Severe and refractory Clostridium difficile infection successfully treated with tigecycline and metronidazole

Clostridium butyricum enhances colonization resistance against Clostridioides difficile by metabolic and immune modulation

Clostridioides difficile infection (CDI) represents the leading cause of nosocomial diarrhea worldwide and is associated with gut dysbiosis and intestinal damage. Clostridium butyricum MIYAIRI 588 (CBM 588) contributes significantly to reduce epithelial damage. However, the impacts of CBM 588 on antibacterial therapy for CDI are not clear. Here we show that CBM 588 enhanced the antibacterial activity of fidaxomicin against C. difficile and negatively modulated gut succinate levels to prevent C. difficile proliferation and downregulate tumor necrosis factor-α (TNF-α) producing macrophages in the colon lumina propria (cLP), resulting in a significant decrease in colon epithelial damage. Additionally, CBM 588 upregulated T cell-dependent pathogen specific immunoglobulin A (IgA) via interleukin (IL)-17A producing CD4⁺ cells and plasma B cells in the cLP, and Th17 cells in the cLP enhanced the gut epithelial barrier function. IL-17A and succinic acid modulations with CBM 588 enhance gut colonization resistance to C. difficile and protect the colon tissue from CDI.

Genomic islands mediate environmental adaptation and the spread of antibiotic resistance in multiresistant Enterococci - evidence from genomic sequences

Background

Genomic islands (GIs) play an important role in the chromosome diversity of Enterococcus. In the current study, we aimed to investigate the spread of GIs between Enterococcus strains and their correlation with antibiotic resistance genes (ARGs). Bitsliced Genomic Signature Indexes (BIGSI) were used to screen the NCBI Sequence Read Archive (SRA) for multiple resistant Enterococcus. A total of 37 pairs of raw reads were screened from 457,000 whole-genome sequences (WGS) in the SRA database, which come from 37 Enterococci distributed in eight countries. These raw reads were assembled for the prediction and analysis of GIs, ARGs, plasmids and prophages.

Results

The results showed that GIs were universal in Enterococcus, with an average of 3.2 GIs in each strain. Network analysis showed that frequent genetic information exchanges mediated by GIs occurred between Enterococcus strains. Seven antibiotic-resistant genomic islands (ARGIs) were found to carry one to three ARGs, mdtG, tetM, dfrG, lnuG, and fexA, in six strains. These ARGIs were involved in the spread of antibiotic resistance in 45.9% of the 37 strains, although there was no significant positive correlation between the frequency of GI exchanges and the number of ARGs each strain harboured (r = 0. 287, p = 0.085). After comprehensively analysing the genome data, we found that partial GIs were associated with multiple mobile genetic elements (transposons, integrons, prophages and plasmids) and had potential natural transformation characteristics.

Conclusions

All of these results based on genomic sequencing suggest that GIs might mediate the acquisition of some ARGs and might be involved in the high genome plasticity of Enterococcus through transformation, transduction and conjugation, thus providing a fitness advantage for Enterococcus hosts under complex environmental factors.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12866-021-02114-4.

The impact of Clostridium butyricum MIYAIRI 588 on the murine gut microbiome and colonic tissue

BACKGROUND

Clostridium butyricum MIYAIRI 588 (CBM 588) is a probiotic bacterium that is used as an anti-diarrheal medicine in Japan. However, the impact of this probiotic on the gut microbiome has not been fully elucidated, especially, when used with antimicrobials.

MATERIAL AND METHODS

In an in vivo study, CBM 588 monotherapy, clindamycin monotherapy, CBM 588 and clindamycin (combination therapy), or normal saline (control) was orally administered to mice for 4 days, and fecal samples were collected for 18 days to enumerate C. butyricum. We also extracted DNA from these fecal samples for metagenomics analysis by amplification of the V3-V4 region of the bacterial 16S rRNA gene and MiSeq Illumina sequencing. In addition, the concentrations of some short chain fatty acids were assessed in the fecal samples. A histological analysis was also conducted.

RESULTS

On day 4 (the last treatment day), there was no difference in the total counts of C. butyricum between the CBM 588 monotherapy and combination therapy groups (5.21 ± 0.78 vs. 5.13 ± 0.45 log₁₀ cfu/g, p = 0.86). Clindamycin treatment resulted in dramatic increases in the phylum Firmicutes, especially Enterobacteriaceae, Clostridiaceae, Lactobacillus, and Enterococcus, compared with the other groups during the treatment period. CBM 588 treatment modified the bacterial community composition at lower phylogenetic levels. Some bacterial taxa, such as Bifidobacterium, Coprococcus, and Bacteroides, were significantly increased in the combination therapy group when compared with the other groups. In the metabolic analysis, CBM 588 enhanced lactic acid production. It also enhanced the efficiency of lactic acid use for the production of butyric acid. Only the clindamycin monotherapy group showed abnormal colon tissue, with superficial epithelial necrosis and the presence of inflammatory cells.

