Infectious Diseases

Match each clinical exposure scenario with the most appropriate pharmacological prophylaxis or empiric antimicrobial regimen.

A 58-year-old man is evaluated in the hospital on the third day of his admission for acute pyelonephritis. He originally presented with right flank pain, chills, and dysuria. At the time of admission, his temperature was $39.2^\circ \text{C}$ ($102.6^\circ \text{F}$), heart rate was $110/\text{min}$, and blood pressure was $105/65 \text{ mmHg}$. He was empirically started on intravenous piperacillin-tazobactam.

Today, the patient reports significant improvement in his symptoms. His flank pain has resolved, and he has been afebrile for the past 24 hours. Current vital signs are temperature $37.1^\circ \text{C}$ ($98.8^\circ \text{F}$), heart rate $82/\text{min}$, and blood pressure $122/78 \text{ mmHg}$. He is tolerating a regular diet.

Blood cultures drawn on admission show no growth. Urine cultures from admission grow $>100,000 \text{ CFU/mL}$ of *Escherichia coli*. Antimicrobial susceptibility testing results are as follows:

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

A 62-year-old male is brought to the emergency department by his family due to a severe headache, confusion, and a high fever that began 18 hours ago. His temperature is $39.1^\circ\text{C}$ ($102.4^\circ\text{F}$), blood pressure is $138/82\text{ mmHg}$, heart rate is $112\text{/min}$, and respiratory rate is $20\text{/min}$. Physical examination reveals nuchal rigidity and a positive Brudzinski sign. Neurologic examination is notable for a left-sided hemiparesis and bilateral papilledema on fundoscopy. The physician suspects acute bacterial meningitis and prepares to manage the patient.

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

A 57-year-old woman is admitted to the hospital due to a two-day history of diffuse abdominal pain, generalized weakness, and subjective fevers. Her past medical history is significant for alcohol-associated cirrhosis and esophageal varices. On physical examination, her temperature is 38.3°C (100.9°F), blood pressure is 105/65 mmHg, and heart rate is 102/min. Her abdomen is distended, tense, and diffusely tender to palpation, with shifting dullness present. Due to initial hypotension and concern for sepsis, she was empirically started on broad-spectrum coverage with intravenous piperacillin-tazobactam and daptomycin in the emergency department. A diagnostic paracentesis was also promptly performed, yielding cloudy fluid with an absolute neutrophil count of $750/mm^3$. It is now hospital day 3. The patient's fever has resolved and her abdominal pain has significantly improved. The ascitic fluid culture from admission now grows *Klebsiella pneumoniae*. Antimicrobial susceptibility testing indicates that the isolate is sensitive to ceftriaxone, cefepime, piperacillin-tazobactam, and meropenem. Which of the following is the most appropriate management of this patient's pharmacotherapy?

A 68-year-old man is evaluated on hospital day 3 for management of community-acquired pneumonia. He was admitted with a 3-day history of productive cough, fever, and shortness of breath. On admission, chest radiography revealed a left lower lobe infiltrate. He was started on empiric intravenous ceftriaxone and intravenous azithromycin. Today, his cough and shortness of breath have significantly improved. He is tolerating a regular diet well. His temperature is $37.1^{\circ}\text{C}$ ($98.8^{\circ}\text{F}$), blood pressure is $128/82\text{ mm Hg}$, pulse is $78/\text{min}$, and respiratory rate is $16/\text{min}$. Oxygen saturation is $96\%$ on ambient air. A sputum culture obtained on admission grew *Streptococcus pneumoniae*. Antimicrobial susceptibility testing demonstrates that the isolate is susceptible to penicillin, amoxicillin, ceftriaxone, and levofloxacin, but resistant to azithromycin. Which of the following is the most appropriate next step in antimicrobial therapy?

Match each clinical presentation of a localized skin and soft tissue infection with the most appropriate empiric oral antimicrobial therapy.

A 29-year-old male with a history of intravenous heroin use is brought to the emergency department with a 3-day history of high fevers, severe chills, and progressive shortness of breath. His temperature is $39.2^\circ\text{C}$ ($102.6^\circ\text{F}$), blood pressure is $90/55\text{ mm Hg}$, pulse is $118/\text{min}$, and respiratory rate is $22/\text{min}$. Physical examination reveals a loud holosystolic murmur best heard at the left lower sternal border that increases in intensity with inspiration. Nontender, erythematous macules are noted on the palms and soles. He appears toxic and lethargic. The physician suspects acute right-sided infective endocarditis and initiates the management protocol. Arrange the following management steps in the most appropriate chronological sequence.

