Infections with extended-spectrum beta-lactamase-producing enterobacteriaceae: changing epidemiology and drug treatment choices.

Since 2000, Escherichia coli producing CTX-M enzymes (especially CTX-M-15) have emerged worldwide as important causes of community-onset urinary tract infections (UTIs) and bloodstream infections due to extended-spectrum beta-lactamase (ESBL)-producing bacteria. Molecular epidemiology studies suggested that the sudden worldwide increase of CTX-M-15-producing E. coli is mostly due to a single clone named ST131 and that foreign travel to high-risk areas such as the Indian subcontinent might in part play a role in the spread of this clone across different continents. Empirical antibacterial coverage for these resistant organisms should be considered in community patients presenting with sepsis involving the urinary tract especially if a patient recently travelled to a high-risk area. Infections due to ESBL-producing Enterobacteriaceae are associated with a delay in initiation of appropriate antibacterial therapy, which consequently prolongs hospital stays and increases hospital costs. Failure to initiate appropriate antibacterial therapy from the start appears to be responsible for higher patient mortality. The carbapenems are widely regarded as the drugs of choice for the treatment of severe infections due to ESBL-producing Enterobacteriaceae, although comparative clinical trials are lacking. Agents that may be useful for the treatment of ESBL-associated UTIs include fosfomycin, nitrofurantoin and temocillin. If this emerging public health threat is ignored, it is possible that clinicians may be forced in the near future to use the carbapenems as the first choice for empirical treatment of serious infections associated with UTIs originating from the community.