Infectious Diseases

Various parasitic infections require specific antimicrobial agents based on their pathogenesis and the patient's clinical syndrome. For each patient vignette described below, select the most appropriate definitive treatment regimen.

A 42-year-old man presents to the emergency department triage desk with a 4-week history of productive cough, hemoptysis, night sweats, and a 5-kg (11-lb) unintentional weight loss. He is actively coughing in the waiting area. He recently immigrated from a region with high tuberculosis endemicity.

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

A 62-year-old man is evaluated on postoperative day 4 for a temperature of 38.6°C (101.5°F). He recently underwent an exploratory laparotomy and small bowel resection for mesenteric ischemia. His medical history includes hypertension and type 2 diabetes mellitus. A right internal jugular central venous catheter, placed during the surgery, remains in situ. Physical examination shows a clean surgical incision with no erythema or purulent drainage. The catheter site is without induration, erythema, or tenderness. There is no calf tenderness or swelling. Urinalysis is unremarkable. Two sets of blood cultures (one from the central line and one from a peripheral vein) were drawn, and empiric intravenous vancomycin and piperacillin-tazobactam were initiated. Today (postoperative day 6), the patient's temperature is 37.2°C (99.0°F) and he is tolerating an oral diet. The microbiology laboratory reports that 1 of the 4 blood culture bottles (the aerobic bottle drawn from the central line) grew Staphylococcus epidermidis at 36 hours of incubation. The peripheral blood culture and the anaerobic central line culture bottle remain sterile. Which of the following is the most appropriate next step in management?

A 54-year-old woman is hospitalized for induction chemotherapy to treat acute myeloid leukemia. On day $10$ of her hospital stay, she develops a new-onset fever. She reports no cough, dyspnea, dysuria, or abdominal pain. Temperature is $38.8^\circ\text{C}$ ($101.8^\circ\text{F}$), blood pressure is $112/74$ mm Hg, pulse is $98$/min, and respirations are $16$/min. Physical examination reveals a clean and intact right internal jugular central venous catheter site with no surrounding erythema, induration, or tenderness. Lungs are clear to auscultation. Cardiovascular and abdominal examinations are unremarkable. Skin examination shows no rashes or lesions.

Laboratory studies:
Leukocytes: $400/\text{mm}^3$
Absolute neutrophil count: $80/\text{mm}^3$
Hemoglobin: $9.2$ g/dL
Platelets: $45,000/\text{mm}^3$
Serum creatinine: $0.9$ mg/dL

Blood and urine cultures are obtained. Which of the following is the most appropriate empiric pharmacotherapy for this patient?

A 26-year-old man comes to the clinic requesting sexually transmitted infection screening. He reports a condomless sexual encounter with a partner of unknown serostatus approximately 3 weeks ago. He currently feels well and reports no fever, rash, sore throat, or lymphadenopathy. The physician decides to screen for HIV. Assuming the patient has indeed contracted HIV from this recent encounter, arrange the following steps in the correct chronological order according to the standard diagnostic algorithm for acute HIV infection.

A $68$-year-old woman presents to the outpatient clinic for evaluation of a right foot ulcer. She has a $15$-year history of type $2$ diabetes mellitus, which is complicated by severe peripheral neuropathy and chronic kidney disease. The patient first noticed the ulcer $3$ weeks ago. She reports no fevers, chills, or foot pain. Vital signs show a temperature of $37.1^\circ\text{C}$ ($98.8^\circ\text{F}$), blood pressure of $132/78$ mm Hg, and heart rate of $76$/min. Physical examination reveals a $2 \times 2$ cm ulcer on the plantar surface of the first metatarsal head. There is no surrounding erythema, warmth, fluctuance, or purulent drainage. A sterile metal probe is inserted into the ulcer and palpates hard, gritty tissue at the base. Laboratory studies reveal a leukocyte count of $8,200/\text{mm}^3$ and an erythrocyte sedimentation rate of $88$ mm/h. Plain radiography of the right foot demonstrates periosteal elevation and cortical erosion of the first metatarsal head. Which of the following is the most appropriate next step in the management of this patient?

