Related Experiment Video

Updated: Sep 2, 2026

Forward Genetic Approaches in Chlamydia trachomatis
09:03

Forward Genetic Approaches in Chlamydia trachomatis

Published on: October 23, 2013

CHANGES IN MOUSE PNEUMONITIS AGENT ASSOCIATED WITH DEVELOPMENT OF RESISTANCE TO CHLORTETRACYCLINE

J W MOULDER, D L NOVOSEL, I I TRIBBY

    Journal of Bacteriology
    |January 1, 1965
    PubMed

    Insights

    A chlortetracycline-resistant mutant of mouse pneumonitis agent exhibited altered characteristics, including resistance to other drugs and increased virulence. These changes suggest a genetically controlled modification in the microorganism

    Area of Science:

    • Microbiology
    • Bacteriology
    • Virology

    Background:

    • Mouse pneumonitis agent belongs to the psittacosis group of microorganisms.
    • Antibiotic resistance is a significant challenge in microbial infections.

    Purpose of the Study:

    • To investigate the changes in mouse pneumonitis agent associated with the development of chlortetracycline resistance.
    • To characterize the properties of a chlortetracycline-resistant mutant.

    Main Methods:

    • Serial passage of mouse pneumonitis agent in chick embryos with chlortetracycline.
    • Characterization of the resistant mutant's properties, including antibiotic resistance, growth cycle, particle size, antigenicity, and virulence.

    Main Results:

    • The chlortetracycline-resistant mutant showed complete resistance to chlortetracycline and increased resistance to d-cycloserine.
    • The mutant had a longer growth cycle and produced more large particles.
    • The resistant mutant was not neutralized by parent antiserum and vice versa, indicating antigenic changes.
    • The resistant mutant exhibited high lethality in mice upon intracerebral inoculation.

    Conclusions:

    • The observed changes in the resistant mutant are likely due to a genetically controlled alteration in the surface structure of the mouse pneumonitis particle.
    • This surface modification enables the multiplication of the mutant in the presence of chlortetracycline.
    Keywords:
    ALANINEANTIGEN-ANTIBODY REACTIONSBENZOPYRENESCHICK EMBRYOCHLORTETRACYCLINECYCLOSERINEDRUG RESISTANCE, MICROBIALEXPERIMENTAL LAB STUDYMICEMIYAGAWANELLAMUTATIONPENICILLIN GPHARMACOLOGYSULFADIAZINE

    Related Concept Videos

    Mechanism of Antibiotic Resistance in MRSA01:25

    Mechanism of Antibiotic Resistance in MRSA

    Antibiotic resistance in bacteria arises when microorganisms evolve the ability to withstand drugs designed to kill them or inhibit their growth, rendering once-effective treatments useless. This phenomenon, driven by genetic change and selection under antibiotic exposure, poses a profound threat to modern medicine. Mechanisms include drug-inactivating enzymes (e.g., β-lactamases), efflux pumps that eject antibiotics, mutations altering antibiotic targets, decreased drug uptake, and acquisition...
    Development of Antibiotic Resistance01:30

    Development of Antibiotic Resistance

    Antibiotic resistance is a major public health concern that arises when bacteria evolve mechanisms to withstand the effects of antibiotic treatments. This resistance can be intrinsic, acquired through genetic mutations, or transferred between bacteria via horizontal gene transfer. The development of antibiotic resistance poses significant challenges in treating bacterial infections and necessitates ongoing research to develop new therapeutic strategies.Intrinsic resistance occurs when bacterial...
    Atypical Pneumonia01:14

    Atypical Pneumonia

    Atypical pneumonia, often caused by Mycoplasma pneumoniae, is a form of pulmonary infection that differs from the classical presentation of bacterial pneumonia in both its cause and clinical symptoms. Mycoplasma pneumoniae is a pleomorphic bacterium notable for its lack of a rigid cell wall. This structural characteristic imparts resistance to beta-lactam antibiotics and significantly influences the bacterium’s behavior within the human host.Other pathogens responsible for the disease include...
    Clinical Significance of Antibiotic Resistance01:25

    Clinical Significance of Antibiotic Resistance

    Methicillin-resistant Staphylococcus aureus (MRSA) presents a critical public health threat, arising from its capacity to resist β-lactam antibiotics due to acquisition of the mecA gene within the staphylococcal cassette chromosome mec (SCCmec). This gene encodes penicillin-binding protein 2a (PBP2a), which impairs binding efficacy of methicillin and other β-lactams. MRSA has evolved into distinct clonal lineages impacting humans and animals alike, reinforcing its significance within the One...
    Bacterial Phylum Chlamydiae01:29

    Bacterial Phylum Chlamydiae

    The phylum Chlamydiae or Chlamydiota is composed of a single order, Chlamydiales. This phylum consists entirely of obligate intracellular parasites that infect eukaryotic hosts. While human pathogens within this group have been studied extensively, the phylum encompasses many species capable of interacting with various eukaryotic organisms. Members of Chlamydiae are typically small cocci, approximately 0.5 μm in diameter, and exhibit a distinctive developmental cycle. As is characteristic of...
    Antibiotic Selection01:45

    Antibiotic Selection

    Researchers use antibiotic resistance genes to identify bacteria that possess a plasmid containing their gene of interest. Antibiotic resistance naturally occurs when a spontaneous DNA mutation creates changes in bacterial genes that eliminate antibiotic activity. Bacteria can share these new resistance genes with their offspring and other bacteria. The overuse and misuse of antibiotics have created a public health crisis, as resistant and multi-resistant bacteria continue to develop.Antibiotic...