Septic shock due to toxoplasmosis in patients infected with the human immunodeficiency virus

The Biochemical and Clinical Perspectives of Lactate Dehydrogenase: An Enzyme of Active Metabolism

BACKGROUND

Lactate dehydrogenase (LDH) is a group of oxidoreductase isoenzymes catalyzing the reversible reaction between pyruvate and lactate. The five isoforms of this enzyme, formed from two subunits, vary in isoelectric points and these isoforms have different substrate affinity, inhibition constants and electrophoretic mobility. These diverse biochemical properties play a key role in its cellular, tissue and organ specificity. Though LDH is predominantly present in the cytoplasm, it has a multi-organellar location as well.

OBJECTIVE

The primary objective of this review article is to provide an update in parallel, the previous and recent biochemical views and its clinical significance in different diseases.

METHODS

With the help of certain inhibitors, its active site three-dimensional view, reactions mechanisms and metabolic pathways have been sorted out to a greater extent. Overexpression of LDH in different cancers plays a principal role in anaerobic cellular metabolism, hence several inhibitors have been designed to employ as novel anticancer agents.

DISCUSSION

LDH performs a very important role in overall body metabolism and some signals can induce isoenzyme switching under certain circumstances, ensuring that the tissues consistently maintain adequate ATP supply. This enzyme also experiences some posttranslational modifications, to have diversified metabolic roles. Different toxicological and pathological complications damage various organs, which ultimately result in leakage of this enzyme in serum. Hence, unusual LDH isoform level in serum serves as a significant biomarker of different diseases.

CONCLUSION

LDH is an important diagnostic biomarker for some common diseases like cancer, thyroid disorders, tuberculosis, etc. In general, LDH plays a key role in the clinical diagnosis of various common and rare diseases, as this enzyme has a prominent role in active metabolism.

Disseminated toxoplasmosis in a patient with advanced acquired immunodeficiency syndrome

Extracerebral toxoplasmosis, with pulmonary involvement and shock, is a rare form of toxoplasmosis in patients with advanced AIDS. It can mimic pneumocystosis, histoplasmosis, and disseminated tuberculosis, and should be considered in the differential diagnosis of causes of respiratory failure and fulminant disease in this group of individuals, especially in areas where the Toxoplasma gondii infection is highly prevalent and in those without proper use of antimicrobial prophylaxis. We report the case of a 46-year-old male patient who presented to the emergency department with uremia, requiring urgent dialysis. During the laboratorial investigation, the patient had confirmed HIV infection, with a low CD4+ peripheral T-cell count (74 cells/µL). During hospitalization, the patient presented drug-induced hepatitis due to trimethoprim/sulfamethoxazole in a prophylactic dose, requiring interruption of this medication. On the 55th day of hospitalization, the patient developed refractory shock and died. At the autopsy, disseminated toxoplasmosis with encephalitis and severe necrotizing pneumonia were diagnosed, with numerous tachyzoites in the areas of pulmonary necrosis.

Clinical features and outcomes in patients with disseminated toxoplasmosis admitted to intensive care: a multicenter study

BACKGROUND

Characteristics and outcomes of adult patients with disseminated toxoplasmosis admitted to the intensive care unit (ICU) have rarely been described.

METHODS

We performed a retrospective study on consecutive adult patients with disseminated toxoplasmosis who were admitted from January 2002 through December 2012 to the ICUs of 14 university-affiliated hospitals in France. Disseminated toxoplasmosis was defined as microbiological or histological evidence of disease affecting >1 organ in immunosuppressed patients. Isolated cases of cerebral toxoplasmosis were excluded. Clinical data on admission and risk factors for 60-day mortality were collected.

