Infectious Diseases

Match each clinical presentation of a genital ulcer disease with its most appropriate first-line pharmacotherapy.

Match each clinical presentation of infective endocarditis with the most appropriate targeted diagnostic evaluation or therapeutic intervention.

A 62-year-old man is evaluated in the hospital on hospital day 3. He was initially admitted for high fever and rigors. His past medical history is significant for end-stage renal disease requiring hemodialysis via a right internal jugular tunneled catheter. Upon admission, peripheral and catheter-drawn blood cultures were obtained, and he was started on empiric antimicrobial therapy with intravenous vancomycin and piperacillin-tazobactam. Today, his temperature is 37.2°C (99.0°F), blood pressure is 128/76 mmHg, and heart rate is 82/min. The admission blood cultures are now positive for Staphylococcus aureus in 4 out of 4 bottles. Susceptibility testing reveals the isolate is resistant to penicillin, but susceptible to oxacillin, cefazolin, and vancomycin. A review of the patient's medical record indicates a documented allergy to amoxicillin, which the patient describes as a 'flat, red skin rash' that occurred several days into a treatment course 10 years ago, without associated pruritus, facial swelling, or difficulty breathing. Which of the following is the most appropriate modification to his current pharmacotherapy?

A $34$-year-old woman presents to the clinic for evaluation of a skin rash. She noticed the rash on her right posterior thigh $4$ days ago, and it has steadily increased in size. She recently returned from a camping trip in Maine. The patient reports mild fatigue and muscle aches but denies fever, joint swelling, or shortness of breath. Her temperature is $37.1^\circ\text{C}$ ($98.8^\circ\text{F}$), blood pressure is $120/78\text{ mm Hg}$, and pulse is $76\text{/min}$. Physical examination reveals a $10\text{-cm}$, annular, erythematous plaque with a central area of clearing on the right posterior thigh. The remainder of the examination is unremarkable. Which of the following is the most appropriate next step in management?

A 54-year-old man is evaluated in the intensive care unit for a new-onset fever. He was admitted 6 days ago following a severe motor vehicle collision that resulted in multiple rib fractures and a pulmonary contusion. He required endotracheal intubation and mechanical ventilation on the day of admission. Over the past 24 hours, he has developed a temperature of $38.9^\circ\text{C}$ ($102.0^\circ\text{F}$) and requires an increasing fraction of inspired oxygen ($\text{FiO}_2$) and positive end-expiratory pressure. Endotracheal suctioning yields thick, purulent secretions. A chest radiograph reveals a new right lower lobe consolidation. His leukocyte count is $16,500/\text{mm}^3$. A bronchoalveolar lavage is performed, and he is started on empiric intravenous vancomycin and cefepime. Two days later, his oxygenation has stabilized. The bronchoalveolar lavage fluid cultures grow $> 10^4 \text{ CFU/mL}$ of *Pseudomonas aeruginosa*. The isolate is susceptible to cefepime, piperacillin-tazobactam, and meropenem. No other organisms are isolated. Which of the following is the most appropriate next step in the pharmacologic management of this patient?

An 81-year-old female resident of a skilled nursing facility is currently recovering in the intensive care unit after presenting three days prior with severe distributive shock secondary to a catheter-associated urinary tract infection. On admission, she was hypotensive and tachycardic, and empiric antimicrobial therapy was initiated with intravenous vancomycin and piperacillin-tazobactam. Today, she is hemodynamically stable, off vasopressor support, and her temperature has normalized to 37.1°C (98.8°F). The indwelling urinary catheter was removed on the first day. Both the admission urine and blood cultures have grown *Escherichia coli*. The susceptibility report for the bloodstream isolate is provided below:

Based on the culture results and the patient's current clinical status, which of the following is the most appropriate definitive pharmacotherapy?

