Risk factors and treatment strategies for cholecystitis after metallic stent placement for malignant biliary obstruction: a multicenter retrospective study.

BACKGROUND AND AIMS: Cholecystitis can occur after self-expandable metallic stent (SEMS) placement for malignant biliary obstruction (MBO), but the best treatment option for cholecystitis has not been determined. Here, we aimed to identify the risk factors of cholecystitis after SEMS placement and determine the best treatment option. METHODS: Incidence, treatments, and predictive factors of cholecystitis were retrospectively evaluated in 1084 patients with distal MBO (DMBO) and 353 patients with hilar MBO (HMBO) who underwent SEMS placement at 12 institutions from January 2012 to March 2021. RESULTS: Cholecystitis occurred in 7.5% of patients with DMBO and 5.9% of patients with HMBO. The recurrence rate was significantly lower (P = .043) and the recurrence-free period significantly longer (P = .039) in endoscopic procedures than in percutaneous procedures for cholecystitis treatment. EUS-guided gallbladder drainage (EUS-GBD) was better in terms of technical success, procedure time, and recurrence-free period than endoscopic transpapillary gallbladder drainage. Obstruction across the cystic duct orifice by tumor (P = .015) and by stent (P = .037) were independent risk factors for cholecystitis in DMBO. Cases with multiple SEMS placements (odds ratio [OR], 11; 95% confidence interval [CI], 0.68-190; P = .091) and with gallbladder stones (OR, 2.3; 95% CI ,0.92-5.6; P = .075) had a higher risk for cholecystitis in HMBO. CONCLUSIONS: The incidences of cholecystitis after SEMS placement for DMBO and HMBO were similar. EUS-GBD is the optimal treatment option for patients with cholecystitis after SEMS placement for MBO.

Accuracy of Endoscopic Transpapillary Gallbladder Drainage with Liquid-Based Cytology for Gallbladder Disease.

INTRODUCTION: Gallbladder carcinoma is often difficult to distinguish from benign gallbladder diseases. While the diagnostic accuracy of endoscopic transpapillary gallbladder drainage (ETGD) has been reported, these results were obtained retrospectively. This prospective study aimed to evaluate the cytological diagnostic accuracy of ETGD in patients with gallbladder disease. METHODS: This single-arm prospective clinical trial included a total of 35 patients scheduled to undergo ETGD between March 2017 and September 2019. A 5F pigtail nasobiliary drainage tube was inserted into the gallbladder, and bile was collected over 5 times; if ETGD failed, a drainage tube was placed into the bile duct. The endpoints were, first, the cytological diagnostic accuracy of ETGD and, second, technical success rates and adverse events. RESULTS: Of the 35 patients, 19 were finally diagnosed with gallbladder cancer. The success rate of ETGD tube insertion was 85.7%, and the morphological pattern of the cystic duct with the angle down and located on the right side had a significantly lower success rate for ETGD than that of other cystic duct patterns (odds ratio, 13.5; 95% confidence interval, 1.7-143.7; p = 0.02). Cytological samples were collected 5 times on median. The sensitivity, specificity, and accuracy in all patients were 78.9%, 100%, and 88.6%, respectively, while those in 30 patients with successful ETGD were 87.5%, 100%, and 93.3%, respectively. Adverse events occurred in 3 patients: mild pancreatitis in 1 patient and obstructive jaundice in 2 patients; all complications were resolved with conservative therapy. DISCUSSION/CONCLUSIONS: Cytology using an ETGD tube is useful in differentiating benign and malignant gallbladder diseases (Clinical Trial Registry No. UMIN000026929).

Efficacy of double-balloon enteroscopy-assisted endoscopic balloon dilatation combined with stent deployment for hepaticojejunostomy anastomotic stricture.

