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This award-winning blog supplements the articles in Hospital Infection Control & Prevention.

Pan-resistant New Delhi enzyme transmitted between patients in Rhode Island hospital

Patient-to-patient transmission of the so-called New Delhi strain of carabapenem-resistant Enterobacteriaceae (CRE) in a Rhode Island hospital was recently reported by the Centers for Disease Control and Prevention.

“Clinicians caring for patients infected with such organisms have few, if any, therapeutic options available,” the CDC reports. “CRE containing New Delhi metallo-beta-lactamase (NDM), first reported in a patient who had been hospitalized in New Delhi, India, in 2007 , are of particular concern because these enzymes usually are encoded on plasmids that harbor multiple resistance determinants and are transmitted easily to other Enterobacteriaceae and other genera of bacteria.”

A urine specimen collected on March 4, 2012, from a patient who recently had been hospitalized in Viet Nam, but who was receiving care at a hospital in Rhode Island, was found to have a Klebsiella pneumoniae isolate containing NDM. The isolate was susceptible only to tigecycline, colistin, and polymyxin B. Point-prevalence surveys of epidemiologically linked patients revealed transmission to a second patient on the hematology/oncology unit. These two cases bring to 13 the number of cases of NDM reported in the United States. After contact precautions were reinforced and environmental cleaning was implemented, no further cases were identified. Similarly aggressive infection control efforts can limit the spread of NDM in acute-care medical facilities, the CDC advised.

The paitent had been placed on contact precautions requiring visitors to her room to don gowns and gloves. She was allowed to walk in the hallway if she was continent, performed hand hygiene before leaving the room, and wore a clean garment, but was incontinent at least once while outside her room. On February 15, a urine culture grew two strains of carbapenemase-producing K. pneumoniae. From hospital admission through March 3, the patient was administered a range of antibiotics, including ceftriaxone, cefazolin, ciprofloxacin, metronidazole, piperacillin/tazobactam, meropenem, colistin, fluconazole, and oral and intravenous vancomycin. On March 4, a second urine culture grew carbapenemase-producing K. pneumoniae. The modified Hodge test, a laboratory test for the presence of carbapenemase, was weakly positive. The patient was asymptomatic; her catheter was replaced and a repeat urine culture was negative, without antibiotic therapy.

In light of the patient's unusual travel history and the weakly positive modified Hodge test, the isolate was sent to CDC and was confirmed as CRE containing NDM. After receiving this information, isolation precautions were changed for this patient, prohibiting her from walking outside her room and limiting diagnostic tests or procedures requiring her to leave her room. The medical director and staff members of the hospital infection control department educated medical and nursing staff members about NDM and needed precautions. Topics reviewed included the epidemiology of CRE, specifically NDM, and modes of transmission, gastrointestinal carriage, and limited treatment options for infected patients. The patient was discharged March 26, the CDC reported.