[Role of the gut microbiome in the development and transfer of antibiotic resistances]. / Rolle des Darmmikrobioms bei der Entstehung und Weitergabe von Antibiotikaresistenzen.

Antimicrobial resistance (AR) is a natural phenomenon resulting from the exposure of bacteria to antibacterial substances. The intestinal microbiome plays a central role in the development and transmission of AR. In its physiological state, the intestinal microbiome has several mechanisms that contribute to what is referred to as colonization resistance against potentially pathogenic and often multiresistant bacteria. Exposure to broad-spectrum antibiotics can disrupt those mechanisms, facilitating colonization with these pathogens. The persistence of antibiotic selection pressure favors growth of multiresistant bacteria and their dominance within the intestinal microbiota. Under these circumstances, the risk of the development of invasive infections increases. Antibiotic stewardship programs, the use of narrow-spectrum antibiotics, and the administration of substances that protect the intestinal microbiome from antibiotic exposure can prevent these processes. Several interventions such as the administration of probiotics, oral antibiotics, and fecal microbiome transfers are potential strategies for decolonizing patients with multidrug resistant bacteria; to date, however, no intervention has been proven to be consistently effective.

Microbiological and Clinical Aspects of Raoultella spp.

The genus Raoultella was established in 2001. Species of Raoultella and Klebsiella share many ecological, biochemical, clinical, and microbiological features. Given the shortcomings of available technology for species identification in the clinical microbiology laboratory, are practically indistinguishable. Since the late 2000s there has been an increase in case reports of human Raoultella infections. Therefore, several authors are postulating that Raoultella spp. are rare and/or emerging pathogens. Conclusions:Raoultella spp. are very similar to Klebsiella spp. The epidemiology and the clinical relevance of the human Raoultella spp. infections is uncertain and further studies are required. The previous difficulties in the identification of Raoultella spp. and the introduction of more precise identification techniques may explain the recent increase in the number of case reports. Raoultella spp. might be rather underdiagnosed than rare or emerging pathogens.