It looks like it’s time to pay the piper. The first extensively drug-resistant (XDR) strain of Salmonella typhimurium, called ST313 sublineage II.1, has cropped up in the Democratic Republic of Congo (DRC). This fails to respond to any of the antibiotics that are commonly used in the DRC, except for ciprofloxacin. And to make things worse, one sample has been isolated that shows incomplete response even to this last drug.
S. typhimurium, which many researchers say originated in sub-Saharan Africa some decades ago, has been showing increasingly broad resistance to antibiotics over the last decades. According to the new study which reports the emergence of this new strain of S. typhimurium in the journal Nature Communications on September 19, 2019, this is a threat which will need the close cooperation of microbiologists, geneticists, and epidemiologists, in addition to clinicians and other specialists, if it is to be identified and controlled in different locations.
The exact strain of S. typhimurium producing iNTS in this region is typically ST313, which is known to be resistant to drugs. This has also given rise to two new variants called lineage I and lineage II, which have spread independently to cover most of Africa, fueled by two factors: HIV prevalence and multidrug resistance (MDR). Lineage II infections are now the main cause of iNTS.
An African Salmonella typhimurium ST313 sublineage with extensive drug-resistance and signatures of host adaptation. Sandra Van Puyvelde, Derek Pickard, Koen Vandelannoote, Eva Heinz, Barbara Barbé, Tessa de Block, Simon Clare, Eve L. Coomber, Katherine Harcourt, Sushmita Sridhar, Emily A. Lees, Nicole E. Wheeler, Elizabeth J. Klemm, Laura Kuijpers, Lisette Mbuyi Kalonji, Marie-France Phoba, Dadi Falay, Dauly Ngbonda, Octavie Lunguya, Jan Jacobs, Gordon Dougan & Stijn Deborggraeve. Nature Communications, volume 10, Article number: 4280 (2019). https://doi.org/10.1038/s41467-019-11844-z. https://www.nature.com/articles/s41467-019-11844-z