Infectious Diseases

An otherwise healthy 45-year-old woman receives treatment in the inpatient ward for an acute complicated urinary tract infection with associated bacteremia. At the time of admission two days ago, she presented with fever, chills, and costovertebral angle tenderness, prompting the initiation of empiric intravenous piperacillin-tazobactam. Today, she has been afebrile for the past 24 hours, her flank pain has nearly resolved, and she is tolerating a regular diet. Final culture results from both blood and urine demonstrate growth of *Escherichia coli*. The susceptibility report indicates resistance to ampicillin, but susceptibility to ceftriaxone, trimethoprim-sulfamethoxazole, levofloxacin, and piperacillin-tazobactam. Based on the culture results and the patient's clinical improvement, what is the most appropriate next step in management?

A $25$-year-old man presents to the clinic with a diffuse maculopapular rash on his trunk, palms, and soles, along with generalized lymphadenopathy. He reports having a painless penile ulcer $2$ months ago that resolved on its own. Assuming the traditional testing algorithm is used, arrange the following steps in the most appropriate chronological sequence for the diagnosis and management of this patient's condition.

A $62$-year-old man is hospitalized due to a $4$-week history of low-grade fever, progressive fatigue, and generalized myalgias. He has a history of osteoarthritis and underwent a colonoscopy $2$ months ago for routine screening. His temperature is $38.3^\circ\text{C}$ ($100.9^\circ\text{F}$), blood pressure is $122/74\text{ mm Hg}$, and pulse is $92/\text{min}$. Physical examination reveals a grade $3/6$ holosystolic murmur heard best at the cardiac apex that radiates to the axilla. Splinter hemorrhages are noted on the fingernails of both hands. Laboratory studies show a leukocyte count of $14,000/\text{mm}^3$ and an erythrocyte sedimentation rate of $65\text{ mm/hr}$. A transesophageal echocardiogram demonstrates a $1.2\text{-cm}$ mobile vegetation on the mitral valve.

Three sets of blood cultures are drawn, and the patient is empirically started on intravenous vancomycin and ceftriaxone. Forty-eight hours later, all three blood culture sets grow *Enterococcus faecalis*. Antimicrobial susceptibility testing is reported as follows:

The patient's serum creatinine is $0.9\text{ mg/dL}$. He has no known drug allergies. Which of the following is the most appropriate next step in antimicrobial therapy?

A $34$-year-old female teacher comes to the primary care office complaining of severe throat pain and a fever that began abruptly yesterday. She notes difficulty swallowing but denies having a cough or rhinorrhea. Her temperature is $38.7^\circ\text{C}$ ($101.7^\circ\text{F}$), blood pressure is $118/76\text{ mmHg}$, and pulse is $92/\text{min}$. Physical examination reveals marked pharyngeal erythema, bilateral tonsillar exudates, and tender anterior cervical lymphadenopathy. A rapid antigen detection test is positive for Streptococcus pyogenes (Group A Streptococcus). The patient has no known drug allergies. Which of the following is the most appropriate next step in pharmacologic management?

Evaluate the following clinical presentations of immunocompromised patients with opportunistic infections. Match each clinical scenario with the most appropriate initial targeted pharmacotherapy.

A 55-year-old man with poorly controlled type 2 diabetes mellitus is evaluated in the hospital on day 4 of admission for a severe diabetic foot infection. He initially presented with a deep, purulent ulcer on the plantar aspect of his right foot surrounded by extensive cellulitis. On admission, empiric therapy was initiated with intravenous vancomycin and piperacillin-tazobactam, and he subsequently underwent surgical debridement of necrotic tissue. Today, his temperature is $37.1^\circ\text{C}$ ($98.8^\circ\text{F}$), blood pressure is $128/78\text{ mm Hg}$, and pulse is $78\text{/min}$. The wound appears clean with developing granulation tissue. Deep tissue cultures obtained during surgery yield heavy growth of Staphylococcus aureus. Antimicrobial susceptibility testing demonstrates resistance to penicillin and susceptibility to oxacillin, cefazolin, and vancomycin. Which of the following is the most appropriate next step in pharmacotherapy?

