54 Hemolytic Anemia resulting from Infections with Miroorganisms Flashcards
Mechanisms that may lead to hemolysis during infections
Direct invasion of or injury
Malaria, babesiosis, and bartonellosis
Mechanisms that may lead to hemolysis during infections
Elaboration of hemolytic toxins
Clostridium perfringens
The world’s most common cause of hemolytic anemia
Malaria
Specialized invasion proteins that invade in Malaria
Erythrocyte binding-like (EBA) and reticulocyte homology (RH) protein families
Bind to receptors on the erythrocyte surface, including glycophorins A/B/C, CR1 (CD35), and basigin (CD147)
Erythrocytes infected with Plasmodium falciparum develop surface knobs that contain receptors, especially the P. falciparum erythrocyte membrane protein-1 (PfEMP-1) for endothelial proteins.
All parasites bind to ________ and___________ found on endothelial surfaces
CD36 antigen (platelet glycoprotein IV)
Thrombospondin
Some bind to the intercellular adhesion molecule-1 (ICAM-1), and a few bind to the vascular cell adhesion molecule (VCAM)
TRUE OR FALSE
The anemia of falciparum malaria is characteristically a normocytic-normochromic anemia with a paucity of reticulocytes. If microcytosis is present, the concomitant presence of α- or β-thalassemia or iron deficiency should be considered.
TRUE
The anemia of falciparum malaria is characteristically a normocytic-normochromic anemia with a paucity of reticulocytes.
If microcytosis is present, the concomitant presence of α- or β-thalassemia or iron deficiency should be considered.
Disease conditions that interfere with invasion of erythrocytes by parasites (malaria) and their proliferation
Resistance to malaria
G6PD deficiency, Southeast Asian ovalocytosis , CR1 deficiency, the thalassemias, sickle cell anemia, and other hemoglobinopathies
Plasmodial species that are notably associated with hemolytic anemia
P. falciparum, P. vivax
Plasmodial specie that invades only young red cells
P. vivax
Plasmodial specie that attacks both young and old cells, more severe and is the most deadly type
P. falciparum
The only plasmodium that infects humans that is zoonotic
It is not transmitted from human to human by a mosquito vector
Causes severe malaria with a frequency similar to P. falciparum, and this includes a high frequency of intravascular hemolysis
P. knowlesi
TRUE OR FALSE
Plasmodium falciparum also decreases the erythropoietin response
TRUE
Plasmodium falciparum also decreases the erythropoietin response
Resulting in less erythropoiesis than expected for the degree of anemia, reticulocytopenia, and, coincidentally, striking dyserythropoiesis with red cell stippling, cytoplasmic vacuolization, nuclear fragmentation and multinuclearity
Intravascular hemolysis in ________ malaria may be more frequent than in any other type of malaria.
P. knowlesi
The fever associated with malaria, accompanied by rigors, headache, abdominal pain, nausea and vomiting, and extreme fatigue, is characteristically cyclic, varying in frequency according to the malaria type.
BLACKWATER FEVER
Febrile paroxysms of malaria
P. vivax:
P. malariae:
P. falciparum:
P. vivax: every 48 hours
P. malariae: every 72 hours
P. falciparum: daily
Mechanism of periodic fever in malaria
Schizont rupture
Considered the standard of diagnosis in Malaria
Identification of the malarial parasite on the blood film
Involves examination of a thick and thin blood film preparation
In nonimmune patients, examination of the blood film for malarial parasites should be made for at least 3 days after onset of symptoms because parasitemia may not reach detectable levels for several days.
Alternative and supplementary technique used to demonstrate the appropriate DNA sequences in the blood or the use of automated hematology analyzers to identify parasites as part of a routine complete blood count investigation.
Polymerase chain reaction (PCR)
If more than____% of the red cells infected contain parasites, the infection is almost certainly with P. falciparum.
5%
This finding is regarded as pathognomonic of P. falciparum
The finding of two or more rings within the same red cells
Approximately 15% of the cases were severe as indicated by one or more of the following:
- Hemoglobin less than 70 g/L
- Parasitemia of greater than 5% of red cells
- Acute renal injury
- Acute respiratory distress syndrome
- Jaundice and requiring rapid treatment and intensive care
Other names for Bartonellosis
Oroya Fever
Carrión disease
Human bartonellosis is transmitted by
Sand fly (Lutzomyia spp)
The only reservoir for this organisms is human beings.
