Kenji Ohnishi

Severe murine typhus with shock and acute respiratory failure in a Japanese traveler after returning from Thailand.

We treated a case of severe murine typhus in a Japanese traveler after returning from Thailand. Although the disease is typically self-limited or mild, the patient showed shock and multiple organ failure including acute respiratory distress syndrome. Then the patient fully recovered following intensive care and administration of antirickettsial medicines.

Generation of a Neutralizing Human Monoclonal Antibody Fab Fragment to Surface Antigen 1 of Toxoplasma gondii Tachyzoites

ABSTRACT A combinatorial immunoglobulin gene library was constructed from lymphocytes in peripheral blood of a patient with toxoplasmosis and screened for production of human monoclonal antibody Fab fragments to recombinant surface antigen 1 (SAG1) of Toxoplasma gondii. Two Fab clones, Tox203 and Tox1403, which consisted of a common heavy chain and different light chains, showed positive staining on the entire surface of tachyzoites in confocal microscopy. Sequence analysis of the heavy-chain gene revealed that the closest germ line V segments were VH3-23. The germ line D segment was D1-7, and the closest germ line J segment was JH4. In the light-chain genes, the closest germ line V segment was Vκ1-17 with the Jκ1 or Jκ4 segments. The dissociation constants of these Fab fragments with recombinant SAG1 were 3.09 × 10−9 M for Tox203 and 2.01 × 10−8 M for Tox1403, indicating that the affinity of Tox203 was 7 times higher than that of Tox1403. Preincubation of T. gondii tachyzoites with Tox203 significantly inhibited their attachment to cultured MDBK cells. Passive immunization of mice with Tox203 also significantly reduced mortality after challenge with T. gondii tachyzoites. This is the first report of bacterial expression of human monoclonal antibody Fab fragments to SAG1 of T. gondii. These results also demonstrate that human Fab fragments to SAG1 might be applicable for immunoprophylaxis of toxoplasmosis.

Treatment of symptomatic amebic colitis in human immunodeficiency virus-infected persons.

While most Entamoeba histolytica appearing in male homosexuals infected with human immunodeficiency virus (HIV) is considered non-invasive in Western countries, and treatment of amebiasis in these persons has received very little attention, in Japan some male homosexual amebiasis patients infected with HIV complain of symptoms attributable to E. histolytica infection. We investigated whether symptomatic E histolytica amebic colitis in HIV-infected persons requires higher doses or longer duration of antiamebic drug therapy than in non HIV-infected patients. Four symptomatic amebic colitis patients infected with HIV-1, three of them severely immunocompromised, with CD4 cell counts <200/mm(3), were treated with oral metronidazole: 1500 mg a day for 10 days in 2 patients, 1000 mg a day for 10 days in 1 patient, and 1000 mg a day for 6 days and then 750 mg for 4 days in 1 patient, and good therapeutic results with no side effects were obtained. This indicates that symptomatic amebic colitis in HIV-infected persons can be successfully treated with metronidazole at the same dose and duration of treatment used in non-HIV-infected persons.

Subjective adverse reactions to metronidazole in patients with amebiasis.

Subjective adverse reactions to metronidazole were analyzed in 111 patients with amebiasis. Metronidazole was administered to 36 patients at a daily dose of 2250 mg and 75 patients at daily doses lower than 2250 mg. The reactions reported included nausea without vomiting in 11 (9.9%) patients, nausea with vomiting in 2 (1.8%), dysgeusia in 2 (1.8%), diarrhea in 1 (0.9%), headache in 1 (0.9%), numbness in 1 (0.9%), dizziness in 1 (0.9%), urticaria in 1 (0.9%), exanthema in 1 (0.9%), and discomfort in 1 (0.9%). Nausea was reported by 28% (10/36) of the patients receiving metronidazole at a daily dose of 2250 mg and 4% (3/75) of the patients receiving lower daily doses. The duration of the metronidazole administration in days was not associated with the appearance of nausea. No life-threatening adverse reactions were identified, and good clinical therapeutic effects were observed in 96% (107/111) of the patients. While metronidazole appears to be a safe anti-protozoal agent for patients with amebiasis, our results indicate that a daily metronidazole dose of 2250 mg is excessive for amebiasis, as it often induces nausea.

Streptococcal toxic shock syndrome secondary to group A Streptococcus vaginitis.

Streptococcal toxic shock syndrome (TSS) is a systemic illness usually caused in the setting of infection by group A Streptococcus (GAS). The primary infections are often invasive infections of the respiratory tract or necrotizing infections of the skin and soft tissue, but some infections occur without relevant focus. GAS vaginitis is a rare condition among adult women and is accordingly thought to be uncommon as a cause of streptococcal TSS. Here we report the cases of two postmenopausal women with streptococcal TSS secondary to GAS vaginitis, one aged 55 and one aged 60. Both came to our emergency department with complaints or symptoms of abdominal pain, fever, hypotension, and multi-organ failure. In both cases, the relevant factor associated with streptococcal infection was a recent episode of GAS vaginitis. Both underwent fluid management and 14 days of antibiotic treatment and fully recovered without complications. Vaginitis was likely to be the primary infectious trigger of TSS in these two cases. Intrauterine device insertion, endometrial biopsy, and post-partum state have all been previously reported in TSS patients, and the female genital tract has been described as a portal of entry. GAS vaginitis warrants appropriate treatment as it may progress to severe systemic infection as described.

Dengue-associated hemophagocytic syndrome in a Japanese traveler: a case report.

Hemophagocytic syndrome (HPS) can develop as a complication of dengue in rare cases, but its relationship with dengue is not well known. We report a case of dengue-associated HPS with liver involvement and coagulopathy. The patient, a Japanese female traveler who had recently returned from Thailand, had severe complications of dengue infection, but she recovered fully with symptomatic treatment.

Leptospirosis in a Japanese urban area: A case report and literature review

Leptospirosis is not a major disease in urban areas of Japan. We describe a 49-year-old man with leptospirosis, who lived in an urban area and had no history of living in endemic area of leptospirosis. As he worked at a fish market infested with rats, he was suspected of having contracted leptospirosis and received antimicrobial agent treatment. Serum and urinary tests confirmed the diagnosis of leptospirosis. Although it took six days from the onset until treatment initiation, the patient improved in response to receiving ceftriaxone for seven days. Analyzing past reports of Japanese patients with leptospirosis who had no history of overseas travel, we identified 90 patients with courses similar to that of our patient, and the period from onset to treatment initiation was about six days on average (described in 46 cases). Health care providers as well as patients need to recognize that even people with no history of being in an endemic area of leptospirosis may still be at risk of developing this disease depending on occupations and activities.

Therapeutic Effect of Fluoroquinolones against Shigellosis Patients Coinfected with Giardia lamblia

This study examined whether coinfection of shigellosis patients withGiardia lamblia had any influence on the bacterial therapeutic effect of fluoroquinolones. Five shigellosis patients with a coinfection withG. lamblia and 15 control patients with shigellosis only were treated with standard doses of fluoroquinolones. The mean day to the disappearance of theShigella spp. in the study patients was 1.6 days after the start of drug administration, and 1.8 days in the control shigellosis patients. The therapeutic efficacy of treatment by fluoroquinolones for shigellosis infection was not influenced by coinfection withG. lamblia.