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Native Bacterial Antigens - IVD Raw Material


Infectious diseases continue to be a major threat to human health. Factors that contribute to this include the changes in life style such as the increasing migration, the rising resistance of pathogens to antibiotherapy and the increasing number of immunosuppressed patients. While only about 5% of bacterial species are pathogenic, bacteria have historically been the cause of a disproportionate amount of human disease and death. Diseases such as tuberculosis, typhus, plague, diphtheria, typhoid, cholera, dysentery and pneumonia have taken a large toll of humanity. The diseases caused by these species of bacteria range from the relatively mild up to the rapidly fatal. Bacterial diseases are also major problems for livestock health, and the spread of bacteria from animals to humans remains a major public health problem worldwide. At the beginning of the twentieth century, pneumonia, tuberculosis and diarrhea were the three leading causes of death. Water purification, immunization (vaccination) and antibiotic treatment have reduced the morbidity and the mortality of bacterial disease. Vaccines and antimicrobial drugs have been developed and used for decades. Some bacterial diseases are controlled very successfully by their use, but others are not, and finding effective and safe vaccines to prevent them has been particularly difficult.

Bacterial infections

The group of bacterial pathogens with a dual intracellular/extracellular life style in the host is widespread and expanding Fig. 1 The group of bacterial pathogens with a dual
intracellular/extracellular life style in the host
is widespread and expanding (MT Silva, 2012)

The internal tissues are normally sterile. In some circumstances, however, some opportunistic pathogens are able to enter the host by taking advantage of injuries or breaches in one of the different host barriers. Bacterial pathogens have evolved a wide range of strategies to colonize and invade human organs, despite the presence of multiple host defense mechanisms. Extracellular pathogens use virulence mechanisms to evade the antimicrobial capabilities of humoral immunity and phagocytosis thus promoting extracellular multiplication. Staphylococcus aureus, Streptococcus pyogenes, Pseudomonas aeruginosa, Escherichia coli are typical examples of extracellular pathogens, and wound infections, osteomyelitis, scarlet fever, certain forms of pneumonia, urinary tract infections are examples of infections caused by these pathogens. Typically, these pathogens multiply in the host at extracellular sites such as mucosal surfaces, vascular, lymphatic, and body cavity fluids, and in interstitial spaces. Intracellular pathogens promote the entry into host cells including macrophages and non-professional phagocytes such as epithelial cells. Intracellular pathogenic bacteria have the ability to establish a relationship in the susceptible host which includes a stage of intracellular multiplication. Classical examples of intracellular pathogens are Brucella abortus, Listeria monocytogenes, Chlamydia trachomatis, Coxiella burnetii, Mycobacterium tuberculosis, Salmonella enterica, and typical infectious diseases caused by them include brucellosis, listeriosis, tuberculosis, and salmonellosis.

Virulence Factors

  • Adherence Factors: Fimbriae (pili) helps the bacteria to attach itself to the site of infection. The surface receptors on the epithelial cells and the adhesive structures (adhesins) on the bacterial surface are involved in this specific adhesion reaction. In addition to pili, a wide range of bacterial surface factors with adhesive properties have been described. These adhesins recognize various classes of host molecules including transmembrane proteins or components of the extracellular matrix.
  • Invasion Factors: When bacteria is able to invade the host tissues, it can cause a generalized or localized infection. Surface components that allow the bacterium to invade host cells can be encoded on plasmids, but more often are on the chromosome.
  • Toxigenicity: Bacteria are able to produce toxins that lead to an infection. These include exotoxins and endotoxins. Endotoxins are lipopolysaccharide on gram-negative bacteria that can cause fever, changes in blood pressure, inflammation, lethal shock, and many other toxic events. Exotoxins include several types of protein toxins and enzymes produced and/or secreted from pathogenic bacteria. Major categories include cytotoxins, neurotoxins, and enterotoxins.
  • Other factors: Some bacteria contain bacteriophages that give the organism its virulence. There are bacteria that contain plasmids and they are responsible for the presence of surface antigens. These plasmids give the bacteria multiple drug resistance and hence the infection becomes difficult to treat. Many bacteria are surrounded by capsules that protect them from opsonization and phagocytosis. There are bacteria that carry their antigens on the capsules to carry out lytic activity within the body cells.

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Detection of bacterial pathogens includes conventional culture-based, nucleic acid-based, biosensor-based and immunological-based methods. The detection of bacterial pathogens by immunological-based methods is based on antibody-antigen interactions. Creative Diagnostics offer a broad range of native bacterial antigens for diagnostic laboratories and research institutes, and is an ideal basis for the development and production of infectious disease kits and reagents. Welcome to contact us if you’d like to know more or have questions about our products.


  1. Johnny W. Peterson. Medical Microbiology. 4th edition. Chapter 7 Bacterial Pathogenesis. 1996.
  2. Manuel T. Silva. Classical labeling of bacterial pathogens according to their lifestyle in the host: inconsistencies and alternatives. Frontiers in Microbiology. 2012.
  3. David R, Pascale C. How bacterial pathogens colonize their hosts and invade deeper tissues. Microbes and Infection. 2015. 17(3): 173-183.
  4. Law WF , Mutalib N A , Chan K G , et al. Rapid methods for the detection of foodborne bacterial pathogens: principles, applications, advantages and limitations. Frontiers in Microbiology, 2015, 5:770.
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