Question

3. Look up the Gram reaction and morphology of the following four organisms and type the information next to each organism below.

1. Bacillus cereus –
2. Escherichia coli –
3. Pseudomonas aeruginosa –
4. Staphylococcus aureus –

4. In your own words, explain the difference between a broad-spectrum and a narrow-spectrum antibiotic.

Answer 1

3)

(A)

Bacillus cereus --> Gram positive, bacilli

(B)

E.coli --> Gram negative, rods

(C)

P. aeruginosa --> Gram negative, rods

4)

​​​​​​Broad spectrum antibiotics are those that act on wide range of disease causing pathogens or act on the major groups of bacteria, gram positive and gram negative.

Nerrow spectrum antibiotics are those that act on either of the group, gram negative or gram positive. For example, penicillin only act on gram positive bacteria effectively.

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