What is the principle of typing bacteria?
THE PRINCIPLES OF BACTERIAL TYPING. A typing method is defined as any method that can be used. to differentiate bacteria beyond species level. The essence. of the use of typing methods is to be able to compare isola-
Why is phage typing important?
Using phages to differentiate bacteria is referred to as phage typing. Phage typing can be extremely important in many health situations because it can identify random, unrelated organisms as well as the isolates that are actually responsible for a given problem.
What is the principle behind plaque formation in the bacterial plates?
The plaque assay (Figure 2) is based on incorporation of host cells, preferentially in log-phase growth, into the medium. This creates a dense, turbid layer of bacteria able to sustain viral growth. An isolated phage can subsequently infect, replicate within, and lyse one cell.
What is phage typing in Salmonella?
Phage typing provides a rapid, accurate, and cheap method of investigating Salmonella strains for epidemiological use. Salmonella strains within a particular serovar may be differentiated into a number of phage types by their pattern of susceptibility to lysis by a set of phages with different specificity.
What is typing method in microbiology?
Molecular typing is a way of identifying specific strains of microorganisms, such as bacteria or viruses, by looking at their genetic material. It is mainly used to pinpoint the source of foodborne outbreaks. It can also be used to identify which microorganisms are: Most virulent and cause serious diseases.
What valuable information does phage typing provide?
Phage typing is still used to identify and distinguish different strains within a given species when isolated from different origins (disease, food, water, environmental) or geographical locations.
Why is it best to use as many phage types as possible in a phage typing exercise?
Why is it best to use as many phage types as possible in a phage typing exercise? The greater the number of phages, the better chance that the correct phage for the bacterium will be used and the bacterium identified.
How do you detect phage?
Polymerase chain reaction (PCR) is a simple and robust method to verify the presence of phages faster than plaque assays, based on the detection of nucleic acid.
What is the principle of plaque assay?
During a plaque assay, a confluent monolayer of host cells is infected with a lytic virus of an unknown concentration that has been serially diluted to a countable range, typically between 5-100 virions.
What is a genotypic method?
Genotypic Methods. The genotypic methods access the genetic elements from chromosomal and/or extra-chromosomal DNA allowing differentiation among close related strains. They include multiple gel electrophoresis and sequence-based techniques (Sabat et al., 2013; Ngoi et al., 2015).
What are different typing methods of microorganisms?
Commonly used molecular tying methods are as follows: Multilocus sequence typing (MLST) Multilocus variable-number tandem repeat analysis (MLVA) Pulsed-field gel electrophoresis (PFGE) PCR Ribotyping (agarose based or sequence-based)
What is phage typing quizlet?
what is phage typing? Used to classify strains within species of bacteria, each strain is sensitive to a small number of different phages (*what kind of viruses are bacteria susceptible to?) phage typing. Varying bacterial strains produce specific plaque patterns when infected with bacteriophage.
Why is it best to use as many phage types as possible in a phage typing exercise quizlet?
How do you calculate titre of phage?
To calculate the titer (the concentration of phage in the lysate, measured in plaques per ml), multiply back up based on the dilution of the spot. The number of plaques per ml calculated is the titer (concentration of PFU/ml).
What is bacteriophage plaque assay?
He defined the plaque assay for quantitating bacteriophage, a technique to enumerate virus particles based on their ability to kill cultured cells and therefore produce holes, or plaques in the cell layer that became a keystone for defining the properties of viruses.
Why is agar needed in a plaque assay?
This assay is based on a microbiological method conducted in a plate. Specifically, a confluent monolayer of host cells is infected with the virus at varying dilutions and covered with a semisolid medium, such as agar, to prevent the virus infection from spreading indiscriminately.
Why use CFU ml instead of cells?
Unlike in direct microscopic counts where all cells, dead and living, are counted, CFU measures viable cells. By convenience the results are given as CFU/mL, colony-forming units per milliliter.
What is phage typing?
Phage typing is a rapid and low-cost approach for the epidemiological surveillance and outbreak investigation (identification of the source of infection).
What is the size of the culture culture for phage typing?
The culture is 10cm in diameter. Phage typing is a phenotypic method that uses bacteriophages (“phages” for short) for detecting and identifying single strains of bacteria. Phages are viruses that infect bacteria and may lead to bacterial cell lysis.
What is the difference between Phage typing and whole genome sequencing?
The bacterial strain is assigned a type based on its lysis pattern. Phage typing was used to trace the source of infectious outbreaks throughout the 1900s, but it has been replaced by genotypic methods such as whole genome sequencing for epidemiological characterization.
What is a clear zone in phage typing?
Phages which are able to set up a lytic infection in that isolate produce a clear zone. As the ability to be infected (and lysed) by different phages varies between different strains of bacteria, the pattern of lysis forms the basis of phage typing.