Overview:
Campylobacter Enrichment Broth Base (Preston) is a selective liquid enrichment medium formulated for the resuscitation and selective cultivation of thermophilic Campylobacter species, such as C. jejuni and C. coli, from low-contamination specimens like food, dairy, and clinical fecal samples. Originally described by Bolton and Robertson in 1982, it uses a nutrient-rich basal broth (peptone and beef extract for amino acids, vitamins, and minerals) supplemented with lysed horse blood for growth factors and the Preston selective supplement (containing polymyxin B, trimethoprim, rifampicin, and cycloheximide) to inhibit Gram-negative competitors (e.g., Proteus, E. coli), Gram-positive bacteria, and fungi. A pre-enrichment step at 37�C for 4 hours without full antibiotics aids recovery of sublethally injured cells, followed by microaerophilic incubation (5% O?, 10% CO?) at 42�C for 18-48 hours, resulting in turbid growth. This medium complies with APHA and ISO 10272 standards for enhancing detection in enrichment protocols.
Applications:
?? Selective enrichment of Campylobacter jejuni and C. coli from poultry, meat, milk, and water samples in food microbiology per FDA-BAM and ISO 10272
?? Recovery from clinical fecal specimens or rectal swabs for diagnosing campylobacteriosis (gastroenteritis)
?? Pre-enrichment of stressed or low-count pathogens from environmental sources like sewage or animal feces
?? Subculture prior to plating on selective agars (e.g., mCCDA or Skirrow) for isolation and confirmation
Key Features:
?? Nutrient-rich base with pre-enrichment option supports >90% recovery of injured ATCC strains like C. jejuni 29428 under microaerophilic conditions
?? Preston supplement provides targeted antimicrobial inhibition (polymyxin B for Gram-negatives, rifampicin for Proteus, cycloheximide for fungi) without overly suppressing Campylobacter
?? Lysed horse blood addition neutralizes oxygen toxicity and supplies essential hemin and NAD factors for fastidious growth
?? Validated in APHA and EU protocols; optional glycerol in incubation jar prevents swarming
?? Clear to cherry-red solution post-supplementation; turbidity indicates positive enrichment after 48 hours at 42�C
Composition (per liter):
Peptone (or Pancreatic Digest of Animal Tissue) � 10.0 g
Beef Extract (or HM Peptone B equivalent) � 10.0 g
Sodium Chloride (NaCl) � 5.0 g
Lysed Horse Blood � 50.0 mL
Preston Selective Supplement: Polymyxin B � 2,500 IU; Trimethoprim � 5 mg; Rifampicin � 5 mg; Cycloheximide � 50 mg
Final pH: 7.5 � 0.2 at 25�C
Preparation:
Suspend 25.0 g of the dehydrated base in 945 mL of purified/distilled water. Heat gently with agitation if necessary until completely dissolved (do not boil excessively). Autoclave at 121�C (15 psi) for 15 minutes. Cool to 45-50�C in a water bath. For pre-enrichment (optional but recommended for stressed cells): Aseptically add 50 mL sterile lysed horse blood and inoculate sample, then incubate at 37�C for 4 hours without full supplement. After pre-enrichment, add the rehydrated Preston supplement (two vials per liter, each in 2.5 mL sterile water). Mix well and dispense into tubes or flasks (e.g., 10 mL per 1 g sample). Incubate under microaerophilic conditions (5% O?, 10% CO?, 85% N?) at 42�C for 18-48 hours. Prepared broth should appear light yellow and clear basally, becoming cherry-red and opaque after blood addition.
Storage:
Dehydrated medium: Store in a tightly closed container at 10�30�C, protected from moisture, light, and humidity; stable until expiry date (typically 3 years). Once opened, recap tightly to prevent lump formation due to hygroscopic nature.
Prepared broth: Store at 2�8�C in sealed containers; use within 24 hours post-supplementation or discard. Avoid freezing; discard if turbid without inoculation, contaminated, or pH shifts.
?? For laboratory and research use only. Not for diagnostic procedures without proper validation. Not for human or veterinary consumption. Handle under biosafety level 2; use Universal Precautions�wear gloves, eye protection, and lab coat. Autoclave all waste and contaminated materials before disposal. Microaerophilic incubation required; suboptimal conditions may reduce recovery. Not suitable for non-thermophilic Campylobacter without adjustments.3.7s