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

Abstract

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

Methods: 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.

Results: 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).

Conclusions: 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.

Keywords: Immunosuppression; Intestinal colonization; KPC; Long-term carriage; Selection pressure.