Enhancement of NETosis by ACE2-cross-reactive anti-SARS-CoV-2 RBD antibodies in patients with COVID-19

BACKGROUND

High levels of neutrophil extracellular trap (NET) formation or NETosis and autoantibodies are related to poor prognosis and disease severity of COVID-19 patients. Human angiotensin-converting enzyme 2 (ACE2) cross-reactive anti-severe acute respiratory syndrome coronavirus 2 spike protein receptor-binding domain (SARS-CoV-2 RBD) antibodies (CR Abs) have been reported as one of the sources of anti-ACE2 autoantibodies. However, the pathological implications of CR Abs in NET formation remain unknown.

METHODS

In this study, we first assessed the presence of CR Abs in the sera of COVID-19 patients with different severity by serological analysis. Sera and purified IgG from CR Abs positive COVID-19 patients as well as a mouse monoclonal Ab (mAb 127) that can recognize both ACE2 and the RBD were tested for their influence on NETosis and the possible mechanisms involved were studied.

RESULTS

An association between CR Abs levels and the severity of COVID-19 in 120 patients was found. The CR Abs-positive sera and IgG from severe COVID-19 patients and mAb 127 significantly activated human leukocytes and triggered NETosis, in the presence of RBD. This NETosis, triggered by the coexistence of CR Abs and RBD, activated thrombus-related cells but was abolished when the interaction between CR Abs and ACE2 or Fc receptors was disrupted. We also revealed that CR Abs-induced NETosis was suppressed in the presence of recombinant ACE2 or the Src family kinase inhibitor, dasatinib. Furthermore, we found that COVID-19 vaccination not only reduced COVID-19 severity but also prevented the production of CR Abs after SARS-CoV-2 infection.

CONCLUSIONS

Our findings provide possible pathogenic effects of CR Abs in exacerbating COVID-19 by enhancing NETosis, highlighting ACE2 and dasatinib as potential treatments, and supporting the benefit of vaccination in reducing disease severity and CR Abs production in COVID-19 patients.

Phage transcriptional regulator X (PtrX)-mediated augmentation of toxin production and virulence in Clostridioides difficile strain R20291

Clostridioides difficile is a Gram-positive, anaerobic, and spore-forming bacterial member of the human gut microbiome. The primary virulence factors of C. difficile are toxin A and toxin B. These toxins damage the cell cytoskeleton and cause various diseases, from diarrhea to severe pseudomembranous colitis. Evidence suggests that bacteriophages can regulate the expression of the pathogenicity locus (PaLoc) genes of C. difficile. We previously demonstrated that the genome of the C. difficile RT027 strain NCKUH-21 contains a prophage-like DNA sequence, which was found to be markedly similar to that of the φCD38-2 phage. In the present study, we investigated the mechanisms underlying the φNCKUH-21-mediated regulation of the pathogenicity and the PaLoc genes expression in the lysogenized C. difficile strain R20291. The carriage of φNCKUH-21 in R20291 cells substantially enhanced toxin production, bacterial motility, biofilm formation, and spore germination in vitro. Subsequent mouse studies revealed that the lysogenized R20291 strain caused a more severe infection than the wild-type strain. We screened three φNCKUH-21 genes encoding DNA-binding proteins to check their effects on PaLoc genes expression. The overexpression of NCKUH-21_03890, annotated as a transcriptional regulator (phage transcriptional regulator X, PtrX), considerably enhanced toxin production, biofilm formation, and bacterial motility of R20291. Transcriptome analysis further confirmed that the overexpression of ptrX led to the upregulation of the expression of toxin genes, flagellar genes, and csrA. In the ptrX-overexpressing R20291 strain, PtrX influenced the expression of flagellar genes and the sigma factor gene sigD, possibly through an increased flagellar phase ON configuration ratio.

Predictive models for short-term mortality and length of hospital stay among adults with community-onset bacteraemia before and during the COVID-19 pandemic: application of early data dynamics

BACKGROUND

The development of scoring systems to predict the short-term mortality and the length of hospital stay (LOS) in patients with bacteraemia is essential to improve the quality of care and reduce the occupancy variance in the hospital bed.

METHODS

Adults hospitalised with community-onset bacteraemia in the coronavirus disease 2019 (COVID-19) and pre-COVID-19 eras were captured as the validation and derivation cohorts in the multicentre study, respectively. Model I incorporated all variables available on day 0, Model II incorporated all variables available on day 3, and Models III, IV, and V incorporated the variables that changed from day 0 to day 3. This study adopted the statistical and machine learning (ML) methods to jointly determine the prediction performance of these models in two study cohorts.

RESULTS

A total of 3,639 (81.4%) and 834 (18.6%) patients were included in the derivation and validation cohorts, respectively. Model IV achieved the best performance in predicting 30-day mortality in both cohorts. The most frequently identified variables incorporated into Model IV were deteriorated consciousness from day 0 to day 3 and deteriorated respiration from day 0 to day 3. Model V achieved the best performance in predicting LOS in both cohorts. The most frequently identified variables in Model V were deteriorated consciousness from day 0 to day 3, a body temperature ≤ 36.0 °C or ≥ 39.0 °C on day 3, and a diagnosis of complicated bacteraemia.

CONCLUSIONS

For hospitalised adults with community-onset bacteraemia, clinical variables that dynamically changed from day 0 to day 3 were crucial in predicting the short-term mortality and LOS.

COVID-19-associated candidiasis and the emerging concern of Candida auris infections

The incidence of COVID-19-associated candidiasis (CAC) is increasing, resulting in a grave outcome among hospitalized patients with COVID-19. The most alarming condition is the increasing incidence of multi-drug resistant Candida auris infections among patients with COVID-19 worldwide. The therapeutic strategy towards CAC caused by common Candida species, such as Candida albicans, Candida tropicalis, and Candida glabrata, is similar to the pre-pandemic era. For non-critically ill patients or those with a low risk of azole resistance, fluconazole remains the drug of choice for candidemia. For critically ill patients, those with a history of recent azole exposure or with a high risk of fluconazole resistance, echinocandins are recommended as the first-line therapy. Several novel therapeutic agents alone or in combination with traditional antifungal agents for candidiasis are potential options in the future. However, for multidrug-resistant C. auris infection, only echinocandins are effective. Infection prevention and control policies, including strict isolation of the patients carrying C. auris and regular screening of non-affected patients, are suggested to prevent the spread of C. auris among patients with COVID-19. Whole-genome sequencing may be used to understand the epidemiology of healthcare-associated candidiasis and to better control and prevent these infections.

Association of Single Nucleotide Polymorphisms in Nucleotide-Binding Domain Leucine-Rich Repeat Protein 1 with Clostridioides difficile Colonization or Infection

Introduction

Nucleotide-binding domain leucine-rich repeat protein (NLRP) is critical in the inflammasome-activation pathway, which is important for host survival and the clearance of Clostridioides difficile. Therefore, the influence of NLRP1 polymorphisms on C. difficile colonization (CdC) or infection (CDI) was analyzed.

Materials and Methods

A prospective cohort study consisted of hospitalized adults was conducted from January 2011 to January 2013. Single nucleotide polymorphisms (SNPs) of NLRP1, including rs12150220, rs2670660, rs6502867, rs878329, rs8182352, rs3744717, and rs11078571, were incorporating in analyses. The episodes of CdC and CDI were the primary and secondary outcome, respectively.

Results

Of the total of 509 eligible patients, 376 (73.9%) had neither CdC nor CDI, 104 (21.8%) had CdC without developing CDI, and 29 (4.3%) developed CDI during the study period. Through multivariate analyses, comorbid diabetes mellitus (adjusted odds ratio [AOR] 1.59, P=0.04) and CC genotype in NLRP1 rs3744717 (AOR 1.70, P=0.02) were recognized as the risk factor of CdC. After adjusting the independent predictors of CDI, in terms of comorbid diabetes mellitus (AOR 3.18, P=0.005) and prior exposure to ceftazidime/ceftriaxone (AOR 2.87, P=0.04) or proton pump inhibitors (AOR 3.86, P=0.001), patients with CC+GC genotype in NLRP1, rs878329 (AOR 2.39, P=0.03) remained a higher risk of CDI.

Conclusion

For hospitalized adults, the association of CC genotype in NLRP1 rs3744717 and CdC as well as the CC+GC genotype in NLRP1 rs878329 and CDI was respectively evidenced. We believed the prompt identification of patients having specific genotype in NLRP1 would prevent and improve the quality of care in CDI.

