Related Experiment Video
Updated: Aug 18, 2026

Testing the Role of Multicopy Plasmids in the Evolution of Antibiotic Resistance
Published on: May 2, 2018
Loss of plasmid DNA coding for beta-lactamase during experimental infection with Haemophilus influenzae type b
Abstract:
Apparent R factor-negative segregation was documented during infection of infant monkeys with two of three strains of ampicillin-resistant Haemophilus influenzae type b. In vitro the bacterial population of one strain (A-Sm) uniformly produced beta-lactamase. All bacteria isolated from blood or cerebrospinal fluid from both animals inoculated with strain A-Sm produced the enzyme. In contrast, 98% and 96% of bacteria from two other strains produced beta-lactamase in vitro. After intranasal inoculation of infant Macacca mulatta with these two strains, bacteria isolated from blood and cerebrospinal fluid uniformly did not produce beta-lactamase. Loss of the beta-lactamase-producing phenotype was associated with loss of plasmid DNA. Strains containing a mixed population of bacteria may undergo spontaneous loss of plasmid DNA during experimental infection. It is suggested that in these strains the bacteria carrying plasmids are less virulent.
More Related Videos
12:32Quantification of Plasmid-Mediated Antibiotic Resistance in an Experimental Evolution Approach
Published on: December 14, 2019
05:06Characterizing Multidrug Efflux Systems in Acinetobacter baumannii Using an Efflux-Deficient Bacterial Strain and a Single-Copy Gene Expression System
Published on: January 5, 2024
Related Concept Videos
Genomic DNA in Prokaryotes
Genomic Diversity in Bacteria
Although bacterial genomes are much...
Bacterial Transformation
Plasmids
Transduction
DNA Bacteriophages
Regulation of Bacterial Virulence