Clostridium difficile infection of the gut

Spatial and Temporal Analysis ofClostridium difficileInfection in Patients at a Pediatric Hospital in California

Objective:

To examine the usefulness of temporal and spatial analysis in identifying nosocomial transmission ofClostridium difficileamong pediatric patients hospitalized on four wards at The Children's Hospital of Central California from September 8,1998, to January 16,1999.

Design:

Stool specimens obtained from the clinical microbiology laboratory during the study period were tested by culture and latex agglutination forC. difficile.Polymerase chain reaction was used to identify toxin genes. Isolates obtained were mapped to a grid for each ward and were analyzed using the Knox test. Results were compared with DNA fingerprints generated by arbitrarily primed polymerase chain reaction.

Results:

Total occupancy of these 4 wards was 438 during the study period. Stool specimens were available for 256 (58%) of these patients, yielding 67C. difficileisolates and generating 2,211 case pairs for analysis by the Knox test. After stratification by toxin status, 5 clustered pairs of toxigenic isolates were identified on 1 of the wards by this method. Fingerprint analysis identified 4 clusters with indistinguishable banding patterns on 2 of the 4 wards. Two of the identified clusters were toxigenic and 2 were nontoxigenic. None of these clusters corresponded to clusters identified by the Knox test.

Conclusions:

The Knox test is an ineffective method for identifying cases resulting from nosocomial transmission ofC. difficilein a pediatric setting due to the persistence ofC. difficilespores and the unique environment of a pediatric hospital. Molecular analysis remains the most effective method.

Clostridium difficile modulates host innate immunity via toxin-independent and dependent mechanism(s)

Clostridium difficile infection (CDI) is the leading cause of hospital and community-acquired antibiotic-associated diarrhoea and currently represents a significant health burden. Although the role and contribution of C. difficile toxins to disease pathogenesis is being increasingly understood, at present other facets of C. difficile-host interactions, in particular, bacterial-driven effects on host immunity remain less studied. Using an ex-vivo model of infection, we report that the human gastrointestinal mucosa elicits a rapid and significant cytokine response to C. difficile. Marked increase in IFN-γ with modest increase in IL-22 and IL-17A was noted. Significant increase in IL-8 suggested potential for neutrophil influx while presence of IL-12, IL-23, IL-1β and IL-6 was indicative of a cytokine milieu that may modulate subsequent T cell immunity. Majority of C. difficile-driven effects on murine bone-marrow-derived dendritic cell (BMDC) activation were toxin-independent; the toxins were however responsible for BMDC inflammasome activation. In contrast, human monocyte-derived DCs (mDCs) released IL-1β even in the absence of toxins suggesting host-specific mediation. Infected DC-T cell crosstalk revealed the ability of R20291 and 630 WT strains to elicit a differential DC IL-12 family cytokine milieu which culminated in significantly greater Th1 immunity in response to R20291. Interestingly, both strains induced a similar Th17 response. Elicitation of mucosal IFN-γ/IL-17A and Th1/Th17 immunity to C. difficile indicates a central role for this dual cytokine axis in establishing antimicrobial immunity to CDI.

Clostridium difficile MazF toxin exhibits selective, not global, mRNA cleavage

Clostridium difficile is an important, emerging nosocomial pathogen. The transition from harmless colonization to disease is typically preceded by antimicrobial therapy, which alters the balance of the intestinal flora, enabling C. difficile to proliferate in the colon. One of the most perplexing aspects of the C. difficile infectious cycle is its ability to survive antimicrobial therapy and transition from inert colonization to active infection. Toxin-antitoxin (TA) systems have been implicated in facilitating persistence after antibiotic treatment. We identified only one TA system in C. difficile strain 630 (epidemic type X), designated MazE-cd and MazF-cd, a counterpart of the well-characterized Escherichia coli MazEF TA system. This E. coli MazF toxin cleaves mRNA at ACA sequences, leading to global mRNA degradation, growth arrest, and death. Likewise, MazF-cd expression in E. coli or Clostridium perfringens resulted in growth arrest. Primer extension analysis revealed that MazF-cd cleaved RNA at the five-base consensus sequence UACAU, suggesting that the mRNAs susceptible to cleavage comprise a subset of total mRNAs. In agreement, we observed differential cleavage of several mRNAs by MazF-cd in vivo, revealing a direct correlation between the number of cleavage recognition sites within a given transcript and its susceptibility to degradation by MazF-cd. Interestingly, upon detailed statistical analyses of the C. difficile transcriptome, the major C. difficile virulence factor toxin B (TcdB) and CwpV, a cell wall protein involved in aggregation, were predicted to be significantly resistant to MazF-cd cleavage.

