Yoshitaka Wakabayashi

Propionimicrobium lymphophilum and Actinotignum schaalii bacteraemia: a case report

Propionimicrobium lymphophilum is an anaerobic Gram-positive bacillus that exists in human skin and urinary tract. The pathogenicity is, however, not well known. Only two cases of urinary tract infection have been described recently. In the case presented here, the bacterium was isolated, concomitant with Actinotignum schaalii, from blood culture of a patient with fever and difficulty of urination. The bacteria were identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and 16S rRNA sequencing. The case was successfully treated with ampicillin/sulbactam.

Scedosporium prolificans Endocarditis: Case Report and Literature Review.

Scedosporium prolificans, a hyaline filamentous fungus, is widely distributed in the environment and is currently an emerging human pathogen, especially among immunocompromised patients. However, S. prolificans endocarditis is rare. We herein report a case of S. prolificans endocarditis in a 64-year-old patient with breast cancer in complete remission for 30 years after chemotherapy and radiation treatment who was not cured. Susceptibility testing showed resistance to all antifungal drugs, except echinocandin. A review of the literature revealed 10 cases of S. prolificans endocarditis; of these, only one involved an immunocompetent host with no risk factors and only two patients survived. In order to improve the mortality rate, it is necessary to establish rapid diagnostic methods and efficient therapeutic approaches.

A pathologically proven case of adult-onset HIV-related lymphocytic interstitial pneumonia with acute exacerbation treated with steroid and antiretroviral therapy

Lymphocytic interstitial pneumonia (LIP) is a rare opportunistic illness in human immunodeficiency virus (HIV)-infected adults, although it is relatively common among HIV-infected children. Most adult cases have been reported in African and Afro-Caribbean patients and few cases have been reported from Asia. Acute exacerbation of HIV-related LIP has not been well described. Here we report a pathologically proven case of acute exacerbation of adult-onset HIV-related LIP. The patient was an African immigrant living in Japan who presented with chronic dyspnea and diffuse bilateral pulmonary infiltrates. His clinical, radiological, and pathological findings were consistent with those of LIP. After a diagnostic surgical lung biopsy, his hypoxemia and pulmonary infiltrates exacerbated rapidly over a few days, although his condition had not progressed during the previous year. LIP may be an important differential diagnosis among adult patients in Asian countries, especially patients of non-Asian ethnicity.

Inhibition of osteoblast differentiation by ritonavir

Osteoporosis is one of the chronic complications seen in human immunodeficiency virus (HIV)-infected patients, and affects patients at high prevalence. The causes of osteoporosis in HIV-infected patients are multiple, and include chronic HIV infection, living habits such as smoking and alcohol consumption, and antiretroviral drug use. Among antiretroviral drugs, protease inhibitors have been reported to be associated with osteoporosis. However, it remains to be determined how anti-HIV drugs affect osteoblast differentiation. In the current study, MC3T3-E1 cells, a mouse osteoblastic cell line, were cultured in osteoblast differentiation medium with or without different protease inhibitors (ritonavir, lopinavir, darunavir or atazanavir), and alkaline phosphatase (ALP) activity and the expression of Runt-related transcription factor 2 (Runx2) were analyzed. The ALP activity in MC3T3-E1 cells cultured with ritonavir was significantly reduced compared with that in cells in only osteoblast inducer reagent, indicating that ritonavir inhibited osteoblast differentiation. Meanwhile, ALP activity was not reduced in cells cultured with any of the other inhibitors. In addition, ritonavir inhibited the expression of Runx2, a key regulator of osteoblast differentiation, in the early period of osteoblast differentiation. To the best of our knowledge, this is the first study to demonstrate that ritonavir inhibits osteoblast differentiation in vitro. The present findings may explain the mechanism of osteopenia induced by combination antiretroviral therapy involving protease inhibitors.