Impact of Revised Infectious Diseases Society of America and Society for Healthcare Epidemiology of America Clinical Practice Guidelines on the Treatment of Clostridium difficile Infections in the United States

Is there a role for intestinal sporobiota in the antimicrobial resistance crisis?

Antimicrobial resistance (AMR) is a complex issue requiring specific, multi-sectoral measures to slow its spread. When people are exposed to antimicrobial agents, it can cause resistant bacteria to increase. This means that the use, misuse, and excessive use of antimicrobial agents exert selective pressure on bacteria, which can lead to the development of "silent" reservoirs of antimicrobial resistance genes. These genes can later be mobilized into pathogenic bacteria and contribute to the spread of AMR. Many socioeconomic and environmental factors influence the transmission and dissemination of resistance genes, such as the quality of healthcare systems, water sanitation, hygiene infrastructure, and pollution. The sporobiota is an essential part of the gut microbiota that plays a role in maintaining gut homeostasis. However, because spores are highly transmissible and can spread easily, they can be a vector for AMR. The sporobiota resistome, particularly the mobile resistome, is important for tracking, managing, and limiting the spread of antimicrobial resistance genes among pathogenic and commensal bacterial species.

Health Hazard Associated with the Presence of Clostridium Bacteria in Food Products

Clostridium bacteria were already known to Hippocrates many years before Christ. The name of the Clostridium species is owed to the Polish microbiologist, Adam Prażmowski. It is now known that these Clostridium bacteria are widespread in the natural environment, and their presence in food products is a threat to human health and life. According to European Food Safety Authority (EFSA) reports, every year, there are poisonings or deaths due to ingestion of bacterial toxins, including those of the Clostridium spp. The strengthening of consumer health awareness has increased interest in consuming products with minimal processing in recent years, which has led to a need to develop new techniques to ensure the safety of microbiological food, including elimination of bacteria from the Clostridium genera. On the other hand, the high biochemical activity of Clostridium bacteria allows them to be used in the chemical, pharmaceutical, and medical industries. Awareness of microbiological food safety is very important for our health. Unfortunately, in 2022, an increase in infections with Clostridium bacteria found in food was recorded. Knowledge about food contamination should thus be widely disseminated.

Reduced Vancomycin Susceptibility in Clostridioides difficile Is Associated With Lower Rates of Initial Cure and Sustained Clinical Response

BACKGROUND

Epidemiologic studies have shown decreasing vancomycin susceptibility among clinical Clostridioides difficile isolates, but the impact on patient outcomes is unknown. We hypothesized that reduced vancomycin susceptibility would be associated with decreased rates of sustained clinical response (SCR).

METHODS

This multicenter cohort study included adults with C. difficile infection (CDI) treated with oral vancomycin between 2016 and 2021. Clostridioides difficile isolates underwent agar dilution vancomycin susceptibility testing, ribotyping, and Sanger sequencing of the vancomycin resistance vanR gene. Reduced susceptibility was defined as vancomycin minimum inhibitory concentration (MIC) >2 μg/mL. The primary outcome was 30-day SCR; secondary outcomes were 14-day initial cure, 30-day recurrence, and 30-day mortality. Exploratory analysis assessed the association between the VanR Thr115Ala polymorphism, susceptibility, and outcomes.

RESULTS

A high proportion (34% [102/300]) of C. difficile isolates exhibited reduced vancomycin susceptibility (range, 0.5-16 μg/mL; MIC50/90 = 2/4 μg/mL). Ribotype 027 accounted for the highest proportion (77.4% [41/53]) of isolates with reduced vancomycin susceptibility. Overall, 83% (249) of patients achieved 30-day SCR. Reduced vancomycin susceptibility was associated with lower rates of 30-day SCR (76% [78/102]) than vancomycin-susceptible strains (86% [171/198]; P = .031). A significantly lower rate of 14-day initial cure was also observed among individuals infected with strains with reduced vancomycin susceptibility (89% vs 96%; P = .04). Reduced susceptibility remained an independent predictor of 30-day SCR in multivariable modeling (odds ratio, 0.52 [95% confidence interval, .28-.97]; P = .04).

CONCLUSIONS

Reduced vancomycin susceptibility in C. difficile was associated with decreased odds of 30-day SCR and lower 14-day initial cure rates in the studied patient cohort.

