Pre-existing humoral immunity and CD4+ T cell response correlate with cross-reactivity against SARS-CoV-2 Omicron subvariants after heterologous prime-boost vaccination.

BACKGROUND: Information regarding the heterologous prime-boost COVID vaccination has been fully elucidated. The study aimed to evaluate both humoral, cellular immunity and cross-reactivity against variants after heterologous vaccination. METHODS: We recruited healthcare workers previously primed with Oxford/AstraZeneca ChAdOx1-S vaccines and boosted with Moderna mRNA-1273 vaccine boost to evaluate the immunological response. Assay used: anti-spike RBD antibody, surrogate virus neutralizing antibody and interferon-γ release assay. RESULTS: All participants exhibited higher humoral and cellular immune response after the booster regardless of prior antibody level, but those with higher antibody level demonstrated stronger booster response, especially against omicron BA.1 and BA.2 variants. The pre-booster IFN-γ release by CD4+ T cells correlates with post-booster neutralizing antibody against BA.1 and BA.2 variant after adjustment with age and gender. CONCLUSIONS: A heterologous mRNA boost is highly immunogenic. The pre-existing neutralizing antibody level and CD4+ T cells response correlates with post-booster neutralization reactivity against the Omicron variant.

Potentially hypervirulent Clostridium difficile PCR ribotype 078 lineage isolates in pigs and possible implications for humans in Taiwan.

Clostridium difficile is a human and animal pathogen. Recently, the incidence of community-acquired C. difficile infection has increased, and many studies have indicated that C. difficile might be food-borne. The correlation between C. difficile infection in humans and in animals has been a topic of debate. The objective of this study was to determine the genetic relatedness of C. difficile from human and pigs in Taiwan. We investigated the molecular epidemiology of C. difficile in healthy humans and pigs from 2011 to 2015. The isolation rate of C. difficile from pigs in 13 commercial farms was 49% (100/204), and a high proportion of hypervirulent (C. difficile carrying tcdA, tcdB, and cdtA/B genes and a 39-bp deletion in the tcdC gene) ribotype 078 lineage isolates (90%, 90/100; including 078, 126, 127, and 066-like isolates) were identified. In addition, the C. difficile ribotype 127 isolates from pigs typically exhibited moxifloxacin resistance (37/43; 86%). In healthy humans, the isolation rate was 4.3% (3/69), and all healthy human isolates were non-toxigenic. In particular, we compared the porcine isolates with two patient strains (ribotype 127) obtained from two hospitals in central Taiwan. The multilocus variable number tandem repeat analysis revealed a high genetic relatedness between ribotype 127 from patients and pigs. This study indicated that isolates of the ribotype 078 lineage, and especially ribotype 127, were widely distributed in pig farms and showed a high frequency of moxifloxacin resistance. The closely related ribotype 127 from patients and pigs may have had a common origin or low diversity. In conclusion, C. difficile ribotype 127 is a noteworthy pathogen in pigs and poses a potential public health threat.

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.

Clostridium difficile ribotype 126 in southern Taiwan: a cluster of three symptomatic cases.

INTRODUCTION: Several virulent Clostridium difficile clones, designated as polymerase chain reaction (PCR) ribotypes 017, 027, or 078, are well recognized in western countries. However, the ribotype distribution of clinical C. difficile isolates in Taiwan remains unclear. METHOD: Between 2010 and 2012, we identified three patients with C. difficile-associated diarrhea (CDAD) at a hospital in southern Taiwan. The C. difficile strains isolated from these patients were further characterized by PCR detection of tcdA, tcdB, tcdC, cdtA, and cdtB, toxinotyping, multilocus sequence typing, ribotyping and repetitive-based PCR. RESULTS: Three C. difficile strains harbored tcdCΔ39 and belonged to multilocus sequence typing 11 (ST11), toxinotype V, and ribotype 126 (a ribotype 078-like clone). Notably, one patient developed pseudomembranous colitis and recurrent CDAD. These three isolates were noted between January 2012 and June 2012 and were identical, as evidenced by repetitive sequence-based PCR, suggestive of case clustering. CONCLUSION: A hypervirulent C. difficile clone, ribotype 126, causing pseudomembranous colitis and recurrent CDAD, is present in southern Taiwan.

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.

Age and prior vaccination determine the antibody level in children with primary SARS-CoV-2 Omicron infection.

