Prevalence of toxin A-nonproducing/toxin-B-producing Clostridium difficile in the Tsukuba-Tsuchiura district, Japan

The Epidemiology of Clostridium difficile Infection in Japan: A Systematic Review

Abstract

To increase understanding of the epidemiology, risks, consequences and resource utilization of Clostridium difficile infection (CDI) in Japan, a systematic literature review was undertaken of relevant publications from January 2006 to November 2017. Using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and methods, 55 articles met the criteria for full review. The majority (58%) of studies were from a single site, with the most recent data from 2015. The incidence, reported prevalence and recurrence rate of CDI in Japan were 0.8–4.71/10,000 patient-days, 0.3–5.5/1000 patients and 3.3–27.3%, respectively, and varied according to setting, population, CDI definition and detection method. Most C. difficile isolates associated with CDI in Japan were toxin A+B+, with a low level of C. difficile binary toxin-positive (CDT+) strains (0–6.8% reported across studies). The most common C. difficile PCR ribotypes associated with infection in Japan were smz/018, 002, 052 and 369. Data regarding the impact of CDI on length of hospital stay were limited. Reported all-cause mortality in patients with CDI ranged from 3.4 to 15.1% between 2007 and 2013. Two studies assessed risk factors for CDI recurrence, identifying malignant disease, intensive care unit hospitalization and use of proton pump inhibitors as factors increasing the risk of initial and/or recurrent CDI. No study analyzed initial CDI treatment in relation to recurrence. More comprehensive surveillance and coordinated studies are needed to map trends, understand risk factors, and recognize the extent and impact of CDI in Japanese patients.

Funding

Astellas Pharma, Inc.

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Electronic supplementary material

The online version of this article (10.1007/s40121-018-0186-1) contains supplementary material, which is available to authorized users.

Performance evaluation of the Verigene®Clostridium difficile nucleic acid test, an automated multiplex molecular testing system for detection of C. difficile toxin

The Verigene^®Clostridium difficile nucleic acid test (Verigene^® CDF test) is an automatic and rapid detection system for the genes encoding tcdA, tcdB, binary toxin, and the single nucleotide deletion at base pair 117 in the tcdC based on microarray and PCR amplification. We compared the performance of the Verigene^® CDF test to that of two enzyme immunoassays, C. DIFF QUIK CHEK COMPLETE and X/Pect Toxin A/B, using 118 specimens. We found overall concordance rates of 81.4% and 78.8% between C. DIFF QUIK CHEK COMPLETE and Verigene^® CDF test, and X/Pect Toxin A/B and Verigene^® CDF test. The Verigene^® CDF test showed the highest sensitivity (93.9%) and had a specificity of 96.5%. The sensitivity and specificity were respectively 45.5 and 94.1% for C. DIFF QUIK CHEK COMPLETE and 27.3 and 100.0% for X/Pect Toxin A/B. These results indicated that the Verigene^® CDF test was highly accurate for the detection of C. difficile toxin in fecal specimens and supported its use in daily diagnostic practice.

The emergence of Clostridium difficile infection in Asia: A systematic review and meta-analysis of incidence and impact

Background

Clostridium difficile infection (CDI) is the most common healthcare associated infection and is highly prevalent in Europe and North America. Limited data is available on the prevalence of CDI in Asia. However, secular increases in prevalence of risk factors for CDI suggest that it may be emerging as a major cause of morbidity, highlighting the urgent need for a systematic study of the prevalence of CDI in Asia.

Methods

We systematically searched PubMed/Medline and Embase for publications from Asia between 2000–16 examining prevalence of CDI. A random-effects meta-analysis was performed to calculate the pooled prevalence of CDI in Asia and to identify subgroups and regions at high risk.

Results

Our meta-analysis included 51 studies from throughout Asia including 37,663 patients at risk among whom confirmed CDI was found in 4,343 patients. The pooled proportion of confirmed CDI among all patients with diarrhea was 14.8% with a higher prevalence in East Asia (19.5%), compared with South Asia (10.5%) or the Middle East (11.1%). There were an estimated 5.3 episodes of CDI per 10,000 patient days, similar to rates reported from Europe and North America. Infections due to hypervirulent strains were rare. CDI-related mortality was 8.9%.

