Fulminant colitis from Clostridium difficile infection, the epidemic strain ribotype 027, in Japan

The gut microbiome diversity of Clostridioides difficile-inoculated mice treated with vancomycin and fidaxomicin

OBJECTIVE

To investigate the effect of vancomycin and fidaxomicin on the diversity of intestinal microbiota in a mouse model of Clostridioides difficile infection.

METHODS

Mice were divided into 11 models (4 mice per model): 6 uninoculated models and 5 models inoculated with C. difficile BI/NAP1/027. Inoculated models were prepared using intraperitoneal clindamycin followed by inoculation with C. difficile BI/NAP1/027. Uninoculated and C. difficile-inoculated mice received 2 or 7 days' vancomycin or fidaxomicin. Clostridium butyricum MIYAIRI 588 probiotic and lactoferrin prebiotic were administered for 10 days to uninoculated mice. Intestinal microbiome composition was investigated by sequence analyses of bacterial 16S rRNA genes from faeces, and microbiota diversity estimated.

RESULTS

In uninoculated, untreated ('normal') mice, Clostridia (57.8%) and Bacteroidia (32.4%) accounted for the largest proportions of gut microbiota. The proportion of Clostridia was numerically reduced in C. difficile-inoculated versus normal mice. Administration of vancomycin to C. difficile-inoculated mice reduced the proportions of Bacteroidia and Clostridia, and increased that of Proteobacteria. Administration of fidaxomicin to C. difficile-inoculated mice reduced the proportion of Clostridia to a lesser extent, but increased that of Bacteroidia. Microbiota diversity was lower in C. difficile-inoculated versus normal mice (164.5 versus 349.1 operational taxonomic units (OTUs), respectively); treatment of C. difficile-inoculated mice with 7 days' vancomycin reduced diversity to a greater extent than did 7 days' fidaxomicin treatment (26.2 versus 134.2 OTUs, respectively).

CONCLUSIONS

Both C. difficile inoculation and treatment with vancomycin or fidaxomicin reduced microbiota diversity; however, dysbiosis associated with fidaxomicin was milder than with vancomycin.

Hypervirulent clade 2, ribotype 019/sequence type 67 Clostridioides difficile strain from Japan

Background

Clostridioides difficile ribotype (RT) 019/sequence type (ST) 67 strains belong to a hypervirulent lineage closely related to RT027/ST1; however, limited data are available for hypervirulent clade 2 lineages in Japan. Herein, we report the draft genome of a C. difficile strain B18-123 belonging to clade 2, RT019/ST67 for the first time in Japan.

Results

The pathogenicity locus carried by B18-123 (19.6 kb) showed higher homology (97.29% nucleotide identity) with strain R20291 (RT027/ST1) than the reference strain 630 (RT012/ST54), and B18-123 harbored 8-nucleotide substitutions in tcdC. However, it did not contain an 18-base pair (bp) deletion or a single-bp deletion at position 117 in tcdC, which was identified in the previous strain R20291. A cytotoxicity assay revealed similar cytotoxicity levels between strains B18-123 and ATCC BAA-1870 (RT027/ST1). The B18-123 strain was found to be susceptible to metronidazole and vancomycin.

Conclusion

Our findings contribute to the further understanding of the characteristics of hypervirulent clade 2 including RT019/ST67 lineages.

Molecular epidemiologic study of Clostridium difficile infections in university hospitals: Results of a nationwide study in Japan

