Multilocus sequence typing (MLST) analysis of 104 Clostridium difficile strains isolated from China

Different bile acids have versatile effects on sporulation, toxin levels and biofilm formation of different Clostridioides difficile strains

Clostridioides difficile infection develops following ingestion of virulent stains by a susceptible host. Once germinated, toxins TcdA and TcdB, and in some of the strains binary toxin, are secreted, eliciting disease. Bile acids play a significant role in the process of spore germination and outgrowth, with cholate and its derivative enhancing colony formation, while chenodeoxycholate inhibit germination and outgrowth. This work investigated bile acids' impact on spore germination, toxin levels and biofilm formation in various strain types (STs). Thirty C. difficile isolates (A⁺ B⁺ CDT^-\+) of different STs were exposed to increasing concentrations of the bile acids, cholic acid (CA), taurocholic acid (TCA) and chenodeoxycholic acid (CDCA). Following treatments, spore germination was determined. Toxin concentrations were semi-quantified using the C. Diff Tox A/B II™ kit. Biofilm formation was detected by the microplate assay with crystal violet. SYTO® 9 and propidium iodide staining were used for live and dead cell detection, respectively, inside the biofilm. Toxins levels were increased by 1.5-28-fold in response to CA and by 1.5-20-fold in response to TCA, and decreased by 1-37-fold due to CDCA exposure. CA had a concentration-dependent effect on biofilm formation, with the low concentration (0.1%) inducing- and the higher concentrations inhibiting biofilm formation, while CDCA significantly reduced biofilm production at all concentrations. There were no differences in the bile acids effects on different STs. Further investigation might identify a specific bile acids' combination with inhibitory effects on C. difficile toxin and biofilm production, which could modulate toxin formation to reduce the likelihood of developing CDI.

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.

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.

Epidemiological investigation of Clostridioides difficile colonization in Chinese community infants

Clostridioides difficile is a colonizer of the human gut; asymptomatic colonization has been reported to be more common in infants and is highly variable across regions even with no symptoms of diarrhea or death. Antibiotic treatment strategies might increase the antibiotic resistance of C. difficile. We performed a one-point study involving 1098 healthy infants (0-36 months) to address the deficiency of reports on C. difficile colonization in Chinese community infants. The C. difficile colonization rate was 22.8% (250/1098), and more than half of the strains (55.2%) were toxigenic isolates. Among the 138 toxigenic isolates, 111 were of the A⁺B⁺CDT^- genotype, 26 strains were A^-B⁺CDT^-, and one strain was A⁺B⁺CDT⁺. Fifteen different PCR ribotypes were found among the 250 isolates, and PCR-ribotype HB03 appeared to be dominant type, accounting for 19.6% (49/250). High levels of resistance to antimicrobial agents were observed. Our study showed that age and hospitalization before stool collection were positively correlated with the C. difficile colonization rate, whereas the delivery term was negatively related to the colonization rate. Particular attention should be paid to the increasing resistance of C. difficile to rifamycin.

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.

Molecular epidemiology of Clostridium difficile infection in Iranian hospitals

Background

Clostridium difficile infection (CDI) is known as one of the most important causes of nosocomial infections. The main objective of this study was to evaluate the presence of Clostridium difficile in the stool of hospitalized patients with diarrhea as well as in their environments.

Methods

C. difficile isolates were characterized according to the presence of toxin genes and antibiotic resistance. Multilocus Sequence Typing Analysis (MLST) was applied for finding the genetic polymorphism and relationship among strain lineages.

Results

A total of 821 samples (574 stools and 247 swabs) were collected between April 2015 and May 2017. The prevalence of C. difficile isolates was 28.6% (164/574) in patients and 19% (47/247) in swabs taken from medical devices, hands of healthcare workers and skin patient sites. Finally, 11.5% (66/574) toxigenic C. difficile strains isolated from stool samples of inpatients and 4.4% (11/247) from hands of healthcare workers and skin patient sites. All the toxigenic isolates were inhibited by a low concentration of vancomycin (MIC < 0.5 μg/ml). About 43% (33/77) and 39% of isolates were resistant to Clindamycin and moxifloxacin respectively. All isolates were susceptible to metronidazole. Toxigenic C. difficile strains were analyzed by MLST and were divided into 4 different STs. The detected types were ST-54 (57.9%), followed by ST-2 (31.6. %), ST-15 (5.3%) and ST-37 (5.3%), while none of the isolates were identified as ST-1 or ST-11. Significant risk factors for CDI appear to be advanced age, undergoing chemotherapy, previous surgery, and residence in the nursing home.

Conclusions

CDI is common in Iran and further studies are recommended to monitor its epidemiological variations. Moreover, greater attempts must be made to encourage antibiotic stewardship by healthcare workers and the public.

Prevalence, genotype and antimicrobial resistance of Clostridium difficile isolates from healthy pets in Eastern China

BACKGROUND

Clostridium difficile (C. difficile) is a main cause of antibiotic-associated diarrhoea in humans. Several studies have been performed to reveal the prevalence rate of C. difficile in cats and dogs. However, little is known about the epidemiology of C. difficile in healthy pets in China. This study aimed to assess the burden of C. difficile shedding by healthy dogs and cats in China. Furthermore, the genetic diversity and antimicrobial susceptibility patterns of the recovered isolates were determined.