BACKGROUND: Protection against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) reinfection relies on immunity generated after primary infection. However, humoral immunity following primary infection with the Omicron variant is not well understood. METHODS: We prospectively recruited children <19 years with virologically-confirmed SARS-CoV-2 infection at National Cheng Kung University Hospital from February 2022 to September 2022 during the first wave of Omicron BA.2 outbreak in Taiwan. Serum samples were collected one month after acute infection to measure anti-spike protein receptor binding domain antibody levels and surrogate virus neutralizing antibody (NAb) levels against wild type disease and variants. RESULTS: Of the 164 patients enrolled, most were under 5 years (65.2%) with a diagnosis of upper respiratory tract infection. Children under 6 months with maternal coronavirus disease 2019 (COVID-19) vaccination had higher levels of both anti-SARS-CoV-2 spike antibody (119.0 vs 27.4 U/ml, p < 0.05) and anti-wild type NAb (56.9% vs 27.6% inhibition, p = 0.001) than those without. Children aged 5-12 years with prior vaccination had higher anti-spike antibody, anti-wild type, and anti-Omicron BA.2 NAb levels than those without (all p < 0.05). In previously naïve children without maternal or self-vaccination, those 6 months to 2 years had the highest antibody levels. Multivariable linear regression analysis showed age was the only independent factor associated with antibody level. CONCLUSIONS: In our study, children aged 6 months to 2 years have the highest antibody responses to SARS-CoV-2 Omicron variant infection. Age and prior vaccination are the main factors influencing the immunogenicity of SARS-CoV-2 infection.

Lewis Acid Probe for Basicity of Sulfide Electrolytes Investigated by 11B Solid-State NMR.

Sulfide-based solid-state lithium-ion batteries (SSLIB) have attracted a lot of interest globally in the past few years for their high safety and high energy density over the traditional lithium-ion batteries. However, sulfide electrolytes (SEs) are moisture-sensitive which pose significant challenges in the material preparation and cell manufacturing. To the best of our knowledge, there is no tool available to probe the types and the strength of the basic sites in sulfide electrolytes, which is crucial for understanding the moisture stability of sulfide electrolytes. Herein, we propose a new spectral probe with the Lewis base indicator BBr3 to probe the strength of Lewis basic sites on various sulfide electrolytes by 11B solid-state NMR spectroscopy (11B-NMR). The active sulfur sites and the corresponding strength of the sulfide electrolytes are successfully evaluated by the proposed Lewis base probe. The probed strength of the active sulfur sites of a sulfide electrolyte is consistent with the results of DFT (density functional theory) calculation and correlated with the H2S generation rate when the electrolyte was exposed in moisture atmosphere. This work paves a new way to investigate the basicity and moisture stability of the sulfide electrolytes.

Novel metal peroxide nanoboxes restrain Clostridioides difficile infection beyond the bactericidal and sporicidal activity.

Clostridioides difficile spores are considered as the major source responsible for the development of C. difficile infection (CDI), which is associated with an increased risk of death in patients and has become an important issue in infection control of nosocomial infections. Current treatment against CDI still relies on antibiotics, which also damage normal flora and increase the risk of CDI recurrence. Therefore, alternative therapies that are more effective against C. difficile bacteria and spores are urgently needed. Here, we designed an oxidation process using H2O2 containing PBS solution to generate Cl- and peroxide molecules that further process Ag and Au ions to form nanoboxes with Ag-Au peroxide coat covering Au shell and AgCl core (AgAu-based nanoboxes). The AgAu-based nanoboxes efficiently disrupted the membrane structure of bacteria/spores of C. difficile after 30-45 min exposure to the highly reactive Ag/Au peroxide surface of the nano structures. The Au-enclosed AgCl provided sustained suppression of the growth of 2 × 107 pathogenic Escherichia coli for up to 19 days. In a fecal bench ex vivo test and in vivo CDI murine model, biocompatibility and therapeutic efficacy of the AuAg nanoboxes to attenuate CDI was demonstrated by restoring the gut microbiota and colon mucosal structure. The treatment successfully rescued the CDI mice from death and prevented their recurrence mediated by vancomycin treatment. The significant outcomes indicated that the new peroxide-derived AgAu-based nanoboxes possess great potential for future translation into clinical application as a new alternative therapeutic strategy against CDI.

Hypervirulent Clostridioides difficile RT078 lineage isolates from the river: A potential reservoir for environmental transmission.

This is the first report to discover Clostridiodes difficile (C. difficile) ribotype RT126 and RT598 (both ribotypes belong to RT078-lineage) in a river water system in southern Taiwan. Fluoroquinolone resistance was also found. The connection between clinical isolates and those from the environment needs further investigation.

Effect of Doxycycline in Decreasing the Severity of Clostridioides difficile Infection in Mice.

Background: Doxycycline possesses antibacterial activity against Clostridioides difficile and anti-inflammatory effects. Materials and Methods: The influence of doxycycline on the development of CDI was studied in an established animal model of CDI using C57BL/6 mice. Results: Mice intraperitoneally administered doxycycline had higher cecum weight (1.3 ± 0.1 vs. 0.5 ± 0.1 g; p < 0.001) and less body weight reduction (0.7 ± 0.5 g vs. -17.4 ± 0.2 g; p < 0.001) than untreated mice infected with C. difficile. Oral doxycycline, metronidazole, or vancomycin therapy resulted in less body weight reduction in mice with CDI than in untreated mice (1.1 ± 0.1 g, 1.3 ± 0.2 g, 1.2 ± 0.1 g, vs. 2.9 ± 0.3 g; p < 0.001). Doxycycline therapy led to lower expression levels of inflammatory cytokines, such as macrophage inflammatory protein-2 (0.4 ± 0.1 vs. 2.9 ± 1.3, p = 0.02), and higher levels of zonula occludens-1 (1.2 ± 0.1 vs. 0.8 ± 0.1, p = 0.02) in colonic tissues than in untreated mice. Conclusions: Concurrent intraperitoneal administration of doxycycline and oral C. difficile challenge does not aggravate the disease severity of CDI, and oral doxycycline may be a potential therapeutic option for 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.

