Evaluation of diarrhea in HIV-infected patients

Conduite à tenir devant une diarrhée aiguë. Étiologies

Les diarrhées aiguës constituent un problème de santé publique du fait de leur grande fréquence. Leur origine est presque toujours infectieuse et leur évolution spontanément résolutive, le plus souvent en moins de 3 jours. Seul 1 % des diarrhées nécessite d'emblée des explorations complémentaires, notamment des examens de selles, car leur présentation clinique évoque une colite aiguë sous-jacente (selles sanglantes, douleurs abdominales circonscrites), du fait d'un terrain fragile sous-jacent avec un risque immédiat pour le malade, ou d'un contexte particulier (séjour sous les tropiques…). Ces examens de selles doivent être orientés afin de guider le biologiste et améliorer la rentabilité des prélèvements, qui s'avère sinon très faible et coûteuse à l'échelle d'une population. Une antibiothérapie empirique basée essentiellement sur les fluoroquinolones est ensuite licite dans ces cas sélectionnés, en attendant les résultats des examens. Ces explorations sont aussi justifiées lorsque la diarrhée persiste au-delà de 3 jours. Enfin, lorsque l'épisode se prolonge au-delà de 5 jours, avec des prélèvements de selles négatifs, un avis spécialisé est nécessaire. Ainsi, seule une petite proportion de ces diarrhées aiguës va nécessiter une endoscopie, permettant de parler ainsi de colite ou de rectocolite. Au plan thérapeutique, la réhydratation précoce chez l'enfant reste d'actualité car elle a prouvé son efficacité en termes de mortalité depuis plus de deux décennies, principalement dans les pays en voie de développement.

Differences in Rates of Diarrhea in Patients with Human Immunodeficiency Virus Receiving Lopinavir-Ritonavir or Nelfinavir

STUDY OBJECTIVE

To determine and compare rates of diarrhea in patients receiving an antiretroviral regimen containing lopinavir-ritonavir versus nelfinavir and in patients who received these drugs sequentially.

DESIGN

Retrospective cohort analysis.

SETTING

Hospital-based human immunodeficiency virus (HIV) clinic.

PATIENTS

Four hundred one participants in the HIV Atlanta VA Cohort Study who were prescribed lopinavir-ritonavir or nelfinavir from 1996-2002.

MEASUREMENTS AND MAIN RESULTS

Chart review identified episodes of diarrhea that potentially were associated with an antiretroviral agent. Data collected included antidiarrheal agents dispensed, baseline viral load and CD4+ cell counts, demographic variables, and previous therapy Diarrhea associated with an antiretroviral regimen occurred in 175 (49%) of 354 patients receiving nelfinavir and 17 (17%) of 99 patients receiving lopinavir-ritonavir (p < 0.001). Treatment for the diarrhea occurred in 118 (33%) of 354 patients receiving nelfinavir and 9 (9%) of 99 receiving lopinavir-ritonavir (p < 0.001). Patients in the lopinavir-ritonavir group were more likely to have received highly active antiretroviral therapy and azithromycin than patients receiving nelfinavir, and they had lower baseline CD4+ cell counts (p < or = 0.01 for each comparison). The average number of months/person-year of diarrhea treatment was 2.0 for the nelfinavir group and 0.13 for the lopinavir-ritonavir group. Of the 10 antiretroviral-naive patients who received lopinavir-ritonavir, none needed treatment for diarrhea, whereas 78 (36%) of 217 antiretroviral-naive patients who received nelfinavir required treatment for diarrhea. Of the 52 patients who had been taking nelfinavir and were switched to lopinavir-ritonavir, they were more likely to start antidiarrheal treatment while taking nelfinavir (14 [27%]) than while receiving lopinavir-ritonavir (3 [6%]) (p = 0.004).

CONCLUSIONS

Patients receiving lopinavir-ritonavir were significantly less likely to have diarrhea or to require treatment for diarrhea than patients receiving nelfinavir. The same results occurred when the drugs were given to the same patients sequentially (nelfinavir followed by lopinavir-ritonavir). The diarrhea associated with lopinavir-ritonavir was less frequent, less severe, and shorter in duration than diarrhea associated with nelfinavir.