A 78-year-old female resident of a skilled nursing facility is brought to the outpatient clinic by her daughter for a routine health maintenance visit. The daughter expresses concern because the nursing staff recently noted that the patient's urine has become malodorous and cloudy over the past three days. The patient has a medical history significant for type 2 diabetes mellitus, essential hypertension, and osteoarthritis of the knees. When asked, the patient denies any dysuria, increased urinary frequency, or urgency. She also reports no suprapubic discomfort, flank pain, fever, or chills. Her baseline mental status is alert and oriented to person, place, and time, and the daughter confirms there has been no recent confusion, agitation, or behavioral changes. Vital signs include a temperature of 37.0°C (98.6°F), blood pressure of 132/82 mmHg, heart rate of 76/min, and respiratory rate of 14/min. Physical examination reveals a non-tender abdomen, absent costovertebral angle tenderness, and normal bowel sounds. A point-of-care urinalysis demonstrates positive leukocyte esterase, positive nitrites, and 15-20 white blood cells per high-power field, along with numerous bacteria. Which of the following is the most appropriate next step in management?

A 62-year-old man is evaluated in the intensive care unit for ongoing management of ventilator-associated pneumonia. He was intubated 6 days ago for severe acute respiratory distress syndrome. Three days ago, he developed a new fever, increased purulent endotracheal secretions, and worsening oxygenation. At that time, empiric intravenous vancomycin, cefepime, and ciprofloxacin were initiated. Today, his temperature is 37.2°C (99.0°F), leukocyte count has decreased from 16,000/mm³ to 9,500/mm³, and his oxygen requirements have significantly improved. Blood cultures have shown no growth. Endotracheal aspirate culture from three days ago grows Pseudomonas aeruginosa. Susceptibility testing shows the isolate is susceptible to cefepime, piperacillin-tazobactam, and ciprofloxacin. A methicillin-resistant Staphylococcus aureus (MRSA) nasal polymerase chain reaction screen performed on admission was negative, and no Gram-positive organisms are seen on the respiratory culture Gram stain. Which of the following is the most appropriate next step in antibiotic management?

A 52-year-old man is brought to the emergency department by his wife due to a 24-hour history of severe generalized headache, high fever, and progressive confusion. His temperature is 39.4°C (102.9°F), blood pressure is 142/88 mmHg, and heart rate is 112/min. On physical examination, he is lethargic and oriented only to person. Neck flexion produces involuntary hip and knee flexion. Ophthalmoscopic examination reveals bilateral optic disc swelling with blurred margins. Arrange the following management steps in the most appropriate chronological order for this patient.

During morning rounds on the inpatient hematology-oncology unit, a 42-year-old woman is evaluated for a new-onset fever. She was admitted seven days ago for induction chemotherapy to treat acute myeloid leukemia. Her temperature is 38.9°C (102.0°F), blood pressure is 118/74 mm Hg, pulse is 92/min, and respiratory rate is 16/min. The patient reports feeling fatigued but denies cough, dysuria, abdominal pain, or skin changes. Physical examination reveals a clean peripherally inserted central catheter site with no surrounding erythema, warmth, or induration. The lungs are clear to auscultation. Laboratory studies show a hemoglobin of 8.2 g/dL, platelet count of 45,000/mm³, and an absolute neutrophil count of 300/mm³. Renal and hepatic function panels are within normal limits. Blood and urine cultures have been obtained. Which of the following is the most appropriate initial pharmacotherapy for this patient?

Match each infectious disease clinical scenario with the most appropriate targeted antimicrobial therapy or post-exposure prophylaxis regimen.

A 45-year-old man presents to the emergency department with a 4-week history of productive cough, hemoptysis, drenching night sweats, and a $6\text{-kg}$ ($13\text{-lb}$) weight loss. He recently emigrated from a region highly endemic for tuberculosis. His temperature is $38.3^\circ\text{C}$ ($100.9^\circ\text{F}$), blood pressure is $120/78\text{ mm Hg}$, and pulse is $92/\text{min}$. A chest radiograph reveals a $3\text{-cm}$ cavitary lesion in the right upper lobe. Arrange the following management steps in the most appropriate chronological sequence.

