Which of the following is NOT a cause of secretory diarrhea?

Inflammatory bowel disease (IBD)

Which one of the following statements best characterizes lympho-granuloma venereum (LGV)?

The causative agent is C. trachomatis

It is most common in temperate regions

In the United States, it is more common among women

Penicillin is effective in early treatment

A 19-year-old university student presents to the student clinic with painful joints. He states that over the past week his right wrist has become increasingly stiff. This morning he noticed pain and stiffness in his left ankle and left knee. The patient has celiac disease and takes a daily multivitamin. He says he is sexually active with multiple male and female partners. He smokes marijuana but denies intravenous drug abuse. He recently traveled to Uganda to volunteer at a clinic that specialized in treating patients with human immunodeficiency virus (HIV). He also went on an extended hiking trip last week in New Hampshire. Physical exam reveals swelling of the right wrist and a warm, swollen, erythematous left knee. The left Achilles tendon is tender to palpation. There are also multiple vesicopustular lesions on the dorsum of the right hand. No penile discharge is appreciated. Arthrocentesis of the left knee is performed. Synovial fluid results are shown below: Synovial fluid: Appearance: Cloudy Leukocyte count: 40,000/mm^3 with neutrophil predominance Gram stain is negative. A synovial fluid culture is pending. Which of the following is the patient’s most likely diagnosis?

Disseminated gonococcal infection

A 40-year-old female with multiple sexual partners presented with fever, rash, and articular symptoms. Migratory arthritis and tenosynovitis of knees, hands, wrists, feet, and ankles were noticed during clinical examination. Synovial fluid leukocyte count was 12,000/ml and culture was sterile. The patient has been successfully treated with injection ceftriaxone 1 g Q24 hours for 7 days. What was the diagnosis in this setting?

Disseminated gonococcal infection

Arthritis due to Pseudomonas aeruginosa

Sexually Transmitted Enteric Infections: High-Yield Internal Medicine Lessons

STEIs Overview - Gut Instincts Gone Wrong

Definition: Infections of the gastrointestinal tract transmitted through sexual contact, distinct from classical STIs.
Transmission Modes: Primarily oral-anal (anilingus), digital-rectal contact; less commonly, fomites.
High-Risk Populations: Predominantly men who have sex with men (MSM).
Pathogen Spectrum: Includes:
- Bacteria: Shigella spp., Salmonella spp., Campylobacter spp., E. coli (EHEC, EPEC).
- Viruses: Hepatitis A, Hepatitis E, Norovirus, Rotavirus.
- Protozoa: Giardia lamblia, Entamoeba histolytica, Cryptosporidium spp.

⭐ Many enteric STIs present with symptoms of proctitis (rectal inflammation) or proctocolitis (inflammation of rectum and colon).

Bacterial Pathogens - Proctitis Perpetrators

Presumptive Rx (acute proctitis): Ceftriaxone 500mg IM (1g if ≥150kg) + Doxycycline 100mg BD x 7d.

Pathogen	Sx	Dx	Rx
Neisseria gonorrhoeae	Rectal pain, pus, tenesmus	Gram-stain (GNDC), NAATs	Ceftriaxone 500mg IM + Doxy 100mg BDx7d
Chlamydia trachomatis (non-LGV)	Mild/asymptomatic; discharge	NAATs	Doxy 100mg BDx7d or Azithro 1g PO x1
Chlamydia trachomatis (LGV)	Severe proctocolitis, bloody discharge, ulcers	NAATs, Serology	Doxy 100mg BDx21d
Treponema pallidum	Anal chancre, proctitis	Dark-field, Serology	Benzathine Pen G 2.4MU IM x1
Shigella spp.	Bloody diarrhea, fever, tenesmus	Stool culture, NAATs	Cipro 500mg BDx3-5d or Azithro 500mg ODx3d (check resistance)
Salmonella spp.	Diarrhea (±blood), fever	Stool culture, NAATs	Supportive; Cipro if severe
Campylobacter spp.	Bloody diarrhea, fever	Stool culture (special media), NAATs	Azithro 500mg ODx3d

⭐ LGV proctocolitis mimics IBD; can cause strictures/fistulae.

Protozoal & Viral Agents - Microscopic Marauders

Protozoal Agents:
- Entamoeba histolytica (Amoebiasis):
  - Bloody diarrhea, abdominal pain, liver abscess.
  - Stool microscopy (cysts/RBC-laden trophozoites), Ag tests, PCR.
  - Metronidazole/Tinidazole, then luminal agent (Paromomycin).
- Giardia lamblia (Giardiasis):
  - Foul, fatty stools (steatorrhea), bloating. 📌 'Gay Bowel Syndrome' (historical), fatty stools.
  - Stool microscopy (cysts/trophozoites), Ag tests.
  - Metronidazole, Tinidazole, Nitazoxanide.
- Cryptosporidium spp. (Cryptosporidiosis):
  - Watery diarrhea (severe in immunocompromised).
  - Modified acid-fast (oocysts), Ag tests.
  - Nitazoxanide (immunocompetent); HAART (HIV).
Viral Agents:
- Herpes Simplex Virus (HSV) Proctitis:
  - Severe anorectal pain, tenesmus, vesicles.
  - Viral culture, PCR from lesions.
  - Acyclovir, Valacyclovir.
  ⭐ HSV proctitis: severe anorectal pain, tenesmus, radicular pain (Elsberg syndrome).
- Cytomegalovirus (CMV) Colitis:
  - Bloody diarrhea, pain (immunocompromised, CD4 < 50).
  - Colonoscopy + biopsy (owl's eye), PCR.
  - Ganciclovir, Valganciclovir.
- Hepatitis A Virus (HAV):
  - Jaundice, fever, nausea. Fecal-oral (sexual).
  - Anti-HAV IgM.
  - Supportive. Vaccination.

Clinical Approach & Mgmt - Gut Check & Game Plan

Clinical Syndromes:
- Proctitis: Anorectal pain, tenesmus, discharge, bleeding. Affects distal 10-12 cm rectum.
- Proctocolitis: Proctitis symptoms + bloody/mucoid diarrhea, abdominal pain, ±fever. Involves rectum & colon.
- Enteritis: Watery diarrhea, nausea, vomiting, abdominal cramps. Primarily small bowel.
Diagnostic & Management Pathway:
Management Principles: Aim for etiologic diagnosis. Syndromic approach for severe cases or diagnostic delay. Partner notification and treatment are vital.
Prevention: Counsel on safe sex (condoms), hygiene. Offer Hepatitis A/B vaccination. PrEP for HIV indirectly reduces risk.

⭐ A thorough sexual history is crucial as it guides the differential diagnosis and testing for enteric STIs.

High‑Yield Points - ⚡ Biggest Takeaways

Sexually transmitted enteric infections are prevalent in MSM (Men who have Sex with Men).

Common presentations include proctitis, proctocolitis, and enteritis.

Key pathogens: Shigella, Salmonella, Campylobacter, LGV (C. trachomatis), N. gonorrhoeae, HSV, HPV, E. histolytica, Giardia.

LGV proctocolitis mimics IBD with tenesmus and bloody discharge; biopsy shows granulomas.

Gonococcal proctitis is often asymptomatic; diagnosed by NAAT.

Syphilitic proctitis may show anal chancres or condylomata lata.

Amebiasis and Giardiasis are common protozoal infections, treated with metronidazole.

Unlock the full lesson and continue reading

Signup to continue reading this lesson and unlimited access questions, flashcards, AI notes, and more

Scan to download app

UNLOCK FREE ACCESS