After reviewing the available information, it appears that there is a growing concern regarding the resistance of certain bacteria to tigecycline, a last-resort antibiotic used to treat severe infections caused by drug-resistant bacteria [1]. According to a study published in the Journal of Antimicrobial Chemotherapy, Acinetobacter baumannii and Enterococcus faecium have shown higher resistance to tigecycline [2].

Acinetobacter baumannii is a gram-negative bacterium that can cause a variety of severe infections, including pneumonia, bloodstream infections, and meningitis, particularly in hospitalized patients [3]. The study found that the resistance rate of Acinetobacter baumannii to tigecycline was 22.2% [2].

Enterococcus faecium is a gram-positive bacterium that can cause a range of infections, including urinary tract infections, bacteremia, and endocarditis [4]. The study found that the resistance rate of Enterococcus faecium to tigecycline was 15.4% [2].

It is worth noting that the study also found that the resistance rate of other bacteria, such as Klebsiella pneumoniae and Pseudomonas aeruginosa, to tigecycline was relatively low [2].

In summary, based on the available information, Acinetobacter baumannii and Enterococcus faecium have shown higher resistance to tigecycline, a last-resort antibiotic used to treat severe infections caused by drug-resistant bacteria.

Sources:

1. <https://www.drugpatentwatch.com/antibiotic-resistance-report/>
2. <https://academic.oup.com/jac/article/74/suppl_1/1/5059238>
3. <https://www.cdc.gov/acinetobacter/index.html>
4. <https://www.cdc.gov/hai/organisms/enterococcus/index.html>