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.

Severe Clostridium difficile infections in intensive care units: Diverse clinical presentations.

BACKGROUND: Clostridium difficile infections (CDIs) cause significant mortality and morbidity. Critically ill patients are susceptible to CDIs and tend to have severe CDIs, and their clinical presentations are not merely diarrhea. MATERIALS AND METHODS: From September 2017 to March 2018, the adults with CDIs in the ICUs were included. Fecal specimens with positive results of glutamate dehydrogenase assay were cultured for C. difficile, and toxinotyping and ribotyping for available C. difficile isolates were done. The CDI cases were categorized into the diarrheal group and ileus group. Difficult-to-treat cases with the presentations of life-threatening complications (bowel perforation or bacteremia), toxic megacolon, and refractory diarrhea, were analyzed. RESULTS: Totally 23 cases, including 6 cases of ileus and 17 of diarrhea, were included. Overall, the incidence of CDI in the ICUs was 10.7 cases per 10,000 patient-days. The ileus group tended to have more severe presentation, shorter ICU stay, higher ICU mortality, and receive initial intravenous metronidazole therapy. Severe and fulminant CDIs accounted for 65.2% (15 cases). The ICU mortality rate was 39.1%, but only one death was directly related to CDI (4.3%). Of nine (39.1%) difficult-to-treat cases, there was only one isolate of RT611 with tcdC deletion and cdtA/cdtB from a case with toxic megacolon. No hypervirulent isolates of RT027 or 078 were detected. CONCLUSION: Severe CDIs in the ICU were not rare. Clinicians should be aware of abdominal symptoms and signs other than diarrhea, such as ileus, to make timely diagnosis and management of CDI.

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.

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.

Risk factors of Clostridium difficile-associated diarrhea in hospitalized adults: Vary by hospitalized duration.

BACKGROUND: Clostridium difficile is the leading cause of nosocomial infectious diarrhea. Hospitalized patients were at risk of C. difficile-associated diarrhea (CDAD). However the risk factors of CDAD in patients with different hospitalization period are not clear. MATERIAL AND METHODS: A prospective investigation was conducted in medical wards of a district hospital in southern Taiwan, from January 2011 to January 2013. We arbitrary divided patients into two groups: hospitalized for at most 14 days and 15-30 days, and analyzed their risk factors for CDAD. RESULTS: Overall 451 patients were enrolled. The multivariable analysis of 19 (8.0%) patients developing CDAD within 14 days' hospital stay and 216 patients hospitalized for ≤ 14 days without CDAD showed malignancy (odds ratio [OR] 7.15, 95% confidence interval [CI] 1.82-28.09; P = 0.005), prior cephalosporin (OR 10.8, 95% CI 1.3-93.9; P = 0.03) and proton pump inhibitor (PPI; OR 7.1, 95% CI 2.1-24.7; P = 0.002) therapy were independently related to CDAD (Table 3), but hypertension (OR 0.2, 95% CI 0.1-0.7; P = 0.01) was reversely related to CDAD. However, of 9 (4.2%) patients developing CDAD later (15-30 days' hospital stay) and 207 patients with longer hospitalization (15-30 days) but free of CDAD, malignancy (OR 14.0, 95% CI 1.6-124.9; P = 0.02) and underlying diabetes mellitus (OR 20.5, 95% CI 2.9-144.9; P = 0.002) were independent risk factors of CDAD. CONCLUSION: Risk factors for CDAD among hospitalized patients varied by the duration of hospital stay. Intervention strategies to prevent CDAD may be different in terms of hospital stay duration.

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

[This corrects the article DOI: 10.3389/fimmu.2021.691039.].

Vancomycin-Loaded Nanoparticles Enhance Sporicidal and Antibacterial Efficacy for Clostridium difficile Infection.

Current antibiotic treatments fail to eliminate the Clostridium difficile (C. difficile) spores and induce dysbiosis and intestinal inflammation via off-target effect, which causes refractory C. difficile infection raise an unmet need for a spore-specific antimicrobial treatment. We developed a sporicidal and antimicrobial vancomycin-loaded spore-targeting iron oxide nanoparticle (van-IONP) that selectively binds to C. difficile spores. Cryo-electron microscopy showed that vancomycin-loaded nanoparticles can target and completely cover spore surfaces. They not only successfully delayed the germination of the spores but also inhibited ∼50% of vegetative cell outgrowth after 48 h of incubation. The van-IONPs also inhibited the interaction of spores with HT-29 intestinal mucosal cells in vitro. In a murine model of C. difficile infection, the van-IONP significantly protected the mice from infected by C. difficile infection, reducing intestinal inflammation, and facilitated superior mucosal viability compared with equal doses of free vancomycin. This dual-function targeted delivery therapy showed advantages over traditional therapeutics in treating C. difficile infection.

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.