BACKGROUND: Hepaticojejunostomy anastomotic stricture (HJAS) is a significant complication of biliary reconstruction surgery. Endoscopic management of HJAS using double-balloon enteroscopy has expanded; however, retrospective reports in this setting are limited. This study aimed to evaluate the efficacy of endoscopic balloon dilatation combined with stent deployment for HJAS. METHODS: This was a single-arm prospective clinical trial involving 40 patients with treatment-naïve HJAS enrolled between March 2016 and August 2019 at four endoscopy units in Japan. For HJAS, plastic stents combined with balloon dilatation were placed for 6 months after initial stenting. The primary outcome was HJ anastomosis patency 12 months after stent removal. RESULTS: The technical success rate was 97.5% (39/40). The failed case required percutaneous transhepatic biliary drainage using the rendezvous technique. All cases achieved successful endoscopic treatment. During the treatment period, four of 40 patients (10%) ended the study protocol due to unrelated causes and were excluded from the primary analysis. Among the 36 patients, clinical success was achieved in 34 (94.4%) patients. The remaining two patients achieved HJAS resolution after an additional 3 months. All 36 patients achieved HJAS resolution. Adverse events were observed in two patients (5.0%) who developed moderate cholangitis. During a median follow-up of 21.3 months, HJAS recurrence was observed in 8.3% (3/36) with a median time to recurrence of 4.3 months and HJ anastomosis patency at 12 months was 94.4%. CONCLUSIONS: Endoscopic balloon dilatation combined with plastic stent deployment for 6 months was a safe and effective strategy for HJAS. (Clinical Trial Registry no. UMIN000020613).

Needle tract seeding after endoscopic ultrasound-guided tissue acquisition of pancreatic tumors: A nationwide survey in Japan.

OBJECTIVES: Endoscopic ultrasound-guided tissue acquisition (EUS-TA) plays a crucial role in the diagnosis of pancreatic tumors. The present study aimed to investigate the current status of needle tract seeding (NTS) after EUS-TA of pancreatic tumors based on a nationwide survey in Japan. METHODS: Patients who underwent surgical resection of primary pancreatic tumors after EUS-TA performed between April 2010 and March 2018 were surveyed. The incidence rates of NTS were determined, and compared in patients with pancreatic ductal adenocarcinomas (PDACs) and other tumors, and in patients who underwent transgastric and transduodenal EUS-TA of PDACs. The detailed features and prognosis of patients with NTS were also assessed. RESULTS: A total of 12,109 patients underwent surgical resection of primary pancreatic tumors after EUS-TA. The overall incidence rate of NTS was 0.330%, and the NTS rate was significantly higher in patients with PDAC than in those with other tumors (0.409% vs. 0.071%, P=0.004). NTS was observed in 0.857% of patients who underwent transgastric EUS-TA, but in none of those who underwent transduodenal EUS-TA. Of the patients with NTS of PDACs, the median time from EUS-TA to occurrence of NTS and median patient survival were 19.3 and 44.7 months, respectively, with 97.4% of NTS located in the gastric wall and 65.8% of NTS resected. The patient survival was significantly longer in patients who underwent NTS resection than in those without NTS resection (P=0.037). CONCLUSIONS: NTS appeared only after transgastric not after transduodenal EUS-TA. Careful follow-up provides an opportunity to remove localized NTS lesions by gastrectomy.

Utility of a 21-gauge Menghini-type biopsy needle with the rolling method for an endoscopic ultrasound-guided histological diagnosis of autoimmune pancreatitis: a retrospective study.

BACKGROUND: The histological diagnosis of autoimmune pancreatitis (AIP) by an endoscopic ultrasound (EUS)-guided approach is still challenging. METHODS: We investigated the utility of the 21-gauge Menghini-type biopsy needle with the rolling method for the histological diagnosis of AIP, in comparison with conventional 22-gauge needles. Among total 28 patients, rate of definitive histological diagnosis, acquired sample area of tissue, rate of histopathological diagnosis of AIP, and adverse events were retrospectively analyzed. RESULTS: Definitive histological diagnoses were successfully accomplished in all 14 patients (100%) treated with a Menghini-type needle, and in 57% of cases (8/14) treated with conventional 22-gauge needles (P < 0.001). The median sample area of the tissue, except for blood contamination, was remarkably larger by the Menghini-type needle than by conventional-type needles (6.2 [IQR, 4.5-8.8] versus 0.7 [IQR, 0.2-2.0] mm2, P < 0.001), and the area per punctures was approximately 4 times larger (1.4 [IQR: 0.9-2.9] versus 0.3 [IQR: 0.1-0.6] mm2/puncture, P < 0.001). Based on the International Consensus Diagnostic Criteria, lymphoplasmacytic infiltration, abundant IgG4-postive cells, storiform fibrosis, and obliterative phlebitis were found in 86%/29%, 64%/0%, 36%/0%, and 7%/0% patients who were treated with the Menghini-type needle and conventional-type needles, respectively. Consequently, histopathological diagnosis with type 1 AIP (lever 1 or 2) was achieved in 9 patients (64%) treated with the Menghini-type needle and in no patient treated with conventional-type needles (P < 0.001). Two patients who had mild post-procedural pancreatitis improved with conservative treatment, and no bleeding occurred in patients treated with the Menghini-type needle. CONCLUSION: EUS-guided rolling method with the 21-gauge Menghini-type biopsy needle is useful for the histopathological diagnosis of AIP, due to its abundant acquisition of good-quality tissue from the pancreas.

