Clostridium difficile infections in China

Clostridium difficile (C. difficile) infection has become one of the major hospital-associated infections in Western countries in the last two decades. However, there is limited information on the status of C. difficile infection in Chinese healthcare settings. Given the large and increasing elderly population and the well-recognized problem of over-prescribing of broad spectrum antibiotics in China, it is critical to understand the epidemiology and potential risk factors that may contribute to C. difficile infection in China. A literature review of available published studies, including those in Chinese language-based journals, was conducted. A review of the currently available literature suggested the presence of C. difficile infections in China, but also suggested that these infections were not particularly endemic. This finding should lead to better designed and greatly expanded studies to provide a more reliable epidemiologically-based conclusion on the actual status of C. difficile infection in China, including the identification of any associated risk factors. Such information is ultimately valuable to develop appropriate strategies to prevent C. difficile infection and the vast negative impact of such infections in China and other developing countries.     

Epidemiology and clinical characteristics of Clostridium difficile infection in a Korean tertiary hospital

In order to investigate the incidence, clinical and microbiologic characteristics of Clostridium difficile infection (CDI) in Korea, a prospective observational study was performed. From September 2008 through January 2010, all patients whose stool was tested for toxin assay A&B and/or C. difficile culture were studied for clinical characteristics. Toxin types of the isolates from stool were tested. The mean incidence of CDI per 100,000 patient-days was 71.6 by month (range, 52.5-114.0), and the ratio of CDI to antibiotic-associated diarrhea was 0.23. Among 200 CDI patients, 37.5% (75/200) was severe CDI based on severity score. Clinical outcome of 189 CDI was as followed; 25.9% (49/189) improved without treatment, 84.3% (118/140) achieved clinical cure and attributed mortality was 0.7% (1/140) with the treatment. Recurrence rate was 21.4% (30/140) and cure without recurrence was 66.4% (93/140). The most common type of toxin was toxin A-positive/toxin B-positive strain (77.5%), toxin A-negative/toxin B-positive strains or binary toxin-producing strains comprised 15.4% or 7.1%, respectively. In conclusion, the incidence of CDI in Korea is a little higher than other reports during the non-epidemic setting. We expect that the change of epidemiology and clinical severity in CDI can be evaluated based on these results.     

Evaluation of a Chromogenic Culture Medium for the Detection of Clostridium difficile

Purpose

Clostridium difficile (C. difficile) is an important cause of nosocomial diarrhea. Diagnostic methods for detection of C. difficile infection (CDI) are shifting to molecular techniques, which are faster and more sensitive than conventional methods. Although recent advances in these methods have been made in terms of their cost-benefit, ease of use, and turnaround time, anaerobic culture remains an important method for detection of CDI.

Materials and Methods

In efforts to evaluate a novel chromogenic medium for the detection of C. difficile (chromID CD agar), 289 fecal specimens were analyzed using two other culture media of blood agar and cycloserine-cefoxitin-fructose-egg yolk agar while enzyme immunosorbent assay and polymerase chain reaction-based assay were used for toxin detection.

Results

ChromID showed the highest detection rate among the three culture media. Both positive rate and sensitivity were higher from chromID than other culture media. ChromID was better at detecting toxin producing C. difficile at 24 h and showed the highest detection rate at both 24 h and 48 h.

Conclusion

Simultaneous use of toxin assay and anaerobic culture has been considered as the most accurate and sensitive diagnostic approach of CDI. Utilization of a more rapid and sensitive chromogenic medium will aid in the dianogsis of CDI.     

Diagnostic accuracy of loop-mediated isothermal amplification in detection of Clostridium difficile in stool samples: a meta-analysis

Introduction

Clostridium difficile infection (CDI) remains a diagnostic challenge for clinicians. More recently, loop-mediated isothermal amplification (LAMP) has become readily available for the diagnosis of CDI, and many studies have investigated the usefulness of LAMP for rapid and accurate diagnosis of CDI. However, the overall diagnostic accuracy of LAMP for CDI remains unclear. In this meta-analysis, our aim was to establish the overall diagnostic accuracy of LAMP in detection of Clostridium difficile (CD) in stool samples.

Material and methods

A search was done in PubMed, MEDLINE, EMBASE and Cochrane Library databases up to February 2014 to identify published studies that evaluated the diagnostic role of LAMP for CD. Methodological quality was assessed according to the quality assessment for studies of diagnostic accuracy (QUADAS) instrument. The sensitivities (SEN), specificities (SPE), positive likelihood ratio (PLR), negative likelihood ratio (NLR) and diagnostic odds ratio (DOR) were pooled statistically using random effects models. Statistical analysis was performed by employing Meta-Disc 1.4 software. Summary receiver operating characteristic (SROC) curves were used to summarize overall test performance. Funnel plots were used to test the potential publication bias.

