SUPERIOR CAMPYLOBACTER ISOLATION FROM LAB M
The excellent reputation of LAB M¹s Campylobacter Enrichment Broth has been
further re-enforced by the FDA¹s inclusion of the product in its new BAM
manual. Acknowledged as a superior selective enrichment medium, the broth
provides an essential starting point for the successful recovery and
isolation of Campylobacter spp.
Campylobacter isolation poses a problem for many laboratories and recovery
rates can be disappointing. Several factors may contribute to the problems,
and it can be particularly difficult to isolate organisms which have been
sub-lethally damaged by food processing or are present in very small numbers
or in heavily contaminated specimens.
Formulated by internationally recognised Campylobacter expert Professor Eric
Bolton, Public Health Laboratory Service UK, the LAB M medium successfully
overcomes these problems and offers significant improvements over
traditional Preston Broth. Contaminating organisms are suppressed whilst
Campylobacter spp. are Œnurtured¹ in ideal culture conditions.
Subculture onto LAB M¹s Campylobacter Blood Free Selective Medium further
improves recovery, allowing incubation at 37ƒ C, which is reported as
offering a higher rate of recovery than 42ƒ C incubation.
Suitable for food, environmental and faeces samples, Campylobacter
Enrichment Broth is supplied as a dehydrated powder and lyophilised
supplement. Prepared medium in capped bottles is stable for 7 days when
stored at 2-8ƒ C.
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Editor: For more information, please contact: Phil Smith, IDG UK Ltd,
Topley House, 52 Wash Lane, Bury, Lancs, BL9 6AU, Phone: 0161 797 5729,
Fax:0161 762 9322
Email: pasmith at idgplc.com
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SALMONELLA ISOLATION AS EASY AS ABC!!
IDG has introduced a new chromogenic agar, under the LAB M brand, for
selective isolation of Salmonella spp. Demonstrating superior sensitivity
and specificity to desoxycholate citrate agar (DCA), the new ABC medium
(Freeman formulation) can significantly reduce the labour time and costs
associated with Salmonella detection using traditional agars.
Isolation of Salmonella spp. by culture remains the gold standard method of
detection. However most media are highly non-specific, and consequently
place a heavy burden on the laboratory in terms of biochemical and
serological confirmation of suspect colonies.
With improved specificity, the new ABC medium dramatically reduces the need
for Œfalse positive¹ screening, saving labour and reducing consumable costs.
ABC medium incorporates two chromogenic substrates which exploit the fact
that Salmonella spp. can be distinguished from other Enterobacteriaceae by
the presence of
a-galactosidase activity in the absence of b-galactosidase activity.
CHE-Galactoside is utilised by most Enterobacteriaceae, yielding black
colonies. The X-µ-Gal is hydrolysed by Salmonella spp. to produce
characteristic, easy to distinguish, green colonies.
A recent study, using the LAB M formulation, examined 1,022 strains of
Salmonella spp, and 300 other Gram negative strains. 99.7% of Salmonella
spp. produced typical green colonies on ABC medium and only one false
positive reaction was seen.
283 stool samples, selectively enriched in selenite broth were also
sub-cultured onto DCA and ABC medium. Overall, the sensitivity and
selectivity were clearly superior for ABC medium (100 and 90.5%,
respectively) than for DCA (88 and 26.9% respectively) as indicated in the
table below.
283 samples ABC DCA
Sensitivity 100 % 88 %
Selectivity 90.5 % 26.9 %
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Editor: For more information, please contact: Phil Smith, IDG (UK) Ltd,
Topley House, 52 Wash Lane, Bury, Lancs, BL9 6AU,
Phone: +44 (0) 161 797 5729, Fax: +44 (0) 161 762 9322 Email:
pasmith at idgplc.com
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IMPROVED ISOLATION OF LISTERIA SPP
IDG has introduced a new selective medium under its LAB M brand for improved
isolation of Listeria spp. Utilising a novel specific substrate for the
detection of glucosidase activity, Harlequin” Listeria medium has proved
superior to Oxford formulations, with significantly improved isolation rates
(34%) and clearer differentiation of colonies.
Listeria spp. have again been implicated in a number of high profile cases
of food poisoning, leading to the recall of a wide range of contaminated
products. The risk to health from infection can be very serious, with
symptoms covering the full spectrum from a flu-like illness and diarrhoea,
to meningitis, septicaemia and death. The financial implications for the
food industry of an outbreak or product recall are also severe, increasing
the need for comprehensive product testing.
Harlequin ” Listeria Medium offers a simple and effective plating system,
introducing significant benefits to the microbiologist. Confidence in
testing is improved; positives can be detected earlier and with easy
identification of colonies, plates can be screened faster. The medium
utilises the same selective antibiotic supplement as the Oxford formulation,
but the incorporation of a specific chromogen, CHE-glucoside, is
incorporated to detect b-glucosidase. Cleaving of the substrate releases an
insoluble black pigment that is retained within the colony, unlike Oxford
medium where it diffuses into the surrounding medium.
The intense black coloration against a clear agar, makes screening for
suspect colonies very easy and a reduced concentration of antibiotic
improves recovery. In a recent study, the isolation rates of Oxford
formulation and the new medium were compared.
Harlequin ” Listeria Medium gave a 34% increase in the isolation of Listeria
spp. with 85% of positives detectable after 22 hrs incubation.
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Editor: For more information, please contact: Phil Smith, IDG UK Ltd, Topley
House, 52 Wash Lane, Bury, Lancs, BL9 6AU, Phone: 0161 797 5729, Fax: 0161
762 9322
Email: pasmith at idgplc.com
