GI Infections of the Small/Large Bowel
Whipples Disease
Definition
Chronic, multi system infection of the Tropherynma whipplei species
a gram positive bacillus
suspected to be agricultural in origin
Risk Factors
Caucasian male
mean age ~50 yo
agricultural work
contaminated sewage, soil or fecal matter in rural communities
Signs and Symptoms
arthralgia (intermittent and migratory)
diarrhea
weight loss
abdominal pain
lymphadenopathy
skin changes
neurologic symptoms
confusion, depression, personality changes
nystagmus, rhythmic contractions of facial muscles (specifically muscles of mastication)
Diagnosis
biopsy
PCR
MUST check CSF PCR in cases with CNS involvement
up to 50% of patients may have characteristic macrophages of Whipple's disease or PCR positive material in the absence of CNS symptoms
positive PCR may indicate remnants of bacterial DNA or colonization
must differentiate from mycobacterium avium complex disease
can also have PAS-positive macrophages
stain for acid-fast bacilli to differentiate
Pathology Findings
villous atrophy
Periodic acid-Schiff (PAS)-positive foamy macrophages in the lamina propria of the small intestine
AFB stain negative
lymphatic dilation
Lab Findings
hypoalbuminemia
positive Tropheryma whipplei PCR
Treatment
First line: Bactrim (one DS tab BID) for at least one year
only the SMX component is active against T. whipplei
In cases of CNS involvement must keep bactrim on until CSF PCR returns negative. Doxycycline has poor CSF penetration
can use doxycycline (200 mg/day) and hydroxychloroquine (600 mg/day) in resistant cases
Severe disease: 2 wks of IV cephalosporin or carbapenem (for CNS penetration) before treatment with bactrim
Increased resistance to tetracycline
No role for anti-parasitic therapy
Versus
Giardiasis - loose stools and bloating, but does NOT have extra luminal manifestations
Tropical sprue - chronic diarrhea, bloating, hypoalbuminemia, but typically in Caribbean and southeastern Asia
Mycobacterium avium - differentiate with AFB stain
C. difficile Infection
Lab Findings
positive glutamate dehydrogenase
positive toxin A/B
Multistep algorithms using PCR for toxin gene(s) or single step PCR on liquid stool samples have the best test performance characteristics
For multistep: sensitivity 0.68-1, specificity 0.92-1
For single step: sensitivity 0.86-0.92, specificity 0.94-0.97
Treatment (***review recent ACG guidelines***)
For severe C. diff infection (CDI) in the general population, success rate of vancomycin is 78.5% with similar success seen with fidaxomicin but with lower recurrence rates
First Line: oral vancomycin or fidaxomicin
Metronidazole is NOT recommended as first line for CDI
ACG: First recurrence
treat with same regimen as the initial episode
IDSA: previously treated with vancomycin
treat with a prolonged taper and pulsed vancomycin regimen
OR treat with fidaxomicin
Fulminant C. difficile infection
oral and rectal vancomycin + IV metronidazole
limited evidence for FMT, IVIT, and fidaxomicin
Currently no role for probiotics in prevention or as adjunctive treatment
insufficient evidence to support discontinuing necessary PPIs as a preventative measure
limited support for extending the length of anti-C diff treatment beyond the recommended treatment course or restarting an anti-C diff agent empirically for those who require treatment with antibiotics shortly after completion of CDI treatment
Cyclospora Infection
Signs and Syptoms
diarrhea - may be with blood or mucus
anorexia
weight loss
low grade fever
may be asymptomatic
Risk Factors
Immunocompromised
HIV
longer duration of infection
Treatment
trimethoprim 150 mg + sulfamethoxazole 800 mg BID for 7 d
extended course in immunocompromised