Rapid and accurate diagnosis and subtyping of bacterial carbapenemases are urgently needed due to the increasing prevalence of carbapenem-resistant bacterial infections. By mixing bacteria with a fluorescent probe, β-LEAF (β-lactamase enzyme activated fluorophore), together with three β-lactamase inhibitors ( imipenem for noncarbapenemase β-lactamases, clavulanic acid for type A carbapenemases, and EDTA for type B carbapenemase), we developed a FIBA (Fluorescence Identification of β-Lactamase Activity) platform, which can generate a 95% - 100% sensitivity and specificity for carbapenemase diagnosis and classification within 10 minutes by a single mixing step. FIBA could significantly aid the control and treatment of carbapenem-resistant bacterial infections.

In our previous study, we found that femtosecond pulsed laser can inactivate bacteria more effectively than continuous wave light with UV-C irradiation. We hypothesized that the mechanism of enhanced bacterial inactivation by femtosecond pulsed laser is caused by a nonlinear optical effect due to the high peak intensity. In this experiment, we performed an experiment to compare the bacterial inactivation as the irradiation intensity was varied. This comparative experiment revealed, in the case of UV-C irradiation, that bacterial inactivation effect was the same regardless of the peak intensity and a nonlinear effect of bacterial inactivation does not be confirmed.

Antimicrobial resistance has necessitated the investigation of novel approaches to prolong the use of conventional antibiotics. We hypothesized that using the innovative ‘drug-free’ approach, antimicrobial blue light (aBL), which is a selective generator of ROS in bacteria, we can exploit increases in intracellular ROS to synergize to conventional antibiotics, given that they share a parallel pathway of bactericidal activity. Studies from our group have also suggested the adjuvant potential of aBL that may further promote the effectiveness of antibiotics. Here, we explored the synergistic and adjuvant effects of aBL using different antibiotic classes against bacteria, in vitro and in vivo.

In this study, we first evaluated the effectiveness of antimicrobial blue light (aBL) in vitro against Vibrio vulnificus in planktonic and biofilm cultures. In addition, we assessed aBL for the prevention of potentially lethal burn infections caused by Vibrio vulnificus in mice. We found that aBL was highly effective in killing V. vulnificus in both planktonic and biofilm cultures. Moreover, aBL significantly reduced the bacterial burden in infected mouse burns and reduced the rate of fatal sepsis in mice.

We are investigating use of methylene blue photodynamic therapy (MB-PDT) to treat deep tissue abscesses. Monte Carlo simulations incorporating patient-specific CT images (60 subjects) were utilized to examine the effect of optical properties on the generation of patient-specific treatment plans. We investigated the influence of varying abscess wall absorption and Intralipid-induced scattering within the cavity on threshold optical power and eligibility for MB-PDT. When Intralipid concentration and delivered optical power were optimized simultaneously for each patient, eligibility for MB-PDT increased greatly from 42% to 92%, though this was diminished by the presence of absorption within the cavity.