Pocket Medicine: The Massachusetts General Hospital Handbook of Internal Medicine (39 page)

± stool ELISAs (viruses,
Crypto
,
Giardia
), serologies (
E. histolytica
), special stool cx

•
Imaging/endoscopy
: CT/KUB if ? toxic megacolon; sig/colo if immunosupp or cx

•
Ddx
: infxn vs. preformed toxin vs. med-induced vs. initial presentation of chronic diarrhea
Treatment

• If none of the above warning signs
and
Pt able to take POs → supportive Rx only: oral hydration, loperamide, bismuth subsalicylate (avoid anticholinergics) • If moderate dehydration: 50–200 mL/kg/d of oral solution (
¹
/
₂
tsp salt, 1 tsp baking soda, 8 tsp sugar, & 8 oz OJ diluted to 1 L w/ H
₂
O) or Gatorade,
etc.
If severe, LR IV.

• For traveler’s diarrhea, bismuth or rifaximin useful for prophylaxis & empiric Rx •
Empiric
abx for non–hospital-acquired
inflammatory
diarrhea reasonable: FQ × 5–7 d

abx rec for
Shigella
, cholera,
Giardia
, amebiasis,
Salmonella
if Pt >50 y or immunosupp or hospitalized, ?
Campylobacter
(if w/in 4 d of sx onset)

avoid
abx if suspect
E. coli
O157:H7 as may ↑ risk of HUS

CLOSTRIDIUM DIFFICILE-ASSOCIATED DIARRHEA (CDAD)

Pathogenesis

• Ingestion of
C. difficile
spores → colonization when colonic flora Dd by abx or chemo → release of toxin A/B → colonic mucosal necrosis & inflammation → pseudomembranes • ↑ toxigenic strain (NAP 1/027) ↑ mort. & length of hosp (esp. in elderly) (
NEJM
2008;359:1932) • Additional risk factors: elderly, nursing home residents, IBD, PPI (
CID
2011;53:1173)
Clinical manifestations
(a spectrum of disease)
• Asx colonization: <3% healthy adults; ~20% in hospitalized patients on antibiotics • Acute watery diarrhea (occ bloody) ± mucus, often w/ lower abd pain, fever, ↑↑↑ WBC

• Pseudomembranous colitis: above sx + pseudomembranes + bowel wall thickening • Fulminant colitis (2–3%):
toxic megacolon
(colon dilatation ≥6 cm on KUB, colonic

atony, systemic toxicity) and/or bowel perforation

Diagnosis

• Only test if
symptomatic
; test
liquid
stool (unless concern for ileus) •
Stool EIA
: detects toxin B and/or A (1–2% strains make A); fast (2–6 h); most often used •
PCR
: quick, becoming test of choice (
Mayo
2012;87:643) • Alternative is 2-step method: ✓ glutamate dehydrogenase (GDH) EIA (high Se,
even if no toxin production), then if
, ✓ cytotoxin assay or toxigenic cx • Consider flex sig if dx uncertain and/or evidence of no improvement w/ standard Rx
Treatment
(
Infect Control Hosp Epidemiol
2010;31:431)
• Start contact precautions; if possible d/c abx ASAP; stop antimotility agents •
Mild-Moderate
(WBC <15k, Cr <1.5 × baseline, age <65 y and no peritoneal sx): MNZ 500 mg PO tid × 10–14 d •
Severe
(WBC >15k or Cr >1.5× baseline or age ≥65 y): vanco 125 mg PO qid × 10–14 d •
Complicated
(ileus, malabsorption, shock, megacolon, peritonitis): vanco 500 mg PO q6h
and
MNZ 500 mg IV q8h; PR vanco if ileus, but avoid if evidence of toxic megacolon; abd CT & urgent surg consult re: colectomy; ? IVIG fidaxomicin 200 mg bid noninferior to vanco PO & ↓ rate of recurrence (
NEJM
2011;364:422) • If Pt needs to stay on original abx, continue
C. diff
. Rx for ≥7 d post-abx cessation • Stool carriage may persist 3–6 wk postcessation of sx and should not trigger further Rx •
Recurrent infection
: 15–30% risk after d/c of abx, most w/in 2 wk of stopping abx

