CPR1 - Microbiology {1.12-1.13}

What are ectoparasites?

Live on the surface of their host

What are endoparasites?

Live within the body of their host

What are obligate parasites?

Require a host for part or all of their life cycle

What are facultative parasites?

Can live either freely or parasitically

What is a vector in parasitic pathology?

Insect that transmits infectious agent from one host to the next

What is a definitive host in parasite pathology?

A host in which the parasite reaches sexual maturity (adulthood)

What is an intermediate host in parasite pathology?

A host that harbors larval or sexual stages of the parasite

What is a reservoir host in parasite pathology?

Animal (definitive host) that serves to maintain the parasites life cycle in the environment

How do animals act as a source of infection?

Act as reservoirs or intermediate hosts for zoonotic parasites

How do parasites cause mechanical damage?

Direct physical effects caused by the parasites presence or movement, ex: intestinal obstruction, tissue compression

How do parasites cause damage through products?

Secretion of harmful substances such as hydrolytic enzymes

How do parasites cause damage through immunopathology?

Host immune response ie excessive inflammation, chronic immune activation

What are the keys to diagnosing parasitic infections?

Detailed history taking: travel history, dietary habits, activities, exposure to insect vectors

What are some pertinent diagnostic methods for parasitic infections?

Morphological identification (3 samples), eosinophilia, serological tests (parasitic antigens), molecular techniques (PCR)

What are some characteristics of protozoa?

Protoplasm surrounded by cell membrane, contains numerous organelles, eukaryotic

What is the geographic distribution of Babesia spp.?

North America (Northeast and Midwest), Europe

What are the means of transmission for Babesia spp.?

Tick-borne, blood transfusions

What is the geographical distribution of Plasmodium spp. (malaria)?

Africa, Asia, South and Central America, Oceania

What are the means of transmission of Plasmodium spp. (malaria)?

Female anopheline mosquito, inoculation of infected blood

What are the major clinical symptoms of Babesia spp.?

Fever, malaise, hepatosplenomegaly, hemolytic anmeia (esp. in asplenic)

What are the clinical symptoms of Plasmodium spp. (malaria)?

Paroxysmal fever, chills, headache, hepatosplenomegaly

What are the preferred diagnostic tests for babesiosis?

Giemsa or Wright staining of thin smear, PCR, Serology

What are the preferred diagnostic techniques for Granulomatous amebic encephalitis?

Brain biopsy

What are the preferred diagnostic techniques for malaria?

Wright or Giemsa stain of thin and thick blood smear, antigen detection or PCR

What is the pathogenesis of protozoal infections?

Direct damage (RBC rupture), protozoa can infect any major tissue or organ, host immune response

What are the characteristics of Nematodes (roundworms)?

Non-segmented cylindrical bodies covered with cuticle, separate sexes, complete digestive system

What are the characteristics of Cestodes (Tapeworms)?

Segmented bodies, hermaphroditic, absorb nutrients

What are the characteristics of Trematodes (Flukes)?

Non-segmented, hermaphroditic, primitive gut

What are the major routes of transmission for helminthic infections?

Fecal-oral route, consumption of infected tissue, skin penetration, insect vector bite

What are the infection requirements of a nematode infection?

Host needs to be infected by two or more worms to produce and shed eggs

What are some diagnostic markers for nematode infections?

Identified by the unique morphology of their eggs, eosinophilia

What are the key structures of adult Cestodes (Tapeworms)?

Scolex, Neck, Strobila made of proglottids

What are proglottids in Cestodes (Tapeworm)?

Contains both male and female reproductive organs, making them hermaphroditic

What are the features of Trematodes (fluke) life cycle?

Require intermediate host (Mollusks) then transfer to definitive host (Humans)

What is bacteremia?

Presence of viable bacteria in the bloodstream

What bacteremia clinically associated with?

Sepsis/septicemia, septic shock from rapid onset, infective endocarditis from slower progression

What is viremia?

Presence of virus in the blood

What is localized disease in viremia?

Disease is caused at the portal of entry without systemic spread

What is a disseminated disease in viremia?

Disease at sites distant from the portal of entry, replicate locally→spread distantly

Infection with what causes hemolysis seen in malaria?

Plasmodium falciparum

Infection with what causes direct lysis of erythrocytes through production of hemolysin?

Clostridium perfringens

Infection with what causes an autoimmune-mediated response against blood cells?

Mycoplasma pneumoniae

What is the clinical presentation of a parvovirus B19 infection?

Mild rash illness known as fifth disease (erythema infectiosum)

What is the pathogenesis of parvovirus B19?

Multiplies in erythroid progenitors, destruction of erythroid progenitors resulting in transient inhibition of RBC synthesis

What is the severe outcome of a parvovirus B19 infection in patients with hemolytic anemia?

Exacerbates anemia leading to sever aplastic anemia

What is the severe outcome of a parvovirus B19 infection in immunocompromised patients?

Chronic anemia due to impaired viral clearance

What is the severe outcome of a parvovirus B19 infection in pregnant women?

Hydrops fetalis, miscarriage, intrauterine fetal death

What is the incubation period for Babesiosis?

Symptoms 1-8 weeks after tick bite

What are some complications of Babesiosis?

Severe hemolytic anemia, thrombocytopenia, disseminated intravascular coagulation, unstable blood pressure

What is the definitive host of Babesia spp.?

Deer tick

How is human bartonellosis (oroya fever/Carrion’s disease) transmitted?

Spread by the bite of sand flies

Where is human bartonellosis (oroya fever/Carrion’s disease) endemic to?

Peru and Ecuador

What bacteria causes human bartonellosis (oroya fever/Carrion’s disease)?

Bartonella bacilliformis

What is the pathogenesis of human bartonellosis (oroya fever/Carrion’s disease)?

Infects RBCs by adhering to outer surface causing structural damage like trenches, invagination and indentations

What are the two phases of human bartonellosis (oroya fever/Carrion’s disease)?

Acute hematic phase and chronic phase

What are the characteristics of the acute hematic phase of human bartonellosis (oroya fever/Carrion’s disease)?

Systemic febrile illness (oroya fever), severe anemia due to RBC destruction

What are the characteristics of the chronic phase of human bartonellosis (oroya fever/Carrion’s disease)?

Development of highly vascular skin lesions (verruga peruana/peruvian warts)

What is the key virulence factor of clostridium perfringens septicemia?

Alpha toxin (lecithinase C) causing lysis of erythrocytes leading to free hemoglobin in blood and urine

What is hemoglobinemia?

free hemoglobin in blood

What is hemoglobinuria?

free hemoglobin in urine

What are the complications of clostridium perfringens septicemia?

Acute renal failure, hepatic failure, more than half of patients die even with prompt treatment

How is clostridium perfringens septicemia managed?

Antibiotic therapy, fluid resuscitation and support, RBC transfusion, surgical debridement

What infections cause RBC agglutination?

Haaemophilus influenzae, E. coli, salmonella

How do bacteria cause indirect RBC destruction?

Bacterial polysaccharides absorbed into RBCs leading to agglutination by antibodies and complement mediated lysis

What viruses are linked to immune hemolytic disease?

Measles, cytomegalovirus, varicella, herpes simplex, influenza A and B, EBV, HIV, coxsackievirus

What species of plasmodium cause malaria in humans?

P. falciparum, P. vivax, P. malariae, P. ovale, P. knowlesi (Malaysia)

What is the pathogenesis of anemia caused by malaria?

Erythrocyte lysis by mature parasites, suppression of erythropoiesis, splenic destruction of erythrocytes

What are the fever symptoms of malaria?

Cold stage, Hot stage, sweat stage