METHODS

A total of 175 faecal samples were collected from 146 healthy dogs and 29 cats. C. difficile strains were isolated and identified from the feces of these pets. The characterized C. difficile strains were typed by multilocus sequence typing (MLST), and the MICs of the isolates were determined against ampicillin, clindamycin, tetracycline, moxifloxacin, chloramphenicol, cefoxitin, metronidazole and vancomycin by the agar dilution method.

RESULTS

Overall, 3 faecal samples (1.7%) were C. difficile culture positive. One sample (0.7%) from a dog was C. difficile culture positive, while two cats (7.0%) yielded positive cultures. The prevalence rate differed significantly between cats and dogs. These isolates were typed into 3 MLST genotypes and were susceptible to chloramphenicol, tetracycline, metronidazole and moxifloxacin and resistant to ampicillin, clindamycin and cefoxitin. Notably, one strain, D141-1, which was resistant to three kinds of antibiotics and carried toxin genes, was recovered in the faeces of a healthy dog.

CONCLUSION

Our results suggest that common pets may be a source of pathogenic C. difficile, indicating that household transmission of C. difficile from pets to humans can not be excluded.

Molecular epidemiology and antimicrobial susceptibility of human Clostridium difficile isolates from a single institution in Northern China

Because the epidemiology of Clostridium difficile infection (CDI) is region-specific, the present study was undertaken to examine the epidemiology of C difficile outbreaks in Beijing, China.Eighty nonduplicate isolates were collected from March, 2016 to December, 2016. The molecular type and phylogenetic analysis were evaluated by multilocus sequence typing (MLST). The minimum inhibitory concentrations (MICs) for 11 antibiotics and the resistance mechanisms were investigated.Sixty-five toxigenic strains (81.25%), including 22 tcdABCDT strains (27.5%) and 43 tcdABCDT strains (53.75%), and also 15 nontoxigenic strains (tcdABCDT; 18.75%) were detected. MLST identified 21 different sequence types (STs), including 2 novel types (ST409 and ST416). All isolates were susceptible to metronidazole, vancomycin, fidaxomicin, piperacillin/tazobactam, and meropenem, and all were effectively inhibited by emodin (MICs 4-8 μg/mL). The resistance rates to rifaximin, ceftriaxone, clindamycin, erythromycin, and ciprofloxacin were 8.75%, 51.25%, 96.25%, 81.25%, and 96.25%, respectively; 81.25% (65/80) of isolates were multidrug-resistant. Amino acid mutations in GyrA and/or GyrB conferred quinolone resistance. One novel amino acid substitution, F86Y in GyrA, was found in 1 CIP-intermediate strain. The erm(B) gene played a key role in mediating macrolide-lincosamide-streptogramin B (MLSB) resistance. Erm(G) was also found in erm(B)-negative strains that were resistant to both erythromycin and clindamycin. RpoB mutations were associated with rifampin resistance, and 2 new amino mutations were identified in 1 intermediate strain (E573A and E603N).Regional diversity and gene heterogeneity exist in both the ST type and resistant patterns of clinical C difficile isolates in Northern China.

Prevalence of Clostridium difficile isolated from various raw meats in Korea

Clostridium difficile is an anaerobic, toxin-producing pathogen that causes human infection possibly through the consumption of meat. Clostridium difficile was isolated from 45 of 415 (10.8%) various raw meat samples collected in nationwide markets in Korea between 2013 and 2014. Among the 45 isolated strains, the highest prevalence rate was found in September (28.6%) and detected in chicken (16.4%), pork (8.3%) and beef (6.8%). According to an antibiotic resistance test, resistance was found only for clindamycin (2.2%). The genetic similarity of ribotypes O78 and O27 and strains isolated from raw meats was determined using DiversiLab. Among the isolates studied, four different rep-PCR types were identified, genetically distinct from ribotypes O78 and O27. An ELISA reaction confirmed that the two strains have toxin A and toxin B and showed 89% genetic similarity. This study suggests that food animals could be potential routes of foodborne transmission in C. difficile-associated human infection.

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.

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.

Coinfection with 2 Clostridium difficile ribotypes in China: A case report

RATIONALE

Clostridium difficile infections (CDIs) have been reported in China, but detailed clinical symptoms of coinfection by 2 C difficile ribotypes have not been documented.

PATIENTS CONCERNS

An 83-year-old male with a 10-day history of diarrhea and urinary tract infection was admitted to the hospital. The patient had received ofloxacin for several days, but his clinical response was poor. Laboratory workup revealed high white blood cell (WBC), serum creatinine (Scr), and C-reactive protein (CRP) levels. Based on these abnormal lab results, rapid detection of glutamate dehydrogenase and toxin A and B was performed.

DIAGNOSIS

Severe CDI.

INTERVENTIONS

Oral vancomycin was administered for 8 days.

OUTCOMES

Diarrhea symptoms improved and C difficile culture was negative after oral vancomycin administration for 8 days. Clostridium difficile was isolated from 3 consecutive stool samples at 2-day intervals because the patient was admitted to the hospital. Polymerase chain reaction ribotyping revealed ribotype (RT) 017 in the first 2 samples and RT 001 in the third sample. RT 017 caused significantly higher increases in the levels of WBC, Scr, and CRP than RT 001.

LESSONS

It is necessary to improve clinicians' awareness of CDI and reduce the severity of CDI caused by RT 017 in China.

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.

