Clinical Microbiology 2 Flashcards by Harry James

Describe the treatment regimen used for TB

6 month course of combination antituberculent therapy;
- Rifampicin - Bacteriocidal to slow replicating organisms in necrotic foci
- Isoniazid - Bacteriocidal to fast growing mycobacteria
- Pyrazinasmide - Bacteriocidal even against slow growing mycobactria intracellularly
- Ethambutol - Bacteriocidal against slow growing mycobacteria
NB: P+E removed after 4 months

How well did you know this?

Not at all

Perfectly

Describe the structure of a granuloma

Central caseous necrosis surrounded by epithelioid macrophages, which are in turn surrounded by lymphocytes

How well did you know this?

Not at all

Perfectly

What is the common cold?

Most colds are caused by the Rhinovirus (RNA virus) but can also be caused by corona viruses (RNA viruses)

How well did you know this?

Not at all

Perfectly

What is pharyngitis?

An inflammatory condition of the pharynx and/or tonsils. It is common in children and teenagers but tends to resolve in 3-7. The most common cause is the adenovirus (DNA virus)

How well did you know this?

Not at all

Perfectly

What is croup?

A distinctive cough that occurs in children which is caused most often by the parainfluenza virus which causes inflammation of the larynx

How well did you know this?

Not at all

Perfectly

What is bronchiolitis?

A common viral LRTI in children that causes a runny nose, dry wheezy cough and difficulty breathing. It is caused by the Respiratory Syncytial Virus (RSV) which causes the bronchioles to become inflamed and plugged with mucus

How well did you know this?

Not at all

Perfectly

Describe the classification of the influenza virus

A - Can cause epidemics and pandemics
B - Will not cause a pandemic
C - Causes a mild infection

Further categorised by Haemagglutinin and Neuraminidase e.g. H1N1

How well did you know this?

Not at all

Perfectly

What is antigenic drift?

In antigenic drift of the influenza virus there are continuous point mutations in the haemagglutinin receptor that is used to bind to human cells

How well did you know this?

Not at all

Perfectly

Describe the vaccination used for influenza

2 types;

Inactivated;
- 2 A types
- 1 B type
Live; nasal spray for children

How well did you know this?

Not at all

Perfectly

What is antigenic shift?

The process by which influenza pandemics occur;

1) Animal containing the virus can infect an intermediate host which passes on to humans
2) A mixture of genetic material of viruses in multiple species is passed on to humans
3) A strain from an animal that is passed directly on to a human

How well did you know this?

Not at all

Perfectly

Describe the CURB65 tool used in pneumonia

C - Confusion 
U - Urea >7
R - Respiratory rate >30
B - BP; diastolic <90
65 - Age 65+

If the patient has 2 or more points then they are likely to have severe pneumonia

How well did you know this?

Not at all

Perfectly

Describe the SIRS criteria used to assess a patient for sepsis

Temperature 38°C
Heart Rate >90bpm
Respiratory Rate >20/min
White Blood Cells 12

If the patient has two or more points then they have sepsis

How well did you know this?

Not at all

Perfectly

What are the most common congenital infections?

T - Toxoplasma
O - Other (syphillis, HIV, chickenpox etc.)
R - Rubella
C - Cytomegalovirus
H - Herpes Simplex

How well did you know this?

Not at all

Perfectly

Describe passive immunisation

Transmission of immunoglobulins .g. hepatits immunoglobulins. However this is a short term immunisation so lifelong immunity does not occur

How well did you know this?

Not at all

Perfectly

Describe active immunity

Transmission of the antigen to allow the body to develop its own life long immunity

How well did you know this?

Not at all

Perfectly

What are live attenuated vaccines?

e.g. Polio
Contains a version of the living microbe which has been weakened so that it cannot cause disease. Weakened by growing inside a chicken embryo so that the microbe is adapted to dividing in chicken cells

How well did you know this?

Not at all

Perfectly

What are the advantages and disadvantages of live vaccines?

Advantages;
- Closest to natural infection so strongest immune response
- Life long immunity after 1 or 2 doses
Disadvantages;
- Could become virulent
- Cannot be given to the immunosuppressed

How well did you know this?

Not at all

Perfectly

What are inactivated vaccines?

e.g. Influenza
Contains a microbe which has been inactivated by chemicals (e.g. formaldehyde), heat or radiation. This destroys the genetic material therefore preventing it from being able to replicate

How well did you know this?

Not at all

Perfectly

What are the advantages and disadvantages of inactivated vaccines?

Study These Flashcards

Advantages;
- Cannot revert to virulent form
- Can be used in immunosuppressed 
- Easy to store
Disadvantages;
- Elicits weaker immune response
- Life long immunity is not always achieved so boosters may be required

What are toxoid vaccines?

Study These Flashcards

e.g. Tetanus
In some infections, it is not the bacteria that causes infection, but the toxins it produces. These toxins can be inactivated using heat, chemicals or radiation

What are the advantages and disadvantages of toxoid vaccines?

