Photoactivatable antimicrobial agents and therapeutic and diagnostic methods of using same
The present invention provides photosensitizer compounds for use in detecting beta-lactamase activity. Methods and kits that utilize the photosensitizer compounds of the invention for the detection of, quantitation of, and classification or typing of microbial beta-lactamases.
1. A method of measuring susceptibility of beta-lactamase secreting bacteria in a sample to a beta-lactam antibiotic, wherein, the method comprises:
(a) contacting the sample with:
(i) a composition comprising a cephalosporin linker compound linked with two benzophenothiazinium chloride (EtNBS) fluorophores (standard); and
(ii) a composition comprising the beta-lactam antibiotic and the cephalosporin linker compound linked with two EtNBS fluorophores (test sample),
wherein, the EtNBS fluorophores are (Z)-5-((9-(diethylamino)-5H-benzo[a]phenothiazin-5-ylidene)amino)pentanoic acid (EtNBS-COOH) derived fluorophores;
(b) light-activating the standard and the test compositions to produce a fluorescence signal;
(c) quantifying the fluorescence signal with a detector to obtain result;
(d) comparing the test result to the standard result; and
(e) if the amount of the measured fluorescence in the test sample is less than the amount of measured fluorescence in the standard sample, then the β-lactamase secreting bacteria is determined to be susceptible to the β-lactam antibiotic.
2. The method of claim 1 , wherein, the EtNBS fluorophores are conjugated to the cephalosporin linker via amide bond.
3. The method of claim 2 , wherein at least one fluorophore is bound at the 3′ position of the cephalosporin linker.
4. The method of claim 3 , wherein, the cephalosporin linker compound linked with two EtNBS fluorophores is a compound of the structure: