The effect of ethanol on lactate and base deficit as predictors of morbidity and mortality in trauma.

OBJECTIVE: The objective of this study was to assess the predictive value of lactate and base deficit in determining outcomes in trauma patients who are positive for ethanol. METHODS: Retrospective cohort study of patients admitted to a level 1 trauma center between 2005 and 2014. Adult patients who had a serum ethanol, lactate, base deficit, and negative urine drug screen obtained upon presentation were included. RESULTS: Data for 2482 patients were analyzed with 1127 having an elevated lactate and 1092 an elevated base deficit. In these subgroups, patients with a positive serum ethanol had significantly lower 72-hour mortality, overall mortality, and hospital length of stay compared with the negative ethanol group. Abnormal lactate (odds ratio [OR], 2.607; 95% confidence interval [CI], 1.629-4.173; P = .000) and base deficit (OR, 1.917; 95% CI, 1.183-3.105; P = .008) were determined to be the strongest predictors of mortality in the ethanol-negative patients. Injury Severity Score was found to be the lone predictor of mortality in patients positive for ethanol (OR, 1.104; 95% CI, 1.070-1.138; P = .000). Area under the curve and Youden index analyses supported a relationship between abnormal lactate, base deficit, and mortality in ethanol-positive patients when the serum lactate was greater than 4.45 mmol/L and base deficit was greater than -6.95 mmol/L. CONCLUSIONS: Previously established relationships between elevated lactate, base deficit, and outcome do not remain consistent in patients presenting with positive serum ethanol concentrations. Ethanol skews the relationship between lactate, base deficit, and mortality thus resetting the threshold in which lactate and base deficit are associated with increased mortality.

Blue 470-nm light kills methicillin-resistant Staphylococcus aureus (MRSA) in vitro.

BACKGROUND DATA: In a previous study, we showed that 405-nm light photo-destroys methicillin-resistant Staphylococcus aureus (MRSA). The 390-420 nm spectral width of the 405-nm superluminous diode (SLD) source may raise safety concerns in clinical practice, because of the trace of ultraviolet (UV) light within the spectrum. OBJECTIVE: Here we report the effect of a different wavelength of blue light, one that has no trace of UV, on two strains of MRSA--the US-300 strain of CA-MRSA and the IS-853 strain of HA-MRSA--in vitro. MATERIALS AND METHODS: We cultured and plated each strain, and then irradiated each plate with 0, 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 25, 30, 35, 40, 45, 50, 55, or 60 J/cm2 of energy a single time, using a 470-nm SLD phototherapy device. The irradiated specimens were then incubated at 35 degrees C for 24 h. Subsequently, digital images were made and quantified to obtain colony counts and the aggregate area occupied by bacteria. RESULTS: Photo-irradiation produced a statistically significant dose-dependent reduction in both the number and the aggregate area of colonies formed by each strain (p < 0.001). The higher the dose the more bacteria were killed, but the effect was not linear, and was more impressive at lower doses than at higher doses. Nearly 30% of both strains was killed with as little as 3 J/cm2 of energy. As much as 90.4% of the US-300 and the IS-853 colonies, respectively, were killed with an energy density of 55 J/cm2. This same dose eradicated 91.7% and 94.8% of the aggregate area of the US-300 and the IS-853 strains, respectively. CONCLUSION: At practical dose ranges, 470-nm blue light kills HA-MRSA and CA-MRSA in vitro, suggesting that a similar bactericidal effect may be attained in human cases of cutaneous and subcutaneous MRSA infections.

Visible 405 nm SLD light photo-destroys methicillin-resistant Staphylococcus aureus (MRSA) in vitro.

BACKGROUND: Infections with MRSA remain a growing public health concern, prompting the need to explore alternative treatments instead of the on-going effort to develop stronger drug-based therapies. We studied the effect of 405 nm blue light on two strains of MRSA-US-300 strain of CA-MRSA and the IS853 strain of HA-MRSA-in vitro. METHODS: We cultured and plated each strain, following which bacteria colonies were irradiated with 0, 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 25, 30, 35, 40, 45, 50, 55, or 60 J cm(-2) energy densities-just once-using a Solaris superluminous diode (SLD) device. Specimens were incubated at 35 degrees C for 24 hours. Then, digital images obtained were quantified to obtain colony counts and the aggregate area occupied by bacteria colonies. RESULTS: Blue light irradiation produced a statistically significant dose-dependent reduction in both the number and the aggregate area of colonies formed by each bacteria strain (P<0.001). Maximum eradication of the US-300 (92.1%) and the IS-853 colonies (93.5%) was achieved within 9.2 and 8.4 minutes of exposure, respectively. The longer the irradiation the more bacteria were eradicated. However, the effect was non-linear as increases of energy densities between 1.0 and 15 J cm(-2) resulted in more bacteria death than similar increases between 15 and 60 J cm(-2). CONCLUSION: At low doses, blue light photo-destroys HA-MRSA and CA-MRSA in vitro; raising the prospect that phototherapy may be an effective clinical tool in the on-going effort to stem MRSA infections.