Study These Flashcards

Advantages;
- Toxoids cannot become virulent 
- Easy to store
- Individual cannot infect others
Disadvantages;
- Requires adjuvants and boosters
- Local reactions at injection sites

What are subunit vaccines?

Study These Flashcards

e.g. Hepatitis
A subunit contains only the antigens of the microbe that is being vaccinated against. Some vaccines may only contain a specific region of the antigen

What are the advantages and disadvantages of subunit vaccines?

Study These Flashcards

Advantages;
- Antigens cannot become virulent and cause disease
- Easy to store
- Individual cannot infect others
- Can determine whether the person has been vaccinated 
Disadvantages;
- Requires adjuvants and booster doses
- Local reactions at the injection site

What are conjugate vaccines?

Study These Flashcards

e.g. Haemophilus Influenza Type B
Some bacteria possess a polysaccharide coat which disguises its antigens from the immature immune system. A conjugate vaccine contains carrier proteins that are attached to polysaccharides to allow the immune system to recognise them

What are the advantages and disadvantages of conjugate vaccines?

``` Advantages; - Cannot become virulent and cause disease - Easy to store - Individual being vaccinated cannot infect others Disadvantages; - Requires adjuvants and booster doses - Local reactions at injection site - Expensive ```

What is gonorrhoea?

A gram negative, intracellular diplococci

Describe the T spot test

1) Blood sample is centrifuged 2) The middle layer is comprised of Peripheral Blood Mononuclear Cells 3) The sample is diluted and added to wells coated with IFN-γ antibodies 4) Wells are incubated 5) TB codes for proteins; 2 of which are used to challenge the T-cells in the blood 6) If challenged, T cells release IFN-γ 7) When washed with substrate solution the wells have spots at the bottom

Describe the classification of chlamydia

Types D to K cause genital chlamydia, however there are also L types which can cause LGV; an infection of the lymphatics which can lead to many symptoms such as rectocolitis

What treatments are used for chlamydia?

Genital chlamydia - Azithromycin | LGV - 3 weeks of doxycycline

Describe the natural history of syphilis infection

1) Exposure 2) Primary lesion - Chancre (3 weeks) 3) Secondary lesion - Rash (8-16 weeks) 4) Latent syphilis 5) Tertiary syphilis - CVS, neurological etc. (10-40 years)

Describe the treatment used for syphilis

Intra-gluteal injection of Bicillin

Describe the treatment of HSV

Acyclovir - A 5 days course of treatment which requires 5 tablets a day

What is Chronic Granulomatous Disease?

An inherited disorder which tends to be X-linked. This causes a defect in the gene coding for NADPH oxidase and so the patient will have few oxygen radicals and defective intracellular killing. This leads to recurrent bacterial and fungal infections

What are the three phases of infection following a solid organ transplantation?

<1 month - Surgical Infection e.g. E. Coli 1-6 months - Opportunistic Infections e.g. Aspergillus 6 months - Community acquired infection e.g. pneumococcus, listeria, salmonella

Describe the treatment used for neutropenic sepsis

- Pipericillin - Tazobactam - Gentamicin

What is Varicella Zoster?

A herpes virus that causes chicken pox and in the elderly it will cause shingles. In the immunocomprimised it may disseminate e.g. to the eCNS

What is Cytomegalovirus?

A herpes virus which causes a mild illness that may be asymptomatic or glandular fever. In the immunocomprimised this infection will be far more severe with increased risk of bacterial infection

What is Epstein Barr Virus?

A herpes virus that causes infectious mononucleosis in most patients, however in the immunocomprimised, malignant disease can arise

What are adenoviruses?

Adenoviruses are a huge family of viruses that can cause a wide range of complications in the immunocomprimised including hepatitis, nephritis and colitis

What are polyomaviruses?

Around 90% of people will have polyomavirus lying dormant in their urinary tract and kidney, however this doesn't become a problem until we are immunocomprimised, at which point it may cause haemolytic cystitis

What are the two main types of immunodeficiency?

Primary - (Congenital) Resulting from genetic defects which are inherited Secondary - (Acquired) As a result of other diseases or conditions

What are the main types of primary immunodeficiency?

- Humoral defect (50%) - B Cells and antibodies - Combined humoral and cellular immunodeficiencies (20%) - B and T cells - Cell mediated defect (10%) - T cells - Phagocytic dysfunction (18%) - Granulocytes - Complement deficiency (2%)

What are humoral defects? (Immunodeficiency)

A lack of antibodies e.g. - IgA deficiency - Hyper IgM syndrome

What are cell mediated defects? (Immunodeficiency)

T cells fail to provide sufficient signals to the B cells e.g. - Severe Combined Immunodeficiencies (SCID) - A mutation in the cytokine receptors. This causes the T cells and NK cells to fail which means the B cells cannot efficiently produce antibodies

What are phagocytic defects? (Immunodeficiency)

A problem with the number and or functioning of the phagocytes e.g. - Chronic Granulomatous Disease

Clinical Microbiology 2 Flashcards

(45 cards)