Infectious Diseases

Match each clinical scenario to the most appropriate first-line antimicrobial therapy.

A 65-year-old man is evaluated in the intensive care unit for recent fever. He was admitted 10 days ago for severe acute pancreatitis and required aggressive fluid resuscitation via a right internal jugular central venous catheter. Two days ago, he developed a temperature of $38.9^\circ\text{C}$ ($102.0^\circ\text{F}$) and tachycardia. The central catheter was removed, and peripheral blood cultures were drawn. Empiric intravenous vancomycin and cefepime were initiated. Today, the patient is afebrile and hemodynamically stable. Both sets of blood cultures are positive for *Enterococcus faecalis*. Susceptibility testing demonstrates that the isolate is susceptible to ampicillin, vancomycin, and daptomycin, but resistant to cefepime. Which of the following is the most appropriate next step in this patient's antimicrobial therapy?

A $35$-year-old man with a history of advanced HIV (CD4 count of $45 \text{ cells/mm}^3$) is brought to the emergency department by his partner due to $2$ days of fever, severe headache, and progressive confusion. His temperature is $39.2^\circ\text{C}$ ($102.6^\circ\text{F}$), blood pressure is $110/70 \text{ mmHg}$, and pulse is $115/\text{min}$. Physical examination reveals nuchal rigidity and a positive Brudzinski sign. He is lethargic but withdraws all extremities to pain. Fundoscopic examination shows early papilledema. Suspecting acute bacterial meningitis, the physician decides on a management plan. Arrange the following steps in the most appropriate chronological order of execution for this patient.

A 48-year-old man is brought to the emergency department by his wife due to a severe headache, fever, and confusion that began 24 hours ago. His temperature is 39.1°C (102.4°F), blood pressure is 142/86 mmHg, pulse is 110/min, and respirations are 18/min. Physical examination reveals nuchal rigidity. Neurologic examination shows a new-onset right-sided facial droop and right upper extremity weakness. Suspecting acute bacterial meningitis, the physician prepares to initiate the management workup. Arrange the following steps in the most appropriate chronological order of execution.

An 82-year-old woman residing in a skilled nursing facility is brought to the outpatient clinic by her daughter for a routine follow-up visit. The daughter reports that over the past $3$ days, the patient's urine has appeared unusually cloudy and has a strong, foul odor. The patient has a medical history of Alzheimer dementia, hypertension, and osteoarthritis. She does not report any pain, and the daughter has not noticed any changes in her mother's baseline mental status, oral intake, or behavioral patterns. Vital signs are temperature $37.1^\circ\text{C}$ ($98.8^\circ\text{F}$), pulse $76$/min, blood pressure $130/75$ mm Hg, and respirations $14$/min. Physical examination reveals a pleasant woman who is oriented to person only, which is at her baseline. The abdomen is soft and non-tender. There is no suprapubic or costovertebral angle tenderness. A clean-catch urine sample is obtained, and urinalysis shows:

pH: 7.0
Specific gravity: 1.015
Leukocyte esterase: positive
Nitrites: positive
WBC: 45/hpf
RBC: 2/hpf
Bacteria: numerous

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

A 26-year-old woman is evaluated on the medical ward on hospital day $3$. She was initially admitted for severe right-sided flank pain, nausea, vomiting, and a temperature of $39.2^\circ\text{C}$ ($102.6^\circ\text{F}$). On admission, urinalysis revealed marked pyuria and bacteriuria, and she was started on empiric intravenous ceftriaxone for acute pyelonephritis.

Today, she reports significant improvement in her symptoms and is tolerating a regular diet. Her temperature is $37.0^\circ\text{C}$ ($98.6^\circ\text{F}$), blood pressure is $118/76\text{ mmHg}$, and pulse is $78\text{/min}$. Physical examination shows resolution of the right costovertebral angle tenderness. Blood cultures drawn on admission show no growth. The urine culture from admission grew $>100,000\text{ CFU/mL}$ of *Escherichia coli*. The isolate susceptibility report is as follows:

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

Match each clinical presentation of community-acquired pneumonia (CAP) with the most appropriate empiric antimicrobial regimen based on current clinical guidelines.