Simultaneous detection and characterization of toxigenic Clostridium difficile directly from clinical stool specimens

We employed a multiplex polymerase chain reaction (PCR) coupled with capillary electrophoresis (mPCR-CE) targeting six Clostridium difficile genes, including tpi, tcdA, tcdB, cdtA, cdtB, and a deletion in tcdC for simultaneous detection and characterization of toxigenic C. difficile directly from fecal specimens. The mPCR-CE had a limit of detection of 10 colony-forming units per reaction with no cross-reactions with other related bacterial genes. Clinical validation was performed on 354 consecutively collected stool specimens from patients with suspected C. difficile infection and 45 isolates. The results were compared with a reference standard combined with BD MAX Cdiff, real-time cell analysis assay (RTCA), and mPCR-CE. The toxigenic C. difficile species were detected in 36 isolates and 45 stool specimens by the mPCR-CE, which provided a positive rate of 20.3% (81/399). The mPCR-CE had a specificity of 97.2% and a sensitivity of 96.0%, which was higher than RTCA (x² = 5.67, P = 0.017) but lower than BD MAX Cdiff (P = 0.245). Among the 45 strains, 44 (97.8%) were determined as nonribotype 027 by the mPCR-CE, which was fully agreed with PCR ribotyping. Even though ribotypes 017 (n = 8, 17.8%), 001 (n = 6, 13.3%), and 012 (n = 7, 15.6%) were predominant in this region, ribotype 027 was an important genotype monitored routinely. The mPCR-CE provided an alternative diagnosis tool for the simultaneous detection of toxigenic C. difficile in stool and potentially differentiated between RT027 and non-RT027.

Preliminary screening of type IV secretion system in divergent geographic sources of Clostridium difficile

In the present study, different geographical sources and sequence types (STs) of Clostridium difficile were preliminarily screened to investigate the distribution profiles of three core genes, VirB4, VirB6 and VirD4, of the type IV secretion system (T4SS). A total of 37 C. difficile strains from different sources were screened, inoculated and prepared for genome extraction. C. difficile toxins A and B were subjected to identification and multilocus sequence typing (MLST) analysis. The T4SS gene then underwent polymerase chain reaction amplification and sequencing analysis. Of the 37 strains, 25 were toxin A- and toxin B-positive, and 12 were toxin A-negative and toxin B-positive. MLST detected 11 strains with ST37, 10 with ST2, 6 with ST35, 7 with ST3, 1 with ST54, 1 with ST1 and 1 with ST119. The detection rates of VirB4, VirB6 and VirD4 were all 100% in colonies exhibiting T4SS. Single nucleotide polymorphisms (SNPs) were detected in a minority of strains. C. difficile strains with identical STs shared the same SNP loci for T4SS, and those with different STs had different SNP loci. The results of the present study may provide evidence for subsequent identification of T4SS distribution, epidemiological investigations, polymorphism analyses and research into the association between T4SS, cytotoxicity and enterotoxication in C. difficile.

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.

Molecular Epidemiology of Clostridium difficile Infection in Hospitalized Patients in Eastern China

Few studies on risk factors for and transmission of Clostridium difficile infection (CDI) in China have been reported. A cross-sectional study was conducted for 3 years in eastern China. Consecutive stool specimens from hospitalized patients with diarrhea were cultured for C. difficile. C. difficile isolates from these patients then were analyzed for toxin genes, genotypes, and antimicrobial resistance. A severity score for the CDI in each patient was determined by a blinded review of the medical record, and these scores ranged from 1 to 6. A total of 397 out of 3,953 patients (10.0%) with diarrhea were found to have CDI. Severity of CDI was mild to moderate, and the average (± standard deviation) severity score was 2.61 ± 1.01. C. difficile was isolated from stool specimens in 432 (10.9%) of all the patients who had diarrhea. C. difficile genotypes were determined by multilocus sequence analysis and PCR ribotyping; sequence type 37 (ST37)/ribotype 017 (RT017) (n = 68, 16.5%) was the dominant genotype. Eleven patients (16.2%) with this genotype had a CDI severity score of 5. Overall, three RTs and four STs were predominant; these genotypes were associated with significantly different antimicrobial resistance patterns in comparison to all genotypes (χ² = 79.56 to 97.76; P < 0.001). Independent risk factors associated with CDI included age greater than 55 years (odds ratio [95% confidence interval], 26.80 [18.76 to 38.29]), previous hospitalization (12.42 [8.85 to 17.43]), previous antimicrobial treatment within 8 weeks (150.56 [73.11 to 310.06]), hospital stay more than 3 days before sampling (2.34 [1.71 to 3.22]), undergoing chemotherapy (3.31 [2.22 to 4.92]), and undergoing abdominal surgery (4.82 [3.54 to 6.55]). CDI is clearly a problem in eastern China and has a prevalence of 10.0% in hospitalized patients. Among risk factors for CDI, the advanced age threshold was younger for Chinese patients than that reported for patients in developed countries.

