Rhodococcus equi infections in immunocompetent hosts: case report and review.

Rhodococcus equi is an unusual cause of infection in humans. Infection in immunocompetent patients is extremely rare-only 19 cases in immunocompetent hosts have been reported. Localized infections represent nearly 50% of reported cases. Pulmonary infections account for only 42% of infections in immunocompetent hosts, compared with 84% of infections in immunocompromised hosts. The mortality rate among immunocompetent patients is approximately 11%, compared with rates of 50%-55% among human immunodeficiency virus (HIV)-infected patients and 20%-25% among non-HIV-infected immunocompromised patients. Treatment of infections in immunocompetent hosts depends on the site of infection. Serious infections need to be treated with combinations of parenteral antibiotics, followed by combinations of oral antibiotics. Surgical treatment is necessary for certain types of local infections. We report a pulmonary infection due to R. equi in an immunocompetent patient, and we review all reported cases of R. equi infection in immunocompetent hosts.     

Fulminant Cytomegalovirus Myocarditis in an Immunocompetent Host: Resolution with Oral Valganciclovir

We report a case of fulminant myocarditis after a primary cytomegalovirus infection, in a previously healthy 72-year-old woman. The infection underwent clinical and immunologic resolution consequent to treatment with oral valganciclovir. In an immunocompetent host, the primary cytomegalovirus infection is usually asymptomatic or manifests itself as a heterophile-negative mononucleosis-like syndrome. Cytomegalovirus myocarditis is uncommon in immunocompetent patients. After presenting our case, we review the literature on cytomegalovirus myocarditis in immunocompetent individuals.     

低剂量隐孢子虫感染正常和免疫抑制小鼠的效应研究

目的 研究低剂量隐孢子虫感染正常和免疫抑制小鼠的相关效应指标，了解低剂量隐孢子虫感染的风险及相关效应。方法 采用地塞米松作为免疫抑制剂，建立小鼠的免疫抑制模型，再给予不同剂量的隐孢子虫攻击，比较不同的效应指标。结果 免疫抑制组小鼠脾重指数、胸腺指数与对照组比较差异有显著性（P〈0．05）。免疫抑制小鼠IgG、IgM含量与对照组比较差异亦有显著性（P〈0．05）。免疫抑制情况下粪便白细胞计数与相应的对照组比较，50、100、500个卵囊剂量组之间差异均有显著性（P〈0．05）。免疫抑制组与对照组的腹泻发生率，500个剂量组差异有显著性（P〈0．05）。将剂量对数和腹泻发生率作回归分析，免疫抑制和对照组的剂量对数和腹泻发生率呈现较好的线性关系（P〈0．05）。结论 较低剂量（10～50个卵囊）的隐孢子虫即可引起小鼠感染并出现腹泻症状，且出现粪便白细胞排出增加。在较低剂量条件下，免疫抑制小鼠粪便白细胞、腹泻发生率均高于相应的对照组，且潜伏期缩短，免疫抑制小鼠感染低剂量隐孢子虫发病的风险更大。     

Portal hypertension caused by acute cytomegalovirus infection with liver involvement in an immunocompetent patient

Primary infection by cytomegalovirus in immunocompetent patients is usually unapparent. We report a case of severe acute cytomegalovirus infection in a young immunocompetent male with pulmonary and hepatic involvement and portal hypertension who recovered without specific antiviral therapy with complete resolution of sonographic signs of portal hypertension after 6 months.     

Fatal human herpesvirus 6-associated multifocal meningoencephalitis in an adult female patient

Human herpesvirus 6 (HHV 6) is a known cause of central nervous system infection in immunocompromised patients. Less is known about the clinical course of HHV 6 encephalitis in immunocompetent patients. We report a case of meningoencephalitis in a 42-y-old immunocompetent patient associated with HHV 6 infection.     

Fever of unknown origin (FUO) in an immunocompetent adult due to cytomegalovirus (CMV) with polyclonal gammopathy

Fever of unknown origin (FUO) may be due to infection, malignancy, collagen vascular/inflammatory disorders, or other causes. Cytomegalovirus (CMV) infection is a rare cause of FUO in immunocompetent adults. We present a case of FUO due to CMV in an immunocompetent adult with polyclonal gammopathy on serum protein electrophoresis (SPEP).     

Chronic infection and reactivation in a pulmonary challenge model of histoplasmosis

Reactivation may be a mechanism for the development of histoplasmosis in AIDS. In this study, histoplasmosis was reactivated by the depletion of CD4 and CD8 lymphocytes in mice. CD4 and/or CD8 depletion beginning 1 month after intratracheal infection and continuing for 2 months caused reactivation with a 2.1 log/g increase in the lungs and a 1.5 log increase in the spleen of B6C3F1 mice. Because control animals showed persistent infection, a subsequent experiment sought to determine the long-term outcome in competent mice. Twelve of 32 immunocompetent mice died at weeks 26-52 of infection, and 4 survivors appeared to be clinically ill; all ill mice had high fungus burdens, whereas cultures were sterile in the healthy mice. Eight of the surviving healthy-appearing mice underwent autopsy 2 years after infection, and cultures were sterile. Thus, 16 of 32 immunocompetent mice exhibited progressive infection. CD4 and/or CD8 depletion exacerbated infection, but a chronic progressive and ultimately fatal infection occurred in half the immunocompetent mice.     

