Clostridium difficile: emerging public health threat and other nosocomial or hospital acquired infections. Introduction

Antibiotic-Induced Alterations of the Gut Microbiota Alter Secondary Bile Acid Production and Allow for Clostridium difficile Spore Germination and Outgrowth in the Large Intestine

It is hypothesized that the depletion of microbial members responsible for converting primary bile acids into secondary bile acids reduces resistance to Clostridium difficile colonization. To date, inhibition of C. difficile growth by secondary bile acids has only been shown in vitro. Using targeted bile acid metabolomics, we sought to define the physiologically relevant concentrations of primary and secondary bile acids present in the murine small and large intestinal tracts and how these impact C. difficile dynamics. We treated mice with a variety of antibiotics to create distinct microbial and metabolic (bile acid) environments and directly tested their ability to support or inhibit C. difficile spore germination and outgrowth ex vivo. Susceptibility to C. difficile in the large intestine was observed only after specific broad-spectrum antibiotic treatment (cefoperazone, clindamycin, and vancomycin) and was accompanied by a significant loss of secondary bile acids (deoxycholate, lithocholate, ursodeoxycholate, hyodeoxycholate, and ω-muricholate). These changes were correlated to the loss of specific microbiota community members, the Lachnospiraceae and Ruminococcaceae families. Additionally, physiological concentrations of secondary bile acids present during C. difficile resistance were able to inhibit spore germination and outgrowth in vitro. Interestingly, we observed that C. difficile spore germination and outgrowth were supported constantly in murine small intestinal content regardless of antibiotic perturbation, suggesting that targeting growth of C. difficile will prove most important for future therapeutics and that antibiotic-related changes are organ specific. Understanding how the gut microbiota regulates bile acids throughout the intestine will aid the development of future therapies for C. difficile infection and other metabolically relevant disorders such as obesity and diabetes. IMPORTANCE Antibiotics alter the gastrointestinal microbiota, allowing for Clostridium difficile infection, which is a significant public health problem. Changes in the structure of the gut microbiota alter the metabolome, specifically the production of secondary bile acids. Specific bile acids are able to initiate C. difficile spore germination and also inhibit C. difficile growth in vitro, although no study to date has defined physiologically relevant bile acids in the gastrointestinal tract. In this study, we define the bile acids C. difficile spores encounter in the small and large intestines before and after various antibiotic treatments. Antibiotics that alter the gut microbiota and deplete secondary bile acid production allow C. difficile colonization, representing a mechanism of colonization resistance. Multiple secondary bile acids in the large intestine were able to inhibit C. difficile spore germination and growth at physiological concentrations and represent new targets to combat C. difficile in the large intestine.

Non-toxigenic Clostridium sordellii: clinical and microbiological features of a case of cholangitis-associated bacteremia

Toxigenic Clostridium sordellii strains are increasingly recognized to cause highly lethal infections in humans that are typified by a toxic shock syndrome (TSS). Two glucosylating toxins, lethal toxin (TcsL) and hemorrhagic toxin (TcsH) are believed to be important in the pathogenesis of TSS. While non-toxigenic strains of C. sordellii demonstrate reduced cytotoxicity in vitro and lower virulence in animal models of infection, there are few data regarding their behavior in humans. Here we report a non-TSS C. sordellii infection in the context of a polymicrobial bacterial cholangitis. The C. sordellii strain associated with this infection did not carry either the TcsL-encoding tcsL gene or the tcsH gene for TcsH. In addition, the strain was neither cytotoxic in vitro nor lethal in a murine sepsis model. These results provide additional correlative evidence that TcsL and TcsH increase the risk of mortality during C. sordellii infections.

Infection control and intravenous therapy in patients in the community

Recent efforts to reduce infections have been focused within the hospital setting. Early hospital discharge, shorter inpatient stays, day surgery and the movement of patients between acute and long-stay care facilities is likely to make community-acquired infection an increasing problem. There are, or course, universal precautions and general infection control issues to consider when undertaking any clinical procedure, both in hospital and the community, but when administering intravenous therapy (medicines and/or maintenance fluids) specific measures need to be considered. This is especially important if a patient is receiving intravenous therapy at home. There are many reasons why patients may need to receive intravenous therapy in the community and these will all present with specific problems. This paper will discuss some of the infection control procedures one must undertake when administering intravenous therapy to patients in the community.

Infection control and IV therapy in patients with Clostridium difficile

Clostridium difficile is a spore-forming anaerobe belonging to the family Clostridium, with the bacteria being found in low numbers in approximately 5% of the healthy adult population. Together with meticillin-resistant Staphylococcus aureus, it is a major healthcare-associated infection and is responsible for considerable morbidity and mortality. Antibiotics administered to patients can alter normal gut flora, allowing the proliferation of C. difficile and causing antibiotic-associated diarrhoea and colitis. Such diarrhoea, if severe, can lead to dangerous dehydration and even hypovolaemia, especially in the elderly. To limit the physiological impact of diarrhoea, it is sometimes necessary to administer intravenous therapy. Although good clinical practice demands that infection control should be considered in all clinical situations, specific infection control procedures need to be adhered to when administering intravenous therapy to patients with C. difficile.