Peroxisome proliferator-activated receptor-γ as the gatekeeper of tight junction in Clostridioides difficile infection

Clostridioides difficile is a major causative pathogen of nosocomial antibiotic-associated diarrhea and severe colitis. Despite the use of vancomycin and fidaxomicin as standard drugs for the treatment of C. difficile infection (CDI), clinical relapse rates remain high. Therefore, new alternative therapeutics to treat CDI are urgently required. The nuclear receptor, peroxisome proliferator-activated receptor-γ (PPAR-γ), is mainly expressed in the adipose tissue and modulates lipid metabolism and insulin sensitization. Previous studies have shown that PPAR-γ is highly expressed in colonic tissues and regulates tight junction function in epithelial cells. However, the role of PPAR-γ in CDI pathogenesis remains unclear. In this study, we used a mouse model of CDI and found that both expression levels of PPAR-γ and the tight junction protein, occludin, were decreased in colonic tissues. Furthermore, to investigate the role of PPAR-γ in CDI, we used PPAR-γ defective mice and found that intestinal permeability and bacterial dissemination in these mice were significantly higher than those in wild-type mice during CDI. Administration of the PPAR-γ agonist, pioglitazone, to activate PPAR-γ activity improved the phenotypes of CDI, including bodyweight loss, inflammation, and intestinal integrity. Taken together, these results demonstrate that PPAR-γ is a potential therapeutic target in CDI, as it modulates colonic inflammation and integrity.

Risk Factors and Clinical Impact of Carbapenem-Resistant Enterobacterales Coinfections Among Hospitalized Patients with Clostridioides difficile Infection

Introduction

The risk factors and clinical impact of carbapenem-resistant Enterobacterales (CRE) coinfection among hospitalized patients with Clostridioides difficile infection (CDI) were analyzed in this study.

Materials and Methods

A clinical study was performed at the medical wards of Tainan Hospital, Ministry of Health and Welfare in southern Taiwan. Patients with CDI between January 2013 and April 2020 were included.

Results

Among 238 patients included for analysis, 22 (9.2%) patients developed CRE coinfections within 14 days before or after the onset of CDI. CDI patients with CRE coinfection had longer hospitalization stays (103.0 ± 97.0 days vs 42.5 ± 109.6 days, P = 0.01) than those without CRE coinfection. In the multivariate analysis, age (odds ratio [OR] 1.05, 95% confidence interval [CI] 1.01–1.10, P = 0.02) was independently associated with CRE coinfection. In contrast, underlying old stroke (OR 0.15, 95% CI 0.03–0.70, P = 0.02) was negatively linked to CRE coinfection.

Conclusion

Among patients with CDI, CRE coinfections were associated with prolonged hospitalization for CDI. Age was an independent risk factor for CRE coinfection among patients with CDI.

The emergence of Clostridioides difficile PCR ribotype 127 at a hospital in northeastern Taiwan

BACKGROUND

Several studies have highlighted the incidence of Clostridioides difficile infections (CDIs) in Taiwan and certain ribotypes have been related to severe clinical diseases. A study was conducted to investigate the polymerase chain reaction (PCR) ribotypes and genetic relatedness of clinical C. difficile strains collected from January 2009 to December 2015 at a hospital in northeastern Taiwan.

MATERIAL AND METHODS

A modified two-step typing algorithm for C. difficile was used by combining a modified 8-plex and 3'-truncated tcdA screening PCR. In addition, MLVA typing was adopted for investigation of bacterial clonality and transmission.

RESULTS

Among a total of 86 strains, 24 (28%) were nontoxigenic and 62 (72%) had both tcdA and tcdB (A + B+). No tcdA-negative and tcdB-positive (A^-B⁺) strains were identified. Binary toxin (CDT)-producing (cdtA+/cdtB+) strains were started to be identified in 2013. The 21 (34%) A⁺B⁺ clinical strains with binary toxin and tcdC deletion were identified as RT127 strains, which contained both RT078-lineage markers and fluoroquinolone (FQ)-resistant mutations (Thr82Ile in gyrA). Multiple loci variable-number tandem repeat analysis (MLVA) for phylogenetic relatedness of RT127 strains indicated that 20 of 21 strains belonged to a clonal complex that was identical to a clinical strain collected from southern Taiwan in 2011, suggestive of a clonal expansion in Taiwan.

CONCLUSION

A two-step typing method could rapidly confirm species identification and define the toxin gene profile of C. difficile isolates. The clonal expansion of RT127 strains in Taiwan indicates monitoring and surveillance of toxigenic C. difficile isolates from human, animal, and environment are critical to develop One Health prevention strategies.

Impacts of Corticosteroid Therapy at Acute Stage of Hospital-Onset Clostridioides difficile Infections

Introduction

The influence of corticosteroid therapy before or after the onset of Clostridioides difficile infections (CDIs) on the clinical outcomes of adults with hospital-onset CDIs was investigated.

Materials and Methods

A clinical study was conducted on the medical wards of a teaching hospital between January 2013 and April 2020. Adults (aged ≥ 20 years) with hospital-onset CDIs (ie, symptom onset at least 48 hours after hospitalization) were included. "Corticosteroid therapy during acute CDIs" was defined as the receipt of a corticosteroid at the prednisolone equivalent (PE) dose of ≥10 mg for at least 48 hours within one week after the CDI diagnosis. "Prior corticosteroid exposure" was defined as the receipt of a corticosteroid at the PE dose of ≥5 mg PE for at least 48 hours within one month before the CDI diagnosis.

Results

Of the 243 adults with hospital-onset CDIs, patients (44, 18.1%) who received corticosteroid therapy during acute CDIs were more likely to have prior corticosteroid exposure (86.4% vs 11.9%, P <0.001) and CDI episodes in intensive care units (31.8% vs 10.8%, P =0.001). Of note, a crucial association between corticosteroid therapy during acute CDIs and CDI recurrence was evidenced (13.6% vs 1.5%, P =0.002). Prior corticosteroid exposure was not associated with favorable CDI outcomes in terms of successful treatment (78.3% vs 74.9%, P =0.89), in-hospital crude mortality (17.4% vs 24.0%, P =0.61), or CDI recurrence (4.3% vs 5.3%, P = 1.00). However, for 177 patients without prior corticosteroid exposure, corticosteroid therapy during acute CDIs was linked to a higher proportion of CDI recurrence (33.3% vs 5.3%, P =0.046).

Conclusion

Corticosteroid therapy during acute CDIs might impact the recurrence of CDIs, particularly in those with a lack of prior corticosteroid exposure.

Reappraisal of the clinical role of metronidazole therapy for Clostridioides difficile infection in Taiwan: A multicenter prospective study

BACKGROUND/PURPOSE

Although metronidazole is not recommended to treat Clostridioides difficile infection (CDI) in Western countries, it was still to be recommended for the treatment of non-severe CDI among Taiwanese adults in 2020. This controversy in the clinical role of metronidazole therapy for CDI was examined in a prospective clinical study.

METHODS

The study was conducted from January 2015 to December 2016 in three hospitals in Taiwan. Metronidazole treatment failure (MTF) was defined as the persistence of diarrhea after six days of treatment, medication modification (shifting to oral vancomycin), or death after five days of therapy.

RESULTS

Overall, 325 patients receiving metronidazole for CDI were included. The overall MTF rate was 48.6% (158 patients). Leukocyte counts of >15,000 cells/mL in peripheral blood (odd ratio [OR] 1.81; P = 0.04) and congestive heart failure (OR 3.26; P = 0.02) were independently associated with MTF. The MTF rate for patients with leukocyte counts of ≤15,000 cells/mL and no congestive heart failure, leukocyte counts of >15,000 cells/mL and no congestive heart failure, leukocyte counts of ≤15,000 cells/mL and congestive heart failure, and leukocyte counts of >15,000 cells/mL and congestive heart failure were 44.2%, 51.8%, 73.3%, and 66.7%, respectively. Of note, patients who experienced MTF had a higher recurrence rate of CDI than those with metronidazole treatment success (13.9% vs. 6.0%, P = 0.02).

CONCLUSION

For Taiwanese adults with CDI, the failure rate of metronidazole therapy approached 50%, which suggests the reappraisal of the therapeutic role of metronidazole therapy, especially for patients with leukocytosis or underlying congestive heart failure.

Prognostic Effects of Delayed Administration of Appropriate Antimicrobials in Bacteraemic Adults Initially Presenting with Various Body Temperatures

Purpose

To investigate the different impact of delayed administration of appropriate antimicrobial therapy (AAT) on short-term mortality of bacteraemia patients initially presenting with various body temperatures (BTs).

Materials and Methods

A six-year, two-center cohort consisting of adults with community-onset bacteraemia in emergency departments (EDs) was retrospectively collected. Through the multivariable analyses, clinical impacts of delayed AAT, assessed by the time gap between the first dose of AAT and ED arrival, on 30-day mortality (primary outcomes) were respectively examined in the different groups of initial BTs (iBTs).

