The incidence and drug resistance of Clostridium difficile infection in Mainland China: a systematic review and meta-analysis

Genomic epidemiology of Clostridioides difficile sequence type 35 reveals intraspecies and interspecies clonal transmission

Clostridioides difficile sequence type (ST) 35 has been found in humans and animals worldwide. However, its genomic epidemiology and clonal transmission have not been explored in detail. In this study, 176 C. difficile ST35 isolates from six countries were sequenced. Genomic diversity, clonal transmission and epidemiological data were analyzed. Sporulation and virulence capacities were measured. Four ribotypes (RT) were identified including RT046 (97.2%), RT656 (1.1%), RT427 (0.6%), and RT AI-78 (1.1%). Phylogenetic analysis of 176 ST35 genomes, along with 50 publicly available genomes, revealed two distinctive lineages without time-, region-, or source-dependent distribution. However, the distribution of antimicrobial resistance genes differed significantly between the two lineages. Nosocomial and communal transmission occurred in humans with the isolates differed by ≤ two core-genome single-nucleotide polymorphism (cgSNPs) and clonal circulation was found in pigs with the isolates differed by ≤ four cgSNPs. Notably, interspecies clonal transmission was identified among three patients with community acquired C. difficile infection and pigs with epidemiological links, differed by ≤ nine cgSNPs. Toxin B (TcdB) concentrations were significantly higher in human isolates compared to pig isolates, and ST35 isolates exhibited stronger sporulation capacities than other STs. Our study provided new genomic insights and epidemiological evidence of C. difficile ST35 intraspecies and interspecies clonal transmission, which can also be facilitated by its strong sporulation capacity.

Antimicrobial susceptibilities, resistance mechanisms and molecular characteristics of toxigenic Clostridioides difficile isolates in a large teaching hospital in Chongqing, China

OBJECTIVES

Clostridioides difficile ranks among the primary sources of healthcare-related infections and diarrhoea in numerous nations. We evaluated the drug susceptibility and resistance mechanisms of C. difficile isolates from a hospital in Chongqing, China, and identified resistance rates and resistance mechanisms that differed from previous findings.

METHODS

The toxin genes and drug resistance genes of clinical strains were detected using Polymerase Chain Reaction (PCR), and these strains were subjected to Multilocus Sequence Typing (MLST). The agar dilution technique was employed for assessing susceptibility of antibiotics. Clinical data collection was completed through a review of electronic medical records.

RESULTS

A total of 67 strains of toxin-producing C. difficile were detected. All C. difficile isolates demonstrated susceptibility to both metronidazole and vancomycin. However, resistance was observed in 8.95%, 16.42%, 56.72%, 56.72%, 31.34% and 5.97% of the isolates for tigecycline, tetracycline, clindamycin, erythromycin, moxifloxacin and rifampin, respectively. Among the strains with toxin genotypes A + B + CDT - and belonging to the ST3, six strains exhibited reduced susceptibility to tigecycline (MIC=0.5mg/L) and tetracycline (MIC=8mg/L). The tetA(P) and tetB(P) genes were present in these six strains, but were absent in tetracycline-resistant strains. Resistance genes (ermB, tetM, tetA(P) and tetB(P)) and mutations (in gyrA, gyrB, and rpoB) were identified in resistant strains.

CONCLUSIONS

In contrast to prior studies, we found higher proportions of ST3 isolates with decreased tigecycline sensitivity, sharing similar resistance patterns and resistance genes. In the resistance process of tigecycline and tetracycline, the tetA(P) and tetB(P) genes may play a weak role.

Development and evaluation of a rapid visual loop-mediated isothermal amplification assay for the tcdA gene in Clostridioides difficile detection

Background

The tcdA gene codes for an important toxin produced by Clostridioides difficile (C. difficile), but there is currently no simple and cost-effective method of detecting it. This article establishes and validates a rapid and visual loop-mediated isothermal amplification (LAMP) assay for the detection of the tcdA gene.

Methods

Three sets of primers were designed and optimized to amplify the tcdA gene in C. difficile using a LAMP assay. To evaluate the specificity of the LAMP assay, C. difficile VPI10463 was used as a positive control, while 26 pathogenic bacterial strains lacking the tcdA gene and distilled water were utilized as negative controls. For sensitivity analysis, the LAMP assay was compared to PCR using ten-fold serial dilutions of DNA from C. difficile VPI10463, ranging from 207 ng/µl to 0.000207 pg/µl. The tcdA gene of C.difficile was detected in 164 stool specimens using both LAMP and polymerase chain reaction (PCR). Positive and negative results were distinguished using real-time monitoring of turbidity and chromogenic reaction.

Results

At a temperature of 66 °C, the target DNA was successfully amplified with a set of primers designated, and visualized within 60 min. Under the same conditions, the target DNA was not amplified with the tcdA12 primers for 26 pathogenic bacterial strains that do not carry the tcdA gene. The detection limit of LAMP was 20.700 pg/µl, which was 10 times more sensitive than that of conventional PCR. The detection rate of tcdA in 164 stool specimens using the LAMP method was 17% (28/164), significantly higher than the 10% (16/164) detection rate of the PCR method (X2 = 47, p < 0.01).

Conclusion

LAMP method is an effective technique for the rapid and visual detection of the tcdA gene of C. difficile, and shows potential advantages over PCR in terms of speed, simplicity, and sensitivity. The tcdA-LAMP assay is particularly suitable for medical diagnostic environments with limited resources and is a promising diagnostic strategy for the screening and detection of C. difficile infection in populations at high risk.

Fighting against Clostridioides difficile infection: Current medications

Clostridioides difficile (formerly Clostridium difficile) has been regarded as an 'urgent threat' and a significant global health problem, as life-threatening diarrhoea and refractory recurrence are common in patients with C. difficile infection (CDI). Unfortunately, the available anti-CDI drugs are limited. Recent guidelines recommend fidaxomicin and vancomycin as first-line drugs to treat CDI, bezlotoxumab to prevent recurrence, and faecal microbiota transplantation for rescue treatment. Currently, researchers are investigating therapeutic antibacterial drugs (e.g. teicoplanin, ridinilazole, ibezapolstat, surotomycin, cadazolid, and LFF571), preventive medications against recurrence (e.g. Rebyota, Vowst, VP20621, VE303, RBX7455, and MET-2), primary prevention strategies (e.g. vaccine, ribaxamase, and DAV132) and other anti-CDI medications in the preclinical stage (e.g. Raja 42, Myxopyronin B, and bacteriophage). This narrative review summarises current medications, including newly marketed drugs and products in development against CDI, to help clinicians treat CDI appropriately and to call for more research on innovation.

Toxin genotypes, antibiotic resistance and their correlations in Clostridioides difficile isolated from hospitals in Xi'an, China

BACKGROUND

Clostridioides difficile is the main pathogen of antimicrobial-associated diarrhoea and health care facility-associated infectious diarrhoea. This study aimed to investigate the prevalence, toxin genotypes, and antibiotic resistance of C. difficile among hospitalized patients in Xi'an, China.

RESULTS

We isolated and cultured 156 strains of C. difficile, representing 12.67% of the 1231 inpatient stool samples collected. Among the isolates, tcdA + B + strains were predominant, accounting for 78.2% (122/156), followed by 27 tcdA-B + strains (27/156, 17.3%) and 6 binary toxin gene-positive strains. The positive rates of three regulatory genes, tcdC, tcdR, and tcdE, were 89.1% (139/156), 96.8% (151/156), and 100%, respectively. All isolates were sensitive to metronidazole, and the resistance rates to clindamycin and cephalosporins were also high. Six strains were found to be resistant to vancomycin.

CONCLUSION

Currently, the prevalence rate of C. difficile infection (CDI) in Xi'an is 12.67% (156/1231), with the major toxin genotype of the isolates being tcdA + tcdB + cdtA-/B-. Metronidazole and vancomycin were still effective drugs for the treatment of CDI, but we should pay attention to antibiotic management and epidemiological surveillance of CDI.

[Analysis of Clostridioides difficile infection characteristics and risk factors in patients hospitalized for diarrhea in 3 university hospitals in a mid-south city of China]

OBJECTIVE

To investigate the characteristics of Clostridioides difficile infection (CDI) in patients hospitalized for diarrhea and analyze the risk factors for CDI.

METHODS

Stool samples were collected from 306 patients with diarrhea hospitalized in 3 university hospitals in a mid-south city of China from October to December, 2020. C. difficile was isolated by anaerobic culture, and qRT-PCR was used to detect the expressions of toxin A (tcdA) and B (tcdB) genes and the binary toxin genes (cdtA and cdtB). Multilocus sequence typing (MLST) was performed for the isolated strains without contaminating strains as confirmed by 16S rDNA sequencing. Etest strips were used to determine the drug resistance profiles of the isolated strains, and the risk factors of CDI in the patients were analyzed.

RESULTS

CDI was detected in 25 (8.17%) out of the 306 patients. All the patients tested positive for tcdA and tcdB but negative for the binary toxin genes. Seven noncontaminated C. difficile strains with 5 ST types were isolated, including 3 ST54 strains and one strain of ST129, ST98, ST53, and ST631 types each, all belonging to clade 1 and sensitive to metronidazole and vancomycin. Hospitalization within the past 6 months (OR= 3.675; 95% CI: 1.405-9.612), use of PPIs (OR=7.107; 95% CI: 2.575-19.613), antibiotics for ≥1 week (OR=7.306; 95% CI: 2.274-23.472), non-steroidal anti-inflammatory drugs (OR=4.754; 95% CI: 1.504-15.031) in the past month, and gastrointestinal disorders (OR=5.050; 95% CI: 1.826-13.968) were all risk factors for CDI in the patients hospitalized for diarrhea.