A 24-year-old man presents to the clinic requesting sexually transmitted infection screening after a high-risk sexual encounter two weeks ago. He reports a mild sore throat, low-grade fever, and fatigue over the past few days. The physician suspects acute HIV infection. Arrange the following steps in the correct chronological sequence for the diagnosis and initial management of this patient, assuming he is ultimately confirmed to have acute HIV-1 infection.

Match each clinical presentation of infective endocarditis with the most appropriate targeted antimicrobial regimen based on current consensus guidelines.

Match each clinical presentation of an infectious disease to its most appropriate, targeted first-line pharmacotherapy.

Match each clinical presentation of a sexually transmitted infection to its most appropriate definitive antimicrobial management strategy based on current guidelines.

A $78$-year-old man is brought to the emergency department from a skilled nursing facility due to a $2$-day history of progressively worsening confusion, profound lethargy, and severe constipation. His past medical history is significant for advanced prostate cancer with known bone metastases, benign prostatic hyperplasia, and the presence of a chronic indwelling urethral catheter.

Upon arrival, his temperature is $37.1^\circ\text{C}$ ($98.8^\circ\text{F}$), blood pressure is $136/84\text{ mm Hg}$, pulse is $76/\text{min}$, and respirations are $14/\text{min}$. He is difficult to arouse but oriented to person when awakened. Physical examination reveals markedly dry mucous membranes and poor skin turgor. His abdomen is soft and non-tender, and there is no costovertebral angle or suprapubic tenderness.

Laboratory evaluation shows:
- Leukocyte count: $8,200/\text{mm}^3$
- Hemoglobin: $10.4\text{ g/dL}$
- Serum creatinine: $1.8\text{ mg/dL}$ (baseline $1.0\text{ mg/dL}$)
- Blood urea nitrogen: $42\text{ mg/dL}$
- Serum calcium: $13.8\text{ mg/dL}$
- Serum albumin: $3.5\text{ g/dL}$

Urinalysis reveals cloudy urine with positive leukocyte esterase, positive nitrites, and $45-50\text{ white blood cells/hpf}$.

The patient is admitted and aggressively treated with intravenous normal saline and calcitonin, resulting in a rapid improvement in his mental status over the next $24$ hours. However, a urine culture obtained at the time of admission now grows $>10^5\text{ CFU/mL}$ of *Escherichia coli*. The isolate is resistant to ciprofloxacin but susceptible to ceftriaxone, cefepime, and meropenem.

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

Evaluation for hospital discharge is being performed for a $67$-year-old male recovering from community-acquired pneumonia. Upon initial admission $3$ days ago, he presented with a temperature of $39.1^\circ C$ ($102.4^\circ F$), productive cough, and right lower lobe consolidation on chest radiography. Empiric treatment was initiated with intravenous ceftriaxone and azithromycin. Currently, he has been afebrile for $28$ hours, his respiratory rate is $16$/min, and oxygen saturation is $96\%$ on room air. He is ambulating well and tolerating a regular diet. Blood cultures obtained at admission have finalized, growing *Streptococcus pneumoniae*. Antimicrobial susceptibility testing indicates the isolate is susceptible to penicillin (MIC $\leq 0.03 \mu$ g/mL), amoxicillin, ceftriaxone, levofloxacin, and linezolid. Based on these findings, which of the following is the most appropriate antimicrobial strategy for discharge?

A $61$-year-old woman with a known history of advanced HIV (recent CD4 count $85/\text{mm}^3$) arrives at the emergency department accompanied by her daughter. She has a $2$-day history of progressively severe generalized headache, subjective fevers, and profound lethargy. Upon arrival, her temperature is $39.2^\circ\text{C}$ ($102.6^\circ\text{F}$), blood pressure is $110/65\text{ mmHg}$, pulse is $112/\text{min}$, and respirations are $18/\text{min}$. On physical examination, she is difficult to arouse and oriented only to person. Neck flexion produces involuntary hip and knee flexion. Neurologic evaluation reveals that the right pupil is $4\text{ mm}$ and sluggishly reactive, while the left is $2\text{ mm}$ and briskly reactive. Arrange the following diagnostic and therapeutic steps in the optimal chronological sequence for this patient's initial management.