A $55$-year-old man is brought to the emergency department by his wife due to confusion, high fever, and a severe headache that started $12$ hours ago. His medical history is significant for a deceased-donor renal transplant $2$ years ago, for which he takes tacrolimus and mycophenolate mofetil. His temperature is $39.2^\circ\text{C}$ ($102.6^\circ\text{F}$), blood pressure is $105/65\text{ mm Hg}$, pulse is $115\text{/min}$, and respirations are $22\text{/min}$. On physical examination, the patient is lethargic but arousable. He has pronounced nuchal rigidity. Neurologic examination reveals left-sided pronator drift and a sluggish left pupillary reflex. Fundoscopy shows bilateral blurring of the optic discs. Arrange the following management steps in the most appropriate chronological order for this patient.

An emergency medical services team brings a 58-year-old male to the emergency department following a new-onset generalized tonic-clonic seizure. His wife reports that he had been complaining of a progressively worsening headache, severe neck stiffness, and subjective fevers for the past 48 hours. His temperature is 39.4°C (102.9°F), blood pressure is 112/68 mmHg, and pulse is 118/min. On physical examination, the patient is obtunded and grimaces upon neck flexion. Funduscopic examination shows no papilledema, but a detailed neurologic exam reveals a new right-sided pronator drift.

Arrange the following interventions in the most appropriate chronological sequence for this patient's management.

A 24-year-old woman, gravida 2 para 1, at 18 weeks gestation, presents to the clinic with a diffuse maculopapular rash that includes her palms and soles. She also reports generalized malaise and a low-grade fever over the past week. Her medical history is notable for a severe anaphylactic reaction (hypotension, wheezing, and angioedema) to amoxicillin prescribed for a respiratory infection two years ago. Laboratory evaluation reveals a rapid plasma reagin (RPR) titer of 1:64 and a reactive fluorescent treponemal antibody absorption (FTA-ABS) test. Arrange the following management steps in the most appropriate chronological order for this patient.

A physician is evaluating the antimicrobial regimen of a patient on the medical floor. The patient, a 58-year-old male, was admitted three days prior for management of severe shortness of breath and a productive cough. At the time of admission, imaging confirmed a left lower lobe consolidation, prompting the initiation of empiric intravenous ceftriaxone and azithromycin. Currently, the patient is clinically stable, breathing comfortably on ambient air, and tolerating his regular diet. He has not had a fever for over 24 hours. Laboratory data today reveals that the initial blood cultures are sterile. However, the admission sputum culture has finalized, demonstrating heavy growth of *Streptococcus pneumoniae*. Susceptibility profiling indicates the isolate is sensitive to penicillin, amoxicillin, levofloxacin, ceftriaxone, and vancomycin. Which of the following is the most appropriate next step in the pharmacologic management of this patient?

An otherwise healthy 45-year-old man presents to the primary care clinic for evaluation of an expanding red rash on his right lower extremity. He first noticed the redness 48 hours ago, and it has since become increasingly tender and warm. His medical history is notable only for recurrent tinea pedis, for which he sporadically uses an over-the-counter antifungal cream. His temperature is 37.2°C (99.0°F), pulse is 78/min, respirations are 14/min, and blood pressure is 126/82 mm Hg. Physical examination of the right lower leg demonstrates a poorly demarcated, erythematous, edematous, and warm plaque extending from the lateral ankle to the mid-calf. There are no fluctuant nodules, purulent exudates, or overlying ulcers. Bilateral pedal pulses are palpable and symmetric. Which of the following is the most appropriate empiric pharmacotherapy for this patient?

Match each clinical presentation of a common infectious disease with the most appropriate first-line pharmacotherapy.

