Enterobacteriaceae produttrici di ß-lattamasi a spettro esteso

Abstract

The topic of this thesis is the antibiotic resistance, with this term we define the ability of pathogenic microorganisms to survive, and consequently ' ' resist ' ' to the action of the most common antibiotics. This phenomenon is an extended problem throughout the world that is negatively reflected with several consequences in the treatment of infectious diseases (Sibhghatulla Shaikh, 2014). There are two types of resistance, one natural and one acquired, which is established following the activation of mechanisms of adaptation by the microorganism. The acquired resistance is through a mutation of its genetic heritage, which makes it insensitive against antibiotics to which it was previously rather sensitive. The strains, in which these mutations occur, are also able to transfer the mutant characters to the progeny, via the vertical pathway. Another possibility corresponds to other microorganisms of different species, for which it happens by horizontal way. Use and abuse of antibiotics in human medicine, agriculture and veterinary medicine are the possible primary reason that has contributed mainly to the development of this event. The public opinion, however, argues that the main responsibility is attributable to the use of antibiotics in the zootechnical field. Although for about fifteen years it is possible to use antibiotics in animal feed only in cases of real necessity and under a strict veterinary control (Macrì, 2019). The main microorganisms that are resistant to different antibiotics belong to the family Enterobacteriaceae, they produce enzymes the ESBL (Extended spectrum β-lactamase), which hydrolyse the β-lactam ring, which represents the common structure of β-lactam antibiotics. They are widely disseminated in both nosocomial and community environments. This leads to a significant risk of infection for particular types of patients. Patients who are particularly at risk are those who have been defedated, geriatric, or suffering from chronic diseases or neoplasms, patients with frequent and long-lasting antibiotic therapies, vesical catheter carriers and guests of long-term rehabilitation and/or geriatric institutes. It is very important that the figures involved in the control of the hospital infections, thanks to the knowledge of the risk factors for the acquisition and the evolution of these resistant antibiotic microorganisms, are updated on the data epidemiologic aspects of the microbial ecology of their hospital in order to properly manage patients affected by these infections. In fact, the choice of adequate antibiotic therapy is essential from the outset to have a positive prognosis of the patient (Gattuso, et al., 2009).