Clostridium difficile infection: epidemiology and control measurements

Clostridium difficile (C. difficile) is the most commonly recognized cause of nosocomial infection and antibiotic-associated diarrhea in healthcare settings. C. difficile infection (CDI) can result in pseudomembranous colitis. The diagnosis of CDI should be based on a combination of clinical and laboratory findings. The majority of CDIs are acquired from external sources, and healthcare facilities are the main sources of transmission. Rational use of antibiotics is the most effective method to prevent CDI. Effective control measurements for nosocomial infection should be emphasized in healthcare settings to prevent the transmission of CDI. Limited data have shown that probiotics may be effective for the prevention of CDI.

Effect of sub-MIC concentrations of metronidazole, vancomycin, clindamycin and linezolid on toxin gene transcription and production in Clostridium difficile

Clostridium difficileis the major cause of hospital-acquired infectious diarrhoea. Several antimicrobials are known to induce and promoteC. difficile-associated diarrhoea (CDAD). The impact of metronidazole (MTR), vancomycin (VAN), clindamycin (CLI) and linezolid (LZD) on growth, toxin gene transcription and toxin production inC. difficilewas investigated. FourC. difficilestrains were grown with and without sub-MIC concentrations of MTR, VAN, CLI and LZD (0.5× MIC) and growth was measured by colony counts. Toxin production was detected using ELISA (for toxin A) and a cytotoxicity assay (for toxin B) in culture supernatants and also in sonicated cells. Real-time PCR was used to measure transcription of the toxin A and B genes. The aim of this work was to combine analysis of toxin A and B production by ELISA or cell culture assay with transcriptomic analysis. The four strains showed similar growth and different levels of toxin production in the absence of antibiotics. An antibiotic-free control showed toxin production at a late stage when the plateau phase of bacterial growth was reached, whereas antibiotic-exposed strains showed earlier toxin production. All of the antibiotics used except CLI increased the transcription rate of toxin genes. The findings of this study show that sub-MIC concentrations of antibiotics can cause changes in gene transcription of the major virulence factors ofC. difficile. This study describes a new method for transcriptomic analysis of toxin genes inC. difficile.

Efficacy and safety of Saccharomyces boulardii in prevention of antibiotic-associated diarrhoea due to Helicobacterpylori eradication

BACKGROUND AND AIM

Antibiotic-associated diarrhoea may develop during or following Helicobacter pylori eradication. We aimed to evaluate the efficacy and safety of Saccharomyces boulardii in preventing antibiotic-associated diarrhoea in patients receiving antibiotics for H. pylori eradication.

METHODS

In a multicentre prospective clinical trial, patients with peptic ulcer disease or non-ulcer dyspepsia were enrolled to receive clarithromycin, amoxicillin and omeprazole for H. pylori eradication for 14 days. These patients were then randomized to receive either S. boulardii 500 mg twice daily (treatment group) or no treatment (control group). The primary outcome measure was the development of diarrhoea during (treatment period) or within 4 weeks after treatment (follow-up period).

RESULTS

Of the 389 patients that were enrolled, 376 completed the study. Within the treatment period, diarrhoea developed in 5.9% of patients in the treatment group and in 11.5% of patients in the control group (P = 0.049); and in the follow-up period, diarrhoea developed in 1.0% of patients in the treatment group and in 3.8% of patients in the control group (P = 0.09). Overall diarrhoea rates throughout the whole study period were 6.9% in the treatment group and 15.6% in the control group (P = 0.007). No significant difference was observed between the treatment and control groups in terms of adverse events.

CONCLUSION

S. boulardii is an effective and safe treatment for prevention of antibiotic-associated diarrhoea when given concomitantly to patients receiving H. pylori eradication.

Effects of piperacillin/tazobactam on Clostridium difficile growth and toxin production in a human gut model

OBJECTIVES

Clostridium difficile infection (CDI) is a major cause of morbidity in the nosocomial environment. Antimicrobial agents such as the third-generation cephalosporins, lincosamides and aminopenicillins are well known for their propensity to induce CDI, but the definitive reasons why remain to be elucidated. Despite their broad spectrum of activity against both aerobic and anaerobic bacteria, the ureidopenicillins remain a class of antimicrobials infrequently associated with the development of CDI.

METHODS

We used a triple-stage chemostat model that simulates the human gut to study the effects of the ureidopenicillin/beta-lactamase inhibitor combination piperacillin/tazobactam on gut bacterial populations and C. difficile.

RESULTS

Piperacillin/tazobactam rapidly reduced all enumerated gut bacterial populations (including bacteroides, bifidobacteria and lactobacilli) below the limits of detection by the end of the piperacillin/tazobactam instillation period. Despite such widespread disruption of gut bacterial populations, C. difficile populations remained principally as spores, with no sustained proliferation or high-level cytotoxin production observed.

