He first noticed it $3$ days ago, and it has been expanding. He returned from a camping trip in Massachusetts one week ago. He feels well otherwise and denies fever, joint pain, or headaches. His temperature is $37.2^\circ\text{C}$ ($99.0^\circ\text{F}$), blood pressure is $120/80$ mmHg, and pulse is $76$/min. Physical examination shows a $10$-cm erythematous annular plaque with central clearing on the right thigh. Which of the following is the most appropriate next step in management?

A 52-year-old man is evaluated in the hospital on day 3 of admission for severe right lower extremity cellulitis and fever. On presentation to the emergency department, his temperature was $39.2^\circ\text{C}$ ($102.6^\circ\text{F}$) and his blood pressure was $92/58\text{ mmHg}$. Blood cultures were drawn, and he was empirically started on intravenous vancomycin and piperacillin-tazobactam along with fluid resuscitation. Today, his temperature is $37.3^\circ\text{C}$ ($99.1^\circ\text{F}$), his blood pressure is $124/78\text{ mmHg}$, and the erythema and induration of his right leg have significantly decreased. The admission blood cultures are now growing *Staphylococcus aureus* in both sets. Susceptibility testing demonstrates that the organism is resistant to penicillin, but susceptible to oxacillin, cefazolin, and vancomycin. Which of the following is the most appropriate next step in this patient's pharmacotherapy?

A 59-year-old woman is evaluated in the hospital on day 3 of admission for acute cholangitis. She initially presented with fever, right upper quadrant pain, and jaundice. She underwent an uncomplicated endoscopic retrograde cholangiopancreatography (ERCP) with stone extraction on the day of admission and was started on empiric piperacillin-tazobactam and vancomycin. She is currently afebrile and her hemodynamics are stable.

Blood cultures drawn on admission are now positive for *Klebsiella aerogenes*. Antimicrobial susceptibility testing is reported as follows:

Which of the following is the most appropriate definitive pharmacotherapy for this patient?

A 24-year-old woman presents to the university health clinic reporting two days of severe burning upon urination and a sensation of needing to urinate frequently. She denies any fever, chills, flank pain, nausea, or vaginal discharge. Her medical history is unremarkable, and she takes no daily medications other than an oral contraceptive pill. Vital signs include a temperature of 37.1°C (98.8°F), blood pressure of 118/76 mmHg, and a heart rate of 78/min. Physical examination reveals mild suprapubic tenderness but no costovertebral angle tenderness. A clean-catch urinalysis is positive for leukocyte esterase and nitrites, with >50 white blood cells per high-power field. A urine culture is pending. Which of the following is the most appropriate empiric pharmacotherapy for this patient?

Evaluate the following clinical scenarios of patients diagnosed with infective endocarditis. Pair each patient profile with the most appropriate definitive antimicrobial regimen based on current treatment guidelines.

A $64$-year-old man is evaluated in the intensive care unit for a persistent fever. He was admitted $8$ days ago for a severe exacerbation of chronic obstructive pulmonary disease and required endotracheal intubation on the second day of admission. Four days ago, he developed a new fever, worsening oxygenation, and thick endotracheal secretions. Blood and lower respiratory tract cultures were obtained, and empiric therapy with intravenous piperacillin-tazobactam and vancomycin was initiated. Today, his temperature is $38.7^\circ\text{C}$ ($101.7^\circ\text{F}$), blood pressure is $112/68\text{ mm Hg}$, pulse is $102/\text{min}$, and leukocyte count is $16,500/\text{mm}^3$. Blood cultures have remained sterile. The endotracheal aspirate culture grows \textit{Enterobacter cloacae}. Antimicrobial susceptibility testing shows the isolate is susceptible to ceftriaxone, ceftazidime, cefepime, piperacillin-tazobactam, and meropenem, but resistant to ampicillin and cefazolin. Which of the following is the most appropriate next step in the pharmacologic management of this patient?

A 74-year-old man is admitted to the intensive care unit with septic shock secondary to a severe complicated urinary tract infection. He has a history of neurogenic bladder managed with clean intermittent catheterization. On admission, his temperature is $39.2^\circ\text{C}$ ($102.6^\circ\text{F}$), blood pressure is $82/50\text{ mmHg}$, and heart rate is $118/\text{min}$. He receives aggressive fluid resuscitation and is started on empiric intravenous piperacillin-tazobactam and vancomycin. By hospital day 3, his condition has significantly improved; he is afebrile, hemodynamically stable off vasopressors, and transferred to the general medical floor. Blood cultures and a urine culture obtained on admission both yield *Enterococcus faecalis*. Susceptibility testing indicates the organism is sensitive to ampicillin, vancomycin, linezolid, and daptomycin, but intrinsically resistant to cephalosporins. Which of the following is the most appropriate next step in pharmacotherapy?