Overview:
MSRV is currently the most sensitive and rapid selective motility-enrichment medium for the detection of Salmonella spp. (including S. Typhi and S. Paratyphi) from foods, feeds, and environmental samples. It is the official reference method in ISO 6579-1:2017 (all parts), EU Regulation 2073/2005, and many national standards. The semi-solid consistency allows motile Salmonella to migrate outwards from the inoculation drop, forming a characteristic halo within 24�48 h.
Applications:
Primary detection method after non-selective pre-enrichment (BPW)
Official ISO 6579-1 method (parallel with RV/SC/MKTTn)
Especially effective for low-level contamination and stressed cells
Preferred in high-throughput food laboratories worldwide
Key Features:
Extremely low selective agent concentration + novobiocin ? excellent resuscitation
Motile Salmonella swarm 20�40 mm from inoculation point
Non-motile or inhibited organisms stay at the central spot
Very high sensitivity (>98 %) and few false positives
Composition (per liter � modified base):
Tryptose / Casein Peptone 4.6 g
NaCl 7.3 g
KH?PO? 1.5 g
MgCl?�6H?O 10.7 g
Malachite Green oxalate 0.036 g
Agar (technical, high gel strength) 2.7 g
Final pH: 5.2 � 0.2 at 25 �C
Selective Supplement (added after autoclaving, at 45�50 �C):
Novobiocin 20 mg/L (filter-sterilized)
Preparation:
Suspend 26.836 g dehydrated base in 1 L purified water.
Heat with agitation and boil for 1�2 min until completely dissolved.
DO NOT AUTOCLAVE (malachite green is heat-labile).
Cool to 45�50 �C.
Aseptically add 20 mg filter-sterilized novobiocin.
Dispense 10 mL into sterile 90 mm plates (? 0.5 cm depth) or 3-drop method on pre-poured plates.
Procedure (ISO 6579-1):
After 16�20 h BPW pre-enrichment
Drop 3 � 10 �L (or single 20�50 �L) onto surface of MSRV plate
Incubate 41.5 � 1 �C for 2 � 24 h
Read after 24 h and 48 h
Positive = grey-white, turbid, migratory halo ? 20 mm from inoculation point
Subculture from edge of migration zone onto XLD, BGA, or chromogenic agar
Storage:
Prepared plates: 2�8 �C in sealed bags, protected from light, use within 7 days.
For food and environmental microbiology only.
Reference: De Smedt & Bolderdijk (1987, 1990), ISO 6579-1:2017 + Amd.1:2020.