Prevalence of antimicrobial resistant genes in Bacteroides spp. isolated in Oita Prefecture, Japan.

INTRODUCTION: Bacteroides spp. are the most common anaerobic bacteria isolated from the human gastrointestinal tract. Several resistant genes are present in Bacteroides spp. However, most studies have focused on the prevalence of the cfiA gene in Bacteroides fragilis alone. We assessed the susceptibility to antimicrobial agents and the prevalence of cepA, cfiA, cfxA, ermF, nim, and tetQ genes in Bacteroides strains isolated from clinical specimens in our hospital. METHODS: We isolated 86 B. fragilis and 58 non-fragilis Bacteroides strains from human clinical specimens collected from January 2011 to November 2021. Resistance against piperacillin (PIPC), cefotaxime (CTX), cefepime (CFPM), meropenem (MEPM), clindamycin, and minocycline was determined. RESULTS: The resistant rates of penicillins and cephalosporins in non-fragilis isolates were significantly higher than those in B. fragilis isolates. In B. fragilis isolates, the resistant rates of PIPC, CTX, and CFPM in cfxA-positive isolates were significantly higher than those in cfxA-negative isolates (71% vs. 16%, 77% vs. 19%, and 77% vs. 30%, respectively). Thirteen B. fragilis isolates harbored the cfiA gene, two of which were resistant to MEPM. Six of the 13 cfiA-positive B. fragilis isolates were heterogeneously resistant to MEPM. CONCLUSION: It is important to evaluate the use of MEPM as empirical therapy for Bacteroides spp. infections, considering the emergence of carbapenem resistance during treatment, existence of MEPM-resistant strains, and heterogeneous resistance.

Septic shock due to Yersinia pseudotuberculosis infection in an adult immunocompetent patient: a case report and literature review.

BACKGROUND: Yersinia pseudotuberculosis infection can occur in an immunocompromised host. Although rare, bacteremia due to Y. pseudotuberculosis may also occur in immunocompetent hosts. The prognosis and therapeutic strategy, especially for immunocompetent patients with Y. pseudotuberculosis bacteremia, however, remains unknown. CASE PRESENTATION: A 38-year-old Japanese man with a mood disorder presented to our hospital with fever and diarrhea. Chest computed tomography revealed consolidation in the right upper lobe with air bronchograms. He was diagnosed with pneumonia, and treatment with intravenous ceftriaxone and azithromycin was initiated. The ceftriaxone was replaced with doripenem and the azithromycin was discontinued following the detection of Gram-negative rod bacteria in 2 sets of blood culture tests. The isolated Gram-negative rod bacteria were confirmed to be Y. pseudotuberculosis. Thereafter, he developed septic shock. Doripenem was switched to cefmetazole, which was continued for 14 days. He recovered without relapse. CONCLUSIONS: We herein report a case of septic shock due to Y. pseudotuberculosis infection in an adult immunocompetent patient. The appropriate microorganism tests and antibiotic therapy are necessary to treat patients with Y. pseudotuberculosis bacteremia.

A retrospective test for a possible relationship between linezolid-induced thrombocytopenia and hyponatraemia.

WHAT IS KNOWN AND OBJECTIVE: Thrombocytopenia is one of the typical adverse events caused by linezolid (LZD). Recently, some cases of severe hyponatraemia occurring while receiving LZD have been reported. This study investigated a possible relationship between LZD-induced hyponatraemia and thrombocytopenia and identified the risk factors for hyponatraemia and/or thrombocytopenia. METHODS: In this retrospective, single-centre, observational cohort study, 63 hospitalized patients aged over 18 years who received intravenous injection of LZD for more than seven consecutive days in Oita University Hospital between April 2015 and March 2018 were analysed. RESULTS: Thrombocytopenia occurred in 25 (39.7%) patients and hyponatraemia in 11 (17.5%) patients. Seven of 11 patients with hyponatraemia had concurrent thrombocytopenia. Although both serum sodium level and platelet count declined in most patients who developed hyponatraemia, no significant association between thrombocytopenia and hyponatraemia was found. Creatinine clearance level (Ccr) was significantly lower not only in the thrombocytopenia (vs no-thrombocytopenia) but also in the hyponatraemia group (vs no-hyponatraemia group). Univariate and multivariate logistic regression analyses identified different risk factors for thrombocytopenia and/or hyponatraemia (thrombocytopenia: Ccr and administration period; hyponatraemia: serum albumin; thrombocytopenia and hyponatraemia: administration period and serum albumin). WHAT IS NEW AND CONCLUSION: In conclusion, this study found no significant relationship between LZD-induced thrombocytopenia and hyponatraemia and identified some possible risk factors associated with onset of the two adverse events. These require further validation.