CONCLUSION

The CDI rate remains low in the hospitalized patients with diarrhea in the investigated hospitals, but early precaution measures are recommended when exposure to the risk factors is reported to reduce the risk of CDI in the hospitalized patients.

Antimicrobial Resistance and Associated Risk Factors for Clostridium difficile in Patients Attending Tertiary Care Settings

To determine the incidence of antimicrobial-resistant emerging pathogens, Clostridium difficile, and its associated risk factors in tertiary care setups of Pakistan. This cross-sectional prospective study was conducted from January 2019 to December 2020, to determine the prevalence and antimicrobial resistance patterns of C. difficile strains isolated from 450 stool specimens of patients suffering from diarrhea hospitalized in tertiary care hospitals in Peshawar, Pakistan. The stool samples of the patients were processed for culture and detection of toxin A and toxin B by enzyme-linked immunosorbent assay (ELISA) and tpi PCR. The drug sensitivity test was performed for antibiotics including ampicillin, cefixime, cefepime, amoxicillin, nalidixic acid, sulpha/TMP (SXT), chloramphenicol, metronidazole, vancomycin, ciprofloxacin, levofloxacin, and imipenem. Of 450 stool specimens, 108 (24%) were positive for C. difficile by stool culture, whereas 115 (25.5%) were only positive for C. difficile toxins based on ELISA and PCR (128 (28.6%). Of 108, 90.7% (n = 98) isolates were resistant to one antibiotic, and 90 (83.4%) were resistant to three or more antimicrobials. The highest resistance rates were found against penicillin (83.3%) followed by amoxicillin (70%), nalidixic acid (61%), and metronidazole (38%), and the lowest resistance was found against vancomycin (6.4%) and imipenem (3.7%). CDI was statistically significantly correlated with increased age, use of antibiotics, abdominal surgeries, use of proton pump inhibitors and H2a, and presence of comorbidities. The high frequency of C. difficile in Peshawar, Pakistan, indicates that CDI is an important nosocomial infection in different hospitals. The results will be helpful for clinicians to redesign control and therapeutic strategies in hospitals.

Analysis of risk factors for community-acquired Clostridioides difficile diarrhea in children: a case-control study in Chenzhou, China

Background

Most previous studies on Clostridium difficile infection (CDI) mainly focused on adults with underlying diseases or critical illnesses. However, the number of CDI cases in children has also significantly increased, especially the growth of community-acquired CDI, which has attracted attention. This study was conducted to examine the toxin gene characteristics and the risk factors associated with community-acquired CDI (CA-CDI) in children with diarrhea.

Methods

Children with diarrhea before admission or within 48 hours of hospitalization were included in the study. Stool samples were collected from children with community-acquired diarrhea who were treated at the Children's Hospital of the First People's Hospital of Chenzhou, China from June of 2021 to June of 2022. Fluorescence real-time polymerase chain reaction was utilized to detect Clostridioides difficile (CD) toxins A (tcdA) and B (tcdB) genes as well as binary toxin gene A (cdtA) and B (cdtB) in the specimens cultured for CD. Each child with CA-CDI was matched with four control children of the same sex, age, and place of residence. Necessary clinical data were extracted from the hospital's electronic medical record system. Then, a multivariate conditional logistic regression analysis was applied to identify potential risk factors for CA-CDI.

Results

Sixteen (8.3%) of the 193 stool specimens who tested positive for CD were selected for the case group, and their matching 64 control patients were in the study cohort. The breakdown of the CD genotypes of the 16 positive cases were follows: 14 (tcdA+ and tcdB+) (7.25%) and 2 (tcdA+ and tcdB-) (1.04%). The cdtA and cdtB binary toxin genes were negative in all. The results of multivariate conditional logistic regression analysis identified antibiotic use within the previous month [odds ratio (OR) =5.13; 95% confidence interval (CI): 1.65-15.91] and non-breastfeeding (OR =4.89; 95% CI: 1.11-21.53) as independent risk factors for CDI in pediatric patients experiencing community-acquired diarrhea.

Conclusions

Children who had been treated with antibiotics and not breastfed were more susceptible to CDI. Therefore, in order to prevent and to control the spread of CD infection, being prudent to the aforementioned high-risk factors is strongly advocated in clinical practice.

An epidemiological surveillance study (2021-2022): detection of a high diversity of Clostridioides difficile isolates in one tertiary hospital in Chongqing, Southwest China

BACKGROUND

Clostridioides difficile is a bacterium that causes antibiotic-associated infectious diarrhea and pseudomembranous enterocolitis. The impact of C. difficile infection (CDI) in China has gained significant attention in recent years. However, little epidemiological data are available from Chongqing, a city located in Southwest China. This study aimed to investigate the epidemiological pattern of CDI and explore the drug resistance of C. difficile isolates in Chongqing.

METHODS

A case-control study was conducted to investigate the clinical infection characteristics and susceptibility factors of C. difficile. The features of the C. difficile isolates were evaluated by testing for toxin genes and using multi-locus sequence typing (MLST). The susceptibility of strains to nine antibiotics was determined using agar dilution technique.

RESULTS

Out of 2084 diarrhea patients, 90 were tested positive for the isolation of toxigenic C. difficile strains, resulting in a CDI prevalence rate of 4.32%. Tetracycline, cephalosporins, hepatobiliary disease, and gastrointestinal disorders were identified as independent risk factors for CDI incidence. The 90 strains were classified into 21 sequence types (ST), with ST3 being the most frequent (n = 25, 27.78%), followed by ST2 (n = 10, 11.11%) and ST37 (n = 9, 10%). Three different toxin types were identified: 69 (76.67%) were A+B+CDT-, 12 (13.33%) were A-B+CDT-, and 9 (10%) were A+B+CDT+. Although substantial resistance to erythromycin (73.33%), moxifloxacin (62.22%), and clindamycin (82.22%), none of the isolates exhibited resistance to vancomycin, tigecycline, or metronidazole. Furthermore, different toxin types displayed varying anti-microbial characteristics.

CONCLUSIONS

The strains identified in Chongqing, Southwest China, exhibited high genetic diversity. Enhance full awareness of high-risk patients with HA-CDI infection, particularly those with gastrointestinal and hepatocellular diseases, and emphasize caution in the use of tetracycline and capecitabine. These findings suggest that a potential epidemic of CDI may occur in the future, emphasizing the need for timely monitoring.

Prevalence and molecular characterization of Clostridioides difficile infection in China over the past 5 years: a systematic review and meta-analysis

OBJECTIVES

The aim of this study was to provide an overview of the prevalence and molecular characteristics of Clostridioides difficile infection (CDI) in China in the past 5 years.

METHODS

A systematic literature review was conducted according to the preferred reporting items for systematic reviews and meta-analyses guidelines. Nine databases were searched for relevant studies published between January 2017 and February 2022. The Joanna Briggs Institute critical appraisal tool was used to assess the quality of included studies, and R software version 4.1.3 was used for data analysis. Funnel plots and Egger regression tests were also performed to assess publication bias.

RESULTS

A total of 50 studies were included in the analysis. The pooled prevalence of CDI in China was 11.4% (2696/26,852). The main circulating C. difficile strains in southern China were ST54, ST3, and ST37, consistent with the overall situation in China. However, the most prevalent genotype in northern China was ST2, which was previously underappreciated.

CONCLUSION

Based on our findings, increased awareness and management of CDI is necessary to reduce the prevalence of CDI in China.

Make It Less difficile: Understanding Genetic Evolution and Global Spread of Clostridioides difficile

Clostridioides difficile is an obligate anaerobic pathogen among the most common causes of healthcare-associated infections. It poses a global threat due to the clinical outcomes of infection and resistance to antibiotics recommended by international guidelines for its eradication. In particular, C. difficile infection can lead to fulminant colitis associated with shock, hypotension, megacolon, and, in severe cases, death. It is therefore of the utmost urgency to fully characterize this pathogen and better understand its spread, in order to reduce infection rates and improve therapy success. This review aims to provide a state-of-the-art overview of the genetic variation of C. difficile, with particular regard to pathogenic genes and the correlation with clinical issues of its infection. We also summarize the current typing techniques and, based on them, the global distribution of the most common ribotypes. Finally, we discuss genomic surveillance actions and new genetic engineering strategies as future perspectives to make it less difficile.

Isolation, molecular typing and antimicrobial resistance of Clostridium difficile in dogs and cats in Lanzhou city of Northwest China

Clostridium difficile infection (CDI) in human and animals belonged usually to antibiotic-associated diarrhea, ranging in severity from mild to life-threatening intestinal tract illnesses. This study aimed to isolation and characterization, toxin genes test, molecular typing, and drug sensitivity of Clostridium difficile (C. difficile) which were isolated from clinical diseased dogs and cats. A total of 247 clinical samples were collected from five animal hospitals in Lanzhou City of Northwest China, of which dogs and cats accounted for 74.9% (185/247) and 25.1% (62/247), respectively. We successfully identified 24 C. difficile strains by 16S rRNA and Matrix-Assisted Laser Desorption/Ionization Time of Fight Mass Spectroscopy (MALDI-TOF-MS). 10.3% (19/185) of dogs and 8.1% (5/62) of cats were positive for C. difficile. Among them, 16 strains were toxic and 8 were non-toxic, with a toxic rate of 57.9% (11/19) in dogs and 100% (5/5) in cats. A total of 10 STs and 10 RTs were identified in this study. The percentages of ST42 (RT106) and ST2 (RT014/LW01) among 16 toxic strains were 41.7 and 12.5%, respectively. However, ST3 (RT001), ST1 (RT027), ST133 (LW04), and ST-UN (LW04) had only one strain. ST42 (RT106) was the most common genotype and RT027 strain was first isolated in China from pets. Antimicrobial susceptibility test showed that isolates were extremely sensitive to vancomycin and metronidazole but were resistant to erythromycin and ciprofloxacin. The drug resistant rates to clindamycin, levofloxacin, moxifloxacin and meropenem were 62.5, 20.8, 16.7, and 8.3%, respectively. In conclusion, C. difficile was quietly prevalent in dogs and cats in Lanzhou city with RT106 and RT014 as the main ribotypes. The CDI in pets should be paying more attention and further studies are needed.

Antibiotic resistance and genomic features of Clostridioides difficile in southwest China

Background

Clostridioides difficile infection (CDI) caused by toxigenic strains leads to antibiotic-related diarrhea, colitis, or even fatal pseudomembranous enteritis. Previously, we conducted a cross-sectional study on prevalence of CDI in southwest China. However, the antibiotics resistance and characteristics of genomes of these isolates are still unknown.

Methods

Antibiotic susceptibility testing with E-test strips and whole genome sequence analysis were used to characterize the features of these C. difficile isolates.

Results

Forty-nine strains of C. difficile were used in this study. Five isolates were non-toxigenic and the rest carried toxigenic genes. We have previously reported that ST35/RT046, ST3/RT001 and ST3/RT009 were the mostly distributed genotypes of strains in the children group. In this study, all the C. difficile isolates were sensitive to metronidazole, meropenem, amoxicillin/clavulanic acid and vancomycin. Most of the strains were resistant to erythromycin, gentamicin and clindamycin. The annotated resistant genes, such as macB, vanRA, vanRG, vanRM, arlR, and efrB were mostly identified related to macrolide, glycopeptide, and fluoroquinolone resistance. Interestingly, 77.55% of the strains were considered as multi-drug resistant (MDR). Phylogenetic analysis based on core genome of bacteria revealed all the strains were divided into clade 1 and clade 4. The characteristics of genome diversity for clade 1 could be found. None of the isolates showed 18-bp deletion of tcdC as RT027 strain as described before, and polymorphism of tcdB showed a high degree of conservation than tcdA gene.

Conclusions

Most of the C. difficile isolates in this study were resistant to macrolide and aminoglycoside antibiotics. Moreover, the MDR strains were commonly found. All the isolates belonged to clade 1 and clade 4 according to phylogenetic analysis of bacterial genome, and highly genomic diversity of clade 1 was identified for these strains.

Influence of Binary Toxin Gene Detection and Decreased Susceptibility to Antibiotics among Clostridioides difficile Strains on Disease Severity: a Single-Center Study

Clostridioides difficile infection (CDI) is the fifth leading cause of death from nonmalignant gastrointestinal disease in the United States. The contribution of resistance to C. difficile-active antibiotics to the outcomes of CDI is unclear. We evaluated the antimicrobial susceptibility of C. difficile isolates in a U.S. hospital and determined associations of clinical variables and binary toxin positivity with antibiotic resistance. C. difficile spores were cultured from fecal specimens of adult patients with CDI for genotyping and antimicrobial susceptibility assay (for clindamycin [CLI], fidaxomicin [FDX], metronidazole [MTZ], moxifloxacin [MXF], tigecycline [TGC], and vancomycin [VAN]). Electronic medical records were reviewed for clinical data extraction. Ninety-seven of 130 (75%) fecal samples grew toxigenic C. difficile in culture. Most of the isolates were tcdA⁺ tcdB⁺ cdtB^- (80.4%), and 18.6% and 1% were tcdA⁺ tcdB⁺ cdtB⁺ and tcdA^-tcdB⁺ cdtB⁺, respectively. Susceptibility to VAN, MTZ, FDX, TGC, MXF, and CLI was 96%, 94%, 100%, 100%, 8%, and 79%, respectively. Six isolates, all cdtB positive and belonging to the 027 ribotype, were resistant to VAN and/or MTZ. Higher MICs were found in isolates with a mutation in the VAN-related resistance gene vanR, but not vanS. In addition, cdtB⁺ isolates exhibited higher MICs of VAN, MTZ, TGC, CLI, and MXF compared to cdtB^- strains. Patients with greater intestinal inflammation or severe disease were more likely to be infected with cdtB⁺ strains. Decreased susceptibility to antibiotics is not directly associated with either severe or recurrent CDI. However, antimicrobial susceptibility of C. difficile is decreased in strains positive for the binary toxin gene.

Development and Clinical Application of a Rapid and Visual Loop-Mediated Isothermal Amplification Test for tetM gene in Clostridioides difficile Strains Cultured from Feces

OBJECTIVES

To develop a rapid and visual loop-mediated isothermal amplification (LAMP) assay targeting the tetM gene in Clostridioides difficile (C. difficile) strains cultured from feces.

METHODS

Primers were designed to recognize the tetM gene in C. difficile by LAMP, using turbidity and visual detection. The sensitivity and specificity of LAMP primers was determined. Besides, We conducted both LAMP and polymerase chain reaction (PCR) for the tcdA, tcdB, cdtA, cdtB, ermB, tetM genes in 300 toxigenic C. difficile strains cultured from feces.

RESULTS

The target DNA was amplified and visualized within 60 minutes at a temperature of 62°C. A total of 26 bacterial strains were found negative for tetM, which manifested high specificity of the primers. The detection limit of LAMP was 36.1 pg/µl, which was 100-fold more sensitive than PCR. The positive rate of tetM in toxigenic C. difficile strains cultured from feces was 93.3% by both LAMP and PCR. The proportion of toxin types in those C. difficile strains was 95.7% for A+B+CDT-, 4% for A-B+CDT-, and 0.3% for A+B+CDT+, respectively.

CONCLUSIONS

This is the first study examining tetM gene in C. difficile strains cultured from feces by LAMP. Its high specificity and sensitivity, as well as visual detection, make the new assay a powerful diagnostic tool for rapid testing.

Akkermansia muciniphila Ameliorates Clostridioides difficile Infection in Mice by Modulating the Intestinal Microbiome and Metabolites

Clostridioides difficile is a common cause of nosocomial infection. Antibiotic-induced dysbiosis in the intestinal microbiota is a core cause of C. difficile infection (CDI). Akkermansia muciniphila plays an active role in maintaining gastrointestinal balance and might offer the protective effects on CDI as probiotics. Here, we investigated the effects and mechanisms of A. muciniphila on CDI. C57BL/6 mice (n = 29) were administered A. muciniphila Muc T (3 × 109 CFUs, 0.2 mL) or phosphate-buffered saline (PBS) by oral gavage for 2 weeks. Mice were pretreated with an antibiotic cocktail and subsequently challenged with the C. difficile strain VPI 10463. A. muciniphila treatment prevented weight loss in mice and reduced the histological injury of the colon. And it also alleviated inflammation and improved the barrier function of the intestine. The administration effects of A. muciniphila may be associated with an increase in short-chain fatty acid production and the maintenance of bile acids' steady-state. Our results provide evidence that administration of A. muciniphila to CDI mice, with an imbalance in the microbial community structure, lead to a decrease in abundance of members of the Enterobacteriaceae and Enterococcaceae. In short, A. muciniphila shows a potential anti-CDI role by modulating gut microbiota and the metabolome.

Prevalence and antimicrobial resistance pattern of Clostridium difficile among hospitalized diarrheal patients: A systematic review and meta-analysis

Background

Clostridium difficile is the leading cause of infectious diarrhea that develops in patients after hospitalization during antibiotic administration. It has also become a big issue in community-acquired diarrhea. The emergence of hypervirulent strains of C. difficile poses a major problem in hospital-associated diarrhea outbreaks and it is difficult to treat. The antimicrobial resistance in C. difficile has worsened due to the inappropriate use of broad-spectrum antibiotics including cephalosporins, clindamycin, tetracycline, and fluoroquinolones together with the emergence of hypervirulent strains.

Objective

To estimate the pooled prevalence and antimicrobial resistance pattern of C. difficile derived from hospitalized diarrheal patients, a systematic review and meta-analysis was performed.

Methods

Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline was followed to review published studies conducted. We searched bibliographic databases from PubMed, Scopus, Google Scholar, and Cochrane Library for studies on the prevalence and antimicrobial susceptibility testing on C. difficile. The weighted pooled prevalence and resistance for each antimicrobial agent was calculated using a random-effects model. A funnel plot and Egger’s regression test were used to see publication bias.

Results

A total of 15 studies were included. Ten articles for prevalence study and 5 additional studies for antimicrobial susceptibility testing of C. difficile were included. A total of 1967/7852 (25%) C. difficile were isolated from 10 included studies for prevalence study. The overall weighted pooled proportion (WPP) of C. difficile was 30% (95% CI: 10.0–49.0; p<0.001). The analysis showed substantial heterogeneity among studies (Cochran’s test = 7038.73, I2 = 99.87%; p<0.001). The weighed pooled antimicrobial resistance (WPR) were: vancomycin 3%(95% CI: 1.0–4.0, p<0.001); metronidazole 5%(95% CI: 3.0–7.0, p<0.001); clindamycin 61%(95% CI: 52.0–69.0, p<0.001); moxifloxacin 42%(95% CI: 29–54, p<0.001); tetracycline 35%(95% CI: 22–49, p<0.001); erythromycin 61%(95% CI: 48–75, p<0.001) and ciprofloxacin 64%(95% CI: 48–80; p< 0.001) using the random effect model.