RESULTS

Thirty-eight patients were identified during the study period. Twenty-two (58%) had received an allogeneic hematopoietic stem cell transplant (median, 61 [interquartile range {IQR}, 43-175] days before ICU admission), 4 (10%) were solid organ transplant recipients, and 10 (27%) were infected with human immunodeficiency virus (median CD4 cell count, 14 [IQR, 6-33] cells/µL). The main indications for ICU admission were acute respiratory failure (89%) and shock (53%). The 60-day mortality rate was 82%. Allogeneic hematopoietic stem cell transplant (hazard ratio [HR] = 2.28; 95% confidence interval [CI], 1.05-5.35; P = .04) and systolic cardiac dysfunction (HR = 3.54; 95% CI, 1.60-8.10; P < .01) within 48 hours of ICU admission were associated with mortality.

CONCLUSIONS

Severe disseminated toxoplasmosis leading to ICU admission has a poor prognosis. Recipients of allogeneic hematopoietic stem cell transplant appear to have the highest risk of mortality. We identified systolic cardiac dysfunction as a major determinant of outcome. Strategies aimed at preventing this fatal opportunistic infection may improve outcomes.

Hemophagocytic syndrome as uncommon presentation of disseminated toxoplasmosis in an immunocompetent adult from Chinese Kunming

Hemophagocytic syndrome is a rare disease that is often fatal, despite treatment. An immunocompetent patient was presented with fever, hepatosplenomegaly, cytopenias, hypertriglyceridemia, hypofibrinogenemia, and hyperferritinemia, which conformed to a hemophagocytic syndrome diagnosis. Despite broad antibiotic treatment, the patient's clinical condition rapidly deteriorated and he died within 8 days of admission. Blood cultures and a serology test were negative; however, based on morphological characteristics, tissue cysts Toxoplasma gondii were found in the bone marrow. Based on polymerase chain reaction analysis, identity of the parasite was confirmed. Although very rare, T. gondii-associated hemophagocytic syndrome should be suspected in the case of cytopenia or multiorgan failure symptoms. To our knowledge, this is the first fatal toxoplasmosis case reported from China.

Disseminated toxoplasmosis presenting as septic shock five weeks after renal transplantation

We discuss a case of acute disseminated toxoplasmosis in a renal transplant recipient presenting with septic shock. Our literature review of disseminated toxoplasmosis presenting as septic shock reveals a disease process that is rapid and almost uniformly fatal. This unusual presentation warrants a high index of suspicion in transplant recipients with immediate administration of appropriate empiric antimicrobials.

Acute toxoplasmoses in immunocompetent patients hospitalized in an intensive care unit in French Guiana

Atypical Toxoplasma gondii strains, unrelated to archetypal clonal lineages (I, II, III), have been reported more frequently over the last decade in areas other than Europe and North America. A newly described form of toxoplasmosis, 'Amazonian toxoplasmosis' (AT), has been reported since 2002 in French Guiana. It is characterized by severe cases and atypical strains linked to a neotropical forest-based cycle. We report on the cases of AT that required intensive care management. We performed a prospective observational study on hospitalized adults in the Intensive Care Unit (ICU) from 2002 to 2008. Clinical and laboratory data, microbiological findings and outcomes were recorded. Data, including the ICU simplified acute physiology score and the pneumonia severity index, were calculated. Epidemiological risk factors for AT were assessed through questionnaires. Eleven non-immunodeficient patients were admitted to the ICU in Cayenne for life-threatening pneumonia associated with disseminated toxoplasmosis. Mechanical ventilation was necessary in seven patients, four of whom required immediate orotracheal intubation. Cardiac and ophthalmological abnormalities were found in five and four patients, respectively. One patient died from multiple organ failure. The genetic characterization of Toxoplasma DNA using six microsatellite markers revealed unique and atypical genotypes in eight patients. All patients presented epidemiological risk factors for AT. In French Guiana, significant T. gondii-related infectious syndrome associated with the lungs, a high level of LDH activity and the reported risk factors for AT was strongly suggestive of disseminated toxoplasmosis with a possible trend toward life-threatening pneumonia.