A 58-year-old man is evaluated in the intensive care unit for ongoing antibiotic management. He was admitted 10 days ago following a severe traumatic brain injury that required mechanical ventilation. Five days ago, he developed a new fever of 38.9°C (102.0°F), increased purulent endotracheal secretions, and worsening oxygenation. A portable chest radiograph revealed a new right lower lobe infiltrate. He was empirically started on intravenous vancomycin and piperacillin-tazobactam for presumed ventilator-associated pneumonia. Today, the patient's temperature is 37.2°C (99.0°F), and his oxygen requirements have steadily decreased. A bronchoalveolar lavage culture obtained 48 hours ago has finalized, growing >$10^5$ CFU/mL of methicillin-susceptible *Staphylococcus aureus* (MSSA). Blood cultures drawn at the time of the fever remain sterile. Which of the following is the most appropriate next step in pharmacotherapy?

A 61-year-old man is evaluated in the intensive care unit to optimize his medication regimen. He was admitted a week ago after sustaining multiple severe injuries in a high-speed motorcycle collision. He required immediate intubation and has remained mechanically ventilated. Three days ago, he developed a temperature of $39.0^\circ\text{C}$ ($102.2^\circ\text{F}$), a heart rate of $112/\text{min}$, thick purulent airway secretions, and a leukocytosis of $18,500/\mu\text{L}$. A portable chest radiograph demonstrated a new dense consolidation in the right lower lobe. He was promptly started on a broad-spectrum empiric antimicrobial regimen consisting of intravenous vancomycin, cefepime, and tobramycin.

Today, his clinical trajectory has improved; his temperature is $37.2^\circ\text{C}$ ($99.0^\circ\text{F}$), his heart rate is $85/\text{min}$, and his fraction of inspired oxygen ($\text{FiO}_2$) has been successfully titrated down. Blood cultures drawn three days ago show no growth. A quantitative culture of an endotracheal aspirate obtained at the onset of his fever grew $>10^5\text{ colony-forming units/mL}$ of *Pseudomonas aeruginosa*. The isolate's susceptibility profile is as follows:

Amikacin: Susceptible
Cefepime: Susceptible
Ciprofloxacin: Susceptible
Meropenem: Susceptible
Tobramycin: Susceptible

Routine morning laboratory results reveal a serum creatinine level of $2.2 \text{ mg/dL}$, which has climbed from a baseline of $1.0 \text{ mg/dL}$ on admission.

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

A $62$-year-old man with a history of osteoarthritis and type $2$ diabetes mellitus presents to the emergency department with acute onset of severe right knee pain, swelling, and a fever of $38.8^\circ\text{C}$ ($101.8^\circ\text{F}$). He is unable to bear weight on the right leg. Physical examination reveals a warm, erythematous, and markedly swollen right knee with a severely restricted range of motion due to pain. Arrange the following steps in the most appropriate chronological sequence for the management of this patient's condition.

A 25-year-old man presents to the clinic for a routine health maintenance examination. He has no past medical history and takes no medications. The patient reports having unprotected receptive anal intercourse with a new male partner 4 weeks ago. He is currently asymptomatic. Physical examination reveals normal vital signs and no lymphadenopathy, rash, or mucosal lesions. The patient requests screening for sexually transmitted infections, including HIV.

Arrange the following steps in the most appropriate chronological order for the diagnosis and initial management of this patient's suspected HIV infection, in accordance with current guidelines.