CONCLUSIONS

Factors other than reduced colonization resistance must be responsible for determining whether CDI develops following antimicrobial administration. We believe the gut model is a promising approach for the study of C. difficile pathogenesis reflecting in vivo events likely to occur in CDI.

Clostridium difficile: a survey of fecal carriage in cats in a veterinary medical teaching hospital

Fecal samples collected from 245 cats over a 6-month period were analyzed for the presence of Clostridium difficile. After culture on selective media, isolates were identified by a latex agglutination test, and the presence of toxin A and toxin B gene sequences was determined by polymerase chain reaction. Clostridium difficile was isolated from 23 (9.4%) of the cats, and 34.8% of that group were colonized with toxigenic strains. All of the cats colonized with toxigenic C. difficile had > or = 1 of the risk factors (antibiotic use, antineoplastic therapy, immunosuppressive virus infection) associated with C. difficile infection in humans. Clostridium difficile was not found in any of the cats from a clinically healthy outpatient group of cats examined from the same hospital nor in cats from a specific-pathogen-free research colony on the same campus tested during the same time period. The data obtained in this study confirm the presence of C. difficile in cats at a veterinary teaching hospital. DNA fingerprinting analysis of these isolates allowed separation of the strains into 5 groups. Type 4 strain found in 7 cats was also recovered from the floor drain in the same hospital, suggesting a possible source of infection. Whether the organism is of clinical significance in diarrheal diseases of cats remains to be determined.

Clostridium difficile-associated diarrhea and colitis: clinical manifestations, diagnosis, and treatment

PURPOSE

This review examines the pathogenesis, clinical manifestations, diagnosis, and current medical and operative strategies in the treatment of Clostridium difficile diarrhea and colitis. Prevention and future avenues of research are also investigated.

METHODS

A review of the literature was conducted with the use of MEDLINE.

RESULTS

C. difficile is a gram-positive, spore-forming bacterium capable of causing toxigenic colitis in susceptible patients, usually those receiving antibiotics. Overgrowth of toxigenic strains may result in a spectrum of disease, including becoming an asymptomatic carrier, diarrhea, self-limited colitis, fulminant colitis, and toxic megacolon. Diagnosis requires a high index of suspicion and depends on clinical data, laboratory stool studies (enzyme-linked immunoabsorbent assay and cytotoxin test), and endoscopy in selected cases. Protocols for treatment of primary and relapsing infections are provided in algorithm format. Discontinuation of antibiotics may be enough to resolve symptoms. Medical management with oral metronidazole or vancomycin is the first-line therapy for those with symptomatic colitis. Teicoplanin, Saccharomyces spp. and Lactobacillus spp., and intravenous IgG antitoxin are reserved for more recalcitrant cases. Refractory or relapsing infections may require vancomycin given orally or other newer modalities. Fulminant colitis and toxic megacolon warrant subtotal colectomy. Cost, in terms of extended hospital stay, medical and surgical management, and, in some cases, ward closure, is thought to be formidable. Review of perioperative antibiotic policies and analysis of hospital formularies may contribute to prevention and decreased costs.

CONCLUSION

C. difficile diarrhea and colitis is a nosocomial infection that may result in significant morbidity, mortality, and medical costs. Standard laboratory studies and endoscopic evaluation assist in the diagnosis of clinically suspicious cases. Appropriate perioperative antibiotic dosing, narrowing the antibiotic spectrum when treating infections, and discontinuing antibiotics at appropriate intervals prevent toxic sequelae.

Evaluation of a new enzyme immunoassay for Clostridium difficile toxin A

AIM

To evaluate a new enzyme immunoassay (EIA) method for detection of Clostridium difficile toxin by comparing it to cytotoxicity assay. To investigate the nature of false negative and false positive EIA results by evaluating clinical and therapeutic parameters.

METHODS

737 consecutive diarrhoeal specimens collected from patients clinically suspected of having C difficile colitis were tested for the presence of C difficile toxin by EIA for toxin A and by cytotoxicity assay. Clinical data were evaluated in all cases positive by either method.

RESULTS

With the cytotoxicity assay as a gold standard, the specificity of EIA for toxin detection was 99.3% and the sensitivity was 62.2%. No false negative EIA specimens were obtained from patients already being treated for C difficile colitis. Among patients with cytotoxicity positive specimens, those with EIA positive samples had no clinical features distinguishing them from patients with EIA negative samples.

CONCLUSIONS

Although specific, the new EIA method directed against toxin A lacks sensitivity compared to cytotoxicity. False negative EIA tests are not associated with concurrent treatment for C difficile colitis nor with any specific clinical features examined in our study.