Results

Of the 3171 adults, despite the similarities of delayed AAT in six iBT categories, hourly AAT delay was associated with an average increase in 30-day mortality rates of 0.24% in the group of iBT <36.0℃, 0.40% in the 36.0℃–36.9℃ group, 0.48% in the 37.0℃–37.9℃ group, 0.59% in the 38.0℃–38.9℃ group, 0.58% in the 39.0℃–39.9℃ group, and 0.71% in the ≥40.0℃ group, after respective adjusting independent predictors of mortality. Furthermore, for 589 patients who inappropriately received empirical antimicrobial treatment (ie, delayed AAT ≥ 24 hours), with a cutoff of 34.0℃, each 1℃ increase in iBTs was independently associated with an average increase in 30-day mortality rates of 42%.

Conclusion

For adults with community-onset bacteraemia, the iBT-related differences in the prognostic impacts of delayed administration of appropriate antimicrobials might be evident.

Effects of Inappropriate Administration of Empirical Antibiotics on Mortality in Adults With Bacteraemia: Systematic Review and Meta-Analysis

Introduction

Bloodstream infections are associated with high mortality rates and contribute substantially to healthcare costs, but a consensus on the prognostic benefits of appropriate empirical antimicrobial therapy (EAT) for bacteraemia is lacking.

Methods

We performed a systematic search of the PubMed, Cochrane Library, and Embase databases through July 2021. Studies comparing the mortality rates of patients receiving appropriate and inappropriate EAT were considered eligible. The quality of the included studies was assessed using Joanna Briggs Institute checklists.

Results

We ultimately assessed 198 studies of 89,962 total patients. The pooled odds ratio (OR) for the prognostic impacts of inappropriate EAT was 2.06 (P < 0.001), and the funnel plot was symmetrically distributed. Among subgroups without between-study heterogeneity (I² = 0%), those of patients with severe sepsis and septic shock (OR, 2.14), Pitt bacteraemia scores of ≥4 (OR, 1.88), cirrhosis (OR, 2.56), older age (OR, 1.78), and community-onset/acquired Enterobacteriaceae bacteraemia infection (OR, 2.53) indicated a significant effect of inappropriate EAT on mortality. The pooled adjusted OR of 125 studies using multivariable analyses for the effects of inappropriate EAT on mortality was 2.02 (P < 0.001), and the subgroups with low heterogeneity (I² < 25%) exhibiting significant effects of inappropriate EAT were those of patients with vascular catheter infections (adjusted OR, 2.40), pneumonia (adjusted OR, 2.72), or Enterobacteriaceae bacteraemia (adjusted OR, 4.35). Notably, the pooled univariable and multivariable analyses were consistent in revealing the negligible impacts of inappropriate EAT on the subgroups of patients with urinary tract infections and Enterobacter bacteraemia.

Conclusion

Although the current evidence is insufficient to demonstrate the benefits of prompt EAT in specific bacteraemic populations, we indicated that inappropriate EAT is associated with unfavorable mortality outcomes overall and in numerous subgroups. Prospective studies designed to test these specific populations are needed to ensure reliable conclusions.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/, identifier: CRD42021270274.

Prognostic Effects of Inappropriate Empirical Antimicrobial Therapy in Adults With Community-Onset Bacteremia: Age Matters

Background

Studies have reported the effects of delayed administration of appropriate antimicrobial therapy (AAT) on the short-term prognosis of patients with bloodstream infections; however, whether there is an age-related difference in these effects remains debated.

Methods

In this 4-year multicenter case-control study, patients with community-onset bacteremia were retrospectively categorized into the "middle-aged" (45-64 years), "old" (65-74 years), and "very old" (≥75 years) groups. Two methods were adopted to investigate the prognostic effects of delayed AAT in each age group. First, its effects were, respectively, investigated, after adjustment for the independent predictors of 30-day mortality. Second, patients in each age group were matched by the closest propensity-score (PS), which was calculated by independent predictors of mortality; the survival curves and Pearson chi-square tests were adopted to disclose its effects in each PS-matching group.

Results

Each hour of delayed AAT resulted in an average increase in the 30-day crude mortality rate of 0.2% (P = 0.03), 0.4% (P < 0.001), and 0.7% (P < 0.001) in middle-aged (968 patients), old (683), and very old (1,265) patients, after, respectively, adjusting the independent predictors of mortality in each group. After appropriate PS-matching, no significant proportion differences in patient demographics, bacteremia characteristics, severity of bacteremia and comorbidities, and 15-day or 30-day crude mortality rates were observed between three matched groups (582 patients in each group). However, significant differences in survival curves between patients with delayed AAT > 24 or >48 h and those without delayed administration were demonstrated in each age group. Furthermore, the odds ratios of 30-day mortality for delayed AAT > 24 or >48 h were 1.73 (P = 0.04) or 1.82 (P = 0.04), 1.84 (P = 0.03) or 1.95 (P = 0.02), and 1.87 (P = 0.02) or 2.34 (P = 0.003) in the middle-aged, old, and very old groups, respectively. Notably, the greatest prognostic impact of delayed AAT > 24 or >48 h in the very old group and the smallest impact in the middle-aged group were exhibited.

Conclusion

For adults (aged ≥45 years) with community-onset bacteremia, the delayed AAT significantly impacts their short-term survival in varied age groups and the age-related differences in its prognostic impact might be evident.

Clostridium butyricum therapy for mild-moderate Clostridioides difficile infection and the impact of diabetes mellitus

The therapeutic effect of Clostridium butyricum for adults with Clostridioides difficile infection (CDI) was investigated. A retrospective study was conducted in medical wards of Tainan Hospital, Ministry of Health and Welfare, between January 2013 and April 2020. The disease severity of CDI was scored based on the Clinical Practice Guidelines of the IDSA/SHEA. Treatment success was defined as the resolution of diarrhea within six days of a therapeutic intervention without the need to modify the therapeutic regimen. In total, 241 patients developed CDI during hospitalization in the study period. The treatment success rates for the 99 patients with mild-moderate CDI among them were as follows: metronidazole, 69.4%; C. butyricum, 68.2%; metronidazole plus C. butyricum, 66.7%; and oral vancomycin, 66.7% (p=1.00). Patients with treatment success were less likely to have diabetes mellitus than those with treatment failure (38.2% vs. 61.3%, p=0.05). Patients treated with C. butyricum alone or in combination with metronidazole had shorter durations of diarrhea than those treated with metronidazole alone (3.1 ± 2.0 days or 3.5 ± 2.4 days vs. 4.2 ± 3.5 days; p=0.43 or 0.71), although the differences were not statistically significant. In conclusion, the treatment success rate of C. butyricum alone or in combination with metronidazole for patients with CDI was non inferior to that of metronidazole alone. The presence of diabetes mellitus in affected individuals is a risk factor for treatment failure.

Neutrophil Ratio of White Blood Cells as a Prognostic Predictor of Clostridioides difficile Infection

Introduction

A leukocyte count ≥15,000 cells/mL and serum creatinine of >1.5 mg/dL have been reported as two important predictors of severe CDI. However, the association of the differential ratios of blood leukocytes, and the prognosis of Clostridioides difficile infection (CDI) is not clear.

Materials and Methods

A clinical study was conducted at medical wards of Tainan Hospital, Ministry of Health and Welfare in southern Taiwan between January 2013 and April 2020. Hospitalized adults (aged ≥20 years) with hospital-onset CDI (ie, symptom onset after at least 48 hours of admission) were included.

Results

A total of 235 adults with an average age of 75.7 years and female predominance (51.5%), including 146 (62%) adults with non-severe CDI and 87 (38%) severe CDI, were included for analysis. Patients with severe CDI had a higher crude in-hospital mortality rate than patients with non-severe CDI (35.6% vs 18.5%, P = 0.005). Multivariate analysis revealed no association between a leukocyte count >15,000 cell/mL at the onset of CDI and in-hospital mortality (odds ratio [OR] 1.66, P = 0.21). In contrast, a neutrophil ratio >75% (OR 2.65, P = 0.02), serum creatinine >1.5 mg/L (OR 3.42, P = 0.03), and CDI caused by isolates harboring the tcdC gene (OR 3.54, P = 0.02) were independently associated with in-hospital mortality. Patients with a neutrophil ratio >85%, 80–85%, or 75–80% of serum leukocytes had a higher mortality rate (34.8%, 30.3%, or 34.4%, respectively) than patients with a neutrophil ratio of 70–75% or ≤75% (12.5% or 13.9%, respectively).

Conclusion

Serum creatinine >1.5 mg/L, a high neutrophil ratio of blood leukocytes (>75%), and the causative C. difficile harboring the tcdC gene was independent prognostic predictors in hospitalized adults with CDI.