Effectiveness, safety, and factors associated with the clinical success of endoscopic biliary drainage for patients with hepatocellular carcinoma: a retrospective multicenter study.

BACKGROUND: Only a few reports have assessed the effectiveness of endoscopic biliary drainage (EBD) in hepatocellular carcinoma (HCC) patients with obstructive jaundice and liver dysfunction. METHODS: This was a retrospective study based on the clinical databases from the Okayama University Hospital and 10 affiliated hospitals. All patients received EBD for jaundice or liver dysfunction. The indication for EBD was aggravation of jaundice or liver dysfunction with intrahepatic bile duct (IHBD) dilation. The technical and clinical success rate, complications, factors associated with clinical failure, and survival duration were evaluated. RESULTS: A total of 107 patients were enrolled in this study. Technical success was achieved in 105 of 107 patients (98.1%). Clinical success was achieved in 85 of 105 patients (81%). Complications related to endoscopic retrograde cholangiography (ERC) occurred in 3 (2.8%) patients. Child-Pugh class C (odds ratio 3.90, 95% confidence interval [CI] 1.47-10.4, p = 0.0046) was the only factor associated with clinical failure, irrespective of successful drainage. The median survival duration was significantly longer in patients with clinical success than in those without clinical success (5.0 months vs. 0.93 months; hazard ratio [HR] 3.2, 95% CI 1.87-5.37). HCC Stage I/II/III (HR 0.57, CI 0.34-0.95, p = 0.032), absence of portal thrombosis (HR 0.52, CI 0.32-0.85, p = 0.0099), and clinical success (HR 0.39, CI 0.21-0.70, p = 0.0018) were significant factors associated with a long survival. CONCLUSIONS: EBD for obstructive jaundice and liver dysfunction in patients with HCC can be performed safely with a high technical success rate. Clinical success can improve the survival duration, even in patients expected to have a poor prognosis. TRIAL REGISTRATION: Retrospectively registered.

Combination of Diclofenac and Sublingual Nitrates Is Superior to Diclofenac Alone in Preventing Pancreatitis After Endoscopic Retrograde Cholangiopancreatography.

BACKGROUND & AIMS: Acute pancreatitis is a major adverse event of endoscopic retrograde cholangiopancreatography (ERCP). Rectal administration of nonsteroidal anti-inflammatory drugs (NSAIDs) decreases the incidence of post-ERCP pancreatitis (PEP). Little is known about the combined effects of sublingual nitrate and NSAIDs. We performed a randomized trial to assess whether the combination of NSAIDs and sublingual nitrate is more effective than NSAIDs alone in preventing PEP. METHODS: In a prospective superiority trial, eligible patients underwent ERCP at 12 endoscopic units in Japan, from March 2015 through May 2018. Patients were randomly assigned to groups given diclofenac suppositories (50 mg) within 15 minutes after the endoscopic procedure alone (diclofenac-alone group, n = 442) or in combination with sublingual isosorbide dinitrate (5 mg) 5 minutes before the endoscopic procedure (combination group, n = 444). The primary endpoint was the occurrence of PEP. RESULTS: PEP developed in 25 patients in the combination group (5.6%), and in 42 patients in the diclofenac-alone group (9.5%) (relative risk 0.59; 95% confidence interval 0.37-0.95; P = .03). Moderate to severe pancreatitis developed in 4 patients (0.9%) in the combination group, and 10 patients (2.3%) in the diclofenac-alone group (relative risk 0.12; 95% confidence interval 0.13-1.26; P = .12). There was no serious adverse event related to the additional administration of sublingual nitrate. CONCLUSIONS: In a randomized controlled trial, we found that prophylaxis with rectal diclofenac and sublingual nitrate significantly reduces the overall incidence of PEP compared with diclofenac suppository alone. ClinicalTrials.gov, no: UMIN 000016274.

