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Am J Infect Control. 2014 Apr;42(4):376-80. doi: 10.1016/j.ajic.2013.12.001.

Long-term carriage of Klebsiella pneumoniae carbapenemase-2-producing K pneumoniae after a large single-center outbreak in Germany.

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Division of Infectious Diseases and Tropical Medicine, Department of Gastroenterology and Rheumatology, Leipzig University Hospital, Leipzig, Germany. Electronic address:
Institute for Medical Microbiology and Epidemiology of Infectious Diseases, Leipzig University Hospital, Leipzig, Germany; Hospital Hygiene Staff Unit, Leipzig University Hospital, Leipzig, Germany.
Department of Anesthesiology and Intensive Care Medicine, Leipzig University Hospital, Leipzig, Germany.
Department for Infectious Disease Epidemiology, Robert Koch Institute, Berlin, Germany.



The natural progress of intestinal colonization with Klebsiella pneumoniae carbapenemase-2-producing K pneumoniae (KPC-2-KP) is almost unknown.


After a large, single-center outbreak of KPC-2-KP, we analyzed carrier prevalence through retrospective and prospective investigation of intestinal KPC-2-KP carriage 1 month, 3 months, 6 months, 1 year, and 2 years after acquisition, defined as the earliest date of KPC-2-KP detection. Rectal swabs or stool samples were collected at baseline and at each visit and submitted for both culture and KPC-specific polymerase chain reaction. Resolution of intestinal KPC-2-KP carriage was defined as a minimum of 3 consecutive negative polymerase chain reaction test results separated by at least 48 hours.


In patients available for long-term evaluation 26 out of 84 patients (31%) tested negative for KPC-2-KP after 1 month, 14 out of 34 (41%) after 3 months, 17 out of 26 (65%) after 6 months, 14 out of 19 (74%) after 1 year, and 5 out of 6 (83%) after 2 years. Decolonization of KPC-2-KP was hampered in patients with prolonged or repeated hospitalization (P = .044-.140, depending on the time interval). Two patients retested positive for KPC-2-KP after they had previously shown 3 consecutive negative tests. The longest positive KPC-2-KP carrier status so far was observed after nearly 40 months (1,191 days).


The majority of patients experienced spontaneous decolonization within 6 months after acquisition, mainly after discharge from the hospital. However, long-term carriage of >3 years is possible. Appropriate infection control measures must be taken when these patients are readmitted to health care facilities. A series of at least 4 consecutive negative rectal swabs or stool samples separated by sufficient time intervals appears necessary before the declaration of successful KPC-2-KP decolonization is made.


Immunosuppression; Intestinal colonization; KPC; Long-term carriage; Selection pressure

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