Conclusions

In a meta-analysis of 51 studies, we observed similar rates of CDI in Asia in comparison to Europe and North America. Increased awareness and improved surveillance of Clostridium difficile is essential to reduce incidence and morbidity.

Clostridium difficile infection in Thailand

Clostridium difficile is the aetiological agent in ca. 20% of cases of antimicrobial-associated diarrhoea in hospitalised adults. Diseases caused by this organism range from mild diarrhoea to occasional fatal pseudomembranous colitis. The epidemiology of C. difficile infection (CDI) has changed notably in the past decade, following epidemics in the early 2000s of PCR ribotype (RT) 027 infection in North America and Europe, where there was an increase in disease severity and mortality. Another major event has been the emergence of RT 078, initially as the predominant ribotype in production animals in the USA and Europe, and then in humans in Europe. Although there have been numerous investigations of the epidemiology of CDI in North America and Europe, limited studies have been undertaken elsewhere, particularly in Asia. Antimicrobial exposure remains the major risk factor for CDI. Given the high prevalence of indiscriminate and inappropriate use of antimicrobials in Asia, it is conceivable that CDI is relatively common among humans and animals. This review describes the level of knowledge in Thailand regarding C. difficile detection methods, prevalence and antimicrobial susceptibility profile, as well as the clinical features of, treatment options for and outcomes of the disease. In addition, antimicrobial usage in livestock in Thailand will be reviewed. A literature search yielded 18 studies mentioning C. difficile in Thailand, a greater number than from any other Asian country. It is possible that the situation in Thailand in relation to CDI may mirror the situation in other developing Asians countries.

A systematic review for pursuing the presence of antibiotic associated enterocolitis caused by methicillin resistant Staphylococcus aureus

BACKGROUND

Although it has received a degree of notoriety as a cause for antibiotic-associated enterocolitis (AAE), the role of methicillin resistant Staphylococcus aureus (MRSA) in the pathogenesis of this disease remains enigmatic despite a multitude of efforts, and previous studies have failed to conclude whether MRSA can cause AAE. Numerous cases of AAE caused by MRSA have been reported from Japan; however, due to the fact that these reports were written in the Japanese language and a good portion lacked scientific rigor, many of these reports went unnoticed.

METHODS

We conducted a systematic review of pertinent literatures to verify the existence of AAE caused by MRSA. We modified and applied methods in common use today and used a total of 9 criteria to prove the existence of AAE caused by Klebsiella oxytoca. MEDLINE/Pubmed, Excerpta Medica Database (EMBASE), the Cochrane Database of Systematic Reviews, and the Japan Medical Abstract Society database were searched for studies published prior to March 2013.

RESULTS

A total of 1,999 articles were retrieved for evaluation. Forty-five case reports/series and 9 basic studies were reviewed in detail. We successfully identified articles reporting AAE with pathological and microscopic findings supporting MRSA as the etiological agent. We also found comparative studies involving the use of healthy subjects, and studies detecting probable toxins. In addition, we found animal models in which enteritis was induced by introducing MRSA from patients. Although we were unable to identify a single study that encompasses all of the defined criteria, we were able to fulfill all 9 elements of the criteria by collectively analyzing multiple studies.

CONCLUSIONS

AAE caused by MRSA-although likely to be rarer than previous Japanese literatures have suggested-most likely does exist.

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.

Molecular characterization of toxin A-negative, toxin B-positive variant strains of Clostridium difficile isolated in Korea

A(-)B(+)Clostridium difficile strains are prevalent in Korea. We performed pulsed-field gel electrophoresis (PFGE), polymerase chain reaction ribotyping, and toxinotyping in 82 A(-)B(+) clinical isolates in Korea. PFGE showed highest discriminatory capability among the 3 methods. By PFGE, persistence of a clone was found, suggesting this clone has adapted to the hospital environment.