Infectious diarrhea in human immunodeficiency virus

Chronic HIV-associated diarrhea is currently a field in flux. Improved noninvasive diagnostic tests, improved pathogen-specific regimens, and better empiric therapies may change some of the assumptions used to select algorithms for diagnostic evaluation and management. Any shift in the cause of diarrhea from pathogen-associated to idiopathic or a reduction in the overall incidence of diarrhea would have considerable impact. It is unclear how significant the problem of pathogen relapse in previous responders will become. Existing studies reviewed in this article show that the high diagnostic yield of endoscopy when stool tests are negative, coupled with significantly better outcomes when pathogens are identified, support the current practice of routine endoscopic evaluation. There currently are scant data on the economic impact of HIV-associated diarrhea as it relates to pathogen-specific and empiric therapy in the era of protease inhibitors. Such data would be integral to future evaluation of the impact of diagnostic and therapeutic strategies.

Small Intestinal Infections

The differential diagnosis of small intestinal infections is broad, making the identification and management of these disorders challenging. The majority of cases of acute diarrhea are self-limited and do not require diagnostic evaluation or treatment. Most patients do not require specific therapy, and treatment should focus on fluid and electrolyte replacement. In patients with severe, persistent, or chronic diarrhea, a careful medical history and routine stool testing are helpful in determining the cause. Pathogen-specific therapy should be given in patients in whom a pathogen is identified. In those without an identifiable pathogen, antidiarrheal agents are helpful in reducing the number of bowel movements and preventing further dehydration. Endoscopy may be helpful in patients with severe diarrhea and a negative stool evaluation, particularly in HIV-infected patients with chronic diarrhea. Surgery has a limited role in the management of small intestinal infections, but may be lifesaving in patients with intestinal perforation or small bowel obstruction.

Gastrointestinal manifestations of HIV infection

Since the beginning of the AIDS pandemic, gastrointestinal (GI) problems have been among the most common features of the disease. Despite the introduction of highly active antiretroviral therapy (HAART) in 1995 and 1996, most HIV-infected patients continue to have GI complications. The clinician must be able to diagnose and treat the opportunistic gastrointestinal infections and neoplasms that occur in the advanced AIDS patient, as well as the treatment-induced symptoms and non-HIV-related GI disorders that predominate in early HIV disease. This review addresses the GI manifestations of HIV, with particular emphasis on new developments in the era of highly effective therapy.

Infectious diarrhea

Infectious diarrhea is an extremely common illness that affects millions of Americans annually. For most patients, the illness is a self-limited one. Its major risk is dehydration. However, for some patients, diarrhea can lead to severe dehydration or be associated with bacteremia and metastatic infection. Patients with these conditions require prompt treatment. A large number of organisms have been associated with diarrhea in humans, and most laboratories routinely screen for Salmonella, Shigella, and Campylobacter. Other bacteria, parasites, and viruses account for a significant percentage of diarrhea cases and frequently go undetected. This article summarizes many of these pathogens and describes the settings in which they can be acquired. Food distribution networks have made the delivery of previously rare foods to remote areas a commonplace occurrence; this has also led to new challenges in the diagnosis and prevention of food-borne illnesses. Outbreaks of diarrhea now frequently extend across many states. The identification of a rare strain of a bacterial pathogen or changes in the isolation rate of common pathogens may be early clues to the cause of such an ongoing outbreak. Most enteric pathogens cause disease by either stimulating the secretion of fluids at the level of the small bowel or by irritating and invading the colon. Organisms that cause disease by the latter mechanism have the potential to invade the blood stream and spread to other parts of the body, including the bones and the central nervous system. Several organisms have been associated with specific postinfectious syndromes that are responsible for additional morbidity and mortality. The antibiotic resistance of bacterial pathogens has been increasing, and this has a limiting effect on the empiric treatment choices available for suspected bacterial diarrhea. Careful attention to local sensitivity patterns and appropriate testing of the patient's isolate are among the important factors that lead to successful treatment decisions.