The Potential of Probiotics to Eradicate Gut Carriage of Pathogenic or Antimicrobial-Resistant Enterobacterales

Probiotic supplements have been used to decrease the gut carriage of antimicrobial-resistant Enterobacterales through changes in the microbiota and metabolomes, nutrition competition, and the secretion of antimicrobial proteins. Many probiotics have shown Enterobacterales-inhibiting effects ex vivo and in vivo. In livestock, probiotics have been widely used to eradicate colon or environmental antimicrobial-resistant Enterobacterales colonization with promising efficacy for many years by oral supplementation, in ovo use, or as environmental disinfectants. In humans, probiotics have been used as oral supplements for infants to decease potential gut pathogenic Enterobacterales, and probiotic mixtures, especially, have exhibited positive results. In contrast to the beneficial effects in infants, for adults, probiotic supplements might decrease potentially pathogenic Enterobacterales, but they fail to completely eradicate them in the gut. However, there are several ways to improve the effects of probiotics, including the discovery of probiotics with gut-protection ability and antimicrobial effects, the modification of delivery methods, and the discovery of engineered probiotics. The search for multifunctional probiotics and synbiotics could render the eradication of “bad” Enterobacterales in the human gut via probiotic administration achievable in the future.

Clostridioides difficile infection: an emerging zoonosis?

INTRODUCTION

Clostridioides difficile (C. difficile) infection (CDI) is the most common cause of antibiotic-associated diarrhea and one of the common infections in healthcare facilities. In recent decades, there has been an emerging threat of community-acquired CDI (CA-CDI). Environmental transmission of C. difficile in the community setting has become a major concern, and animals are an important reservoir for C. difficile causing human diseases.

AREAS COVERED

In this article, the molecular epidemiology of C. difficile in animals and recent evidences of zoonotic transfer to humans are reviewed based on an electronic search in the databases of PubMed and Google Scholar.

EXPERT OPINION

C. difficile can be found in stool from diarrheal dogs and cats; therefore, household pets could be a potential source. C. difficile will threaten human health because hypervirulent C. difficile ribotype 078 strains have been found in retail chickens, pig farms, and slaughterhouses. Risk factors for fecal C. difficile carriage in animals include young age, dietary changes, and antibiotic abuse in domestic animals. With the advent of whole genome sequencing techniques, there will be more solid evidence indicating zoonotic transfer of C. difficile from animals to humans.

Gut Dysbiosis during COVID-19 and Potential Effect of Probiotics

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), an RNA virus of the family Coronaviridae, causes coronavirus disease 2019 (COVID-19), an influenza-like disease that chiefly infects the lungs through respiratory transmission. The spike protein of SARS-CoV-2, a transmembrane protein in its outer portion, targets angiotensin-converting enzyme 2 (ACE2) as the binding receptor for the cell entry. As ACE2 is highly expressed in the gut and pulmonary tissues, SARS-CoV-2 infections frequently result in gastrointestinal inflammation, with presentations ordinarily ranging from intestinal cramps to complications with intestinal perforations. However, the evidence detailing successful therapy for gastrointestinal involvement in COVID-19 patients is currently limited. A significant change in fecal microbiomes, namely dysbiosis, was characterized by the enrichment of opportunistic pathogens and the depletion of beneficial commensals and their crucial association to COVID-19 severity has been evidenced. Oral probiotics had been evidenced to improve gut health in achieving homeostasis by exhibiting their antiviral effects via the gut-lung axis. Although numerous commercial probiotics have been effective against coronavirus, their efficacies in treating COVID-19 patients remain debated. In ClinicalTrials.gov, 19 clinical trials regarding the dietary supplement of probiotics, in terms of Lactobacillus and mixtures of Bifidobacteria and Lactobacillus, for treating COVID-19 cases are ongoing. Accordingly, the preventive or therapeutic role of probiotics for COVID-19 patients can be elucidated in the near future.

The Role of Toll-Like Receptor-2 in Clostridioides difficile Infection: Evidence From a Mouse Model and Clinical Patients

Background

Clostridioides difficile is the leading cause of nosocomial infectious diarrhea. Toll-like receptors (TLRs) are the major components of innate immunity that sense pathogens. The relationship between TLRs and C. difficile infection (CDI) was analyzed in clinical patients and a mouse model.

Materials and Methods

A prospective investigation was conducted in medical wards of Tainan Hospital, Ministry of Health and Welfare, Tainan, Taiwan, from January 2011 to January 2013. Adult patients were followed up for the development of CDI. Single nucleotide polymorphisms (SNPs) of TLR2 and TLR4 were analyzed to assess the relationship between genetic polymorphisms and the development of CDI. A mouse model of CDI was used to investigate the pathogenic role of TLRs in CDI, TLR2 and TLR4 knockout (Tlr2-/- and Tlr4-/-) mice.

Results

In the prospective study, 556 patients were enrolled, and 6.5% (36) of patients, accounting for 3.59 episodes per 1000 patient-days, developed CDI. Of 539 patients with available blood samples, the TLR2 rs3804099 polymorphism was more often noted in those with CDI than in those without CDI (64.5% vs. 46.1%; P = 0.046) but was not significant in multivariate analysis. Because the TLR2 rs3804099 polymorphism was moderately associated with CDI, the role of TLR2 and TLR4 was further evaluated in a mouse model. Both Tlr2-/- and Tlr4-/- mice showed more severe CDI disease than wild-type mice in terms of body weight change and fecal content five days after oral challenge with C. difficile. Furthermore, Tlr2-/- mice suffered from more severe disease than Tlr4-/- mice, as evidenced by stool consistency, cecum weight, and survival rate.

Conclusion

The TLR2 rs3804099 polymorphism is marginally associated with the development of CDI, and the pathogenic role of TLR2 is further supported by a mouse model.

Inhibition of spores to prevent the recurrence of Clostridioides difficile infection - A possibility or an improbability?

Clostridioides difficile is one of the most common nosocomial gastrointestinal pathogens, and recurrence is a problematic issue because approximately 20-30% of patients experience at least one episode of recurrence, even after treatment with a therapeutic drug of choice for C. difficile infection (CDI), such as vancomycin. CDI recurrence has a multifactorial complex mechanism, in which gut microbiota disruption coincident with viable C. difficile spores, is considered the most important factor. The effectiveness of an anti-C. difficile antimicrobial agent against CDI cannot guarantee its inhibitory effect on C. difficile spores and vice versa. However, an antimicrobial agent, such as fidaxomicin, which has a good inhibitory effect on both C. difficile vegetative cells and spores is assumed to not only treat CDI but also prevent its recurrence. Prolonged adherence to the exosporium has been proposed as a possible mechanism of inhibiting spores, and as a result, redesigning anti-C. difficile antimicrobial agents with the ability to adhere to the exosporium may provide another pathway for the development of anti-C. difficile spore agents. For example, vancomycin lacks an inhibitory effect against C. difficile spores, but a vancomycin-loaded spore-targeting iron oxide nanoparticle that selectively binds to C. difficile spores has been developed to successfully delay spore germination. Some new antimicrobial agents in phase II clinical trials, including cadazolid and ridinilazole, have shown exceptional anti-C. difficile and spore-inhibiting effects that can be expected to not only treat CDI but also prevent its recurrence in the future.

Risk factors and clinical impact of bacteremia due to carbapenem-nonsusceptible Enterobacteriaceae: A multicenter study in southern Taiwan

BACKGROUND

The emergence of carbapenem-non-susceptible Enterobacteriaceae (CnSE) infections is a public health threat. This study investigated the risk factors and clinical impact of bacteremia due to CnSE.

MATERIAL AND METHODS

The study was conducted at three hospitals in southern Taiwan between January 1, 2017, and October 31, 2019. Only the first episode of CnSE bacteremia from each adult was included. For one episode of CnSE bacteremia, two subsequent bacteremic episodes due to carbapenem-susceptible Enterobacteriaceae isolates in each hospital were included as the controls.

RESULTS

Among a total of 641 episodes of monomicrobial Enterobacteriaceae bacteremia were noted, 47 (7.3%) of which were of CnSE bacteremia. Ninety-four episodes of carbapenem-susceptible Enterobacteriaceae (CSE) bacteremia were selected as the controls for further analyses. In the multivariate analysis, hypertension (odds ratio [OR], 4.21; P = 0.005), Pitt bacteremia score (OR, 1.61; P = 0.002), and nosocomial bacteremia (OR, 3.30; P = 0.01) were associated with carbapenem nonsusceptibility among Enterobacteriaceae bacteremia. The most abundant CnSE isolate was Klebsiella pneumoniae (91.5%), followed by Klebsiella oxytoca (6.4%) and Escherichia coli (2.1%). Patients with CnSE bacteremia had a higher overall in-hospital mortality rate than those with CSE bacteremia (53.2% vs. 23.4%, P = 0.001). Moreover, in the multivariate analysis, the in-hospital mortality was significantly associated with higher Pitt bacteremia score (OR, 1.38; P = 0.02) and marginally associated with CnSE infections (OR, 2.44; P = 0.06).

CONCLUSION

Among adults with Enterobacteriaceae bacteremia, carbapenem nonsusceptibility, male sex, and the presence of hypertension or chronic kidney disease indicate a poor prognosis during hospitalization.

