An Outbreak of Infections Caused by a Klebsiella pneumoniae ST11 Clone Coproducing Klebsiella pneumoniae Carbapenemase-2 and RmtB in a Chinese Teaching Hospital

Abstract

Background: Klebsiella pneumoniae carbapenemase (KPC)-producing K. pneumoniae bacteria, which cause serious disease outbreaks worldwide, was rarely detected in Xiangya Hospital, prior to an outbreak that occurred from August 4, 2014, to March 17, 2015. The aim of this study was to analyze the epidemiology and molecular characteristics of the K. pneumoniae strains isolated during the outbreak.

Methods: Nonduplicate carbapenem-resistant K. pneumoniae isolates were screened for blaKPC-2and multiple other resistance determinants using polymerase chain reaction. Subsequent studies included pulsed-field gel electrophoresis (PFGE), multilocus sequence typing, analysis of plasmids, and genetic organization of blaKPC-2locus.

Results: Seventeen blaKPC-2-positive K. pneumoniae were identified. A wide range of resistant determinants was detected. Most isolates (88.2%) coharbored blaKPC-2and rmtB in addition to other resistance genes, including blaSHV-1, blaTEM-1, and aac(3)-IIa. The blaKPC-2and rmtB genes were located on the conjugative IncFIB-type plasmid. Genetic organization of blaKPC-2locusin most strains was consistent with that of the plasmid pKP048. Four types (A1, A2, A3, and B) were detected by PFGE, and Type A1, an ST11, was the predominant PFGE type. A novel K. pneumoniae sequence type (ST1883) related to ST11 was discovered.

Conclusions: These isolates in our study appeared to be clonal and ST11 K. pneumoniae was the predominant clone attributed to the outbreak. Coharbing of blaKPC-2and rmtB, which were located on a transferable plasmid, in clinical K. pneumoniae isolates may lead to the emergence of a new pattern of drug resistance.

Figure 1

Clinical features, molecular characterization, and clonal relatedness of the 17 Klebsiella pneumoniae carbapenemase-producing Klebsiella pneumoniae isolates. The dendrogram was developed using the BioNumerics software platform. key: Klebsiella pneumoniae 1-17; P1-P15: Patient number; IM: Integrative medicine; ES: Epilepsy specialist; GS: Gastrointestinal surgery; CS: Cardiothoracic surgery; WS: Wound secretion; CF: Cerebrospinal fluid; LRT: Lower respiratory tract; Ss: Specimens; RDs: Resistance determinants; PFGE: The pulsed-field gel electrophoresis Types A and B and Subtypes A1–A3; ST: Sequence types ST11 and ST1883, which is a novel sequence type.

Figure 2

Schematic representation of the genetic organization of bla_KPC-2 gene locus. Various genes and their directions of transcription are presented as broad arrows. The area delimited by two dotted lines indicates identical regions. An asterisk (*) indicates pulsed-field gel electrophoresis types.