Klebsiella pneumoniae: Going on the Offense with a Strong Defense.
Klebsiella pneumoniae causes a wide range of infections, including pneumonias, urinary tract infections, bacteremias, and liver abscesses. Historically, K. pneumoniae has caused serious infection primarily in immunocompromised individuals, but the recent emergence and spread of hypervirulent strains have broadened the number of people susceptible to infections to include those who are healthy and immunosufficient. Furthermore, K. pneumoniae strains have become increasingly resistant to antibiotics, rendering infection by these strains very challenging to treat. The emergence of hypervirulent and antibiotic-resistant strains has driven a number of recent studies. Work has described the worldwide spread of one drug-resistant strain and a host defense axis, interleukin-17 (IL-17), that is important for controlling infection. Four factors, capsule, lipopolysaccharide, fimbriae, and siderophores, have been well studied and are important for virulence in at least one infection model. Several other factors have been less well characterized but are also important in at least one infection model. However, there is a significant amount of heterogeneity in K. pneumoniae strains, and not every factor plays the same critical role in all virulent Klebsiella strains. Recent studies have identified additional K. pneumoniae virulence factors and led to more insights about factors important for the growth of this pathogen at a variety of tissue sites. Many of these genes encode proteins that function in metabolism and the regulation of transcription. However, much work is left to be done in characterizing these newly discovered factors, understanding how infections differ between healthy and immunocompromised patients, and identifying attractive bacterial or host targets for treating these infections.
Graduate Program in Immunology, MERGE-ID Track, Sackler School of Biomedical Sciences, Tufts University School of Medicine, Boston, Massachusetts, USA.
Michelle K
MK
Paczosa
Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, USA Joan.Mecsas@tufts.edu.
Joan
J
Mecsas
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D016667:Bacterial Capsules / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D001425:Bacterial Outer Membrane Proteins / Q000276:immunology / Q000378:metabolism*; D024901:Drug Resistance, Multiple, Bacterial; D010861:Fimbriae, Bacterial / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D016867:Immunocompromised Host / Q000276:immunology; D007710:Klebsiella Infections / Q000382:microbiology / Q000473:pathology*; D007711:Klebsiella pneumoniae / Q000187:drug effects / Q000276:immunology / Q000472:pathogenicity*; D008070:Lipopolysaccharides / Q000378:metabolism; D017262:Siderophores / Q000235:genetics; D037521:Virulence Factors / Q000378:metabolism*
D000900:Anti-Bacterial Agents; D001425:Bacterial Outer Membrane Proteins; D008070:Lipopolysaccharides; D017262:Siderophores; D037521:Virulence Factors