Impact of Prolonged Antibiotic Therapy on Commensal Microbial Community Gene Expression.

Plain-language summary

Antibiotics are a mainstay of life-saving interventions used frequently in medical practice to combat infections. These medications not only target the pathogenic bacteria for which they are prescribed but also function against commensal bacterial communities that inhabit the gut, skin, and oropharynx. The role that these native bacterial communities play in normal host function, such as in nutrition and host immunity, is only beginning to be explored, as are the changes in the communities and their function as a result of various alterations of antibiotic use. Short courses of antibiotics have been shown to affect the diversity of native bacterial communities, and to affect the abundance of antibiotic resistance genes present. For example, use of clindamycin in human subjects for 7 days has been demonstrated to result in persistent clindamycin resistance for months or years. The impact of prolonged antibiotic therapy on the host microbiome including both those organisms present and the diversity of antibiotic genes has not been studied, and we have very little understanding of the longitudinal effects of antimicrobial therapy on the genetic repertoire present in human microbial communities. In this study, we will examine changes in the microbiota as well as frequency of antibacterial resistance genes harbored in skin, saliva, and colonic microbiomes longitudinally in subjects on prolonged antimicrobial therapy, as well as household members of the person on antibiotic therapy. Previously well patients with minimal prior antibiotic exposure will be enrolled upon diagnosis of an infection requiring long-term antibiotic therapy, such as osteomyelitis or prosthetic joint infection, prior to starting antibiotic therapy. We will examine the microbiota of the skin, saliva, and gut prior to antibiotics as well as the frequency of antibiotic resistance genes harbored within these microbial communities. We will compare microbial communities and antibiotic resistance gene frequencies before, during and after prolonged course of antibiotics in patients on antibiotics. We will also look for alterations that occur among microbiomes or antibiotic resistance genes among household members of people on antibiotics.

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