Infectious Diseases

A 68-year-old woman is brought to the emergency department by her family due to a 24-hour history of fever, severe headache, and progressively worsening confusion. She has a medical history of rheumatoid arthritis and is currently on chronic immunosuppressive therapy with methotrexate and prednisone. On physical examination, her temperature is 39.2°C (102.6°F), blood pressure is 105/65 mmHg, and heart rate is 118/min. She is lethargic, oriented only to her own name, and exhibits marked nuchal rigidity. There are no clear focal neurologic deficits, but a thorough neurologic examination is limited by her altered mental status. Based on her clinical presentation and risk factors, arrange the following management steps in the most appropriate chronological sequence.

A 78-year-old woman is brought to the primary care clinic for a routine wellness visit. Her daughter reports that the patient has been eating well, sleeping normally, and participating in her usual daily activities. Her medical history is notable for hypertension and mild Alzheimer dementia. The patient's cognitive function is at her usual baseline, and she has not experienced any recent falls, confusion, or behavioral changes. She denies dysuria, increased urinary frequency, or lower abdominal pain. Vital signs, including a temperature of $37.1^{\circ}\mathrm{C}$ ($98.8^{\circ}\mathrm{F}$), are within normal limits. A urinalysis is obtained as part of a general screening panel, which returns positive for leukocyte esterase and nitrites. A subsequent urine culture grows $>10^5$ colony-forming units/mL of Escherichia coli. Which of the following is the most appropriate next step in management?

A 24-year-old woman presents to the outpatient clinic with a 2-day history of painful urination and increased urinary frequency. She reports no fever, chills, nausea, vomiting, vaginal discharge, or back pain. She is otherwise healthy, has no known drug allergies, and takes no medications. Vital signs are within normal limits. Physical examination reveals mild suprapubic tenderness but is negative for costovertebral angle tenderness. A urine dipstick test is positive for leukocyte esterase and nitrites. Which of the following is the most appropriate empiric pharmacotherapy for this patient?

Match each of the following hospital-acquired pathogen profiles with the most appropriate targeted antimicrobial therapy. Assume the patient has no reported drug allergies and normal renal function.

A 42-year-old man presents to the emergency department with a 6-week history of chronic cough productive of blood-tinged sputum, drenching night sweats, fatigue, and an unintentional 6-kg (13-lb) weight loss. He recently immigrated to the United States from a country with a high incidence of tuberculosis. His temperature is 38.2°C (100.8°F), blood pressure is 118/76 mm Hg, pulse is 98/min, and respirations are 18/min. A portable chest radiograph performed in the triage area reveals a 3-cm 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 45-year-old man is hospitalized for the treatment of severe cellulitis of the right lower extremity. On admission, blood cultures were drawn, and he was started on empiric intravenous vancomycin and ceftriaxone. On hospital day 3, the patient is afebrile, and the erythema has significantly decreased. The blood cultures return positive for Staphylococcus aureus. Susceptibility testing shows the organism is resistant to penicillin but susceptible to oxacillin, cefazolin, and vancomycin. Which of the following is the most appropriate next step in antibiotic therapy?

A 54-year-old man is hospitalized for a 3-day history of high fever, severe back pain, and chills. He has a history of type 2 diabetes mellitus and intravenous drug use. Temperature is 39.2°C (102.6°F), blood pressure is 110/70 mm Hg, and pulse is 112/min. Physical examination reveals point tenderness over the L3-L4 vertebrae and a new soft systolic murmur heard at the left lower sternal border. Blood cultures are drawn, and he is started empirically on intravenous vancomycin and piperacillin-tazobactam. Magnetic resonance imaging of the spine reveals L3-L4 osteomyelitis with an associated anterior epidural abscess. On day 3 of hospitalization, blood cultures grow Staphylococcus aureus. Susceptibility testing shows the organism is resistant to penicillin and susceptible to oxacillin, cefazolin, and vancomycin. Which of the following is the most appropriate next step in the patient's pharmacotherapy?

Match each common respiratory pathogen causing community-acquired pneumonia with its classic clinical presentation, laboratory finding, or associated risk factor.

