Bacterial Infection Quantification
Bacterial Infection Quantification - Related Videos
03:52
Quantification of Bacterial Load in Mouse Spleen and Liver After Systemic Infection
0 Views •
2026
Source: Ahn, J. J., et al. Experimental Infection with Listeria monocytogenes as a Model for Studying Host Interferon-γ Responses. J. Vis. Exp. (2016)The video demonstrates bacterial load measurement in spleen and liver tissues isolated from mice infected with an intracellular bacterial pathogen. Bacteria, accumulated within tissue-resident phagocytes during systemic infection, are released using detergent-based lysis and mechanical disruption. Serial dilutions of the homogenates are plated on...
02:42
Quantification of Tissue Bacterial Load in a Mouse Model of Chronic Intestinal Infection
0 Views •
2026
Source: Lo, B. C., et al. Chronic Salmonella Infection Induced Intestinal Fibrosis. J. Vis. Exp. (2019)The video demonstrates the quantification of bacterial load in a mouse model of chronic infection with streptomycin-resistant Salmonella typhimurium. Following euthanasia and sterile dissection, cecal and splenic tissues are harvested, homogenized with steel beads to release bacteria, and serially diluted. Dilutions are plated on selective agar, and visible colonies are counted to estimate...
03:33
Quantification of Bacterial Infection in Host Cells by the Colony-Forming Unit Assay
0 Views •
2025
This video demonstrates an in vitro quantification technique to determine Listeria monocytogenes infection of macrophages by the colony-forming unit assay. The bacterial colonies on the agar plate represent the intracellular bacterial population that escapes the host-defense mechanism and survives within the macrophages.
14:05
Imaging InlC Secretion to Investigate Cellular Infection by the Bacterial Pathogen Listeria monocytogenes
0 Views •
Cited by 7 •
2013
Listeria monocytogenes is a Gram positive bacterial pathogen frequently used as a major model for the study of intracellular parasitism. Imaging late L. monocytogenes infection stages within the context of small-interfering RNA screens allows for the global study of cellular pathways required for bacterial infection of target host cells.
10:23
Using Luciferase to Image Bacterial Infections in Mice
0 Views •
Cited by 22 •
2011
Methods for bioluminescence imaging of bacterial infections in living animals are decribed. Pathogens are modified to express luciferase allowing optical whole body imaging of infections in live animals. Animal models can be infected with luciferase expressing pathogens and the resulting course of disease visualized in real-time by bioluminescence imaging.
FAQs
Serial dilution and plating translates a sample into colony-forming units (CFUs), with each counted colony serving as the basis for estimating viable bacterial burden. Because the result reflects organisms able to produce colonies under the culture conditions used, it does not necessarily represent every bacterial cell or fragment present. This makes CFUs especially useful when viability is central to interpretation.
Quantitative PCR provides a different measurement by estimating bacterial DNA rather than counting colonies. This approach can reveal bacterial material when organisms are difficult to grow, extending detection beyond culture-dependent recovery. However, DNA-based values should not automatically be interpreted as viable-cell counts. Comparing qPCR with CFU data can clarify whether a change concerns total bacterial material, recoverable bacteria, or both.
A culture-based workflow typically uses serial dilution of the biological sample followed by plating and colony counting. The dilution step brings bacterial numbers into a countable range, while the resulting colony count supports calculation of the original burden. Consistent sample handling and clear identification of the dilution used are important because the numerical estimate depends on this sequence.
When evaluating antimicrobial treatment, the chosen measurement determines what a decrease means. A lower CFU value indicates fewer bacteria recoverable by culture, whereas a change in qPCR signal reflects bacterial DNA. Using both readouts can prevent an apparent treatment response from being overinterpreted and helps distinguish reduced viable burden from reduced or altered total bacterial material.
In immunology and infection studies, bacterial burden measurements can be paired with host immune-response data. This pairing allows investigators to ask whether differences in pathogen load accompany differences in the immune response, rather than examining either variable alone. The same measurements also support comparisons among infection models, giving a numerical basis for relating model-specific bacterial burden to host outcomes.
Researchers apply these measurements to assess infection severity and progression over the course of an experiment. Comparing burden estimates across conditions or time points provides a numerical basis for evaluating change, while treatment studies use them to assess antimicrobial activity. Interpretation remains dependent on the assay: culture emphasizes recoverable bacteria, whereas qPCR broadens assessment to bacterial DNA.