Conclusions

A higher weighted pooled prevalence of C. difficile was observed. It needs a great deal of attention to decrease the prevailing prevalence. The resistance of C. difficile to metronidazole and vancomycin was low compared to other drugs used to treat C. difficile infection. Periodic antimicrobial resistance monitoring is vital for appropriate therapy of C. difficile infection.

Complete Genome Sequencing and Comparative Phenotypic Analysis Reveal the Discrepancy Between Clostridioides difficile ST81 and ST37 Isolates

Toxin A-negative, toxin B-positive Clostridioides difficile strains, which primarily include the ST81 and ST37 genotypes, are predominant in C. difficile infections leading to antibiotic-associated diarrhea in China. Recently, ST81 has been reported as the most prevalent genotype rather than ST37, although the genetic and functional characteristics of the two genotypes remain ambiguous. In this study, we conducted comprehensive comparative analysis of these two genotypes through complete genome sequencing and phenotypic profiling. The whole genome sequencing revealed that the ST81 and ST37 isolates were closely related genetically with similar gene compositions, and high rate of the core genome shared. The integrative and conjugative elements identified in ST81 were similar to those in ST37, albeit with more diverse and insertion regions. By characterizing the phenotypes related to colonization or survival in the host, we found that the ST81 isolates exhibited robust colonization ability and survival both in vitro and in vivo, enhanced spore production, and slightly increased motility, which may be attributable to the discrepancy in non-synonymous single-nucleotide polymorphisms in the relevant functional genes. Furthermore, the ST81 isolates displayed a significantly higher rate of resistance to fluoroquinolones compared with the ST37 isolates (94.12% vs. 62.5%) and mostly carried the amino acid substitution Asp426Val in GyrB. In summary, the results of our study indicate that ST81 isolates exhibit enhanced ability to transmit between hosts and survive in harsh environments, providing key genetic insights for further epidemiological investigations and surveillance of C. difficile infection.

Comparative Whole Genome Sequence Analysis and Biological Features of Clostridioides difficile Sequence Type 2‡

Clostridioides difficile sequence type 2 (ST2) has been increasingly recognized as one of the major genotypes in China, while the genomic characteristics and biological phenotypes of Chinese ST2 strains remain to be determined. We used whole-genome sequencing and phylogenetic analysis to investigate the genomic features of 182 ST2 strains, isolated between 2011 and 2017. PCR ribotyping (RT) was performed, and antibiotic resistance, toxin concentration, and sporulation capacity were measured. The core genome Maximum-likelihood phylogenetic analysis showed that ST2 strains were distinctly segregated into two genetically diverse lineages [L1 (67.0% from Northern America) and L2], while L2 further divided into two sub-lineages, SL2a and SL2b (73.5% from China). The 36 virulence-related genes were widely distributed in ST2 genomes, but in which only 11 antibiotic resistance-associated genes were dispersedly found. Among the 25 SL2b sequenced isolates, RT014 (40.0%, n = 10) and RT020 (28.0%, n = 7) were two main genotypes with no significant difference on antibiotic resistance (χ² = 0.024-2.667, P > 0.05). A non-synonymous amino acid substitution was found in tcdB (Y1975D) which was specific to SL2b. Although there was no significant difference in sporulation capacity between the two lineages, the average toxin B concentration (5.11 ± 3.20 ng/μL) in SL2b was significantly lower in comparison to those in L1 (10.49 ± 15.82 ng/μL) and SL2a (13.92 ± 2.39 ng/μL) (χ² = 12.30, P < 0.05). This study described the genomic characteristics of C. difficile ST2, with many virulence loci and few antibiotic resistance elements. The Chinese ST2 strains with the mutation in codon 1975 of the tcdB gene clustering in SL2b circulating in China express low toxin B, which may be associated with mild or moderate C. difficile infection.

The Intestinal Microbiota: Impacts of Antibiotics Therapy, Colonization Resistance, and Diseases

Trillions of microbes exist in the human body, particularly the gastrointestinal tract, coevolved with the host in a mutually beneficial relationship. The main role of the intestinal microbiome is the fermentation of non-digestible substrates and increased growth of beneficial microbes that produce key antimicrobial metabolites such as short-chain fatty acids, etc., to inhibit the growth of pathogenic microbes besides other functions. Intestinal microbiota can prevent pathogen colonization through the mechanism of colonization resistance. A wide range of resistomes are present in both beneficial and pathogenic microbes. Giving antibiotic exposure to the intestinal microbiome (both beneficial and hostile) can trigger a resistome response, affecting colonization resistance. The following review provides a mechanistic overview of the intestinal microbiome and the impacts of antibiotic therapy on pathogen colonization and diseases. Further, we also discuss the epidemiology of immunocompromised patients who are at high risk for nosocomial infections, colonization and decolonization of multi-drug resistant organisms in the intestine, and the direct and indirect mechanisms that govern colonization resistance to the pathogens.

Genomic evolution and virulence association of Clostridioides difficile sequence type 37 (ribotype 017) in China

Clostridioides difficile sequence type (ST) 37 (ribotype 017) is one of the most prevalent genotypes circulating in China. However, its genomic evolution and virulence determinants were rarely explored. Whole-genome sequencing, phylogeographic and phylogenetic analyses were conducted for C. difficile ST37 isolates. The 325 ST37 genomes from six continents, including North America (n = 66), South America (n = 4), Oceania (n = 7), Africa (n = 9), Europe (n = 138) and Asia (n = 101), were clustered into six major lineages, with region-dependent distributions, harbouring an array of antibiotic-resistance genes. The ST37 strains from China were divided into four distinct sublineages, showing five importation times and international sources. Isolates associated with severe infections exhibited significantly higher toxin productions, tcdB mRNA levels, and sporulation capacities (P < 0.001). Kyoto Encyclopedia of Genes and Genomes analysis showed 10 metabolic pathways were significantly enriched in the mutations among isolates associated with severe CDI (P < 0.05). Gene mutations in glycometabolism, amino acid metabolism and biosynthesis virtually causing instability in protein activity were correlated positively to the transcription of tcdR and negatively to the expression of toxin repressor genes, ccpA and codY. In summary, our study firstly presented genomic insights into genetic characteristics and virulence association of C. difficile ST37 in China. Gene mutations in certain important metabolic pathways are associated with severe symptoms and correlated with higher virulence in C. difficile ST37 isolates.

Prevalence and molecular subtyping of Blastocystis in patients with Clostridium difficile infection, Singapore

Background

Blastocystis is a common anaerobic colonic protist in humans with controversial pathogenicity. Clostridium difficile (C. difficile) is the commonest cause of infectious diarrhea in healthcare settings. The prevalence and subtype (ST) characteristics of Blastocystis in patients with C. difficile infection (CDI) are rarely documented. Therefore, the present study was conducted to investigate the prevalence and subtype characteristics of Blastocystis in patients with suspicion of CDI in Singapore.

Methods

Fecal samples were collected from 248 patients presenting with suspected CDI from a single tertiary hospital in Singapore. C. difficile was diagnosed through positive glutamate dehydrogenase (GDH) with or without toxin A/B using enzyme immunoassay methods. The prevalence and subtype genetic characteristics of Blastocystis were determined by polymerase chain reaction (PCR) amplification and analysis of the barcode region of the SSU rRNA gene.

Results

The proportion of C. difficile in patients with healthcare-associated diarrhea in this study was 44% (109/248). Among the 109 C. difficile-positive patients, 59 (54.1%, 59/109) tested positive for toxigenic C. difficile, which was considered CDI. Based on the sequence analyses of the barcode region of the SSU rRNA gene, 10.1% (25/248) of the patients were found to be Blastocystis-positive, and three subtypes were identified: ST7 (64%, 16/25), ST1 (20%, 5/25), and ST3 (16%, 4/25). Remarkably, we found five patients with Blastocystis and C. difficile coinfection, and further subtype analysis showed two with ST7, two with ST1, and one with ST3.

Conclusions

To the best of our knowledge, this is the first study to investigate the subtype distributions of Blastocystis in patients with CDI in Singapore. We found ST7 to be the predominant subtype in diarrheal patients. The pathogenicity of ST7 has been strongly suggested in previous in vitro and mouse model experiments, further confirming its potential pathogenicity to humans.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-021-04749-8.

Frequency of toxin genes and antibiotic resistance pattern of Clostridioides difficile isolates in diarrheal samples among hospitalized patients in Hamadan, Iran

AIM

This study was designed to investigate the prevalence of Clostridioides difficile, its toxin-producing genes, and antibiotic resistance patterns in diarrheal samples from hospitalized patients in Hamadan, Iran.

BACKGROUND

Today, concerns over Clostridioides difficile infection (CDI) have significantly increased due to reduced susceptibility to antibiotics used for CDI treatment. Toxins produced by C. difficile strains are associated with disease severity and outcome.

METHODS

In this cross-sectional study, a total of 130 diarrheal samples of patients admitted to different wards of three hospitals in Hamadan from November 2018 to September 2019 were collected. C. difficile isolates were identified by culture on CCFA and PCR (Polymerase chain reaction). The presence of toxin-encoding genes (tcdA and tcdB) and binary toxin genes (cdtA and cdtB) was analyzed by PCR. Resistance of the isolates to metronidazole, vancomycin and clindamycin antibiotics was determined using agar dilution method.