1st relapse: if mild; repeat 14-d course of MNZ or vanco

2nd relapse: PO vanco taper for 6 wk

>2 relapses: vanco taper & adjunctive Rx such as
S. boulardii
, probiotics, rifaximin, nitazoxanide, fidaxomicin or cholestyramine (binds vanco so cannot take concurrently)

Fecal transplant in refractory disease appears safe and effective (
Clin Gas Hep
2011;9:1044;
NEJM
2013;368:407)

• Probiotics may prevent CDAD by 66% in non-immunosuppressed Pts (
Annals
2012;157:878)

CHRONIC DIARRHEA (>4 wk;
Gastro
2004;127:287)

Medications
(cause ↑ secretion, ↑ motility, Δ flora, ↑ cell death or inflammation)
• PPI, colchicine, abx, H2RA, SSRIs, ARBs, NSAIDs, chemo, caffeine
Osmotic
(↓ diarrhea with fasting,
fecal fat, ↑ osmotic gap)
•
Lactose intolerance
: seen in 75% nonwhites & in 25% whites; can be acquired after gastroenteritis, med illness, GI surgery. Clinical: bloating, flatulence, discom-fort, diarrhea. Dx: hydrogen breath test or empiric lactose-free diet. Rx: lactose-free diet, use of lactose-free dairy products and lactase enzyme tablets.

• Other: lactulose, laxatives, antacids, sorbitol, fructose
Malabsorption
(↓ diarrhea with fasting, ↑ fecal fat, ↑ osmotic gap)
•
Celiac disease
(
NEJM
2012;367:2419)

Immune rxn in genetically predisposed Pts (~1% pop) to gliadin, a component of gluten (wheat protein) → small bowel inflammatory infiltrate → crypt hyperplasia, villus atrophy → impaired intestinal absorption

Other s/s: Fe/folate defic anemia; osteoporosis; dermatitis herpetiformis (pruritic papulovesicular); ↑ AST/ALT

Dx: IgA tissue transglutaminase or endomysial Abs ~90% Se & >98% Sp (
JAMA
2010;303:1738). Small bowel bx
and
clinical/serologic response to gluten-free diet definitive.

Rx: gluten-free diet; 7–30% do not respond to diet → ? wrong dx or noncompliant

Complic: ~5% refractory (sx despite strict dietary adherence), risk of T-cell lymphoma and small bowel adenocarcinoma

•
Whipple’s disease
: infxn w/
T. whipplei
(
NEJM
2007;365:55)

Other s/s: fever, LAN, edema, arthritis, CNS Ds, gray-brown skin pigmentation, AI & MS, oculomasticatory myorhythmia (eye oscillations + mastication muscle contract)

Rx: (PCN + streptomycin) or 3rd-gen ceph × 10–14 d → Bactrim for ≥1 y

•
Small Intestinal bacterial overgrowth
(SIBO;
Inf Dis Clin
2010;24:943): ↑ SI bacteria from incompetent/absent ileocecal valve, s/p RYGB, scleroderma, diabetes, s/p vagotomy → fat & CHO malabsorption. Dx:
^1
4
C-xylose & H
⁺
breath tests; Rx: cycled abx (eg, MNZ, FQ, rifaximin) •
Pancreatic insufficiency
: most commonly from chronic pancreatitis or pancreatic cancer •
↓ bile acids
due to ↓ synthesis (cirrhosis) or cholestasis (PBC) → malabsorption • Other: s/p short bowel resection (short bowel syndrome), Crohn’s disease, chronic mesenteric ischemia, eosinophilic gastroenteritis, intestinal lymphoma, tropical sprue
Inflammatory
(
FOB, fever, abd pain,
fecal WBC or lactoferrin or calprotectin)
•
Infections
: particularly parasitic (incl above pathogens &
Strongyloides
), CMV, TB