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HAEMOPHILUS TEST MEDIUM HTM BASE
Code: CM0898
A medium specifically formulated for the susceptibility testing of Haemophilus influenzae.
Typical Formula* | gm/litre |
Mueller-Hinton Agar | 38.0 |
Yeast extract (specifically selected for low antagonist levels) | 5.0 |
pH 7.3 ± 0.1 @ 25°C |
* Adjusted as required to meet performance standards
HTM SUPPLEMENT
Code: SR0158
Vial contents (each vial is sufficient for 500ml of medium) | per vial | per litre |
NAD | 7.5mg | 15.0mg |
Haematin | 7.5mg | 15.0mg |
DirectionsSuspend 21.5g of Haemophilus Test Medium Base in 500ml of distilled water. Bring to the boil to dissolve. Sterilise by autoclaving at 121° C for 15 minutes. Cool to 50°C and aseptically add the contents of 1 vial of Haemophilus Test Medium Supplement SR0158, as directed. Mix well and pour into sterile Petri dishes.
DescriptionHaemophilus Test Medium (HTM) has been specifically formulated for the susceptibility testing of Haemophilus influenzae. The medium forms part of the recommended methods of the United States National Committee for Clinical Laboratory Standards (NCCLS)1.
Haemophilus influenzae require complex media for growth. These complex media have aggravated the routine susceptibility testing of Haemophilus influenzae because of antagonism between some essential nutrients and certain antimicrobial agents. Difficulties in interpreting inhibition zones may also arise.
Oxoid Haemophilus Test Medium (HTM) is based on the formulation developed by Jorgensen et al.2 which is now recommended by the United States NCCLS. The results achieved using HTM have been found to be highly reproducible3,4. Comparisons with Mueller-Hinton Chocolate Agar have shown an overall agreement of 99.6%5.
The transparency of the medium allows zones of inhibition to be read easily through the bottom of the Petri dish. HTM contains low levels of antimicrobial antagonists, which allows testing of trimethoprim/sulphamethoxazole to be carried out with greater confidence.
Technique1 Prepare the inoculum in Mueller-Hinton Broth CM0405 or 0.9% saline, to match the turbidity of 0.5 McFarland standard.2 Using a swab saturated with the above inoculum suspension, inoculate the surface of a Haemophilus Test Medium Agar plate to give confluent growth.3 Apply the antimicrobial discs on to the surface of the Haemophilus Test Medium plate.4 Incubate the plates at 35°C in 5-7% carbon dioxide for 16-18 hours and measure the zones of inhibition.NB: In the absence of a CO2 incubator, the CO2 enriched atmosphere can best be achieved by using the Oxoid Gas Generating Kit BR0039 in conjunction with Oxoid Anaerobic Jar or alternatively use CO2Gen CD0025.
Storage conditions and Shelf lifeStore the dehydrated medium at 10-30°C and use before the expiry date on the label.Store the prepared plates of medium at 2-8°C.HTM Supplement as supplied should be stored in the dark below 0°C. When stored as directed the supplement is stable until the expiry date stated on the label.
AppearanceDehydrated medium: Light straw coloured, free-flowing powderPrepared medium: Straw coloured gel