Host-defense piscidin peptides as antibiotic adjuvants against Clostridioides difficile

The spore-forming intestinal pathogen Clostridioides difficile causes multidrug resistant infection with a high rate of recurrence after treatment. Piscidins 1 (p1) and 3 (p3), cationic host defense peptides with micromolar cytotoxicity against C. difficile, sensitize C. difficile to clinically relevant antibiotics tested at sublethal concentrations. Both peptides bind to Cu2+ using an amino terminal copper and nickel binding motif. Here, we investigate the two peptides in the apo and holo states as antibiotic adjuvants against an epidemic strain of C. difficile. We find that the presence of the peptides leads to lower doses of metronidazole, vancomycin, and fidaxomicin to kill C. difficile. The activity of metronidazole, which targets DNA, is enhanced by a factor of 32 when combined with p3, previously shown to bind and condense DNA. Conversely, the activity of vancomycin, which acts at bacterial cell walls, is enhanced 64-fold when combined with membrane-active p1-Cu2+. As shown through microscopy monitoring the permeabilization of membranes of C. difficile cells and vesicle mimics of their membranes, the adjuvant effect of p1 and p3 in the apo and holo states is consistent with a mechanism of action where the peptides enable greater antibiotic penetration through the cell membrane to increase their bioavailability. The variations in effects obtained with the different forms of the peptides reveal that while all piscidins generally sensitize C. difficile to antibiotics, co-treatments can be optimized in accordance with the underlying mechanism of action of the peptides and antibiotics. Overall, this study highlights the potential of antimicrobial peptides as antibiotic adjuvants to increase the lethality of currently approved antibiotic dosages, reducing the risk of incomplete treatments and ensuing drug resistance.

Fecal Pharmacokinetics and Gut Microbiome Effects of Oral Omadacycline Versus Vancomycin in Healthy Volunteers

BACKGROUND

Clostridioides difficile infection (CDI) is a common healthcare-associated infection with limited treatment options. Omadacycline, an aminomethylcycline tetracycline, has potent in vitro activity against C difficile and a low propensity to cause CDI in clinical trials. We aimed to assess fecal pharmacokinetics and gut microbiome effects of oral omadacycline compared to oral vancomycin in healthy adults.

METHODS

This was a phase 1, nonblinded, randomized clinical trial conducted in healthy volunteers aged 18-40 years. Subjects received a 10-day course of omadacycline or vancomycin. Stool samples were collected at baseline, daily during therapy, and at follow-up visits. Omadacycline and vancomycin stool concentrations were assessed, and microbiome changes were compared.

RESULTS

Sixteen healthy volunteers with a mean age of 26 (standard deviation [SD], 5) years were enrolled; 62.5% were male, and participants' mean body mass index was 23.5 (SD, 4.0) kg/m2. Omadacycline was well tolerated with no safety signal differences between the 2 antibiotics. A rapid initial increase in fecal concentrations of omadacycline was observed compared to vancomycin, with maximum concentrations achieved within 48 hours. A significant difference in alpha diversity was observed following therapy in both the omadacycline and vancomycin groups (P < .05). Bacterial abundance and beta diversity analysis showed differing microbiome changes in subjects who received omadacycline versus vancomycin.

CONCLUSIONS

Subjects given omadacycline had high fecal concentrations with a distinct microbiome profile compared to vancomycin.

CLINICAL TRIALS REGISTRATION

NCT06030219.

European Practice for CDI Treatment

Clostridioides difficile infection (CDI) remains a significant cause of morbidity and mortality worldwide. Historically, two antibiotics (metronidazole and vancomycin) and a recent third (fidaxomicin) have been used for CDI treatment; convincing data are now available showing that metronidazole is the least efficacious agent. The European Society of Clinical Microbiology and Infectious Diseases (ESCMID) management guidance for CDI were updated in 2021. This guidance document outlines the treatment options for a variety of CDI clinical scenarios and for non-antimicrobial management (e.g., faecal microbiota transplantation, FMT). One of the main changes is that metronidazole is no longer recommended as first-line CDI treatment. Rather, fidaxomicin is preferred on the basis of reduced recurrence rates with vancomycin as an acceptable alternative. Recommended options for recurrent CDI now include bezlotoxumab as well as FMT.A 2017 survey of 20 European countries highlighted variation internationally in CDI management strategies. A variety of restrictions were in place in 65% countries prior to use of new anti-CDI treatments, including committee/infection specialist approval or economic review/restrictions. This survey was repeated in November 2022 to assess the current landscape of CDI management practices in Europe. Of 64 respondents from 17 countries, national CDI guidelines existed in 14 countries, and 11 have already/plan to incorporate the ESCMID 2021 CDI guidance, though implementation has not been surveyed in 6. Vancomycin is the most commonly used first-line agent for the treatment of CDI (n = 42, 66%), followed by fidaxomicin (n = 30, 47%). Six (9%) respondents use metronidazole as first-line agent for CDI treatment, whereas 22 (34%) only in selected low-risk patient groups. Fidaxomicin is more likely to be used in high-risk patient groups. Availability of anti-CDI therapy influenced prescribing in six respondents (9%). Approval pre-prescription was required before vancomycin (n = 3, 5%), fidaxomicin (n = 10, 6%), bezlotoxumab (n = 11, 17%) and FMT (n = 10, 6%). Implementation of CDI guidelines is rarely audited.Novel anti-CDI agents are being evaluated; it is not yet clear what will be the roles of these agents. The treatment of recurrent CDI is particularly troublesome, and several different live biotherapeutics are being developed, in addition to FMT.

