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Agranulocytes
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LymphocytesMonocytes
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Diseases
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• Pneumococcal pneumonia-bacteria multiply in the alveoli causing damage to the alveolar lining and an inflammatory response• Sinusitis and otitis media-bacteria invade the sinuses or middle ear, often following a viral infection• Bacteremia and endocarditis-bacteria in the bloodstream or in the lining of the heart• Pneumococcal meningitis-bacteria that have spread to the meninges
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Plasma vs Serum
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Enzymes
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• Lipases– Digest lipids, allowing staphylococci to grow on the skin’s surface and in cutaneous oil glands• -lactamase– Breaks down penicillin– Allows the bacteria to survive treatment with -lactam antimicrobial drugs
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Normal Tuberculosis
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FluorescentAcid-Fast Stainof Sputum(AFB per field)0 to >9 = 4+
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Antibodies
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• Also called immunoglobulins (Ig)• Soluble, glycoprotein molecules that bind antigen• Secreted by plasma cells, which are activated and differentiated B cells • Considered part of the humoral immune response since bodily fluids such as lymph and blood were once called humors
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• Prevention
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– Proper food preparation and storage practices– Hand antisepsis is the most important measure in preventing nosocomial infections– Also important is the proper cleansing of wounds and surgical openings, aseptic use of catheters or indwelling needles, an appropriate use of antiseptics
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Enterrococcus
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• Important cause of nosocomial infections• Treatment is difficult because enterococci are often resistant to antimicrobials• Prevention is difficult, especially in a health care setting, where patients’ often have weakened immune systems
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Human Leukocytes
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Granulocytes:Neutrophils: 50-70% of circulating WBCMulti-lobed nucleus (>3 masses)>1010 neutrophils made every dayMajor phagocytes; Cells of acute inflammationEosinophils: 1-3% of circulating WBCBilobed nucleus; Parasite defense; Red granulesBasophils: 0.5-1% of circulating WBCBilobed nucleus; Contain histamine; Blue granules
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Antibody Function
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• Antigen-binding sites are complementary to antigenic determinants (epitopes)– Due to the close fit, can form strong, noncovalent interactions– Hydrogen bonds, ionic attractions, and hydrophobic interactions are involved
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Vaccine Safety 2
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– Residual virulence• Attenuated viruses occasionally cause disease in healthy children or adults– Allegations that certain vaccines against childhood diseases cause or trigger autism, diabetes, and asthma• Research has not substantiated these allegations
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Streptococcus pneumoniae
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• Gram-positive cocci that most commonly forms pairs but may also form chains• Forms unpigmented, alpha-hemolytic colonies when grown on blood agar (anaerobic incubation produces beta-hemolytic colonies)• Normally colonizes the mouth and pharynx but can cause disease if they travel to the lungs• Disease is highest in children and the elderly
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Erysipelothrix rhusiopathiae
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• Gram-positive rod commonly found in farm animals (especially tonsils of pigs).• Causes epidemics of swine erysipelas.• Humans at risk are those who handle animals.• Portal of entry is usually a scratch on the hand or arm; org multiplies and causes erysipeloid.• Erysipeloid is characterized by dark red lesions that burn and itch.• Treated with penicillin or erythromycin.• Prevented by wearing gloves.
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Mycobacterium
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• 3 main mycobacterial diseases in humans:– Tuberculosis– Leprosy– Buruli ulcer• Estimated 1/3 of world population is infected with TB. It is the number 3 cause of death from infectious disease; number 1 from a single organism. 15 million cases in U.S.
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Blood
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Operates when pathogens succeed in penetrating the skin or mucous membranesNonspecific defenseComposed of cells, antimicrobial chemicals, and processes but no physical barriersMany of these components are contained or originate in the blood
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Phagocytosis
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Cells capable of phagocytosis (certain leukocytes or their derivatives) are called phagocytesPhagocytosis is performed chiefly by neutrophils (microphages) and macrophages.Can be divided into 5 stages
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Passive
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passively receive antibodies made by another individual
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Antibody Functions:
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• Neutralization (both viruses and toxins)• Opsonization• Agglutination• Activation of complement
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EffectorT CellsCytokines
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• Soluble regulatory proteins that act as intercellular signals when released from certain body cells• Immune system cytokines signal among various leukocytes• The complex web of signals among all the cell types of the immune system is referred to as the cytokine network
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Passive immunization
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individual acquires immunity through the transfer of antibodies formed by an immune individual or animal
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Bacillus, Clostridium, and Listeria
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• Genera of bacilli-shaped organisms
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Diagnosis, Treatment, and Prevention of S. agalactie
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• Prevention – Prophylactic administration of penicillin at birth to children whose mothers’ urinary tracts are colonized with group B streptococci– Immunization of women against group B streptococci to prevent infection of future children
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Formed Elements
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Erythrocytes- carry oxygen and carbon dioxide in the blood (4.2-6.2x109/ml)Platelets- involved in blood clotting and inflammation (1.3-4x108/ml)Leukocytes- involved in defending the body against invaders (4.5-11x106/ml)2 groups:GranulocytesAgranulocytes
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Number of Alleles in Caucasoids:Antigen Processing
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• T-independent antigen– Large antigen molecules with readily accessible, repeating antigenic determinants– B cells can bind and respond to these directly without T cell cytokine help• Stimulates B cells to differentiate into a plasma cell and produce antibodies
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Neutralization Tests
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• Based on the concept that antibodies can neutralize biological activity of many pathogens and their toxins• 2 Neutralization tests:– Viral neutralization– Viral hemagglutination inhibition test
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Pathogenicity and Diseases of S. agalactaie
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• Pathogenicity– Often infects newborns who have not yet formed type-specific antibodies and whose mothers are uninfected (and so do not provide passive immunity)– Produces various enzymes whose roles in causing disease is not yet understood• Diseases– Most often associated with neonatal bacteremia, meningitis, and pneumonia– Immunocompromised older patients are at risk from group B streptococcal infections
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Drugs Used to Treat Tuberculosis:
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• Directly observed therapy (DOT)• Rifater =INH + rifampin + pyrazinamide.• Vaccine = Bacille Calmet-Guerin (BCG) strain of M. bovis. BCG about 80% effective in kids,only 20-50% effective in adults.
