Treatment of gastrointestinal infections Original paper

What was reviewed?

The review article comprehensively examined antimicrobial therapies used to manage bacterial, protozoal, viral, and fungal infections affecting the gastrointestinal (GI) tract. The review, grounded in clinical and pharmacological data up to December 1999, provided an evidence-based summary of the preferred treatments for both common and rare GI infections. It addressed considerations related to drug selection, resistance trends, immune status of patients, and prophylaxis, highlighting cases with evolving or controversial guidelines. The review also included updates on the efficacy of metronidazole and other agents in treating protozoal infections such as giardiasis and amebiasis.

Who was reviewed?

The review synthesized data from diverse clinical populations, primarily patients with GI infections ranging from self-limiting diarrhea to severe immunocompromised-related pathologies. It included both immunocompetent and immunocompromised hosts, with special attention to vulnerable groups such as transplant recipients, patients with HIV/AIDS, and those undergoing chemotherapy. The article drew from randomized controlled trials, observational studies, and retrospective clinical reports.

What were the most important findings?

The authors established metronidazole as the drug of choice for multiple protozoal infections, including Giardia lamblia, Entamoeba histolytica, and Balantidium coli. In giardiasis, the standard regimen of 250 mg orally three times daily for five days demonstrated up to 95% cure rates. For E. histolytica, metronidazole at 750 mg three times daily for ten days effectively targeted trophozoites in cases of colitis or liver abscess, although it required follow-up with intraluminal agents for cyst eradication. These findings align with metronidazole’s anaerobic and microaerophilic specificity, making it a cornerstone in both acute and chronic protozoal therapy.

From a microbiome perspective, the review confirmed that metronidazole’s potent activity against anaerobes, including Bacteroides, Clostridia, and Lactobacilli, poses a significant risk for microbial imbalance and dysbiosis, especially in prolonged or repeated courses. However, its short-term, targeted use in protozoal infections minimizes this risk when carefully administered. For Clostridium difficile-associated diarrhea (CDAD), metronidazole remained the preferred first-line therapy due to efficacy and its lower risk of promoting vancomycin-resistant organisms. The review also noted metronidazole’s role in combination therapy with other antimicrobials for polymicrobial intra-abdominal infections and its effective oral bioavailability, which supports its widespread use in outpatient settings.

What are the implications of this review?

The review emphasized metronidazole’s critical position in GI infectious disease treatment and encouraged clinicians to exercise precision and restraint in its use to prevent resistance and microbiome disruption. For microbiome-sensitive conditions, metronidazole offers a dual-edged profile-high efficacy with anaerobic pathogens but a substantial impact on beneficial microbial communities. This insight calls for better stewardship, especially given the rising resistance in Giardia and the association of long-term metronidazole use with neurotoxicity. The review highlighted the need for second-line agents and non-antibiotic adjuncts to preserve microbiome health and reduce antimicrobial pressure. Clinicians should view metronidazole as a potent but s