Combi 90- OD291-1PK is 8-in-one multi disc, an octo disc, supplied by HiMedia. It contains an inert flat circular octa ring with 8 equidistant arms on the outer periphery, each arm having a 6mm disc. Each disc is satured with a specific antibiotic, that help in antibiotic susceptibility testing (AST) of Gram positive bacteria. Each antibiotic disc is about 24mm apart from the adjacent disc, and is labeled with the concentration and symbol of the respective antibiotic. OD291 octa rings can be used on 120 mm media plates. The composition of antibiotics on the discs are as:

Ampicillin (AMP) 10g

Levofloxacin (LE) 5g

Vancomycin (VA) 30g

Cephalothin (CEP) 30g

Gentamicin (GEN) 10g

Oxacillin (OX) 1g

Clindamycin (CD) 2g

Erythromycin (E) 15g

The Combi 90-OD291 rings are deposited aseptically in the center of the inoculated Mueller Hinton agar plate using sterile forceps. Immediately the plates are incubated at 352C for 16-18 hours. For fastidious organisms, incubate at appropriate temperature and time. The diameter of the zones of complete inhibition are measured to the nearest mm.

These multidiscs are convenient and economic for conducting AST. They give the priviledge to study large number of antibiotics at one time.

The Combi 90-OD291 discs should be stored at -20C under dry conditions, along with the dessicator provided in indivisual pack.