Superbugs: a real danger, present and future


Superbugs : WHO has listed multidrug-resistant pathogenic bacteria in three priority groups:

  • Group 1: critical priority. Includes a Acinetobacter baumannii, Pseudomonas aeruginosa and some Enterobacteriaceae such as Klebsiella pneumonie, Escherichia coli and various species of the genera Serratia Y Proteus. All of them are resistant to carbapenems.
  • Group 2: high priority. Includes a Enterococcus faecium (resistant to vancomycin), Staphylococcus aureus (resistant to methicillin and with intermediate sensitivity and resistance to vancomycin), Helicobacter pylori (resistant to clarithromycin), Campylobacter spp. (resistant to fluoroquinolones), Salmonella (resistant to fluoroquinolones) and Neisseria gonorrhoeae (resistant to cephalosporin and fluoroquinolones).
  • Group 3: medium priority. Includes a Streptococcus pneumoniae (no sensitivity to penicillin), Haemophilus influenzae (resistant to ampicillin) and Shigella spp. (resistant to fluoroquinolones).

Superbugs : Resistances that have been brewing for decades

Superbugs : In the 1980s, it was discovered that some strains of Klebsiella pneumonie they were resistant to many beta-lactam antibiotics, a group to which penicillin belongs and which are among the most prescribed. Strains of Klebsiella pneumonie they were capable of producing enzymes called beta-lactamases that chemically inactivated beta-lactam antibiotics. This phenomenon heralded the first wave of antibiotic resistance observed in this bacterium.

It was very bad news and, far from improving, the issue got worse.

Superbugs : In order to treat beta-lactam-resistant infections, a group of antibiotics called carbapenems began to be used, which are a next-generation type of beta-lactam and were very effective for a time.

Unfortunately, in 1996 it was observed that bacteria had developed another enzyme called carbapenemase that had the ability to hydrolyze and destroy carbapenemic antibiotics.

In 2009, the bacteria Klebsiella pneumonie showed a new mechanism of resistance to antibiotics, it was a metallo-beta-lactamase produced by resistant bacteria found in a diabetic patient who had been administered multiple antibiotics after undergoing surgery in a hospital in New Delhi. In the same patient a strain of Escherichia coli which possessed the same kind of resistance mechanism and which had been transmitted to him by Klebsiella pneumonie.

This exchange of resistance between different species greatly affects the future outlook.

Multi-resistance drugs forced the administration of a powerful antibiotic that is considered a last resort: colistin (polymyxin E). This drug alters the cell membrane of the bacteria and thus causes its death, but it must be used with caution because it produces certain toxicity in the human nervous system and kidneys.

In 2010 it was discovered that some strains of Klebsiella pneumonie they were also resistant to colistin. In 2015, the discovery of resistance to colistin mediated by plasmids that carried the mcr-1 gene, both in Escherichia coli like in Klebsiella pneumoniae isolated from humans and animals, raised acute global concern about the possibility of horizontal transfer of this gene between human and animal isolates.

Superbugs : Historically, colistin was first used in the 1950s intravenously. Colistin and polymyxin B have been used for decades in veterinary medicine for prophylactic and therapeutic purposes. Unfortunately the cross resistance between colistin and polymyxin B is almost 100%.

Superbugs : In 2017, Nevada public health officials reported the case of a woman who died in Reno in September 2016 from an incurable infection caused by a strain of Klebsiella pneumoniae that it was resistant to 26 different antibiotics. That is, all available in the United States. 

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