RESULTS

Out of 130 diarrheal samples from hospitalized patients, 16 (12.3%) C. difficile isolates were obtained. PCR results were positive for two toxin-producing genes, tcdA and tcdB, in all (100%) C. difficile isolates, and the binary toxin genes cdtA and cdtB were detected in 6 (37.5%) and 8 (50%) isolates, respectively. The results of antibiotic susceptibility testing showed resistance to metronidazole, vancomycin, and clindamycin in 3 (18.7%), 3 (18.7%), and 2 (12.5%) isolates, respectively, and all isolates were resistant to rifampicin.

CONCLUSION

The results of this study showed toxigenic C. difficile with tcdA ⁺ /tcdB ⁺ profile is a major cause of nosocomial diarrhea in Hamadan, and clinical laboratories should routinely perform C. difficile diagnostic testing on diarrheal specimens of hospitalized patients. Resistance to conventional antibiotic therapy against C. difficile should be considered as a warning to prevent irrational administration of antibiotics.

A 2-step algorithm combining glutamate dehydrogenase and nucleic acid amplification tests for the detection of Clostridioides difficile in stool specimens

The optimized diagnosis algorithm of Clostridioides difficile infection (CDI) is worldwide concerns. The purpose of this study was to assess the toxigenic C. difficile test performance and propose an optimal laboratory workflow for the diagnosis of CDI in mild virulent epidemic areas. Diarrhea samples collected from patients were analyzed by glutamate dehydrogenase (GDH), toxin AB (CDAB), and nucleic acid amplification test (NAAT). We assessed the performance of GDH, the GDH-CDAB algorithm, and the GDH-NAAT algorithm using toxigenic culture (TC) as a reference method. In this study, 186 diarrhea samples were collected. The numbers of TC-positive and TC-negative samples were 39 and 147, respectively. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and kappa of the GDH assay were 100%, 80.3%, 57.4%, 100%, and 0.63; of the GDH-CDAB algorithm were 48.7%, 97.3%, 82.6%, 87.7%, and 0.54; and of the GDH-NAAT algorithm were 74.4%, 100%, 100%, 93.6%, and 0.82, respectively. The GDH-NAAT algorithm has great concordance with TC in detecting toxigenic C. difficile (kappa = 0.82), while the sensitivity of the GDH-CDAB algorithm was too low to meet the demand of CDI diagnosis clinically. GDH-NAAT algorithm is recommended for the detection of toxigenic C. difficile with high specificity, increased sensitivity, and cost-effective.

Molecular characteristics of Clostridium difficile in children with acute gastroenteritis from Zhejiang

Background

Clostridium difficile infection (CDI) has an increasing pediatric prevalence worldwide. However, molecular characteristics of C. difficile in Chinese children with acute gastroenteritis have not been reported.

Methods

A five-year cross-sectional study was conducted in a tertiary children’s hospital in Zhejiang. Consecutive stool specimens from outpatient children with acute gastroenteritis were cultured for C. difficile, and isolates then were analyzed for toxin genes, multi-locus sequence type and antimicrobial resistance. Diarrhea-related viruses were detected, and demographic data were collected.

Results

A total of 115 CDI cases (14.3%), and 69 co-infected cases with both viruses and toxigenic C. difficile, were found in the 804 stool samples. The 186 C. difficile isolates included 6 of toxin A-positive/toxin B-positive/binary toxin-positive (A⁺B⁺CDT⁺), 139 of A⁺B⁺CDT⁻, 3 of A⁻B⁺CDT⁺, 36 of A⁻B⁺CDT⁻ and 2 of A⁻B⁻CDT⁻. Sequence types 26 (17.7%), 35 (11.3%), 39 (12.4%), 54 (16.7%), and 152 (11.3%) were major genotypes with significant differences among different antimicrobial resistances (Fisher's exact test, P < 0.001). The A⁻B⁺ isolates had significantly higher resistance, compared to erythromycin, rifampin, moxifloxacin, and gatifloxacin, than that of the A⁺B⁺ (χ² = 7.78 to 29.26, P < 0.01). The positive CDI rate in infants (16.2%) was significantly higher than that of children over 1 year old (10.8%) (χ² = 4.39, P = 0.036).

Conclusions

CDI has been revealed as a major cause of acute gastroenteritis in children with various genotypes. The role of toxigenic C. difficile and risk factors of CDI should be emphatically considered in subsequent diarrhea surveillance in children from China.

Comparative Study of Clostridium difficile Clinical Detection Methods in Patients with Diarrhoea

Objectives

The aim of this study was to evaluate the clinical application of three methods for detecting Clostridium difficile in fecal samples.

Methods

One hundred and fifty fecal specimens were collected and tested for C. difficile using three methods: (1) the toxigenic culture (TC); (2) the VIDAS enzyme immunoassay (EIA): the VIDAS glutamate dehydrogenase (GDH) assay and toxin A/B assay were used to detect GDH antigen and A/B toxin; and (3) the GeneXpert PCR assay. The toxigenic culture was used as a reference to evaluate the performance of the VIDAS EIA and the GeneXpert PCR assay.

Results

Of 150 specimens, 26 carried both A and B toxin genes, and none of the samples were positive for the binary toxin gene. Toxin-producing C. difficile using three methods: (1) the toxigenic culture (TC); (2) the VIDAS enzyme immunoassay (EIA): the VIDAS glutamate dehydrogenase (GDH) assay and toxin A/B assay were used to detect GDH antigen and A/B toxin; and (3) the GeneXpert PCR assay. The toxigenic culture was used as a reference to evaluate the performance of the VIDAS EIA and the GeneXpert PCR assay. C. difficile using three methods: (1) the toxigenic culture (TC); (2) the VIDAS enzyme immunoassay (EIA): the VIDAS glutamate dehydrogenase (GDH) assay and toxin A/B assay were used to detect GDH antigen and A/B toxin; and (3) the GeneXpert PCR assay. The toxigenic culture was used as a reference to evaluate the performance of the VIDAS EIA and the GeneXpert PCR assay.

Conclusion

The VIDAS GDH assay is useful for initial screening of C. difficile using three methods: (1) the toxigenic culture (TC); (2) the VIDAS enzyme immunoassay (EIA): the VIDAS glutamate dehydrogenase (GDH) assay and toxin A/B assay were used to detect GDH antigen and A/B toxin; and (3) the GeneXpert PCR assay. The toxigenic culture was used as a reference to evaluate the performance of the VIDAS EIA and the GeneXpert PCR assay.

High-Level Resistance of Toxigenic Clostridioides difficile Genotype to Macrolide-Lincosamide- Streptogramin B in Community Acquired Patients in Eastern China

Background

Clostridioides difficile resistant to macrolide-lincosamide-streptogramin B (MLS_B) has not been reported in China.

Methods

In a cross-sectional study in two tertiary hospitals, C. difficile isolates from stool specimens from community-onset, hospital-associated diarrheal patients were analyzed for toxin genes, genotype, and antibiotic resistance, and the patients’ clinical charts were reviewed.

Results

A total of 190 (15.2%) isolates (102 A⁺B⁺ and 88 A⁻B⁺) from 1250 community acquired (CA) patients were recovered and all were susceptible to vancomycin and metronidazole. High-level resistance (minimum inhibitory concentration > 128 mg/L) to erythromycin and clindamycin was recorded in 77.9% and 88.4% of the tested isolates, respectively. Furthermore, 89.3% (159/178) of the isolates resistant to MLS_B carried the erythromycin resistance methylase gene (ermB). The statistically significant factors associated with C. difficile infection (CDI) induced by A⁻B⁺ isolates with MLS_B resistance included a severity score of >2 (odds ratio [95% confidence interval], 7.43 [2.31–23.87]) and platelet count (cells × 10⁹ cells/L) < 100 [5.19 (1.58–17.04)]. The proportion of A⁻B⁺ increased with enhanced CDI severity (x² = 21.62, P < 0.001), which was significantly higher than that of ermB-positive A⁺B⁺ in severity score of 4 (x² = 8.61, P = 0.003). The average severity score of ermB-positive isolates was significantly higher than that of ermB-negative isolates in A⁻B⁺ (Z = −2.41, P = 0.016).

Conclusion

The ermB-positive A⁻B⁺C. difficile with MLS_B resistance is described for the first time as a potential epidemic clone inducing severe CDI in CA diarrheal patients in Eastern China.

Different molecular characteristics and antimicrobial resistance profiles of Clostridium difficile in the Asia-Pacific region

Molecular epidemiology of Clostridium difficile infection (CDI) has been extensively studied in North America and Europe; however, limited data on CDI are available in the Asia-Pacific region. A multicentre retrospective study was conducted in this region. C. difficile isolates were subjected to multilocus sequence typing (ST) and antimicrobial susceptibility testing. Totally, 394 isolates were collected from Hangzhou, Hong Kong, China; Busan, South Korea; Fukuoka, Japan; Singapore; Perth, Sydney, Australia; New York, the United States. C. difficile isolates included 337 toxin A-positive/B-positive/binary toxin-negative (A⁺B⁺CDT^-), 48 A^-B⁺CDT^-, and nine A⁺B⁺CDT⁺. Distribution of dominant STs varied geographically with ST17 in Fukuoka (18.6%), Busan (56.0%), ST2 in Sydney (20.4%), Perth (25.8%). The antimicrobial resistance patterns were significantly different among the eight sites (χ² = 325.64, p < 0.001). Five major clonal complexes correlated with unique antimicrobial resistances. Healthcare-associated (HA) CDI was mainly from older patients with more frequent antimicrobial use and higher A^-B⁺ positive rates. Higher resistance to gatifloxacin, tetracycline, and erythromycin were observed in HA-CDI patients (χ² = 4.76-7.89, p = 0.005-0.029). In conclusion, multiple C. difficile genotypes with varied antimicrobial resistance patterns have been circulating in the Asia-Pacific region. A^-B⁺ isolates from older patients with prior antimicrobial use were correlated with HA-CDI.

Molecular Epidemiology and Risk Factors of Clostridium difficile ST81 Infection in a Teaching Hospital in Eastern China

BACKGROUND

The prevalence of Clostridium difficile causes an increased morbidity and mortality of inpatients, especially in Europe and North America, while data on C. difficile infection (CDI) are limited in China.

METHODS

From September 2014 to August 2019, 562 C. difficile isolates were collected from patients and screened for toxin genes. Multilocus sequence typing (MLST) and antimicrobial susceptibility tests by E-test and agar dilution method were performed. A case group composed of patients infected with sequence type (ST) 81 C. difficile was compared to the non-ST81 infection group and non CDI diarrhea patients for risk factor and outcome analyses.

RESULTS

The incidence of inpatients with CDI was 7.06 cases per 10,000 patient-days. Of the 562 C. difficile isolates, ST81(22.78%) was the predominant clone over this period, followed by ST54 (11.21%), ST3 (9.61%), and ST2 (8.72%). Toxin genotype tcdA+tcdB+cdt- accounted for 50.18% of all strains, while 29.54% were tcdA-tcdB+cdt- genotypes. Overall, no isolate was resistant to vancomycin, teicoplanin or daptomycin, and resistance rates to meropenem gradually decreased during these years. Although several metronidazole-resistant strains were isolated in this study, the MIC values decreased during this period. Resistance rates to moxifloxacin and clindamycin remained higher than those to the other antibiotics. Among CDI inpatients, longer hospitalization, usage of prednisolone, suffering from chronic kidney disease or connective tissue diseases and admission to emergency ward 2 or emergency ICU were significant risk factors for ST81 clone infection. All-cause mortality of these CDI patients was 4.92%(n=18), while the recurrent cases accounted for 5.74%(n=21). The 60-day mortality of ST81-CDI was significantly higher than non-ST81 infected group, while ST81 also accounted for most of the recurrent CDI cases.

CONCLUSION

This study revealed the molecular epidemiology and risk factors for the dominant C. difficile ST81 genotype infection in eastern China. Continuous and stringent surveillance on the emerging ST81 genotype needs to be initiated.

Burden of Clostridium (Clostridioides) difficile Infection among Patients in Western Asia: A Systematic Review and Meta-Analysis

BACKGROUND

Clostridium difficile is the most common causes of hospital-acquired diarrhea affecting particularly hospitalized patients globally. This organism has re-emerged in recent years with significant morbidity and mortality. The present study aimed to estimate the burden of C. difficile infection (CDI) and to acquire information on the overall rates of community- and hospital-acquired CDI in western Asia.

METHODS

A systematic literature search was performed to identify articles published from the eight Persian Gulf countries in western Asia including Iran, Iraq, Bahrain, Kuwait, Oman, Qatar, Saudi Arabia, and the United Arab Emirates in the electronic databases within Jan of 2000 to Dec of 2017. Then, 20 publications which met our inclusion criteria were selected for data extraction and analysis by Comprehensive Meta-Analysis Software.

RESULTS

Twenty studies reported the prevalence of toxigenic strains of C. difficile among patients from Persian Gulf countries, of these the pooled prevalence of CDI was 9% (95% CI: 6.5%-12.5%). Totally, 8 studies showed the prevalence of hospital-acquired CDI, from those studies the prevalence of CDI was estimated 8.4% (95% CI: 4.9%-14.1%). Moreover, 7 studies reported the prevalence of community-acquired CDI, from those studies the prevalence of CDI was estimated 1.8% (95% CI: 1.2%-2.9%).

CONCLUSION

The prevalence of CDI in western Asia is lower than southern and eastern region. Moreover, the lower prevalence of community-acquired CDI compared to hospital-acquired CDI, indicate that the source of infection in western Asia is more likely in the hospitals.

Adaptation of host transmission cycle during Clostridium difficile speciation

Bacterial speciation is a fundamental evolutionary process characterized by diverging genotypic and phenotypic properties. However, the selective forces that affect genetic adaptations and how they relate to the biological changes that underpin the formation of a new bacterial species remain poorly understood. Here, we show that the spore-forming, healthcare-associated enteropathogen Clostridium difficile is actively undergoing speciation. Through large-scale genomic analysis of 906 strains, we demonstrate that the ongoing speciation process is linked to positive selection on core genes in the newly forming species that are involved in sporulation and the metabolism of simple dietary sugars. Functional validation shows that the new C. difficile produces spores that are more resistant and have increased sporulation and host colonization capacity when glucose or fructose is available for metabolism. Thus, we report the formation of an emerging C. difficile species, selected for metabolizing simple dietary sugars and producing high levels of resistant spores, that is adapted for healthcare-mediated transmission.

The prevalence of antibiotic-resistant Clostridium species in Iran: a meta-analysis

Clostridium species are ubiquitous and associated with various diseases in animals and humans. However, there is little knowledge about the prevalence of their resistance to antibiotics in Iran. Therefore, the aim of this study was to determine the prevalence of antibiotic-resistant Clostridium species in Iran through a meta-analysis of eligible studies published up until December 2018. Fourteen articles on the drug resistance of Clostridium species in Iran were included in the current study following a search in PubMed, Scopus and Google Scholar databases using relevant keywords and screening based on inclusion and exclusion criteria. Antibiotic resistance rates of C. difficile to ampicillin (42.8%), ciprofloxacin (69.5%), clindamycin (84.3%), erythromycin (61.5%), gentamicin (93.5%), nalidixic acid (92.9%), tetracycline (32.5%), imipenem (39.6%), levofloxacin (93.4%), ertapenem (58.7%), piperacillin/tazobactam (56.5%), kanamycin (100%), colistin (100%), ceftazidime (76%), amikacin (76.5%), moxifloxacin (67.9%) and cefotaxime (95%) were high. In addition, resistance of C. perfringens to ampicillin (25.8%), erythromycin (32.9%), gentamicin (45.4%), nalidixic acid (52.5%), tetracycline (19.5%), penicillin (21.8%), trimethoprim-sulfamethoxazole (32.1%), amoxicillin (19.3%), imipenem (38%), cloxacillin (100%), oxacillin (45.6%), bacitracin (89.1%) and colistin (40%) was high. Metronidazole and vancomycin, as the first-line therapies, fidaxomicin, tetracyclines (except tetracycline), rifampicin and chloramphenicol can still be used for the treatment of C. difficile infections. However, the present results do not recommend the use of penicillin, bacitracin and tetracycline for the treatment of C. perfringens infections in humans and domestic animals in Iran.

Independent Microevolution Mediated by Mobile Genetic Elements of Individual Clostridium difficile Isolates from Clade 4 Revealed by Whole-Genome Sequencing

Mobile genetic elements play a key role in the continuing evolution of Clostridium difficile, resulting in the emergence of new phenotypes for individual isolates. On the basis of whole-genome sequencing analysis, we comprehensively explored transposons, CRISPR, prophage, and genetic sites for drug resistance within clade 4 C. difficile isolates with different sequence types. Great diversity in MGEs and a high rate of multidrug resistance were found within this clade, including new transposons, Tn4453a/b with aac(6′) aph(2′′) instead of catD, and a relatively high rate of prophage-carried CRISPR arrays. These findings provide important new insights into the mechanism of genome remodeling within clade 4 and offer a new method for typing and tracing the origins of closely related isolates.

Horizontal gene transfer of mobile genetic elements (MGEs) accounts for the mosaic genome of Clostridium difficile, leading to acquisition of new phenotypes, including drug resistance and reconstruction of the genomes. MGEs were analyzed according to the whole-genome sequences of 37 C. difficile isolates with a variety of sequence types (STs) within clade 4 from China. Great diversity was found in each transposon even within isolates with the same ST. Two novel transposons were identified in isolates ZR9 and ZR18, of which approximately one third to half of the genes showed heterogenous origins compared with the usual intestinal bacterial genes. Most importantly, catD, known to be harbored by Tn4453a/b, was replaced by aac(6′) aph(2′′) in isolates 2, 7, and 28. This phenomenon illustrated the frequent occurrence of gene exchanges between C. difficile and other enterobacteria with individual heterogeneity. Numerous prophages and CRISPR arrays were identified in C. difficile isolates of clade 4. Approximately 20% of spacers were located in prophage-carried CRISPR arrays, providing a new method for typing and tracing the origins of closely related isolates, as well as in-depth studies of the mechanism underlying genome remodeling. The rates of drug resistance were obviously higher than those reported previously around the world, although all isolates retained high sensitivity to vancomycin and metronidazole. The increasing number of C. difficile isolates resistant to all antibiotics tested here suggests the ease with which resistance is acquired in vivo. This study gives insights into the genetic mechanism of microevolution within clade 4.

IMPORTANCE Mobile genetic elements play a key role in the continuing evolution of Clostridium difficile, resulting in the emergence of new phenotypes for individual isolates. On the basis of whole-genome sequencing analysis, we comprehensively explored transposons, CRISPR, prophage, and genetic sites for drug resistance within clade 4 C. difficile isolates with different sequence types. Great diversity in MGEs and a high rate of multidrug resistance were found within this clade, including new transposons, Tn4453a/b with aac(6′) aph(2′′) instead of catD, and a relatively high rate of prophage-carried CRISPR arrays. These findings provide important new insights into the mechanism of genome remodeling within clade 4 and offer a new method for typing and tracing the origins of closely related isolates.

Epidemiology of Clostridium difficile infection in hospitalized adults and the first isolation of C. difficile PCR ribotype 027 in central China

Background

Clostridium difficile infection (CDI) is an emerging healthcare problem in the world. The purpose of this study was to perform a systematic epidemiological research of CDI in Tongji hospital, the central of China.

Methods

Stool samples from hospitalized adults suspected of CDI were enrolled. The diagnosis of CDI were based on the combination of clinical symptoms and laboratory results. Clinical features of CDI and non-CDI patients were compared by appropriate statistical tests to determine the risk factors of CDI. Multilocus sequence typing (MLST) was employed for molecular epidemiological analysis. Susceptibility testing and relevant antimicrobial agent resistance genes were performed as well.

Results

From June 2016 to September 2017, 839 hospitalized adults were enrolled. Among them, 107 (12.8%, 107/839) patients were C. difficile culture positive, and 73 (8.7%, 73/839) were infected with toxigenic C. difficile (TCD), with tcdA + tcdB+ strains accounting for 90.4% (66/73) and tcdA-tcdB+ for 9.6% (7/73). Meanwhile, two TCD strains were binary toxin positive and one of them was finally identified as CD027. Severe symptoms were observed in these two cases. Multivariate analysis indicated antibiotic exposure (p = 0.001, OR = 5.035) and kidney disease (p = 0.015, OR = 8.329) significantly increased the risk of CDI. Phylogenetic tree analysis demonstrated 21 different STs, including one new ST (ST467); and the most dominant type was ST54 (35.6%, 26/73). Multidrug-resistant (MDR) TCD were 53.4% (39/73); resistance to ciprofloxacin, erythromycin, and clindamycin were > 50%. Other antibiotics showed relative efficiency and all strains were susceptible to metronidazole and vancomycin. All moxifloxacin-resistant isolates carried a mutation in GyrA (Thr82 → Ile), with one both having mutation in GyrB (Ser366 → Ala).

Conclusions

Knowledge of epidemiological information for CDI is limited in China. Our finding indicated tcdA + tcdB+ C. difficile strains were the dominant for CDI in our hospital. Significant risk factors for CDI in our setting appeared to be antibiotic exposure and kidney disease. Metronidazole and vancomycin were still effective for CDI. Although no outbreak was observed, the first isolation of CD027 in center China implied the potential spread of this hypervirulent clone. Further studies are needed to enhance our understanding of the epidemiology of CDI in China.

Electronic supplementary material

The online version of this article (10.1186/s12879-019-3841-6) contains supplementary material, which is available to authorized users.

The first isolation of Clostridium difficile RT078/ST11 from pigs in China

We investigated the molecular characteristics and antimicrobial susceptibility of Clostridium difficile isolated from animals in China. We obtained 538 rectal swabs from pigs, chickens and ducks in 5 provinces during 2015 and 2016. C. difficile isolates were characterized by detection of toxin genes, multilocus sequence typing and ribotyping. And antimicrobial susceptibility testing was performed using the agar dilution method. Out of 538 samples, 44 (8.2%) were C. difficile positive with high prevalence in pigs (n = 31). Among these, 39 (88.6%) were toxigenic including 14 (31.8%) that were A+B+CDT+ and 13 (29.5%) A+B+. The remaining 12 (27.3%) were A-B+. We identified 7 ST types and 6 PCR ribotypes. The most predominant type was ST11/RT078 with toxin profile A+B+CDT+ and all were isolated from piglets with diarrhea. ST109 isolates possessed two different toxigenic profiles (A-B-CDT- and A-B+CDT-) and although it was not the most prevalent sequence type, but it was widely distributed between chickens, ducks and pigs in the 5 provinces. All C. difficile isolates were fully susceptible to vancomycin, metronidazole, fidaxomicin, amoxicillin/clavulanate and meropenem but retained resistance to 4 or 5 of the remaining antibiotics, especially cefotaxime, tetracycline, ciprofloxacin, cefoxitin. The RT078/ST11 isolates were simultaneously resistant to cefotaxime, tetracycline, cefoxitin, ciprofloxacin and imipenem. This is the first report of the molecular epidemiology of C. difficile isolated from food animals in China. We identified the epidemic strain RT078/ST11 as the predominate isolate among the animals we screened in our study.

Bacteroides fragilis Prevents Clostridium difficile Infection in a Mouse Model by Restoring Gut Barrier and Microbiome Regulation

Clostridium difficile is currently the leading cause of nosocomial infection. Antibiotics remain the first-line therapy for C. difficile-associated diseases (CDAD), despite the risks of resistance promotion and further gut microbiota perturbation. Notably, the abundance of Bacteroides fragilis was reported to be significantly decreased in CDAD patients. This study aimed to clarify the prophylactic effects of B. fragilis strain ZY-312 in a mouse model of C. difficile infection (CDI). The CDI mouse model was successfully created using C. difficile strain VPI 10463 spores, as confirmed by lethal diarrhea (12.5% survival rate), serious gut barrier disruption, and microbiota disruption. CDI model mice prophylactically treated with B. fragilis exhibited significantly higher survival rates (100% in low dosage group, 87.5% in high dosage group) and improved clinical manifestations. Histopathological analysis of colon and cecum tissue samples revealed an intact gut barrier with strong ZO-1 and Muc-2 expression. The bacterial diversity and relative abundance of gut microbiota were significantly improved. Interestingly, the relative abundance of Akkermansia muciniphila was positively correlated with B. fragilis treatment. In vitro experiments showed that B. fragilis inhibited C. difficile adherence, and attenuated the decrease in CDI-induced transepithelial electrical resistance, ZO-1 and MUC-2 loss, and apoptosis, suggesting that B. fragilis protected against CDI possibly by resisting pathogen colonization and improving gut barrier integrity and functions. In summary, B. fragilis exerted protective effects on a CDI mouse model by modulating gut microbiota and alleviating barrier destruction, thereby relieving epithelial stress and pathogenic colitis triggered by C. difficile. This study provides an alternative preventative measure for CDI and lays the foundations for further investigations of the relationships among opportunistic pathogens, commensal microbiota, and the gut barrier.

Co-infection of Clostridioides (Clostridium) difficile GMU1 and Bacillus cereus GMU2 in one patient in Guizhou, China

Clostridioides (Clostridium) difficile and Bacillus cereus infections are frequently reported in human individually. However, co-infection of both pathogens in human is extremely rare. In the present study, we reported a case of human enteric disease caused by co-infection of C. difficile and B. cereus in Guizhou, China. The 16S rDNA sequencing result showed that C. difficile GMU1 and B. cereus GMU2 were most related to C. difficile ATCC 9689 and B. cereus ATCC 14579. The toxin genotype of C. difficile GMU1 and B. cereus GMU2 were tcdA⁺tcdB⁺tcdC⁺ and bceT⁺nheA⁺nheB⁺nheC⁺, respectively. Cytotoxicity assay demonstrated that C. difficile GMU1 produced significantly higher toxin B compare to C. difficile 630 stain. In contrast, B. cereus GMU2 has comparable NheA toxin productivity compare to previous report. The antimicrobial susceptibility test showed that the combination of ampicillin and vancomycin was most efficient to inhibit both C. difficile GMU1 and B. cereus GMU2.

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.

Molecular Characterization of Clostridium difficile Isolates in China From 2010 to 2015

Clostridium difficile infection (CDI) has become a worldwide public health problem causing high mortality and a large disease burden. Molecular typing and analysis is important for surveillance and infection control of CDI. However, molecular characterization of C. difficile across China is extremely rare. Here, we report on the toxin profiles, molecular subtyping with multilocus sequence typing (MLST) and PCR ribotyping, and epidemiological characteristics of 199 C. difficile isolates collected between 2010 through 2015 from 13 participating centers across China. We identified 35 STs and 27 ribotypes (RTs) among the 199 C. difficile isolates: ST35 (15.58%), ST3 (15.08%), ST37 (12.06%), and RT017 (14.07%), RT001 (12.06%), RT012 (11.56%) are the most prevalent. One isolate with ST1 and 8 isolates with ST 11 were identified. We identified a new ST in this study, denoted ST332. The toxin profile tcdA⁺tcdB⁺tcdC⁺tcdR⁺tcdE⁺CDT^- (65.83%) was the predominant profile. Furthermore, 11 isolates with positive binary toxin genes were discovered. According to the PCR ribotyping, one isolate with RT 027, and 6 isolates with RT 078 were confirmed. The epidemiological characteristics of C. difficile in China shows geographical differences, and both the toxin profile and molecular types exhibit great diversity across the different areas.

Use of matrix-assisted laser desorption ionization-time of flight mass spectrometry to identify MLST clade 4 Clostridium difficile isolates

Clostridium difficile is the leading cause of health care-associated infections. Previous studies suggest that C. difficile MLST clade 4 strains with higher drug resistance rates constitute the major clone spreading in China. Thus development of a rapid and accurate typing method for these strains is needed to monitor the epidemiology of this clone and to guide clinical treatment. A total of 160 non-duplicate C. difficile isolates recovered from three large teaching hospitals in Beijing were studied. All the 41 clade 4 C. difficile isolates clustered together on the PCA dendrogram. Spectra peak statistics revealed that five markers (2691.43Da, 2704.91Da, 2711.93Da, 3247.27Da and 3290.76Da) can easily and reliably distinguish between clade 4 and non-clade 4 isolates, with area under the curve (AUC) values of 0.991, 0.997, 0.973, 1 and 1, respectively. In conclusion, MALDI-TOF MS is a very simple and accurate method for identifying C. difficile MLST clade 4 strains.

