In the new study, published in the journal Science (Vol. 372, Issue 6547, pp. 1169-1175), scientists investigated Staphylococcus aureus and Pseudomonas aeruginosa that demonstrated resistance to multiple drugs. Their antimicrobial strategy targeted the bacterial hydrogen sulfide (H2S)–mediated defense system. The bacteria rely on the enzyme cystathionine gamma-lyase (CSE) to counter the toxic effects of bactericidal antibiotics (drugs that kill bacteria rather than just slowing their growth). The studies lead to the discovery of small molecules that inhibit bacterial CSE. CSE inhibitors also suppress bacterial tolerance to antibiotics, disrupting biofilm formation and reducing the number of persister bacteria that survive antibiotic treatment. The new molecules made bactericidal antibiotics two- to 15-fold more potent against the bacteria in Petri dishes. By tamping down hydrogen sulfide production, the inhibitors boosted the effects of antibiotics against microorganisms and suppressed bacterial tolerance. @ https://science.sciencemag.org/content/372/6547/1169
Reduction of antibiotic resistance and bacterial tolerance by targeting Inhibitors of bacterial H2S biogenesis
Persister cells, which are found in abundance in biofilms, adopt a quiescent state and survive antimicrobial treatments, seeding disease recurrence and incubating new resistance mutations. Building on work implicating the reactive small-molecule hydrogen sulfide in bacterial defense against antibiotics, Shatalin et al. conducted a structure-based screen for inhibitors of a bacterial hydrogen sulfide–producing enzyme and found a group of inhibitors that act through an allosteric mechanism (see the Perspective by Mah). These inhibitors potentiated bactericidal antibiotics in vitro and in mouse infection models. They also suppressed persister bacteria and disrupted biofilm formation. This strategy of taking out persister cells may be promising for treating recalcitrant infections and holding the line against drug-resistant bacteria.
Science , abd8377, this issue p. ; see also abj3062, p. 
Emergent resistance to all clinical antibiotics calls for the next generation of therapeutics. Here we report an effective antimicrobial strategy targeting the bacterial hydrogen sulfide (H2S)–mediated defense system. We identified cystathionine γ-lyase (CSE) as the primary generator of H2S in two major human pathogens, Staphylococcus aureus and Pseudomonas aeruginosa , and discovered small molecules that inhibit bacterial CSE. These inhibitors potentiate bactericidal antibiotics against both pathogens in vitro and in mouse models of infection. CSE inhibitors also suppress bacterial tolerance, disrupting biofilm formation and substantially reducing the number of persister bacteria that survive antibiotic treatment. Our results establish bacterial H2S as a multifunctional defense factor and CSE as a drug target for versatile antibiotic enhancers.