Multicenter surveillance of the epidemiology of gram-negative bacteremia in Japan.

This study investigated the epidemiology of adult patients with bacteremia caused by seven major gram-negative bacteria during a year at four university hospitals in Japan. Of the 438 cases included, Escherichia coli (247 patients) was the most frequently isolated pathogen, followed by Klebsiella species (89 patients), Enterobacter species (31 patients), Pseudomonas aeruginosa (29 patients), Bacteroides species (19 patients), Acinetobacter species (12 patients) and Stenotrophomonas maltophilia (11 patients). The overall, crude in-hospital mortality was 16.4%, ranging from 9.7% with Enterobacter species to 54.5% with S. maltophilia. Community- and hospital-acquired bacteremia accounted for 52.5% and 47.5%, respectively. Enterobacteriaceae were isolated from 93.0% of patients with community-acquired bacteremia, whereas non-fermenting bacteria were isolated from 21.6% of patients with hospital-acquired bacteremia. Of the 423 patients analyzed, 86.8% and 13.2% were monomicrobial and polymicrobial infections, respectively, and their in-hospital mortalities were 13.9% and 30.4%, respectively. Although carbapenem-resistant Enterobacteriaceae were not detected, extended-spectrum ß-lactamase (ESBL) production was seen in 24.3% of E. coli and 6.7% of Klebsiella species, respectively. E. coli producing ESBL showed high resistance rates to fluoroquinolones (approximately 90%), in contrast to non-producing-E. coli (approximately 21%). The susceptibilities to carbapenems and fluoroquinolones were approximately 80% for P. aeruginosa, whereas all Acinetobacter species were susceptible to these antibiotics. Bacteroides species showed 100% susceptibility to piperacillin/tazobactam and carbapenems, but only 47.4% were susceptible to clindamycin. Further studies, as well as continued surveillance, are required to determine the appropriate therapeutic strategy for gram-negative bacteremia.

Sub-minimum inhibitory concentrations of ceftazidime inhibit Pseudomonas aeruginosa biofilm formation.

Pseudomonas aeruginosa exhibits the biofilm mode of growth and causes chronic as well as acute infections in humans. Several reports have shown that the treatments with sub-minimum inhibitory concentrations (sub-MICs) of antimicrobial agents influence biofilm formation by P. aeruginosa. The antibiotic ceftazidime (CAZ) is used to treat P. aeruginosa infections, but few studies have examined the effects of ß-lactams on biofilm formation by P. aeruginosa. In this study, we investigated the role of sub-MICs of CAZ in the formation of P. aeruginosa biofilms. 1/4 × MIC CAZ reduced the biofilm volume of P. aeruginosa PAO1, as quantified by crystal violet staining. The formation of P. aeruginosa PAO1 biofilms treated with 1/4 × MIC CAZ were observed by confocal laser scanning microscopy. They were more heterogeneous than the PAO1 biofilms without CAZ treatment. Furthermore, sub-MICs of CAZ inhibited the twitching motility, which played an important role in mature biofilm formation. 1/4 × MIC CAZ also reduced the gene expressions of lecA, lecB, pel and psl, which mediate the adhesion and polysaccharide matrix synthesis of P. aeruginosa. These effects suggest that sub-MICs of CAZ may affect a number of stages of biofilm formation. Investigating the effects of sub-MIC antibiotics on targeted bacterial biofilm may lead to the development of future antibiotic treatment modalities.

A Retrospective Analysis of Risk Factors for Linezolid-Associated Hyponatremia in Japanese Patients.

Linezolid is an oxazolidinone antibiotic against Gram-positive bacteria. Although thrombocytopenia is a major adverse effect of linezolid, hyponatremia also often develops after linezolid administration. This study examined the frequency of hyponatremia that developed during linezolid treatment and identified its risk factors. In this retrospective, single-center, observational cohort study, 61 hospitalized patients treated with linezolid between January 2013 and January 2015 were analyzed. Hyponatremia was defined as a sodium level of ≤134 mEq/L for the duration of linezolid treatment. Its risk factors were identified via a logistic regression analysis. Hyponatremia occurred in 11 (18.0%) patients, and it was severe in a case (a sodium level of ≤128 mEq/L). Univariate and multiple logistic regression analyses identified the plasma C-reactive protein (CRP) level before the initial administration of linezolid and the concomitant use of a potassium-sparing diuretic as the independent variables associated with the development of hyponatremia. The odds ratios were 1.081 (95% confidence interval [CI]; 1.008-1.158) (p=0.028) and 11.017 (95% CI; 1.869-64.939) (p=0.008), respectively. Before linezolid treatment, the CRP levels of the hyponatremia group were significantly higher than those of the no-hyponatremia group (p<0.001). The frequency of hyponatremia development was significantly higher in the patients who received both the potassium-sparing diuretic and linezolid (p=0.016). These results suggest that the plasma sodium levels of patients with severe inflammation who are treated with linezolid and those of linezolid-treated patients co-administered a potassium-sparing diuretic should be continuously monitored.

Limited role of auxiliary endobronchial biopsy in the diagnosis of Japanese patients with sarcoidosis.

The diagnosis of sarcoidosis, a multisystem granulomatous disease of unknown etiology, is established when clinicoradiological findings are supported by histological evidence of non-caseating epithelioid cell granulomas. For pathological diagnosis, an endobronchial biopsy of normal-appearing bronchial mucosa in combination with transbronchial lung biopsy (TBLB) has been reported to be useful for sarcoidosis patients in Europe or the U.S. This is the first report assessing the utility of endobronchial biopsy for diagnosis of Japanese patients with sarcoidosis. Eighteen consecutive patients with strongly suspected sarcoidosis were evaluated by endobronchial biopsy of normal-appearing bronchial mucosa, together with TBLB and bronchoalveolar lavage. The TBLB specimens demonstrated non-caseating epithelioid cell granulomas in the lungs of 11 patients (61.1%), but not any specific findings in those of other 7 patients. In contrast, endobronchial biopsy specimens confirmed a diagnosis of sarcoidosis in only one patient that required steroid therapy for deterioration of pulmonary sarcoidosis. All 18 patients of this study, including 5 patients with pathological findings obtained from extrapulmonary sites, met the pathological or clinical diagnostic criteria. In conclusion, endobronchial biopsy of normal-appearing bronchial mucosa in combination with TBLB does not improve the diagnostic capacity for detecting sarcoidosis in Japanese patients, despite earlier reports. Thus, this method is of limited usefulness as a conventional diagnostic modality for Japanese patients with suspicious sarcoidosis. The present study also suggests the racial difference in the endobronchial involvement in pulmonary sarcoidosis.

Significant elevation of free itraconazole concentration at onset of adverse effects: A case report.

Free itraconazole and hydroxyitraconazole concentrations were markedly elevated despite almost no changes in total concentrations when itraconazole was discontinued due to adverse effects. Elevated free itraconazole concentration may have a causal relationship with the development of adverse effects.

Risk factors for disease-related deterioration following diagnostic bronchoalveolar lavage procedures in diffuse lung disease: a case-control study.

BACKGROUND: Although the risk factors for diagnostic bronchoalveolar lavage (BAL)-induced acute exacerbations in patients with idiopathic pulmonary fibrosis (IPF) have been previously reported, no study has assessed these in patients with non-IPF. We aimed to identify the risk factors for BAL-induced disease deterioration (BAL-DD) in all types of diffuse lung disease. METHODS: Patients with diffuse lung disease who underwent BAL at our hospital from April 2012 to November 2017 were retrospectively analyzed. The patient information, laboratory data, radiological findings, and BAL fluid analysis results in patients who developed BAL-DDs were compared with those in patients who did not. RESULTS: BAL-DDs occurred in 14 (3.3%) of the 429 patients included the study. The BAL-DD group had a significantly poorer performance status, higher C-reactive protein level, lower partial pressure of oxygen in the arterial blood at rest, greater proportion of desaturation on exertion and cases having followed a progressive clinical course before BAL, and more extensive consolidation and ground-glass opacity on chest high-resolution computed tomography (HRCT) than the non-BAL-DD group. A high total cell concentration and an increased number of eosinophils in the BAL fluid were more frequently found in patients with BAL-DD than in those without. CONCLUSIONS: Patients with decreased physical activity level, increased level of inflammatory markers, low oxygenation status, and extensive lung involvements on chest HRCT and following a progressive clinical course before BAL may be warned of the BAL-DD risk. Elevated eosinophil counts in the BAL fluid could be associated with the triggering of BAL-DDs.

A Pitfall of Treatment with Tosufloxacin for Pneumonia That Might Be Lung Tuberculosis.

Tosufloxacin, which is not used to treat Mycobacterium tuberculosis, is a fluoroquinolone recommended for pneumonia when the possibility of tuberculosis infection cannot be excluded. In the present case, symptoms and chest infiltrative shadow initially improved by tosufloxacin. Therefore, we regarded this patient as having general pneumonia and did not perform follow-up chest X-ray until the infiltrates had completely disappeared. However, a few weeks later, the symptoms and the infiltrates had worsened, so M. tuberculosis was isolated from the patient's sputum. This case suggests that patients suspected of having pulmonary tuberculosis should be monitored carefully, even if antibiotics without antituberculous activity are initially effective.

[Pulmonary metastasis of fibrosarcomatous variant of dermatofibrosarcoma protuberans: case report and review of literature].

A 63-year-old man had undergone excision of a growing mass with a wide margin in the left supraclavicular fossa. A diagnosis of fibrosarcomatous variant of dermatofibrosarcoma protuberans (DFSP-FS) was made. Three years later, an abnormal chest shadow was detected on a medical checkup. Chest computed tomography showed a heterogeneously-enhanced 2-cm coin lesion with a distinct border in the right lower lobe and a 3-mm nodule in the left lower lobe. Transbronchial lung biopsy specimens from the right lung revealed a DFSP pattern. We then performed right basal segmentectomy and partial resection of the left lower lobe. DFSP is a relatively rare skin tumor that is considered to be intermediate malignancy. It frequently recurs locally but rarely has systemic metastasis. However, DFSP-FS, a subtype of DFSP, has an increased likelihood of systemic metastasis. The lung is the most common site of metastasis of DFSP-FS. DFSP-FS sometimes recurs even a long time after excision. Therefore, long-term follow-up, including chest X-ray and CT are important in DFSP-FS patients.

The prophylactic effectiveness of various antifungal agents against the progression of trichosporonosis fungemia to disseminated disease in a neutropenic mouse model.

Neutropenic mice with latent trichosporonemia were given various antifungal agents (amphotericin B, fluconazole, itraconazole) or saline to determine which antifungal agent could be useful for prophylaxis. The 3-week-survival rate was 80% in the fluconazole group, 50% in the amphotericin B group, 45% in the itraconazole group, and 30% in the saline group. Compared with the other antifungal agents, fluconazole offered superior prophylaxis against the progression of trichosporonosis fungemia to disseminated disease (P<0.05). These results suggest that clinical studies are warranted to investigate fluconazole prophylaxis of trichosporonosis progression in neutropenic patients, such as people receiving chemotherapy and patients who have received solid organ transplants.

[A case of bronchiolitis possibly associated with inhalation of hard metal].

A 36-year-old man, a worker exposed to tungsten and cobalt compounds, was admitted because of chest bilateral micronodular shadow with chronic cough and sputum. Chronic sinusitis, mild hypoxemia, obstructive respiratory impairment and chest radiological findings fulfilled the Japanese diagnostic criteria for diffuse panbronchiolitis, while atypical bronchoalveolar lavage fluid and pathological findings were seen. The surgical lung biopsy specimens showed patchy centrilobular inflammatory change with monocytic infiltrations and particulate deposition inside the area of bronchiolitis, but neither tungsten nor cobalt was found. Treatment with a macrolide antibiotic had no effect on the patient's symptoms, hypoxemia and lung function, suggesting bronchiolitis associated with inhalation of hard metal.