Risk of non-typhoidal Salmonella vascular infections is increased with degree of atherosclerosis and inflammation: A multicenter study in southern Taiwan

BACKGROUND

Atherosclerosis and vascular inflammatory response have been considered as risk factors for non-typhoidal Salmonella (NTS) vascular infection. The study aims to assess the risk of vascular infection by measuring atherosclerosis severity, NTS vascular infection (NTSVI) score, and serum levels of inflammatory markers in people with NTS bacteremia.

METHODS

A prospective observational study was conducted in two medical centers and two regional hospitals. Adults aged ≥50 years with NTS bacteremia who underwent computed tomography (CT) scan for revealing vascular infections were enrolled. The degree of atherosclerosis was scaled by a calcium score determined by a CT scan. Serum concentrations of inflammatory biomarkers were determined in the patients enrolled in a medical center.

RESULTS

Fourteen (20.3%) of 69 patients with NTS bacteremia had vascular infections. Calcium scores over the thoracic (12,540 vs. 3,261, P = 0.0005) and abdominal (9755 vs. 3,461, P = 0.0006) aorta of those with vascular infections were higher than those without vascular infection. All vascular infections were present in the high-risk group (NTSVI score ≥1), yielding a sensitivity of 100% and specificity of 30.9%. Among 17 low-risk patients (NTSVI score <1), none had vascular infections, resulting in a negative predictive value of 100%. Higher plasma concentrations of IL-1β were detected in the cases of vascular infection than those in the control group (23.6 vs. 1.06 pg/mL, P = 0.001).

CONCLUSION

Atherosclerosis of the aorta which is associated with a positive NTSVI score can predict the occurrence of vascular infections and serum IL-1β could be a biomarker for vascular infection in patients with NTS bacteremia.

Clostridioides difficile spores stimulate inflammatory cytokine responses and induce cytotoxicity in macrophages

Clostridioides difficile is a gram-positive, spore-forming anaerobic bacterium, and the leading cause of antibiotic-associated diarrhea worldwide. During C. difficile infection, spores germinate in the presence of bile acids into vegetative cells that subsequently colonize the large intestine and produce toxins. In this study, we demonstrated that C. difficile spores can universally adhere to, and be phagocytosed by, murine macrophages. Only spores from toxigenic strains were able to significantly stimulate the production of inflammatory cytokines by macrophages and subsequently induce significant cytotoxicity. Spores from the isogenic TcdA and TcdB double mutant induced significantly lower inflammatory cytokines and cytotoxicity in macrophages, and these activities were restored by pre-exposure of the spores to either toxins. These findings suggest that during sporulation, spores might be coated with C. difficile toxins from the environment, which could affect C. difficile pathogenesis in vivo.

Application of Microbiome Management in Therapy for Clostridioides difficile Infections: From Fecal Microbiota Transplantation to Probiotics to Microbiota-Preserving Antimicrobial Agents

Oral vancomycin and metronidazole, though they are the therapeutic choice for Clostridioides difficile infections (CDIs), also markedly disturb microbiota, leading to a prolonged loss of colonization resistance to C. difficile after therapy; as a result, their use is associated with a high treatment failure rate and high recurrent rate. An alternative for CDIs therapy contains the delivery of beneficial (probiotic) microorganisms into the intestinal tract to restore the microbial balance. Recently, mixture regimens containing Lactobacillus species, Saccharomyces boulardii, or Clostridium butyricum have been extensively studied for the prophylaxis of CDIs. Fecal microbiota transplantation (FMT), the transfer of (processed) fecal material from healthy donors to patients for treating CDIs, combined with vancomycin was recommended as the primary therapy for multiple recurrent CDIs (rCDIs). Either probiotics or FMT have been utilized extensively in preventing or treating CDIs, aiming at less disturbance in the microbiota to prevent rCDIs after therapy cessation. Otherwise, many newly developed therapeutic agents have been developed and aim to preserve microbiota during CDI treatment to prevent disease recurrence and might be useful in clinical patients with rCDIs in the future.

Clinical Impact and Risk Factors of Nonsusceptibility to Third-Generation Cephalosporins Among Hospitalized Adults with Monomicrobial Enterobacteriaceae Bacteremia in Southern Taiwan: A Multicenter Study

Background

Reducing the effectiveness of broad-spectrum cephalosporins against Enterobacteriaceae infections has been recognized. This study aimed to investigate risk factors and clinical significance of third-generation cephalosporin nonsusceptibility (3GC-NS) among the cases of monomicrobial Enterobacteriaceae bacteremia (mEB) at regional or district hospitals.

Methods

The study was conducted at three hospitals in southern Taiwan between Jan. 2017 and Oct. 2019. Only the first episode of mEB from each adult (aged ≥20 years) was included. The primary outcome was in-hospital crude mortality.

Results

Overall there were 499 episodes of adults with mEB included, and their mean age was 74.5 years. Female predominated, accounting for 53% of all patients. Escherichia coli (62%) and Klebsiella pneumoniae (21%) were two major causative species. The overall mortality rate was 15% (73/499), and patients infected by 3GC-NS isolates (34%, 172/499) had a higher mortality rate than those by 3GC-susceptible isolates (66%, 327/499) (21% vs 11%, P=0.005). By the multivariate analysis, 3GC-NS was the only independent prognostic determinant (adjusted odds ratio [AOR], 1.78; P=0.04). Of note, male (AOR 2.02, P=0.001), nosocomial-acquired bacteremia (AOR 2.77, P<0.001), and usage of nasogastric tube (AOR 2.01, P=0.002) were positively associated with 3GC-NS, but P. mirabilis bacteremia (AOR 0.28, P=0.01) and age (AOR 0.98, P=0.04) negatively with 3GC-NS.

Conclusion

For adults with Enterobacteriaceae bacteremia, 3GC-NS signifies a significant prognostic impact. Efforts to rapid identification of such antimicrobial resistance profiles should be incorporated into antimicrobial stewardship programs to achieve favorable outcomes.

Clostridioides difficile infection in patients with hematological malignancy: A multicenter study in Taiwan

BACKGROUND

Among the individuals with hematological malignancy (HM) complicated with Clostridioides difficile infection (CDI), the variables associated with in-hospital mortality and recurrence of CDI were investigated.

MATERIAL AND METHODS

Including adults with HM and those without malignancy suffering from CDI from January 2015 to December 2016 in three hospitals in Taiwan.

RESULTS

Totally 314 patients including 77 with HM and 237 patients without malignancy were included. HM patients more often had low leukocyte counts (<500 cells/mL: 28.6% vs. 2.1%) than those without malignancy and more patients without malignancy had severe CDI than patients with HM (31.6% vs. 14.3%, P = .003), according to the severity score of IDSA/SHEA. Patients with HM had a higher recurrence rate of CDI (14.3%, 11/77 vs. 7.2%, 17/237; P = .07) and longer hospital stay (47.2 ± 40.8 days vs. 33.3 ± 37.3 days; P = .006) than those without malignancy. In the multivariate analyses for those with HM and CDI, the in-hospital mortality was associated with vancomycin-resistant Enterococcus (VRE) colonization or infection (odds ratio [OR] 7.72; P = .01), and C. difficile ribotype 078 complex infection (OR 9.22; P = .03). Moreover underlying hematological malignancy (OR 2.74; P = .04) and VRE colonization/infection (OR 2.71; P = .02) were independently associated with CDI recurrence.

CONCLUSION

Patients with HM complicated with CDI were often regarded as non-severe infection, but had a similar in-hospital mortality rate as those without malignancy. CDI due to ribotype 078 complex isolates heralded a poor prognosis among HM patients.

A multicenter, randomized, open-label, controlled trial to evaluate the efficacy and tolerability of hydroxychloroquine and a retrospective study in adult patients with mild to moderate coronavirus disease 2019 (COVID-19)

Objective

In this study, we evaluated the efficacy of hydroxychloroquine (HCQ) against coronavirus disease 2019 (COVID-19) via a randomized controlled trial (RCT) and a retrospective study.

Methods

Subjects admitted to 11 designated public hospitals in Taiwan between April 1 and May 31, 2020, with COVID-19 diagnosis confirmed by pharyngeal real-time RT-PCR for SARS-CoV-2, were randomized at a 2:1 ratio and stratified by mild or moderate illness. HCQ (400 mg twice for 1 d or HCQ 200 mg twice daily for 6 days) was administered. Both the study and control group received standard of care (SOC). Pharyngeal swabs and sputum were collected every other day. The proportion and time to negative viral PCR were assessed on day 14. In the retrospective study, medical records were reviewed for patients admitted before March 31, 2020.

Results

There were 33 and 37 cases in the RCT and retrospective study, respectively. In the RCT, the median times to negative rRT-PCR from randomization to hospital day 14 were 5 days (95% CI; 1, 9 days) and 10 days (95% CI; 2, 12 days) for the HCQ and SOC groups, respectively (p = 0.40). On day 14, 81.0% (17/21) and 75.0% (9/12) of the subjects in the HCQ and SOC groups, respectively, had undetected virus (p = 0.36). In the retrospective study, 12 (42.9%) in the HCQ group and 5 (55.6%) in the control group had negative rRT-PCR results on hospital day 14 (p = 0.70).

