Related Experiment Video
Updated: May 16, 2026
08:06
The Use of a β-lactamase-based Conductimetric Biosensor Assay to Detect Biomolecular Interactions
Published on: February 1, 2018
Outer membrane vesicles shield Moraxella catarrhalis β-lactamase from neutralization by serum IgG
Viveka Schaar1, Magnus Paulsson, Matthias Mörgelin
1Medical Microbiology, Department of Laboratory Medicine Malmö, Lund University, Skåne University Hospital, Malmö, Sweden.
The Journal of Antimicrobial Chemotherapy
|November 28, 2012
Summary
Antibiotic resistance may spread as Moraxella catarrhalis beta-lactamase is found in outer membrane vesicles (OMVs). These OMVs protect the enzyme from antibodies, indicating a role in resistance dissemination.
Area of Science:
- Microbiology
- Immunology
- Bacterial pathogenesis
Background:
- Moraxella catarrhalis is a significant human pathogen.
- Beta-lactamase enzymes contribute to antibiotic resistance.
- Outer membrane vesicles (OMVs) are implicated in bacterial virulence and spread.
Purpose of the Study:
- To detect IgG against Moraxella catarrhalis beta-lactamase in healthy adults.
- To investigate if OMVs protect beta-lactamase from antibody inhibition.
Main Methods:
- Transmission electron microscopy to visualize beta-lactamase in OMVs.
- ELISA to detect specific IgG against M. catarrhalis beta-lactamase and adhesins.
- Flow cytometry to analyze IgG binding to OMVs.
- Nitrocefin assay to quantify beta-lactamase activity.
Main Results:
- Beta-lactamase was detected in OMVs from a sinusitis patient.
- Anti-beta-lactamase IgG was found in 15% of healthy adults.
- IgG from serum bound to beta-lactamase-positive OMVs.
- OMVs shielded active beta-lactamase from IgG inhibition.
Conclusions:
- Moraxella catarrhalis beta-lactamase is associated with OMVs, suggesting a role in antibiotic resistance spread.
- OMVs protect beta-lactamase from specific IgG, highlighting their clinical relevance.
Related Concept Videos
01:23Inhibitors of Gram-positive Cell Wall Synthesis
Bacterial cell walls are typically rigid structures composed mainly of peptidoglycan, a mesh-like polymer that provides mechanical strength and maintains cell shape. The synthesis of peptidoglycan is a crucial process in bacterial growth and serves as a primary target for many antibiotics.Mechanism of Action of Beta-Lactam AntibioticsBeta-lactam antibiotics, such as penicillin, inhibit peptidoglycan synthesis in actively growing cells. These antibiotics share a characteristic four-membered...
01:25Clinical 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...
01:31Defense Against Bacterial Pathogens
The human immune system is a complex network of cells, tissues, and organs that work together to defend the body against bacterial infections. It consists of various immune cells, each playing a specific role in the defense mechanism.
Phagocytes
Phagocytes are the frontline soldiers of the immune system. They include neutrophils and macrophages. Neutrophils are the most abundant type of white blood cell and are quickly mobilized to the site of infection. Macrophages are larger cells that patrol...
Phagocytes
Phagocytes are the frontline soldiers of the immune system. They include neutrophils and macrophages. Neutrophils are the most abundant type of white blood cell and are quickly mobilized to the site of infection. Macrophages are larger cells that patrol...
01:18Surface Membrane Barriers
The skin and mucous membranes serve as the primary line of defense against pathogens by providing both physical and chemical protection. These barriers are essential in preventing the entry and establishment of microbes, thereby maintaining the integrity of the host.
The outer layer of the skin, the epidermis, is a robust barrier comprising layers of closely packed keratinized cells. This dense arrangement prevents microbes from penetrating the body. The periodic shedding of epidermal cells...
The outer layer of the skin, the epidermis, is a robust barrier comprising layers of closely packed keratinized cells. This dense arrangement prevents microbes from penetrating the body. The periodic shedding of epidermal cells...
01:25Mechanism 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...
01:23Antimicrobial Proteins
Antimicrobial proteins are important components of the immune system. They aid the body in combating pathogens by either killing them directly or hindering their replication processes. Four main types of antimicrobial substances are interferons, the complement system, iron-binding proteins, and antimicrobial proteins.
Interferons
Interferons (IFNs) are proteins produced by lymphocytes, macrophages, and fibroblasts infected with viruses. While IFNs cannot prevent viruses from entering and...
Interferons
Interferons (IFNs) are proteins produced by lymphocytes, macrophages, and fibroblasts infected with viruses. While IFNs cannot prevent viruses from entering and...