A $35$-year-old man who recently emigrated from a country with high tuberculosis endemicity presents to the emergency department. He reports a $6$-week history of a persistent, blood-tinged cough, subjective fevers, drenching night sweats, and a $6$-kg ($13$-lb) weight loss. While in the crowded triage area, he is actively coughing. His vital signs show a temperature of $38.2^\circ\text{C}$ ($100.8^\circ\text{F}$). Arrange the following steps in the most appropriate chronological order for the optimal management of this patient.

A 71-year-old man is evaluated in the intensive care unit regarding his antimicrobial regimen. He was admitted 12 days ago for acute respiratory distress syndrome secondary to a severe viral pneumonitis and required endotracheal intubation. Five days ago, his clinical status deteriorated with the development of a fever up to 39.4°C (102.9°F), worsening hypoxia, and thick, purulent endotracheal secretions. A chest radiograph at that time demonstrated a new dense consolidation in the left lower lobe. Empiric intravenous therapy with piperacillin-tazobactam, tobramycin, and vancomycin was initiated.

Today, the patient is clinically improving; he is afebrile (37.1°C [98.8°F]), and his ventilator settings have been significantly weaned. The quantitative bronchoalveolar lavage culture obtained five days ago exhibits heavy growth ($10^5$ CFU/mL) of *Pseudomonas aeruginosa*. Antimicrobial susceptibility testing indicates the organism is susceptible to piperacillin-tazobactam, cefepime, and ciprofloxacin, but resistant to tobramycin. No other organisms, including methicillin-resistant *Staphylococcus aureus* (MRSA), have been isolated. Blood cultures show no growth.

Which of the following is the most appropriate next step in this patient's pharmacotherapy?

Match each clinical presentation with the most appropriate first-line targeted or empiric antimicrobial therapy.

A $32$-year-old man comes to the clinic to establish care after recently testing positive for human immunodeficiency virus (HIV). He is currently asymptomatic and has no history of opportunistic infections. Vital signs are within normal limits. Physical examination reveals no lymphadenopathy, oral thrush, or skin lesions. Laboratory evaluation shows a CD4 T-lymphocyte count of $38/\mu\text{L}$ and an HIV RNA viral load of $280,000$ copies/mL. Serologic testing is positive for *Toxoplasma gondii* IgG antibodies. An interferon-gamma release assay is negative. An antiretroviral therapy (ART) regimen consisting of bictegravir, emtricitabine, and tenofovir alafenamide is initiated today. In addition to ART, which of the following is the most appropriate prophylactic antimicrobial regimen for this patient?

For each clinical presentation described below, select the most appropriate initial antimicrobial agent according to current guidelines.

An otherwise healthy 42-year-old male is evaluated in the ambulatory care center due to a painful swelling on his right thigh. The lesion has been progressively enlarging over the past three days. He takes no medications and has no significant past medical history. Vital signs demonstrate a temperature of 37.1°C (98.8°F), blood pressure of 122/78 mm Hg, and a heart rate of 74/min. Physical examination of the right anterior thigh reveals a 3-cm, highly tender, fluctuant, erythematous nodule with a central purulent punctum. There is no significant surrounding induration, and no regional lymphadenopathy is appreciated. Which of the following is the most appropriate next step in management?

A $62$-year-old man with poorly controlled type 2 diabetes mellitus is admitted to the hospital with a non-healing ulcer on the plantar aspect of his right foot. The ulcer is surrounded by $4$ cm of erythema and warmth. During physical examination, a sterile metal probe easily reaches the underlying bone. His temperature is $38.2^\circ\text{C}$ ($100.8^\circ\text{F}$), blood pressure is $130/80$ mm Hg, and pulse is $96$/min. Laboratory studies show a leukocyte count of $14,500/\text{mm}^3$. He is started on empiric intravenous vancomycin and piperacillin-tazobactam. A bone biopsy is performed on the second day of admission. By day $5$, his fever has resolved, and the erythema has significantly decreased. The bone biopsy cultures grow only Staphylococcus aureus, which is sensitive to oxacillin, cefazolin, and clindamycin, but resistant to penicillin. No Gram-negative bacilli or anaerobes are isolated. Which of the following is the most appropriate next step in pharmacotherapy?