Result

A total of 9 studies met inclusion criteria for the present meta-analysis. The pooled SEN and SPE for diagnosing CD were 0.93 (95% CI: 0.91–0.95) and 0.98 (95% CI: 0.98–0.99), respectively. The PLR was 47.72 (95% CI: 15.10–150.82), NLR was 0.07 (95% CI: 0.04–0.14) and DOR was 745.19 (95% CI: 229.30−2421.72). The area under the ROC was 0.98. Meta-regression indicated that the total number of samples was a source of heterogeneity for LAMP in detection of CD. The funnel plots suggested no publication bias.

Conclusions

The LAMP meets the minimum desirable characteristics of a diagnostic test of SEN, SPE and other measures of accuracy in the diagnosis of CD, and it is suitable as a rapid, effective and reliable stand-alone diagnostic test for diagnosis of CDI, potentially decreasing morbidity and nosocomial spread of CD.     

Risk factors for recurrence of Clostridium difficile infection: effect of vancomycin-resistant enterococci colonization

Recurrent Clostridium difficile infection (CDI) is one of the most difficult problems in healthcare infection control. We evaluated the risk factors associated with recurrence in patients with CDI. A retrospective cohort study of 84 patients with CDI from December 2008 through October 2010 was performed at Pusan National University Yangsan Hospital. Recurrence occurred in 13.1% (11/84) of the cases and in-hospital mortality rate was 7.1% (6/84). Stool colonization with vancomycin-resistant enterococci (VRE) (P = 0.006), exposure to more than 3 antibiotics (P = 0.009), low hemoglobin levels (P = 0.025) and continued use of previous antibiotics (P = 0.05) were found to be more frequent in the recurrent group. Multivariate analysis indicated that, stool VRE colonization was independently associated with CDI recurrence (odds ratio, 14.519; 95% confidence interval, 1.157-182.229; P = 0.038). This result suggests that stool VRE colonization is a significant risk factor for CDI recurrence.     

The First Case of Antibiotic-associated Colitis by Clostridium difficile PCR Ribotype 027 in Korea

Clostridium difficile (C. difficile) is a common causative agent of pseudomembranous colitis (PMC). C. difficile-associated diarrhea (CDAD) ranges from mild diarrhea to life threatening PMC. Recently, a highly virulent strain of C. difficile polymerase chain reaction ribotype 027 was found in North America, Europe, and Japan. A 52-yr-old woman with anti-tuberculosis medication and neurogenic bladder due to traffic accident experienced five episodes of C. difficile PMC after taking antibiotics for pneumonia along with septic shock and acute renal failure. She was readmitted to the intensive care unit and treated with oral vancomycin with refractory of oral metronidazole, inotropics and probiotics for over 60 days. C. difficile isolated both at the first and the last admission was identified as C. difficile ribotype 027 by ribotyping, toxinotyping, and tcdC gene sequencing, which turned out the same pathogen as the epidemic hypervirulent B1/NAP1 strain. This is the first case of C. difficile PCR ribotype 027 in Korea. After discharge, she was maintained on probiotics and rifaximin for 3 weeks. She had no relapse for 6 months.     

Release of TcdA and TcdB from Clostridium difficile cdi 630 is not affected by functional inactivation of the tcdE gene

The small open reading frame tcdE is located between the genes tcdA and tcdB which encode toxin A (TcdA) and B (TcdB), respectively, within the pathogenicity locus of Clostridium difficile. Sequence and structure similarities to bacteriophage-encoded holins have led to the assumption that TcdE mediates the release of the toxins from C. difficile into the extracellular environment. A TcdE-deficient C. difficile 630 strain was generated by insertional inactivation of the tcdE gene. Data revealed that TcdE does not regulate or affect growth or sporogenesis. TcdE-deficiency was accompanied by a moderately increased accumulation of TcdA and TcdB prior to sporulation in this microorganism. Interestingly, this observation did not correlate with a delayed or inhibited toxin release: inactivation of TcdE neither significantly altered kinetics of release nor the absolute level of secreted TcdA and TcdB, indicating that TcdE does not account for the pathogenicity of C. difficile strain 630. Furthermore, mass spectrometry analysis could not reveal differences in the secretome of wild type and TcdE-deficient C. difficile, indicating that TcdE did not function as a secretion system for protein release. TcdE was expressed as a 19 kDa protein in C. difficile, whereas TcdE expressed in Escherichia coli appeared as a 19 and 16 kDa protein. Expression of the short 16 kDa TcdE correlated with bacterial cell death. We conclude that TcdE does not exhibit pore-forming function in C. difficile since in these cells only the non-lytic full length 19 kDa protein is expressed.     

