Febrile urinary tract infection in children: changes in epidemiology, etiology, and antibiotic resistance patterns over a decade.

BACKGROUND: Understanding the epidemiology and prevalence of febrile urinary tract infection (fUTI) in children is important for risk stratification and selecting appropriate urine sample collection candidates to aid in its diagnosis and treatment. PURPOSE: This study aimed to analyze the epidemiology, etiology, and changes in antibiotic susceptibility patterns of the first fUTI in children. METHODS: This retrospective observational cohort study included children younger than 19 years of age who were diagnosed and treated for their first fUTI in 2006-2016. Electronic medical records were analyzed and radiologic images were evaluated. RESULTS: A total of 359 patients (median age, 5.1 months; interquartile range, 3.0-10.5 months) fit the inclusion criteria; of them, 78.0% (n=280) were younger than 12 months old. The male to female ratio was 5.3:1 for patients aged 0-2 months, 2.1:1 for those 3-5 months, and 1.6:1 for those 6-11 months. Beyond 12 months of age, there was a female predominance. Escherichia coli was the leading cause (83.8%), followed by Enterococcus species (6.7%), and Klebsiella pneumoniae (3.6%). Significant yearly increases in the proportions of multidrug-resistant strains (P<0.001) and extended-spectrum beta-lactamase (ESBL) producers (P<0.001) were observed. In patients with vesicoureteral reflux (VUR), the overall recurrence rate was 53.6% (n=15). A significantly higher recurrence rate was observed when the fUTI was caused by an ESBL versus non-ESBL producer (75.0% vs. 30.0%, P=0.03). CONCLUSION: fUTI was most prevalent in children younger than 12 months of age and showed a female predominance in patients older than 12 months of age. The proportion of ESBL producers causing fUTI is increasing. Carbapenems, rather than noncarbapenems, should be considered for treating fUTI caused by ESBL-producing enteric gram-negative rods to reduce short-term recurrence rates in children with VUR.

Production of 8-hydroxydaidzein from soybean extract by Aspergillus oryzae KACC 40247.

Aspergillus oryzae KACC 40247 was selected from among 60 fungal strains as an effective 7,8,4'-trihydroxyisoflavone (8-hydroxydaidzein)-producing fungus. The optimal culture conditions for production by this strain in a 7-L fermentor were found to be 30 °C, pH 6, and 300 rpm. Under these conditions, A. oryzae KACC 40247 produced 62 mg/L of 8-hydroxydaidzein from soybean extract in 30 h, with a productivity of 2.1 mg/L/h. These are the highest production and productivity for 8-hydroxydaidzein ever reported. To increase production, several concentrations of daidzin and of daidzein as precursor were added at several culture times. The optimal addition time and concentration for daidzin were 12 h and 1,248 mg/L, and those for daidzein were 12 h and 254 mg/L respectively. Maximum production and productivity for 8-hydroxydaidzein with the addition of daidzein were 95 mg/L and 3.2 mg/L/h respectively, and those with the addition of daidzin were 160 mg/L and 4.4 mg/L/h respectively.

Hydrolysis of isoflavone glycosides by a thermostable ß-glucosidase from Pyrococcus furiosus.

The recombinant ß-glucosidase from the hyperthermophilic archaeon Pyrococcus furiosus was purified with a specific activity of 330 U/mg for genistin by His-trap chromatography. The specific activity of the purified enzyme followed the order genistin > daidzin > glycitin> malonyl glycitin > malonyl daidzin > malonyl genistin. The hydrolytic activity for genistin was highest at pH 6.0 and 95 °C with a half-life of 59 h, a K(m) of 0.5 mM, and a k(cat) of 6050 1/s. The enzyme completely hydrolyzed 1.0 mM genistin, daidzin, and glycitin within 100, 140, and 180 min, respectively. The soybean flour extract at 7.5% (w/v) contained 1.0 mM genistin, 0.9 mM daidzin, and 0.3 mM glycitin. Genistin, daidzin, and glycitin in the soybean flour extract were completely hydrolyzed after 60, 75, and 120 min, respectively. Of the reported ß-glucosidases, P. furiosusß-glucosidase exhibited the highest thermostability, k(cat), k(cat)/K(m), yield, and productivity for hydrolyzing genistin. These results suggest that this enzyme may be useful for the industrial hydrolysis of isoflavone glycosides.

Production of 10-hydroxystearic acid from oleic acid and olive oil hydrolyzate by an oleate hydratase from Lysinibacillus fusiformis.

