Question

If the babies were diagnosed with a penicillinase resistant strain, what would be an appropriate drug choice to treat them?

Unlike this case, many times, Staph. aureus cannot be isolated from the site of skin damage in patients. Why might this be? (consider how the damage is caused)

Answer 1

Answer 1

1. Penicillins are antibiotics that have a Beta-lactam ring in it.
2. The antibacterial activity of the drug is due to the Beta-lactam ring
3. The Beta-lactam ring binds to the DD-transpeptidases of the bacteria
4. This prevents cross-linking in the bacterial wall
5. The bacterial wall is prevented from forming
6. No wall means no protection from the outside water and solute pressure ( osmosis)
7. Bacteria have evolved certain defense mechanisms to protect themselves from Beta-lactam.
8. Bacterias produce penicillinase which breaks down the Beta-lactam ring of the penicillin drug.
9. As a result, the drug has no anti-microbial activity
10. However, certain penicillins are resistant to penicillinases. They are:
    1. Cloxacillin
    2. Oxacillin
    3. Dicloxacillin
    4. Methicillin
11. In this clinical case, the pathogen is resistant to methicillin - Most likely methicillin-resistant staphylococcus aureus
12. The drugs active against MRSA are -
    1. Vancomycin (glycopeptide)
    2. Teicoplanin (glycopeptide)
    3. Linezolid (Oxazolidinone)
    4. Clindamycin (Licosamide)
    5. Daptomycin (Lipopeptide)
    6. Ceftobiprole, ceftaroline (cefalosporin)
    7. Cotrimoxazole
    8. Rifampicin
    9. Tigecycline

It is difficult to isolate Staphylococcus aureus because:

1. if the sample is collected without disinfecting the site - this can lead to the growth of commensals
2. if the sample is not transported properly to the lab
3. If the sample is not representative of the infection.
4. If the sample is adequate
5. if samples were collected after starting antibiotics.
6. Outdated culture media or defective culture media is used
7. If improper lab techniques are followed.
8. Wrong labelling