The aminoglycosides are bactericidal antibiotics that irreversibly inhibit
protein synthesis and ribosome function.
There are effective against aerobic Gram negative bacilli for example
pseudomonas and hospital acquired Gram negative bacteria.
They have a narrow therapeutic index and need monitoring to detect accumulation
if given intravenously. The main toxicity associated with systemic use
are nephrotoxicity and ototoxicity.
In ophthalmology, only gentamicin and amikacin are commonly used.
Gentamicin is given usually for corneal ulcer in combination with cefuroxime
to cover Gram negative bacilli.
Both gentamicin and amikacin can be given intravitreously for post-operative
endophthalmitis. However, amikacin is preferable as it is less toxic and
therefore a lower incidence of retinal necrosis.
Neomycin is often incorporated with topical steroid drop for post-surgical
use. Neomycin can give rise to contact dermatitis in a significant amount
Fungal infections or mycoses are classified depending on the degree
of tissue involvement and mode of entry into the host. These are:
Superficial - localized to the skin, the hair, and the nails.
Subcutaneous - infection confined to the dermis, subcutaneous
tissue or adjacent structures.
Systemic - deep infections of the internal organs.
Opportunistic - cause infection only in the immunocompromised.
Human fungal infections in the United Kingdom are uncommon in normally
healthy persons, being confined to conditions such as candidiasis (thrush)
and dermatophyte skin infections such as athlete's foot. However, in the
immunocompromised host, a variety of normally mild or nonpathogenic fungi
can cause potentially fatal infections. Furthermore, the relative ease
with which people can now visit "exotic" countries provides the means for
unusual fungal infections to be imported into this country.
Necrotizing fasciitis results from infection of the soft tissue below
the dermis, spreading with alarming rapidity along the facial planes causing
disruption of the blood supply hence necrosis and gangrene This infection
is caused mainly by Streptococcus pyogenes (B-haemolytic Group A) and micro
aerophilic Streptotococci with anaerobic bacteria.
The patient is usually in a toxic shock state necessitating rapid action
in terms of antibiotic treatment which should be intravenous Benzyl Penicillin
and Clindamycin with or without Metronidazole, in addition to tissue debridment.
This situation usually follow trauma to the skin such as wounds after surgery.