Klebsiella pneumoniae bacteremia revisited: Comparison between 2007 and 2017 prospective cohorts at a medical center in Taiwan.

BACKGROUND: Community onset K. pneumoniae bacteremia (KPB) is a major problem in Taiwan for decades. We aimed to revisit the role of virulent genotype K1/K2 and possible predisposing factors, compared to our published 2007 cohort. METHODS: All adult patients with monomicrobial KPB during 2017 at a medical center in Taiwan were prospectively enrolled. We genotyped the major K types of K. pneumoniae strains, and analyzed the role of prior use of antibiotic or proton pump inhibitor (PPI). RESULTS: A total of 213 cases were enrolled. Compared to our previous 2007 study (n = 231), there was a higher percentage of patients with community onset bacteremia (75% vs. 60%, p = 0.003). The overall mortality rate was lower in 2017 (23% vs. 32%, p = 0.02), while the rates of antimicrobial resistance (all classes) were higher in 2017. There were 40 cases of liver abscesses in 2017 (19%), with an overall mortality rate of 7.5%. The prevalence of K1 was similar (16% in 2017 vs. 19% in 2007), but the prevalence of K2 decreased significantly (7% in 2017 vs. 17% in 2007, p = 0.001). After excluding 39 cases without data of recent medication use, 48 of 174 (28%) of patients had received a PPI within 90 days. Patients with recent PPI use had more complicated underlying illnesses, higher antimicrobial resistance, and higher in-hospital mortality, but was negatively associated with liver abscess (4% vs. 24%, p = 0.002). Of patients with community-acquired bacteremia, 51% used antibiotics within 90 days. After excluding 37 patients received antibiotics within 14 days before the detection of bacteremia, patient with antibiotic use within 15-90 days had higher Pittsburgh bacteremia scores (4.5 vs. 2.7, p = 0.04), creatinine levels, and frequency of recent surgery, but was not associated with liver abscess (21% vs. 31%, p = 0.33). DISCUSSION: In summary, after a decade, community onset KPB is still prevalent (1.3 case per 1000 emergency department visit). K1 remains to be the dominant genotype. The association of prior ampicillin/amoxicillin or PPIs use for liver abscess is not confirmed.

Positioned substituent effect on self-assembly behaviors of perylene diimide derivatives on graphite.

Three kinds of π-conjugated perylenetetracarboxylic diimide (PTCDI)-based organic functional derivatives, i.e., N,N'-di(2-ethylhexyl)-3,4,9,10-perylene diimide (molecule 1), N,N'-di(2-ethylhexyl)-1,7-dithien-2-yl-3,4,9,10-perylene diimide (molecule 2), N,N'-di(2-ethylhexyl)-1,7-di(2-bromothien-5-yl)-perylene-3,4,9,10-perylene diimide (molecule 3), have been prepared and investigated by using a scanning tunneling microscopy under ambient conditions. All of them can form long-ranged ordered self-assembled monolayer (SAM) with two different phase structures on highly oriented pyrolitic graphite (HOPG) surface. Coexistence of the two phases in the formed SAMs depends strongly on cooperation of various interactions including the molecule-substrate and molecule-molecule. Orientation of the molecular perylene cores primarily governs the molecular orientation in the SAMs by π-π interaction of the molecule-substrate through uttermost matching the graphite surface lattice. At the same time, the branched alkyl-chain substituents at N-sites can adjust intermolecular distances through conformation change while cyclic π-conjugated substituents at bay-positions lead to molecular rotation movement on HOPG, driven by the decreased molecule-substrate interaction caused by distortion of the perylene cores and the intermolecular interaction among the adjacent bay-substituents with rotation conformation change. In addition, the lateral forces from rotation conformation change of the bay-position substituents can also be strong enough to keep the orientation of the perylene cores unchanged. DFT calculation results further reveal the formation mechanisms for the three molecular self-assembly systems. These findings distinctly show that the SAM structures based on the π-conjugated PTCDI-based organic functional derivative molecules can be precisely modulated through introducing suitable substituents at both N- and bay-positions on the PTCDI core.

Variable lengths of stay among ischemic stroke subtypes in Chinese general teaching hospitals.

BACKGROUND: Length of stay (LOS) is one of the most important quantitative indexes that measures health service utilization within a hospital. Many studies have examined the association of three major stroke categories with LOS. Our aim is to investigate the differences of LOS among ischemic stroke subtypes, results from which are helpful to healthcare providers and government agencies to improve health care delivery efficiency. METHODOLOGY/PRINCIPAL FINDINGS: Using the Beijing Municipal Health Bureau's hospitalization summary reports, we performed a retrospective study among first-ever in-hospital patients with ischemic stroke (ICD-10 I63) in three general teaching hospitals in Beijing, China, from 2006 to 2010 with generalized linear model. In our study, 5,559 patients (female, 36.0%; age, 64.4 ± 12.9 years) were included. The estimated mean LOS of ischemic stroke was 17.4 ± 1.8 days. After adjusting for confounders, LOS of lacunar infarction (14.7 days; p<0.001) and LOS of small cerebral infarction (17.0 days; p=0.393) were shorter than that of single cerebral infarction (17.9 days, p<0.001). LOS of multi-infarct (19.0 days; p=0.028), brainstem infarction (19.3 days; p=0.045), basal ganglia infarction (18.5 days; p=0.452) and other subtypes of ischemic stroke (18.9 days; p=0.327) were longer than that of single cerebral infarction. CONCLUSIONS: LOS of ischemic stroke patient differes across single cerebral infarction, lacunar infarction, multi-infarct and brainstem infarction patients. The ascending order of LOS was lacunar infarction, small cerebral infarction, single cerebral infarction, basal ganglia infarction, other subtypes of ischemic stroke, multi-infarct and brainstem infarction.