CONCLUSION

CBM 588 treatment modulated the gut microbiota composition under dysbiosis due to the use of an antimicrobial with strong activity against anaerobes and significantly reduced epithelial damage.

The outcome of patients with severe and severe-complicated Clostridium difficile infection treated with tigecycline combination therapy: a retrospective observational study

BACKGROUND

Tigecycline is a third-line therapy for severe Clostridium difficile infection (CDI) in Australasian guidelines. Differences in strain types make it difficult to extrapolate international tigecycline efficacy data with combination or monotherapy to Australian practice, where experience is limited.

AIM

To evaluate the efficacy and adverse effects associated with tigecycline combination therapy for severe and severe-complicated CDI in an Australian healthcare setting.

METHODS

This was a retrospective observational study at a metropolitan university-affiliated hospital. All patients between February 2013 and October 2016 treated with adjunctive intravenous tigecycline for >48 h for severe or severe-complicated CDI were included. Tigecycline was given in addition to oral vancomycin ± intravenous metronidazole. The primary outcome was all-cause mortality at 30 days from start of tigecycline combination therapy. Secondary outcomes included clinical cure, colectomy, adverse events and recurrence rates.

RESULTS

Thirteen patients with median age of 61 years had severe (n = 9) or severe-complicated (n = 4) CDI at tigecycline commencement. In 92% of patients, tigecycline started within 48 h after in-hospital CDI treatment, for median duration of 9 days. All-cause mortality at 30 days was 8% with no mortality in severe CDI and 25% (1/4) in patients with severe-complicated fulminant CDI, comparing favourably with historical rates of 9-38% and 30-80% in similar respective groups. Clinical cure was achieved in 77% of cases. There were no colectomies and one attributable tigecycline adverse reaction.

CONCLUSIONS

Tigecycline appears safe and effective as a part of combination therapy in severe CDI, and may be given earlier and for shorter durations than in current guidelines.

Novel Antimicrobials for the Treatment of Clostridium difficile Infection

The current picture of Clostridium difficile infection (CDI) is alarming with a mortality rate ranging between 3% and 15% and a CDI recurrence rate ranging from 12% to 40%. Despite the great efforts made over the past 10 years to face the CDI burden, there are still gray areas in our knowledge on CDI management. The traditional anti-CDI antimicrobials are not always adequate in addressing the current needs in CDI management. The aim of our review is to give an update on novel antimicrobials for the treatment of CDI, considering the currently available evidences on their efficacy, safety, molecular mechanism of action, and their probability to be successfully introduced into the clinical practice in the near future. We identified, through a PubMed search, 16 novel antimicrobial molecules under study for CDI treatment: cadazolid, surotomycin, ridinilazole, LFF571, ramoplanin, CRS3123, fusidic acid, nitazoxanide, rifampin, rifaximin, tigecycline, auranofin, NVB302, thuricin CD, lacticin 3147, and acyldepsipeptide antimicrobials. In comparison with the traditional anti-CDI antimicrobial treatment, some of the novel antimicrobials reviewed in this study offer several advantages, i.e., the favorable pharmacokinetic and pharmacodynamic profile, the narrow-spectrum activity against CD that implicates a low impact on the gut microbiota composition, the inhibitory activity on CD sporulation and toxins production. Among these novel antimicrobials, the most active compounds in reducing spore production are cadazolid, ridinilazole, CRS3123, ramoplanin and, potentially, the acyldepsipeptide antimicrobials. These antimicrobials may potentially reduce CD environment spread and persistence, thus reducing CDI healthcare-associated acquisition. However, some of them, i.e., surotomycin, fusidic acid, etc., will not be available due to lack of superiority versus standard of treatment. The most CD narrow-spectrum novel antimicrobials that allow to preserve microbiota integrity are cadazolid, ridinilazole, auranofin, and thuricin CD. In conclusion, the novel antimicrobial molecules under development for CDI have promising key features and advancements in comparison to the traditional anti-CDI antimicrobials. In the near future, some of these new molecules might be effective alternatives to fight CDI.

Clostridium difficile infection in the elderly: an update on management

The burden of Clostridium difficile infection (CDI) is profound and growing. CDI now represents a common cause of health care–associated diarrhea, and is associated with significant morbidity, mortality, and health care costs. CDI disproportionally affects the elderly, possibly explained by the following risk factors: age-related impairment of the immune system, increasing antibiotic utilization, and frequent health care exposure. In the USA, recent epidemiological studies estimate that two out of every three health care–associated CDIs occur in patients 65 years or older. Additionally, the elderly are at higher risk for recurrent CDI. Existing therapeutic options include metronidazole, oral vancomycin, and fidaxomicin. Choice of agent depends on disease severity, history of recurrence, and, increasingly, the drug cost. Bezlotoxumab, a recently approved monoclonal antibody targeting C. difficile toxin B, offers an exciting advancement into immunologic therapies. Similarly, fecal microbiota transplantation is gaining popularity as an effective option mainly for recurrent CDI. The challenge of decreasing CDI burden in the elderly involves adopting preventative strategies, optimizing initial treatment, and decreasing the risk of recurrence. Expanded strategies are certainly needed to improve outcomes in this high-risk population. This review considers available data from prospective and retrospective studies as well as case reports to illustrate the merits and gaps in care related to the management of CDI in the elderly.