Importance of nonenteric protozoan infections in immunocompromised people

There are many neglected nonenteric protozoa able to cause serious morbidity and mortality in humans, particularly in the developing world. Diseases caused by certain protozoa are often more severe in the presence of HIV. While information regarding neglected tropical diseases caused by trypanosomatids and Plasmodium is abundant, these protozoa are often not a first consideration in Western countries where they are not endemic. As such, diagnostics may not be available in these regions. Due to global travel and immigration, this has become an increasing problem. Inversely, in certain parts of the world (particularly sub-Saharan Africa), the HIV problem is so severe that diseases like microsporidiosis and toxoplasmosis are common. In Western countries, due to the availability of highly active antiretroviral therapy (HAART), these diseases are infrequently encountered. While free-living amoebae are rarely encountered in a clinical setting, when infections do occur, they are often fatal. Rapid diagnosis and treatment are essential to the survival of patients infected with these organisms. This paper reviews information on the diagnosis and treatment of nonenteric protozoal diseases in immunocompromised people, with a focus on patients infected with HIV. The nonenteric microsporidia, some trypanosomatids, Toxoplasma spp., Neospora spp., some free-living amoebae, Plasmodium spp., and Babesia spp. are discussed.

Transmission of toxoplasmosis in two renal allograft recipients receiving an organ from the same donor

Toxoplasma gondii is a ubiquitous protozoan parasite. After acute infection it continues to exist as cysts in the muscles and brain. Recipients of organ allografts are susceptible to the disease as a result of reactivation of quiescent infection either by transmission from the organ donor or by consumption of undercooked meat. We describe 2 cases of fatal toxoplasmosis in renal allograft recipients who received their organs from the same cadaveric donor. Both recipients died 5 weeks after renal transplantation, within days of each other. Multiorgan involvement with toxoplasmosis was demonstrated at autopsy. No evidence of the parasite was found in the transplanted kidney, either at the time of insertion or at autopsy. Neither recipient had serologic evidence of previous exposure to T. gondii. The donor had positive IgG but indeterminate IgM antibodies suggesting acute infection at the time of death; there was no clinical suspicion that the donor died from acute toxoplasmosis. We conclude that toxoplasmosis was transmitted by the donor kidneys. In an attempt to minimize the possibility of future transmission, donors are now tested for anti-toxoplasma IgM antibodies and recipients are treated with trimethoprim/sulfamethoxazole for the first 6 months after renal transplantation.

Fulminant toxoplasmosis causing fatal pneumonitis and myocarditis

The obligate intracellular protozoa Toxoplasma gondii is a serious cause of morbidity and mortality in patients with AIDS. Toxoplasmosis most frequently manifests as life-threatening encephalitis, although extracerebral sites may be involved with or without toxoplasmic encephalitis. Consequently, toxoplasmosis can present in an unusual manner, and may not be included in the differential diagnosis in the absence of encephalitic symptoms. There are few reports of fulminant toxoplasmic myocarditis resulting in death. Toxoplasmic pneumonitis is responsible for less than 1% of HIV-related pulmonary complications, and can occasionally cause fatal septic shock. Two such clinicopathological presentations of toxoplasmosis are reported here. One patient presented with cardiorespiratory signs and symptoms, whilst the second patient presented with pneumonitis and renal failure. Neither patient was initially known to be HIV-infected, nor did they have clinical symptoms indicating toxoplasmic encephalitis. Toxoplasmosis was only diagnosed on autopsy and had resulted in death by causing a fulminant myocarditis and a pneumonitis. As overwhelming toxoplasmosis infection may prove rapidly fatal, these two case reports serve as a clinical reminder to consider toxoplasmosis in the differential diagnosis of HIV-infected patients who present with severe cardiorespiratory signs and symptoms. Furthermore, the cases emphasize the potential importance of early tissue biopsy in patients presenting with immunosuppression-associated organ failure, and show the importance of requesting a postmortem examination if the cause of death cannot be ascertained in vivo.