[Pulmonary lymphomatoid granulomatosis radiologically mimicking interstitial pneumonia].

We report a rare case of pulmonary lymphomatoid granulomatosis radiologically mimicking interstitial pneumonia. A 57-year-old man was admitted to our hospital because of chest bilateral reticular shadow with sustained cough and breathlessness for 10 years. Chest CT scans showed multiple ground-glass opacities, traction bronchiectasis and cystic change in both lungs, in addition to hilar and mediastinal lymphadenopathy. A histopathologically diagnosis of pulmonary lymphomatoid granulomatosis (angiocentric immunoproliferative lesion, grade 1) was made by thoracoscopic lung biopsy. In this case, serological and immunohistochemical analyses did not show Epstein-Barr virus infection. No clinical or radiological deterioration has been observed thereafter despite no medication.

[A case of Sweet's syndrome with a variety of chest radiological findings].

We report a rare case of Sweet's syndrome (acute febrile neutrophilic dermatosis) with a variety of chest radiological findings. A 73-year-old man, who had been treated with corticosteroid for Sweet's syndrome for 2 years, was admitted to our hospital because of pyrexia with a infiltrative chest shadow. Chest CT scans showed consolidation and ground-glass opacities with air-bronchogram in the right lower lobe. Treatment with antibiotics seemed to be effective but there was no improvement of chest shadows. Simultaneously with his pyrexia, diffuse centrilobular-micronodular shadows and a mass-like shadow appeared on chest CT after 2 months and after the next 2 months, respectively. Bronchoalveolar lavage fluid contained increased neutrophils but not any infectious pathogen. Transbronchial lung biopsy specimens revealed chronic interstitial infiltrate with alveolar wall thickening and neutrophil accumulation in the airspace. A diagnosis of pulmonary involvement in a patient with Sweet's syndrome was finally made and he was successfully treated with corticosteroid.

Sensitive and selective quantification of total and free itraconazole and hydroxyitraconazole in human plasma using ultra-performance liquid chromatography coupled to tandem mass spectrometry.

OBJECTIVES: Protein-free (unbound) drug concentrations have been reported to be better biomarker of pharmacodynamics compared with total drug concentrations. In this study, we developed and validated an assay for the quantification of total and free itraconazole and hydroxyitraconazole, a main metabolite with antifungal activity, in human plasma using ultra-performance liquid chromatography coupled to tandem mass spectrometry (UPLC-MS/MS). DESIGN & METHODS: Plasma sample was ultra-filtrated for the measurement of free itraconazole and hydroxyitraconazole concentrations. The samples were prepared by solid phase extraction, and then subject to UPLC-MS/MS quantification. RESULTS: The assay fulfilled the requirements of the US Food and Drug Administration (FDA) and the European Medicines Agency (EMA) guidelines for assay validation, with a lower limit of quantification of 10ng/mL for total itraconazole and hydroxyitraconazole, and 0.1 and 0.5ng/mL for free itraconazole and hydroxyitraconazole, respectively. Recovery rates of total itraconazole and hydroxyitraconazole from whole plasma ranged from 53.3% to 64.0%, and recovery rates of free itraconazole and hydroxyitraconazole from ultrafiltrated plasma ranged from 81.6% to 98.7%. Matrix effect varied between 79.1% and 109.4% for total itraconazole and hydroxyitraconazole, and between 81.3% and 99.7% for free itraconazole and hydroxyitraconazole. The assay was successfully applied to therapeutic drug monitoring of itraconazole in three patients with chronic progressive pulmonary aspergillosis or invasive pulmonary aspergillosis. Plasma free hydroxyitraconazole concentrations were 8.1-, 23.3-, and 51.1-fold higher than plasma free itraconazole concentrations in the three patients. CONCLUSIONS: A method for sensitive and selective quantification of plasma total and free itraconazole and hydroxyitraconazole concentrations was developed using UPLC-MS/MS. Free hydroxyitraconazole concentration may be most important in therapeutic drug monitoring of itraconazole.

Association of sustained high plasma trough concentration of voriconazole with the incidence of hepatotoxicity.

