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BII > Mark Thomas > Flashcards

Mark Thomas Flashcards

1
Q

What are the name of two yest strains that can cause infection in patients with AIDS?

A

Candida albicans - oral or vaginal thrush

Cryptococcus neoformans - meningitis

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2
Q

How would you treat cryptococcal meningitis?

A

With IV amphotericin B
or
IV or oral fluconazole

For 6 weeks

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3
Q

What is a type of mold and what does it cause?

A

dermatophytes - tinea, pityriasis versicolor

Treat with a topical azole

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4
Q

What is the treatment for febrile neutropenia?

A

Tazocin (active against almost all aerobic bacteria) and gentamicin (active against almost all aerobic gram - ve bacilli)

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5
Q

What type of organism causes malaria and what is the specific species?

A

Protozoa infection.

Plasmodium falciparuim - potentially fatal.

Plasmodium vivax - relatively benign

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6
Q

What is the lifecycle of plasmodium vivax and plasmodium falciparum?

A

Anopheles mosquito becomes infected by biting and sucking the blood of an infected person. The protozoa then go to the stomach, mate and then go to the salivary glands (sporozoites). The mosquito then bites another person and injects saliva into the bite. The malaria parasites then get into the blood, which infects the persons liver and multiples there (merozoites). This does not cause damage to the liver. They can then enter the blood and invade RBCs. Incubation period of 10 days before they can infect RBCs -> symptoms. RBCs burst and bits of haemoglobin and other RBC components is released into the blood and responds by shivering to cause fever. Then cools down by sweating.

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7
Q

What are the symptoms of malaria?

A

Fever, rigor, malase, headache, coma, sweating and shivering

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8
Q

How do you diagnose malaria?

A

Just normal microscopy of the blood with staining. Can see parasites within RBC.

Antigen detection in the blood.

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9
Q

What makes plasmodium falciparium more dangerous than plasmodium vivax?

A

Plasmodium falciparum can infect any RBC. Causes a high proportion to be infected.
Plasmodium falciparum causes adhesion molecules are expressed that causes the RBC to stick to the capillaries, which slows blood flow and reduces oxygen diffusion. This occurs particularly in the brain and the kidneys. -> coma and death.

Plasmodium vivax only infects fresh RBCs and does not cause that adhesion molecule so no coma, death or kidney failure.

Some of the protozoa become latent in the liver and cause relapses with plasmodium vivax.

No relapses with plasmodium falciparum.

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10
Q

What are the differences between the two main types of salmonellae?

A

Both gram negative bacilli.

Salmonella entertidis: Acquired from animals and birds (not humans). Infects the colonic mucosa (colon only) and causes colitis. Common cause of gastroenteriitis in NZ. Inflammation of the colon causes fever.

Salmonella typhi (typhoid fever) - acquired from people, swallowing poo. Infects peyers patches of the ileum. Multiplies in macrophages. Causes bacteraemia and septicaemia. Common cause of persistent fever in travelers. Often not diarrhea. Not usually vomiting.

After illness it can multiply in the gallbladder asymptomatically and that is how it is transmitted into the poo to infect others. Can remain for the remainder of their life (typhoid Mary).

Causes fever, shivering, sweats, cough, headache, confusion. Can be confused with Malaria.

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11
Q

How can typhoid fever cause death?

A

The peyers patches can become inflamed and necrotic and if that goes through the intestinal wall then peritonitis. Or it can rupture a blood vessel causing hemorrhage.

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12
Q

How do you diagnose and treat typhoid fever?

A

Blood cultures.

Treat with ceftriaxone or ciprofloxacin O

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13
Q

How can an URTI cause ottitis media?

A

URTI cause swelling of mucosal membranes to recruit more leukocytes and antibodies. This can make it difficult to breath but also block the eustation tube. The fluid that then drains to the middle ear is stuck and bacteria can grow in it.

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14
Q

What are the common causes of URTI?

A

Streptococcus pyogenes (50%)
Streptococcus pneumoniae
Haemophilus influenzae
Respiratory viruses (50%)

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15
Q

What differs between a URTI caused by streptococcus pyogenes and a respiratory virus?

A

S pyogenes causes a localised and more intense pharyngitis (throat only) - fever, pain, dysphagia, adenopathy, red pharynx

Respiratory viruses infect the nose, throat, trachea and cause a less intense and more diffuse illness. - rhinorrhoea, horse voice, cough, conjunctival signs

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16
Q

How do you determine if a URTI is caused by S pyogenes?