A case of pseudomembranous colitis after voriconazole therapy

This is a case report on a 35-year-old man with acute myelogenous leukemia who presented fever and intermittent mucoid loose stool to the emergency center. He had been taking voriconazole for invasive pulmonary aspergillosis. The flexible sigmoidoscopy was consistent with the diagnosis of pseudomembranous colitis.     

ABCB1 polymorphisms associated with osteonecrosis of the femeral head

Aims: This case-control study was conducted to investigate the relation of ATP-binding cassette subfamily B member 1 (ABCB1) C1236T and C3435T polymorphisms and non-traumatic osteonecrosis of the femeral head (ONFH). Methods: We gathered 113 ONFH patients and 116 controls in the study. The polymorphisms of ABCB1 were genotyped by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technology. Odds ratio (OR) with 95% confidence interval (CI) were adopted to analyze the correlation between ABCB1 polymorphisms and ONFH. Results: In the study, we found that the frequency of C3435T TT genotype was much lower in case group, compared with that of controls (17.7% vs. 23.3%). Moreover, OR and 95% CI values indicated that C3435T TT genotype served as a protective factor for ONFH (OR=0.34, 95% CI=0.15-0.75). Meanwhile, the risk for the T allele carriers was much lower than C allele (OR=0.60, 95% CI=0.42-0.87). However, C1236T polymorphism showed no significant effects on the pathogenesis of ONFH. In the haplotype analysis, T-T haplotype appeared to be an inhibitor for ONFH (OR=0.45, 95% CI=0.23-0.87). Conclusions: Based on the results, ABCB1 polymorphisms were associated with the risk for ONFH.     

Antecedent use of fluoroquinolones is associated with resistance to moxifloxacin in Clostridium difficile

Objective   Moxifloxacin is characterized by high activity against Gram-positive cocci and some Gram-positive and -negative anaerobes, including Clostridium difficile . This study investigates the role of prior quinolone use in relation to patterns of susceptibility of C. difficile to moxifloxacin.
Methods   Sixty-three clinical isolates of C. difficile were investigated for toxigenicity, susceptibility to moxifloxacin, and mutations in the DNA gyrase gene. The medical histories for 50 of these patients were available and used to identify previous fluoroquinolone use.
Results   Thirty-three (52.4%) strains showed resistance to moxifloxacin (MICs ≥ 16 mg/L). All moxifloxacin-resistant strains harbored a mutation at amino acid codon Ser-83 of gyrA . Forty-five isolates (71.4%) were toxigenic; all moxifloxacin-resistant strains were in this group. Resistance to moxifloxacin was associated with prior use of fluoroquinolones ( P -value 0.009, chi-square).
Conclusions   Although the use of moxifloxacin to treat C. difficile -associated diarrhea is not likely to be common, these data show a relationship between antecedent fluoroquinolone use and resistance to moxifloxacin in C. difficile isolates, and raise questions regarding selection pressure for resistance placed on colonizing bacteria exposed to fluoroquinolones. Mutations in gyrA are involved in moxifloxacin resistance.     

CIAPIN1 gene silencing enhances chemosensitivity in a drug-resistant animal model in vivo

Overexpression of cytokine-induced apoptosis inhibitor 1 (CIAPIN1) contributes to multidrug resistance (MDR) in breast cancer. This study aimed to evaluate the potential of CIAPIN1 gene silencing by RNA interference (RNAi) as a treatment for drug-resistant breast cancer and to investigate the effect of CIAPIN1 on the drug resistance of breast cancer in vivo. We used lentivirus-vector-based RNAi to knock down CIAPIN1 in nude mice bearing MDR breast cancer tumors and found that lentivirus-vector-mediated silencing of CIAPIN1 could efficiently and significantly inhibit tumor growth when combined with chemotherapy in vivo. Furthermore, Western blot analysis showed that both CIAPIN1 and P-glycoprotein expression were efficiently downregulated, and P53 was upregulated, after RNAi. Therefore, we concluded that lentivirus-vector-mediated RNAi targeting of CIAPIN1 is a potential approach to reverse MDR of breast cancer. In addition, CIAPIN1 may participate in MDR of breast cancer by regulating P-glycoprotein and P53 expression.     