[Septic shock due to congenital disseminated toxoplasmosis?]

Congenital toxoplasmosis secondary to maternal primary infection acquired late during pregnancy is generally asymptomatic at birth. We report a case of a newborn infant whose mother had been infected between the 27th and the 33rd week of gestation. No treatment had been given during gestation. The infant had a disseminated form of toxoplasmosis with hepatosplenomegaly, pneumonitis, purpura, hepatitis. On the third day of life, he developed shock. The patient died early despite therapy. Septic shock is unusual in congenital toxoplasmosis, although it has been described in immunocompromised patients, notably in patients infected with the human immunodeficiency virus.

The association of serum lactate dehydrogenase level with selected opportunistic infections and HIV progression

BACKGROUND

The purpose of this study was to determine the association of serum lactate dehydrogenase (LDH) levels with certain opportunistic infection and to determine an association between LDH levels and CD4+ lymphocyte counts.

METHOD

We studied 352 patients retrospectively with HIV infection and one of the following infections: histoplasmosis; toxoplasmosis; tuberculosis (pulmonary and disseminated); bacterial pneumonia; Pneumocystis carinii pneumonia. Demographic and clinical data were obtained from the Adult Spectrum of Diseases (ASD) database in New Orleans. Bivariate and multivariate analysis were used to determine the association between LDH levels and opportunistic infections and CD4+ lymphocyte counts.

RESULTS

Patients with a serum LDH level <225 IU/L had a mean CD4+ lymphocyte count of 159/dl (SE 19.3) as compared to patients with a serum LDH level > or =225 IU/L, who had a mean CD4+ lymphocyte count of 58/dl (SE 6.9) (P<0.01). Non-Caucasian race, a diagnosis of histoplasmosis, disseminated tuberculosis or Pneumocystis carinii pneumonia, and CD4+ lymphocyte count were significantly associated with a serum LDH level > or =225 IU/L in the bivariate analysis. In a multivariate analysis, after controlling for race and CD4+ lymphocyte count, the only diagnoses that were significantly associated with the serum LDH level were definitive Pneumocystis carinii pneumonia and toxoplasmosis. Having a higher LDH level was not associated with early mortality.

CONCLUSIONS

Although not diagnostic, serum LDH levels could be used as an adjunctive marker in certain opportunistic infections. There is an inverse relationship between serum LDH levels and CD4+ lymphocyte counts in this group.

Acute toxoplasmosis leads to lethal overproduction of Th1 cytokines

Virulence in Toxoplasma gondii is strongly influenced by the genotype of the parasite. Type I strains uniformly cause rapid death in mice regardless of the host genotype or the challenge dose. In contrast, the outcome of infections with type II strains is highly dependent on the challenge dose and the genotype of the host. To understand the basis of acute virulence in toxoplasmosis, we compared low and high doses of the RH strain (type I) and the ME49/PTG strain (type II) of T. gondii in outbred mice. Differences in virulence were reflected in only modestly different growth rates in vivo, and both strains disseminated widely to different tissues. The key difference in the virulent RH strain was the ability to reach high tissue burdens rapidly following a low dose challenge. Lethal infections caused by type I (RH) or type II (PTG) strain infections were accompanied by extremely elevated levels of Th1 cytokines in the serum, including IFN-gamma, TNF-alpha, IL-12, and IL-18. Extensive liver damage and lymphoid degeneration accompanied the elevated levels of cytokines produced during lethal infection. Increased time of survival following lethal infection with the RH strain was provided by neutralization of IL-18, but not TNF-alpha or IFN-gamma. Nonlethal infections with a low dose of type II PTG strain parasites were characterized by a modest induction of Th1 cytokines that led to control of infection and minimal damage to host tissues. Our findings establish that overstimulation of immune responses that are normally necessary for protection is an important feature of acute toxoplasmosis.