BACKGROUND: Therapeutic drug monitoring (TDM) of voriconazole is important to optimize efficacy and to minimize toxicity and intolerance. In this study, we evaluated the effect of sustained high plasma trough concentration of voriconazole on the incidence of hepatotoxicity in hospitalized Japanese patients. METHODS: Thirty-nine patients were divided into 3 groups according to trough concentrations in two consecutive TDMs: <4 µg/ml in the first TDM (group A, n=25), >4 µg/ml in the first and <4 µg/ml in the second TDM (group B, n=8), and >4 µg/ml in both first and second TDMs (group C, n=6). RESULTS: Incidences of hepatotoxicity in groups A, B and C were 16.0, 25.0 and 83.3%, and significant differences were observed between groups A and C and groups B and C. Multiple logistic regression analysis identified the classification into groups A, B and C as an independent variable of hepatotoxicity. CONCLUSIONS: These results suggest that sustained high trough concentration of voriconazole may increase the risk of hepatotoxicity, and decreasing trough concentration to <4 µg/ml by dose adjustment after the initial TDM may reduce the incidence of hepatotoxicity in patients treated with voriconazole.

Inhibitory effects of pitavastatin on fibrogenic mediator production by human lung fibroblasts.

AIMS: Idiopathic pulmonary fibrosis continues to be a devastating clinical disorder for which there are few therapeutic options, and the pathogenesis of this disease remains largely unknown. Statins are inhibitors of 3-hydroxy-3-methylglutaryl-coenzyme A reductase in cholesterol biosynthesis, and they have been reported to exert pleiotropic effects on the cellular signaling involved in tissue inflammation and in organ fibrosis/remodeling. We examined the preventive effects of statins on fibrogenic mediator expression and production in normal human lung fibroblasts (NHLF). MAIN METHODS: NHLF were pretreated with 100nM pitavastatin or medium alone (control), and were then stimulated with transforming growth factor-ß1 (TGF-ß1). mRNA expression and protein secretion of several mediators from cells were analyzed by real-time polymerase chain reaction, enzyme-linked immunosorbent assay or multiplex assay. KEY FINDINGS: TGF-ß1-induced expression or production of mediators, such as collagen-1, vascular endothelial growth factor and chemokine C-X-C motif ligand 8, in NHLF pretreated with pitavastatin was significantly suppressed with inhibition of Smad-3 phosphorylation, as compared to untreated controls. In addition, the inhibitory effects of pitavastatin were negated by addition of mevalonate. SIGNIFICANCE: Pitavastatin appeared to inhibit TGF-ß1-induced fibrogenic mediator production from lung fibroblasts via the mevalonic cascade. Although further evaluation of the signaling pathways for these phenomena is necessary, our results suggest the potential benefits of pitavastatin.

Invasive pulmonary aspergillosis with hematological malignancy caused by Aspergillus terreus and in vitro susceptibility of A. terreus isolate to micafungin.

A 35-year-old man developed invasive pulmonary aspergillosis (IPA) with severe neutropenia after umbilical cord stem cell transplantation for chronic myelogenous leukemia. Filamentous fungus isolated from his sputum was identified as Aspergillus terreus. Despite systemic amphotericin B (AMPH) administration, IPA progressed. However, intravenous administration of micafungin (MCFG) and oral itraconazole improved clinical data and symptoms, although he later died of massive hemoptysis. Examination of the in vitro susceptibility of this A. terreus isolate to MCFG revealed a good minimum inhibitory concentration and good time-kill assay results compared to AMPH. Thus, MCFG might be useful for IPA caused by A. terreus.

A case of empyema caused by Edwardsiella tarda.

In December 2003, a 57-year-old-man was diagnosed as having a hepatic tumor for which he had a hepatectomy. On pathology, the hepatic tumor biopsy specimen was diagnosed as malignant lymphoma. In February 2005, the patient was referred to our hospital because of fever and chest pain. A right pleural effusion was seen on chest X-ray. Microscopic examination of the stained pleural fluid revealed many neutrophils and Gram-negative rods, and Edwardsiella tarda was cultured from the pleural effusion fluid. These findings were consistent with an empyema caused by E. tarda. Therefore, we treated the patient with panipenem/betamipron and thoracic drainage. In this paper, we describe this rare case of empyema caused by E. tarda infection.