An 82-year-old woman with a history of vascular dementia is evaluated on the surgical ward for acute confusion. She underwent a right total hip arthroplasty $24$ hours ago. Over the past $6$ hours, she has become highly agitated, disoriented, and reports seeing insects on the ceiling. She is currently receiving intravenous morphine as needed for postoperative pain. Her temperature is $37.1^\circ\text{C}$ ($98.8^\circ\text{F}$), blood pressure is $132/78$ mmHg, pulse is $82$/min, and respirations are $14$/min. Physical examination reveals no suprapubic or costovertebral angle tenderness. The surgical incision is clean and intact. Laboratory studies show a leukocyte count of $8,400/\text{mm}^3$. A routine urinalysis obtained in the emergency department prior to surgery showed $25$ leukocytes/hpf, positive leukocyte esterase, and positive nitrites. The admission urine culture now grows $>10^5 \text{ CFU/mL}$ of *Escherichia coli* susceptible to ceftriaxone, ciprofloxacin, and trimethoprim-sulfamethoxazole. Which of the following is the most appropriate management of this patient's bacteriuria?

A 66-year-old man is brought to the emergency department by his family due to a severe, generalized headache, high fever, and progressive confusion over the past 24 hours. His medical history is significant for multiple myeloma, for which he is currently receiving maintenance chemotherapy. On arrival, his temperature is 39.4°C (102.9°F), blood pressure is 88/54 mmHg, pulse is 122/min, and respirations are 22/min. Physical examination reveals prominent nuchal rigidity and a new-onset right pronator drift. He is oriented only to his name. Arrange the following management steps in the most appropriate chronological order for this patient.

Match each clinical scenario describing a recent infectious exposure or early clinical presentation with the most appropriate targeted empiric therapy or post-exposure prophylaxis.

During multidisciplinary rounds in the intensive care unit, a clinical pharmacist raises a concern regarding a patient being treated for infective endocarditis. The patient was admitted 8 days ago after presenting with a one-month history of fatigue, low-grade fevers, and painful, erythematous nodules on the distal fingers. Initial blood cultures grew *Enterococcus faecalis* that was widely susceptible, including to ampicillin, vancomycin, and high-level gentamicin. Echocardiography confirmed a 1.2-cm vegetation on the native mitral valve. The patient was promptly started on intravenous ampicillin and scheduled doses of intravenous gentamicin. Today, the patient is afebrile and hemodynamically stable. However, routine laboratory studies reveal a serum creatinine level of 2.6 mg/dL, an increase from 0.8 mg/dL on admission. Urinalysis demonstrates muddy brown casts. Which of the following is the most appropriate modification to this patient's pharmacotherapy?

A 19-year-old man presents to the university health clinic with a 2-day history of fever, severe sore throat, and painful swallowing. He reports no cough, rhinorrhea, or hoarseness. His temperature is 38.6°C (101.5°F), blood pressure is 118/76 mm Hg, and pulse is 98/min. Physical examination reveals enlarged, erythematous tonsils with whitish exudates and bilateral tender anterior cervical lymphadenopathy. A rapid antigen detection test for Group A *Streptococcus* is positive. The patient has no known drug allergies. Which of the following is the most appropriate antibiotic regimen?

A 55-year-old woman is evaluated in the hospital on day 2 of admission for uncomplicated community-acquired pneumonia. She was initially started on intravenous ceftriaxone and azithromycin. Over the past 48 hours, her temperature has normalized from an admission peak of 38.9°C (102.0°F) to 37.2°C (99.0°F), and her respiratory effort has markedly improved. Two sets of peripheral blood cultures (four bottles total) were obtained in the emergency department prior to antibiotic administration. Today, the laboratory reports that one aerobic bottle from the first set is growing Staphylococcus epidermidis. The other three bottles exhibit no growth after 48 hours of incubation. The patient has no indwelling vascular catheters or prosthetic devices. Upon receiving the culture report, the cross-covering physician immediately adds intravenous vancomycin to the patient's regimen. Which of the following is the most appropriate next step in the management of this patient's pharmacotherapy?

