Tag: Virulence

May 2020 Pod: Discovering novel resistance genes and how bacteria become virulent

In the second episode of Microbiology Lab Pod, a crew consisting of Johan Bengtsson-Palme, Emil Burman, Haveela Kunche and Anna Abramova discusses how to identify novel resistance genes with our special guest Marlies Böhm. We also talk about bacterial virulence: how do bacteria become virulent, how do virulence relate to competition, how do bacteria evade the immune system and can we attenuate virulence using fatty acids?

The specific papers discussed in the pod (with approximate timings) are as follows:

  • 7:15 – Böhm, M.-E., Razavi, M., Flach, C.-F., Larsson, D.G.J., 2020a. A Novel, Integron-Regulated, Class C β-Lactamase. Antibiotics 9, 123. https://doi.org/10.3390/antibiotics9030123
  • 7:15 – Böhm, M.-E., Razavi, M., Marathe, N.P., Flach, C.-F., Larsson, D.G.J., 2020b. Discovery of a novel integron-borne aminoglycoside resistance gene present in clinical pathogens by screening environmental bacterial communities. Microbiome 8. https://doi.org/10.1186/s40168-020-00814-z
  • 9:15 – Makowska, N., et al., 2020. Occurrence of integrons and antibiotic resistance genes in cryoconite and ice of Svalbard, Greenland, and the Caucasus glaciers. Science of The Total Environment 716, 137022. https://doi.org/10.1016/j.scitotenv.2020.137022
  • 20:45 – Marathe, N.P., et al., 2019. Scandinavium goeteborgense gen. nov., sp. nov., a New Member of the Family Enterobacteriaceae Isolated From a Wound Infection, Carries a Novel Quinolone Resistance Gene Variant. Frontiers in Microbiology 10. https://doi.org/10.3389/fmicb.2019.02511
  • 33:45 – Kaito, C., Yoshikai, H., Wakamatsu, A., Miyashita, A., Matsumoto, Y., Fujiyuki, T., Kato, M., Ogura, Y., Hayashi, T., Isogai, T., Sekimizu, K., 2020. Non-pathogenic Escherichia coli acquires virulence by mutating a growth-essential LPS transporter. PLOS Pathogens 16, e1008469. https://doi.org/10.1371/journal.ppat.1008469
  • 43:45 – Lories, B., Roberfroid, S., Dieltjens, L., De Coster, D., Foster, K.R., Steenackers, H.P., 2020. Biofilm Bacteria Use Stress Responses to Detect and Respond to Competitors. Current Biology 30, 1231-1244.e4. https://doi.org/10.1016/j.cub.2020.01.065
  • 45:45 – Lozano, G.L., Bravo, J.I., Garavito Diago, M.F., Park, H.B., Hurley, A., Peterson, S.B., Stabb, E.V., Crawford, J.M., Broderick, N.A., Handelsman, J., 2019. Introducing THOR, a Model Microbiome for Genetic Dissection of Community Behavior. mBio 10. https://doi.org/10.1128/mBio.02846-18
  • 55:45 – Kumar, P., Lee, J.-H., Beyenal, H., Lee, J., 2020. Fatty Acids as Antibiofilm and Antivirulence Agents. Trends in Microbiology. https://doi.org/10.1016/j.tim.2020.03.014
  • 60:15 – Gullberg, E., Cao, S., Berg, O.G., Ilbäck, C., Sandegren, L., Hughes, D., Andersson, D.I., 2011. Selection of resistant bacteria at very low antibiotic concentrations. PLoS Pathogens 7, e1002158. https://doi.org/10.1371/journal.ppat.1002158
  • 61:15 – Larsson, D.G.J., 2018. Risks of using the natural defence of commensal bacteria as antibiotics call for research and regulation. International Journal of Antimicrobial Agents 51, 277–278. https://doi.org/10.1016/j.ijantimicag.2017.12.018
  • 65:15 – Lone, A.G., Bankhead, T., 2020. The Borrelia burgdorferi VlsE Lipoprotein Prevents Antibody Binding to an Arthritis-Related Surface Antigen. Cell Reports 30, 3663-3670.e5. https://doi.org/10.1016/j.celrep.2020.02.081

The podcast was recorded on May 7, 2020. If you want to reach out to us with comments, suggestions or other feedback, please send an e-mail to podcast at microbiology dot se or contact @bengtssonpalme via Twitter. The music that can be heard on the pod is composed by Johan Bengtsson-Palme and is taken from the album Cafe Phonocratique.

Antibiotic resistance driving virulence?

It seriously worries me that a number of indications recently have pointed to that the heavy use of antibiotics does not only drive antibiotic resistance development, but also the development towards more virulent and aggressive strains of pathogenic bacteria. First, the genome sequencing of the E. coli strain that caused the EHEC outbreak in Germany in May revealed not only antibiotic resistance genes, but also is also able to make Shiga toxin, which is causes the severe diarrhoea and kidney damage related to the haemolytic uremic syndrome (HUS). The genes encoding the Shiga toxin are not originally bacterial genes, but instead seem to originate from phages. When E. coli gets infected with a Shiga toxin-producing phage, it becomes a human pathogen [1]. David Acheson, managing director for food safety at consulting firm Leavitt Partners, says that exposure to antibiotics might be enhancing the spread of Shiga toxin-producing phage. Some antibiotics triggers what is referred to as the SOS response, which induces the phage to start replicating. The replication of the phage causes the bacteria to burst, releasing the phages, and with them the toxin [1].

Second, there is apparently an ongoing outbreak of scarlet fever in Hong Kong. Kwok-Yung Yuen, microbiologist at the University of Hong Kong, has analyzed the draft sequence of the genome, and suggests that the bacteria acquired greater virulence and drug resistance by picking up one or more genes from bacteria in the human oral and urogenital tracts. He believes that the overuse of antibiotics is driving the emergence of drug resistance in these bacteria [2].

Now, both of these cases are just indications, but if they are true that would be an alarming development, where the use of antibiotics promotes the spread not only of resistance genes, impairing our ability to treat bacterial infections, but also the development of far more virulent and aggressive strains. Combining increasing untreatability with increasing aggressiveness seems to me like the ultimate weapon against our relatively high standards of treatment of common infections. Good thing hand hygiene still seems to help [3].


  1. Phage on the rampage (http://www.nature.com/news/2011/110609/full/news.2011.360.html), Published online 9 June 2011, Nature, doi:10.1038/news.2011.360
  2. Mutated Bacteria Drives Scarlet Fever Outbreak (http://news.sciencemag.org/scienceinsider/2011/06/mutated-bacteria-drives-scarlet.html?etoc&elq=cd94aa347dca45b3a82f144b8213e82b), Published online 27 June 2011.
  3. Luby SP, Halder AK, Huda T, Unicomb L, Johnston RB (2011) The Effect of Handwashing at Recommended Times with Water Alone and With Soap on Child Diarrhea in Rural Bangladesh: An Observational Study. PLoS Med 8(6): e1001052. doi:10.1371/journal.pmed.1001052 (http://www.plosmedicine.org/article/info%3Adoi%2F10.1371%2Fjournal.pmed.1001052)