Decoding a cryptic mechanism of metronidazole resistance among globally disseminated fluoroquinolone-resistant Clostridioides difficile

Severe outbreaks and deaths have been linked to the emergence and global spread of fluoroquinolone-resistant Clostridioides difficile over the past two decades. At the same time, metronidazole, a nitro-containing antibiotic, has shown decreasing clinical efficacy in treating C. difficile infection (CDI). Most metronidazole-resistant C. difficile exhibit an unusual resistance phenotype that can only be detected in susceptibility tests using molecularly intact heme. Here, we describe the mechanism underlying this trait. We find that most metronidazole-resistant C. difficile strains carry a T-to-G mutation (which we term PnimB^G) in the promoter of gene nimB, resulting in constitutive transcription. Silencing or deleting nimB eliminates metronidazole resistance. NimB is related to Nim proteins that are known to confer resistance to nitroimidazoles. We show that NimB is a heme-dependent flavin enzyme that degrades nitroimidazoles to amines lacking antimicrobial activity. Furthermore, occurrence of the PnimB^G mutation is associated with a Thr82Ile substitution in DNA gyrase that confers fluoroquinolone resistance in epidemic strains. Our findings suggest that the pandemic of fluoroquinolone-resistant C. difficile occurring over the past few decades has also been characterized by widespread resistance to metronidazole.

Microbiome-Related and Infection Control Approaches to Primary and Secondary Prevention of Clostridioides difficile Infections

Clostridioides difficile infections (CDIs) have decreased in the past years, but since 2021, some hospitals have reported an increase in CDI rates. CDI remains a global concern and has been identified as an urgent threat to healthcare. Although multiple treatment options are available, prevention strategies are more limited. As CDI is an opportunistic infection that arises after the normally protective microbiome has been disrupted, preventive measures aimed at restoring the microbiome have been tested. Our aim is to update the present knowledge on these various preventive strategies published in the past five years (2018-2023) to guide clinicians and healthcare systems on how to best prevent CDI. A literature search was conducted using databases (PubMed, Google Scholar, and clinicaltrials.gov) for phase 2-3 clinical trials for the primary or secondary prevention of CDI and microbiome and probiotics. As the main factor for Clostridium difficile infections is the disruption of the normally protective intestinal microbiome, strategies aimed at restoring the microbiome seem most rational. Some strains of probiotics, the use of fecal microbial therapy, and live biotherapeutic products offer promise to fill this niche; although, more large randomized controlled trials are needed that document the shifts in the microbiome population.

Evaluation of fidaxomicin use in community hospitals after a clinical guideline change at a large health system and opportunities for stewardship

After updating our health system's Clostridioides difficile treatment protocols in 2018, we reviewed 104 unique hospital encounters involving fidaxomicin at 10 community hospitals. Half (50%) of regimens were adherent to our guidelines, with infectious diseases (ID) providers were frequently nonadherent. Antimicrobial stewardship programs are important for facilitating best practices, even among ID specialists.

European survey on the current surveillance practices, management guidelines, treatment pathways and heterogeneity of testing of Clostridioides difficile, 2018-2019: results from The Combatting Bacterial Resistance in Europe CDI (COMBACTE-CDI)

BACKGROUND

Awareness and compliance with international guidelines for diagnosis and clinical management of Clostridioides difficile infection (CDI) are unknown.

AIM

To compare the awareness and compliance with the recommended strategies for diagnosis and clinical management of CDI across Europe in 2018-2019.

METHODS

Hospital sites and their associated community practices across 12 European countries completed an online survey in 2018-2019, to report on their practices in terms of surveillance, prevention, diagnosis, and treatment of CDI. Responses were collected from 105 hospitals and 39 community general practitioners (GPs).