A 68-year-old man is admitted to the hospital due to a 4-week history of progressively worsening lower back pain. The pain is localized to the lower lumbar area, is dull and constant, and frequently awakens him from sleep. It is not relieved by rest or over-the-counter ibuprofen. He has a history of type 2 diabetes mellitus and benign prostatic hyperplasia. Six weeks ago, he underwent a transurethral resection of the prostate. His temperature is $38.2^\circ\text{C}$ ($100.8^\circ\text{F}$), blood pressure is $135/85\text{ mmHg}$, pulse is $88/\text{min}$, and respiratory rate is $14/\text{min}$. Physical examination reveals exquisite point tenderness over the L4 and L5 spinous processes. Neurological examination of the lower extremities shows 5/5 motor strength, normal sensation, and 2+ symmetric deep tendon reflexes. Anal sphincter tone is normal. Laboratory studies show a leukocyte count of $11,500/\text{mm}^3$, an erythrocyte sedimentation rate of $85\text{ mm/h}$, and a C-reactive protein level of $72\text{ mg/L}$. Magnetic resonance imaging of the lumbar spine reveals fluid in the L4-L5 intervertebral disc space with T2 hyperintensity and gadolinium enhancement of the adjacent vertebral endplates. Blood cultures are drawn on admission. Forty-eight hours later, the blood cultures show no growth, and the patient's clinical status remains unchanged. Which of the following is the most appropriate next step in management?

A 47-year-old woman is evaluated on her third day of hospitalization for community-acquired pneumonia. At the time of admission, empiric therapy with intravenous ceftriaxone and oral azithromycin was initiated. She currently feels much better, and her cough has significantly decreased. Vital signs are temperature 37.0°C (98.6°F), blood pressure 124/76 mm Hg, pulse 78/min, and respirations 14/min. Oxygen saturation is 98% on room air. Sputum culture collected prior to antibiotic administration now grows Streptococcus pneumoniae. Susceptibility testing indicates the isolate is highly susceptible to penicillin, ceftriaxone, macrolides, and respiratory fluoroquinolones. The patient is tolerating a regular diet and has adequate gastrointestinal absorption. Which of the following is the most appropriate next step in pharmacotherapy?

A 62-year-old woman is evaluated in the hospital on day 4 of admission. She initially presented to the emergency department with a 2-day history of high fever, chills, and severe right-sided back pain. On admission, her temperature was $39.2^\circ\text{C}$ ($102.6^\circ\text{F}$), blood pressure was $110/70\text{ mmHg}$, and heart rate was $115\text{/min}$. Physical examination revealed pronounced right costovertebral angle tenderness. Laboratory studies showed a leukocyte count of $16,500\text{/mm}^3$. She was started on empiric intravenous ceftriaxone.

On hospital day 2, her fever persisted. Urine culture grew $>10^5\text{ CFU/mL}$ of *Escherichia coli*. The isolate was identified as an extended-spectrum beta-lactamase (ESBL) producer. Antimicrobial susceptibility testing showed the following:

- Ceftriaxone: Resistant
- Cefepime: Resistant
- Piperacillin-tazobactam: Resistant
- Meropenem: Susceptible
- Ertapenem: Susceptible
- Ciprofloxacin: Susceptible
- Nitrofurantoin: Susceptible
- Fosfomycin: Susceptible

Her regimen was subsequently changed to intravenous ertapenem. Today (hospital day 4), the patient is afebrile, her flank pain has resolved, and her leukocyte count has normalized to $8,500\text{/mm}^3$. She is tolerating a regular diet and is eager to be discharged.

Which of the following is the most appropriate antimicrobial regimen for discharge?

An otherwise healthy 24-year-old university student presents to the student health center reporting discomfort when urinating. Vital signs show a temperature of 37.0°C (98.6°F), blood pressure of 118/76 mmHg, and a heart rate of 78/min. She reports that she has been urinating more frequently than usual over the past 48 hours. She has not experienced any fevers, chills, nausea, back pain, or abnormal vaginal discharge. An abdominal examination demonstrates mild tenderness located just above the pubic symphysis, but there is no pain elicited upon percussion of the costovertebral angles bilaterally. A clean-catch urine specimen is analyzed and demonstrates positive results for both leukocyte esterase and nitrites. Which of the following is the most appropriate empiric pharmacotherapy for this patient?

A 24-year-old man comes to the clinic with fever, myalgias, and a rash 14 days after high-risk sexual exposure. Acute human immunodeficiency virus (HIV) infection is suspected. Arrange the following steps of the HIV diagnostic and initial management algorithm in the correct chronological sequence, assuming each diagnostic test yields a result consistent with acute HIV infection.

Match each immunocompromised patient scenario with the most appropriate antimicrobial prophylaxis or maintenance regimen.