Fourth national Japanese antimicrobial susceptibility pattern surveillance program: Bacterial isolates from patients with complicated urinary tract infections.

INTRODUCTION: Antimicrobial susceptibility patterns of bacterial pathogens isolated from patients with complicated urinary tract infections were analyzed using the national surveillance data, comprising 793 bacterial strains from eight clinically relevant species. MATERIALS AND METHODS: Data were collected for the fourth national surveillance project from July 2020 to December 2021 by the Japanese Society of Chemotherapy, the Japanese Association for Infectious Disease, and the Japanese Society of Clinical Microbiology. Surveillance was supervised with the cooperation of 43 medical institutions throughout Japan. RESULTS: Fluoroquinolone required a minimum inhibitory concentration (MIC) of 2-64 mg/L to inhibit the 330 tested Escherichia coli strains. The proportion of levofloxacin-resistant E. coli strains increased from 28.6% in 2008 to 29.6% in 2011, 38.5% in 2015, and 44.5% in 2021. The proportion of levofloxacin-resistant strains of Pseudomonas aeruginosa also increased from previous survey results, showing a continuing downward trend. Conversely, the proportion of levofloxacin-resistant strains of Enterococcus faecalis decreased relative to previous reports. Neither multidrug-resistant P. aeruginosa nor carbapenem-resistant Enterobacteriaceae were detected. For methicillin-resistant Staphylococcus aureus (MRSA), the proportion of vancomycin-susceptible strains (MIC of 2 µg/mL) decreased from 14.7% to 7.7%. DISCUSSION: Bacterial strains that produced extended-spectrum ß-lactamase included E. coli (82/330 strains, 24.8%), Klebsiella pneumoniae (11/68 strains, 16.2%), and Proteus mirabilis (4/26 strains, 15.4%). As compared to previous surveillance reports, these strains showed an increase in proportion over the years.

[A Case of Progressive Sarcomatoid Renal Cell Carcinoma Treated with Second-Line Nivolumab after Surgery].

A 69-year-old man visited a local doctor for fever, pain in the left abdomen, and macroscopic hematuria. Computed tomography (CT) revealed hydronephrosis of the left kidney, and he was referred to our hospital. Detailed examinations suggested left-side pyonephrosis due to urothelial cancer, and left-side total nephroureterectomy was performed. Pathological diagnosis was sarcomatoid renal cell carcinoma. Sunitinib administration was started postoperatively for para-aortic lymph node metastasis, which disappeared. However, metastasis to the common iliac lymph node and liver appeared newly 11 months later. Nivolumab was started in combination with radiation thepapy for the lymph node metastases. The patient remains in a stable disease state as of 21 months after nivolumab administration.

[A Case of Right Pyonephrosis Caused by Renal Pelvic Cancer].

A 47-year-old woman who was diagnosed with right pyelonephritis by a local physician, but failed to respond to antimicrobial chemotherapy, was referred to our hospital. Here, the diagnosis of right pyonephrosis was confirmed byabdominal computed tomography(CT). Retrograde pyelography(RP) revealed a severe stricture at the ureteropelvic junction, and it was considered difficult to advance a guidewire through the stricture. Urine cytologywas pseudo-positive ; thus, the possibilityof a malignant tumor of the urinarytract could not be ruled out. Therefore, right nephroureterectomywas performed. The final, histopathological diagnosis was urothelial carcinoma, (G2, pT3). After surgery, the signs and symptoms of the infection were rapidlyameliorated ; however, swelling of the lymph-nodes between the aorta and vena cava was observed, which was considered to be metastasis. Therefore, 4 courses of gemcitabine ＋cisplatin therapywere administered, which resulted in complete resolution of the lymph-node swelling. The patient has remained free of recurrence for 2 years after surgery.

[Possible Diagnosis of Segmental Ureteritis Due to an IgG4-Related Disease that Improved with Steroid Therapy].