A 
GIVE 1 POINT IF
Fever
No cough
Tender cervical LN
Tonsil swelling
Under 14 yo

4 or above = 50% that S pyogenes

17
Q

What does lancefield serogrouping do?

A

Identifies different types of bacteria.

Antibodies have been developed against different groups of bacteria. I.E the antibodies recognised a antigen that is expressed by some bacteria. If you put some of the bacteria with the corresponding antigen the antibodies will cross-link and cause agglutination.

Group A streptococci

18
Q

What is the cause of an early diastollic murmer?

A

Aortic regurgitation

19
Q

What valves can be affected in endocarditis?

A

Aortic and/or mitral valve

20
Q

What is the pathogenesis of endocarditis?

A

Turbulent flow through abnormal valve (congenital or RHD) -> Rough surface. platelets and fibrin attach to damaged valvular epithelium forming sterile vegetations -> Transient bacteriemia seed in vegetations -> vegetation enlarges and sheds infected emboli -> vascular destruction.

21
Q

What organisms cause infection in endocarditis?

A

Viridans streptocci (mouth), staph aureus (nose), enterococcus faecalis (gut)

22
Q

What kills you in endocarditis?

A

Heart failure due to valve failure or emboli to somewhere important (brain, lungs) - 100% fatal without treatment

23
Q

How do you diagnose endocarditis?

A

3 blood cultures 20 minutes apart
Constant bacteriemia - same pathogen.

Show vegetation on a heart valve. - EEG

Listen for a murmur.
Look for emboli

24
Q

How do you treat endocarditis?

A

Identify bacteria

Choose sensitive antibiotic and determine concentration required.
Needs to be bactericidal.

Treatment prior to culture results: penicillin plus flucovacillin plus gentimicin

Viridans streptocci:
Penicillin with or without gentamicin

S aureus:
Flucoxacilin with or without gentamicin

Enterococcus faecalis:
Amoxycillin with or with out gentimicin

25
Q

What are two viruses that affect lymphocytes and what do they cause?

A 
HIV
EBV
CMV
S aureus (focal)
M tuberculosis (focal)

Lymphadenopathy
Fever

26
Q

What are the causes of lymphadenopathy?

A

Focal: proliferation of lymphocytes in response to infection.
Proliferation of malignant cells that have metastised.

Widespread:
Proliferation of malignant lymphocytes
Inflammation within nodes resulting from killing of lymphocytes infected with a virus

27
Q

What are the features of EBV and CMV?

A

DNA viruses
Acute infection followed by latent infection with reactivation or chronic infection

Cause glandular fever (enlarged glands)
More sever for adults than children

Virus transmitted in saiva
Incubated 4-6 weeks
Illness for 1-2 weeks

Fever, sore throat, malaise, fatigue, cervical adenopathy

Recover but persistent salivary exertion

28
Q

How is EBV glandular fever diagnosed?

A

Symptoms -

Look at peripheral blood film looking for atypical lymphocytes.
Liver function tests abnormal. Elevated WBCs.

Monospot test - isolate serum with RBCs from sheep or cows -> coagulation if present.

Elisa for EBV antibodies or EBV antigens

29
Q

How is CMV glandular fever diagnosed?

A

Look at peripheral blood film looking for atypical lymphocytes.
Liver function tests abnormal.
Elevated WBCs.

Detection of antibodies or CMV in the blood.

30
Q

Has is HIV diagnosed?

A

Presence of anti-HIV antibodies in the blood with ELISA

PCR to detect RNA in blood - more expensive and slow

31
Q

How does HIV replicate?

A

Envelope made from membrane of T cell.

GP120 binds to the Th cell CD4 and CCR5.

The RNA is inserted into the cytoplasm, which is reverse transcribed into DNA.

The DNA is then shuttled into the nucleus and is inserted into the host cell DNA.

When T cell is activated, The DNA is converted to RNA goes to the ribosomes and the HIV proteins are made.

New virus buds out.

32
Q

What causes the glandular fever like symptoms in HIV?

A

Killing of the infected lymphocytes - causes swelling, tenderness and fever with sore throat. Happens at the point when CD8 T cells are activated - 4-6 weeks

BII (14 decks)

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