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

It has been widely reported that the incidence and severity of Clostridium difficile infection (CDI) have increased dramatically in North America and Europe. However, little is known about CDI in Mainland China. In this study, we aimed to investigate the incidence of CDI and the main epidemic and drug-resistant strains of C. difficile in Mainland China through meta-analysis of related studies published after the year 2010. A total of 51 eligible studies were included. The pooled incidence of toxigenic C. difficile among patients with diarrhoea was 14% (95% CI = 12–16%). In Mainland China, ST-37 and ST-3 were the most prevalent strains; fortunately, hypervirulent strains, such as ST-1 (BI/NAP1/027) and ST-11 (RT 078), have only occurred sporadically to date. The rates of C. difficile resistance to ciprofloxacin (98.3%; 95% CI = 96.9–99.7%), clindamycin (81.7%; 95% CI = 76.1–87.3%) and erythromycin (80.2%; 95% CI = 73.5–86.9%) are higher than in other counties; however, none of the C. difficile isolates reported in Mainland China were resistant to metronidazole (n/N = 0/960), vancomycin (n/N = 0/960), tigecycline (n/N = 0/41) or piperacillin/tazobactam(n/N = 0/288).

Molecular Epidemiology and Antimicrobial Susceptibility of Clostridium difficile Isolates from a University Teaching Hospital in China

While the developed world has seen a significant increase in the number of scientific articles on Clostridium difficile infection (CDI), the developing world still lags behind on this subject due to limited laboratory capacity, low awareness, and limited surveillance of this problem. As such, CDI is considered a neglected but potentially huge problem in developing countries. The major aim of this study was to systemically evaluate the utility of several molecular typing tools for CDI, including their relevance in epidemiological studies in developing countries such as China. A total of 116 non-repetitive toxigenic C. difficile isolates from Chinese patients, were studied. The isolates comprised 83 (71.6%) A+B+CDT- isolates, 27 (23.3%) A-B+CDT- isolates, and 6 (5.1%) A+B+CDT+ isolates. Typing methods evaluated included multilocus variable-number tandem-repeat analysis, PCR ribotyping, multilocus sequence typing, and sequencing of slpA and tcdC genes, which identified 113, 30, 22, 18, and 8 genotypes each and exhibited discriminatory powers of 0.999, 0.916, 0.907, 0.883, and 0.765, respectively. Compared to A+B+ strains, A-B+ strains exhibited higher prevalence of drug resistance to clindamycin, erythromycin, levofloxacin, rifampicin, rifaximin, and tetracycline. Furthermore, drug resistance rates of strains with different PCR ribotypes differed, supporting the importance of molecular typing in management and control of CDI. Based on our earlier suggestion to improve the diagnostic laboratory capacity of CDI in developing countries, setting up efficient surveillance programs complemented by relevant molecular typing methods is warranted.

Clostridium difficile-associated clinical burden from lack of diagnostic testing in a Chinese tertiary hospital

Despite Clostridium difficile infection (CDI) being a common cause of diarrhoea in hospitals worldwide, diagnostic testing or management guidelines are not available in most hospitals in China. In this prospective two-year study, the incidence of CDI among 276 patients with watery diarrhoea was 23.1%. Lack of diagnostic testing for CDI was associated with improper management in 26.4% of patients, risk of nosocomial transmission from lack of isolation precautions, and risk of community transmission from discharging symptomatic toxigenic C. difficile carriers. Updating practice guidelines in line with the current evidence and implementing diagnostic testing for CDI are recommended in hospitals in China.

CdtR Regulates TcdA and TcdB Production in Clostridium difficile

Clostridium difficile is a global health burden and the leading cause of antibiotic-associated diarrhoea worldwide, causing severe gastrointestinal disease and death. Three well characterised toxins are encoded by this bacterium in two genetic loci, specifically, TcdB (toxin B) and TcdA (toxin A) in the Pathogenicity Locus (PaLoc) and binary toxin (CDT) in the genomically distinct CDT locus (CdtLoc). Toxin production is controlled by regulators specific to each locus. The orphan response regulator, CdtR, encoded within the CdtLoc, up-regulates CDT production. Until now there has been no suggestion that CdtR influences TcdA and TcdB production since it is not carried by all PaLoc-containing strains and CdtLoc is not linked genetically to PaLoc. Here we show that, in addition to CDT, CdtR regulates TcdA and TcdB production but that this effect is strain dependent. Of clinical relevance, CdtR increased the production of TcdA, TcdB and CDT in two epidemic ribotype 027 human strains, modulating their virulence in a mouse infection model. Strains traditionally from animal lineages, notably ribotype 078 strains, are increasingly being isolated from humans and their genetic and phenotypic analysis is critical for future studies on this important pathogen. Here we show that CdtR-mediated toxin regulation did not occur in other strain backgrounds, including a ribotype 078 animal strain. The finding that toxin gene regulation is strain dependent highlights the regulatory diversity between C. difficile isolates and the importance of studying virulence regulation in diverse lineages and clinically relevant strains. Our work provides the first evidence that TcdA, TcdB and CDT production is linked by a common regulatory mechanism and that CdtR may act as a global regulator of virulence in epidemic 027 strains.

Clostridium difficile is the leading cause of antibiotic-associated diarrhoea. The TcdB, TcdA and binary toxins produced by C. difficile are encoded in two genomically distinct loci: TcdB and TcdA in the Pathogenicity Locus (PaLoc) and binary toxin (CDT) in the CDT locus (CdtLoc). Toxin production is primarily controlled by regulators specific to each locus. Because the presence of these loci varies amongst different strains of C. difficile, no rational link for their co-regulation has ever been proposed. Here we have shown that the regulator of CDT production, CdtR, also regulates production of TcdA and TcdB in a strain dependent manner. These results represent the first evidence that TcdA and TcdB production is linked to the production of CDT by a common regulatory mechanism. Collectively, our results establish CdtR as an important virulence regulator in two clinically important, epidemic strains of C. difficile, and further highlights the need to investigate regulatory mechanisms of important virulence factors in diverse strain backgrounds.