MOK overexpression is associated with promoter hypomethylation in patients with acute myeloid leukemia

Overexpression of MAPK/MAK/MRK overlapping kinase (MOK) has been found in various tumors. However, the mechanism underlying MOK upregulation remains unclear. A CpG island was identified in MOK promoter. In this study, we evaluated the expression and methylation status of MOK gene in acute myeloid leukemia (AML). Hypomethylation of MOK promoter was detected in 31.0% (45/145) of AML patients. The degree of MOK hypomethylation was significantly correlated with MOK expression in AML patients. MOK-hypomethylated patients had a trend towards lower WBCs. Receiver operating characteristic curve (ROC) analysis showed a good performance in distinguishing AML patients from controls with an area under the ROC curve (AUC) of 0.820 (P < 0.001). In summary, our results suggest MOK promoter hypomethylation is a common event and contributes to MOK overexpression in AML.     

Molecular epidemiology and resistance profiles of Clostridium difficile in a tertiary care hospital in Spain

Epidemiological surveillance of Clostridium difficile infection has gained importance in recent years as a result of the rapid spread of epidemic strains, including hypervirulent strains and strains with reduced susceptibility to antimicrobials. The molecular epidemiology and antimicrobial susceptibility of C. difficile in the reference hospital of the Balearic Islands (Spain) is reported in this study. One hundred isolates of toxigenic C. difficile from different patients were selected using rapid dual EIA screening test. All isolates were characterized through toxin profile, PCR ribotyping and, in addition, multi-locus sequence typing (MLST) was performed on fifty selected strains. MICs to metronidazole, vancomycin, erythromycin and moxifloxacin were also determined. A total of 43 different ribotypes were distinguished, with higher prevalence of ribotype 014 (34%). Twenty one per cent of the isolates expressed binary toxin and it is noteworthy that 62% of these were identified as the hypervirulent ribotype 078, the second most prevalent ribotype found in our hospital (13%). A total of 20 different sequence types (STs) were found, including a new described allele and ST. MLST data showed a clear concordance between some ribotypes and STs, mainly represented by ribotype 014/ST-2, ribotype 078/ST-11 and ribotype 001/ST-3. Phylogenetic analysis also revealed that most of the isolates were genetically related, forming a large clonal complex. Finally, ribotypes 078 (ST-11) and 001 (ST-3) were associated with higher resistance to erythromycin and to erythromycin and moxifloxacin, respectively. All these data suggest that the combination of ribotyping and MLST is a good tool for the surveillance of the changing epidemiology of C. difficile. A wide dissemination of clones has been observed in our setting, ribotype 014 (ST-2) being the most prevalent followed by the hypervirulent ribotype 078 (ST-11) and ribotype 001 (ST-3), their spread in our setting probably influenced by their higher resistance.     

The emergence of ‘hypervirulence’ in Clostridium difficile

The impact of Clostridium difficile-associated disease (CDAD) in healthcare settings throughout the developed world is considerable in terms of mortality, morbidity, and disease management. The incidence of CDAD has risen dramatically since the turn of this century, concomitant with the emergence of so-called hypervirulent strains which are thought to cause a more severe disease, higher relapse rates, and increased mortality. Pre-eminent amongst hypervirulent strains are those belonging to ribotype 027, which were first reported in Canada in 2003 and shortly thereafter in the UK. Since its arrival in Europe, it has spread rapidly and has now been reported in 16 member states and Switzerland. The physiological factors responsible for the rapid emergence of hypervirulent C. difficile strains remain unclear. It is known that they produce a binary toxin (CDT) in addition to toxins A and B, that they are resistant to fluoroquinolones due to mutations in gyrA, and that they are resistant to erythromycin. Representative strains have been suggested to produce more toxin A and B in the ‘laboratory flask’ (most likely due to a frameshift mutation in the repressor gene tcdC), to be more prolific in terms of spore formation, and also exhibit increased adherence to human intestinal epithelial cells due to altered surface proteins. However, the contribution of these and other as yet unidentified factors to the rapid spread of certain C. difficile variants (e.g., ribotypes 027 and 078) remains unclear at present. The advent of ClosTron technology means that it is now possible to construct genetically stable isogenic mutants of C. difficile and carry out reverse genetic studies to elucidate the role of specific gene loci in causing disease. The identification of virulence factors using this approach should help lead to the rational development of therapeutic countermeasures against CDAD.     