A 47-year-old woman with a history of type 2 diabetes mellitus is evaluated on hospital day 4 for ongoing management of a left foot infection. She initially presented to the emergency department with a deep, purulent ulcer on the plantar surface of her foot, surrounded by a 6-cm area of erythema and induration. On admission, she was febrile and had leukocytosis. She was started on empiric intravenous vancomycin and piperacillin-tazobactam and underwent prompt surgical debridement. The surgeon noted no evidence of bone involvement, which was confirmed by a negative MRI of the foot. Today, her temperature is 37.0°C (98.6°F), blood pressure is 122/78 mm Hg, and pulse is 76/min. The surgical wound is clean with healthy granulation tissue, and the surrounding erythema has nearly resolved. Intraoperative deep tissue cultures now show heavy growth of methicillin-susceptible Staphylococcus aureus (MSSA) and Streptococcus agalactiae. Susceptibility testing indicates both isolates are susceptible to cefazolin, cephalexin, and ampicillin. The MSSA isolate is resistant to clindamycin. Which of the following is the most appropriate next step in pharmacotherapy?

Match each specific clinical presentation and isolated pathogen of infective endocarditis with its most appropriate targeted antimicrobial regimen according to current clinical guidelines.

Match each clinical scenario with the most appropriate antimicrobial therapy or prophylaxis regimen.

During a late June clinic visit in Massachusetts, a $28$-year-old pregnant woman at $18$ weeks gestation presents for evaluation of an expanding rash. She reports feeling unusually fatigued over the past $4$ days, accompanied by a mild headache. Two weeks ago, the patient spent a weekend camping in a heavily wooded area, though she does not recall any specific insect bites. Her medical history is notable for a childhood episode of anaphylaxis following penicillin administration, which required emergent intubation. Vital signs include a temperature of $37.4^\circ\text{C}$, heart rate of $88\text{/min}$, and blood pressure of $110/70\text{ mm Hg}$. Physical examination reveals a $9\text{-cm}$ annular, erythematous plaque with central clearing on the right posterior thigh. The lesion is warm but non-tender. The remainder of the examination, including a detailed neurological assessment, is unremarkable. Which of the following is the most appropriate pharmacotherapy for this patient?

A 58-year-old man is evaluated on hospital day 3 for persistent fever. He was admitted with fever, severe left flank pain, and dysuria, and was diagnosed with acute complicated pyelonephritis. At that time, empiric therapy with intravenous ceftriaxone was initiated.

Today, he reports continued flank pain and malaise. His temperature is $38.6^\circ\text{C}$ ($101.5^\circ\text{F}$), blood pressure is $118/76\text{ mmHg}$, pulse is $102\text{/min}$, and respiratory rate is $18\text{/min}$. Physical examination reveals persistent left costovertebral angle tenderness.

Blood cultures drawn on admission are now positive for *Enterobacter cloacae*. The antimicrobial susceptibility report is as follows:

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

A 54-year-old man is brought to the emergency department by his wife due to a severe, generalized headache, subjective fever, and progressive confusion over the past 24 hours. He has a history of a deceased-donor renal transplant 2 years ago and currently takes tacrolimus and mycophenolate mofetil. His temperature is 39.2°C (102.6°F), blood pressure is 110/70 mmHg, and heart rate is 112/min. On physical examination, the patient is lethargic and oriented only to person. He has marked nuchal rigidity. No papilledema is appreciated, but a detailed neurologic examination is limited by his altered mental status. Arrange the following steps in the most appropriate chronological sequence for the optimal initial management of this patient.

Match the following clinical presentations in patients with advanced HIV/AIDS to their most appropriate definitive pharmacotherapy.

Match each clinical vignette describing a zoonotic or vector-borne infection with its most appropriate targeted antimicrobial therapy.

A 68-year-old man who was intubated and mechanically ventilated 5 days ago for severe acute respiratory distress syndrome (ARDS) develops a new fever of 38.9°C (102.0°F). His oxygen requirements have increased over the past 24 hours, and thick, purulent secretions are suctioned from the endotracheal tube. A portable chest radiograph reveals a new right lower lobe consolidation. Arrange the following steps in the most appropriate chronological sequence for managing this patient's suspected ventilator-associated pneumonia (VAP).