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Outbreak of extensively drug-resistant (XDR) Klebsiella pneumoniae

  • In 2019, an outbreak of a strain of XDR Klebsiella pneumoniae occurred in the state of Mecklenburg-Vorpommern.

  • This Klebsiella pneumoniae strain exhibited resistance to two reserve antibiotics.

  • When outbreaks involving XDR pathogens occur, a particularly high level of awareness and risk-reduction measures are required to prevent cases of transmission.

Antibiotic-resistant Klebsiella pneumoniae are among the most significant causative agents of nosocomial infections, which include urinary tract infections, pneumonia, and sepsis. Infections involving multi-resistant Klebsiella pneumoniae frequently lead to severe or even fatal illness. The 2019 outbreak in Mecklenburg-Vorpommern showed how threatening multi-resistant strains of this pathogen are.

Outbreak in four healthcare facilities

The outbreak took place between June and the end of October 2019. Multi-resistant strains of Klebsiella pneumoniae were detected in four healthcare facilities in total. Seventeen patients were affected in the form of either infection or colonization. Comprehensive measures were initiated to contain and control the outbreak. These included isolation measures, tracing and screening of patients who had come into contact with affected individuals, and notification of patients and the responsible health authorities. In addition, samples of isolates were sent to the National Reference Center for gram-negative bacteria in Bochum, Germany.

Resistance of Klebsiella pneumoniae to carbapenems and colistin

Analysis of the bacterial isolates revealed that the pathogen strain was resistant to two important reserve antibiotics. Thus, the Klebsiella pneumoniae ST307 strain showed resistance to both carbapenems and colistin. In addition to being resistant to colistin, the strain produced CTX-M beta-lactamases, NDM-1 (New Delhi metallo-beta-lactamase), and OXA-48-type enzymes. According to Haller et al., this was Germany’s first reported nosocomial outbreak of a strain of Klebsiella pneumoniae ST307 exhibiting this type of resistance behavior [1].

Examination of the outbreak strain revealed that NDM-1, CTX-M-15 and OXA-48 resistances were encoded on three different plasmids (plasmid 1: pPBIO1953_NDM-1, plasmid 2: pPBIO1953_CTX-M-15, plasmid 4: pPBIO1953_OXA-48) [2]. For example, in addition to NDM-1, other resistance genes and virulence factors, e.g. to disinfectants/minerals (qacEdelta1 [disinfectant resistance], ter [tellurite resistance]), were also encoded on plasmid 1 [2]. With such plasmids, both antibiotic resistance and virulence factors can be passed in an intra- or inter-species transfer.

Need for increased awareness and risk-reduction measures

To improve early recognition of XDR outbreaks, Haller et al. argue that special attention on the part of hospital and laboratory staff is crucial [1]. Early screening and comprehensive isolation measures are needed to prevent the spread of pathogens. The outbreak of a critical pathogen in a region with low levels of endemic disease is a particularly good indicator of how important increased awareness and risk-reduction measures are for avoiding transmission.


  1. Haller S et al. Extensively drug-resistant Klebsiella pneumoniae ST307 outbreak, north-eastern Germany, June to October 2019, Euro Surveill. 2019;24(50):pii=1900734.

  2. Heiden SE et al. A Klebsiella pneumoniae ST307 outbreak clone from Germany demonstrates features of extensive drug resistance, hypermucoviscosity, and enhanced iron acquisition, Genome Medicine (2020) 12:113.