[Rapid-tests detection evaluation of Clostridium difficile toxins and microbiological investigation]

We evaluated two rapid toxin tests for C. difficile combined with stool specimen cultures used from January 2006 to March 2009. Stool specimens numbered 877, 102 among which were from the cases of diagnosed clinical C. difficile-associated diarrhea (CDAD). Rapid toxin A 'Uniquick' detection kits were used until October 2007 and toxin A&B 'TOX A/B' detection kits thereafter. Clinical CDAD was considered the detection gold standard. Uniquick sensitivity, specificity, and positive and negative predictive values were 54.3%, 99.1%, 90.5%, and 93.2% while those for TOX A/B were 46.2%, 97.6%, 65.2%, and 95.0% and for culture 42.2%, 95.5%, 55.1%, and 92.6%. Rapid toxin tests tended to have better sensitivity than culture results although not significantly so, and Uniquick showed significantly better positive predictive value than TOX A/B or culture results. Among clinical CDAD cases, concordance with culture was 24.3% for Uniquick and 53.1% for TOX A/B. For stored strains, 27 were typed toxin A+B+ (48.1%), toxin A-B+ (37.0%) and toxin A-B- (14.8%) with toxin gene detection by PCR. Eight of the 10 toxin A-B+ strains were classified into two cluster by ribotyping, and 7 of those were detected in two hospital wards, indicated the possibility of nosocomial toxin A-B+ strain spread. The rapid toxin test for both toxins A and B should be used if toxin A-B+ predominate. Simultaneous culture testing may be useful for detecting clinical CDAD more accurately, however.

Diagnostic value of repeated enzyme immunoassays in Clostridium difficile infection

OBJECTIVES

There has been a significant increase in the prevalence, severity, and mortality of Clostridium difficile infection (CDI), with an estimated three million new cases per year in the United States. Yet diagnosing CDI remains problematic. The most commonly used test is stool enzyme immunoassay (EIA) detecting toxin A and/or B, but there are no clear guidelines specifying the optimal number of tests to be ordered in the diagnostic workup, although multiple tests are frequently ordered. Thus, we designed a study with the primary objective of evaluating the diagnostic utility of repeat second and third tests of stool EIA detecting both toxins A and B (EIA (A&B)) in cases with negative initial samples, and sought to describe the physicians' patterns of ordering this test in the workup of suspected CDI.

METHODS

A retrospective study was carried out using a database of all stool EIA (A&B) tests ordered for a presumptive diagnosis of CDI. All patients were adults admitted to a major teaching hospital over a three-and-a-half-year period (tests completed within 5 days of ordering the first test were grouped into a single episode, and only the first three samples per episode were analyzed). Age, gender, and results of stool EIA were tabulated. In addition, physicians' ordering patterns and proportion of positive stools relative to the number of tests ordered were also analyzed. A single positive EIA result was interpreted as evidence for the clinical presence of CDI.

RESULTS

A total of 3,712 patients contributed to 5,865 separate diarrhea episodes (total stool EIA (A&B)=9,178), and 1,165 (19.9%) of these episodes were positive for CDI. Of the positive patients, 73.2% were over the age of 65 years and 54.2% of them were females. The most frequent ordering pattern for presumptive CDI was a single stool test (60.1%), followed by two more tests (23.2%). Three tests were still ordered in 16.6% of the cases. Of the 1,165 positive cases, 1,046 (89.8%) were diagnosed in the very first test, 95 (8.2%) in the second, and only 24 (2.0%) in the third test. In 1,934 instances, a second test was ordered after an initial negative result, of which 95 (4.91%) became positive. In 793 episodes, a third test was ordered after two negative samples, of which only 24 (3.03%) became positive.

