Gastrointestinal complications of HIV infection

Acute HIV infection, also called the acute retroviral syndrome, is the symptomatic viremic phase in the days to weeks after HIV acquisition, presenting with fever, fatigue, myalgia, rash, and pharyngitis at a time when antibody testing may still be negative. Diagnosis requires an HIV RNA viral load, and antiretroviral therapy should begin as soon as the patient is ready, regardless of CD4 count.

Antiretroviral therapy (ART) combines three or more drugs from at least two classes to suppress HIV replication. First-line therapy is bictegravir/emtricitabine/tenofovir alafenamide or dolutegravir-based triple therapy, started as soon as the patient is ready regardless of CD4 count, and continued for life to prevent AIDS and transmission.

Candida species cause a spectrum from mucocutaneous disease (thrush, esophagitis, vulvovaginal candidiasis, intertrigo) to candidemia and invasive candidiasis, the fourth most common cause of bloodstream infection with 30-40% mortality. Diagnosis of invasive disease requires recognizing risk factors because only 40-60% of infected patients have positive blood cultures, and initial therapy is an echinocandin with prompt catheter removal.

Cytomegalovirus is a ubiquitous herpesvirus that is usually asymptomatic or causes a heterophile-negative mononucleosis-like illness in healthy hosts, but reactivates to cause retinitis, colitis, pneumonitis, or encephalitis in transplant recipients and patients with AIDS; treatment is systemic ganciclovir or valganciclovir, with foscarnet and cidofovir reserved for resistance or intolerance.

Herpes simplex virus type 1 or 2 establishes lifelong latency in sensory ganglia after mucocutaneous infection, causing painful vesicular-to-ulcerative outbreaks of the mouth or genitals with intermittent asymptomatic shedding; diagnosis is by NAAT of an ulcer swab and treatment is oral nucleoside analogues, escalating to intravenous acyclovir for encephalitis, severe mucocutaneous disease, or disseminated infection in immunosuppressed hosts.

Kaposi sarcoma is a human herpesvirus 8-associated vascular malignancy that presents as violaceous macules, papules, plaques, or tumors of the skin, mouth, gastrointestinal tract, or lungs, most often in HIV-associated, transplant-related, or classic elderly disease. Diagnosis is confirmed by biopsy. Every patient with HIV-associated Kaposi sarcoma starts or optimizes antiretroviral therapy, with liposomal doxorubicin 20 mg/m2 intravenously every 21 days added for extensive or visceral disease.

Non-Hodgkin lymphoma is a heterogeneous group of B-cell (about 85%) and T-cell lymphoid malignancies that spread noncontiguously and often involve extranodal sites, ranging from indolent follicular lymphoma to aggressive diffuse large B-cell lymphoma to highly aggressive Burkitt lymphoma. Diagnosis requires excisional or core biopsy with flow cytometry and cytogenetics, Ann Arbor staging with PET-CT, and treatment is subtype-specific, from observation to R-CHOP to intensive Burkitt regimens with aggressive tumor lysis and CNS prophylaxis.

Primary sclerosing cholangitis is an autoimmune fibroinflammatory disease of the large bile ducts, occurring mostly in young men and associated with inflammatory bowel disease, chiefly ulcerative colitis, in 80 to 90% of cases. MRCP showing multifocal strictures and dilations confirms the diagnosis, no drug alters progression, and management centers on endoscopic dilation of dominant strictures, surveillance for cholangiocarcinoma and colorectal cancer, and liver transplantation for advanced disease.

Giardiasis is infection of the proximal small bowel with the protozoan Giardia lamblia (duodenalis), acquired from cysts in contaminated fresh water or food, causing malabsorptive, foul-smelling, greasy diarrhea with bloating and weight loss over weeks. Diagnosis rests on a stool antigen or nucleic acid test, and treatment is a short course of tinidazole, metronidazole, or nitazoxanide.

Clostridioides difficile infection is toxin-mediated colitis that follows disruption of normal colonic flora, most often by antibiotics, and ranges from watery diarrhea to fulminant colitis with shock, ileus, or megacolon. Diagnosis rests on unformed stool testing (NAAT and/or toxin EIA) in a patient with three or more unformed stools in 24 hours, and treatment is chosen by IDSA/SHEA severity grade, oral vancomycin or fidaxomicin for 10 days, escalating to high-dose vancomycin plus IV metronidazole for fulminant disease.

Salmonella infection splits into nontyphoidal disease, a usually self-limited foodborne gastroenteritis that can bacteremically seed bone and joints in sickle cell disease, and typhoidal disease (S. Typhi/Paratyphi), a prolonged travel-associated bacteremic enteric fever with stepwise fever, relative bradycardia, and rose spots. Nontyphoidal disease is diagnosed by stool culture and managed supportively, while enteric fever is diagnosed by blood culture and always treated with antibiotics.

Acalculous cholecystitis is acute gallbladder inflammation without gallstones, driven by ischemia and biliary stasis in critically ill, fasting, or TPN-dependent patients. Ultrasound showing gallbladder wall thickening or pericholecystic fluid without stones supports the diagnosis. Untreated mortality reaches 75 percent, so treatment starts with intravenous antibiotics plus percutaneous cholecystostomy, followed by cholecystectomy once the patient stabilizes.

Dysphagia is difficulty swallowing, and the history alone localizes it to oropharyngeal disease, marked by choking or nasal regurgitation at the start of a swallow, or esophageal disease, marked by food sticking seconds later. Esophageal dysphagia with solids alone points to a mechanical obstruction worked up first with upper endoscopy, while dysphagia for solids and liquids together points to a motility disorder worked up with barium esophagram and manometry.