FINDINGS

Hospital sites of 11 countries reported participation in national surveillance schemes compared with six countries for international schemes. The European Society of Clinical Microbiology and Infectious Diseases (ESCMID)-recommended CDI testing methodologies were used by 82% (86/105) of hospitals, however countries reporting the highest incidence of CDI used non-recommended tests. Over 75% (80/105) of hospitals were aware of the most recent European CDI treatment guidelines at the time of this survey compared with only 26% (10/39) of surveyed GPs. However, up to 15% (16/105) of hospitals reported using the non-recommended metronidazole for recurrent CDI cases, sites in countries with lower awareness of CDI treatment guidelines. Only 37% (39/105) of hospitals adopted contact isolation precautions in case of suspected CDI.

CONCLUSION

Good awareness of guidelines for the management of CDI was observed across the surveyed European hospital sites. However, low compliance with diagnostic testing guidelines, infection control measures for suspected CDI, and insufficient awareness of treatment guidelines continued to be reported in some countries.

Validating agent-based simulation model of hospital-associated Clostridioides difficile infection using primary hospital data

As agent-based models (ABMs) are increasingly used for modeling infectious diseases, model validation is becoming more crucial. In this study, we present an alternate approach to validating hospital ABMs that focuses on replicating hospital-specific conditions and proposes a new metric for validating the social-environmental network structure of ABMs. We adapted an established ABM representing Clostridioides difficile infection (CDI) spread in a generic hospital to a 426-bed Midwestern academic hospital. We incorporated hospital-specific layout, agent behaviors, and input parameters estimated from primary hospital data into the model, referred to as H-ABM. We compared the predicted CDI rate against the observed rate from 2013-2018. We used colonization pressure, a measure of nearby infectious agents, to validate the socio-environmental agent networks in the ABM. Finally, we conducted additional experiments to compare the performance of individual infection control interventions in the H-ABM and the generic model. We find that the H-ABM is able to replicate CDI trends during 2013-2018, including a roughly 46% drop during a period of greater infection control investment. High CDI burden in socio-environmental networks was associated with a significantly increased risk of C. difficile colonization or infection (Risk ratio: 1.37; 95% CI: [1.17, 1.59]). Finally, we found that several high-impact infection control interventions have diminished impact in the H-ABM. This study presents an alternate approach to validation of ABMs when large-scale calibration is not appropriate for specific settings and proposes a new metric for validating socio-environmental network structure of ABMs. Our findings also demonstrate the utility of hospital-specific modeling.

Clinical and Economic Outcomes After Implementation of a Fidaxomicin Treatment Optimization and Access Pathway at a US Hospital System

INTRODUCTION

This study aimed to evaluate the clinical and economic outcomes of implementing a Clostridiodes difficile infection (CDI) Treatment Optimization and Access Pathway (treatment pathway) directing first-line use of fidaxomicin for CDI.

METHODS

This was a retrospective, quasi-experimental study of adult patients with CDI using Electronic Health Record data from a single center. The primary intervention was implementation of a treatment pathway directing first-line use of fidaxomicin for patients with first/second CDI episode and at high risk of recurrence. The primary clinical outcome was CDI recurrence within 30 days of completing therapy in patients achieving clinical cure. Secondary clinical outcomes included clinical cure and sustained response evaluated at 90 days after completion of CDI treatment. Economic outcomes included costs associated with hospital stay at index admission and 30- and 90-day readmission. Differences between the pre- and post-implementation cohorts were assessed for baseline characteristics, CDI treatment utilization, clinical outcomes, and economic outcomes. The budget impact was calculated for the pre- vs. post-implementation cohorts, each normalized to 100 patients.

RESULTS

Post- vs. pre-implementation, 30-day recurrence (6.4% vs. 18.0%., p = 0.001), 90-day recurrence (14.9% vs. 27.1%, p = 0.009), and 30-day (4.6% vs. 12.7%, p = 0.007) and 90-day CDI-related readmissions (8.5% vs. 18.9%, p = 0.007) were lower. The clinical cure (94.1% vs. 84.4%, p = 0.002) and 90-day sustained response rates were higher (73.3% vs. 55.9%, p < 0.001). Median total costs were also lower in the post- vs. pre-implementation cohorts at index admission ($11,934.64 vs. $14,523.27, p = 0.048), and 30-day ($7685.82 vs. $12,424.44, p = 0.102) and 90-day CDI-related readmission episodes ($8246.69 vs. $12,729.57, p = 0.042). The budget impact analyses of 100 patients post- vs. pre-implementation found saving of $222,895 overall and $9432 per CDI-readmission avoided.

CONCLUSIONS

Implementation of the CDI treatment pathway was associated with better clinical outcomes and hospital cost savings. The findings help validate real-world value of fidaxomicin for CDI disease management.