Conclusions

Neither study demonstrated that HCQ shortened viral shedding in mild to moderate COVID-19 subjects.

Multicenter evaluation of two chemiluminescence and three lateral flow immunoassays for the diagnosis of COVID-19 and assessment of antibody dynamic responses to SARS-CoV-2 in Taiwan

This multicenter, retrospective study included 346 serum samples from 74 patients with coronavirus disease 2019 (COVID-19) and 194 serum samples from non-COVID-19 patients to evaluate the performance of five anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibody tests, i.e. two chemiluminescence immunoassays (CLIAs): Roche Elecsys® Anti-SARS-CoV-2 Test (Roche Test) and Abbott SARS-CoV-2 IgG (Abbott Test), and three lateral flow immunoassays (LFIAs): Wondfo SARS-CoV-2 Antibody Test (Wondfo Test), ASK COVID-19 IgG/IgM Rapid Test (ASK Test), and Dynamiker 2019-nCoV IgG/IgM Rapid Test (Dynamiker Test). We found high diagnostic sensitivities (%, 95% confidence interval [CI]) for the Roche Test (97.4%, 93.4–99.0%), Abbott Test (94.0%, 89.1–96.8%), Wondfo Test (91.4%, 85.8–94.9%), ASK Test (97.4%, 93.4–99.0%), and Dynamiker Test (90.1%, 84.3–94.0%) after >21 days of symptom onset. Meanwhile, the diagnostic specificity was 99.0% (95% CI, 96.3–99.7%) for the Roche Test, 97.9% (95% CI, 94.8–99.2%) for the Abbott Test, and 100.0% (95% CI, 98.1–100.0%) for the three LFIAs. Cross-reactivity was observed in sera containing anti-cytomegalovirus (CMV) IgG/IgM antibodies and autoantibodies. No difference was observed in the time to seroconversion detection of the five serological tests. Specimens from patients with COVID-19 pneumonia demonstrated a shorter seroconversion time and higher chemiluminescent signal than those without pneumonia. Our data suggested that understanding the dynamic antibody response after COVID-19 infection and performance characteristics of different serological test are crucial for the appropriate interpretation of serological test result for the diagnosis and risk assessment of patient with COVID-19 infection.

Fecal microbiota transplantation for Clostridium difficile infection in Taiwan: Establishment and implementation

Clostridium difficile infection (CDI) remains a major public health issue, and fecal microbiota transplantation (FMT) has become one of the standard therapies for recurrent or refractory CDI. When compared to medical therapies, such as metronidazole or vancomycin, FMT has a high rate of treatment response with acceptable safety and efficiency. Following promulgation of the amendments in September 2018 in Taiwan, FMT has been indicated for recurrent or refractory CDI. The Taiwan Microbiota Consortium contributed to the Taiwan FMT Expert Consensus, which established basic norms and stipulated essential principles, including the indications for transplantation, eligible locations and personnel, donor screening policies, fecal sample handling, and post-FMT follow-up. However, establishing an eligible FMT team in a qualified hospital remains a clinical challenge, and the requirement for facilities and well-screened donors impedes the implementation of FMT. In this review, we aim to provide domestic FMT teams with explicit instructions to facilitate realization and increase the practice of FMT. Based on the Taiwan FMT Expert Consensus and current regulations, we performed a literature review and integrated the experiences of Taiwanese multidisciplinary experts into this article. The content intends to offer clinicians up-to-date evidence and highlight the essential points of FMT.

Corrigendum: The ATP-P2X7 Signaling Axis Is an Essential Sentinel for Intracellular Clostridium difficile Pathogen-Induced Inflammasome Activation

[This corrects the article DOI: 10.3389/fcimb.2018.00084.].

Nationwide surveillance of ribotypes and antimicrobial susceptibilities of toxigenic Clostridium difficile isolates with an emphasis on reduced doxycycline and tigecycline susceptibilities among ribotype 078 lineage isolates in Taiwan

Objectives

The information of antimicrobial susceptibility, toxin gene, and ribotype distribution of toxigenic Clostridium difficile isolates in Taiwan remain limited.

Patients and methods

The study was conducted from January 2015 to December 2016 in 5 hospitals in Taiwan. Adults aged ≥20 years with a hospital stay for >5 days were included, and those with colectomy or intestinal infection due to other enteropathogens were excluded. Multiplex PCR was used to detect tcdA, tcdB, cdtA, cdtB, and tcdC deletions, and antimicrobial susceptibility for metronidazole, vancomycin, doxycycline, and tigecycline was investigated. Ribotypes of those isolates with tcdC deletion and tcdA+/tcdB+ were determined.

Results

Of 1112 C. difficile isolates collected from adults at 5 hospitals, 842 were toxigenic, including 749 (89.0%) tcdA+/tcdB+ isolates and 93 (11.0%) tcdA−/tcdB+. Of the toxigenic isolates, 76 (9.0%) had a tcdC deletion and were cdtA+/cdtB+, indicative of hypervirulence, and RT078 lineage, including RT126, RT127, and RT078, predominated (n=53, 76.3%). Similar to the susceptibility data in Asia countries, metronidazole or vancomycin resistance was rare, noted in 1.2% or 2.1%, respectively. Reduced doxycycline susceptibility (minimum inhibitory concentration [MIC] of ≥8 mg/L) was more common among RT078 lineage than non-RT078 lineage (75.9%, 44/58 vs 6.0%, 47/784; P<0.001). Also reduced tigecycline susceptibility (MIC ≥0.125 mg/L) was more common among RT078 lineage (20.7%, 12/58 vs 6.5%, 51/784; P<0.001).

Conclusion

In Taiwan, toxigenic C. difficile isolates remain susceptible to metronidazole and vancomycin. RT078 lineage predominated among toxigenic isolates with cdtA, cdtB, and tcdC deletion, and more often had reduced doxycycline and tigecycline susceptibility than the isolates other than RT078 lineage.

The ATP-P2X7 Signaling Axis Is an Essential Sentinel for Intracellular Clostridium difficile Pathogen-Induced Inflammasome Activation

Clostridium difficile infection (CDI) is the leading cause of nosocomial infection in hospitalized patients receiving long-term antibiotic treatment. An excessive host inflammatory response is believed to be the major mechanism underlying the pathogenesis of C. difficile infection, and various proinflammatory cytokines such as IL-1β are detected in patients with C. difficile infection. IL-1β is known to be processed by caspase-1, a cysteine protease that is regulated by a protein complex called the inflammasome, which leads to a specialized form of cell death called pyroptosis. The function of inflammasome activation-induced pyroptosis is to clear or limit the spread of invading pathogens via infiltrated neutrophils. Here, we focused on inflammasome activation induced by intact C. difficile to re-evaluate the nature of inflammasome activation in CDI pathogenesis, which could provide information that leads to an alternative therapeutic strategy for the treatment of this condition in humans. First, we found that caspase-1-dependent IL-1β production was induced by C. difficile pathogens in macrophages and increased in a time-dependent manner. Moreover, intracellular toxigenic C. difficile was essential for ATP-P2X₇ pathway of inflammasome activation and subsequent caspase-1-dependent pyroptotic cell death, leading to the loss of membrane integrity and release of intracellular contents such as LDH. Notably, we also observed that bacterial components such as surface layer proteins (SLPs) were released from pyroptotic cells. In addition, pro-IL-1β production was completely MyD88 and partially TLR2 dependent. Finally, to investigate the role of the caspase-1-dependent inflammasome in host defense, we found that colonic inflammasome activation was also induced by CDI and that caspase-1 inhibition by Ac-YVAD-CMK led to increased disease progression and C. difficile load. Taken together, the present results suggest that MyD88 and TLR2 are critical component in pro-IL-1β production and intracellular C. difficile following the ATP-P2X₇ pathway of inflammasome activation and pyroptosis, which play important roles in host defense through the utilization of inflammation-mediated bacterial clearance mechanisms during C. difficile infection.

