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Febrile Neutropenia in the Critical Care Unit
Published in Cheston B. Cunha, Burke A. Cunha, Infectious Diseases and Antimicrobial Stewardship in Critical Care Medicine, 2020
Perrine Parize, Anne Pouvaret, Paul-Louis Woerther, Frédéric Pène, Olivier Lortholary
Intestinal microbiota, composed of 1011 bacteria per gram of feces, the majority of which are strict anaerobes (>99%), plays the role of barrier regarding the acquisition of exogenous bacteria. This function, also called colonization resistance, can be defined as the process resulting in the removal of bacteria administered by mouth. Under physiologic conditions, colonization resistance allows the clearance of potentially pathogenic bacteria (dominated by aerotolerant gram-negative bacilli, such as enterobacteria, or non-fermenter gram-negative bacilli, such as Pseudomonas spp.), which remain transient or minority. In patients treated for cancer, selective pressure related to exposure to both cytotoxic drugs and antimicrobial agents has a major impact on the intestinal microbiota [22]. As a result, these treatments induce a reduction of the colonization resistance and, in this way, ease the acquisition of exogenous and potentially multidrug resistant (MDR) bacteria [23]. In the same time, they also select indigenous resistant bacteria, while the more susceptible ones are cleared. Finally, intestinal microbiota is found enriched with more and more resistant and potentially pathogenic bacteria and appears as a major reservoir of pathogens, especially for neutropenic patients. Infectious risk is even more significant when these patients are hospitalized in CCU, where they can be exposed to nosocomial infections linked to invasive procedures such as ventilator-associated pneumonias.
Peritonitis (General Considerations)
Published in Peter Sagar, Andrew G. Hill, Charles H. Knowles, Stefan Post, Willem A. Bemelman, Patricia L. Roberts, Susan Galandiuk, John R.T. Monson, Michael R.B. Keighley, Norman S. Williams, Keighley & Williams’ Surgery of the Anus, Rectum and Colon, 2019
Donald E. Fry, Susan Galandiuk
Extra-abdominal causes of infection are common in the peritonitis patient and often occur in the setting of the intensive care unit (ICU) when the patient may have the intra-abdominal process under control, but whilst the patient is immunocompromised from a sustained illness. In selected areas of the world, selective gut decontamination (SGD) has been a commonly employed strategy for critically ill patients to avoid the development of hospital-associated infections. The concept is that the human colon is the source of gram-negative pathogens that drive nosocomial infections and sepsis in the ICU patient. With SGD, oral and systemic antibiotics are administered that cover the aerobic Gram-negative pathogens of the colon. This strategy avoids suppression of the colonic anaerobes that play a role in colonisation resistance and the barrier function of the gut. Current meta-analysis data support reductions in ICU infections (e.g. pneumonia) and associated deaths with the application of this method.75
Introduction: Probiotics and Psychopathology
Published in Martin Colin R, Derek Larkin, Probiotics in Mental Health, 2018
Lactobacillus and Bifidobacterium are the most commercially exploited probiotic microorganisms, used in numerous food products available to consumers. Under normal circumstances (when the host microbiota has not been compromised as a consequence of disease) the gastrointestinal tract is home to some 400-obligate anaerobic bacterial species (Schlundt, 2001; Tannock et al., 2000). Bacterial colonisation begins at birth; bacterial colonisation of the neonates’ gastrointestinal tract begins during the birth process when the neonate comes into contact with maternal cervical and vaginal flora (Bezirtzoglou, 1997). Neonates delivered by caesarean section recieve their bacteria colonisation via contact with the environment. The colonisation of intestinal microflora has a number of beneficial roles, referred to as ‘colonisation resistance’ or the ‘barrier effect’ (Vollaard and Clasener, 1994). This is to say that intestinal flora would resist the recolonization of freshly ingested microorganisms which could include pathogens. As such it could be suggested that dietary manipulation of gut flora in order to increase the relative numbers of ‘beneficial bacteria’ could contribute to the well-being of the host (Schlundt, 2001).
Enterotoxigenic Escherichia coli: intestinal pathogenesis mechanisms and colonization resistance by gut microbiota
Published in Gut Microbes, 2022
Yucheng Zhang, Peng Tan, Ying Zhao, Xi Ma
The gut microbiota is a dynamic and diverse ecosystem composed of trillions of microorganisms that performs a variety of activities, including metabolic regulation, nutritional digestion, immune response regulation, and protection against enteric bacteria.125–127 The gut microbiota possessed the ability to inhibit enteric pathogen colonization and expansion, a property referred to as colonization resistance.128 Existing research is elucidating how the composition of the gut microbiota can offer resistance to enteric pathogens with the development of next-generation sequencing and metabolomics.129 In comparison to other prevalent enteric pathogen, such as Clostridium difficile, Salmonella enterica serovar Typhimurium, and Enterohemorrhagic Escherichia coli, there are a limited studies on colonization resistance of gut microbiota against ETEC. Colonization resistance against ETEC is achieved by the use of numerous mechanisms that remain poorly understood, however there is evidence that both direct pathogen inhibition and indirect pathogen inhibition via host systems may be involved (Figure 4).130
Enterobacteriaceae and Bacteroidaceae provide resistance to travel-associated intestinal colonization by multi-drug resistant Escherichia coli
Published in Gut Microbes, 2022
Matthew Davies, Gianluca Galazzo, Jarne M. van Hattem, Maris S. Arcilla, Damian C. Melles, Menno D. de Jong, Constance Schultsz, Petra Wolffs, Alan McNally, Willem van Schaik, John Penders
The observations of this study highlight the likely importance of discrete species in the dynamics of ESBL-E acquisition, especially within the family Enterobacteriaeceae. The identification of species associated with ESBL-E acquisition necessitates for higher resolution research. The current analyses cannot easily detect how the commensal Enterobacteriaceae population is interacting with the invading ESBL-producing E. coli, so it would be of significant interest to perform experimental studies to explore the competition between various species and strains within this genus and family. The extent at which each member alters the microbiome’s colonization resistance could be discovered. Alternatively, the knowledge on factors facilitating the elimination of previously acquired ESBL-E is still limited, so research on samples taken on additional time points after travel is worthwhile being examined.
The role of the human gut microbiota in colonization and infection with multidrug-resistant bacteria
Published in Gut Microbes, 2021
Irene Wuethrich, Benedikt W. Pelzer, Yascha Khodamoradi, Maria J. G. T. Vehreschild
Colonization resistance refers to the protection by the healthy microbiota against host colonization with pathogenic microorganisms. The search for the definition of a healthy microbiota has not been concluded, but a multitude of independent findings confirm that a high alpha diversity is associated with good health.20,21 The microbiota may however be a reservoir for potentially pathogenic commensals that can turn into causative agents of endogenic infections, so-called pathobionts. A loss in diversity or a disproportionate increase in one or more commensal species often indicates the presence of a disease state. Such shifts are commonly referred to as dysbiosis, even though an exact definition of this term remains to be established. The absence of dysbiosis plays a crucial role in the functionality of colonization resistance.