Clostridium difficile toxins and enterococcal translocation in vivo and in vitro

Detection of coexisting toxigenic Clostridium difficile and nontyphoidal Salmonella in a healthcare worker with diarrhea: A therapeutic dilemma

Introduction:

Clostridium difficile infection (CDI) and nontyphoidal Salmonella infection (NSI) have similar clinical manifestations and are seldom seen simultaneously. The decision-making in terms of antibiotic therapy becomes difficult when both the pathogens are isolated from the same patient.

Case Presentation:

We describe a case of Clostridium difficile (CD) enterocolitis in a healthcare provider who concomitantly tested positive for nontyphoidal Salmonella.

Discussion:

To the best of our knowledge after extensive literature review (English), this is only the fourth report highlighting this association.

Conclusion:

Although Salmonella is not a risk factor for CDI, it can cause intestinal inflammation and alteration in the intestinal flora. When two pathogens are isolated from the same patient, it is tempting to treat both with antibiotics as highlighted. When it involves healthcare workers, there is no difference in guidelines and should not be prescribed antibiotics with intent of reducing secondary transmission.

Human foreskin fibroblasts: from waste bag to important biomedical applications

Circumcision is one of the most performed surgical procedures worldwide, and it is estimated that one in three men worldwide is circumcised, which makes the preputial skin removed after surgery an abundant material for possible applications. In particular, it is possible efficiently to isolate the cells of the foreskin, with fibroblasts being the most abundant cells of the dermis and the most used in biomedical research. This work aimed to review the knowledge and obtain a broad view of the main applications of human foreskin fibroblast cell culture. A literature search was conducted, including clinical trials, preclinical basic research studies, reviews and experimental studies. Several medical and laboratory applications of human foreskin fibroblast cell culture have been described, especially when it comes to the use of human foreskin fibroblasts as feeder cells for the cultivation of human embryonic stem cells, in addition to co-culture with other cell types. The culture of foreskin fibroblasts has also been used to: obtain induced pluripotent stem cells; the diagnosis of Clostridium difficile; to test the toxicity and effect of substances on normal cells, especially the toxicity of possible antineoplastic drugs; in viral culture, mainly of the human cytomegalovirus, study of the pathogenesis of other microorganisms; varied studies of cellular physiology and cellular interactions. Fibroblasts are important for cell models for varied application cultures, demonstrating how the preputial material can be reused, making possible new applications.

Level of evidence: Not applicable for this multicentre audit.

Relevant assay to study the adhesion of Plasmodium falciparum-infected erythrocytes to the placental epithelium

In placental malaria, Plasmodium falciparum-infected erythrocytes adhere to the apical plasma membrane of the placental epithelium, triggering an impairment of placental function detrimental to the fetus. The design of anti-adhesion intervention strategies requires a detailed understanding of the mechanisms involved. However, most adhesion assays lack in vivo relevance and are hardly quantitative. Here, we describe a flow cytometry-based adhesion assay that is fully relevant by using apical epithelial plasma membrane vesicles as the adhesion matrix, and being applicable to infected erythrocytes directly isolated from patients. Adhesion is measured both as the percentage of pathogens bound to epithelial membrane vesicles as well as the mean number of vesicles bound per infected erythrocytes. We show that adhesins alternative to those currently identified could be involved. This demonstrates the power of this assay to advance our understanding of epithelial adhesion of infected erythrocytes and in the design of intervention strategies.

Intestinal permeability and systemic infections in critically ill patients: effect of glutamine

OBJECTIVE

This article provides a critical review of the evidence indicating that an increase in intestinal permeability is associated with the installation of bacteremia, sepsis, and the multiple organ failure syndrome and that glutamine in pharmacologic doses reduces the acute increase of intestinal permeability and the infection frequency in critically ill patients.

DATA SOURCE

All studies published until December 2004 about intestinal permeability, bacterial translocation, and glutamine were located by search of PubMed and Web of Science. The reference lists of review articles and primary publications were also examined to identify references not detected in the computer search.

STUDY SELECTION

Clinical and experimental studies investigating the correlation between intestinal permeability, bacterial translocation, and frequency of infections, associated or not with the effect of glutamine administration.

DATA EXTRACTION

Information regarding patient population, experimental design, glutamine doses and routes of administration, nutritional therapy prescribed, methods used to assess intestinal permeability, metabolic variables, and the frequency of infections were obtained from the primary literature.

