The clinical and economic burden of community-onset complicated skin and skin structure infections in Korea.

BACKGROUND/AIMS: To investigate epidemiologic characteristics, clinical and economic burdens, and factors associated with mortality in complicated skin and skin structure infection (cSSSI) patients in Korea. METHODS: A retrospective, observational, nationwide study was conducted between April to July 2012 at 14 tertiary-hospitals in Korea. Eligible patients were hospitalized adults with community acquired cSSSI, who underwent surgical intervention and completed treatment between November 2009 and October 2011. Data on demography, clinical characteristics, outcomes and medical resource utilization were collected through medical record review. Direct medical costs were calculated by multiplying quantities of resources utilized by each unit price in Korea. RESULTS: Of 473 patients enrolled, 449 patients (except 24 patients with no record on surgical intervention) were eligible for analysis. Microbiological testing was performed on 66.1% of patients and 8.2% had multiple pathogens. Among culture confirmed pathogens (n = 297 patients, 340 episodes), 76.2% were gram-positive (Staphylococcus aureus; 41.2%) and 23.8% were gram-negative. The median duration of hospital stay was 16 days. Among treated patients, 3.3% experienced recurrence and 4.2% died in-hospital. The mean direct medical costs amounted to $4,195/ person, with the greatest expenses for hospitalization and antibiotics. The in-hospital mortality and total medical costs were higher in combined antibiotics therapy than monotherapy (p < 0.05). Charlson's comorbidity index ≥ 3, standardized early warning scoring ≥ 4, sub-fascia infections and combined initial therapy, were all found to be associated with higher mortality. CONCLUSION: Korean patients with community-onset cSSSI suffer from considerable clinical and economic burden. Efforts should be made to reduce this burden through appropriate initial treatment.

Clinical and Economic Evaluation of Multidrug-Resistant Acinetobacter baumannii Colonization in the Intensive Care Unit.

BACKGROUND: The clinical and economic impact of multidrug-resistant (MDR) Acinetobacter baumannii colonization remains unclear. This study aimed to estimate and compare the mortality rates, length of stay (LOS), and hospitalization costs in the intensive care unit (ICU) for MDR A. baumannii colonized patients and a matched population. MATERIALS AND METHODS: We performed a retrospective propensity score matched cohort study comparing the outcomes of patients with MDR A. baumannii colonization with those of uncolonized subjects matched at the time they were admitted to the ICU between January 2012 and December 2014. RESULTS: During the study period, 375 (7.5%) of the 4,779 patients were colonized with MDR A. baumannii. One hundred and twenty-two MDR A. baumannii colonized patients were compared with 122 uncolonized patients using propensity score matching. MDR A. baumannii colonized patients were likely to have a higher mortality rate compared to uncolonized patients (49.2% vs 32.0%; odds ratio [OR], 3.64). A longer ICU LOS and total admission days were observed in the MDR A. baumannii colonized patient group (4.14 and 4.67 days increase, OR 1.41 and 1.19). MDR A. baumannii colonization patients had an average extra ICU and total admission cost of $1,179 (₩1,261,334) and $1,333 (₩1,422,032) according to a multivariable regression model (OR, 1.27 and 1.17). Multivariable analysis identified the factors affecting ICU cost, which included, MDR A. baumannii colonization (OR = 1.33; P = 0.001), ICU LOS (OR = 1.97; P <0.001), valvular heart disease (OR = 1.12; P = 0.005), invasive devices (OR = 1.15; P = 0.018), and surgery (OR = 1.1; P < 0.001). CONCLUSION: MDR A. baumannii colonization was associated with increased mortality, LOS, and costs in the ICU. A strict infection control program including preemptive isolation for high-risk groups would be helpful for reducing the burden of this infection.

Theoretical study of the ammonia nitridation rate on an Fe (100) surface: a combined density functional theory and kinetic Monte Carlo study.

Ammonia (NH3) nitridation on an Fe surface was studied by combining density functional theory (DFT) and kinetic Monte Carlo (kMC) calculations. A DFT calculation was performed to obtain the energy barriers (Eb) of the relevant elementary processes. The full mechanism of the exact reaction path was divided into five steps (adsorption, dissociation, surface migration, penetration, and diffusion) on an Fe (100) surface pre-covered with nitrogen. The energy barrier (Eb) depended on the N surface coverage. The DFT results were subsequently employed as a database for the kMC simulations. We then evaluated the NH3 nitridation rate on the N pre-covered Fe surface. To determine the conditions necessary for a rapid NH3 nitridation rate, the eight reaction events were considered in the kMC simulations: adsorption, desorption, dissociation, reverse dissociation, surface migration, penetration, reverse penetration, and diffusion. This study provides a real-time-scale simulation of NH3 nitridation influenced by nitrogen surface coverage that allowed us to theoretically determine a nitrogen coverage (0.56 ML) suitable for rapid NH3 nitridation. In this way, we were able to reveal the coverage dependence of the nitridation reaction using the combined DFT and kMC simulations.

Vancomycin-resistant Enterococcus colonization in the intensive care unit: clinical outcomes and attributable costs of hospitalization.

BACKGROUND: The clinical and economic impact of vancomycin-resistant Enterococcus (VRE) colonization remains unclear. Little data are available on factors affecting hospitalization length of stay (LOS) and costs. This study aimed to estimate mortality, LOS, and hospitalization costs for VRE colonized patients compared with a matched hospital population. METHODS: We performed a retrospective propensity score matched cohort study comparing the outcomes of patients with VRE colonization with those of uncolonized subjects matched at the time they were admitted to the intensive care unit (ICU). Between January 2008 and December 2010, we obtained rectal swab cultures within 24 hours of ICU admission to detect VRE colonization. RESULTS: During the study period, 567 (7.2%) of the 7,703 patients were colonized with VRE. There were 199 VRE colonized patients compared with 199 uncolonized patients using the propensity score. VRE colonized patients when compared with uncolonized patients were likely to have a higher case fatality rate (24.6% vs 17.1%; OR, 2.35). Longer total admission days were observed in the VRE colonized patients (28.7 vs 21.4 days; multiplicative effect, 1.25; P = .004). VRE colonization is found to be a significant factor associated with increased ICU cost in the multivariable regression model ($6,065 vs $5,298; multiplicative effect, 1.22; P = .029). Multivariable analysis identified the factors affecting ICU cost as follows: VRE colonization (odds ratio [OR], 1.20; P = .038), ICU length of stay (OR, 1.93; P < .001), ICU type (OR, 1.51; P = .001), valvular heart disease (OR, 2.38; P = .27), hospitalization within 12 months (OR, 1.21; P = .037), and use of invasive devices (OR, 1.28; P = .017). CONCLUSION: Compared with a matched hospital population, VRE colonization was associated with increased mortality, LOS, and costs. Strict infection control programs, including preemptive isolation for a high-risk group, should be helpful.

New algorithm in the basin hopping Monte Carlo to find the global minimum structure of unary and binary metallic nanoclusters.

The basin-hopping Monte Carlo algorithm was modified to more effectively determine a global minimum structure in pure and binary metallic nanoclusters. For a pure metallic Ag55 nanocluster, the newly developed quadratic basin-hopping Monte Carlo algorithm is 3.8 times more efficient than the standard basin-hopping Monte Carlo algorithm. For a bimetallic Ag42Pd13 nanocluster, the new algorithm succeeds in finding the global minimum structure by 18.3% even though the standard basin-hopping Monte Carlo algorithm fails to achieve it.