Genome Sequence and Analysis of Peptoclostridium difficile Strain ZJCDC-S82

Peptoclostridium difficile (Clostridium difficile) is the major pathogen associated with infectious diarrhea in humans. Concomitant with the increased incidence of C. difficile infection worldwide, there is an increasing concern regarding this infection type. This study reports a draft assembly and detailed sequence analysis of C. difficile strain ZJCDC-S82. The de novo assembled genome was 4.19 Mb in size, which includes 4,013 protein-coding genes, 41 rRNA genes, and 84 tRNA genes. Along with the nuclear genome, we also assembled sequencing information for a single plasmid consisting of 11,930 nucleotides. Comparative genomic analysis of C. difficile ZJCDC-S82 and two other previously published strains, such as M120 and CD630, showed extensive similarity. Phylogenetic analysis revealed that genetic diversity among C. difficile strains was not influenced by geographic location. Evolutionary analysis suggested that four genes encoding surface proteins exhibited positive selection in C. difficile ZJCDC-S82. Codon usage analysis indicated that C. difficile ZJCDC-S82 had high codon usage bias toward A/U-ended codons. Furthermore, codon usage patterns in C. difficile ZJCDC-S82 were predominantly affected by mutation pressure. Our results provide detailed information pertaining to the C. difficile genome associated with a strain from mainland China. This analysis will facilitate the understanding of genomic diversity and evolution of C. difficile strains in this region.

Molecular characterization and antimicrobial susceptibility of tcdA-negative Clostridium difficile isolates from Guangzhou, China

This study aimed to investigate the molecular characteristics and antimicrobial susceptibility of Clostridium difficile clinical isolates in Guangzhou, China. One hundred twenty isolates were collected from Guangzhou General Hospital at the Guangzhou Military Command in China from March 2014 to April 2015, and 9 isolates were identified as tcdA-negative/tcdB-positive (A(-)B(+)) strains. Results showed that all of the strains were confirmed to be ST37 and 0 single nucleotide variants (SNVs) were found in the PaLoc region, and >60 SNVs were identified throughout the whole genome sequence. The results show the diversity of the antibiotic and gene mutations present in these strains. All of the A(-)B(+) isolates were highly resistant to clindamycin and erythromycin; showed an average sensitivity to fluoroquinolones; and maintained a high susceptibility to metronidazole, vancomycin, and tigecycline.

The Role of Glutamate Dehydrogenase (GDH) Testing Assay in the Diagnosis of Clostridium difficile Infections: A High Sensitive Screening Test and an Essential Step in the Proposed Laboratory Diagnosis Workflow for Developing Countries like China

The incidence and severity of Clostridium difficile infection (CDI) in North America and Europe has increased significantly since the 2000s. However, CDI is not widely recognized in China and other developing countries due to limited laboratory diagnostic capacity and low awareness. Most published studies on laboratory workflows for CDI diagnosis are from developed countries, and thus may not be suitable for most developing countries. Therefore, an alternative strategy for developing countries is needed. In this study, we evaluated the performance of the Glutamate Dehydrogenase (GDH) test and its associated workflow on 416 fecal specimens from suspected CDI cases. The assay exhibited excellent sensitivity (100.0%) and specificity (92.8%), compared to culture based method, and thus could be a good screening marker for C. difficile but not for indication of toxin production. The VIDAS CDAB assay, which can detect toxin A/B directly from fecal specimens, showed good specificity (99.7%) and positive predictive value (97.2%), but low sensitivity (45.0%) and negative predictive value (88.3%), compared with PCR-based toxin gene detection. Therefore, we propose a practical and efficient GDH test based workflow strategy for the laboratory diagnosis of CDI in developing countries like China. By applying this new workflow, the CDI laboratory diagnosis rate was notably improved in our center, yet the increasing cost was kept at a minimum level. Furthermore, to gain some insights into the genetic population structure of C. difficile isolates from our hospital, we performed MLST and PCR toxin gene typing.

Molecular Epidemiology of Clostridium difficile Infection in a Large Teaching Hospital in Thailand

Clostridium difficile infection (CDI) is a leading cause of healthcare-associated morbidity and mortality worldwide. In Thailand, CDI exhibits low recurrence and mortality and its molecular epidemiology is unknown. CDI surveillance was conducted in a tertiary facility (Siriraj Hospital, Bangkok). A total of 53 toxigenic C. difficile strains from Thai patients were analyzed by multi-locus sequence typing (MLST), PCR ribotyping, and pulse-field gel electrophoresis (PFGE). The mean age of the cohort was 64 years and 62.3% were female; 37.7% of patients were exposed to > two antibiotics prior to a diagnosis of CDI, with beta-lactams the most commonly used drug (56.3%). Metronidazole was used most commonly (77.5%; success rate 83.9%), and non-responders were treated with vancomycin (success rate 100%). None of the isolates carried binary toxin genes. Most isolates (98.2–100%) were susceptible to metronidazole, vancomycin, tigecycline and daptomycin. There were 11 sequence types (STs), 13 ribotypes (RTs) and four PFGE types. Six previously identified STs (ST12, ST13, ST14, ST33, ST41 and ST45) and five novel STs unique to Thailand (ST66, ST67, ST68, ST69 and ST70) were identified. PCR RTs UK 017 (ST45) (45.3%) and UK 014/020 (ST33) (24.5%) were the most common. High concordance was observed between the MLST and ribotyping results (p<0.001). C. difficile isolates from Thai patients were highly susceptible to standard antimicrobial agents. In conclusion, the five STs indicate the high genetic diversity and unique polymorphisms in Thailand. Moreover, the emergence of antimicrobial resistance to vancomycin warranted continuous surveillance to prevent further spread of the toxigenic C. difficile isolates.

