Effective Dosage of Oral Vancomycin in Treatment for Initial Episode of Clostridioides difficile Infection: A Systematic Review and Meta-Analysis

A Rare Case of Chronic Photophobia Associated With Oral Vancomycin Therapy: Exploring the Relationship

Vancomycin is a widely used tricyclic glycopeptide antibiotic for treating various Gram-positive infections, including Clostridium difficile colitis. Although considered generally safe, it has been associated with several side effects. In this case report, we highlight a rare adverse effect in which a patient experienced chronic photophobia following treatment with oral vancomycin. This sheds light upon a potential relationship between oral vancomycin therapy and photophobia, emphasizing the need for increased awareness in clinical practice and urging further investigation into this association.

Ulcerative colitis (K51), adults

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Clostridium difficile in Oncology Patients—Review of Diagnosis and Management in the Indian Setting

Clostridoides (formerly Clostridium) difficile (C. difficile) is a toxin-producing, gram-positive anaerobic bacillus, commonly implicated in antibiotic-associated diarrhea and pseudomembranous colitis. The true burden of C. difficile infection is unclear in India, as it is likely underdiagnosed and underreported. Its incidence is much higher in oncology patients where it can contribute significantly to morbidity and mortality. There are several challenges in the Indian setting, including lack of uniform availability of testing infrastructure, as well as therapy. Oncology patients further present with a unique set of challenges. This article will review the approach to diagnosis and management of C. difficile-associated diarrhea in India, with a focus on oncology patients.

Fecal pharmacokinetics/pharmacodynamics characteristics of fidaxomicin and vancomycin against Clostridioides difficile infection elucidated by in vivo feces-based infectious evaluation models

OBJECTIVES

The pharmacokinetics (PK)/pharmacodynamics (PD; PK/PD) characteristics of fidaxomicin (FDX) and vancomycin (VCM) against Clostridioides difficile infection (CDI) are yet to be elucidated because of the lack of an established PK/PD analysis method for intestinal infections and unabsorbed oral drugs. Here, we developed a feces-based PK/PD analysis method and determined the fecal PK/PD index, with target values of FDX and VCM against CDI.

METHODS

The antimicrobial susceptibility, time-kill curves, and post-antibiotic effects (PAEs) of FDX and VCM against C. difficile were determined in vitro. The optimal fecal PK/PD indices, with target values, were determined from the results of PK and PD studies involving 5-week-old female C57BL/6J mice infected with C. difficile ATCC® 43255. The minimum inhibitory concentration (MIC) breakpoints for C. difficile were estimated based on clinical data concerning fecal antibiotic concentrations in patients with CDI.

RESULTS

FDX and VCM inhibited C. difficile growth via time-dependent antibacterial activity and exerted PAEs. In the CDI mouse model experiments, the changes in C. difficile load and clinical cures (72-hour survival rates and clinical sickness score grading) were most highly correlated with the ratio of area under the fecal drug concentration-time curve to MIC (AUC_0→∞/MIC). The target AUC_0→∞/MIC values of FDX and VCM for 3 log₁₀ reduction in C. difficile load was 13,173 and 8,308, respectively. The MIC breakpoints of FDX and VCM for C. difficile was estimated to be 1.0 and 2.0 μg/mL, respectively.

CONCLUSIONS

The developed in vivo feces-based PK/PD analysis method elucidated the optimal fecal PK/PD index, with target values of FDX and VCM against CDI.

Effect of oral vancomycin dose on outcomes in patients with Clostridioides difficile infection

Clostridioides difficile infection (CDI) is a significant cause of morbidity and mortality. Oral vancomycin is a cornerstone of CDI treatment, but dosing strategies in clinical practice may differ from guideline recommendations. This study aimed to determine differences in outcomes between patients treated with standard (125 mg QID) and high-dose (≥250 mg QID) oral vancomycin. This dual-centre study evaluated adult patients admitted between January 2013 and July 2017. Patients were included in the study if they had a positive C. difficile toxin PCR, symptomatic infection and received ≥48 h of oral vancomycin. Disease severity was characterised using a variety of classifiers, including guideline definitions. The primary outcome was 90-day CDI recurrence; secondary outcomes included clinical failure, in-hospital mortality and 90-day re-admission. Inverse probability of treatment weighting (IPTW) was conducted to balance differences between groups. A total of 535 patients were included; 261 received standard and 274 received high-dose vancomycin. Baseline demographics were similar between groups, except that patients receiving high-dose vancomycin were more likely to have more severe disease and to be admitted to the ICU. Few patients had fulminant disease (14.4%). No significant differences in recurrence (OR, 1.52, 95% CI 0.82-2.84), clinical failure (OR, 0.64, 95% CI 0.328-1.26), mortality (OR, 1.44, 95% CI 0.78-2.66) or re-admission (OR, 1.03, 95% CI 0.70-1.51) were identified between patients receiving standard and high-dose vancomycin in the IPTW analyses. No differences in recurrence, mortality or re-admission were identified between standard and high-dose vancomycin for the treatment of CDI not requiring surgery.

