Coagulation abnormalities in patients with Mediterranean spotted fever

Rickettsia conorii: Unusual case of acute aortic thrombosis

OBJECTIVES

Mediterranean spotted fever is a common zoonosis in Europe caused by Rickettsia conorii bacterium. Among its wide range of clinical presentations, arterial thrombosis of large vessels has never been described before.

METHODS

We report a case of a complete acute infrarenal aortic thrombosis in a 61-year-old male with R. conorii infection.

RESULTS AND CONCLUSION

The patient was successfully operated using open aortic surgery and subsequent treatment with doxycycline. To our knowledge, this is the first report of aortic thrombosis associated with infection by this parasite, extending the clinical spectrum of the disease.

Endothelial cell infection and hemostasis

As an important component of the vasculature, endothelial cell lining covers the inner surface of blood vessels and provides an active barrier interface between the vascular and perivascular compartments. In addition to maintaining vasomotor equilibrium and organ homeostasis and communicating with circulating blood cells, the vascular endothelium also serves as the preferred target for a number of infectious agents. This review article focuses on the roles of interactions between vascular endothelial cells and invading pathogens and resultant endothelial activation in the pathogenesis of important human diseases with viral and bacterial etiologies. In this perspective, the signal transduction events that regulate vascular inflammation and basis for endothelial cell tropism exhibited by certain specific viruses and pathogenic bacteria are also discussed.

Une fièvre boutonneuse méditerranéenne compliquée d'une embolie pulmonaire

INTRODUCTION

Thromboembolic complications were uncommon in mediterranean spotted fever.

OBSERVATION

We report a case of 55-years- old man who was admitted for mediterranean spotted fever. Two days later, the patient developed chest pain due to a pulmonary thrombosis confirmed by angio-CT. The outcome was good with heparin therapy. The investigation for another cause of thrombosis was negative.

CONCLUSION

Mediterranean spotted fever is usually a moderately severe self-limited illness. Pulmonary thrombosis was uncommon associated with severe disease.

Dermatoses from ticks

Ticks are ectoparasites that cause dermatologic disease directly by their bite and indirectly as vectors of bacterial, rickettsial, protozoal, and viral diseases. In North America, where ticks are the leading cause of vector-borne infection, dermatologists should recognize several tick species. Basic tick biology and identification will be reviewed. Tick bites cause a variety of acute and chronic skin lesions. The tick-borne diseases include Lyme disease, tick-borne relapsing fever, tularemia, babesiosis, Rocky Mountain spotted fever, other spotted fevers, ehrlichiosis, Colorado tick fever, and others. The epidemiology, clinical features, diagnosis, and treatment of these diseases are reviewed with an emphasis on cutaneous manifestations. Finally, the prevention of diseases caused by ticks is reviewed.

Protein C levels as a prognostic indicator of outcome in sepsis and related diseases

OBJECTIVE

To consider the appropriateness of protein C levels as a prognostic indicator for sepsis and related diseases.

DATA SOURCES/STUDY SELECTION

Published research and review articles related to protein C deficiency in patients with sepsis and related diseases.

DATA EXTRACTION AND SYNTHESIS

All applicable data were extracted, and relevant literature was cited to support factual statements in the text. The protein C pathway represents one of the major regulatory systems of hemostasis, exhibiting antithrombotic, profibrinolytic, and anti-inflammatory properties. Numerous studies have shown that acquired protein C deficiency is prevalent in the majority of septic patients (>85%) and is associated with increased morbidity and mortality in patients with severe sepsis and septic shock. This deficiency in protein C is not simply a transient marker for sepsis, but parallels the progress of the disease. In addition, protein C deficiency occurs in the presence of a wide range of pathogens and develops early in the disease process.

CONCLUSIONS

A review of the relevant literature suggests that protein C levels may serve as a useful prognostic indicator of outcome in sepsis and related diseases.

IL-6 and IL-8 production from cultured human endothelial cells stimulated by infection with Rickettsia conorii via a cell-associated IL-1 alpha-dependent pathway

Mediterranean spotted fever due to infection by Rickettsia conorii, is characterized by a general vasculitis. This vasculitis is thought to be due to a direct injury to endothelial cells induced by R. conorii. However, production and activity of cytokines on endothelial cells is an important pathway in inflammation, and part of the underlying mechanism of vasculitis. In the present studies, human umbilical vein endothelial cells (HUVEC) infected with R. conorii actively secrete high levels of IL-8 and IL-6 (P < 0.002, and P < 0.03, respectively, compared with uninfected cells). IL-1alpha, IL-1beta, or TNFalpha were not detected in the culture supernates. Nevertheless, IL-6 and IL-8 production was due, in a large part, to a cell-associated form of IL-1 alpha expressed on R. conorii-infected HUVEC, since production of these cytokines was suppressed by 80% (P = 0.0001) and 85% (P < 0.04) by the addition of IL-1 receptor antagonist, or anti-IL-1alpha antibodies (60% inhibition, P < 0.01 and 65% inhibition, P < 0.05, respectively) and IL-1alpha was measured after lysis of R. conorii-infected HUVEC but not in uninfected cells (P < 0.01). Rickettsial lipopolysaccharide does not seem to be involved, since polymyxin B did not reduce cytokine secretion. On the contrary, infection by intracellular R. conorii appears to be necessary to induce IL-1alpha and subsequently IL-8, since formalin-fixed R. conorii did not induce cytokine production. These observations demonstrate that R. conorii-infected HUVEC secrete IL-6 and IL-8 via the induction of cell-associated IL-1alpha, providing a possible mechanism for the vasculitis observed in Mediterranean spotted fever.

Antiphospholipid antibody production during Mediterranean spotted fever

Antiphospholipid antibodies (aPLA) were discovered during the course of Mediterranean spotted fever (MSF) caused by Rickettsia conorii and characterized by endothelial cell (EC) damage resulting from this organism's tropism for EC. In two MSF patients, two types of aPLA were identified: antiphosphatidylethanolamine antibodies detected by immunological methods and lupus anticoagulant detected by clotting assays. The persistence of both aPLA for several months after the acute phase and clinical recovery might correspond to a durable immunological response to membrane damage of EC caused by R. conorii. Their possible role in the pathophysiology of microthrombi formation observed during MSF remains to be elucidated in a study on a larger number of patients.

von Willebrand factor release and thrombomodulin and tissue factor expression in Rickettsia conorii-infected endothelial cells

Mediterranean spotted fever, a tick-borne rickettsiosis caused by Rickettsia conorii, may lead to small-vessel or deep-vein thrombosis. In order to evaluate the role of endothelial cell alteration in this lesion, we infected human endothelial cells derived from umbilical veins with R. conorii. We report the induction of two previously unreported prothrombotic mechanisms in rickettsial disease: (i) a progressive decline in thrombomodulin antigen and (ii) early expression of tissue factor, and, as described for R. rickettsii infection, later release of von Willebrand factor from Weibel-Palade bodies. Thrombomodulin expression in infected endothelial cells, measured by the thrombin-dependent activation of protein C or flow cytometric analysis, decreased steadily between 4 and 24 h after inoculation with rickettsiae. R. conorii infection induced tissue factor expression, measured by clotting assay and flow cytometric analysis, which was detectable 2 h postinoculation, reached its maximum 4 h postinoculation, and progressively decreased thereafter. Infection resulted in a relatively late release of von Willebrand factor antigen into the culture medium. A double-label immunofluorescence assay for the simultaneous evaluation of von Willebrand factor and R. conorii showed that the depletion of cytoplasmic von Willebrand factor stored in Weibel-Palade bodies was due to a direct effect of the intracellular R. conorii. These disturbances of endothelial function observed with R. conorii-infected cells may provide a paradigm for the elucidation of thrombotic pathobiology with Mediterranean spotted fever.

Mechanism of low serum sodium levels in Mediterranean spotted fever

Prominent degrees of hyponatremia are detected in the severe forms of Mediterranean spotted fever and the intensity of this abnormality parallels the severity of the infectious process. In order to determine the incidence, degree and evolution of hyponatremia in 110 patients with Mediterranean spotted fever and to explore the feasible renal mechanism that could lead to this phenomenon, serum and urinary osmolality and levels of urea, creatinine and electrolytes were measured in samples obtained at selected points (up to the fifth week) in the course of the disease, and parameters of renal function were calculated. Mean serum sodium levels of 135.6 +/- 5.5 mEq/l were detected during the acute phase of the infection. At this point, 42 patients (38.2%) had sodium concentrations less than or equal to 135 mEq/l. After recovery, mean serum sodium values were 142.5 +/- 2.5. The analysis of the parameters of renal function indirectly rules out an inappropriate antidiuretic hormone secretion or renal failure as the cause of hyponatremia. As tubular incompetence to reabsorb sodium is also rejected in these patients, a shifting of sodium to the interstitial or intracellular space may account for the phenomenon.