Intravenous Tigecycline Facilitates Cure of Severe Clostridium difficile Infection (CDI) After Failure of Standard Therapy: A Case Report and Literature Review of Tigecycline Use in CDI

Standard treatment for severe Clostridium difficile infection (CDI) is oral vancomycin with metronidazole. After failure of this standard regimen, treatment becomes challenging. A young woman treated for septic shock developed CDI. Standard treatment failed and she was ineligible for fecal transplant. Addition of tigecycline to her regimen resulted in cure.

Recurrent Clostridium difficile infection: From colonization to cure

Clostridium difficile infection (CDI) is increasingly prevalent, dangerous and challenging to prevent and manage. Despite intense national and international attention the incidence of primary and of recurrent CDI (PCDI and RCDI, respectively) have risen rapidly throughout the past decade. Of major concern is the increase in cases of RCDI resulting in substantial morbidity, morality and economic burden. RCDI management remains challenging as there is no uniformly effective therapy, no firm consensus on optimal treatment, and reliable data regarding RCDI-specific treatment options is scant. Novel therapeutic strategies are critically needed to rapidly, accurately, and effectively identify and treat patients with, or at-risk for, RCDI. In this review we consider the factors implicated in the epidemiology, pathogenesis and clinical presentation of RCDI, evaluate current management options for RCDI and explore novel and emerging therapies.

Doxycycline and Tigecycline: Two Friendly Drugs with a Low Association with Clostridium Difficile Infection

Clostridium difficile infection (CDI) is known to be associated with prior exposure to many classes of antibiotics. Standard therapy for CDI (i.e., metronidazole and vancomycin) is associated with high recurrence rates. Although tetracycline derivatives such as tetracycline, doxycycline or tigecycline are not the standard therapeutic choices for CDI, they may serve as an alternative or a component of combination therapy. Previous tetracycline or doxycycline usage had been shown to have less association with CDI development. Tigecycline, a broad-spectrum glycylcycline with potency against many gram-positive or gram-negative pathogens, had been successfully used to treat severe or refractory CDI. The in vitro susceptibility of C. difficile clinical isolates to tigecycline in many studies showed low minimal inhibitory concentrations. Tigecycline can suppress in vitro toxin production in both historical and hypervirulent C. difficile strains and reduce spore production in a dose-dependent manner. Tetracycline compounds such as doxycycline, minocycline, and tigecycline possess anti-inflammatory properties that are independent of their antibiotic activity and may contribute to their therapeutic effect for CDI. Although clinical data are limited, doxycycline is less likely to induce CDI, and tigecycline can be considered one of the therapeutic choices for severe or refractory CDI.

In vitro activity of surotomycin against contemporary clinical isolates of toxigenic Clostridium difficile strains obtained in Spain

OBJECTIVES

Clostridium difficile infection (CDI) is the leading cause of hospital-acquired diarrhoea in developed countries. Metronidazole and vancomycin are the mainstay of treatment, although they are associated with treatment failure and recurrence. Novel agents have emerged to address these shortcomings. We investigated the in vitro activity of a novel agent, surotomycin (formerly CB-183,315), and seven other antimicrobial agents against clinical C. difficile isolates.

METHODS

Antimicrobial susceptibility to surotomycin, fidaxomicin, metronidazole, vancomycin, clindamycin, rifaximin, moxifloxacin and tigecycline was determined for 100 contemporary clinical isolates of C. difficile collected in 2013. MICs were determined by agar dilution according to CLSI procedures. In addition, 10 strains with reduced susceptibility to metronidazole (n = 6) and vancomycin (n = 4) were also tested. Strains were PCR ribotyped.

RESULTS

The MICs of surotomycin for the 100 isolates ranged from ≤0.06 to 2 mg/L, with a geometric mean (GM) of 0.31 mg/L and an MIC50/90 of 0.25/0.5 mg/L. The MIC range of surotomycin was 0.25-1 mg/L (GM = 0.45 mg/L) for isolates with reduced metronidazole susceptibility and 0.125-0.5 mg/L (GM = 0.25 mg/L) for isolates with reduced vancomycin susceptibility. The three most common ribotypes were 001 (31.0%), 014/020 (17.0%) and 078/126 (17.0%). Ribotype 014/020 exhibited the lowest MICs of surotomycin (GM = 0.22 mg/L); the highest MICs were for ribotype 078/126 (GM = 0.72 mg/L).

CONCLUSIONS

Surotomycin exhibited potent in vitro activity against all the isolates tested, including those with elevated metronidazole and vancomycin MICs. The potential role of this agent in the treatment of CDI requires further clinical evaluation.

