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In vivo tests of nucleic acid‐based metallo‐β‐lactamase inhibitors in cultures of Bacillus cereus 5/B/6
Author(s) -
Wozniak Susan E.,
Shaw Robert W.
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.5.a897-a
Subject(s) - cereus , bacillus cereus , antibiotics , microbiology and biotechnology , chemistry , cephalosporin , bacteria , in vivo , dna , cephalosporin antibiotic , nucleic acid , biochemistry , biology , genetics
β‐Lactam antibiotics such as penicillins and cephalosporins are the most heavily prescribed antibiotics in clinical use today. The major mechanism by which bacteria become resistant to β‐lactam antibiotics is by production of enzymes called β‐lactamases that catalyze the hydrolytic inactivation of these antibiotics. Previously, we reported the discovery of a 10‐residue single‐stranded DNA (ss‐DNA) that is a potent inhibitor of the B. cereus 5/B/6 metallo‐β‐lactamase [R. W. Shaw and S. ‐K. Kim, FASEB Journal 17 , p. A981 (2003)]. We have developed an in vivo assay of metallo‐β‐lactamase inhibitors of the B. cereus 5/B/6 metallo‐β‐lactamase. Buffered solutions (40 μL) of a combination of cephalexin (antibiotic) plus the ss‐DNA (inhibitor) or antibiotic alone were transferred to 1 cm diameter filter paper disks and the disks were placed on the surface of plates inoculated with the metallo‐β‐lactamase‐producing bacterium B. cereus 5/B/6. The control disks contained 0.02 mM cephalexin dissolved in 50 mM MOPS buffer, pH = 7.0. Disks with the inhibitor contained 7.5 mM ss‐DNA and 0.02 mM cephalexin dissolved in 50 mM MOPS buffer, pH = 7.0. Control disks with just β‐lactam antibiotic alone displayed no inhibition of bacterial cell growth after 8 hours of growth at 30° C. On the same plates, disks that included the ss‐DNA displayed a clear inhibition of growth around those disks. Hence, the combination of the ss‐DNA metallo‐β‐lactamase inhibitor with cephalexin was able to kill B. cereus cells under conditions in which cephalexin alone could not. It is notable that the ss‐DNA was stable enough to cause cell death over an eight‐hour period. Supported by TTU HHMI .