CONCLUSIONS

This study highlights the low diagnostic yield of repeat stool EIA (A&B) testing. Findings strongly support the utility of limiting the workup of suspected CDI to a single stool test with only one repeat test in cases of high clinical suspicion, and avoiding the routine ordering of multiple stool samples. As Clostridium difficile is becoming an endemic health-care problem resulting in major financial burdens for the US health-care system, clear guidelines specifying the optimal number of stool EIA (A&B) tests to be ordered in the diagnostic workup of suspected CDI must be established to assist physicians in the practice of evidence-based medicine.

Application of multiple-locus variable-number tandem-repeat analysis to determine clonal spread of toxin A-negative Clostridium difficile in a general hospital in Buenos Aires, Argentina

Isolates from patients with Clostridium difficile infection (CDI) usually produce both toxin A (TcdA) and toxin B (TcdB), but an increasing number of reports from Europe and Asia mention infections with TcdA-negative, TcdB-positive (A-/B+) strains, usually characterized as PCR ribotype 017 (type 017). Incidence rates of CDI per 10 000 admissions in a 200-bed Argentinean general hospital were 37, 84, 67, 43, 48 and 42 for the years 2000 to 2005, respectively. The annual percentages of type 017 CDI were 7.7%, 64.6%, 91.4%, 92.0%, 75.0% and 86.4%, respectively. Comparison of 112 017-CDI patients with 41 non-017-CDI patients revealed that 017-CDI patients were more often male (68.8% vs. 46.3%; odds ratio 2.55, 95% confidence interval 1.23-5.50). All type 017 strains tested belonged to toxinotype VIII and had a 1.8-kb deletion in tcdA. In addition, 90% of tested type 017 isolates had high-level resistance to clindamycin and erythromycin, determined by the presence of the ermB gene. Multiple-locus variable-number tandem-repeat analysis (MLVA) was applied to 56 Argentinean isolates and 15 isolates from seven other countries. Country-specific clonal complexes were found in each country. Among 56 Argentinean isolates, four clonal complexes were recognized, accounting for 61% of all isolates. These clonal complexes did not show correlation over time, but seemed to be restricted to specific wards, mainly internal medicine and pulmonology wards. A total of 56% of recurrent infections were caused by a different isolate, despite identification of an identical PCR-ribotype. We conclude that C. difficile type 017 gradually replaced other circulating PCR ribotypes and that MLVA provides detailed insight into nosocomial spread.

Expression of recombinant Clostridium difficile toxin A and B in Bacillus megaterium

Background

Major Clostridium difficile virulence factors are the exotoxins TcdA and TcdB. Due to the large size and poor stability of the proteins, the active recombinant TcdA and TcdB have been difficult to produce.

Results

The toxin genes tcdA and tcdB were amplified by PCR using chromosomal DNA from a toxigenic strain as a template, and cloned into a shuttle vector pHis1522. The sequences of both tcdA and tcdB genes in the vector have been verified by DNA sequencing. The constructs were transformed into B. megaterium protoplasts and the protein expression was controlled under a xylose promoter. The recombinant toxins (rTcdA and rTcdB) were purified from bacterial crude extracts. Approximately 5 – 10 mg of highly purified recombinant toxins were obtained from one liter of bacterial culture. The resulting rTcdA and rTcdB had similar molecular masses to the native toxins, and their biological activities were found to be similar to their native counterparts after an extensive examination.

Conclusion

We have generated the full length and active recombinant TcdA and TcdB in Bacillus megaterium.

Molecular genetic basis of ribotyping

Nearly 2,000 ribotyping-based studies exist, ranging from epidemiology to phylogeny and taxonomy. None precisely reveals the molecular genetic basis, with many incorrectly attributing detected polymorphisms to rRNA gene sequences. Based on in silico genomics, we demonstrate that ribotype polymorphisms result from sequence variability in neutral housekeeping genes flanking rRNA operons, with rRNA gene sequences serving solely as conserved, flank-linked tags. We also reveal that from such an informatics perspective, it is readily feasible a priori to design an interpretable ribotyping scheme for a genomically sequenced microbial species, and we discuss limitations to the basic restriction fragment length polymorphism-based method as well as alternate PCR ribotyping-based schemes.