Infectious Diseases

Match each clinical presentation with the most appropriate antimicrobial stewardship intervention based on current clinical guidelines.

A $62$-year-old man comes to the emergency department complaining of severe, worsening lower back pain for the past $3$ weeks. The pain is constant, wakes him up at night, and is not relieved by rest or over-the-counter analgesics. He reports feeling warm at times but denies any leg weakness, numbness, or loss of bowel and bladder control. His medical history is significant for type 2 diabetes mellitus and end-stage renal disease, for which he receives hemodialysis via a right internal jugular venous catheter. Temperature is $37.9^\circ\text{C}$ ($100.2^\circ\text{F}$), blood pressure is $135/85 \text{ mm Hg}$, and pulse is $88/\text{min}$. Physical examination reveals exquisite tenderness to percussion over the L3 and L4 spinous processes. Neurologic examination of the lower extremities shows $5/5$ strength, normal sensation to pinprick and light touch, and $2+$ deep tendon reflexes symmetrically. Anal sphincter tone is normal. Laboratory studies show a leukocyte count of $9,500/\text{mm}^3$, an erythrocyte sedimentation rate of $88 \text{ mm/hr}$, and a C-reactive protein of $65 \text{ mg/L}$. Two sets of blood cultures are drawn. Magnetic resonance imaging of the lumbar spine reveals increased fluid signal in the L3-L4 intervertebral disc space with adjacent vertebral body marrow edema, consistent with pyogenic spondylodiscitis. There is no evidence of an epidural abscess or spinal cord compression. Which of the following is the most appropriate next step in the management of this patient?

During morning rounds on the general medical ward, a physician evaluates a $68$-year-old man undergoing treatment for severe community-acquired pneumonia. The patient was admitted $3$ days ago with acute respiratory distress, fever, and a dense right lower lobe consolidation on chest radiography. Due to a history of a recent hospitalization $6$ weeks prior, he was started on empiric intravenous vancomycin and piperacillin-tazobactam.

The patient's condition has markedly improved over the past $48$ hours. He is now breathing comfortably on room air, and his cough is producing only minimal clear sputum. His temperature is $37.2^\circ$ C ($99.0^\circ$ F), blood pressure is $130/82$ mmHg, pulse is $78$/min, and respirations are $16$/min. Blood cultures drawn at the time of admission are now positive for *Streptococcus pneumoniae* in two out of two bottles. Antimicrobial susceptibility testing demonstrates that the isolate is sensitive to penicillin, amoxicillin, ceftriaxone, and linezolid, but resistant to azithromycin.

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

A $58$-year-old man is brought to the emergency department by his wife due to severe headache, high fever, and confusion that started $12$ hours ago. On examination, his temperature is $39.4^\circ\text{C}$ ($102.9^\circ\text{F}$), blood pressure is $110/70\text{ mmHg}$, and heart rate is $112\text{/min}$. The patient is lethargic and oriented only to his name. Nuchal rigidity is present. There are no focal neurologic deficits. The physician suspects acute bacterial meningitis.

Arrange the following steps in the most appropriate chronological order for the management of this patient.

A 68-year-old man is brought to the emergency department by his family due to a 24-hour history of high fever, severe generalized headache, and progressive confusion. His medical history is significant for type 2 diabetes mellitus and hypertension. On presentation, his temperature is $39.4^\circ\text{C}$ ($102.9^\circ\text{F}$), blood pressure is $110/70\text{ mmHg}$, heart rate is $115/\text{min}$, and respiratory rate is $22/\text{min}$. The patient is somnolent and oriented only to person. Neurologic examination reveals marked nuchal rigidity. Fundoscopic examination demonstrates bilateral blurring of the optic disc margins.

Arrange the following steps in the most appropriate chronological order for managing this patient.

A 62-year-old woman is evaluated on the third day of hospitalization for a central line-associated bloodstream infection. She has been receiving total parenteral nutrition through a central venous catheter for short bowel syndrome. Three days ago, she experienced the sudden onset of rigors, a temperature of 39.2°C (102.6°F), and a blood pressure of 90/60 mmHg. Blood cultures drawn from both the central catheter and a peripheral vein revealed Gram-positive cocci in clusters. The catheter was promptly removed, and empiric intravenous vancomycin and cefepime were started. Today, she feels well and is afebrile with normal hemodynamics. Final blood culture results confirm the presence of Staphylococcus aureus in all bottles. Susceptibility testing indicates the isolate is resistant to penicillin but susceptible to oxacillin, cefazolin, and vancomycin. Which of the following is the most appropriate modification to her antimicrobial therapy?