Lauric Acid Is an Inhibitor of Clostridium difficile Growth in Vitro and Reduces Inflammation in a Mouse Infection Model

Clostridium difficile is a Gram-positive, spore-forming anaerobic human gastrointestinal pathogen. C. difficile infection (CDI) is a major health concern worldwide, with symptoms ranging from diarrhea to pseudomembranous colitis, toxic megacolon, sepsis, and death. CDI onset and progression are mostly caused by intestinal dysbiosis and exposure to C. difficile spores. Current treatment strategies include antibiotics; however, antibiotic use is often associated with high recurrence rates and an increased risk of antibiotic resistance. Medium-chain fatty acids (MCFAs) have been revealed to inhibit the growth of multiple human bacterial pathogens. Components of coconut oil, which include lauric acid, have been revealed to inhibit C. difficile growth in vitro. In this study, we demonstrated that lauric acid exhibits potent antimicrobial activities against multiple toxigenic C. difficile isolates in vitro. The inhibitory effect of lauric acid is partly due to reactive oxygen species (ROS) generation and cell membrane damage. The administration of lauric acid considerably reduced biofilm formation and preformed biofilms in a dose-dependent manner. Importantly, in a mouse infection model, lauric acid pretreatment reduced CDI symptoms and proinflammatory cytokine production. Our combined results suggest that the naturally occurring MCFA lauric acid is a novel C. difficile inhibitor and is useful in the development of an alternative or adjunctive treatment for CDI.

Comparative genomic analysis of Clostridium difficile ribotype 027 strains including the newly sequenced strain NCKUH-21 isolated from a patient in Taiwan

Background

Clostridium difficile is a Gram-positive anaerobe and the leading cause of antibiotic-associated diarrhea worldwide. The emergence of ribotype 027 (RT027) strains is associated with increased incidence of infection and mortality. To further understand the relationship between C. difficile NCKUH-21, a RT027 strain isolated from a patient in Taiwan, and other RT027 strains, we performed whole-genome shotgun sequencing on NCKUH-21 and comparative genomic analyses.

Results

The genome size, G+C content, and gene number for the NCKUH-21 strain were determined to be similar to those for other C. difficile strains. The core genome phylogeny indicated that the five RT027 strains R20291, CD196, NCKUH-21, BI1, and 2007855 formed a clade. A pathogenicity locus, tcdR-tcdB-tcdE-orf-tcdA-tcdC, was conserved in the genome. A genomic region highly similar to the Clostridium phage \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\upvarphi$$\end{document}φCD38-2 was present in the NCKUH-21 strain but absent in the other RT027 strains and designated as the prophage \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\upvarphi$$\end{document}φNCKUH-21. The prophage \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\upvarphi$$\end{document}φNCKUH-21 genes were significantly higher in G+C content than the other genes in the NCKUH-21 genome, indicating that the prophage does not match the base composition of the host genome.

Conclusions

This is the first whole-genome analysis of a RT027 C. difficile strain isolated from Taiwan. Due to the high identity with \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\upvarphi$$\end{document}φCD38-2, the prophage identified in the NCKUH-21 genome has the potential to regulate toxin production. These results provide important information for understanding the pathogenicity of RT027 C. difficile in Taiwan.

Electronic supplementary material

The online version of this article (10.1186/s13099-017-0219-4) contains supplementary material, which is available to authorized users.

Clinical benefits of antimicrobial de-escalation in adults with community-onset monomicrobial Escherichia coli, Klebsiella species and Proteus mirabilis bacteremia

The clinical benefits of an antimicrobial de-escalation strategy were compared with those of a no-switch strategy in bacteremic patients. Adults with community-onset monomicrobial Escherichia coli, Klebsiella species and Proteus mirabilis bacteremia treated empirically using broad-spectrum beta-lactams, including third-generation cephalosporins (GCs), fourth-GC or carbapenems, were treated definitively with first- or second-GCs (de-escalation group), the same regimens as empirical antibiotics (no-switch group), or antibiotics with a broader-spectrum than empirical antibiotics (escalation group). The eligible 454 adults were categorized as the de-escalation (231 patients, 50.9%), no-switch (177, 39.0%), and escalation (46, 10.1%) groups. Patients with de-escalation therapy were more often female, had less critical illness and fatal comorbidity, and had a higher survival rate than patients in the other two groups. After propensity score matching in the de-escalation and no-switch groups, critical illness at onset (Pitt bacteremia score ≥ 4; 16.5% vs. 12.7%; P = 0.34) or day 3 (2.5% vs. 2.5%; P = 1.00), fatal comorbidity (16.5% vs. 21.5%; P = 0.25), time to defervescence (4.6 vs. 4.7 days; P = 0.89), hospital stays (11.5 vs. 10.3 days; P = 0.13) and 4-week crude mortality rate (4.4% vs. 4.4%; P = 1.00) were similar. However, lower antibiotic cost (mean: 212.1 vs. 395.6 US$, P <0.001) and fewer complications of bloodstream infections due to resistant pathogens (0% vs. 5.1%, P = 0.004) were observed in the de-escalation group. De-escalation to narrower-spectrum cephalosporins is safe and cost-effective for adults with community-onset EKP bacteremia stabilized by empirical broad-spectrum beta-lactams.

Role of cytokine changes in clozapine-induced fever: A cohort prospective study

AIM

Clozapine-associated fever is common but the specific cytokine changes and treatment durations that may cause fever remain unknown. We investigated the association between inflammatory cytokine changes and clozapine-induced fever in patients who were treated with clozapine.

METHODS

Forty-three patients with schizophrenia or schizoaffective disorder, diagnosed by using the Chinese Version of the Mini International Neuropsychiatric Interview, were treated with clozapine for the first time (first-time use group, n = 22) or for more than 6 months (long-term use group, n = 21). The Positive and Negative Syndrome Scale, tympanic temperature, and levels of tumor necrosis factor-α (TNF-α), interferon-γ (INF-γ), interleukin-2 (IL-2), and interleukin-6 (IL-6) were determined at baseline and weeks 1, 2, 3, 4, and 6. A multiple linear regression with generalized estimating equation methods was used to analyze the association between the changes in the cytokine levels and clozapine-induced fever in the different groups.

RESULTS

The IL-6 level changes were significantly different between the two groups (P = 0.04). In the first-time use group, the fever rate was increased (47.1%) compared with the long-term use group (5.6%, P = 0.005). Moreover, in these patients, the TNF-α, INF-γ, IL-2, and IL-6 levels were significantly (P < 0.001) different from patients who did not develop a fever. An interaction effect with the different treatment duration groups and fever development was only significant for IL-6 (P < 0.001).

CONCLUSION

Patients who were treated with clozapine for the first time have an increased rate of developing a fever, and IL-6 might have a specific role in the interaction effect between treatment duration and fever development.

Comparing the therapeutic efficacies of third-generation cephalosporins and broader-spectrum β-lactams as appropriate empirical therapy in adults with community-onset monomicrobial Enterobacteriaceae bacteraemia: a propensity score matched analysis

In this study, the therapeutic efficacy of third-generation cephalosporins (3GCs) was compared with that of broader-spectrum β-lactams (BSBLs) [fourth-generation cephalosporins (4GCs) and carbapenems] as empirical therapy in adults with community-onset monomicrobial Enterobacteriaceae bacteraemia. Compared with those in the 3GC group (n = 477), a significantly higher proportion of patients in the BSBL group (n = 141) had initial presentation with severe sepsis or septic shock, critical illness (Pitt bacteraemia score ≥4) at bacteraemia onset and fatal co-morbidities (McCabe classification). For propensity score matching, 318 of the 477 patients in the 3GC group were matched with 106 patients in the BSBL group with the closest propensity scores on the basis of five independent predictors of 28-day mortality. After appropriate matching, no significant differences were observed in major baseline characteristics between the 3GC and BSBL groups in terms of causative micro-organism, bacteraemia severity, major source of bacteraemia, major co-morbidities and severity of co-morbidity. Consequently, the early clinical failure rate (12.9% vs. 12.3%; P = 0.87), bacteraemia severity (Pitt bacteraemia score ≥4; 4.6% vs. 8.2%; P = 0.17) at Day 3, and 3-day (3.8% vs. 7.5%; P = 0.11) and 28-day (13.2% vs. 17.0%; P = 0.33) crude mortality rates between the two groups were similar. These data suggest that the efficacy of 3GCs is similar to that of 4GCs or carbapenems when used as empirical antimicrobial therapy for community-onset Enterobacteriaceae bacteraemia.

Community-onset Clostridium difficile infection at a tertiary medical center in southern Taiwan, 2007-2015

BACKGROUND

Clostridium difficile infection (CDI) is well-known as the major cause of infectious diarrhea in hospitalized patients. Community-onset CDI (CO-CDI) is an emerging threat. However, clinical information of CO-CDI in Taiwan remains scarce.

METHODS

A retrospective study was conducted at a medical center in southern Taiwan. Symptomatic patients between 2007 and 2015 with C. difficile toxin or tcdB detected in stool were identified as CDI, and were classified as CO-CDI [including community-associated CDI (CA-CDI) and community-onset health care facility-associated CDI (CO-HCFA-CDI)] and health care facility-onset CDI (HCFO-CDI).