DATA SYNTHESIS

Intestinal permeability is increased in critically ill patients. The results have not always been consistent, but the studies whose results support the association between intestinal permeability and systemic infections have had better design and more appropriate controls. The administration of glutamine by the intravenous or oral route and at the doses recommended before or immediately after surgery, burns, or the administration of parenteral nutrition has a protective effect that prevents or reduces the intensity of the increase in intestinal permeability. Glutamine reduces the frequency of systemic infections and may also reduce the translocation of intestinal bacteria and toxins, but this has not been demonstrated.

CONCLUSIONS

Glutamine administration improves the prognosis of critically ill patients presumably by maintaining the physiologic intestinal barrier and by reducing the frequency of infections.

Diarrhea in elderly patients due to Clostridium difficile associated with Salmonella and Shigella infection

Clostridium difficile is the main cause of nosocomial diarrhea mainly in elderly hospitalized patients and in nursing homes, but less common in the community. We report three elderly patients living in the community, one frail and two in reasonable good health who recently developed diarrhea due to C. difficile associated with Salmonella group C in two cases and Shigella flexneri in the other. The association with Shigella has not previously been reported and there have only been a few cases with Salmonella. These findings may be important due to the possibility that diarrhea caused by C. difficile associated with other enteric bacteria may be more prevalent than expected in the aging population, thus necessitating awareness and consequently appropriate treatment and follow-up.

Gastrointestinal disorders of the critically ill. Bacterial translocation in the gut

The human gastrointestinal tract is colonized by a dense population of microorganisms, referred to as the bacterial flora. Although the gut provides a functional barrier between these organisms and the host, bacterial translocation is a common event in the healthy person. However, in critically ill patients, with various underlying diseases, this bacterial translocation may lead to infections and consequently to a further reduction in general health status. The mechanism of bacterial translocation is widely, and somehow controversially investigated in vitro and in animal models. In human studies, several diseases have been associated with bacterial translocation. However, methodological shortcomings, insufficient populations and conflicting results leave many open questions. This is also reflected in the various published therapeutic strategies. To overcome this problem more investigations in humans are needed, especially in techniques for detecting bacterial translocation.

Effect of tumor necrosis factor alpha, interferon gamma, and interleukin-4 on bacteria-enterocyte interactions

BACKGROUND

Little is known about the mechanisms involved in bacterial translocation from the intestinal lumen to extraintestinal sites. Because the cytokine cascade associated with sepsis, inflammation, and trauma has been shown to affect intestinal epithelial permeability, experiments were designed to clarify the effects of selected cytokines on bacterial adherence to and internalization by cultured HT-29 and Caco-2 enterocytes.

METHODS

Mature, confluent enterocytes were pretreated 48 to 72 h with tumor necrosis factor alpha (TNF-alpha), interferon gamma, (IFN-gamma), or interleukin-4 (IL-4). Adherence of Listeria monocytogenes, Salmonella typhimurium, Proteus mirabilis, and Escherichia coli was measured by enzyme-linked immunosorbent assay and bacterial internalization was quantified by the gentamicin protection assay. Enterocyte permeability was measured by transepithelial electrical resistance and by flux of 40-kDa fluorescent dextran. Bacterial transmigration across confluent enterocytes was measured using enterocytes cultivated on permeable supports.

RESULTS

TNF-alpha, IFN-gamma, and IL-4 had variable effects on bacterial adherence to HT-29 and Caco-2 enterocytes, although the most consistent finding was increased bacterial adherence associated with INF-gamma. However, none of these cytokines had a noticeable effect on bacterial internalization by either Caco-2 or HT-29 enterocytes. In addition, none of these cytokines had a noticeable effect on the permeability of confluent enterocytes as measured by transepithelial electrical resistance or dextran flux. Bacterial transmigration across confluent HT-29 enterocytes was not altered by TNF-alpha, IFN-gamma, or IL-4; however, IL-4 consistently decreased bacterial transmigration across confluent Caco-2 enterocytes.

CONCLUSIONS

IFN-gamma may augment the epithelial adherence of selected species of enteric bacteria, and IL-4 may act as a barrier-sustaining agent to decrease bacterial migration across the intestinal epithelium.