An inpatient infectious disease consultation is requested for a $54$-year-old man who has been hospitalized for the past $3$ weeks following an extensive bowel resection for acute mesenteric ischemia. Due to short bowel syndrome, he has been dependent on total parenteral nutrition administered via a right upper extremity peripherally inserted central catheter (PICC). Yesterday, the patient experienced a sudden onset of rigors and a temperature spike to $39.1^\circ\text{C}$ ($102.4^\circ\text{F}$). His blood pressure dropped to $105/65$ mm Hg with a pulse of $110$/min. Examination of the PICC insertion site revealed focal erythema and tenderness. The catheter was promptly removed, and empiric intravenous vancomycin and piperacillin-tazobactam were initiated. Today, the patient is afebrile and hemodynamically stable. Preliminary blood cultures from both the PICC tip and a peripheral draw are positive for *Staphylococcus aureus* in $4$ out of $4$ bottles. Final susceptibility results show the isolate is resistant to penicillin but susceptible to oxacillin, cefazolin, clindamycin, and vancomycin. Which of the following is the most appropriate next step in pharmacotherapy?

Match the following specific clinical presentations of infectious diseases with their most appropriate first-line targeted antimicrobial therapy.

Match each clinical presentation of an opportunistic infection in a patient with advanced HIV to the most appropriate initial targeted pharmacotherapy.

Following a transfer from a long-term care facility, an 82-year-old female patient is evaluated in the hospital for a two-day history of progressive somnolence. Her medical history is significant for advanced Alzheimer dementia and chronic urinary retention requiring an indwelling urethral catheter. Upon presentation, her blood pressure is $112/64\text{ mmHg}$, heart rate is $96/\text{min}$, and temperature is $36.9^\circ\text{C}$ ($98.4^\circ\text{F}$). Physical examination reveals dry oral mucosa, diminished skin turgor, and no costovertebral angle tenderness. The patient is lethargic but arouses to voice. Laboratory evaluation reveals a serum sodium concentration of $159\text{ mEq/L}$ and a blood urea nitrogen level of $45\text{ mg/dL}$. A urinalysis demonstrates cloudy, malodorous urine with positive leukocyte esterase, positive nitrites, and $45\text{ WBCs/hpf}$. A urine culture is submitted, and she is started on intravenous fluid resuscitation.

By the third day of hospitalization, her serum sodium has corrected to $142\text{ mEq/L}$, and her mental status has returned to her baseline of being pleasantly confused but conversational. She remains hemodynamically stable and afebrile. The admission urine culture now reports $>10^5\text{ CFU/mL}$ of *Escherichia coli* that is susceptible to all tested antimicrobial agents. Which of the following is the most appropriate next step in the management of this patient's urinary findings?

A 64-year-old man with a 15-year history of type 2 diabetes mellitus is evaluated in the outpatient clinic for a chronic ulcer on the plantar surface of his right great toe. Over the past 3 days, he has noted new-onset redness and mild pain surrounding the ulcer. He has not had fever, chills, or other systemic symptoms. He has no recent hospitalizations and has not received any antibiotics in the past year. Vital signs are temperature 37.0°C (98.6°F), blood pressure 135/85 mm Hg, heart rate 78/min, and respirations 14/min. Physical examination reveals a 1.5-cm, shallow ulcer on the plantar aspect of the right great toe. There is a 1-cm rim of blanching erythema surrounding the ulcer margins. There is no purulent drainage, fluctuance, or crepitus. The ulcer base does not probe to bone, and pedal pulses are palpable bilaterally. A superficial swab culture of the ulcer base obtained by a visiting home nurse 3 days ago shows heavy growth of methicillin-susceptible Staphylococcus aureus (MSSA) and Pseudomonas aeruginosa. Which of the following is the most appropriate next step in the pharmacologic management of this patient?

A 45-year-old man who recently emigrated from an area highly endemic for tuberculosis presents to the emergency department with a 4-week history of productive cough, blood-tinged sputum, drenching night sweats, and unintentional weight loss. Vital signs show a temperature of 38.3°C (100.9°F). A chest radiograph reveals a large cavitary lesion in the apical segment of the right upper lobe. Arrange the following management steps in the most appropriate chronological sequence for this patient.

A $74$-year-old woman is evaluated in the preoperative clinic $5$ days before a scheduled right total knee arthroplasty. She has a history of severe osteoarthritis and chronic urge incontinence, which has been stable on a scheduled voiding regimen. The patient reports no new symptoms and specifically denies dysuria, urinary frequency, suprapubic discomfort, or flank pain. Her current medications include acetaminophen and cholecalciferol. Vital signs are within normal limits, including a temperature of $37.0^\circ\text{C}$ ($98.6^\circ\text{F}$). Physical examination shows severe right knee crepitus and limited range of motion. There is no costovertebral angle or suprapubic tenderness. Preoperative laboratory results are as follows:

Leukocyte count: $7,800/\mu\text{L}$
Hemoglobin: $12.4$ g/dL
Platelets: $210,000/\mu\text{L}$

Urinalysis:
Color: Yellow
Appearance: Cloudy
Specific gravity: $1.018$
pH: $7.5$
Leukocyte esterase: Positive
Nitrites: Positive
WBC: $30$/hpf
Bacteria: Many

A urine culture grows $>10^5$ CFU/mL of *Proteus mirabilis* that is susceptible to cefazolin, ceftriaxone, and ciprofloxacin. Which of the following is the most appropriate management of this patient's urinary findings prior to surgery?

