Infectious Diseases

A 19-year-old college student is admitted to the hospital with a two-day history of fever, severe headache, photophobia, and neck stiffness. On physical examination, the patient is alert but uncomfortable. Temperature is 38.6°C (101.5°F), blood pressure is 118/76 mm Hg, and pulse is 98/min. Nuchal rigidity is present. A lumbar puncture is performed, and empiric intravenous ceftriaxone and vancomycin are initiated. Cerebrospinal fluid (CSF) analysis reveals a leukocyte count of 140/mm³ with 92% lymphocytes, a glucose level of 65 mg/dL (serum glucose 90 mg/dL), and a protein level of 40 mg/dL. Gram stain reveals no organisms. A multiplex polymerase chain reaction (PCR) assay of the CSF is positive for enterovirus and negative for all common bacterial pathogens. Which of the following is the most appropriate next step in this patient's pharmacologic management?

Following a deceased-donor renal allograft transplantation eight months ago, a 58-year-old woman is admitted to the hospital due to a three-week history of productive cough, night sweats, and new-onset left-sided hemiparesis. Her immunosuppressive regimen includes tacrolimus, mycophenolate mofetil, and prednisone. Routine post-transplant antimicrobial prophylaxis was discontinued two months ago. Vital signs show a temperature of 38.2°C (100.8°F). Neurological examination reveals 3/5 strength in the left upper and lower extremities. A chest radiograph demonstrates a large cavitary lesion in the right upper lobe. Subsequent magnetic resonance imaging of the brain reveals a 2.5-cm ring-enhancing lesion in the right frontal lobe with surrounding vasogenic edema. Bronchoscopy with bronchoalveolar lavage is performed, and cytological analysis reveals branching, filamentous, Gram-positive rods that stain weakly positive with a modified acid-fast stain. Which of the following is the most appropriate initial targeted pharmacotherapy for this patient's underlying infection?

On the third day of hospitalization, a $34$-year-old woman is re-evaluated during morning rounds. She was initially admitted for severe right flank pain, dysuria, nausea, and a temperature of $39.2^\circ\text{C}$ ($102.6^\circ\text{F}$). She was empirically started on intravenous ceftriaxone for acute pyelonephritis. Today, the patient reports significant improvement in her symptoms and has tolerated a regular diet since yesterday evening. Her temperature is $37.1^\circ\text{C}$ ($98.8^\circ\text{F}$), blood pressure is $118/76\text{ mm Hg}$, and pulse is $78/\text{min}$. Right costovertebral angle tenderness is no longer present. Blood cultures obtained at admission have shown no growth. Urine culture results are now available and demonstrate $>10^5\text{ CFU/mL}$ of *Escherichia coli*. The organism is susceptible to ciprofloxacin, ceftriaxone, and meropenem; it is resistant to ampicillin and trimethoprim-sulfamethoxazole. Based on the patient's current clinical status and laboratory findings, which of the following is the most appropriate next step in management?

Match each clinical presentation of pneumonia with the most likely causative pathogen based on classic epidemiological risk factors and clinical findings.

A 68-year-old woman is brought to the emergency department by her daughter due to progressive confusion, fever, and a severe headache over the past 24 hours. The patient has a history of rheumatoid arthritis treated with methotrexate and infliximab. Temperature is 39.1°C (102.4°F), blood pressure is 105/65 mm Hg, pulse is 115/min, and respirations are 20/min. Neurologic examination reveals a lethargic patient who only opens her eyes to painful stimuli. There is marked nuchal rigidity. Papilledema is absent, and there are no focal motor deficits. The physician suspects bacterial meningitis. Arrange the following management steps in the most appropriate chronological order for this patient.

A 64-year-old man is brought to the emergency department by his spouse due to worsening confusion, a severe global headache, and a high fever over the last 24 hours. His temperature is 39.4°C (102.9°F), blood pressure is 128/82 mmHg, and heart rate is 114/min. Physical examination shows a lethargic patient who only opens his eyes to painful stimuli. Marked resistance to passive neck flexion is present. Funduscopic examination reveals bilateral blurring of the optic disc margins with absent venous pulsations. Arrange the following steps in the most appropriate chronological order for managing this patient's condition.

