Final answer:
CRE infections are dangerous due to their resistance to multiple antibiotics including carbapenems, making them difficult to treat. Klebsiella species can produce the potent carbapenemase enzyme NDM, significantly limiting treatment options to drugs like tigecycline and colistin.
Step-by-step explanation:
The infection with a carbapenemase-producing Enterobacteriaceae (CRE), such as Klebsiella species found in the urinary tract, is particularly dangerous due to the bacteria's resistance to carbapenems. These antibiotics are often used as a last resort for treating severe infections caused by gram-negative bacteria. The resistance mechanisms employed by CRE include carbapenemase production, active efflux pumps, and alteration of porin channels, all of which can inactivate a broad range of antibiotics.
Further complicating the treatment of CRE infections is the fact that these bacteria are not only resistant to carbapenems but also to multiple classes of antibacterials. In cases such as Marisa's urinary tract infection, caused by Klebsiella pneumoniae, the pathogen was identified as producing NDM, a particularly active carbapenemase enzyme. Although some treatment options remain for CRE, such as tigecycline and colistin, the limited effectiveness and potential toxicity of these drugs present serious challenges in patient care.