Match each clinical exposure scenario with the most appropriate targeted post-exposure management or prophylaxis protocol.

A $68$-year-old man is evaluated in the hospital for a new-onset fever. He was admitted $5$ days ago for an acute exacerbation of chronic obstructive pulmonary disease, which has significantly improved with intravenous corticosteroids and bronchodilators. A Foley catheter was placed on admission for strict fluid monitoring but was removed $48$ hours later. Yesterday, he developed a fever of $38.6^\circ\text{C}$ ($101.5^\circ\text{F}$), dysuria, and suprapubic tenderness. Urinalysis revealed $50$ leukocytes per high-power field and positive leukocyte esterase. He was empirically started on intravenous piperacillin-tazobactam and vancomycin. Today, the patient's fever has resolved, his urinary symptoms are improving, and he is tolerating an oral diet. Blood cultures drawn concurrently have no growth to date. Cardiac examination reveals a regular rate and rhythm with no murmurs. Urine culture from yesterday grows $>100,000$ CFU/mL of *Enterococcus faecalis*. Susceptibility testing demonstrates that the isolate is susceptible to ampicillin, vancomycin, and linezolid.

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

A 42-year-old man with a history of poorly controlled HIV infection presents to the emergency department with a 2-day history of worsening headache, severe photophobia, and confusion. On presentation, his temperature is 39.4°C (102.9°F), blood pressure is 115/75 mm Hg, pulse is 118/min, and respirations are 18/min. Physical examination reveals marked nuchal rigidity. He is oriented only to his name. Funduscopic examination shows blurring of the optic disc margins bilaterally.

Arrange the following steps in the most appropriate chronological order for the initial management of this patient.

An otherwise healthy 30-year-old construction worker presents to an urgent care center reporting localized pain and swelling on his left thigh that began four days ago. He recalls a minor abrasion at the site but denies fevers, chills, or systemic symptoms. His vital signs are within normal limits. Physical examination demonstrates a 3.5-cm, exquisitely tender, erythematous, and fluctuant nodule on the anterolateral aspect of the left thigh. There is spontaneous drainage of a small amount of purulent fluid. No surrounding induration extending beyond the immediate area, crepitus, or regional lymphadenopathy is appreciated. Which of the following is the most appropriate management for this patient?

A 71-year-old woman is evaluated in the intensive care unit for progressive abdominal distension and altered mental status. She was admitted four days ago for severe *Clostridioides difficile* infection and was appropriately started on oral vancomycin. Today, she is lethargic and confused. Her temperature is $38.9^\circ\text{C}$ ($102.0^\circ\text{F}$), blood pressure is $84/52\text{ mm Hg}$, pulse is $124/\text{min}$, and respiratory rate is $22/\text{min}$. Physical examination reveals a markedly distended, tympanitic abdomen with diffuse tenderness. Bowel sounds are absent. She has had no bowel movements in the past $24$ hours. Laboratory studies show a leukocyte count of $32,000/\text{mm}^3$ and a serum creatinine level of $2.3\text{ mg/dL}$. An abdominal radiograph demonstrates colonic dilation measuring $9\text{ cm}$ in the transverse colon, with loss of haustral markings and no free intraperitoneal air. Which of the following is the most appropriate next step in the management of this patient's infection?

Match each clinical presentation of an opportunistic infection in an immunocompromised patient with the most appropriate first-line targeted pharmacotherapy.

A 58-year-old man is evaluated in the hospital on the third day of admission for a catheter-related bloodstream infection. He initially presented to the emergency department with fever, chills, and hypotension during his outpatient hemodialysis session. At admission, blood cultures were drawn, his tunneled hemodialysis catheter was removed, and he was started on empiric intravenous vancomycin and cefepime. His past medical history is notable for end-stage renal disease, hypertension, and type 2 diabetes mellitus. His medical record indicates an allergy to amoxicillin, which caused a diffuse, non-pruritic maculopapular rash 15 years ago. Today, the patient is afebrile and hemodynamically stable. The blood cultures drawn at admission are growing *Staphylococcus aureus*.

Susceptibility testing results are as follows:

Which of the following is the most appropriate next step in antibiotic management?