An unexpected pulmonary infection in a patient with gastric tube interposition, reconstruction of the hypopharynx and gastric-hypopharyngeal anastomosis

Pulmonary infection by Nocardia spp. has been recognized the last decades. Nocardia is an opportunistic pathogen in immunocompromised individuals; nevertheless, it has been recognized as an uncommon pathogen in immunocompetent patients. We report a case of pulmonary infection by Nocardia asteroides in an immunocompetent host who had a history of sulfate acid aspiration, followed by gastric tube interposition, reconstruction of the hypopharynx and gastric-hypopharyngial anastomosis.     

Disseminated cryptococcosis in an immunocompetent child

Cryptococcosis is caused by cryptococcus neoformans. Immunosuppression is a predisposing factor for the development of cryptococcosis. However, reports exist that cryptococcus neoformans can cause infection in immunocompetent hosts. We report a case of disseminated cryptococcosis in a 7.5-year-old immunocompetent child.     

Comparison of leukocytes obtained from the intestinal lumen of Giardia-infected immunocompetent mice and nude mice

Previous studies have suggested that Giardia infections are cleared immunologically, but have not defined the mechanism of clearance. The aim of the present work was to compare subpopulations of leukocytes harvested from the intestinal lumen of immunocompetent BALB/c mice, which clear Giardia muris infection rapidly, with those of immunodeficient nude mice, which become chronically infected with Giardia muris. Leukocytes were obtained from the intestinal lumen of Giardia-infected mice, and subpopulations of these cells were quantified after immunofluorescent staining with monoclonal antibodies. Identical numbers of leukocytes were harvested from the intestinal lumen of Giardia-infected immunocompetent mice and nude mice, but the number of these leukocytes bearing the T-lymphocyte antigen Thy-1.2 was smaller in nude mice than in immunocompetent mice. In contrast, no striking differences were observed between the numbers of luminal cytotoxic/suppressor T lymphocytes or macrophages in Giardia-infected nude versus immunocompetent mice. The findings suggest that clearance of Giardia muris infection is not mediated by cytotoxic T lymphocytes or macrophages. Subsequently, T lymphocytes and T-lymphocyte subsets were quantified in cell suspensions prepared from Peyer's patches of immunocompetent BALB/c mice and nude mice. It was found that nude mice have a profound deficiency of Peyer's patch helper/inducer T lymphocytes. This deficiency may account for the inability of nude mice to clear Giardia muris infection at a normal rate.     

隐孢子虫动物模型的建立

本文通过饮水给予免疫抑制药和用人源隐孢子虫卵囊感染ＮＩＨ小鼠，建立了隐孢子虫感染小鼠模型。实验结果显示：免疫功能抑制组比正常组易感，两者感染度有显著性差异（Ｐ＜０．０５）。通过动物实验进一步证明免疫功能正常宿主感染隐孢子虫为自限性感染，免疫功能低下或缺陷者感染隐孢子虫可引起严重腹泻甚至死亡。     

Cholestasis,ascites and pancytopenia in an immunocompetent adult with severe cytomegalovirus hepatitis

Human cytomegalovirus (CMV) is a herpesvirus, which establishes lifelong latency after primary infection and leads to severe disease in immunocompromised patients. However, CMV infection in immunocompetent patients is usually asymptomatic and severe organ damage is rarely reported. We report a case of severe CMV hepatitis in an immunocompetent patient presenting with cholestasis, portal hypertension-related ascites and pancytopenia. The patient was asymptomatic with normal liver function and negative CMV DNA after two weeks of antiviral therapy. This case is an example of a common infection with an uncommon presentation, and suggests that testing for CMV should be carried out, even in patients with normal immune status, presenting with severe liver damage or cholestasis.     

Antibody maturation and viremia after primary cytomegalovirus infection, in immunocompetent patients and kidney-transplant patients

To investigate antibody maturation and serum levels of cytomegalovirus (CMV) DNA after primary CMV infection, we studied 51 immunocompetent and 27 kidney-transplant patients. Compared with the immunocompetent patients, the transplant patients had significantly more-prolonged and -variable antibody maturation, clearly longer durations of viremia, and higher levels of CMV DNA; however, antibody maturation continued for >1 year even in immunocompetent patients. Long-term ganciclovir prophylaxis in the transplant patients was associated with either delayed immunoglobulin-G seroconversion, inhibition of antibody maturation (n=2), or immunoglobulin-class switching (n=1). In conclusion, antibody maturation continues in immunocompetent patients for a period longer than previously had been thought and is significantly delayed or even inhibited in kidney-transplant patients.     

