Page 74 - MNU microbiology theoritical 2025

General Microbiology & Immunology (PM 401) Second level Semester 4 2024/2025

Advantages

• The method is easy to use, relatively fast, and inexpensive

Disadvantages

• only relatively high concentrations of bacteria may be enumerated.

• It does not necessarily yield an accurate count; the method cannot distinguish

living from dead bacteria

2- Plate Count
• The viable plate count is a count of viable or live cells.

• It is based on the principle that viable cells replicate and give rise to visible

colonies when incubated under suitable conditions for the specimen.

• Colonies count = number of cells in the initial sample

• Counts are expressed as Colony-Forming Units

• There are two common approaches to inoculate plates for viable counts:

➢ pour plate method

➢ spread plate method

General Microbiology & Immunology (PM 401) theoretical handbook Page 63