Comparison of anticoagulants and risk factors for bleeding following endoscopic sphincterotomy among anticoagulant users: Results from a large multicenter retrospective study.

BACKGROUND AND AIM: Bleeding is an inevitable and often severe complication after endoscopic sphincterotomy (EST). We aimed to investigate the factors associated with post-EST bleeding in patients treated with anticoagulants. METHODS: The data of patients who underwent EST at 15 hospitals between July 2015 and June 2017 were extracted. We investigated the incidence of post-EST bleeding and risk factors for bleeding in patients treated with anticoagulants. RESULTS: One hundred forty-nine patients undergoing EST who met the inclusion criteria were included in this study. The total-EST bleeding (bleeding occurring during or after EST) rate did not differ between the heparin replacement (8.0%, 6/75) and continuation (16.6%, 2/12; P = 0.37) groups of warfarin users. The total-EST-bleeding rate in the heparin replacement group (12.9%, 4/31) was significantly higher than that in the continuation group (0%, 0/31; P = 0.016) in direct oral anticoagulant (DOAC) users. The rate of total-EST bleeding with continuation of DOAC (0%, 0/31) was significantly lower with continuation of warfarin (16.6%, 2/12; P = 0.021). During-EST bleeding (bleeding occurring during EST) (P = 0.0083) and precut (P = 0.033) were significant risk factors for post-EST bleeding in all 149 patients. Heparin replacement was only a significant risk factor for total-EST bleeding (P = 0.033) in DOAC users. CONCLUSION: Heparin replacement was a significant risk factor for post-EST bleeding in DOAC users; however, there was no significant difference between the bleeding rate of heparin replacement and that of continuation groups in patients taking warfarin. During EST and precut were significant risk factors for post-EST bleeding in all patients treated with anticoagulants.

[A Case of a Migrating Central Venous Catheter in the Internal Jugular Vein Diagnosed Using Ultrasonography in a Patient with Right-Sided NeckPain during Chemotherapy].

We report a case of a migrating central venous(CV)catheter with thrombosis in the internal jugular vein that was diagnosed using ultrasonography in a patient complaining of neck pain during chemotherapy. A 57-year-old man with distant metastasis at 1 year after laparoscopic Hartmann operation for rectal cancer was transported to the emergency department by ambulance complaining of severe right-sided neck pain. On that day, his 6th course of chemotherapy with modified FOLFOX6 (levofolinic acid, 5-fluorouracil[5-FU], oxaliplatin[L-OHP])and panitumumab was administered using a CV port that had been placed 3 months previously from the right subclavian vein in the superior vena cava, and verified using radiography. Cervical ultrasonography revealed line migration, with a surrounding low echoic area without a Doppler signal in the right internal jugular vein. This migration was also observed on the radiograph. These findings indicated migration of the CV catheter with thrombosis. After admission, the CV catheter was removed, a new one was inserted from the left subclavian vein in the superior vena cava, and a direct oral anticoagulant was administered to treat the thrombosis. Two days later, his neck pain, which was caused by phlebitis that was probably induced by L-OHP or continuous 5-FU, disappeared. We should consider the possibility of CV catheter issues, including migration or damage, when patients experience neck pain during chemotherapy. Additionally, the present case demonstrated the utility of cervical ultrasonography in diagnosing CV catheter migration, as well as thrombosis.

[Use of a somatostatin analog to improve a patient's condition and the subsequent diagnosis of pancreatic VIPoma:a case report].

A 68-year-old woman with an 11-day history of sudden abdominal pain and severe watery diarrhea was transferred to our hospital due to an exacerbation of renal function despite hydration. After treatment for dehydration and acidemia was provided in our intensive care unit, patient's renal function improved. Contrast-enhanced abdominal computed tomography was finally performed, revealing a hypervascular pancreatic mass with multiple hepatic masses. This imaging finding along with her clinical symptoms indicated watery diarrhea hypokalemia achlorhydria (WDHA) syndrome caused by a pancreatic VIPoma. Somatostatin analog was administered immediately leading to the improvement of her diarrhea and her general condition. As a result, endoscopic ultrasonography-guided fine-needle aspiration could be performed. Consequently, she was diagnosed with a pancreatic neuroendocrine tumor. She then underwent surgical resection of the pancreatic tumor and liver metastasis. As revealed in the immunohistochemical analysis of the excised tumor tissue, VIP was highly expressed, resulting in the final diagnosis of pancreatic VIPoma. Therefore, the immediate use of a somatostatin analog is crucial for improving the patient's general condition and achieving a definitive diagnosis pathologically when a patient is suspected of having a pancreatic VIPoma.