RESULTS

Of 427 patients, 15 (3.5%) were CA-CDI, 49 (11.5%) CO-HCFA-CDI, and 363 (85.0%) HCFO-CDI. Despite major involvement of the elderly (mean age: 66.1 years vs. 69.9 years, p = 0.46), no significant differences were noted between CA-CDI and CO-HCFA-CDI groups, except that solid organ cancer was more common in the CO-HCFA-CDI group. The CO-CDI group more often presented with abdominal pain but had shorter hospital stays and less exposure of proton-pump inhibitors or broad-spectrum antibiotics than the HCFO-CDI group did. The mortality rate related to CDI was 4.7% (3 patients) in the CO-CDI group. Despite a lower in-hospital mortality rate in the CO-CDI group (10.9% vs. 22.0%; p = 0.04), the recurrence rate was similar (10.9% vs. 7.2%; p = 0.3).

CONCLUSIONS

CO-CDI is not common but associated with substantial morbidity and mortality. Physicians should put CDI into consideration among patients who present community-onset fever, diarrhea, or abdominal pain alone or in combination.

Predominance of Clostridium difficile Ribotypes 017 and 078 among Toxigenic Clinical Isolates in Southern Taiwan

Ribotypes and toxin genotypes of clinical C. difficile isolates in Taiwan are rarely reported. A prospective surveillance study from January 2011 to January 2013 was conducted at the medical wards of a district hospital in southern Taiwan. Of the first toxigenic isolates from 120 patients, 68 (56.7%) of 120 isolates possessed both tcdA and tcdB. Of 52 (43.3%) with tcdB and truncated tcdA (tcdA-/tcdB+), all were ribotype 017 and none had binary toxin or tcdC deletion. Eighteen (15%) toxigenic isolates harbored binary toxins (cdtA and cdtB) and all had tcdC deletion, including Δ39 (C184T) deletion (14 isolates), Δ18 in-frame deletion (3 isolates), and Δ18 (Δ117A) deletion (1 isolate). Eleven of 14 isolates with Δ39 (C184T) deletion belonged to the ribotype 078 family, including ribotype 127 (6 isolates), ribotype 126 (4 isolates), and ribotype 078 (1 isolate). Among 8 patients with consecutive C. difficile isolates, these isolates from 6 (75%) patients were identical, irrespective of the presence or absence of diarrhea, suggestive of persistent fecal carriage or colonization. In conclusion in southern Taiwan, ribotype 017 isolates with a tcdA-/tcdB+ genotype were not uncommon and of C. difficile isolates with binary toxin, the ribotype 078 family was predominant.

Propensity score-matched analysis comparing the therapeutic efficacies of cefazolin and extended-spectrum cephalosporins as appropriate empirical therapy in adults with community-onset Escherichia coli, Klebsiella spp. and Proteus mirabilis bacteraemia

In this study, the therapeutic efficacy of cefazolin was compared with that of extended-spectrum cephalosporins (ESCs) (cefotaxime, ceftriaxone and ceftazidime) as appropriate empirical therapy in adults with community-onset monomicrobial bacteraemia caused by Escherichia coli, Klebsiella spp. or Proteus mirabilis (EKP). Compared with cefazolin-treated patients (n = 135), significantly higher proportions of patients in the ESC treatment group (n = 456) had critical illness at bacteraemia onset (Pitt bacteraemia score ≥4) and fatal co-morbidities (McCabe classification). Of the 591 patients, 121 from each group were matched using propensity score matching (PSM) based on the following independent predictors of 28-day mortality: fatal co-morbidities (McCabe classification); Pitt bacteraemia score ≥4 at bacteraemia onset; initial syndrome of septic shock; and bacteraemia due to pneumonia. After appropriate PSM, no significant differences were observed in the early clinical failure rate (10.7% vs. 7.4%; P = 0.37), the proportion of critical illness (Pitt bacteraemia score ≥4) (0% vs. 0%; P = 1.00) and defervescence (52.6% vs. 42.6%; P = 0.13) on Day 3 between the cefazolin and ESC treatment groups. Similarly, no significant differences were observed in the mean of time to defervescence (4.1 days vs. 4.9 days; P = 0.15), late clinical failure rate (18.2% vs. 10.7%; P = 0.10) and 28-day crude mortality rate (0.8% vs. 3.3%; P = 0.37) between the two groups. These data suggest that the efficacy of cefazolin is similar to that of ESCs when used as appropriate empirical antimicrobial treatment for community-onset EKP bacteraemia.

Zoonotic potential of the Clostridium difficile RT078 family in Taiwan

Clostridium difficile is the major cause of nosocomial diarrhea. We have previously demonstrated that in southern Taiwan, severe C. difficile-associated diarrhea (CDAD) cases were due to the C. difficile RT 126 strain infection, indicating the arrival of an epidemic C. difficile clone in southern Taiwan. RT126 has a close genetic relationship with RT078. However, the RT078 family is the predominant strain of C. difficile in animals worldwide, particularly in swine. In this study, we surveyed C. difficile strains isolated from swine at several farms in Taiwan from August 2011 to March 2015. We found that all swine strains, namely RT078 (32.5%, 37 of 114), RT126 (28.9%, 33 of 114) and RT127 (37.7%, 43 of 114), belonged to the toxigenic RT078 family. All strains had high gyrA mutation rate (57.9%, 66/114), which was linked to quinolone resistance. Notably, Rep-PCR revealed that 3 RT078 animal strains had the same fingerprint as human RT078 clinical isolates; their phylogenic relationship was closely related to the whole gene sequences of tcdB, thus suggesting zoonotic potential for C. difficile infection in Taiwan.

Antimicrobial susceptibility of clinical Enterobacteriaceae isolates at the emergency department in a regional hospital: A threat of extended spectrum beta-lactamase-producers among nursing home residents

BACKGROUND/PURPOSE

The prevalence of extended spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae in nursing home residents has rarely been reported in Taiwan.

METHODS

A retrospective study was performed at medical wards of a district hospital at southern Taiwan between July 2009 and June 2011. Patients were included if they were older than 18 years, admitted via the emergency department, and their blood, sputum, or urine culture revealed the growth of Escherichia coli, Klebsiella pneumoniae, or Proteus mirabilis. From each patient only the first isolate from the infection site was included. Antimicrobial susceptibility was determined using the disc diffusion method.

RESULTS

Overall, 827 patients were included, with 354 (42.8%) coming from the community and 473 (57.2%) referred from a nursing home. Of the isolates acquired in nursing home, 45.5% (215/473) harbored ESBL. By contrast, 20.6% (73) of 354 isolates acquired in the community exhibited the ESBL production phenotype (p < 0.001). Of the isolates obtained from blood, urine, or sputum, 28.2% (37/131), 36.0% (208/578), or 36.4% (43/118) harbored ESBL, respectively, whereas 41% (211) of 515 E. coli isolates, 34.3% (72) of 210 K. pneumoniae, and 4.9% (5) of 102 P. mirabilis had ESBL. In general, the isolates from a nursing home or those with ESBL had lower antimicrobial susceptibility rates than those from the community or those without ESBL production. Only amikacin, piperacillin/tazobactam, ertapenem, and imipenem/meropenem were active against >90% Enterobacteriaceae isolates, irrespective of ESBL production.

CONCLUSION

ESBL production was common among clinical Enterobacteriaceae isolates, especially E. coli or those isolated from nursing home residents.

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.

Proton-Pump Inhibitor Exposure Aggravates Clostridium difficile-Associated Colitis: Evidence From a Mouse Model

BACKGROUND

Clostridium difficile is currently the leading cause of infectious diarrhea in hospitalized patients. In addition to the infection due to toxigenic C. difficile in the gastrointestinal tract of susceptible hosts, other predisposing factors for C. difficile infection (CDI) are identified, including advanced age, a prolonged hospital stay, and use of acid-suppressive drugs. Of note, exposure to gastric acid-reducing agents, such as H2 blockers and proton pump inhibitors (PPIs), remains a controversial risk factor, and has been associated with CDI in some studies but not in others. A mouse model of antibiotic-associated clostridial colitis was established to examine the role of PPIs for CDI.

MATERIALS AND METHODS

A mouse model of antibiotic-associated clostridial colitis was set up. NF-κB reporter mice were used to address the in vivo spatial and temporal inflammatory patterns of C. difficile-associated colitis. Serum levels of lipopolysaccharide and dextran-FITC were measured to reflect the barrier permeability of affected intestines.

RESULTS

Mice with CDI that were exposed to PPI exhibited greater losses of stool consistency and body and cecal weights than those that were not exposed to PPI. Further, more neutrophilic infiltrations, epithelial damage, and inflammatory cytokine expression were noted in colon specimens of the mice with PPI exposure. More-evident inflammatory responses were detected by in vivo imaging of NF-κB reporter mice with CDI that were exposed to PPI. Gut barrier permeability was increased to a greater extent, as reflected by higher serum levels of lipopolysaccharide and dextran-FITC in mice with CDI that were exposed to PPI.

CONCLUSIONS

Our mouse model demonstrates that PPI exposure increases the severity of intestinal inflammation in mice with C. difficile-associated colitis.