The potential for emerging therapeutic options for Clostridium difficile infection

Clostridium difficile is mainly a nosocomial pathogen and is a significant cause of antibiotic-associated diarrhea. It is also implicated in the majority of cases of pseudomembranous colitis. Recently, advancements in next generation sequencing technology (NGS) have highlighted the extent of damage to the gut microbiota caused by broad-spectrum antibiotics, often resulting in C. difficile infection (CDI). Currently the treatment of choice for CDI involves the use of metronidazole and vancomycin. However, recurrence and relapse of CDI, even after rounds of metronidazole/vancomycin administration is a problem that must be addressed. The efficacy of alternative antibiotics such as fidaxomicin, rifaximin, nitazoxanide, ramoplanin and tigecycline, as well as faecal microbiota transplantation has been assessed and some have yielded positive outcomes against C. difficile. Some bacteriocins have also shown promising effects against C. difficile in recent years. In light of this, the potential for emerging treatment options and efficacy of anti-C. difficile vaccines are discussed in this review.

Effects of tigecycline and vancomycin administration on established Clostridium difficile infection

The glycylcycline antibiotic tigecycline was approved in 2005 for the treatment of complicated skin and soft tissue infections and complicated intra-abdominal infections. Tigecycline is broadly active against both Gram-negative and Gram-positive microorganisms, including Clostridium difficile. Tigecycline has a low MIC against C. difficile in vitro and thus may represent an alternate treatment for C. difficile infection (CDI). To assess the use of tigecycline for treatment of established CDI, 5- to 8-week-old C57BL/6 mice were colonized with C. difficile strain 630. After C. difficile colonization was established, mice (n = 10 per group) were treated with either a 5-day course of tigecycline (6.25 mg/kg every 12 h subcutaneously) or a 5-day course of vancomycin (0.4 mg/ml in drinking water) and compared to infected, untreated control mice. Mice were evaluated for clinical signs of CDI throughout treatment and at 1 week posttreatment to assess potential for disease development. Immediately following a treatment course, C. difficile was not detectable in the feces of vancomycin-treated mice but remained detectable in feces from tigecycline-treated and untreated control mice. Toxin activity and histopathological inflammation and edema were observed in the ceca and colons of untreated mice; tigecycline- and vancomycin-treated mice did not show such changes directly after treatment. One week after the conclusion of either antibiotic treatment, C. difficile load, toxin activity, and histopathology scores increased in the cecum and colon, indicating that C. difficile-associated disease occurred. In vitro growth studies confirmed that subinhibitory concentrations of tigecycline were able to suppress toxin activity and spore formation of C. difficile, whereas vancomycin did not. Taken together, these data show how tigecycline is able to alter C. difficile pathogenesis in a mouse model of CDI.

Tigecycline for the Treatment of Severe and Severe Complicated Clostridium difficile Infection

Introduction

Clostridium difficile infection (CDI) is a common cause of nosocomial diarrhea. Metronidazole and vancomycin are the primary treatment options for CDI, but increasing rates of antimicrobial resistance and severe, refractory disease have prompted the need for alternative agents. Tigecycline has previously demonstrated favorable in vitro activity against C. difficile isolates, but clinical data on its use in the treatment of CDI are severely lacking. The objective of this study was to describe our experience using tigecycline in the treatment of severe and severe complicated CDI.

Methods

This was a retrospective case series of hospitalized patients with severe and severe complicated CDI who were treated with tigecycline. Disease severity assessments were determined according to current practice guidelines. Diagnosis of toxigenic CDI was confirmed by polymerase chain reaction and patients were excluded if they received tigecycline for <48 h. Data were collected by review of the electronic medical record. The primary outcome was clinical cure. Secondary outcomes were sustained response, hospital mortality, and 28-day all-cause mortality.

Results

A total of 7 cases of severe and complicated CDI were reviewed. Intravenous tigecycline administered as a 100-mg loading dose followed by 50 mg twice daily resulted in clinical cure in 85.7% (n = 6/7) of cases. The majority of patients (n = 4/5) were treated with the novel triple therapy combination of tigecycline, vancomycin, and metronidazole and resulted in clinical cure in 80% (n = 4/5) cases. Sustained response at 28 days was 100% among evaluable cases (n = 5/5). Hospital mortality did not occur in any patients, and 28-day all-cause mortality was 28.6% (n = 2/7).

Conclusion

Tigecycline appears to be a reasonable addition to the therapeutic regimen in the treatment of severe or complicated CDI, including cases that are refractory to standard therapy. A prospective clinical trial confirming these observational findings is warranted.

Electronic supplementary material

The online version of this article (doi:10.1007/s40121-014-0050-x) contains supplementary material, which is available to authorized users.

Tigecycline suppresses toxin A and B production and sporulation in Clostridium difficile

BACKGROUND

Clostridium difficile infection (CDI) is mediated by potent extracellular toxins and is spread largely via bacterial spores. We and others have shown that some antibiotics stimulate C. difficile toxin production in a strain-specific manner; however, the effects of newer anti-C. difficile antibiotics on this process remain to be investigated.

METHODS

The effects of the protein synthesis inhibitor tigecycline on sporulation and toxin A and toxin B production were compared in historical (strain 9689) and hypervirulent BI/NAP1/027 (strain 5325) isolates of C. difficile in vitro.

