J Bacteriol Virol.  2019 Jun;49(2):53-58. 10.4167/jbv.2019.49.2.53.

Association Between Toxin-antitoxin Systems on Plasmids and Persister Formation in CTX-15-producing Klebsiella pneumoniae ST11 Isolates

• Chung ES
• Kim SY
• Ko KS

• KMID: 2452046
• DOI: http://doi.org/10.4167/jbv.2019.49.2.53

Abstract

We investigated the effect of toxin-antitoxin (TA) systems in bla(CTX-M-15)-bearing plasmids of Klebsiella pneumoniae on persister formation. The persister formation rate was notably high in transconjugants in plasmids bearing TA system than the transconjugants in plasmids bearing no TA systems. Activation of relA and spoT expression was higher in transconjugants with plasmids bearing TA systems. Thus, TA systems in plasmids may contribute to the maintenance of bla(CTX-M-15)-bearing plasmids and host survival via persister formation.

Keyword

persister; toxin-antitoxin (TA) system; CTX-M-15, ppGpp

MeSH Terms

Klebsiella pneumoniae*
Klebsiella*
Plasmids*

Figure

• 

  Figure 1 Persister formation rates in E. coli J53 and transconjugants with TA+ and TA− in the presence of amikacin and streptomycin. Since J53/pM16-13 was resistant to streptomycin, we could not perform a persister assay for this strain. For each individual transconjugant, the persister formation rate was compared to that of J53, and the rates of transconjugants with TA+ and TA− plasmids were also compared.

• 

  Figure 2 The relative expression levels of relA and spoT in transconjugants. The expression levels were compared between transconjugants with TA+ and TA− plasmids. Asterisks indicate significant differences in expression compared with those in the susceptible parental strain: *, p<0.05; **, p<0.01, ***, p<0.001.

• 

  Figure 3 Relative expressions of TA systems, hok, pemK, and vagD, were compared between wild type and persisters against amikacin. J53/pHK02-026 and J53/pM16-13 transconjugants were investigated, having TA systems located on the plasmid harboring CTX-M-15. Asterisks indicate significant differences in expression compared with those in the susceptible parental strain: **, p<0.01, ***, p<0.001.

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