We conducted a nationwide molecular epidemiological study of Clostridium difficile infection (CDI) in Japan investigated the correlation between the presence of binary toxin genes and CDI severity. This is the first report on molecular epidemiological analyses for CDI in multiple university hospitals in Japan, to our knowledge. We examined 124,484 hospitalized patients in 25 national and public university hospitals in Japan between December 2013 and March 2014, investigating antimicrobial susceptibilities and toxin-related genes for C. difficile isolates from stools. Epidemiological genetic typing was performed by PCR-ribotyping and repetitive sequence-based (rep)-PCR to examine the genetic similarities. The results detected toxin A-positive, toxin B-positive, binary toxin-negative (A⁺B⁺CDT^-) detected from 135 isolates (80.8%) and toxin A-negative, toxin B-positive, binary toxin-negative (A^-B⁺CDT^-) in 23 (13.8%). Toxin A-positive, toxin B-positive, and binary toxin-positive (A⁺B⁺CDT⁺) were seen in 9 isolates (5.4%). Vancomycin (n = 81, 37.7%) or metronidazole (n = 88, 40.9%) therapies were undertaken in analyzed cases. Ribotypes detected from isolates were 017/subgroup 1, 070, 078, 126, 176, 449, 475/subgroup 1, 499, 451, 566 and newtypes. Rep-PCR classified 167 isolates into 28 cluster groups including 2-15 isolates. In addition, 2 pairs of strains isolated from different institutions belonged to the same clusters. Seven out of 9 (77.8%) of the patients with binary toxin producing strains had "mild to moderate" outcome in evaluated symptoms. In conclusion, we found that binary toxin did not show regional specificity and had no relevance to severity of CDI.

The First Two Clostridium difficile Ribotype 027/ST1 Isolates Identified in Beijing, China-an Emerging Problem or a Neglected Threat?

Clostridium difficile hyper-virulent ribotype 027 strain has become a significant concern globally, but has rarely been reported in Asian countries including China. Recently, a retrospective single-center study in Beijing, China, detected two ribotype 027 C. difficile isolates from two patients coming for outpatient visits in 2012 and 2013. We performed a systematic investigation of the two isolates (and patients). Both C. difficile isolates had the typical PCR ribotype 027 profile; were positive for tcdA, tcdB and binary toxin genes; belonged to multilocus sequence type 1 (ST1); had typical ribotype 027 deletions in the tcdC gene; and were highly-resistant to fluoroquinolones; but had a different MLVA profile and were not genetically related to any previously reported international ribotype 027 clones. A review of the patients' medical records showed that neither received appropriate antimicrobial treatment and were lost to follow-up after outpatient visits. We propose that C. difficile infections caused by ribotype 027 are probably a neglected problem in China, and the subsequent impact of unawareness of this problem is worrying. Appropriate testing assays and multi-center or national level surveillance for C. difficile infections and specifically for ribotype 027 should be introduced to provide essential data and guide future clinical practice.

Clinical characteristics and risk factors for community-acquired Clostridium difficile infection: A retrospective, case-control study in a tertiary care hospital in Japan

The epidemiology of Clostridium difficile infection (CDI) has changed in the past decade. The incidence, prevalence, and severity of community-acquired CDI (CA-CDI) have increased. However, the epidemiology of CA-CDI in Japan has not been investigated. To evaluate the clinical characteristics and risk factors for CA-CDI in Japan, we conducted a retrospective, case-control study of CA-CDI at the National Hospital Organization Tokyo Medical Center between January 2010 and December 2014. Two age- and sex-matched C. difficile toxin- and culture-negative controls were assigned for each case. A total of 26 patients were identified with CA-CDI were identified. The incidence rate for CA-CDI was 1.4 per 100,000 patient-years. Of the CA-CDI patients, 6 (23.1%) had no underlying comorbidity, 22 (84.6%) had prior exposure to antimicrobials, and 5 (19.2%) had prior exposure to antacids. Although 5 patients (19.2%) required hospitalization, none required intensive care or died. Recurrence was observed in 1 patient (3.8%). Patients with CA-CDI cases were more likely to have been recently exposed to antimicrobials compared to controls (odds ratio [OR]: 8.12, 95% confidence interval [CI]: 2.43-26.98). However, exposure to antacids was not associated with CA-CDI (OR: 0.59, 95% CI: 0.19-1.85). Our findings indicate that the incidence rate for CA-CDI in Japan is relatively low compared to the US and Europe, and that CA-CDI is usually not severe. Previous antimicrobial exposure was the main risk factor for CA-CDI, suggesting that clinicians should consider CDI in patients presenting with diarrhea who have recently received antimicrobials.

