Amikacin Antimicrobial Susceptibility Discs

£14.83

Amikacin Antimicrobial Susceptibility Discs

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Description

Amikacin is an antibiotic used for a number of bacterial infections. This includes joint infections, intra-abdominal infections, meningitis, pneumonia, sepsis, and urinary tract infections. It is also used for the treatment of multidrug-resistant tuberculosis. It is most often used for treating severe infections with multidrug-resistant, aerobic Gram-negative bacteria, especially Pseudomonas, Acinetobacter, Enterobacter, E. coli, Proteus, Klebsiella, and Serratia. The only Gram-positive bacteria that amikacin strongly affects are Staphylococcus and Nocardia.Amikacin can also be used to treat non-tubercular mycobacterial infections and tuberculosis (if caused by sensitive strains) when first-line drugs fail to control the infection. It is rarely used alone.

Amikacin irreversibly binds to 16S rRNA and the RNA-binding S12 protein of the 30S subunit of prokaryotic ribosome and inhibits protein synthesis by changing the ribosome’s shape so that it cannot read the mRNA codons correctly. It also interferes with the region that interacts with the wobble base of the tRNA anticodon. It works in a concentration-dependent manner, and has better action in an alkaline environment.

At normal doses, amikacin-sensitive bacteria respond within 24–48 hours.

Amikacin evades attacks by all antibiotic-inactivating enzymes that are responsible for antibiotic resistance in bacteria, except for aminoacetyltransferase and nucleotidyltransferase. This is accomplished by the L-hydroxyaminobuteroyl amide (L-HABA) moiety attached to N-1 (compare to kanamycin, which simply has a hydrogen), which blocks the access and decreases the affinity of aminoglycoside-inactivating enzymes. Amikacin ends up with only one site where these enzymes can attack, while gentamicin and tobramycin have six.

Bacteria that are resistant to streptomycin and capreomycin are still susceptible to amikacin; and bacteria that are resistant to kanamycin have varying susceptibility. Resistance to amikacin also confers resistance to kanamycin and capreomycin.

Resistance to amikacin and kanamycin in Mycobacterium, the causative agent of tuberculosis, is due to a mutation in the rrs gene, which codes for the 16S rRNA. Mutations such as these reduce the binding affinity of amikacin to the bacteria’s ribosome. Variations of aminoglycoside acetyltransferase (AAC) and aminoglycoside adenylyltransferase (AAD) also confer resistance: resistance in Pseudomonas aeruginosa is caused by AAC(6′)-IV, which also confers resistance to kanamycin, gentamicin, and tobramycin, and resistance in Staphylococcus aureus and S. epidermidis is caused by AAD(4′,4), which also confers resistance to kanamycin, tobramycin, and apramycin. Some strains of S. aureus can also inactivate amikacin by phosphorylating it.

Please note that these are not a universal fitting and only work in our convenient Disk Dispenser available from here

Our Material Data Sheet can be viewed here

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