Multidrug resistance in Gram-negative bacteria that produce extended-spectrum beta-lactamases (ESBLs).

In 1983, just two years after the introduction of the oxymino-beta-lactams to the market , the first extended-spectrum beta-lactamases were isolated in Germany from Klebsiella pneumoniae strains. Since then several outbreaks have been reported in many European countries and the USA, and nowadays in several places worldwide the problem seems to reach endemic dimensions, with rates exceeding 50% in some countries, such as Portugal and Turkey. On the other hand not only K. pneumoniae but also Escherichia coli strains, with Enterobacter aerogenes predominating among the other enterobacteriaceal species, are increasingly reported as ESBL producers. In this review types, molecular characteristics, detection methods, epidemiology as well as interventions for therapy and antibiotic strategies to prevent and control infections caused by ESBL-producing microorganisms, are presented and discussed.