Randomized Controlled Trial of Oral Vancomycin Treatment in Clostridioides difficile-Colonized Patients

Clostridioides difficile infection (CDI) is most commonly diagnosed using nucleic acid amplification tests (NAAT); the low positive predictive value of these assays results in patients colonized with C. difficile unnecessarily receiving CDI treatment antibiotics. The risks and benefits of antibiotic treatment in individuals with such cases are unknown. Fecal samples of NAAT-positive, toxin enzyme immunoassay (EIA)-negative patients were collected before, during, and after randomization to vancomycin (n = 8) or placebo (n = 7). C. difficile and antibiotic-resistant organisms (AROs) were selectively cultured from fecal and environmental samples. Shotgun metagenomics and comparative isolate genomics were used to understand the impact of oral vancomycin on the microbiome and environmental contamination. Overall, 80% of placebo patients and 71% of vancomycin patients were colonized with C. difficile posttreatment. One person randomized to placebo subsequently received treatment for CDI. In the vancomycin-treated group, beta-diversity (P = 0.0059) and macrolide-lincosamide-streptogramin (MLS) resistance genes (P = 0.037) increased after treatment; C. difficile and vancomycin-resistant enterococci (VRE) environmental contamination was found in 53% of patients and 26% of patients, respectively. We found that vancomycin alters the gut microbiota, does not permanently clear C. difficile, and is associated with VRE colonization/environmental contamination. (This study has been registered at ClinicalTrials.gov under registration no. NCT03388268.)IMPORTANCE A gold standard diagnostic for Clostridioides difficile infection (CDI) does not exist. An area of controversy is how to manage patients whose stool tests positive by nucleic acid amplification tests but negative by toxin enzyme immunoassay. Existing data suggest most of these patients do not have CDI, but most are treated with oral vancomycin. Potential benefits to treatment include a decreased risk for adverse outcomes if the patient does have CDI and the potential to decrease C. difficile shedding/transmission. However, oral vancomycin perturbs the intestinal microbiota and promotes antibiotic-resistant organism colonization/transmission. We conducted a double-blinded randomized controlled trial to assess the risk-benefit of oral vancomycin treatment in this population. Oral vancomycin did not result in long-term clearance of C. difficile, perturbed the microbiota, and was associated with colonization/shedding of vancomycin-resistant enterococci. This work underscores the need to better understand this population of patients in the context of C. difficile/ARO-related outcomes and transmission.

Optimal vancomycin dose in the treatment of Clostridium difficile infection, antimicrobial stewardship initiative

C. difficile infections (CDI) are increasingly recognized as a leading cause of infectious diarrhea, with increasing morbidity and mortality. Treatment primarily centers around oral vancomycin treatment. A wide range of dosing regimens exist in clinical practice, with little evidence to help distinguish the therapeutic benefit between them. This is a retrospective cohort study conducted at an academic medical center that enrolled adult patients admitted with CDI. The primary outcome was a composite of complete or partial cure at the end of treatment and was assessed using a test of equivalency with a 20% equivalency limit. Subjects were divided into low dose (125 mg) or high dose (250 mg or 500 mg) of oral vancomycin dosed every 6 hours. Overall, 78 patients were included who received low dose vancomycin and 33 who received high dose. Generally, the two groups were similar, except the low dose group had significantly more leukocytosis and less ICU admission or hypotension compared to the high dose group. Equivalency between the two treatment groups was demonstrated (Absolute Risk Difference -0.022, 90% confidence interval: -0.13 to 0.18, p = 0.03). A stepwise logistic regression identified gender, baseline albumin, and ICU admission as significant predictors of the chance for complete or partial cure. No differences between groups for the secondary outcomes of 90-day readmission/recurrence, 30-day all-cause mortality, or time to resolution of diarrhea were demonstrated. Low dose oral vancomycin was demonstrated to result in equivalent outcomes compared to high dose vancomycin for the treatment of CDI.