A 24-year-old woman presents to the outpatient clinic with a 2-day history of burning with urination and increased urinary frequency. She reports no fever, chills, back pain, or vaginal discharge. She is sexually active with one male partner and uses condoms inconsistently. Her last menstrual period was 2 weeks ago. Vital signs are temperature 37.0°C (98.6°F), blood pressure 110/70 mmHg, pulse 78/min, and respirations 14/min. Physical examination reveals mild suprapubic tenderness but no costovertebral angle tenderness. A urine pregnancy test is negative. Urinalysis is positive for leukocyte esterase and nitrites. Which of the following is the most appropriate pharmacotherapy for this patient?

A medical team is reviewing the chart of an inpatient being treated for a severe right-sided soft tissue infection. The patient, who has a history of well-controlled type 2 diabetes mellitus, presented two days ago with rigors, marked localized erythema, and a temperature of 39.0 C (102.2 F). Upon admission, blood cultures were drawn, and empiric intravenous vancomycin and piperacillin-tazobactam were initiated. Today, the patient is clinically stable and afebrile. The microbiology laboratory reports that both sets of admission blood cultures are growing Staphylococcus aureus. Susceptibility testing indicates the isolate is sensitive to oxacillin, cefazolin, and clindamycin, but resistant to penicillin and ampicillin. Which of the following is the most appropriate next step in the pharmacologic management of this patient?

A 71-year-old female resident of a long-term care facility was admitted to the hospital $4$ days ago with a temperature of $39.0^{\circ}\text{C}$ ($102.2^{\circ}\text{F}$), rigors, and severe left-sided flank pain. Initial evaluation revealed marked left costovertebral angle tenderness. Laboratory testing demonstrated a leukocyte count of $15,200/\mu\text{L}$ with a left shift. Urinalysis was strongly positive for leukocyte esterase, nitrites, and numerous bacteria. The patient was started on empiric intravenous meropenem and intravenous fluids.

Today (hospital day 4), the patient is hemodynamically stable, has been afebrile for the past $48$ hours, and her flank pain has significantly improved. She is eating a normal diet and is eager to return to her facility. Blood cultures drawn on admission remain negative. The admission urine culture grew $>100,000$ colony-forming units/mL of *Escherichia coli*. Susceptibility testing results for the isolate are as follows:

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

A 31-year-old man with a known history of intravenous drug use presents to the emergency department complaining of high fever, severe chills, and generalized malaise for the past three days. Vital signs demonstrate a temperature of $39.0^\circ\text{C}$ ($102.2^\circ\text{F}$), blood pressure of $112/68\text{ mmHg}$, heart rate of $118/\text{min}$, and respiratory rate of $20/\text{min}$. Physical examination reveals a new blowing holosystolic murmur that is loudest at the left lower sternal border, along with pinpoint, non-tender, erythematous macules on his palms. Arrange the following management steps in the most appropriate chronological order for this patient.

Match each clinical presentation of an opportunistic infection in a patient with advanced HIV to its most appropriate first-line targeted antimicrobial therapy.

Match each highly specific clinical scenario of an infectious disease with the most appropriate targeted pharmacologic management or intervention step, considering the patient's unique contraindications and risk factors.

A 28-year-old woman visits her primary care clinic due to a spreading rash on her right leg. She first noticed a small red bump four days ago, which has since expanded. The patient returned from a week-long camping trip in Connecticut ten days ago. She reports mild fatigue and muscle aches but denies fever, joint swelling, neck stiffness, or facial asymmetry. Her vital signs are within normal limits. Physical examination reveals a 9-cm erythematous annular plaque with central clearing on the right posterior calf. The lesion is flat, non-tender, and non-pruritic. Neurological and cardiovascular examinations are unremarkable. Which of the following is the most appropriate next step in management?