Disseminated intravascular coagulation due to cytomegalovirus infection in an immunocompetent adult treated with plasma exchange

We report the case of an immunocompetent woman who developed disseminated intravascular coagulation (DIC) due to acute cytomegalovirus (CMV) infection and was successfully treated with plasma exchange. Extensive investigations revealed no other cause for her DIC, and she did not have any recurrence after more than 1 year of follow up. Clinically evident DIC due to CMV infection is most common in immunosuppressed patients. The one previously reported immunocompetent patient with DIC due to acute CMV infection died from the illness despite traditional supportive measures. Plasma exchange is a novel therapy that should be considered in this situation.     

Cytomegalovirus (CMV)-related cutaneous necrotizing vasculitis: case report and literature review

Cytomegalovirus (CMV) infection is usually asymptomatic in immunocompetent patients. A mononucleosis-like syndrome may develop in some patients. Various organ involvements (eg: encephalitis, meningitis, retinitis, myocarditis, pneumonia, hepatitis, enterocolitis, neuritis), which rarely occur in immunocompetent patients, have also been reported. Cutaneous necrotizing vasculitis caused by CMV infection has been reported very rarely in the literature. Here, a case with a very rare clinical form of CMV infection, presenting with persistent fever and livedo reticularis on the extremities and cutaneous necrotizing vasculitis of the toes, is described, and the relevant literature is reviewed. This case report aims to highlight the possibility of CMV infection to be a cause of cutaneous necrotizing vasculitis.     

Self-limited colitis during the course of rubella and cytomegalovirus infection in an immunocompetent adult

We report a case of self-limited colitis in cytomegalovirus (CMV) infection in an immunocompetent adult. A 22-year-old man developed a high fever and diarrhea. Laboratory data revealed an increased number of lymphocytes and liver damage. Enzyme immunoassays for anti-virus antibodies revealed that the patient was recently infected with CMV and rubella. Colonoscopy revealed severe erosive and edematous mucosa that resembled ulcerative colitis (UC). The symptoms, laboratory data and colonoscopic findings improved without any medical treatment. This case indicates that UC-like self-limited colitis can occur in an immunocompetent individual during the course of CMV infection.     

Pulmonary embolism and portal vein thrombosis in an immunocompetent adolescent with acute cytomegalovirus hepatitis

Cytomegalovirus infection is usually asymptomatic or resembles infectious mononucleosis with fever, pharyngitis, arthralgias, lymphadenopathy, and atypical lymphocytosis. Even though primary CMV infection is usually self-limited in healthy individuals, significant complications can develop in immunocompromised patients. Venous or arterial thromboembolic phenomena are uncommon, yet very serious complications of CMV infection. Most published reports describe immunosupressed patients after organ transplantation or in the presence of HIV co-infection. However, thrombotic events in CMV infected immunocompetent individuals may occur. We describe the case of an immunocompetent adolescent with acute cytomegalovirus hepatitis that was complicated with pulmonary embolism and portal vein thrombosis. To our knowledge, this is the first reported case in which these two thrombotic phenomena occurred simultaneously in an adolescent with no obvious predisposing factors for thrombosis in the setting of an acute CMV infection.     

Necrotizing periorbital Fusarium infection--an emerging pathogen in immunocompetent individuals

Fungal infections of the skin and deeper tissues of the periorbital region are quite rare. We report a case of a localized, deep periorbital necrotizing Fusarium infection in an otherwise healthy, elderly lady. Since the clinical features and histopathological findings of Fusarium infection are by no means characteristic, the definitive diagnosis was achieved with the help of microbiological examination of cultured organisms. A combined medical and surgical therapy led to adequate control of infection. To conclude, localized, deep periorbital necrotizing soft tissue infection by Fusarium in an immunocompetent lady is not reported in literature. One should have a high index of suspicion for emerging fungal pathogens in the differential diagnosis of necrotizing orbital or adnexal conditions, even in an immunocompetent patient. The histologic findings of septate, branching hyphae and vascular invasion cannot distinguish Fusarium species from various other moulds such as Aspergillus species; microbiologic studies are essential for confirming the diagnosis.     

Cladophialophora bantiana brain abscess in an immunocompetent patient

Cladophialophora bantiana is a dematiaceous mold with a predilection for causing central nervous system infection, particularly in normal hosts. A case involving a 79-year-old immunocompetent woman who presented with left-sided weakness and a ring-enhancing brain lesion is reported. She underwent surgical excision, which revealed a brain abscess due to C bantiana. The patient was treated with liposomal amphotericin B for several weeks, then switched to voriconazole and flucytosine, but eventually succumbed to the infection. Therapy is not standardized for this rare mycosis, and mortality remains high, even in immunocompetent patients. Additional studies to understand the pathogenesis of this infection and to improve outcomes are needed.