Rickettsia generalidades patología inglés

Rickettsia

1. Juan Humberto Flores Treviño RICKETTSIA

2. • Obligate intracellular  parasite. • Gram negative • Parasite of arthropodsfleas, lice, ticks and mites. • No Human to human transmission. • Despite the similar name, Rickettsia bacteria do not cause rickets, which is a result of vitamin D deficiency. • In the past, positioned somewhere between viruses and true bacteria. Introduction

3.  Pleomorphic coccobacilli •  Non Motile, Non Capsulated. • Stain bluish purple with Giemsa and deep red with Machiavello. • Optimum temp for growth 32-35°C • Generally occur in cytoplasm of infective cell but in some case also occur in nucleus of cell. • Readily inactivated by physical and chemical agents, rapidly destroyed at 56°C Glutamate is key nutrient for rickettsia.

4. Pathogenesis • Rickettsia are transmitted to humans by the bite of infected arthropod vector. • Multiply at the site of entry and enter the blood stream. • Localise in the vascular endothelial cells and multiply to cause thrombosis with partial or complete occlusion of vascular lumen, lead to rupture & necrosis. • Overall pathological features of the rickettsial diseases are similar as the cause acute febrile illness, characterised by septicemia with maculopaspular rash and fever.