Genome characterization of a novel binary toxin-positive strain of Clostridium difficile and comparison with the epidemic 027 and 078 strains

Abstract Background Clostridium difficile is an anaerobic Gram-positive spore-forming gut pathogen that causes antibiotic-associated diarrhea worldwide. A small number of C. difficile strains express the binary toxin (CDT), which is generally found in C. difficile 027 (ST1) and/or 078 (ST11) in clinic. However, we isolated a binary toxin-positive non-027, non-078 C. difficile LC693 that is associated with severe diarrhea in China. The genotype of this strain was determined as ST201. To understand the pathogenesis-basis of C. difficile ST201, the strain LC693 was chosen for whole genome sequencing, and its genome sequence was analyzed together with the other two ST201 strains VL-0104 and VL-0391 and compared to the epidemic 027/ST1 and 078/ST11 strains. Results The project finally generated an estimated genome size of approximately 4.07 Mbp for strain LC693. Genome size of the three ST201 strains ranged from 4.07 to 4.16 Mb, with an average GC content between 28.5 and 28.9%. Phylogenetic analysis demonstrated that the ST201 strains belonged to clade 3. The ST201 genomes contained more than 40 antibiotic resistance genes and 15 of them were predicted to be associated with vancomycin-resistance. The ST201 strains contained a larger PaLoc with a Tn6218 element inserted than the 027/ST1 and 078/ST11 strains, and encoded a truncated TcdC. In addition, the ST201 strains contained intact binary toxin coding and regulation genes which are highly homologous to the 027/ST1 strain. Genome comparison of the ST201 strains with the epidemic 027 and 078 strain identified 641 genes specific for C. difficile ST201, and a number of them were predicted as fitness and virulence associated genes. The presence of those genes also contributes to the pathogenesis of the ST201 strains. Conclusions In this study, the genomic characterization of three binary toxin-positive C. difficile ST201 strains in clade 3 was discussed and compared to the genomes of the epidemic 027 and the 078 strains. Our analysis identified a number fitness and virulence associated genes/loci in the ST201 genomes that contribute to the pathogenesis of C. difficile ST201

Early versus Delayed Antiretroviral Therapy for HIV and Tuberculosis Co-Infected Patients: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

<div><p>Objective</p><p>To compare important clinical outcomes between early and delayed initiation of antiretroviral therapy (ART) in adults who had a co-infection of human immunodeficiency virus (HIV) and tuberculosis (TB).</p><p>Methods</p><p>We performed a systematic search for relevant publications on PubMed, EMBASE, and the International Clinical Trials Registry Platform. We included randomized controlled trials (RCTs) that compared early ART initiation (within four weeks after anti-TB treatment starting) and delayed ART initiation (after eight weeks but less than twelve weeks of anti-TB treatment starting) in the course of TB treatment. Pooled estimates with corresponding 95% confidence interval (95%CI) were calculated with random-effects model. Sensitivity analysis was performed to investigate the stability of pooled estimates.</p><p>Results</p><p>A meta-analysis was evaluated from six RCTs with 2272 participants. Compared to delayed ART initiation, early ART initiation significantly reduces all-cause mortality in HIV-positive patients with TB [incidence rate ratio (IRR) 0.75, 95%CI 0.59 to 0.95; I² = 0.00%; p = 0.67], even though there is an increased risk for IRD [IRR 2.29, 95%CI 1.81 to 2.91; I²2 = 0.00%; p = 0.56]. Additionally, early ART initiation was not associated with an increased risk for grade 3-4 drug-related adverse events [IRR 0.99, 95%CI 0.83 to 1.18; I² = 0.00%; p = 0.56].</p><p>Conclusions</p><p>Although limited evidence, our results provide support for early ART initiation in the course of anti-TB treatment. However, more well-designed cohort or intervention studies are required to further confirm our findings.</p></div

Characterization of the virulence of a non-RT027, non-RT078 and binary toxin-positive Clostridium difficile strain associated with severe diarrhea

Abstract The expression of the Clostridium difficile binary toxin CDT is generally observed in the RT027 (ST1) and RT078 (ST11) C. difficile isolates, which are associated with severe C. difficile infection (CDI). However, we recently reported that the non-RT027 and non-RT078 C. difficile strain LC693 (TcdA+TcdB+ CDT+, ST201) caused severe diarrhea in a patient in Xiangya Hospital in China. C.difficile LC693 is a member of Clade 3, and in this study, we identified LC693 as RT871 and compared its virulence and pathogenicity to those of C.difficile R20291 (TcdA+TcdB+CDT+, ST1/RT027), UK6 (TcdA+TcdB+CDT+, ST35/RT027), CD630 (TcdA+TcdB+CDT−, ST54, RT012), and 1379 (TcdA+TcdB+CDT−, ST54/RT012), with strain 1379 being an epidemic C.difficile isolate from the same hospital. LC693 displayed a higher sporulation rate than R20291, CD630 or strain 1379. LC693 was comparable to R20291 with respect to spore germination, motility, and biofilm formation, but showed a faster germination rate, higher motility and a higher biofilm formation capability compared to CD630 and strain 1379. The adherence of spores to human gut epithelial cells was similar for all strains.The total toxin release of LC693 was lower than that of R20291, but higher than that of CD630 and strain 1379. Finally, in a mouse model of CDI, LC693 was capable of causing moderate to severe disease. Our findings demonstrate the pathogenicity of non-RT027 and non-RT078 binary toxin-positive C. difficile strains. Furthermore, our data indicate that LC693 may be more virulent than strain 1379, an epidemic strain from the same hospital, and provide the first phenotypic characterization of a non-RT027 and non-RT078 binary toxin-positive ST201 isolate

