The reduction of l -cystine to l -cysteine in the supernatant of A549 cell culture causes imipenem inactivation

Takemura, Hiromu; Terakubo, Shigemi; Okamura, N; Nakashima, Hideki

doi:10.1016/j.jiac.2017.10.020

Cited by 1 publication

(1 citation statement)

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“…This suggests that the same compound (L-cysteine or other free thiols) plays a major role in regulating the susceptibility of VIM-1-expressing bacteria to cephalosporins. Notably, the finding that the cellular supernatant has an impact on antibiotic susceptibility via reduction of L-cystine to L-cysteine has been reported previously, but the underlying mechanisms have not yet been identified (19). For example, the inactivation of meropenem by cellular supernatants has been reported (19), as has the inactivation of penicillins by L-cysteine (20).…”

Section: Discussionmentioning

confidence: 98%

Klebsiella pneumoniae Expressing VIM-1 Metallo-β-Lactamase Is Resensitized to Cefotaxime via Thiol-Mediated Zinc Chelation

et al. 2019

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Antibiotic-resistant Klebsiella pneumoniae isolates constitute a great clinical challenge. One important resistance mechanism in K. pneumoniae is the metallo-β-lactamases (MBLs), which require zinc for their function. Thus, zinc chelation could be a strategy to resensitize K. pneumoniae to β-lactams. However, the potential role for endogenous zinc chelators for this purpose remains to be explored. The aim was to search for endogenous factors that could resensitize MBL-expressing K. pneumoniae to cefotaxime (CTX). Clinical K. pneumoniae isolates expressing different MBLs were screened for sensitivity to CTX in supernatants from human HT-29 colonic epithelial cells. Factors influencing CTX susceptibility were isolated and identified with chromatographic and biochemical methods. Free zinc was measured with a Zinquin assay, the thiol content was assessed with a fluorometric thiol assay, and the reducing ability of the supernatant was measured with a fluorescent l-cystine probe. Urine samples from healthy volunteers were used to validate findings ex vivo. VIM-1-expressing K. pneumoniae regained susceptibility to CTX when grown in supernatants from HT-29 cells. This effect was mediated via free thiols in the supernatant, including l-cysteine, and could be prevented by inhibiting thioredoxin reductase activity in the supernatant. Free thiols in urine samples appeared to have a similar function in restoring CTX activity against VIM-1-expressing K. pneumoniae in a zinc-dependent manner. We have identified l-cysteine as an endogenous zinc chelator resulting in the resensitization of VIM-1-expressing K. pneumoniae to CTX. These results suggest that natural zinc chelators in combination with conventional antibiotics could be used to treat infections caused by VIM-1-expressing pathogens.

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Section: Discussionmentioning

confidence: 98%