A 67-year-old man is brought to the emergency department by his family due to a 1-day history of high fever, severe headache, and worsening confusion. His medical history is significant for hypertension and type 2 diabetes mellitus. His temperature is 39.4°C (102.9°F), blood pressure is 145/85 mm Hg, and pulse is 115/min. He is lethargic, mumbling incomprehensibly, and unable to follow complex commands. Neurologic examination shows a right-sided facial droop and right upper extremity weakness. Nuchal rigidity is present. Arrange the following steps in the most appropriate chronological sequence for the management of this patient.

A 45-year-old man is evaluated in the intensive care unit on day 8 of hospitalization. He was admitted after a motor vehicle collision that caused a severe traumatic brain injury and bilateral pulmonary contusions, requiring immediate intubation and mechanical ventilation. Over the past 24 hours, the nursing staff has noted an increase in the volume of thick, yellowish endotracheal secretions. The patient remains sedated. His temperature is $37.4^\circ\text{C}$ ($99.3^\circ\text{F}$), blood pressure is $128/78\text{ mmHg}$, heart rate is $86/\text{min}$, and respiratory rate is $16/\text{min}$. Physical examination reveals coarse rhonchi over both lung fields. Laboratory studies show a leukocyte count of $8,500/\text{mm}^3$. A portable chest radiograph demonstrates stable, resolving bilateral opacities with no new focal consolidations compared to imaging from three days prior. An endotracheal aspirate culture obtained yesterday grows $>10^5\text{ CFU/mL}$ of Pseudomonas aeruginosa. Which of the following is the most appropriate next step in the management of this patient?

Match each clinical vignette describing a systemic or opportunistic infection with the most appropriate primary therapeutic management.

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

Match each clinical scenario describing a high-risk infectious exposure with the most appropriate post-exposure prophylaxis (PEP) or management strategy.

During a shift in the emergency department, you evaluate a febrile patient who reports recent intravenous drug use. Physical examination reveals splinter hemorrhages, Janeway lesions, and a prominent holosystolic murmur at the apex radiating to the axilla. Suspecting acute infective endocarditis, the medical team prepares to initiate care. Arrange the following diagnostic and therapeutic steps in the most appropriate chronological order.

A 62-year-old man is evaluated in the hematology-oncology unit for persistent daily fevers. He was admitted 14 days ago to undergo induction chemotherapy for acute myeloid leukemia. Four days ago, he developed a fever of 38.9°C (102.0°F) when his absolute neutrophil count (ANC) was 200/mm³. After blood cultures were obtained, empiric intravenous cefepime was initiated. Today, his temperature is 38.8°C (101.8°F), blood pressure is 118/76 mmHg, pulse is 98/min, and respiratory rate is 18/min. His current ANC is 100/mm³. The initial blood cultures have shown no growth after 96 hours. The patient now reports the onset of mild, right-sided pleuritic chest pain. Physical examination reveals normal heart sounds and clear lung fields bilaterally. His tunneled central venous catheter site appears clean with no surrounding erythema or induration. A non-contrast chest CT demonstrates a 2.5-cm dense nodule in the right upper lobe surrounded by a distinct rim of ground-glass opacity. Serum galactomannan and beta-D-glucan assays are drawn and pending. Which of the following is the most appropriate next step in management?

A 54-year-old woman is brought to the emergency department by her daughter after experiencing a witnessed generalized tonic-clonic seizure. The patient has a history of severe systemic lupus erythematosus and is currently managed with chronic cyclophosphamide and high-dose prednisone. Her temperature is 39.3°C (102.7°F), blood pressure is 142/88 mm Hg, and heart rate is 114/min. She is postictal and difficult to arouse. Neurologic examination is limited by her somnolence but reveals profound nuchal rigidity. Arrange the following diagnostic and therapeutic steps in the most appropriate sequential order for the immediate management of this patient.