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Chronic inflammation
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• Develops slowly and lasts a long time– Can cause damage to tissues
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Other First-Line Defenses
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Many body organs secrete chemicals with antimicrobial propertiesLacrimal glands that bathe the eyeSalivaStomach acid
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Memory B Cells
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• Cells produced by B cell proliferation that do not secrete antibodies• Cells that have BCRs complementary to the specific antigenic determinant that triggered their production• Long-lived cells that divide only a few times and then persist in the lymphoid tissue• Are available to initiate antibody production more rapidly if the same antigen is encountered again
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Active immunization
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administration of a vaccine so that the patient actively mounts a protective immune response
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Labeled Antibody Test
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• Use antibody molecules that are linked to some molecular “label” that enables them to be easily detected• Used to detect either antigens or antibodies• 3 examples – Fluorescent antibody tests– ELISA– Western blot test
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Structural Defenses Against Phagocytosis
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• Protein A coats the cell surface– Interferes with humoral immune responses by binding to IgG antibodies by Fc end– Inhibits the complement cascade• Bound coagulase– Converts the soluble blood protein fibrinogen into insoluble fibrin molecules that form blood clots– Fibrin clots hide the bacteria from phagocytic cells
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Swimming pool granuloma caused by Mycobacterium marinumLeprosy
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• Caused by Mycobacterium leprae• Bacteria have never been grown in cell-free culture• Cases of leprosy are becoming relatively rare• Transmission is via person-to-person contact or through a break in the skin
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Host Cell Protection
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The host’s cells are protected from destruction by the phagocytesSome phagocytes have receptors for bacterial surface components, such as flagellar proteins or cell wall components, that are lacking on the body’s cellsOpsonins such as certain complement split products and antibody provide a handle for the phagocyte
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Cytotoxic T cells (TC Cells)
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• Distinguished by the CD8 cell-surface glycoprotein• Directly kill certain cells– Cells infected with viruses and other intracellular pathogens– Abnormal cells, such as cancer cells
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Adult Immunization ScheduleModern Vaccine Technology
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• Research attempts to make vaccines that are more effective, cheaper, and safer• A variety of recombinant DNA techniques can be used to make improved vaccines
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Problems with Inactivated Vaccines
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• Do not stimulate herd immunity • Whole agent vaccines may stimulate an inflammatory response due to nonantigenic portions of the microbe• Weak immunogenicity, since the microbes don’t reproduce and are cleared before they stimulate a strong immune response
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• Food Poisoning
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– S. aureus is the number 1 cause in the U. S.– Enterotoxin-producing strains contaminate food from the processor. If the food is not refrigerated, the organisms grow and produce the toxin that is ingested. Disease results.– Symptoms include extreme nausea and vomiting, 2-4 hours after eating. Diarrhea may be present.
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Skin – Chemical Components of Defense
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Perspiration secreted by sweat glandsSebum secreted by sebaceous (oil) glands
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History of Immunization
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• Since the Latin word for cow is vacca, this process was called vaccination, and the inoculum was termed a vaccine• Louis Pasteur developed a vaccine against Pasteurella multocida• Practice of transferring protective antibodies was developed when it was discovered that vaccines protected through the action of antibodies
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CAMP Test for Group B StrepEnterrococcus
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• Previously classified as group D streptococci but differed enough to be reclassified as a separate genus• Form short chains and pairs and lack a capsule• Found in the human colon but are rarely pathogenic at this site• Can cause disease if they are introduced into other parts of the body, such as the urinary tract or bloodstream
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Lymphocyte Editing by Clonal Deletion
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• Vital that immune responses not be directed against self (autoantigens)• Body “edits” lymphocytes to eliminate any self-reactive cells
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Sebum secreted by sebaceous (oil) glands
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Helps keep skin pliable and less likely to break or tearLowers the pH of the skin to a level inhibitory to many bacteria
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