ToB S4 - Bacteria and Viruses Flashcards Preview

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Flashcards in ToB S4 - Bacteria and Viruses Deck (19)
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What is infection?

The multiplication of a pathogen microbe on/in a susceptible host with associated dysfunction/damage


Outline the Henle-Koch’s Postulates

Proving the bacteria is the causation of the disease

1) Agent must be shown to be present in every case of the disease by isolation in pure culture

2) The agent must not be found in cases of other diseases

3) Once isolated, the agent must be capable of reproducing the disease in experimental animals, and must be recovered from the experimental disease produced


What colour do gram positive bacteria stain?



What colour do gram negative bacteria stain?



Explain the significance of genome composition when classifying and detecting viruses

RNA viruses are more likely to mutate as RNA is less stable


Explain the terms Pathogen and Non-Pathogen

A pathogen is a bacterium, virus, or other microorganism that can cause disease whereas a non-pathogen is a bacterium that doesn’t cause disease. Many non-pathogens perform essential ecological roles


Why is acid fast staining used?

- Allow us to detect the bacteria causes of tuberculosis and leprosy (mycobacteria)

- These bacteria cannot be identified by gram staining


Explain the significance of envelope presence when classifying and detecting viruses

If a virus has an envelope it's more easily sterilised as if holes are punched in the envelope the virus cannot survive


Explain the significance of Replication strategy when classifying and detecting viruses

RNA viruses can use reverse transcriptase (HIV), DNA viruses can use cell machinery (HPV), or a virus can carry its own replication enzymes


Name a DNA enveloped Virus

Any from: - Hepatitis B - Inflamed liver - Herpes - Oral/genital warts - Smallpox - smallpox


Name a DNA non-enveloped virus

HPV - Warts, cervical cancer


Name a RNA enveloped virus

Any from: - HIV - AIDS - Rubella - Rash, congenital rubella syndrome - Rotovirus - Diarrhoea - Coronavirus - SARS


Gram positive bacteria?

Staphylococcus, streptococcus and Clostridium


(Gram negative = everything else Acid fast - mycobacterium)


What is the target for the β -lactams class of antibiotics? Eg Amoxicillin, Penicillin

Cell wall


What is the target for the glycopeptide class of antibiotics? Eg Vancomycin

Cell wall


What is the target for the macrolide class of antibiotics? Eg Erythromycin

Protein synthesis


Define "carriage" in the context of infection

Passage taken by microorganism


Define "normal flora" in the context of infection

non-pathogenic bacteria naturally found in our bodies e.g. the gut


Define "Commensal" in the context of infection

Symbiotic relationship where one species derives benefit (microbe) and the other is unaffected (host). This is the time when the microbe may be replicating or waiting for the immune system to become compromised