Successful treatment of carbapenemase producing Enterobacteriaceae peritonitis: 'Old therapy for a new bug'.

Multidrug-resistant organisms cause significant morbidity and mortality. Infections due to resistant gram-negative bacilli are increasingly being reported. For years, carbapenem antibiotics have been successfully used to treat infections due to resistant Enterobacteriaceae, such as and , including those producing extended spectrum β-lactamases, a subset of β-lactamase enzymes that confer broad resistance to penicillins and cephalosporins. More recently, carbapenem-resistant Enterobacteriaceae have emerged as pathogenic organisms, which confer broad resistance to most β-lactam antibiotics including 'last-line' carbapenems. However, different types of carbapenemases confer diverse spectra of antibiotic resistance. Here, we describe the case of an 84-year-old lady on peritoneal dialysis (PD) for 3 years who, on developing carbapenem-resistant PD peritonitis, was successfully treated with colistin, an antimicrobial agent first used in the 1950s.