From the FDA Drug Label
The bactericidal action of vancomycin against Staphylococcus aureus and the vegetative cells of Clostridium difficile results primarily from inhibition of cell-wall biosynthesis. Vancomycin has been shown to be active against most isolates of the following microorganisms, both in vitro and in clinical infections [see Indications and Usage (1)]. Gram-positive bacteria: Staphylococcus aureus (including methicillin-resistant isolates) associated with enterocolitis. Anaerobic gram-positive bacteria: Clostridium difficile isolates associated with C. difficile associated bacteria.
A positive Clostridium difficile (C. diff) test with a negative toxin assay may still indicate the presence of C. diff.
- Vancomycin is effective against C. diff isolates.
- The presence of C. diff without toxin detection may still warrant treatment with Vancomycin to prevent potential complications. However, the FDA drug label does not provide explicit guidance on treating C. diff with a negative toxin assay. Given the potential risks associated with C. diff, treatment with Vancomycin may be considered on a case-by-case basis, taking into account the individual patient's clinical presentation and medical history 1.
From the Research
Treatment with Vancomycin is not recommended for patients with a positive Clostridium difficile test but negative toxin assay, as they are likely colonized carriers rather than having active C. difficile infection (CDI) 2. The patient is likely a colonized carrier rather than having active CDI, and Vancomycin should be reserved for cases with positive toxin testing or when there is strong clinical suspicion of CDI despite negative toxin results in a symptomatic patient. Some key points to consider in this scenario include:
- The rationale for withholding treatment in toxin-negative cases is that C. difficile can colonize the gut without causing disease, and unnecessary antibiotic treatment may disrupt the gut microbiome further, potentially increasing the risk of developing true CDI later 3.
- Treating asymptomatic carriers does not reduce transmission risk and contributes to antimicrobial resistance.
- If treatment is deemed necessary based on clinical judgment, oral vancomycin (125 mg four times daily for 10 days) would be the standard first-line therapy, with fidaxomicin as an alternative 4.
- Recent studies have shown that fecal microbiota transplantation is a promising treatment option for recurrent CDI, and may be considered in patients who have failed antibiotic treatment 5.
- New treatment approaches, such as bacteriophages and monoclonal antibodies, are being developed and may offer alternative options for the treatment of CDI in the future 6.