RESULTS

Tigecycline at 1/4× MIC stimulated an increased and earlier toxin A and/or B gene expression in both the historical and the hypervirulent strains, although a commensurate increase in toxin protein production was observed only in the 9689 strain. In fact, in the hypervirulent 5325 strain, toxin production was dramatically suppressed. By comparison, subinhibitory concentrations of vancomycin and metronidazole also stimulated increased protein toxin production by the historical, but not the hypervirulent, strain. In addition, tigecycline dose-dependently reduced viable spore production by both the 9689 and 5325 strains. Vancomycin treatment also suppressed spore formation in both C. difficile strains; however, metronidazole, while reducing spore formation in the 9689 strain, stimulated a near 2 log increase in spore production by the 5325 isolate.

CONCLUSIONS

In summary, these findings suggest that the treatment of CDI patients with tigecycline could effectively both control disease progression and limit its spread by disrupting sporulation.

Alteration of the murine gastrointestinal microbiota by tigecycline leads to increased susceptibility to Clostridium difficile infection

Antibiotics can play dual roles in Clostridium difficile infection (CDI); antibiotic treatment increases the risk of CDI, and antibiotics are used to treat CDI. The glycylcycline antibiotic tigecycline has broad antimicrobial activity, yet it is rarely associated with the development of CDI, presumably due to its activity against C. difficile. In this study, we investigated how tigecycline treatment affects the structure of the gut microbiota and susceptibility to CDI by treating mice with tigecycline (n = 20) or saline (n = 8) for 10 days. A sequence analysis of the bacterial 16S rRNA gene amplicons was used to monitor changes in the fecal microbiota. A subset of the mice was followed for 5 weeks after the end of treatment. The remaining mice were challenged with C. difficile strain VPI 10463 spores 2 days after the tigecycline treatment ended. Tigecycline treatment resulted in major shifts in the gut microbiota, including large decreases in Bacteroidetes levels and large increases in Proteobacteria levels. Mice with tigecycline-altered microbial communities were susceptible to challenge with C. difficile spores and developed clinical signs of severe CDI. Five weeks after the cessation of tigecycline treatment, the recovery of the bacterial community was incomplete and diversity was lower than in the untreated controls. Antibiotics with intrinsic activity against C. difficile can still alter the microbiota in a way that leads to susceptibility to CDI after discontinuation of the drug. These results indicate that microbiotic dynamics are key in the development of CDI, and a better understanding of these dynamics may lead to better strategies to prevent and treat this disease.

New developments in chemotherapeutic options for Clostridium difficile colitis

PURPOSE OF REVIEW

Clostridium difficile infections (CDIs) are of increasing concern in healthcare due to increasing incidence as well as suboptimal response to standard therapies. This review focuses on current updates in chemotherapeutic treatment options for primary CDI as well as for relapse.

RECENT FINDINGS

Metronidazole and vancomycin remain the standard therapy for mild and severe CDI, respectively. Fidaxomicin was approved for use in CDI by the US Food and Drug Administration in 2011 and new studies have shown a decreased rate of recurrence as compared with vancomycin as well as potential promise for use as a chaser. Rifaximin may be useful in salvage therapy for recurrent CDI as well as for a chaser. Tigecycline, teicoplanin, doxycycline, linezolid, nitazoxanide, amixicile, LFF571, and CB-183 315 have in-vitro activity and are under different stages of study. Monoclonal antitoxin antibodies for prevention of relapse of CDI are currently under evaluation in a phase 3 clinical trial.

SUMMARY

A variety of promising new treatment options for Clostridium difficile are under development, although further studies are necessary to determine the efficacy of these newer treatments for cure and preventing disease relapse.

Prevention of Clostridium difficile spore formation by sub-inhibitory concentrations of tigecycline and piperacillin/tazobactam

BACKGROUND

Sporulation of Clostridium difficile during infection and persistence of spores within the gut could partly explain treatment failures and recurrence. However, the influence of antibiotics on sporulation is unclear. The objective of our study was to evaluate the impact of ciprofloxacin, metronidazole, piperacillin/tazobactam, tigecycline, and vancomycin on C. difficile sporulation in vitro.

METHODS

The reference strains ATCC 9689, 630, VPI 10463, and seven other clinical isolates of C. difficile were used, including three epidemic NAP1/027 isolates. Minimum inhibitory concentrations (MIC) were determined and sporulation was assessed after growth in the absence or presence of ≤0.5x MIC concentrations of each antibiotic.

RESULTS

All strains were sensitive to the antibiotics tested, except ribotype 027 isolates that were resistant to ciprofloxacin (MIC = 128 mg/L). Metronidazole and vancomycin generally did not significantly affect spore production in C. difficile, although vancomycin slightly affected sporulation of a few isolates. Ciprofloxacin inhibited sporulation of ribotype 027 isolates mainly. Interestingly, sub-MIC concentrations of piperacillin/tazobactam reduced spore formation in several isolates. However, the most striking observation was made with tigecycline, with an important reduction of spore formation in most isolates.