A $68$-year-old man is admitted to the general medical floor with a $4$-day history of fever, chills, and a cough productive of rust-colored sputum. His past medical history is significant only for benign prostatic hyperplasia. He has not had any recent hospitalizations, does not reside in a nursing facility, and has not received any antibiotics in the past year. Vital signs on presentation include a temperature of $38.8^{\circ}\text{C}$ ($101.8^{\circ}\text{F}$), blood pressure of $115/76\text{ mm Hg}$, pulse of $102/\text{min}$, and respiratory rate of $24/\text{min}$. Oxygen saturation is $94\%$ on $2\text{ L/min}$ via nasal cannula. Chest radiography demonstrates a dense consolidation in the left lower lobe. The admitting physician empirically prescribes intravenous piperacillin-tazobactam and vancomycin. A high-quality sputum Gram stain demonstrates many polymorphonuclear leukocytes and abundant Gram-positive diplococci. Which of the following is the most appropriate modification to this patient's antimicrobial regimen?

A 54-year-old man is brought to the emergency department by his partner due to a 24-hour history of severe headache, high fever, and worsening confusion. He has a history of advanced HIV infection and has been non-adherent to his antiretroviral therapy. His temperature is 39.4°C (102.9°F), blood pressure is 105/65 mmHg, and heart rate is 118/min. He is lethargic and oriented only to person. Physical examination is notable for marked resistance to passive neck flexion. Fundoscopic evaluation reveals blurring of the optic disc margins bilaterally. Arrange the following diagnostic and therapeutic interventions in the most appropriate chronological order for the immediate management of this patient.

For each of the following classic clinical presentations of infectious diseases, select the most appropriate first-line targeted antimicrobial therapy.

Match each clinical presentation of infective endocarditis or severe bacteremia to its most appropriate targeted antimicrobial regimen.

A $54$-year-old man undergoing induction chemotherapy for acute myeloid leukemia presents to the emergency department with a new-onset fever of $38.9^\circ\text{C}$ ($102.0^\circ\text{F}$) and chills. He has an indwelling central venous catheter. His blood pressure is $105/65 \text{ mm Hg}$, heart rate is $112/\text{min}$, and respiratory rate is $18/\text{min}$. Physical examination reveals no obvious source of infection, and the catheter site appears clean without erythema or fluctuance. Laboratory studies demonstrate an absolute neutrophil count of $200/\mu\text{L}$. Arrange the following management steps in the most appropriate chronological sequence for this patient.

A 68-year-old woman is evaluated in the preoperative clinic prior to an elective right total knee arthroplasty. Her past medical history is notable for osteoarthritis and well-controlled hypertension. The patient reports feeling well and specifically denies any dysuria, urinary frequency, suprapubic pain, or fever. Her vital signs are within normal limits. As part of her preoperative workup, a urinalysis is obtained which demonstrates 15 white blood cells per high-power field and is positive for leukocyte esterase and nitrites. A subsequent urine culture grows >$10^5$ colony-forming units/mL of *Escherichia coli*. Susceptibility testing shows the organism is sensitive to nitrofurantoin, trimethoprim-sulfamethoxazole, ciprofloxacin, and ceftriaxone. Which of the following is the most appropriate next step in the management of this patient?

A $32$-year-old man comes to the clinic for routine sexually transmitted infection screening. He is currently asymptomatic and has no history of genital ulcers, diffuse rashes, or neurologic symptoms. He reports having unprotected intercourse with a new male sexual partner $2$ months ago. He has no known prior history of syphilis or other sexually transmitted infections. Vital signs are within normal limits. Physical examination reveals no oral, genital, or perianal lesions, and no lymphadenopathy is appreciated. The clinic laboratory utilizes the reverse sequence algorithm for syphilis screening. The initial *Treponema pallidum* enzyme immunoassay (EIA) returns reactive. A reflex rapid plasma reagin (RPR) test is nonreactive. Which of the following is the most appropriate next step in management?