Nosocomial infections within the first month of solid organ transplantation

Selected Topics in Anaerobic Bacteriology

Alteration in the host microbiome at skin and mucosal surfaces plays a role in the function of the immune system, and may predispose immunocompromised patients to infection. Because obligate anaerobes are the predominant type of bacteria present in humans at skin and mucosal surfaces, immunocompromised patients are at increased risk for serious invasive infection due to anaerobes. Laboratory approaches to the diagnosis of anaerobe infections that occur due to pyogenic, polymicrobial, or toxin-producing organisms are described. The clinical interpretation and limitations of anaerobe recovery from specimens, anaerobe-identification procedures, and antibiotic-susceptibility testing are outlined. Bacteriotherapy following analysis of disruption of the host microbiome has been effective for treatment of refractory or recurrent Clostridium difficile infection, and may become feasible for other conditions in the future.

Antibiotic prophylaxis for surgical site infection in people undergoing liver transplantation

BACKGROUND

Surgical site infection is more frequent in liver transplantation than in other types of solid organ transplantation with different antibiotics. Studies have shown that the rate of surgical site infection varies from 8.8% to 37.5% after liver transplantation. Therefore, antimicrobial prophylaxis is likely an essential tool for reducing these infections. However, the literature lacks evidence indicating the best prophylactic antibiotic regimen that can be used for liver transplantation.

OBJECTIVES

To assess the benefits and harms of antibiotic prophylactic regimens for surgical site infection in people undergoing liver transplantation.

SEARCH METHODS

We searched the Cochrane Hepato-Biliary Group Controlled Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, Science Citation Index Expanded and Latin American Caribbean Health Sciences Literature (LILACS). The most recent search was performed on 11 September 2015.

SELECTION CRITERIA

All eligible randomised clinical trials comparing any antibiotic regimen versus placebo, versus no intervention or versus another antibiotic regimen for surgical site infection in liver transplant recipients, regardless of age, sex and reason for transplantation. Quasi-randomised studies and other observational studies were considered for data on harm if retrieved with search results for randomised clinical trials.

DATA COLLECTION AND ANALYSIS

Two review authors selected relevant trials, assessed risk of bias of studies and extracted data.

MAIN RESULTS

The electronic search identified 786 publications after removal of duplicates. From this search, only one seemingly randomised clinical trial, published in abstract form, fulfilled the inclusion criteria of this review. This trial was conducted at Shiraz Transplant Centre, Shiraz, Iran, where investigators randomly assigned a total of 180 consecutive liver transplant recipients. We judged the overall risk of bias of the trial published in abstract form as high. Researchers reported no numerical data but mentioned that 163 participants met the inclusion criteria after randomisation, and hence were included in the analyses. Most probably, the 17 excluded participants were high-risk liver transplant recipients. Trial authors concluded that they could find no differences between the two antibiotic regimens - ceftriaxone plus metronidazole versus ampicillin-sulbactam plus ceftizoxime - when given to liver transplant recipients. Review authors could not reconfirm the analyses because, as it has been mentioned, trial authors provided no trial data for analyses.

AUTHORS' CONCLUSIONS

Benefits and harms of antibiotic prophylactic regimens for surgical site infection in liver transplantation remain unclear. Additional well-conducted randomised clinical trials adhering to SPIRIT (Spirit Protocol Items: Recommendations for Interventional Trials) and CONSORT (Consolidated Standards of Reporting Trials) guidelines are needed to determine the exact role of antibiotic prophylactic regimens in patients undergoing liver transplantation.

Gut microbiota and allogeneic transplantation

The latest high-throughput sequencing technologies show that there are more than 1000 types of microbiota in the human gut. These microbes are not only important to maintain human health, but also closely related to the occurrence and development of various diseases. With the development of transplantation technologies, allogeneic transplantation has become an effective therapy for a variety of end-stage diseases. However, complications after transplantation still restrict its further development. Post-transplantation complications are closely associated with a host's immune system. There is also an interaction between a person's gut microbiota and immune system. Recently, animal and human studies have shown that gut microbial populations and diversity are altered after allogeneic transplantations, such as liver transplantation (LT), small bowel transplantation (SBT), kidney transplantation (KT) and hematopoietic stem cell transplantation (HTCT). Moreover, when complications, such as infection, rejection and graft versus host disease (GVHD) occur, gut microbial populations and diversity present a significant dysbiosis. Several animal and clinical studies have demonstrated that taking probiotics and prebiotics can effectively regulate gut microbiota and reduce the incidence of complications after transplantation. However, the role of intestinal decontamination in allogeneic transplantation is controversial. This paper reviews gut microbial status after transplantation and its relationship with complications. The role of intervention methods, including antibiotics, probiotics and prebiotics, in complications after transplantation are also discussed. Further research in this new field needs to determine the definite relationship between gut microbial dysbiosis and complications after transplantation. Additionally, further research examining gut microbial intervention methods to ameliorate complications after transplantation is warranted. A better understanding of the relationship between gut microbiota and complications after allogeneic transplantation may make gut microbiota as a therapeutic target in the future.

Factors influencing mortality in solid organ transplant recipients with bloodstream infection

Although bloodstream infection (BSI) is a major cause of mortality after solid organ transplantation, information regarding its prognostic factors is scarce. To identify risk factors for 30-day mortality in solid organ transplant (SOT) recipients with BSI, we prospectively recorded all episodes of BSI occurring in adult SOT recipients from January 2007 to October 2014 at a university hospital. We identified 361 consecutive episodes of BSI involving 246 patients. The 30-day case-fatality rate from the onset of BSI was 11.4%. Factors independently associated with 30-day mortality in a logistic regression analysis were shock at presentation (OR 13.658; 95% CI 5.985-31.168), acute graft rejection in the previous 6 months (OR 3.681; 95% CI 1.059-12.795), and a platelet count of <50,000 × 10(9)/L (OR 3.070; 95% CI 1.173-8.038). Kidney recipients were the patients with the best prognosis (OR 0.375; 95% CI 0.156-0.900). Our findings may help to identify SOT recipients with BSI who are at the highest risk of death.

Central nervous system syndromes in solid organ transplant recipients

Solid organ transplant recipients have a high incidence of central nervous system (CNS) complications, including both focal and diffuse neurologic deficits. In the immunocompromised host, the initial clinical evaluation must focus on both life-threatening CNS infections and vascular or anatomic lesions. The clinical signs and symptoms of CNS processes are modified by the immunosuppression required to prevent graft rejection. In this population, these etiologies often coexist with drug toxicities and metabolic abnormalities that complicate the development of a specific approach to clinical management. This review assesses the multiple risk factors for CNS processes in solid organ transplant recipients and establishes a timeline to assist in the evaluation and management of these complex patients.