Comparative analysis of methicillin-resistant Staphylococcus aureus isolated from outpatients of dermatology unit in hospitals and clinics.

Community-onset methicillin-resistant Staphylococcus aureus (CO-MRSA) is a causative agent of intractable skin infections. In general, clinical symptoms of hospital outpatients with skin infections are severer than those of clinic patients. Hence, molecular epidemiological features of the CO-MRSA strains from hospital outpatients are predicted to be different from those of clinic patients. Here, we conducted a comparative analysis for CO-MRSA isolates from outpatients with impetigo in hospitals and clinics located in the same district of Tokyo, Japan. Incidence of MRSA infection was higher in hospital outpatients (21.5%, 20/93 isolates) than in clinic patients (14.5%, 121/845 isolates). The resistance rate to clindamycin, which is a common topical antimicrobial agent in dermatology, in the isolates from hospital outpatients (60.0%) was higher than those from clinic patients (31.4%). Proportion of the staphylococcal cassette chromosome (SCC) mec type II, which is a representative type of hospital-acquired MRSA in Japan, in the isolates from hospital outpatients (65.0%) was significantly higher than those from clinic patients (30.6%) (P < 0.01). Multilocus sequence typing showed that the clonal complex 89-SCCmec type II (CC89-II) clone, which exhibits clindamycin resistance, was the most predominant (55.0%) in the isolates from hospital outpatients. On the other hand, all CC8-IV, CC121-V, and CC89-V clones accounted for 60% in clinic patients were susceptible to clindamycin. Our findings suggested that the clindamycin-resistant CC89-II CO-MRSA clone might be more related to skin infections in hospital outpatients than clinic patients.

Advanced hepatocellular carcinoma with hepatic vein tumor thrombosis and renal dysfunction after hepatic arterial infusion chemotherapy effectively treated by liver resection with active veno-venous bypass: report of a case.

BACKGROUND: Hepatocellular carcinoma (HCC) patients with hepatic vein tumor thrombosis (HVTT) extending to the inferior vena cava (IVC) have an extremely poor prognosis. Here we report a case of HCC with HVTT and renal dysfunction after hepatic arterial infusion chemotherapy (HAIC) successfully treated by liver resection and active veno-venous bypass. CASE PRESENTATION: A 77-year-old man was diagnosed to have a large HCC with intrahepatic metastases and HVTT extending to the IVC. Due to the advanced stage, HAIC with cisplatin was performed 13 times in a period of 17 months. As a consequence of this treatment, the size of the main HCC markedly decreased, and the advanced part of the HVTT went down to the root of the right hepatic vein (RHV). However, because of renal dysfunction, HAIC with cisplatin was discontinued and right hepatectomy with patch graft venoplasty of the root of the RHV was performed. Because progression of renal dysfunction had to be avoided, veno-venous bypass was activated during IVC clamping to prevent renal venous congestion and hypotension. Histological examination showed foci of a moderately differentiated HCC with extensive fibrosis and necrosis in the main HCC. Histologically, the HVTT in the RHV showed massive necrosis and tightly adhered to the vascular wall of the RHV. The postoperative function of the remnant liver was good, and no further deterioration of renal function was detected. The patient did not show signs of recurrence 15 month after surgery. CONCLUSION: In the present case, HAIC using cisplatin in combination with hepatic resection and patch graft venoplasty of the IVC provided a good long-term outcome with no HCC recurrence. Renal function was preserved by using active veno-venous bypass during IVC clamping to prevent renal venous congestion and hypotension.

A case of pancreatic arteriovenous malformation identified by investigating the cause of upper abdominal pain associated with acute pancreatitis.