Regulation and function of T-cell-mediated immunity during Toxoplasma gondii infection

The intracellular protozoan Toxoplasma gondii is a widespread opportunistic parasite of humans and animals. Normally, T. gondii establishes itself within brain and skeletal muscle tissues, persisting for the life of the host. Initiating and sustaining strong T-cell-mediated immunity is crucial in preventing the emergence of T. gondii as a serious pathogen. The parasite induces high levels of gamma interferon (IFN-gamma) during initial infection as a result of early T-cell as well as natural killer (NK) cell activation. Induction of interleukin-12 by macrophages is a major mechanism driving early IFN-gamma synthesis. The latter cytokine, in addition to promoting the differentiation of Th1 effectors, is important in macrophage activation and acquisition of microbicidal functions, such as nitric oxide release. During chronic infection, parasite-specific T lymphocytes release high levels of IFN-gamma, which is required to prevent cyst reactivation. T-cell-mediated cytolytic activity against infected cells, while easily demonstrable, plays a secondary role to inflammatory cytokine production. While part of the clinical manifestations of toxoplasmosis results from direct tissue destruction by the parasite, inflammatory cytokine-mediated immunopathologic changes may also contribute to disease progression.

Toxoplasma gondii triggers granulocyte-dependent cytokine-mediated lethal shock in D-galactosamine-sensitized mice

To investigate the capacity of Toxoplasma gondii to induce cytokine-mediated toxicity, we employed a murine model of lethal shock in which hypersensitivity to microbial toxins is induced by D-galactosamine (D-Gal). Animals injected with D-Gal and tachyzoite lysate died within 12 to 24 h, whereas administration of D-Gal or lysate alone was nonlethal. Analyses of plasma cytokines revealed peaks of tumor necrosis factor (TNF) alpha and interleukin-12 (IL-12) 1 and 3 to 5 h after injection, respectively, and gradually rising levels of gamma interferon (IFN-gamma) continuing until death. Nitric oxide (NO) levels in serum paralleled IFN-gamma production. Transaminase assays revealed elevated levels of liver-associated enzymes in sera of lethally injected mice, indicating severe hepatic damage. Depletion of IL-12, TNF, IFN-gamma, and NO rescued mice from the lethal effect of antigen (Ag) and D-Gal. T-cell-deficient animals remained sensitive to D-Gal and lysate, suggesting that T lymphocytes do not contribute to the response. Nevertheless, monoclonal antibody (MAb)-mediated granulocyte depletion completely abrogated D-Gal- and Ag-induced mortality and accompanying liver pathology. Finally, mice acutely infected with T. gondii displayed highly elevated NO and liver enzyme levels in serum immediately prior to death, and administration of anti-TNF MAb prolonged survival by approximately 24 h. Our results demonstrate that T. gondii induces lethal inflammatory cytokine shock in D-Gal-sensitized animals and suggest that a similar pathology may contribute to manifestations of acute toxoplasmosis.

Toxoplasmose chez les patients immunodéprimés. Apport à la connaissance de l'infection toxoplasmique

Toxoplasmosis can be a severe infection in immunosuppressed patients. In these patients it can present as collected encephalitis, diffuse hypoxemic pneumopathy, or disseminated infection with fatal outcome. These presentations are observed mainly in HIV-infected patients, and less frequently in bone-marrow transplanted, or heart or heart and lung transplanted patients, or in patients given long term steroids or immunosuppressive therapy. The disease is due most often to the reactivation of latent persistent forms of the parasite at a moment of depression of host defense mechanisms, with local reactivation, and/or hematogenous dissemination. In some cases, the disease is favored by an insufficient protective response after primary infection. Treatment, based on the pyrimethamine-sulfadiazine combination should be continued as long as a profound immunosuppression is present. Prevention is based on recommendations to avoid acquisition of the parasite for seronegative patients, and on chemoprophylaxis, using cotrimoxazole as first line regimen, in patients already infected with Toxoplasma gondii.