Molecular epidemiology and antimicrobial susceptibility of Clostridium difficile isolated from a university teaching hospital in Japan

Clostridium difficile infection control strategies require an understanding of its epidemiology. In this study, we analysed the toxin genotypes of 130 non-duplicate clinical isolates of C. difficile from a university hospital in Tokyo, Japan. Multilocus sequence typing (MLST) and eBURST analysis were performed for these isolates and nine strains previously analysed by polymerase chain reaction (PCR) ribotyping. Minimum inhibitory concentrations (MICs) were determined for six antibiotics, and the bacterial resistance mechanisms were investigated. Ninety-five toxigenic strains (73%), including seven tcdA-negative, tcdB-positive and cdtA/cdtB-negative strains (A(-)B(+)CDT(-)) and three A(+)B(+)CDT(+) strains, and 35 (27%) non-toxigenic strains, were classified into 23 and 12 sequence types, respectively. Of these, sequence type (ST)17 (21.8%) was the most predominant. MLST and eBURST analysis showed that 139 strains belonged to seven groups and singletons, and most A(+)B(+)CDT(-) strains (98%, 89/91) were classified into group 1. All isolates were susceptible to metronidazole, vancomycin and meropenem; the ceftriaxone, clindamycin and ciprofloxacin resistance rates were 49, 59 and 99%, respectively. Resistance rates to ceftriaxone and clindamycin were higher in toxigenic strains than in non-toxigenic strains (P < 0.001). All ST17 and ST81 strains were resistant to these antibiotics. The clindamycin- and fluoroquinolone-resistant strains carried erm(B) and mutations in GyrA and/or GyrB, respectively. To our knowledge, this is the first MLST-based study of the molecular epidemiology of toxigenic and non-toxigenic strains in Japan, providing evidence that non-toxigenic and toxigenic strains exhibit high genetic diversity and that toxigenic strains are more likely than non-toxigenic strains to exhibit multidrug resistance.

ICU-Onset Clostridium difficile infection in a university hospital in China: a prospective cohort study

A prospective study was conducted to investigate the incidence, clinical profiles and outcome of ICU-onset CDI in a 50-bed medical ICU at a university hospital in China. Stools were collected from patients who developed ICU-onset diarrhea and was screened for tcdA (toxin A gene) and tcdB (toxin B gene) by PCR. CDI cases were compared with the ICU-onset non-CDI diarrhea cases for demographics, comorbidities, potential risk factors, major laboratory findings and outcomes. Stool samples from CDI cases were subjected to C. difficile culture and C. difficile isolates were screened for tcdA, tcdB and the binary toxin genes (cdtA and cdtB) using multiplex PCR. Strain typing of toxigenic C. difficile isolates was performed using multilocus sequence typing. There were 1,277 patients in the ICU during the study period and 124 (9.7%) developed ICU-onset diarrhea, of which 31 patients had CDI. The incidence of ICU-onset CDI was 25.2 cases per 10,000 ICU days. ICU-onset CDI cases had similar features with ICU-onset non-CDI diarrhea cases including the use of proton pump inhibitors and antibacterial agents. The crude mortality rate of ICU-onset CDI was 22.6%, but the attributable mortality rate of ICU-onset CDI was only 3.2% here. Toxigenic C. difficile isolates were recovered from 28 out of the 31 patients with CDI. cdtA and cdtB were found in two strains. Seventeen STs including 11 new STs were identified. All of the 11 new STs were single-locus variants of known STs and the 17 STs identified here could be clustered into 3 clades. The incidence of ICU-onset CDI here is similar to those in Europe and North America, suggesting that CDI is likely to be a common problem in China. Toxigenic C. difficile here belonged to a variety of STs, which may represent a significant clonal expansion rather than the true clonal diversity.

Risk factors of Clostridium difficile infections among patients in a university hospital in Shanghai, China

Clostridium difficile infection (CDI) is an increasing concern in China. However, the risk factors of CDI are rarely reported in the Chinese population. A prospective observational study was therefore conducted among patients with hospital-acquired C. difficile diarrhoea and the risk factors of CDI in a retrospective case-control study. The CDI patients were compared with the non-CDI diarrhoeal patients and those without diarrhoea, respectively. The recurrent CDI patients were compared with the corresponding non-recurrent CDI patients and those without diarrhoea, respectively. Overall, of the 240 patients with hospital-acquired diarrhoea 90 (37.5%) were diagnosed as CDI, and 12 (13.3%) of the 90 CDI patients experienced recurrence. Multivariate analysis indicated that renal disease, malignancy, hypoalbuminemia, prior antibiotic treatment, chemotherapy, nasogastric tube use, length of stay>14 days and intra-abdominal surgery, defined daily dose of antimicrobial agents≥19, prior use of more than three antimicrobial agents, and use of carbapenems were independent risk factors for the first episode of CDI. Use of laxatives, the first- and second-generation narrow-spectrum cephalosporins or metronidazole was identified as protective factors. It is necessary to make testing of C. difficile available as a routine practice and control these risk factors in Chinese hospitals to avoid CDI outbreaks.

