Related Experiment Video

Updated: Sep 8, 2026

Multiplex PCR Assay for Typing of Staphylococcal Cassette Chromosome Mec Types I to V in Methicillin-resistant Staphylococcus aureus
09:03

Multiplex PCR Assay for Typing of Staphylococcal Cassette Chromosome Mec Types I to V in Methicillin-resistant Staphylococcus aureus

Published on: September 5, 2013

The occurrence of two M antigens in certain group A streptococci related to type 14

G G WILEY, A T WILSON

    The Journal of Experimental Medicine
    |February 1, 1961
    PubMed

    Insights

    Group A Streptococcus strains previously classified as Type 14 were found to possess two distinct M antigens: Type 14 and Type 51. This discovery reclassifies some strains and highlights the complexity of M antigen identification in Streptococcus.

    Area of Science:

    • Microbiology
    • Immunology
    • Bacteriology

    Background:

    • Group A Streptococcus (GAS) is a significant human pathogen.
    • M proteins are critical virulence factors and serotyping targets in GAS.
    • Previous classification of GAS strains may not fully capture antigen diversity.

    Purpose of the Study:

    • To investigate the immunological properties of a GAS strain previously identified as Type 14.
    • To determine the presence and distinctness of M antigens within this strain and related isolates.
    • To refine the serotyping and classification of Group A Streptococcus strains.

    Main Methods:

    • Immunological characterization of M antigens from Group A Streptococcus strains.
    • Serological assays to differentiate between Type 14 and Type 51 M antigens.
    • Analysis of M antigen expression in parent strains and variants.

    Main Results:

    • A GAS strain previously classified as Type 14 was found to express two distinct M antigens: Type 14 and Type 51.
    • Most strains with the Type 14 M antigen also possessed the Type 51 M antigen, leading to a new designation: Type 14-51.
    • Some strains exhibited only one of the two M antigens, indicating variations in antigen expression.

    Conclusions:

    • The immunological classification of Group A Streptococcus requires careful consideration of multiple M antigens.
    • Some GAS strains previously considered M-negative may express a second, distinct M antigen.
    • Accurate M antigen identification is crucial for understanding GAS epidemiology and pathogenesis.
    Keywords:
    ANTIGENSSTREPTOCOCCUS/immunology

    Related Concept Videos

    Streptococcal Pharyngitis01:27

    Streptococcal Pharyngitis

    Streptococcal pharyngitis, commonly known as “strep throat,” is an acute infection of the oropharyngeal tissues caused by the Gram‑positive Group A Streptococcus (Streptococcus pyogenes). Transmission occurs primarily through respiratory droplets expelled during coughing, sneezing, or talking.Mechanisms of Host Entry and Immune EvasionUpon entering the host, S. pyogenes adheres to the mucosal epithelial cells of the pharynx via surface proteins, notably lipoteichoic acid and the antiphagocytic...
    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...
    Cross-reactivity00:42

    Cross-reactivity

    Overview
    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...
    Staphylococcal Skin Infections01:29

    Staphylococcal Skin Infections

    Staphylococcus aureus is a Gram-positive coccus that resides harmlessly on the skin and mucous membranes of healthy individuals. When the skin barrier is breached, it can shift from a commensal to an opportunistic pathogen. This transition is facilitated by surface adhesins, such as clumping factor B and S. aureus surface protein G (SasG), which bind to structural proteins, including loricrin and cytokeratin, in the damaged epidermis. Protein A, another key factor, binds the Fc region of...
    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...