Disseminated toxoplasmosis and acquired immunodeficiency syndrome: diagnosis by transmission electron microscopy

A 43-year-old, bisexual, black man with acquired immunodeficiency syndrome (AIDS), detected by CD4 lymphocyte criteria alone, presented with low-grade fever, chills, malaise, and watery diarrhea of 2 days' duration. Over the next 5 days, he developed a fulminant septicemia-like illness with progressive hypotension, disseminated intravascular coagulation, and very high serum lactic acid dehydrogenase (2,150 U/L) and serum creatine phosphokinase (5,395 U/L) levels, and died. The cause of this illness was not clinically apparent. A bone marrow biopsy performed on the day of his death revealed intracytoplasmic clusters of 3 microns long, oval, basophilic organisms, the exact nature of which was not evident by light microscopy. The diagnosis of disseminated toxoplasmosis (DT) was made only after electron microscopic study of the bone marrow revealed organisms with features typical of Toxoplasma gondii tachyzoites. These features included a multilayered pellicle, a pointed anterior end containing a conoid, up to nine rhoptries, sparse micronemes, and a posterior end containing a nucleus. Some of the organisms had divided by internal budding or endodyogeny. This case illustrates the value of transmission electron microscopy in making the diagnosis of DT.

Fulminant disseminated toxoplasmosis in an HIV patient

Disseminated toxoplasmosis in AIDS is a rare condition. We present an unusual case of a fulminant form of disseminated toxoplasmosis in a young male homosexual. He was a 30-year-old HIV-positive (diagnosed 4 months earlier), admitted with a 5-day history of diarrhea, vomiting, fever, and cough. He had been generally healthy except for an 8-week history of weight loss and malaise. On admission, except for a temperature of 37.6 degrees C, the physical examination was normal. He was treated symptomatically. Four days after admission he suddenly became short of breath. Despite intensive management, he continued to deteriorate and expired 6 h later. Postmortem examination revealed disseminated toxoplasmosis involving the heart, lungs, brain, stomach, small intestine, and colon. This is an unusual presentation of disseminated toxoplasmosis because of its rapid course with no prior indication of infection. To our knowledge, such an atypical and rapid downhill course of toxoplasmosis (with minimal clinical and laboratory features) has not been reported previously. Increased awareness of this infection in all HIV patients and its possibly rapid course is needed.

Disseminated toxoplasmosis in AIDS patients--report of 16 cases

Between June 1986 and October 1992, disseminated toxoplasmosis was diagnosed in 16 AIDS patients. 13 cases were diagnosed at autopsy where multiple organ involvement was documented in all 13. Three patients were diagnosed intra vitam. All 3 survived with appropriate treatment. Clinical features indicative of disseminated toxoplasmosis were: fever of unknown origin between 39 degrees and 40 degrees C in 16 cases, clinical signs suggestive of sepsis or septic shock in 15, with progression to multiorgan failure in 10, disseminated intravascular coagulopathy in 6, confusion, disorientation or apathy in 13 and lack of a systemic pneumocystis carinii prophylaxis in all 16. Typical laboratory markers were: CD4 cell counts below 100 x 10(6)/l in 16 cases, elevation of serum lactic dehydrogenase in 16 and creatine phosphokinase (in 4/6), normal or only slightly elevated C-reactive protein (in 9/11), positive Toxoplasma gondii IgG antibodies in 15/16 and negative IgM antibodies in all 16. Lesions indicative of cerebral toxoplasmosis were visualized on cranial computerized tomography in only 3/10 evaluated patients. In patients with advanced HIV infection presenting with a systemic illness, including the clinical and laboratory features described above, systemic Toxoplasma gondii infection must be included in the differential diagnosis. In these patients, specific and if warranted, invasive diagnostic procedures followed by early vigorous therapeutic intervention should be considered.