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Physiological and genetic aspects that characterize bacteria of the genera Klebsiella and Enterobacter isolated from sugarcane or human clinical cases

Grant number: 11/14457-7
Support Opportunities:Regular Research Grants
Duration: November 01, 2011 - December 31, 2013
Field of knowledge:Biological Sciences - Microbiology - Biology and Physiology of Microorganisms
Principal Investigator:Heloiza Ramos Barbosa
Grantee:Heloiza Ramos Barbosa
Host Institution: Instituto de Ciências Biomédicas (ICB). Universidade de São Paulo (USP). São Paulo , SP, Brazil
Associated researchers: Mariana Brolezzi Gomes Latarullo ; Nilton Erbet Lincopan Huenuman


Infections by opportunistic pathogens have increased dramatically as a result of modern medicine and invasive procedures. Many of these pathogens can be found in natural reservoirs such as the rhizosphere. In this environment, bacteria of the genera Enterobacter and Klebsiella act in association with plants to promote plant growth by producing phytohormones, facilitating the capture of nutrients and possess the ability to reduce atmospheric nitrogen to ammonia, its combined form, which allows it to assimilation by the plant, a process called biological nitrogen fixation (BNF). Enterobacter spp and Klebsiella spp are commonly found in water and sewage, as well as the intestinal tract of warm-blooded animals and can cause urinary tract infections or as agents of pneumonia. Associated infections are usually acquired in hospitals, especially by immunocompromised patients, requiring the initiation of antimicrobial therapy with broad-spectrum antibiotics, as these genus have antimicrobial resistance to commercial antibiotics. Antibiotics act as an ecological factor that can affect bacterial communities, selecting populations that exhibit intrinsic or acquired resistance mechanisms, which may be mediated by genetic elements such as plasmids and / or integrons. The effects of antibiotics include changes in phylogenetic structures, spread of resistance and disturbances in microsystems. Despite the well-known mechanisms of resistance there is no information on how these genetic events may influence the physiological processes and virulence of opportunistic bacteria of clinical and environmental interest. Thus, through physiological and molecular tests, this study aims to compare data obtained from clinical and environmental samples in relation to antibiotic resistance, virulence factors, ability to fix N2, production of plant growth-promoting substances, antifungal and capacity of colonization of sugarcane micropropagated plants, and to identify their genetic proximity through sequencing of housekeeping genes. The result showed the possibility of selection of clinical strains in rhizosphere environments and hypothesize the acquisition of hospital isolates from the environment. (AU)

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