A 71-year-old woman is evaluated in the intensive care unit for progressive abdominal dist… — USMLE Step 2 CK

A 71-year-old woman is evaluated in the intensive care unit for progressive abdominal distension and altered mental status. She was admitted four days ago for severe *Clostridioides difficile* infection and was appropriately started on oral vancomycin. Today, she is lethargic and confused. Her temperature is $38.9^\circ\text{C}$ ( $102.0^\circ\text{F}$ ), blood pressure is $84/52\text{ mm Hg}$ , pulse is $124/\text{min}$ , and respiratory rate is $22/\text{min}$ . Physical examination reveals a markedly distended, tympanitic abdomen with diffuse tenderness. Bowel sounds are absent. She has had no bowel movements in the past $24$ hours. Laboratory studies show a leukocyte count of $32,000/\text{mm}^3$ and a serum creatinine level of $2.3\text{ mg/dL}$ . An abdominal radiograph demonstrates colonic dilation measuring $9\text{ cm}$ in the transverse colon, with loss of haustral markings and no free intraperitoneal air. Which of the following is the most appropriate next step in the management of this patient's infection?

Add intravenous metronidazole and administer vancomycin per rectumCevap
B
Discontinue oral vancomycin and initiate intravenous vancomycin
C
Substitute oral vancomycin with oral fidaxomicin
D
Add intravenous piperacillin-tazobactam to the current regimen
E
Discontinue oral vancomycin and perform fecal microbiota transplantation

Cevap

Add intravenous metronidazole and administer vancomycin per rectum

This patient is experiencing fulminant *Clostridioides difficile* infection (CDI) complicated by toxic megacolon. Fulminant CDI is characterized by hypotension or shock, ileus, or megacolon. Because she has developed a paralytic ileus (indicated by absent bowel sounds and cessation of stool), orally administered vancomycin will not reach the colon to exert its effect. In this scenario, guidelines mandate shifting to intravenous metronidazole (which is delivered to the inflamed colon via the bloodstream) combined with vancomycin administered per rectum via enema to ensure direct mucosal contact. Furthermore, surgical consultation for possible subtotal colectomy is required if medical management fails.

Adım Adım Çözüm

Diagnose the patient's acute complication based on vital signs, physical exam, and imaging.

The patient has fulminant *Clostridioides difficile* infection complicated by toxic megacolon (dilation

>6\text{ cm}

) and an ileus (absent bowel sounds, no stool output).

Hypotension, altered mental status, and a leukocyte count

>15,000/\text{mm}^3

establish fulminant disease, while imaging confirms toxic megacolon.

Identify the pharmacokinetic barrier created by the complication.

The development of a paralytic ileus prevents enterally administered medications from reaching the colon.

Oral vancomycin will pool in the stomach and proximal small bowel, failing to exert a localized effect on the colonic mucosa.

Select the appropriate alternative routes of administration for targeted pharmacotherapy.

The correct regimen requires dual therapy bypassing the proximal GI tract: intravenous metronidazole and vancomycin administered via retention enema.

Intravenous metronidazole achieves therapeutic concentrations in the inflamed colonic tissue via systemic circulation, and rectal vancomycin ensures direct topical delivery to the distal colon.

Anahtar Kavram

Management of fulminant Clostridioides difficile infection with ileus

Soru

Cevap

Adım Adım Çözüm

Anahtar Kavram

Sık Yapılan Hatalar

Konular

Bu konudan daha fazla soru