CONCLUSIONS

The capacity of C. difficile to sporulate can be significantly affected by certain antibiotics. The reduced sporulation observed with tigecycline and piperacillin/tazobactam might explain why these antibiotics are generally associated with lower risk of C. difficile infections. In addition, the inhibition of sporulation might partly explain the apparent efficacy of tigecycline for treatment of patients with recurrent infection.

Progress in the discovery of treatments for C. difficile infection: A clinical and medicinal chemistry review

Clostridium difficile is an anaerobic, Gram-positive pathogen that causes C. difficile infection, which results in significant morbidity and mortality. The incidence of C. difficile infection in developed countries has become increasingly high due to the emergence of newer epidemic strains, a growing elderly population, extensive use of broad spectrum antibiotics, and limited therapies for this diarrheal disease. Because treatment options currently available for C. difficile infection have some drawbacks, including cost, promotion of resistance, and selectivity problems, new agents are urgently needed to address these challenges. This review article focuses on two parts: the first part summarizes current clinical treatment strategies and agents under clinical development for C. difficile infection; the second part reviews newly reported anti-difficile agents that have been evaluated or reevaluated in the last five years and are in the early stages of drug discovery and development. Antibiotics are divided into natural product inspired and synthetic small molecule compounds that may have the potential to be more efficacious than currently approved treatments. This includes potency, selectivity, reduced cytotoxicity, and novel modes of action to prevent resistance.

Medication risk factors associated with healthcare-associated Clostridium difficile infection: a multilevel model case-control study among 64 US academic medical centres

OBJECTIVES

The main objective of this study was to determine patient- and hospital-level medication risk factors associated with Clostridium difficile infection (CDI) occurrence among patients clustered within hospitals using a multilevel model.

METHODS

Patients with healthcare-associated (HA)-CDI were identified from among 64 academic medical centres in 2009. A frequency match was conducted; for each case, up to two controls were selected, matched on similar pre-infection length of stay and clinical service line. Patient- and hospital-level medication use, including antibacterial and gastric acid-suppressant agents, was assessed using a two-level logistic regression model.

RESULTS

A total of 5967 CDI cases and 8167 controls were included in the analysis. The odds of acquiring HA-CDI increased with the following medications [OR (95% CI)]: anti-methicillin-resistant Staphylococcus aureus agents [1.38 (1.22-1.56)]; third- or fourth-generation cephalosporins [1.75 (1.62-1.89)]; carbapenems [1.60 (1.44-1.79)]; β-lactam/β-lactamase inhibitor combinations [1.49 (1.36-1.64)]; vancomycin [1.73 (1.57-1.89)]; and proton pump inhibitors [1.43 (1.30-1.57)]. The odds of acquiring HA-CDI decreased with the following medications: clindamycin [0.74 (0.63-0.87)]; and macrolides [0.88 (0.77-0.99)]. Controlling for patient-level covariates, no hospital-level medication covariates that we analysed had statistically significant effects on HA-CDI. The odds of acquiring HA-CDI increased with the hospital proportion of patients aged ≥ 65 years [1.01 (1.00-1.02)].

CONCLUSIONS

We found several medications that were associated with the risk of patients developing HA-CDI, including β-lactam/β-lactamase inhibitor combinations, third- or fourth-generation cephalosporins, carbapenems, vancomycin, proton pump inhibitors and anti-methicillin-resistant S. aureus agents. There were no medication effects significant at the hospital level.

Therapy of Clostridium difficile infection: perspectives on a changing paradigm

INTRODUCTION

Clostridium difficile disease (CDI) have increased in frequency and severity over the past decade and are a leading cause of hospital acquired infections, contributing to increased hospital length of stay and costs, as well as associated increased mortality, especially amongst the elderly. Standard therapy has been associated with 20 - 30% relapse rates. Consequently, new CDI therapeutic approaches have emerged.

AREAS COVERED

The role of metronidazole, vancomycin, fidaxomicin, rifaximin, nitizoxanide, tigecycline, fusidic acid, LFF-571, cardazolid, SMT 19969, CamSA and surotomycin were reviewed.

EXPERT OPINION

New IDSA/SHEA guidelines are expected within the next year and may impact selection of primary therapy for CDI. Until then, metronidazole will likely remain as first line therapy because of low cost and despite its inferiority compared to vancomycin. Vancomycin will likely see increasing use, especially as generics become available. Fidaxomicin will emerge as an important therapy for relapse patients and perhaps as initial therapy for patients at greatest risk for relapse, with concomitant antibiotics, multiple comorbidities and renal insufficiency, advanced age and hypoalbuminemia. Biotherapeutics such as fecal microbiota transplantation and non-toxogenic C. difficile prevention will emerge as the preferred therapy in multiple relapse patients and the development of an oral formulation will occur within five years.