Detection of Plasmid-Mediated Resistance to Metronidazole in Clostridioides difficile from River Water

Clostridioides difficile is one of the most important human pathogens. The identification of its possible sources is important for the understanding of C. difficile infection (CDI) epidemiology. A total of 16 water samples from wastewater and surface water in South Moravia in the Czech Republic and 82 samples of fish and gulls were collected between May and July 2019. C. difficile isolates were cultured by direct plating and after enrichment on chromogenic media. Susceptibility testing to eight antimicrobials was performed by Etest. C. difficile isolates were characterized by ribotyping, multilocus sequence typing, multilocus tandem repeats analysis, and toxin gene detection. Samples from fish and gulls were C. difficile negative; a total of 15 C. difficile isolates from 8 out of 16 water samples were cultured (6 out of 14 surface water samples yielded 6 isolates, and 2 out of 2 wastewater samples yielded 9 isolates). Direct plating was culture positive in 6 out of 16 samples (12 isolates), and enrichment culture was positive in an additional 2 out of 16 samples (3 isolates). Twelve different ribotyping profiles and 14 sequence types of clades 1, 4, and 5 were identified. Five isolates did not carry genes for toxins, and eight isolates carried genes for toxins A and B; the remaining two isolates (RT078) carried the genes for toxins A, B, and binary. All C. difficile isolates were susceptible to amoxicillin, moxifloxacin, tetracycline, and vancomycin and resistant to ciprofloxacin. A high level of erythromycin resistance (>256 mg/L) was detected in eight isolates. Clindamycin resistance was found in 14 isolates, 6 of which showed a high level of resistance (>256 mg/L) and carried ermB. Surprisingly, one isolate (RT010, ST15) showed resistance to metronidazole (12 mg/L) with the presence of the plasmid pCD-METRO. In conclusion, a diverse spectrum of C. difficile strains was found in wastewater and surface water. A recently discovered plasmid-bound resistance to metronidazole was detected in C. difficile from the surface water sample.

IMPORTANCE The combination of direct plating and culture after enrichment was used in order to gain a spectrum of C. difficile ribotypes present in the water samples. Toxigenic C. difficile ribotypes detected in surface water and in wastewater treatment plants overlapped with those derived from patients with CDI and/or animals. Importantly, a recently discovered plasmid-mediated resistance to metronidazole, a drug used for the treatment of CDI, was detected in C. difficile from river water.

Current Status of Opportunistic Infection in Inflammatory Bowel Disease Patients in Asia: A Questionnaire-Based Multicenter Study

Background/Aims

Opportunistic infection in inflammatory bowel disease (IBD) has become a serious problem. However, its status of doctors' opinions and test equipment in hospitals are unclear. The aim of the study was to investigate these issues to improve the prognosis of IBD patients.

Methods

This retrospective, multicenter study was conducted by 83 investigators who were members of the Asian Organization for Crohn's and Colitis. Data on opportunistic infection were collected from hospital databases between January 2017 and December 2017. The survey consisted of 11 items.

Results

Most physicians appreciated the diagnostic value of tissue cytomegalovirus (CMV) DNA, accounting for 86.1% of members in China, 37.5% in Japan, 52.9% in South Korea, and 66.7% in Southeast Asia. Only 83.1% of hospitals had the ability to test for CMV immunohistochemistry in Asia. Hepatitis B surface antigen (HBsAg) screening was recommended by all members. However, only 66.7% in China, 70.6% in South Korea, and 66.7% in Southeast Asia agreed to routinely vaccinate IBD patients when HBsAg tested negative. Most members preferred metronidazole (74.7%) as the first choice for patients with Clostridium difficile infection. However, the proportion of stool C. difficile toxin test was lower in China than in other areas (75.0% in China vs 95.8% in Japan and 100% in South Korea and Southeast Asia, p<0.05).

Conclusions

Opportunistic infection from CMV, hepatitis B virus, and C. difficile should be of high concern for IBD patients. More efforts are needed, such as understanding consensus in clinical practice and improving testing facilities in hospitals.

Genetic Mechanisms of Vancomycin Resistance in Clostridioides difficile: A Systematic Review

Antimicrobial resistance to treatments for Clostridioides difficile infection (CDI) poses a significant threat to global health. C. difficile is widely thought to be susceptible to oral vancomycin, which is increasingly the mainstay of CDI treatment. However, clinical labs do not conduct C. difficile susceptibility testing, presenting a challenge to detecting the emergence and impact of resistance. In this systematic review, we describe gene determinants and associated clinical and laboratory mechanisms of vancomycin resistance in C. difficile, including drug-binding site alterations, efflux pumps, RNA polymerase mutations, and biofilm formation. Additional research is needed to further characterize these mechanisms and understand their clinical impact.

