Extended-spectrum beta-lactamases in urinary tract infections caused by Enterobacteria: understanding and guidelines for action.

CONTEXT: Beta-lactamases are bacterial enzymes that protect microorganisms from the lethal effects of ß-lactam antibiotics. The production of beta-lactamases is the most important mechanism of resistance to these antibiotics, especially in Gram-negative bacteria. OBJECTIVE: Review the magnitude of the problem of extended-spectrum beta-lactamases (ESBL) in the urological setting and present the fundamental action guidelines on the issue, the main risk factors and the prevention strategies. ACQUISITION OF EVIDENCE: A structured search strategy for patient, problem, intervention, comparison and result was conducted in the PubMed-Medline database to identify the most relevant studies related to the management of patients with urinary tract infection by ESBL-producing microorganisms. We also present a caseload analysis of our center on this issue. SUMMARY OF THE EVIDENCE: ESBL are found in Enterobacteria, mainly Klebsiella sp. and Escherichia coli and are characterized by their hydrolytic ability compared with beta-lactam antibiotics, which entails resistance to penicillin, cephalosporin and aztreonam. They are also associated with resistance to other antibiotics. There is a high risk of infection and colonization by ESBL producers in patients with prolonged hospital stays or who required invasive devices. The prior use of antibiotics and stays in residential care are also risk factors. Prevention programs should focus on preventing nosocomial infection. It is essential that a restrictive policy on the use of antibiotics be implemented. The therapy of choice for severe infections is focused on carbapenems, although their indiscriminate use should be avoided. In uncomplicated lower urinary tract infections, fosfomycin and nitrofurantoin are the best treatment alternatives. CONCLUSION: ESBL-producing strains constitute a true global health problem. Prevention strategies should focus on nosocomial infection. We should not forget, however, that the appearance of these pathogens in community-acquired infections is increasingly frequent. Therapeutic decisions should be based on an understanding of the local distribution of microorganisms and their resistance patterns.