Clostridium difficile: a European perspective

Clostridium difficile infection is the leading cause of diarrhoea in the industrialised world. First identified in 1935, our knowledge about the clonal population structure, toxins and PCR ribotypes is still increasing. New PCR ribotypes and sequence types are frequently added. In the last decade hypervirulent strains have emerged and been associated with increased severity of disease, high recurrence and significant mortality. Although previously a primarily hospital- or health-care acquired infection, since the 1990's C. difficile infections that are community-acquired have been increasingly reported. Risk factors include hospitalisation, advancing age and prior antibiotic use. The ubiquitous presence of C. difficile in the environment and asymptomatic intestinal colonisation may be important reservoirs for infection and the changing epidemiology of C. difficile infection. Although surveillance in Europe is now a requirement of the European Commission, reporting is not standardised or mandatory. Here we review the current literature, guidelines on diagnosis and treatment and conclude by highlighting a number of areas where further research would increase our understanding.

Severe anaphylaxis caused by orally administered vancomycin to a patient with Clostridium difficile infection

We report the first case of anaphylaxis to oral vancomycin in a cystic fibrosis patient with severe and relapsing Clostridium difficile infection (CDI) refractory to metronidazole. The patient's colitis has been successfully treated with a combination of intravenous metronidazole and tigecycline.

Refractory Clostridium difficile Infection Successfully Treated with Tigecycline, Rifaximin, and Vancomycin

The occurrence of Clostridium difficile colitis is on the rise and has become more difficult to manage with standard therapy. Thus, the need for alternative treatments is essential. Tigecycline is a glycylcycline antibiotic that has been shown to be effective against C. difficile through several published case reports and in in vitro studies. We present a case of C. difficile colitis that failed to respond to metronidazole and oral vancomycin therapy, but improved on a combination of rifaximin, tigecycline, and vancomycin.

Clostridium difficile infection: an update on epidemiology, risk factors, and therapeutic options

PURPOSE OF REVIEW

The incidence and severity of Clostridium difficile infection (CDI) around the world has increased over the past 20 years due to the emergence of hypervirulent strains, increased use and misuse of antibiotics, and the increase of susceptible at-risk populations. Treatments currently available for CDI are inadequate to impede the increasing spread and virulence of the infection, avoid recurrence in chronic patients or prevent infection in at-risk populations.

RECENT FINDINGS

New and promising evidence has been presented during the past year, focusing on two major points: preservation of gut microflora and optimization of immune response to CDI and toxins.

SUMMARY

The review aims to summarize the most recent evidence available on the epidemiology, risk factors and treatment of CDI. New antibiotics with selected action on C. difficile and limited effect on microflora (fidaxomicin) and donor fecal transplantation seem to have a relevant efficacy in treating CDI and reducing its recurrence. The use of selected monoclonal antibodies directed against C. difficile toxins in addition to standard therapy is a new, promising approach for the treatment of recurrent cases. Vaccination could be an additional weapon against CDI. New robust data are needed before recommendations can be made to abandon current treatment based on vancomycin and metronidazole and move toward new frontiers.

Recurrent refractory Clostridium difficile colitis treated successfully with rifaximin and tigecycline: a case report and review of the literature

Clostridium difficile colitis infection is on the rise and is considerably increasing the duration of hospital stay, as well as healthcare costs. The management of C. difficile colitis has become more challenging with the increasing failure of therapeutic response to metronidazole and oral vancomycin. Tigecycline is a new glycylcycline that has shown in vitro activity against C. difficile. We report herein a case of C. difficile colitis that failed to improve on a combination of metronidazole and oral vancomycin. The patient subsequently developed a surgical abdomen secondary to refractory C. difficile colitis, but was successfully treated with a combination of rifaximin and tigecycline after she refused to undergo surgical treatment.

Clostridium difficile Infection and Inflammatory Bowel Disease: A Review

The incidence of Clostridium difficile infection (CDI) has significantly increased in the last decade in the United States adding to the health care burden of the country. Patients with inflammatory bowel disease (IBD) have a higher prevalence of CDI and worse outcomes. In the past, the traditional risk factors for CDI were exposure to antibiotics and hospitalizations in elderly people. Today, it is not uncommon to diagnose CDI in a pregnant women or young adult who has no risk factors. C. difficile can be detected at the initial presentation of IBD, during a relapse or in asymptomatic carriers. It is important to keep a high index of suspicion for CDI in IBD patients and initiate prompt treatment to minimize complications. We summarize here the changing epidemiology, pathogenesis, risk factors, clinical features, and treatment of CDI in IBD.

Tigecycline for the treatment of severe Clostridium difficile infection

OBJECTIVE

To evaluate the evidence for the use of tigecycline in the treatment of Clostridium difficile infection (CDI).

DATA SOURCES

Searches were performed (2004 to June 2011), using the EMBASE and MEDLINE databases, with the terms tigecycline, Tygacil, Clostridium difficile, C. difficile, Clostridium difficile infection, and CDI.

STUDY SELECTION

Six case reports that described the use of tigecycline for treatment of CDI were included for review. No clinical trials were identified.