A man in his 60s with epigastric pain was diagnosed with acute pancreatitis and subsequently recovered following conservative treatment. However, because of repeated upper abdominal pain and the formation of a pancreatic pseudocyst, he was transferred to our institution for evaluation. Dynamic computed tomography (CT) scanning confirmed abnormal vessels in the tail of the pancreas and early venous return to the splenic vein in the early arterial phase. Abdominal angiography revealed a racemose vascular network in the tail of the pancreas, confirming the presence of an arteriovenous malformation (AVM) in this region. This AVM was thought to be the cause of the acute pancreatitis, so a distal pancreatectomy was performed. The patient's postoperative course was uneventful, and there has been no recurrence at the 7-month postoperative follow-up. Surgical resection has a low recurrence rate and good outcome;thus, if a pancreatic AVM appears difficult to treat with conservative medical therapy, surgical resection appears to be the definitive treatment.

[A case of Hamman's syndrome associated with acute-onset type 1 diabetes mellitus presenting with abdominal pain].

A 21-year-old female presented at an emergency department with abdominal pain and nausea. Computed tomography (CT) of the chest and abdomen revealed a small amount of mediastinal emphysema in the precardiac area, but the underlying cause could not be identified. On admission, her plasma glucose was 371 mg/dl, glycated hemoglobin (HbA1c) was 14.0%, and blood pH was 6.91. These findings supported a diagnosis of Hamman's syndrome associated with diabetic ketoacidosis. Her diabetic ketoacidosis was managed with insulin and fluid therapy, and the mediastinal emphysema disappeared spontaneously by the time of discharge. Presence of free air of the chest and abdominal cavity must warrant a differential diagnosis of gastrointestinal perforation; however, when the free air is accompanied by diabetic ketoacidosis, it is not necessary to perform urgent endoscopy.

A Case of Cancer of Unknown Primary Presenting with Chylothorax.

A 56-year-old man presented to our hospital with dyspnea on exertion for two months. Bilateral pleural effusions were found, and a close examination revealed a chylothorax, including adenocarcinoma. The primary tumor could not be identified by systemic examination. Therefore, the patient was diagnosed with cancer of unknown primary origin (CUP) presenting with chylothorax. Chemotherapy was administered for CUP, and thoracentesis, pleurodesis, ascites puncture, and nutritional therapy were performed for chylothorax and chylous ascites. Although drainage frequency and tumor marker levels (CA19-9, DUPAN-2, and Span-1) temporarily decreased, disease control deteriorated, and the patient died 12 months after the initial diagnosis.

[A case of ceftriaxone-associated pseudolithiasis in an adult patient that disappeared after the discontinuation of ceftriaxone].

We report a case of a 47-year-old female patient with ceftriaxone (CTRX)-associated pseudolithiasis. CTRX was administered at a dosage of 2g/day for 8 days because of colonic diverticulitis. A routine abdominal computed tomography (CT) scan was performed to investigate the diverticulitis. However, the CT scan demonstrated stones and sludge in the gallbladder, which had not been present before CTRX administration. Therefore, we diagnosed the patient with pseudolithiasis caused by CTRX and stopped CTRX administration. The stones and sludge disappeared 6 days after stopping CTRX administration. This underreported adverse effect of CTRX should be considered when treating both children and adult patients.

Japanese Spotted Fever Associated with Mild Encephalitis/Encephalopathy with a Reversible Splenial Lesion.

A 58-year-old woman had disseminated intravascular coagulation (DIC) and septic shock caused by Japanese spotted fever (JSF). Following treatment with minocycline, her general condition gradually improved; however, her disorientation persisted. Mild encephalitis/encephalopathy with a reversible splenial lesion (MERS) type II was diagnosed based on brain magnetic resonance imaging (MRI) showing a hyperintense area in the splenium of the corpus callosum and bilateral cerebral white matter on diffusion-weighted imaging. Thereafter, her consciousness gradually improved, but she continued to experience difficulty concentrating and attention deficits. MERS type II may take longer to improve than type I, and long-term follow-up is required.

Significant increase in the prevalence of Panton-Valentine leukocidin-positive methicillin-resistant Staphylococcus aureus, particularly the USA300 variant ΨUSA300, in the Japanese community.

IMPORTANCE: USA300 is an MRSA clone producing PVL, a toxin associated with SSTIs. ΨUSA300 is a USA300 variant recently identified in Japan by Takadama et al. (15). Here, we found that the prevalence rate of PVL-positive MRSA in S. aureus was elevated in the Japanese community, and ΨUSA300 accounted for most of them. ΨUSA300 strains have been isolated from several areas in Japan and were associated with deep-seated SSTIs. This study highlighted the emerging threat posed by ΨUSA300 in Japan.