Frequently Asked Questions

Both contain identical MacConkey Agar formulation. The 50-plate pack (MPH081-50PT) offers: (1) Lower cost per plate for high-volume users, (2) Reduced ordering frequency, (3) Consistent lot numbers across more tests, Choose 50-plate packs for: routine daily testing, high-throughput food/Water labs, environmental monitoring programs with many sample points. Choose 20-plate packs for: low-medium volume testing, limited storage space, shorter shelf-life needs, or when testing multiple media types.

Yes, MacConkey is commonly used for environmental monitoring to detect gram-negative bacteria in cleanrooms, Water systems, and non-sterile manufacturing areas. It helps identify contamination from personnel (fecal coliforms), Water sources (Pseudomonas, coliforms), or biofilm formation. For pharmaceutical EM programs, use MacConkey in combination with TSA (total aerobes), SDA (fungi), and Mannitol Salt Agar (Staph). Incubate and read per your validated SOP. Document negative results or investigate positive findings.

Yes, HiMedia MacConkey Agar RTU is manufactured to meet specifications for FDA Bacteriological Analytical Manual (BAM), AOAC Official Methods, ISO standards, and USP requirements. Each lot is performance-tested with ATCC reference strains (E. coli ATCC 8739 for lactose fermentation, and Staphylococcus aureus ATCC 6538 ). Certificates of Analysis document compliance with method specifications. Widely used in food, pharmaceutical, and microbiology laboratories.

RTU Mac Conkey Agar plates eliminate: (1) 2-3 hours media preparation time, (2) Autoclaving requirements, (3) Plate pouring and cooling, (4) QC testing of each batch prepared, (5) Contamination risk during preparation, (6) Batch-to-batch variability from manual preparation. RTU plates arrive pre-poured, sterilized, QC-tested with guaranteed performance. Ideal for labs with limited prep facilities, GMP requirements, or inconsistent in-house media quality. Cost-effective for low-medium volume testing.

Store MacConkey RTU plates at 20-25°C in original sealed packaging protected from light. Shelf life is typically 3-6 2-4 months from manufacture date. Do not freeze. Before use, allow plates to equilibrate to room temperature and check for: (1) No contamination, (2) No excessive moisture on agar surface, (3) Pink color maintained, (4) No cracks or shrinkage. Inspect expiration date on each sleeve. Discard plates showing dryness, discoloration, or contamination.

MacConkey supports gram-negative bacteria: Lactose fermenters (pink): E. coli, Klebsiella pneumoniae, Enterobacter spp., Citrobacter spp. Non-lactose fermenters (colorless): Salmonella spp., Shigella spp., Proteus spp., Pseudomonas aeruginosa, Yersinia spp. Gram-positive bacteria (Staphylococcus, Streptococcus, Bacillus, Enterococcus) are inhibited by bile salts and crystal violet. Some gram-positive organisms may show minimal growth but are easily distinguished.

Incubate MacConkey Agar at 30-35°C for 18-72 hours aerobically. For growth promoting incubate for >=18 hours, for characteristic colonies incubate for 18-72 hours. For inhibitory properties check for >=72 hours. For Water testing, some protocols use 30-35°C. For food testing, follow specific method requirements (FDA BAM, AOAC, ISO). Check colonies after 18-24 hours for optimal differentiation.

MacConkey Agar contains neutral red, pH indicator that turns pink under acidic conditions. Lactose-fermenting bacteria (E. coli, Klebsiella, Enterobacter) ferment lactose producing acid, which lowers pH and turns colonies and surrounding medium pink/red. Non-lactose fermenters (Salmonella, Shigella, Pseudomonas) produce colorless colonies. The medium itself is pale pink due to the neutral red. This differential property allows rapid presumptive identification of enteric pathogens.

MacConkey Agar i recommended for selective isolation and differentiation of E.coli and other enteric bacteria from pharmaceutical products in accordance with the microbial limit testing by harmonized methodology of USP/EP/BP/JP. It selectively inhibits gram-positive bacteria using bile salts and crystal violet, while differentiating lactose-fermenting bacteria (appear pink/red) from non-lactose fermenters (appear colorless/pale).

HiCrome UTI Agar is chromogenic medium for rapid identification of urinary tract infection (UTI) pathogens from urine specimens. Different organisms produce characteristic colony colors: E. coli (pink/magenta), Klebsiella/Enterobacter (blue), Proteus (brown), Enterococcus (turquoise), Staphylococcus (white/cream), Pseudomonas (cream/colorless), Candida (white). Allows simultaneous detection and differentiation in mixed cultures. Enables presumptive identification in 24 hours vs 48-72 hours with traditional methods. Used in clinical microbiology for urine culture. Reduces need for biochemical confirmation in many cases.

Bacillus cereus causes two types of foodborne illness: (1) Diarrheal syndrome - toxin produced in intestine, symptoms 8-16 hours, from protein-rich foods, (2) Emetic syndrome - toxin pre-formed in food (cereulide), symptoms 1-5 hours, from rice dishes, pasta. Spores survive cooking, germinate during cooling. Rapid growth at room temperature produces toxin. FDA action level: >10^5 CFU/g considered hazardous. Common in rice, pasta, dairy, vegetables, meat. Testing required for outbreak investigations and HACCP verification.

HiCrome Bacillus Agar is a chromogenic medium for isolation and differentiation of Bacillus species from food, pharmaceutical, and environmental samples. Different Bacillus species produce characteristic colony colors due to species-specific enzyme activities. B. cereus produces blue-green colonies. Other Bacillus species produce cream, pink, or purple colonies. More selective than standard Bacillus selective media (MYP, PEMBA). Applications: (1) Food testing for B. cereus (food poisoning), (2) Pharmaceutical environmental monitoring, (3) Spore testing, (4) Probiotic product QC.

While HiCrome offers rapid coliform/E. coli detection, EPA-approved methods for drinking Water compliance monitoring are: Standard Methods 9221/9222, EPA Method 1603 (membrane filtration), Colilert-18 (IDEXX). HiCrome is excellent for: (1) Non-compliance monitoring, (2) Screening and research, (3) Process Water testing, (4) Swimming pool Water, (5) Food factory Water. For regulatory drinking Water reporting, use EPA-approved methods. HiCrome provides faster results for internal monitoring and troubleshooting Water treatment issues.

HiCrome Coliform Agar is a chromogenic medium for simultaneous detection and differentiation of total coliforms and E. coli in Water, food, and pharmaceutical samples. E. coli produces dark blue to violet colonies (beta-glucuronidase activity). Other coliforms produce pink to red colonies (beta-galactosidase activity). Non-coliform bacteria are inhibited or produce colorless colonies. One plate provides: total coliform count + specific E. coli count. Saves time and materials vs traditional multiple-tube MPN or membrane filtration with confirmations. The composition and performance criteria of this medium are as per the specifications laid down in ISO 9308-1:2014/Amd 1:2016.

The medium contains chromogenic substrates and sorbitol. E. coli O157:H7: cannot ferment sorbitol, produces mauve/purple colonies. Other E. coli: ferment sorbitol producing acid, appear blue-green. The chromogenic substrate is cleaved by beta-glucuronidase enzyme present in most E. coli but absent in O157:H7, providing additional differentiation. Tellurite provides selectivity against non-E. coli. This allows rapid screening; purple colonies are presumptive O157:H7 requiring confirmation by serology (O157 antigen) and molecular testing (Shiga toxin genes).