A 71-year-old woman who resides in a skilled nursing facility is currently receiving care in the intensive care unit for septic shock. She initially presented 48 hours ago with a temperature of 39.2°C (102.6°F), lethargy, and severe hypotension. A chronically encrusted indwelling urinary catheter was identified as the suspected source and immediately removed. Due to her frequent healthcare exposure and risk for multidrug-resistant organisms, empiric antimicrobial therapy was initiated with meropenem and linezolid. She has improved significantly over the past two days, and vasopressor support has been successfully discontinued. Current vital signs are temperature 37.1°C (98.8°F), blood pressure 122/78 mm Hg, pulse 84/min, and respirations 16/min. Finalized results from both blood and urine cultures isolate Proteus mirabilis. Susceptibility testing reveals the organism is resistant to tetracycline but fully susceptible to ampicillin, ceftriaxone, cefepime, piperacillin-tazobactam, and meropenem. Which of the following is the most appropriate pharmacological intervention at this time?

Select the most appropriate first-line antimicrobial therapy for each of the following patient presentations.

A $68$-year-old man is evaluated in the hospital on the $3$ rd day of admission for sepsis secondary to a complicated urinary tract infection. He initially presented to the emergency department with fever, severe chills, and left-sided flank pain. His medical history includes benign prostatic hyperplasia and type 2 diabetes mellitus. On admission, his blood pressure was $88/56$ mm Hg and his heart rate was $112$/min. He received aggressive intravenous fluid resuscitation and was started on empiric intravenous vancomycin and cefepime.

Currently, the patient is clinically stable. His temperature is $37.1^\circ\text{C}$ ($98.8^\circ\text{F}$), blood pressure is $126/82$ mm Hg, and pulse is $78$/min. He reports that his flank pain has significantly improved.

Blood and urine cultures obtained on admission both grow $>100,000$ CFU/mL of *Enterococcus faecalis*. Antimicrobial susceptibility testing results are as follows:

Ampicillin: Susceptible
Vancomycin: Susceptible
Linezolid: Susceptible
Daptomycin: Susceptible
Ciprofloxacin: Resistant

Which of the following is the most appropriate next step in the antimicrobial management of this patient?

A 55-year-old male is brought to the emergency department by his partner due to severe headache, fever, and progressive confusion over the past 24 hours. He has a known history of HIV infection and his most recent CD4 count was 150/mm³. Vital signs show a temperature of 39.0°C (102.2°F), blood pressure of 110/70 mm Hg, and heart rate of 112/min. On physical examination, marked nuchal rigidity is present. Neurological evaluation reveals a sluggishly reactive right pupil and a new mild left-sided hemiparesis. A diagnosis of bacterial meningitis is strongly suspected.

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

A 76-year-old woman is evaluated in the clinic prior to an elective right total knee arthroplasty scheduled for the following week. She has a history of osteoarthritis and well-controlled essential hypertension. She reports no new symptoms and specifically denies dysuria, urinary frequency, urgency, suprapubic pain, fever, or chills. Her temperature is $37.1^\circ\text{C}$ ($98.8^\circ\text{F}$), blood pressure is $128/78\text{ mm Hg}$, and pulse is $76/\text{min}$. Physical examination of the abdomen and costovertebral angles is unremarkable. As part of her preoperative evaluation, a urinalysis is obtained which shows $15$ white blood cells/hpf and is positive for leukocyte esterase and nitrites. A subsequent urine culture grows $>10^5\text{ CFU/mL}$ of Escherichia coli that is susceptible to ceftriaxone, ciprofloxacin, trimethoprim-sulfamethoxazole, and nitrofurantoin. Which of the following is the most appropriate management regarding these laboratory findings?

Match each patient presentation describing a suspected tick-borne illness with the most appropriate targeted antimicrobial therapy.

A $54$-year-old man is evaluated in the hospital on his third day of admission for community-acquired pneumonia. He was initially started on empiric therapy with intravenous ceftriaxone and oral azithromycin. His cough and shortness of breath have significantly improved, and he has been afebrile for the past $24$ hours. He is currently tolerating a regular diet. Sputum cultures collected on admission grew *Streptococcus pneumoniae*. Susceptibility testing reveals that the isolate is susceptible to penicillin, amoxicillin, ceftriaxone, levofloxacin, and vancomycin, and resistant to azithromycin. He has no known drug allergies. Vital signs are temperature $37.0^\circ\text{C}$ ($98.6^\circ\text{F}$), pulse $76/\text{min}$, respirations $14/\text{min}$, and blood pressure $124/78\text{ mmHg}$. Pulse oximetry is $97\%$ on room air. The patient is being prepared for discharge. Which of the following is the most appropriate antimicrobial regimen to prescribe for this patient upon discharge?