A retrospective study of community-acquired Clostridium difficile infection in southwest China

To identify the prevalence and characteristics of community-acquired Clostridium difficile infection (CA-CDI) in southwest China, we conducted a cross-sectional study. 978 diarrhea patients were enrolled and stool specimens’ DNA was screened for virulence genes. Bacterial culture was performed and isolates were characterized by PCR ribotyping and multilocus sequence typing. Toxin genes tcdA and/or tcdB were found in 138/978 (14.11%) cases for fecal samples. A total of 55 C. difficile strains were isolated (5.62%). The positive rate of toxin genes and isolation results had no statistical significance between children and adults groups. However, some clinical features, such as fecal property, diarrhea times before hospital treatment shown difference between two groups. The watery stool was more likely found in children, while the blood stool for adults; most of children cases diarrhea ≤3 times before hospital treatment, and adults diarrhea >3 times. Independent risk factor associated with CA-CDI was patients with fever. ST35/RT046 (18.18%), ST54/RT012 (14.55%), ST3/RT001 (14.55%) and ST3/RT009 (12.73%) were the most distributed genotype profiles. ST35/RT046, ST3/RT001 and ST3/RT009 were the commonly found in children patients but ST54/RT012 for adults. The prevalence of CA-CDI in Yunnan province was relatively high, and isolates displayed heterogeneity between children and adults groups.

Epidemiology and risk factors for Clostridium difficile-associated diarrhea in adult inpatients in a university hospital in China

BACKGROUND

Clostridium difficile-associated diarrhea (CDAD) is an important disease with rising incidence and mortality in western countries. However, studies about CDAD in China are limited. The aims of this study are to investigate the epidemiology and risk factors of CDAD in a university hospital located in Eastern China.

METHODS

Diarrhea samples of all adult inpatients were collected for C difficile culture prospectively from August 2013-April 2014. Suspected colonies were identified by biochemical identification cards. Confirmed C difficile isolates were further analyzed for the presence of toxin genes and typed by polymerase chain reaction ribotyping. Patient demographics, presumed risk factors, clinical manifestations, and laboratory findings were collected through inpatient medical record systems retrospectively.

RESULTS

In total, 45 stains of toxigenic C difficile were isolated from 315 nonrepetitive diarrhea samples. The isolation rate was 14.29% (45/315). No RT027/ST1 strain was found. An outbreak of CDAD occurred in the digestive ward and was finally found to be caused by ST35 strains during this study. Coloclysis and diabetes were found to be independent risk factors of CDAD, besides the common risk factors previously reported.

CONCLUSIONS

CDAD is not uncommon in Chinese hospitals. C difficile ST35 as a new strain causing outbreaks should be noticed. Coloclysis and diabetes are new independent risk factors for CDAD, and further study is needed.

Molecular epidemiology of fluoroquinolone resistant Salmonella in Africa: A systematic review and meta-analysis

BACKGROUND

Wide-ranging evidence on the occurrence of fluoroquinolone (FQ) resistance genetic determinants in African Salmonella strains is not available. The main objectives of this study were to assess the heterogeneity, estimate pooled proportions and describe the preponderance of FQ-resistance determinants in typhoidal and non-typhoidal Salmonella (NTS) isolates of Africa.

METHODS

Genetic and phenotypic data on 6103 Salmonella isolates were considered. Meta- and frequency analyses were performed depending on the number of studies by category, number of isolates and risks of bias. A random effects model was used to assess heterogeneity and estimate pooled proportions. Relative and cumulative frequencies were calculated to describe the overall preponderance of FQ-resistance determinants in quinolone resistant isolates.

RESULTS

The pooled proportion of gyrA mutants (Salmonella enterica serovar Typhi, Salmonella enterica serovar Typhimurium, and Salmonella enterica serovar Enteritidis) was estimated at 5.7% (95% Confidence interval (CI) = 2.6, 9.8; Tau squared (T2) = 0.1105), and was higher in S. Typhi than in S. Typhimurium (odds ratio (OR) = 3.3, 95%CI = 2, 5.7). The proportions of each of gyrB and parC mutants, and strains with Plasmid Mediated Quinolone Resistance genes (qnrA, qnrB and qnrS) were low (≤ 0.3%). Overall, 23 mutant serotypes were identified, and most strains had mutations at codons encoding Ser83 and Asp87 of gyrA (82%, 95%CI = 78, 86).

CONCLUSIONS

Mutations at gyrA appear to account for ciprofloxacin non-susceptibility in most clinical Salmonella strains in Africa. The estimates could be harnessed to develop a mismatch-amplification mutation-assay for the detection of FQ-resistant strains in Africa.

Molecular epidemiology and antimicrobial susceptibility of Clostridium difficile isolated from hospitals during a 4-year period in China

OBJECTIVE

The aim of this study was to perform molecular characterization for and determine the antimicrobial susceptibility profiles of Clostridium difficile collected from hospitals during a 4-year period (2009-2013) in China.

METHODS

Strains of toxigenic C. difficile were isolated from patients with diarrhoea, and this was followed by typing using multilocus sequence typing (MLST) and testing for susceptibility to 10 antimicrobials by using the E-test. The mechanisms of resistance to moxifloxacin, erythromycin, clindamycin and tetracycline were investigated by PCR.

RESULTS

A total of 405 non-duplicate toxigenic C. difficile isolates were identified, while 31 sequence types (STs) were identified. A predominant type, ST-54, accounted for 20.2 % of the STs, followed by ST-35 (16.3 %) and ST-37 (13.6 %). We found that 6.2 % of the isolates were binary toxin genes-positive, and 83.7 % of these belonged to ST-5. All of the isolates demonstrated 100 % susceptibility to first-line Clostridium difficile infection (CDI) therapies (i.e. metronidazole and vancomycin), while the resistance rates varied for the other antibiotics tested. Two hundred and ninety three (72.3 %) isolates were susceptible to moxifloxacin. All 112 moxifloxacin-resistant isolates had mutations resulting in an amino acid substitution in gryA and/or gyrB. The ermB gene was detected in 86.7 % (241/278) of the erythromycin- and clindamycin-resistant isolates, while the tetM gene was present in 97.1 % (85/87) of the tetracycline-resistant isolates.

CONCLUSION

MLST typing revealed a wide variety of STs causing CDI, while ST-54 was the most common ST. All of the isolates were susceptible to metronidazole and vancomycin, while the resistance rates varied for the other antibiotics tested. There were no changes in the trends for the STs and antibiotic susceptibility profiles over 4 years.

Hospital-acquired Clostridium difficile infection in Mainland China: A seven-year (2009-2016) retrospective study in a large university hospital

Clostridium difficile infection (CDI) is associated with risk for severe disease and high mortality. Little is known about the extent of hospital-acquired CDI in Mainland China. In this study, we aimed to investigate the annual CDI incidence, bacterial genotypes, risk factors for severe CDI and survival over a 7-year period. A total of 307 hospital-acquired CDI patients were enrolled, and 70.7% of these cases were male. CDI incidence was 3.4 per 10,000 admissions. Thirty-three different sequence types (STs) were identified, among which ST-54 (18.2%), ST-35 (16.6%) and ST-37 (12.1%) were the most prevalent. During the follow-up period, 66 (21.5%) patients developed severe CDI and 32 (10.4%) patients died in 30 days. Multivariate analysis revealed that bloodstream infection, pulmonary infection and C-reactive protein were significantly associated with severe CDI. After adjustment for potential confounders, old age, bloodstream infection, fever, mechanical ventilation, connective tissue disease, macrolide use and hypoalbuminaemia were independently associated with 30-day mortality in patients with CDI. The CDI prevalence has been low and stable in our center, and STs of Clostridium difficile were different from dominant STs in Western countries. Our data emphasize the need of continued education and surveillance of CDI to reduce the CDI burden in China.

Nosocomial transmission of Clostridium difficile Genotype ST81 in a General Teaching Hospital in China traced by whole genome sequencing

Clostridium difficile infection (CDI) is increasingly recognized globally as a cause of significant morbidity and mortality. This study aimed to provide insight into the various dynamics of C. difficile transmission and infection in the hospital. We monitored the toxin and resistance profiles as well as evolutionary relationships of C. difficile strains to determine the epidemiology over time in a teaching hospital in Shanghai, China between May 2014 and August 2015. The CDI incidence of inpatients and outpatients were 67.7 cases and 0.3 cases per 100,000 patient-days, with a nosocomial patient-environment-patient transmission in May and June 2015. C. difficile genotype ST81, a clone with tcdA-negative and tcdB-positive, was not only the most common strain (30.8%, 28/91) but also had much higher resistance rates to clindamycin and moxifloxacin compared with non-ST81 genotypes. Hospitalized patients infected with ST81 genotypes were over 65 years of age and had more comorbidities, however patients infected with ST81 presented with less clinical symptoms than non-ST81 infected patients. This study provides initial epidemiological evidence that C. difficile ST81 is a successful epidemic genotype that deserves continuous surveillance in China.

Antimicrobial susceptibility of Clostridium difficile isolates from ICU colonized patients revealed alert to ST-37 (RT 017) isolates

Seventy Clostridium difficile isolates from ICU colonized patients were tested for antimicrobial susceptibility and screened for resistance determinants. We found that multilocus sequence type 37 (ribotype 017) toxin A-negative/B-positive isolates were more likely resistant to moxifloxacin than toxin A-positive/B-positive isolates (41.7% versus 9.3%) with major variations in both GyrA (Thr82Ile) and GyrB (Ser366Ala), suggesting that the use of quinolone should be more strictly regulated.