A recombinant enzyme from Lysinibacillus fusiformis was expressed, purified, and identified as an oleate hydratase because the hydration activity of the enzyme was the highest for oleic acid (with a k (cat) of 850 min(-1) and a K (m) of 540 µM), followed by palmitoleic acid, γ-linolenic acid, linoleic acid, myristoleic acid, and α-linolenic acid. The optimal reaction conditions for the enzymatic production of 10-hydroxystearic acid were pH 6.5, 35 °C, 4% (v/v) ethanol, 2,500 U ml(-1) (8.3 mg ml(-1)) of enzyme, and 40 g l(-1) oleic acid. Under these conditions, 40 g l(-1) (142 mM) oleic acid was converted into 40 g l(-1) (133 mM) 10-hydroxystearic acid for 150 min, with a molar yield of 94% and a productivity of 16 g l(-1) h(-1), and olive oil hydrolyzate containing 40 g l(-1) oleic acid was converted into 40 g l(-1) 10-hydroxystearic acid for 300 min, with a productivity of 8 g l(-1) h(-1).

Characterization of a ß-glucosidase from Sulfolobus solfataricus for isoflavone glycosides.

The specific activity of a recombinant ß-glucosidase from Sulfolobus solfataricus for isoflavones was: daidzin > glycitin > genistin > malonyl genistin > malonyl daidzin > malonyl glycitin. The hydrolytic activity of this enzyme for daidzin was highest at pH 5.5 and 90°C with a half-life of 18 h, a K (m) of 0.5 mM, and a k (cat) of 2532 s(-1). The enzyme converted 1 mM daidzin to 1 mM daidzein after 1 h with a molar yield of 100% and a productivity of 1 mM h(-1). Among ß-glucosidases, that from S. solfataricus ß had the highest thermostability, k (cat), k (cat)/K (m), conversion yield, and productivity in the hydrolysis of daidzin.

Conversion of oleic acid to 10-hydroxystearic acid by whole cells of Stenotrophomonas nitritireducens.

The optimal reaction conditions for the conversion of oleic acid to 10-hydroxystearic acid by whole cells of Stenotrophomonas nitritireducens were: pH 7.5, 35 °C, 0.05% (w/v) Tween 80, 20 g cells l(-1), and 30 g oleic acid l(-1) in an anaerobic atmosphere. Under these conditions, the cells produced 31.5 g 10-hydroxystearic acid l(-1) over 4 h with a conversion yield of 100% (mol/mol) and a productivity of 7.9 g l(-1) h(-1), indicating that oleic acid was converted completely to 10-hydroxystearic acid, with no detectable byproduct. This is the highest concentration, productivity, and yield of 10-hydroxystearic acid from oleic acid reported thus far.

Characterization of a mannose-6-phosphate isomerase from Thermus thermophilus and increased L-ribose production by its R142N mutant.

An uncharacterized gene from Thermus thermophilus, thought to encode a mannose-6-phosphate isomerase, was cloned and expressed in Escherichia coli. The maximal activity of the recombinant enzyme for L-ribulose isomerization was observed at pH 7.0 and 75°C in the presence of 0.5 mM Cu(2+). Among all of the pentoses and hexoses evaluated, the enzyme exhibited the highest activity for the conversion of L-ribulose to L-ribose, a potential starting material for many L-nucleoside-based pharmaceutical compounds. The active-site residues, predicted according to a homology-based model, were separately replaced with Ala. The residue at position 142 was correlated with an increase in L-ribulose isomerization activity. The R142N mutant showed the highest activity among mutants modified with Ala, Glu, Tyr, Lys, Asn, or Gln. The specific activity and catalytic efficiency (k(cat)/K(m)) for L-ribulose using the R142N mutant were 1.4- and 1.6-fold higher than those of the wild-type enzyme, respectively. The k(cat)/K(m) of the R142N mutant was 3.8-fold higher than that of Geobacillus thermodenitrificans mannose-6-phosphate isomerase, which exhibited the highest activity to date for the previously reported k(cat)/K(m). The R142N mutant enzyme produced 213 g/liter L-ribose from 300 g/liter L-ribulose for 2 h, with a volumetric productivity of 107 g liter(-1) h(-1), which was 1.5-fold higher than that of the wild-type enzyme.

Substrate specificity of ribose-5-phosphate isomerases from Clostridium difficile and Thermotoga maritima.

The activity of ribose-5-phosphate isomerases (RpiB) from Clostridium difficile for D-ribose isomerization was optimal at pH 7.5 and 40 degrees C, while that from Thermotoga maritima for L-talose isomerization was optimal at pH 8.0 and 70 degrees C. C. difficile RpiB exhibited activity only with aldose substrates possessing hydroxyl groups oriented in the right-handed configuration (Fischer projections) at the C2 and C3 positions, such as D-ribose, D-allose, L-talose, L-lyxose, D-gulose, and L-mannose. In contrast, T. maritima RpiB displayed activity only with aldose substrates possessing hydroxyl groups configured the same direction at the C2, C3, and C4 positions, such as the D- and L-forms of ribose, talose, and allose.