A $32$-year-old woman comes to the clinic reporting facial pressure and nasal congestion that began $5$ days ago. She states her symptoms started with a mild scratchy throat and clear rhinorrhea but have since progressed. Over the past two days, she has noticed thick, yellow-green nasal discharge and worsening pressure over her cheeks, which is exacerbated when leaning forward. She reports a subjective mild fever at home two days ago but has been afebrile since. Her medical history is unremarkable, and she takes no daily medications. Her temperature is $37.2^\circ\text{C}$ ($99.0^\circ\text{F}$), blood pressure is $118/76\text{ mmHg}$, and pulse is $78/\text{min}$. Physical examination reveals erythematous, edematous nasal mucosa with purulent drainage in the bilateral middle meatus. There is mild tenderness to palpation over the maxillary sinuses. Which of the following is the most appropriate next step in management?

Match each clinical presentation of an opportunistic infection in a patient with advanced HIV to the most appropriate first-line induction or targeted pharmacological therapy.

A $54$-year-old man comes to the emergency department due to a $3$-day history of high fevers, chills, drenching sweats, and extreme fatigue. He resides in coastal Massachusetts and frequently hikes in wooded areas. His past medical history is notable for hereditary spherocytosis, for which he underwent a splenectomy at age $20$. His temperature is $39.2^\circ\text{C}$ ($102.6^\circ\text{F}$), blood pressure is $110/70\text{ mmHg}$, pulse is $115/\text{min}$, and respirations are $18/\text{min}$. Physical examination reveals scleral icterus and pale conjunctivae. There is no rash or lymphadenopathy. Laboratory studies show:

- Hemoglobin: $8.2\text{ g/dL}$
- Platelet count: $95,000/\text{mm}^3$
- Leukocyte count: $9,400/\text{mm}^3$
- Total bilirubin: $4.1\text{ mg/dL}$ (direct: $0.6\text{ mg/dL}$)
- Lactate dehydrogenase: $850\text{ U/L}$

A peripheral blood smear demonstrates intraerythrocytic pleomorphic ring forms and occasional tetrad structures. Which of the following is the most appropriate pharmacotherapy for this patient's condition?

An unconscious adult patient in the intensive care unit is currently receiving mechanical ventilation following a complicated abdominal surgery performed a week ago. The nursing staff reports a sudden increase in the volume of thick, purulent pulmonary secretions. The patient's core body temperature has risen to 39.1°C (102.4°F), and ventilator settings have been adjusted due to worsening hypoxia. A bedside chest radiograph demonstrates a dense, new consolidation in the right middle lobe, leading to a presumptive diagnosis of ventilator-associated pneumonia (VAP).

What is the correct chronological order of the following clinical actions to optimize both patient outcomes and antimicrobial stewardship?

A $42$-year-old man who recently emigrated from a region with highly endemic tuberculosis is admitted to the hospital due to a $6$-week history of worsening productive cough, drenching night sweats, and a $5$-kg weight loss. His vital signs show a temperature of $38.2^\circ C$ ($100.8^\circ F$). A chest radiograph reveals a distinct cavitary lesion in the apical segment of the right upper lobe.

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

A 48-year-old woman is hospitalized in the hematology-oncology unit undergoing induction chemotherapy for acute myeloid leukemia. On hospital day 12, she develops chills and a new-onset fever. Her temperature is 38.7°C (101.7°F), blood pressure is 110/68 mm Hg, and pulse is 112/min. Physical examination reveals a clean central venous catheter insertion site and no focal signs of infection. Her absolute neutrophil count is 100/mm³. Two sets of blood cultures are obtained, and empiric therapy with intravenous cefepime is initiated. Forty-eight hours later, the patient is alert and her temperature has normalized to 37.2°C (99.0°F). Her vital signs are stable, and her absolute neutrophil count is now 150/mm³. The initial blood cultures are finalized, showing growth of Klebsiella pneumoniae in both sets. Susceptibility testing demonstrates that the isolate is sensitive to ceftriaxone, cefepime, piperacillin-tazobactam, and meropenem, but resistant to ampicillin.

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

Match each clinical exposure or presentation with the most appropriate empiric antimicrobial therapy or post-exposure prophylaxis.