Sequence variation in tcdA and tcdB of Clostridium difficile: ST37 with truncated tcdA is a potential epidemic strain in China

Clostridium difficile is a well-known nosocomial infectious pathogen. Research on C. difficile infection has primarily focused on strains such as the hypervirulent PCR ribotype 027 (sequence type 1 [ST1]) emerging in Europe and North America. However, other new emerging ribotypes in some countries have attracted attention, such as PCR ribotype 17 (ST37) in Asia and Latin America. We collected 70 strains and sequenced their toxin genes, tcdA and tcdB. Multilocus sequence typing (MLST) was used to study their population structure. In addition, tcdA and/or tcdB sequences of 25 other isolates were obtained from GenBank. Single nucleotide polymorphisms (SNPs) were identified and analyzed. Phylogenetic analyses were performed to study toxin gene evolution. All tcdA and tcdB sequences were divided into 1 of 16 types (denoted A01 to -16 and B01 to -16, respectively). Hypervirulent strain RT027 is A13B12, and RT078 is A14B10, whereas the newly epidemic strain RT017 is A15B13. SNP analysis suggests the possibility of recombination in tcdB, perhaps through horizontal gene transfer. SNPs were also found in the sequences corresponding to the PCR primers widely used for toxin detection. Our study shows that ST037 shares a few genotypic features in its tcdA and tcdB genes with some known hypervirulent strains, indicating that they fall into a unique clade. Our findings can be used to map the relationships among C. difficile strains more finely than can be done with less sensitive methods, such as toxinotyping or even MLST, to reveal their inherent epidemiological characteristics.

Clinical characteristics of Clostridium difficile infection in hospitalized patients with antibiotic-associated diarrhea in a university hospital in China

The purpose of this study was to identify clinical characteristics of Clostridium difficile infection (CDI) in patients with antibiotic-associated diarrhea (AAD). A prospective study was conducted among patients hospitalized in Fudan University Hospital Huashan from August 1, 2012 to July 31, 2013. Toxigenic C. difficile isolates were characterized by PCR ribotyping and multilocus sequence typing. AAD developed in 1.0 % (206/20437) of the antibiotic-treated hospitalized patients and toxigenic C. difficile was isolated from 30.6 % (63/206) of patients with AAD. The frequency of AAD was highest in the intensive care unit (10.7 %); however the proportion of CDI in AAD was highest in the Geriatric Unit (38 %). AAD ranged in severity from mild to moderate. One case with pseudomembranous colitis was identified. Use of carbapenems was found to significantly increase the risk of CDI (OR, 2.31; 95 % CI, 1.22-4.38; p = 0.011). Patient demographics, presumed risk factors, clinical manifestations and laboratory findings revealed no significant difference between patients with CDI and non-C. difficile AAD. Over 90 % of the patients with CDI or non-C. difficile AAD were cured. Two patients had CDI recurrence. Ribotype H was the dominant (18.8 %) genotype, followed by ribotype 012 and ribotype 017. C. difficile plays a significant role in AAD in our setting in China. Because the severity of diarrhea ranges from mild to moderate, it is difficult for Chinese clinicians to identify CDI from AAD patients, therefore CDI should be included in the routine differential diagnoses for hospitalized patients presenting with AAD.

Molecular epidemiology of Clostridium difficile in a tertiary hospital of China

Clostridium difficile infection (CDI) is caused by toxin-producing strains. It accounts for 20-30 % of antibiotic-associated diarrhoea and particularly accounts for 90 % of pseudomembranous colitis. The epidemiological study of C. difficile is thus important. In this study, we report the molecular epidemiology and ward distribution of C. difficile in a tertiary hospital of China. A total of 161 toxigenic strains were isolated from 1845 patients originating from different wards and the strains were characterized based on toxin profile and multilocus sequence typing. Variable isolation rates were observed in different wards and the occurrence was higher in intensive care unit and geriatric wards. Toxin gene profiling revealed that, out of the 161 isolates, 134 (83.2)% were positive for both toxin A (tcdA) and toxin B (tcdB) (A+B+) followed by toxin A-negative and B-positive (A-B+) (16.8 %) isolates. However, only three of the toxigenic strains (1.9 %) were positive for both the cdtA and cdtB genes. Based on the molecular epidemiology study, a total of 30 different sequence types (STs), including one new ST (ST-220), were distinguishable. ST-54 was the most prevalent (23.0 %), followed by ST-35 (19.3 %) and ST-37 (10.0 %). None of the isolates belonged to ST-1 (ribotype 027) or ST-11 (ribotype 078). Taken together, the toxin profile and the molecular epidemiological data showed that all the ST-37 clades were of toxin type A-B+, which accounted for 59.3 % of all type A-B+ isolates. Meanwhile the clade 1 genotype, ST-54, was widely distributed among the geriatric, infection and haematology wards. There was no outbreak of C. difficile infection during our study; however the possibility of prolonged outbreaks cannot be completely ignored.

Overview of Clostridium difficile infection: implications for China

The incidence and severity of Clostridium difficile infection (CDI) have dramatically increased in the Western world in recent years. In contrast, CDI is rarely reported in China, possibly due to under-diagnosis. This article briefly summarizes CDI incidence, management and preventive strategies. The authors intend to raise awareness of this disease among Chinese physicians and health workers, in order to minimize the medical and economic burden of a potential epidemic in the future.