DATA SYNTHESIS

In all case reports except 1, tigecycline (alone or in combination with other CDI therapies) was used for the treatment of CDI that was refractory to metronidazole and/or vancomycin. In 6 of the cases, treatment success was reported following initiation of tigecycline therapy; 1 patient died following a complicated hospitalization. The treatment duration with tigecycline was 2-4 weeks. In the cases with successful outcomes, symptoms began to improve within 1 week. None of these patients experienced recurrence during follow-up of various lengths. In vitro studies demonstrated a 90% minimum inhibitory concentration range for tigecycline of 0.016-0.25 mg/L for all C. difficile isolates. Tigecycline exhibited good fecal penetration because of primary biliary excretion of unchanged drug. Up to 59% of the dose is recovered in feces following administration over 4 days in healthy volunteers.

CONCLUSIONS

Case reports have suggested that tigecycline may be successful for treatment of severe or severe complicated CDI, when prior therapy has failed. Data demonstrating tigecycline use as initial therapy for CDI are limited; therefore, this option should be reserved for patients in whom other therapeutic options, including metronidazole and vancomycin, have failed. A randomized controlled trial is needed to assess the safety and efficacy of tigecycline in this patient population and better define the drug's role in the treatment of CDI.

Treatment of refractory and recurrent Clostridium difficile infection

The incidence of Clostridium difficile infection (CDI) has increased since 2000, with greater numbers of severe cases reported, in part due to the emergence of a hypervirulent strain. Initial therapy with metronidazole is still recommended for mild to moderate CDI, but vancomycin is recommended for first-line therapy of severe CDI. Colectomy could be life-saving for some patients with severe disease that does not respond to maximal medical therapy. Recurrent CDI is a challenge to treat; no single effective therapy currently exists. Treatments include antibiotics, adjunct probiotics, fecal microbiota transplant and immune approaches. This Review discusses the various therapeutic approaches used for the treatment of refractory and recurrent CDI.

Antimicrobial susceptibilities and molecular epidemiology of clinical isolates of Clostridium difficile in taiwan

The antimicrobial susceptibility and virulence factors of Clostridium difficile clinical isolates in Taiwan have not previously been reported. One hundred and thirteen isolates were collected from two major teaching hospitals in Taiwan from 2001 to 2009. Molecular typing was performed by an automated repetitive extragenic palindromic sequence-based PCR (rep-PCR) method (DiversiLab; Bacterial Barcodes, Inc., Athens, GA) and PCR ribotyping. Detection of tcdA, tcdB, cdtA, and cdtB genes was performed using a multiplex PCR assay, and gyrA and gyrB genes of moxifloxacin-nonsusceptible isolates were sequenced. All isolates were susceptible to vancomycin and metronidazole. Ninety-five (84%) isolates were susceptible to moxifloxacin, and the MIC(90) for nemonoxacin was 4 μg/ml. Tigecycline showed favorable antibacterial activity (MIC(90) of 0.06 μg/ml). Thirteen rep-PCR types were identified as a predominant rep-PCR type (type A; non-North American pulsed-field gel electrophoresis type 1 [NAP1], -NAP7, or -NAP8) accounting for 52.2% (59 isolates). Nine of 18 moxifloxacin-nonsusceptible isolates belonged to the rep-PCR type A. The rep-PCR type A and C isolates were distinct from NAP1 (ribotype 027) and NAP8 (ribotype 078) as determined by PCR ribotyping. Seventy-four (65%) isolates harbored tcdA and tcdB, and 15 (13%) harbored cdtAB encoding binary toxin. Eleven isolates had a gene deletion in tcdC, including a 39-bp deletion (9 isolates) and an 18-bp deletion (2). In conclusion, dissemination of a predominant C. difficile clone in southern and northern Taiwan was noted. However, no NAP1 (ribotype 027) isolate could be discovered in this study.

Update on Clostridium difficile infection

PURPOSE OF REVIEW

This review summarizes the most recent epidemiological data and advances in research into the pathogenesis, diagnosis and treatment of Clostridium difficile infection (CDI).

RECENT FINDINGS

The epidemiology of CDI has changed with the emergence of hypervirulent strains. CDI rates have increased in the community, in children and in patients with inflammatory bowel disease. Although the North American pulsed-field gel electrophoresis type 1, restriction endonuclease analysis group BI, PCR ribotype 027 (NAP1/BI/027) strain remains prevalent in North America, surveillance suggests that it is decreasing in Europe. A similar strain, PCR ribotype 078, is emerging which is associated with community-associated CDI and has been isolated in animals and food products. The Society for Healthcare Epidemiology of America and the Infectious Diseases Society of America have published new guidelines on the epidemiology, diagnosis, treatment, infection control and environmental management of C. difficile. Several novel therapies for CDI are at different stages of development. There have been promising trial results with fidaxomicin, a novel antibiotic for the treatment of CDI and monoclonal antibodies against toxins A and B, which have been shown to significantly reduce CDI recurrence rates.

SUMMARY

Major advances have been made in our understanding of the spread and pathogenesis of C. difficile and new treatment options are becoming available.