Match each clinical vignette describing an immunocompromised patient with an infectious disease to the most appropriate targeted antimicrobial therapy, taking into account patient-specific contraindications.

A 62-year-old man is brought to the emergency department by his husband due to a 24-hour history of severe headache, high fever, and progressive confusion. He has a history of end-stage renal disease and underwent a deceased-donor renal transplantation 3 years ago. His current medications include tacrolimus, mycophenolate mofetil, and prednisone. His temperature is 39.2°C (102.6°F), blood pressure is 112/74 mmHg, pulse is 115/min, and respirations are 20/min. Physical examination reveals marked nuchal rigidity and lethargy. He is oriented to person only, but there are no focal neurologic deficits.

Arrange the following diagnostic and therapeutic steps in the most appropriate sequential order for the optimal management of this patient.

A 24-year-old man presents to the clinic complaining of a diffuse, nonpruritic maculopapular rash that involves his palms and soles, accompanied by mild malaise and generalized lymphadenopathy. He reports unprotected sexual contact with a new partner approximately ten weeks ago. You suspect a systemic sexually transmitted infection. Arrange the following steps in the most appropriate chronological order for the diagnostic evaluation, treatment, and ongoing management of this patient.

A 65-year-old woman is hospitalized due to a 2-day history of high fever, right-sided flank pain, and altered mental status. She has a history of poorly controlled type 2 diabetes mellitus and recurrent urinary tract infections. On admission, her temperature is 39.2°C (102.6°F), blood pressure is 88/56 mm Hg, pulse is 118/min, and respirations are 22/min. Physical examination is notable for severe right costovertebral angle tenderness. Laboratory studies show a leukocyte count of 18,500/mm³. Urinalysis is positive for leukocyte esterase, nitrites, and numerous leukocytes. Blood and urine cultures are obtained, and the patient is started on empiric intravenous piperacillin-tazobactam. Over the next 48 hours, her fever resolves, and her hemodynamics normalize.

Preliminary results from both blood and urine cultures grow *Enterobacter cloacae*. Antimicrobial susceptibility testing reveals the isolate is susceptible to ceftriaxone, cefepime, piperacillin-tazobactam, meropenem, and gentamicin. It is resistant to ciprofloxacin and trimethoprim-sulfamethoxazole. Which of the following is the most appropriate next step in antimicrobial therapy?

A 36-year-old man with a history of advanced, untreated HIV infection (CD4 count $28 \text{ cells/mm}^3$) is brought to the emergency department due to progressive confusion, severe headaches, and left-sided weakness over the past week. His temperature is $38.1^\circ\text{C}$ ($100.6^\circ\text{F}$). Neurologic examination reveals a dense left hemiparesis. MRI of the brain reveals multiple 1- to 2-cm ring-enhancing lesions in the right basal ganglia and frontal lobe with marked surrounding vasogenic edema causing a 4-mm midline shift. Serum *Toxoplasma gondii* IgG antibodies are positive.

Arrange the following clinical actions in the correct chronological sequence according to the standard management algorithm for this patient, assuming a complete lack of clinical or radiographic response to the first-line medical intervention.

A hospital's antimicrobial stewardship and infectious diseases teams are reviewing several complex cases involving severe adverse drug events. Match each patient's clinical presentation of an antimicrobial-induced complication to the specific pharmacologic agent most likely responsible.

A 28-year-old resident physician sustains a deep percutaneous needlestick injury to her thumb while drawing arterial blood from a patient. The patient has a known history of untreated HIV with a viral load of 250,000 copies/mL. The needle is visibly contaminated with the patient's blood. Arrange the following steps in the most appropriate chronological order for the management of this occupational exposure.