Concurrent infections of Giardia duodenalis, Enterocytozoon bieneusi, and Clostridium difficile in children during a cryptosporidiosis outbreak in a pediatric hospital in China

Background

Over 200 cryptosporidiosis outbreaks have been reported, but little is known if other enteric pathogens were also involved in some of these outbreaks. Recently, an outbreak of cryptosporidiosis linked to poor hygiene by two Cryptosporidium hominis subtypes occurred in a pediatric hospital ward (Ward A) in China, lasting for more than 14 months. In this study, the concurrence during the outbreak of three other enteric pathogens with a similar transmission route, Giardia duodenalis, Enterocytozoon bieneusi, and Clostridium difficile, was assessed.

Methods/Principal Findings

The occurrence of G. duodenalis, E. bieneusi, and C. difficile in 78 inpatients from Ward A and 283 and 216 inpatients from two control wards (Wards C and D) in the same hospital was examined using molecular diagnostic tools. Significantly higher infection rates were found in children in Ward A for all study pathogens than in Wards C and D (P<0.01): 9.5% versus 1.4% and 0% for G. duodenalis, 10.8% versus 2.8% and 3.7% for E. bieneusi, and 60.8% versus 37.8% and 27.8% for C. difficile, respectively. These differences were mostly seen in children ≤12 months. Enteric pathogen-positive children in Ward A (31/58 or 53.4%) were more likely to have mixed infections than those in Ward C (4/119 or 3.4%) or D (5/68, 7.4%; P<0.01). Having cryptosporidiosis was a risk factor for G. duodenalis (OR = 4.3; P = 0.08), E. bieneusi (OR = 3.1; P = 0.04), and C. difficile (OR = 4.7; P<0.01) infection. In addition, a lower diversity of G. duodenalis, E. bieneusi, and C. difficile genotypes/subtypes was observed in Ward A.

Conclusions/Significance

Data from this study suggest that multiple pathogens were concurrently present during the previous cryptosporidiosis outbreak. Examination of multiple enteric pathogens should be conducted when poor hygiene is the likely cause of outbreaks of diarrhea.

The transmission of Giardia duodenalis, Enterocytozoon bieneusi, and Clostridium difficile is poorly understood in developing countries despite their wide occurrence. Because they are transmitted by the same fecal-oral route as Cryptosporidium, in this study, we have examined the occurrence of these enteric pathogens in children during a cryptosporidiosis outbreak in a pediatric hospital in China. Using molecular diagnostic tools, we have detected significantly higher infection rates of these enteric pathogens in the outbreak ward than in two control wards in the same hospital. We have also shown a much higher occurrence of these pathogens in children having cryptosporidiosis than those having no cryptosporidiosis. We have demonstrated that the genetic diversity of enteric pathogens is much lower in the outbreak ward than in control wards. Therefore, other enteric pathogens are concurrently present during the cryptosporidiosis outbreak, and examinations for multiple enteric pathogens should be conducted when poor hygiene is considered the likely cause of outbreaks of diarrhea.

Molecular epidemiology of Clostridium difficile infection in a major chinese hospital: an underrecognized problem in Asia?

Clostridium difficile infection is almost unrecognized in mainland China. We have undertaken a study in a large Chinese teaching hospital in Changsha, Hunan, China, to identify cases of C. difficile, record patient characteristics, and define the molecular epidemiology with respect to ribotype distribution and cross-infection. Between April 2009 and February 2010, we examined fecal samples from 70 hospitalized patients with diarrhea who were receiving or had received antibiotics within the previous 6 weeks. Clinical information was collected and the samples were cultured for C. difficile retrospectively. Isolates were ribotyped, and multiple-locus variable-number tandem-repeat assay (MLVA) subtyping was performed on clusters of the same ribotype. The mean age of patients from whom C. difficile was cultured was 58 years, with only 4/21 patients aged >65 years. All patients, with a single exception, had received a third-generation cephalosporin and/or a quinolone antibiotic. Twenty-one isolates of C. difficile were recovered, and seven different ribotypes were identified, the dominant types being 017 (48%), 046 (14%), and 012 (14%). We identified two clusters of cross-infection with indistinguishable isolates of ribotype 017, with evidence of spread both within and between wards. We have identified C. difficile as a possibly significant problem, with cross-infection and a distinct ribotype distribution, in a large Chinese hospital. C. difficile may be underrecognized in China, and further epidemiological studies across the country together with the introduction of routine diagnostic testing are needed to ascertain the size of this potentially significant problem.

Epidemiology of Clostridium difficile infection in Asia

While Clostridium difficile infection (CDI) has come to prominence as major epidemics have occurred in North America and Europe over the recent decade, awareness and surveillance of CDI in Asia have remained poor. Limited studies performed throughout Asia indicate that CDI is also a significant nosocomial pathogen in this region, but the true prevalence of CDI remains unknown. A lack of regulated antibiotic use in many Asian countries suggests that the prevalence of CDI may be comparatively high. Molecular studies indicate that ribotypes 027 and 078, which have caused significant outbreaks in other regions of the world, are rare in Asia. However, variant toxin A-negative/toxin B-positive strains of ribotype 017 have caused epidemics across several Asian countries. Ribotype smz/018 has caused widespread disease across Japan over the last decade and more recently emerged in Korea. This review summarises current knowledge on CDI in Asian countries.