Which is the Preferred Regimen for Non-Severe Clostridioides difficile Infection in Korea, Vancomycin or Metronidazole?

The emergence of hypervirulent Clostridioides difficile strains has decreased the efficacy of metronidazole in the treatment of C. difficile infection (CDI). Therefore, revised guidelines no longer recommend the use of metronidazole as a first-line regimen for CDI and restrict its use for non-severe CDI, only when vancomycin and fidaxomicin are unavailable. In Korea, an epidemic caused by a hypervirulent C. difficile strain or the emergence of metronidazole resistant C. difficile strains have not been reported. This review article aims to compare the treatment outcomes and adverse effects of vancomycin and metronidazole and discuss the validity of the guidelines of various agencies, which restrict the use of metronidazole, for Korean patients. There are no substantial adverse effects of metronidazole, and its clinical outcomes against non-severe CDI are similar to those of vancomycin. Based on these findings, we recommend that the use of metronidazole for the treatment of non-severe CDI is still an appropriate option in Korea.

Gut associated metabolites and their roles in Clostridioides difficile pathogenesis

The nosocomial pathogen Clostridioides difficile is a burden to the healthcare system. Gut microbiome disruption, most commonly by broad-spectrum antibiotic treatment, is well established to generate a state that is susceptible to CDI. A variety of metabolites produced by the host and/or gut microbiota have been shown to interact with C. difficile. Certain bile acids promote/inhibit germination while other cholesterol-derived compounds and amino acids used in the Stickland metabolic pathway affect growth and CDI colonization. Short chain fatty acids maintain intestinal barrier integrity and a myriad of other metabolic compounds are used as nutritional sources or used by C. difficile to inhibit or outcompete other bacteria in the gut. As the move toward non-antibiotic CDI treatment takes place, a deeper understanding of interactions between C. difficile and the host's gut microbiome and metabolites becomes more relevant.

Surgical antimicrobial prophylaxis in open reduction internal fixation procedures at a metropolitan hospital in Australia: a retrospective audit

Background

Open reduction internal fixation (ORIF) of closed fractures is a required indication for surgical antimicrobial prophylaxis (SAP). Guidelines contain recommendations on how best to prescribe SAP, however, adherence to SAP guidelines remains suboptimal. The Australian Therapeutic Guidelines: Antibiotic v16 (updated April 2019) advocates for single dose prophylaxis for ORIF procedures. There is a paucity of information on how SAP is prescribed for ORIF of closed fractures in Australian hospitals. The aim of this study was to identify prescribing practice and to evaluate guideline adherence pre- and post-guideline update.

Methods

A retrospective audit was conducted for patients undergoing an ORIF of closed fractures at a metropolitan teaching hospital in a 6-month period during 2018 (pre-guideline update) and 2019 (post-guideline update). Data were collected on prescribing practice (perioperative antibiotics prescribed, dose, time and route of administration and duration of prophylaxis) and compared to SAP recommendations in Therapeutic Guidelines: Antibiotic v15 (2018) and v16 (2019). Descriptive statistics and Chi square tests were used to report categorical variables. Binary logistic regression was used to identify factors associated with guideline adherence. A p-value < 0.05 was deemed statistically significant.

Results

Data were collected for a total of 390 patients (n = 185, 2018; n = 205, 2019). Cefazolin was the most commonly prescribed antibiotic as per guideline recommendations, with variable, yet appropriate doses observed across the two audit periods. While 78.3% of patients received SAP for the correct duration in 2018, only 20.4% of patients received single dose prophylaxis in 2019. Overall adherence to guidelines was 63.2% in the 2018, and 18.0% in the 2019 audit periods respectively. Patient age was significantly associated with an increase in overall guideline adherence, while lower limb fractures, an American Society of Anesthesiologists (ASA) score of 3 and emergency admissions were associated with decreased overall adherence to SAP guidelines.

Conclusion

Adherence to guidelines was greater with v15 (2018) compared with v16 (2019). Patient factors, including limb fracture site and ASA score, had little impact on guideline adherence. Further research is required to understand what influences guideline adherence in the orthopaedic setting.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12893-021-01398-7.

Medicare Prescription Plans Limit Access to Recommended Drugs for Clostridioides difficile Infection

We analyzed June 2021 Medicare Advantage/Part D enrollment and formulary data. Oral vancomycin and fidaxomicin, frontline Clostridioides difficile treatments, were on formulary for 100% (42,314,676/42,314,676) and 84.1% (35,598,385/42,314,676) of enrollees, respectively. However, they were broadly accessible (formulary, unrestricted, Tier 1 or 2) to only 14.4% (6,104,348/42,314,676) and 1.1% (483,004/42,314,676), respectively.