Secretion of tissue-type plasminogen activator and plasminogen activator inhibitor by Rickettsia conorii- and Rickettsia rickettsii-infected cultured endothelial cells

Hemostasis abnormalities have been described in patients with Mediterranean spotted fever and Rocky Mountain spotted fever. Evidence of the activation of the fibrinolytic system has been obtained in both diseases. After experimental Rocky Mountain spotted fever, an elevated level of fibrinogen was found in parallel with the activation of the fibrinolytic system and transient elevation of the tissue-type plasminogen activator. Later protein is mainly synthesized by endothelial cells. The ability to culture human endothelial cells in vitro provides a unique system to study the secretion of tissue-type plasminogen activator and of plasminogen activator inhibitor after rickettsial infection. Human vascular endothelial cells derived from the umbilical vein, when infected with Rickettsia conorii or Rickettsia rickettsii, secreted as much tissue-type plasminogen activator as control cells. The activity of plasminogen activator inhibitor however, was higher in the supernatants of infected cells than in those of control cells. This rickettsia-induced imbalance of the tissue-type plasminogen activator-inhibitor pair was a very early event after in vitro infection. The involvement of this system during Mediterranean spotted fever and Rocky Mountain spotted fever remains to be demonstrated.

New trends in Mediterranean spotted fever

Mediterranean Spotted Fever is a disease caused by Rickettsia conorii. It is endemic to the Mediterranean area, where, for the last few years, the number of cases has increased, possibly due, in part, to climatic factors. The main clinical aspects of a prospective series of 246 cases diagnosed from 1983 to 1988 are presented. The most characteristic manifestations were fever, exanthema and tache noire. Other frequent manifestations were headache, myalgia and arthralgia, and with lesser frequency, hepatomegaly, splenomegaly, gastrointestinal symptoms and conjunctivitis. Notable analytical changes are the rise of hepatic and muscular enzymes in a large number of patients. In some cases we have found signs of myositis in muscular biopsy. The evolution of our patients was usually favorable though serious and even deadly forms of the disease have been described. One of the factors that seems to greatly influence the appearance of these forms is delay in the initiation of effective treatment.

Mediterranean spotted fever in Lombardy: an epidemiological, clinical and laboratory study of 76 cases in the years 1977-1986

This paper describes the epidemiological, clinical and laboratory features of 76 cases of Mediterranean spotted fever occurring during the years 1977-1986. The patients observed all lived in the Lombardy region of Italy, which is not located on the Mediterranean Basin. Our data show the highest prevalence of the disease, as reported by other authors, in southern regions of Italy, in the same years: 1979-1983. No differences were noted between age groups or sexes, and the late spring-summer seasonality was confirmed. The clinical signs and symptoms in our cases were those common to the disease. The microimmunofluorescence method was found to be more sensitive and specific than the Weil-Felix test for serological diagnosis. Finally, we showed that doxycycline and oxytetracycline both induce rapid remission of fever.

Rickettsioses of the spotted fever group around the world

Spotted fever group rickettsioses comprise Rocky Mountain spotted fever (Rickettsia rickettsii), boutonneuse fever (R. conorii), North Asian tick typhus (R. sibirica), Queensland tick typhus (R. australis), rickettsialpox (R. akari), and Oriental spotted fever (R. japonica). Ticks or mites serve as the vector and reservoir hosts of the rickettsiae. These obligate intracellular bacteria invade vascular endothelial cells, which are damaged directly, causing increased vascular permeability. The rash usually appears in Rocky Mountain spotted fever on the third day of illness and later evolves to become petechial maculopapules in 50% of cases with involvement of the palms and soles in a similar proportion of patients. Eschar occurs in some SFG rickettsioses at the site of tick bite, but rarely in Rocky Mountain spotted fever. Diagnosis often proves difficult, and laboratory assays for antibodies to SFG rickettsiae are generally useful only in convalescence. Rickettsiae are demonstrable by diagnostic immunohistology in biopsies of rash or eschar. Empiric treatment with doxycycline, tetracycline, or chloramphenicol should be given early in the course on the basis of clinical suspicion of the diagnosis of a SFG rickettsiosis.

Murine typhus and spotted fever in Israel in the eighties: retrospective analysis

One hundred and twenty-one cases of murine typhus and spotted fever in Israel between 1976 and 1985 in the Chaim Sheba Medical Center are reviewed. Clinical manifestations of murine typhus were similar to those described previously, but those of spotted fever were different from classical Mediterranean spotted fever: rash was present in 87% but eschar was noted in only two out of 38 patients. The occurrence of relapse in eight of the 16 patients treated with chloramphenicol (seven cases of murine typhus and one case of spotted fever) was striking, particularly since none occurred in 86 patients treated with tetracycline hydrochloride (p less than 0.01). Relapses were milder than the primary illness, except for one which did not receive specific therapy and was fatal.