Incorrect diagnosis of Clostridium difficile infection in a university hospital in Japan

Physicians often fail to suspect Clostridium difficile infection (CDI) and many microbiology laboratories use suboptimal diagnostic techniques. To estimate the extent of and reasons for incorrect diagnosis of CDI in Japan, we investigated toxigenic C. difficile isolated from all stool culture samples and clinical course. Over a 12-month period in 2010, all stool culture samples (n = 975) submitted from inpatients in a university hospital in Japan were cultured for C. difficile and routine microbiological testing was conducted. In total, 177 C. difficile isolates were recovered, and 127 isolates were toxigenic. Among the toxin-A-positive/toxin-B-positive isolates, 12 were also positive for the binary toxin gene. However, clinically important ribotypes, such as 027 and 078, were not identified. A total of 58 (45.7%) cases with toxigenic C. difficile had unformed stool, and the incidence CDI was 1.6 cases per 10,000 patient-days. Of these 58 cases, 40 were not diagnosed in routine testing due to a lack of clinical suspicion (24.1%, 14/58) or a negative C. difficile toxin assay result (44.8%, 26/58). A stool toxin assay was performed in 54 patients (78.2%, 54/69) who did not have unformed stool. The present study demonstrated that a significant number of CDI cases in Japan might be overlooked or misdiagnosed in clinical practice due to a lack of clinical suspicion and limitations of microbiological testing for CDI in Japan. Providing education to promote awareness of CDI among physicians is important to improve the accuracy of diagnosis in Japan.

Multi-institution case-control and cohort study of risk factors for the development and mortality of Clostridium difficile infections in Japan

OBJECTIVE

To examine risk factors for Clostridium difficile infection (CDI) morbidity and mortality in Japan.

DESIGN

Multimethod investigation including a case-control study and cohort study.

SETTING

47 participating facilities of the National Hospital Organization (NHO).

PARTICIPANTS

1026 patients with CDI and 878 patients in the control group over the age of 18 years admitted to the subject NHO facilities from November 2010 to October 2011.

MAIN OUTCOME MEASURES

In a case-control study, we identify risk factors for CDI development. Next, in a cohort study, we identify risk factors for all-cause mortality within 30 days following CDI onset.

RESULTS

A total of 1026 cases of CDI meeting the definitions of this investigation were identified, encompassing 878 patients at 42 of the 47 subject facilities. In the case-control study, we identified, compared with no antibiotics use, use of first-generation and second-generation cephem antibiotics (OR 1.44; 95% CI 1.10 to 1.87), use of third-generation and fourth-generation cephem antibiotics (OR 1.86; 95% CI 1.48 to 2.33) and use of carbapenem antibiotics (OR 1.87; 95% CI 1.44 to 2.42) the risk factors for CDI development. However, use of penicillin was not identified as a risk factor. In the cohort study, sufficient data for analysis was available for 924 CDI cases; 102 of them (11.0%) resulted in death within 30 days of CDI onset. Compared with no anti-CDI drug use, use of vancomycin was associated with reduced risk of mortality (OR 0.43; 95% CI 0.25 to 0.75) whereas metronidazole was not.

CONCLUSIONS

The findings mirror those of previous studies from Europe and North America, identifying the administration of broad-spectrum antibiotics as a risk factor for CDI development. The use of vancomycin is associated with a decreased risk of mortality.

Fulminant pseudomembranous colitis caused by Clostridium difficile PCR ribotype 027 in a healthy young woman in Japan

In the past two decades, Clostridium difficile polymerase chain reaction ribotype 027 strain has rapidly emerged as the leading cause of antibiotic-associated colitis in North America and Europe; however, it has been reported only occasionally in Japan. We report a case of fulminant pseudomembranous colitis caused by this strain in a healthy young woman in Japan without any previous medical history. The strain isolated from our patient was susceptible to both gatifloxacin and moxifloxacin, thus representing a historic strain. The acquisition of fluoroquinolone resistance was reported as the important key genetic event linked to the virulence of this strain. It is noteworthy that the fluoroquinolone-susceptible 027 strain caused fulminant colitis in a healthy young woman in a non-endemic area. Our experience suggests that C. difficile PCR ribotype 027 has the potential virulence factors that are not associated with a fluoroquinolone resistance-conferring mutation.