A 70-year-old woman was referred to our department after being diagnosed with right hydronephrosis on the basis of computed tomography (CT). CT and magnetic resonance imaging results indicated circumferential wall thickening in the right middle ureter. A retrograde pyelogram revealed an approximately 20 mm stricture in the right middle ureter, and urine cytology results were pseudo-positive. Ureteroscopy was performed due to suspicion of a malignant tumor of the urinary tract, but no malignant lesions were found. Biopsy results showed only the pathology of nonspecific ureteritis, and a diagnosis could not be made even with immunostaining. The patient's blood IgG4 levels were high (317 mg/dl). Based on the diagnostic criteria, the patient was given a possible diagnosis of an IgG4-related disease and treated by the placement ofa ureteral stent and administration of steroid therapy. After starting treatment, blood IgG4 levels decreased and the imaging findings showed improvement. The ureteral stent was removed in the 12th week, and steroid administration was discontinued in the 14th week. No recurrence has since been noted.

[A Case of Localized Amyloidosis of the Ureter Diagnosed by Ureter Biopsy Using a Ureteroscope].

A 42-year-old female visited our hospital with the chief complaint of macrohematuria and left lateroabdominal pain. Computed tomography and retrograde pyelogram showed left hydronephroureter and obstructive uropathy which was 20 mm in diameter in the middle ureter. Urine cytology was negative. Ureter biopsy revealed amyloidosis. Our diagnosis was localized amyloidosis of the ureter, because amyloid was not found in other places in her whole body inspection. Partial ureterectomy was performed. Left renal function was preserved. The patient has been free of recurrence for 18 months after surgery.

Identification of the rate-limiting step of the peroxygenase reactions catalyzed by the thermophilic cytochrome P450 from Sulfolobus tokodaii strain 7.

Cytochrome P450 from the thermoacidophilic crenarchaeon Sulfolobus tokodaii strain 7 (P450st) is a thermophilic cytochrome P450 that shows high tolerance of harsh conditions and is capable of catalyzing some peroxygenase reactions. Here, we investigated the pH dependence of the peroxygenase reactions catalyzed by wild-type P450st and a mutant in which the residues located close to the proximal heme ligand are mutated. Both hydrogen peroxide-driven ethylbenzene hydroxylation and styrene epoxidation by wild-type P450st were found to be activated in weak acidic and weak basic solutions. Under these conditions, the Michaelis constant for hydrogen peroxide (KmH2O2 ) was decreased. The turnover rate (kcat ) of ethylbenzene hydroxylation was increased and followed an S-shaped curve, with an increase in the pH value. The apparent acid dissociation constant (pKa (app) ) of the kcat was 7.0, which suggests that the rate-limiting step of this reaction is deprotonation of the Fe(III) -H2 O2 complex. By introducing a double mutation around the proximal heme ligand, the peroxygenase activity was increased over a wide pH range, and was dramatically increased at pH 5. The spectroscopic properties of this F310A/A320Q mutant indicated that the Lewis acidity of the heme was increased by this mutation. Kinetic investigations showed that the increase in the Lewis acidity of the heme facilitates the reaction rate of the rate-limiting step of peroxygenase reactions and decreases the KmH2O2 value. Differences in the pH dependence of the kcat value between wild-type P450st and the mutant suggest that the rate-limiting step switches to protonation of the ferric-hydroperoxo species (compound 0) under alkaline conditions.

Spectroscopic characterization of the acid-alkaline transition of a thermophilic cytochrome P450.

The spectroscopic properties of thermophilic cytochrome P450 from the thermoacidophilic crenarchaeon Sulfolobus tokodaii strain 7 (P450st) were investigated in acidic and basic solutions. The resting form of ferric-P450st in weakly-acidic and neutral solutions contained a thiolate/H2O coordinated low-spin heme. Below pH 1.5, P450st underwent cleavage of the Fe-S bond and was converted into apo-P450st. Above pH 8, the acid-alkaline transition due to the deprotonation of the water ligand was observed. The produced thiolate/OH⁻-coordinated ferric-P450st was stable at room temperature. The pK(a) value of 8.7 for the transition reflects the protonation properties of the distal side of the heme.