Exploratory Cost-Effectiveness Analysis for Treatment of Methicillin-Resistant Staphylococcus aureus Bloodstream Infections: Is Linezolid or Daptomycin Favored Over Vancomycin?

BACKGROUND AND OBJECTIVE

Methicillin-resistant Staphylococcus aureus bloodstream infections (MRSAB) cause significant mortality, and often require extended antibiotic therapy. Vancomycin, the most common initial MRSAB treatment, carries significant monitoring burden and nephrotoxicity risks. Our objective was to compare the cost-effectiveness of vancomycin and other antibiotic regimens against MRSAB.

METHODS

We estimated the cost-effectiveness of intravenous antibiotics (vancomycin, daptomycin, linezolid, ceftaroline/daptomycin) for Veterans Health Administration patients with MRSAB using an exploratory decision-tree model. Primary effectiveness outcome was composite of microbiological failure at 7 days and adverse drug event (ADE)-related discontinuation after at least 7 days.

RESULTS

In base-case analyses, intravenous linezolid was the least expensive regimen at 4 and 6 weeks. Daptomycin was more expensive and more effective than linezolid, with an incremental cost-effectiveness ratio (ICER) of ~$13,000 (4 weeks) per composite failure avoided. With 6 weeks of treatment, daptomycin was more expensive and more effective than vancomycin (ICER ~$21,000 per composite failure avoided). Vancomycin and ceftaroline/daptomycin were dominated strategies at both 4 and 6 weeks. In one-way sensitivity analyses, vancomycin was favored when its microbiological failure risk was less than 20.1% (base-case: 27.2%), assuming a willingness to pay (WTP) threshold of $40,000/composite treatment failure avoided. In two-way sensitivity analyses, intravenous linezolid was favored if linezolid microbiological failure and ADE-related discontinuation rates were < 22.5% and < 17.3%, respectively. Daptomycin, vancomycin, and linezolid were favored in 50%, 31%, and 17% of 4-week probabilistic iterations, respectively, at $40,000 WTP.

CONCLUSION

Daptomycin is likely less expensive and more effective than vancomycin or other initial regimens for MRSAB. More data are needed on the safety of linezolid against MRSAB.

The Integrity of Heme Is Essential for Reproducible Detection of Metronidazole-Resistant Clostridioides difficile by Agar Dilution Susceptibility Tests

Metronidazole resistance in clinical Clostridioides difficile is often described as unstable, since resistant strains reportedly appear susceptible following freezer storage or brief passage. This has presented a conundrum for adopting susceptibility testing to accurately evaluate the connection between metronidazole resistance and decreased clinical efficacy of metronidazole in patients with C. difficile infections (CDIs). We discovered that supplementation of microbiological media with the metalloporphyrin heme is crucial for detection of metronidazole-resistant C. difficile using the agar dilution susceptibility testing method. Known metronidazole-resistant strains appeared susceptible to metronidazole in media lacking heme. Similarly, these resistant strains exhibited increased susceptibility to metronidazole when tested on heme-containing agars that were exposed to room light for more than 1 day, likely due to heme photodecomposition. In parallel experiments, resistance was reproducibly detected when heme-containing agars were either prepared and used on the same day or protected from light and then used on subsequent days. Notably, heme did not influence the susceptibilities of drug-susceptible strains that were of the same ribotype as the resistant strains. These findings firmly show that the consistent detection of metronidazole-resistant C. difficile is dependent upon heme and its protection from light. Studies are warranted to determine the extent to which this heme-associated metronidazole-resistant phenotype affects the clinical efficacy of metronidazole in CDI and the underlying genetic and biochemical mechanisms.

Budget Impact Analysis of Fidaxomicin Versus Vancomycin for the Treatment of Clostridioides difficile Infection in the United States

INTRODUCTION

Fidaxomicin is as effective as vancomycin in treating Clostridioides difficile infection (CDI) but more effective at preventing recurrence. However, because fidaxomicin is more costly than vancomycin, its overall value in managing CDI is not well understood. This study assessed the budget impact of introducing fidaxomicin versus vancomycin for the treatment of adults with CDI from a hospital perspective in the US.