Interleukin‐23 (IL‐23), independent of IL‐17 and IL‐22, drives neutrophil recruitment and innate inflammation during Clostridium difficile colitis in mice

Our objective was to determine the role of the inflammatory cytokine interleukin‐23 (IL‐23) in promoting neutrophil recruitment, inflammatory cytokine expression and intestinal histopathology in response to Clostridium difficile infection. Wild‐type (WT) and p19^−/− (IL‐23KO) mice were pre‐treated with cefoperazone in their drinking water for 5 days, and after a 2‐day recovery period were challenged with spores from C. difficile strain VPI 10463. Interleukin‐23 deficiency was associated with significant defects in both the recruitment of CD11b^High Ly6G^High neutrophils to the colon and the expression of neutrophil chemoattractants and stabilization factors including Cxcl1, Cxcl2, Ccl3 and Csf3 within the colonic mucosa as compared with WT animals. Furthermore, the expression of inflammatory cytokines including Il33, Tnf and Il6 was significantly reduced in IL‐23‐deficient animals. There was also a trend towards less severe colonic histopathology in the absence of IL‐23. The induction of Il17a and Il22 was also significantly abrogated in IL‐23KO mice. Inflammatory cytokine expression and neutrophilic inflammation were not reduced in IL‐17a‐deficient mice or in mice treated with anti‐IL‐22 depleting monoclonal antibody. However, induction of RegIIIg was significantly reduced in animals treated with anti‐IL‐22 antibody. Taken together, these data indicate that IL‐23, but not IL‐17a or IL‐22, promotes neutrophil recruitment and inflammatory cytokine and chemokine expression in the colon in response to C. difficile infection.     

PIK3CA polymorphisms associated with susceptibility to hepatocellular carcinoma

Purpose: Our study was carried out to explore the relationship of PIK3CA rs17849071 and rs17849079 polymorphisms with the susceptibility to hepatocellular carcinoma (HCC) in Chinese Han population. Methods: 150 HCC patients and 152 healthy individuals were recruited in the case and control groups respectively. The genotypes of PIK3CA rs17849071 and rs17849079 polymorphisms were detected with polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. The linkage disequilibrium and haplotypes were analyzed with Haploview software. Differences in frequencies of genotypes, alleles, and haplotypes between the case and control groups were checked with χ² test. The controls were matched with the cases in age and gender. The relative risk of HCC was represented by odds ratio (OR) and 95% confidence interval (95% CI). Results: Significant difference in frequencies of GG genotype and G allele in PIK3CA rs17849071 polymorphism existed between the two groups (P=0.040; P=0.028), indicating that rs17849071 was closely related to the increased risk of HCC (OR=2.919, 95% CI=1.007-8.460; OR=1.642, 95% CI=1.051-2.564). Furthermore, TT genotype also significantly increased the susceptibility to HCC (OR=3.438, 95% CI=1.050-11.250) and so was T allele (OR=1.521, 95% CI=1.052-2.199). The haplotype analysisshowed that G-T haplotypes were higher in cases than that of controls (P=0.030), which suggested that G-T might be a susceptible haplotype to HCC. Conclusions: The PIK3CA rs17849071 and rs17849079 polymorphisms may increase the risk of HCC either independently or synergistically.     

Transmission of Clostridium difficile spores in isolation room environments and through hospital beds

The aim of this study was to determine the dissemination of Clostridium difficile (CD) spores in a hospital setting where the potassium monopersulfate‐based disinfectant Virkon^TM was used for cleaning. In the initial part of the study, we sampled 16 areas of frequent patient contact in 10 patient rooms where a patient with CD infection (CDI) had been accommodated. In the second part of the study, we obtained samples from 10 patient beds after discharge of CDI patients, both before and after the beds were cleaned. In the first part, CDspores were isolated in only 30% of the rooms. In the second part, which focused on transmission to hospital beds, C. difficile was found in four of 10 beds either before or after cleaning. In conclusion, in both parts of the study, we demonstrated a moderate spread of CD spores to the environment despite routine cleaning procedures involving Virkon^TM.     

Evidence for low risk of Clostridium difficile infection associated with tigecycline

Broad-spectrum antibiotics are often associated with a relatively high risk of Clostridium difficile infection (CDI). However, exceptions to this rule, e.g., piperacillin-tazobactam, show that marked inhibition of gut flora is not synonymous with CDI risk. Tigecycline has marked broad-spectrum activity that includes Gram-positive and Gram-negative facultative and obligate anaerobes. Antibiotic susceptibility, gut model and clinical trial data suggest that tigecycline is associated with a relatively low risk of CDI. Further clinical data should be obtained to confirm the results of these initial studies.