Mechanism of Bartonellosis
Red cells are rapidly removed from the circulation, apparently both by liver and spleen.
The organism does not grow within the red cell but rather adheres to its exterior surface
The osmotic fragility of the red cells is normal.
Di sira yung cell; nskadikit lang
Bartonella protein that causes erythrocytes to acquire trenches, indentations, and invaginations has been purified from culture broths and has been called
Deformin
Two B. bacilliformis genes that encode for this protein that greatly enhance the ability of Escherichia coli to invade erythrocytes
Invasion-associated locus proteins A and B, designated ialA and ialB
Represents the early, invasive stage of a chronic granulomatous disorder of Bartonellosis
Oroya fever
The second stage of B. bacilliformis infection characterized by a skin eruption of cutaneous vascular nodular tumors (hemangioma-like) often on the face and extremities
Verruca peruviana (also called verruca peruana)
Immunosuppression is an accompaniment of B. bacilliformis infection, leading to secondary infections, exemplified by staphylococcal and Salmonella bacteremia or Toxoplasma bacteremia and myocarditis.
Diagnosis of Bartonellosis is established by
Demonstrating the presence of the organism on the erythrocytes
Giemsa-stained blood films reveal red-violet rods varying in length from 1 to 3 μm and in width from 0.25 to 0.2 μm.
Treatment for patients with Oroya fever
Aminoglycosides, cephalosporins, macrolides, quinolones, penicillins, tetracyclines, and others (eg, rifampin)
Babesiae are intraerythrocytic protozoa known as
Piroplasms
Babesiosis is transmitted by the bite of
Tick:Ixodes scapularis
Babesiae species that infect humans
Babesia microti, Babesia divergens, Babesia duncani, and Babesia venatorum
Cases of babesiosis transmitted by transfusion are mostly caused by
Mostly caused by Babesia microti but also by Babesia duncani
Morphology of Babesia in thin blood films
Darkly stained ring forms with light blue cytoplasm
Maltese cross tetrad: consists of four daughter cells of Babesia connected by cytoplasmic bridges
Test of choice for confirmation of an active infection in an individual bearing antibodies to Babesia and for following the response to therapy
Immunofluorescent tests for antibodies to Babesia and PCR-based diagnostic tests
TRUE OR FALSE
Most mild B. microti infections respond without treatment.
TRUE
Most mild B. microti infections respond without treatment.
Treatment for Babesiosis
Clindamycin and quinine
Atovaquone and azithromycin
Tafenoquine
Treatment for recalcitrant cases of Babesiosis
Whole-blood or red cell exchange
Infection that most likely to occur in patients who have undergone septic abortion, after acute cholecystitis, as a result of an intrahepatic abscess, and, rarely, after amniocentesis (amnionitis)
Clostridium perfringens (formerly Clostridium welchii)
Are gram-positive, encapsulated, spore-forming, anaerobic bacilli
Causes gas gangrene in soft tissues
Clostridium perfringens (formerly Clostridium welchii)
Toxin that is the agent that causes intravascular hemolysis in Clostridium perfringens septicimeia
Lysolecithins
The α-toxin of C. perfringens is a lecithinase C that reacts with lipoprotein complexes at cell surfaces, liberating potent hemolytic substances, lysolecithins.
TRUE OR FALSE
The lysis of red cells (decreasing packed red cell volume) and the high plasma hemoglobin can produce a marked dissociation between the blood hemoglobin and hematocrit level.
TRUE
The lysis of red cells (decreasing packed red cell volume) and the high plasma hemoglobin can produce a marked dissociation between the blood hemoglobin and hematocrit level.
For example, hematocrits approaching zero with blood hemoglobins as high as 8 g/dL can occur.
Therapy for Clostridium perfringens septicimeia
Antibiotic therapy, fluid support, red cell transfusion, and when appropriate surgical debridement
Pathogens that produce red cell agglutination in vitro
Haemophilus influenzae, E. coli, and Salmonella spp.
Microorganisms may play a role in precipitating autoimmune hemolytic disease
Mycoplasma pneumoniae, measles, cytomegalovirus, varicella, herpes simplex, influenzas A and B, Epstein-Barr, human immunodeficiency virus, and coxsackievirus
Microangiopathic hemolytic anemia may be triggered by a variety of infections:
Shiga toxin-producing E. coli, Shigella dysenteriae type 1, Campylobacter spp., and Aspergillus spp.