METHODS

A cohort-based decision analytic model was developed over a 1-year horizon. A hospital with 10,000 annual hospitalizations was simulated. The model considered two adult populations: patients with no prior CDI episode and patients with one prior CDI episode. Two scenarios were assessed per population: 15% fidaxomicin/85% vancomycin use and 100% vancomycin use. Model inputs were obtained from published sources and expert opinion. Model outcomes included cost, payment, and revenue at the hospital level, per treated CDI patient, and per admitted patient. Budget impact was calculated as the difference in revenue between scenarios. One-way sensitivity analyses tested the effects of varying model inputs on the budget impact.

RESULTS

In patients with no prior CDI episode, treatment with fidaxomicin resulted in potential savings over 1 year of $1105 at the hospital level, $14 per treated CDI patient, and $0.11 per admitted patient. In patients with one prior CDI episode, fidaxomicin use was associated with potential savings over 1 year of $1150 at the hospital level, $74 per treated CDI patient, and $0.12 per admitted patient. Savings were driven by a reduced rate of CDI recurrence with fidaxomicin treatment and uptake of fidaxomicin. Sensitivity analyses indicated savings when inputs were varied in most scenarios.

CONCLUSION

Budgetary savings can be achieved with fidaxomicin due to reduced CDI recurrence as a result of a superior sustained clinical response. Our results support considering the broader benefits of fidaxomicin, beyond its cost, when making formulary inclusion decisions.

Haem is crucial for medium-dependent metronidazole resistance in clinical isolates of Clostridioides difficile

Background

Until recently, metronidazole was the first-line treatment for Clostridioides difficile infection and it is still commonly used. Though resistance has been reported due to the plasmid pCD-METRO, this does not explain all cases.

Objectives

To identify factors that contribute to plasmid-independent metronidazole resistance of C. difficile.

Methods

Here, we investigate resistance to metronidazole in a collection of clinical isolates of C. difficile using a combination of antimicrobial susceptibility testing on different solid agar media and WGS of selected isolates.

Results

We find that nearly all isolates demonstrate a haem-dependent increase in the MIC of metronidazole, which in some cases leads to isolates qualifying as resistant (MIC >2 mg/L). Moreover, we find an SNP in the haem-responsive gene hsmA, which defines a metronidazole-resistant lineage of PCR ribotype 010/MLST ST15 isolates that also includes pCD-METRO-containing strains.

Conclusions

Our data demonstrate that haem is crucial for medium-dependent metronidazole resistance in C. difficile.

Changes in treatment of community-onset Clostridioides difficile infection after release of updated guidelines, Atlanta, Georgia, 2018

Updated Clostridioides difficile infection (CDI) guidelines published in 2018 recommend vancomycin as first-line treatment. Of 833 community-onset CDI cases in metropolitan Atlanta, Georgia in 2018, over half did not receive first-line treatment, although guideline adherence increased over the year. Second-line treatment was more common in patients treated in ambulatory settings.

Evaluation of Connecticut medical providers' concordance with 2017 IDSA/SHEA Clostridioides difficile treatment guidelines in New Haven County, 2018-2019

OBJECTIVES

To assess Connecticut medical providers' concordance (2018-2019) with the 2017 Clostridioides difficile infection (CDI) treatment update by the Infectious Disease Society of America (IDSA) and the Society for Healthcare Epidemiology of America (SHEA). The effect of guideline concordance on CDI recurrence risk was also assessed.

DESIGN

Prospective, population-based study.

SETTING

New Haven County, Connecticut, from January 1, 2017, to December 31, 2019.

PATIENTS

CDI incident case (no positive tests in the prior 8 weeks), not limited by care setting.

METHODS

Using data from the Emerging Infections Program's CDI surveillance, severity and concordance were defined. Presence of megacolon and/or ileus defined fulminant disease; absence defined nonsevere/severe disease. Using 2017 treatment as baseline, 2018-2019 concordance was defined as receiving the recommended first-line antibiotic (ie, vancomycin or fidaxomicin for adult patients, vancomycin or metronidazole for pediatric patients) for exactly 10 days. For all analyses, significance was P < .05.

RESULTS

Among 990 cases, concordance increased from 24.8% in 2018 to 37.0% in 2019. First-line antibiotic concordance increased from 61.2% in 2018 to 79.9% in 2019. Recurrence risk was significantly associated with patients aged ≥65 years and was highest for those aged 75-84 years, but this factor was not significantly associated with concordance.

CONCLUSIONS

From 2018 through 2019, CDI treatment in New Haven County increasingly was concordant with the 2017 treatment update but remained low in 2019. Although concordance with treatment guidelines did not affect recurrence risk, close attention should be paid by medical providers to patients aged ≥65 years, specifically those aged 75-84 years because they are at an increased risk for recurrence.