Characterization of the Virulence of a Non-RT027, Non-RT078 and Binary Toxin-positive Clostridium Difficile Strain Associated with Severe Diarhea

The expression of the Clostridium difficile binary toxin CDT is generally observed in the RT027 (ST1) and RT078 (ST11) C. difficile isolates, which are associated with severe C. difficile infection (CDI). However, we recently reported that the non-RT027 and non-RT078 C. difficile strain LC693 (TcdA+TcdB+ CDT+, ST201) caused severe diarrhea in a patient in Xiangya Hospital in China. C.difficile LC693 is a member of Clade 3, and in this study, we identified LC693 as RT871 and compared its virulence and pathogenicity to those of C.difficile R20291 (TcdA+TcdB+CDT+, ST1/RT027), UK6 (TcdA+TcdB+CDT+, ST35/RT027), CD630 (TcdA+TcdB+CDT−, ST54, RT012), and 1379 (TcdA+TcdB+CDT−, ST54/RT012), with strain 1379 being an epidemic C.difficile isolate from the same hospital. LC693 displayed a higher sporulation rate than R20291, CD630 or strain 1379. LC693 was comparable to R20291 with respect to spore germination, motility, and biofilm formation, but showed a faster germination rate, higher motility and a higher biofilm formation capability compared to CD630 and strain 1379. The adherence of spores to human gut epithelial cells was similar for all strains.The total toxin release of LC693 was lower than that of R20291, but higher than that of CD630 and strain 1379. Finally, in a mouse model of CDI, LC693 was capable of causing moderate to severe disease. Our findings demonstrate the pathogenicity of non-RT027 and non-RT078 binary toxin-positive C. difficile strains. Furthermore, our data indicate that LC693 may be more virulent than strain 1379, an epidemic strain from the same hospital, and provide the first phenotypic characterization of a non-RT027 and non-RT078 binary toxin-positive ST201 isolate

Flow chart of articles identified, screened, assessed and included.

<p>Flow chart of articles identified, screened, assessed and included.</p

Characterization of the Virulence of a Non-RT027, Non-RT078 and Binary Toxin-positive Clostridium Difficile Strain Associated with Severe Diarhea

The expression of the Clostridium difficile binary toxin CDT is generally observed in the RT027 (ST1) and RT078 (ST11) C. difficile isolates, which are associated with severe C. difficile infection (CDI). However, we recently reported that the non-RT027 and non-RT078 C. difficile strain LC693 (TcdA+TcdB+ CDT+, ST201) caused severe diarrhea in a patient in Xiangya Hospital in China. C.difficile LC693 is a member of Clade 3, and in this study, we identified LC693 as RT871 and compared its virulence and pathogenicity to those of C.difficile R20291 (TcdA+TcdB+CDT+, ST1/RT027), UK6 (TcdA+TcdB+CDT+, ST35/RT027), CD630 (TcdA+TcdB+CDT−, ST54, RT012), and 1379 (TcdA+TcdB+CDT−, ST54/RT012), with strain 1379 being an epidemic C.difficile isolate from the same hospital. LC693 displayed a higher sporulation rate than R20291, CD630 or strain 1379. LC693 was comparable to R20291 with respect to spore germination, motility, and biofilm formation, but showed a faster germination rate, higher motility and a higher biofilm formation capability compared to CD630 and strain 1379. The adherence of spores to human gut epithelial cells was similar for all strains.The total toxin release of LC693 was lower than that of R20291, but higher than that of CD630 and strain 1379. Finally, in a mouse model of CDI, LC693 was capable of causing moderate to severe disease. Our findings demonstrate the pathogenicity of non-RT027 and non-RT078 binary toxin-positive C. difficile strains. Furthermore, our data indicate that LC693 may be more virulent than strain 1379, an epidemic strain from the same hospital, and provide the first phenotypic characterization of a non-RT027 and non-RT078 binary toxin-positive ST201 isolate

Funnel plot of the publication bias.

<p>Funnel plot of the publication bias.</p

Forest plot of randomized controlled trials comparing the clinical outcomes of early versus delayed ART initiation.

<p>Forest plot of randomized controlled trials comparing the clinical outcomes of early versus delayed ART initiation.</p