Infectious Diseases (Microbiology) PDF

INFECTIOUS DISEASES The material is intended for educational purpose only. The images and videos used in this presentation do not belong to the lecturer and are obtained from various sources to facilitate discussion 10/11/2024 MNRubio,M.D....

INFECTIOUS DISEASES The material is intended for educational purpose only. The images and videos used in this presentation do not belong to the lecturer and are obtained from various sources to facilitate discussion 10/11/2024 MNRubio,M.D. 1 General Principles of Microbial Pathogenesis infectious diseases remain an important health problem throughout the world, despite the availability of effective vaccines and antibiotics – important causes of death among older adults and in people: immunosuppressed suffer from debilitating chronic diseases – Why? inadequate access to medical care Malnutrition – six of the ten leading causes of death are infectious diseases Who are affected? – most deaths > children with respiratory and diarrheal infections taking the greatest toll 10/11/2024 MNRubio,M.D. 2  How Microorganisms Cause Disease Routes of entry: – A. breaching epithelial surfaces – B. inhalation – C. ingestion – D. sexual transmission Healthy individuals – Entry thru the RT, GIT, GUT – by virulent microorganisms – Skin (injured) – by less virulent microorg 10/11/2024 MNRubio,M.D. 3 General Principles of Microbial Pathogenesis Skin: Protection via : – A. intact keratinized epidermis – strong mechanical barrier – B. antimicrobial fatty acids – C. defensins – small peptides toxic to bacteria Intact skin traversed by: – Larvae of Schistosoma – release enzymes that dissolve the adhesive proteins holding the keratinocytes together – Dermatophytes 10/11/2024 MNRubio,M.D. 4 General Principles of Microbial Pathogenesis GIT: – Thru contaminated food and drinks Local defenses: – 1. acidic gastric secretions - highly effective at killing certain organisms Infective dose of vibrio cholerae – 10 11 Organism reduced by neutralizing stomach acid to 10,000 fold – 2. Viscous layer of mucus throughout the gut length – 3. Pancreatic enzymes – 4. Bile detergents 10/11/2024 MNRubio,M.D. 5 General Principles of Microbial Pathogenesis 5. IgA abs – from lymphoid tissues (Peyer’s patches) 6. Peristalsis – clear organisms preventing overgrowth 7. Normal gut flora - creation of a microenvironment preventing the colonization of potential pathogen (Cl. deficile) 10/11/2024 MNRubio,M.D. 6  General Principles of Microbial Pathogenesis 10/11/2024 MNRubio,M.D. 7  General Principles of Microbial Pathogenesis Gastrointestinal tract infections ➔local defenses are circumvented by a pathogen, or when they are so weakened that even normal flora ➔ disease. Ex: – Norovirus - ⏎ non-enveloped virus – resistant to inactivation by acid, bile, and pancreatic enzymes – Cystic protozoans Acid-resistant coat – Eggs of Helminths – Shigella – Dose – 100 10/11/2024 orgs MNRubio,M.D. 8  Enteropathogenic pathogens may establish symptomatic gastrointestinal disease through several distinct mechanisms : 1. Adhesion and local proliferation. – Ex: V. cholerae, enterotoxigenic E. coli 2. Adhesion and mucosal invasion – Ex: Shigella, Salmonella enterica, Campylobacter jejuni, and Entamoeba histolytica 3. “Hijacking” of host pathways of antigen uptake. – Ex: Poliovirus 10/11/2024 MNRubio,M.D. 9  Respiratory Tract Inhalation : dust/ aerosols ❖The distance these particles travel into the respiratory system is inversely proportional to their size. ❖Large particles are trapped in the mucociliary blanket that lines the nose and the upper respiratory tract ➔ transported by ciliary action to the back of the throat➔ swallowed. ❖Particles < 5 microns ➔ alveoli, where they are phagocytosed by resident alveolar macrophages or by neutrophils recruited to the lung by cytokines. 10/11/2024 MNRubio,M.D. 10 Urogenital Tract – Protected from infection - regular emptying during micturition(urinate). Factors: 1. Anatomy – Females: 10x more UTI than males – Length of urethra – 5 cm female/ 10 cm male 2. Obstruction of urinary flow 3. Reflux of urine Both compromise normal defenses and increases susceptibility to urinary tract infections. 4. Antibiotics – killing lactobacillus 5. Trauma to cervical epithelium 10/11/2024 MNRubio,M.D. 11  Vertical Transmission – from mother to fetus or newborn child may occur through several different routes. 1. Placental-fetal transmission. – Ex: Rubella infection 2. Transmission during birth. – Ex: gonococcal and chlamydial conjunctivitis 3. Postnatal transmission in maternal milk. – Ex: cytomegalovirus (CMV), human immunodeficiency virus (HIV), and hepatitis B virus (HBV). 10/11/2024 MNRubio,M.D. 12  Spread and Dissemination of Microbes Within the Body Disease-causing organisms may – 1. Remain localized from the site of I0 site of infection – 2. Invade tissues – 3. Spread to distant sites via: – lymphatics, the blood, or the nerves Ex: S. aureus > localized > Hyaluronidase > degrades ECM > neighboring tissue cells ➔lymphatics ➔regional lymph nodes ➔ blood, (bacteremia) and spread ➔distant organs ( heart and bone). 10/11/2024 MNRubio,M.D. 13  Spread and Dissemination of Microbes Within the Body Exit from the body: – skin shedding – coughing – sneezing – voiding of urine or feces – during sexual contact – through insect vectors – Person to person thru respiratory, fecal-oral, sexual routes 10/11/2024 MNRubio,M.D. 14  Spread and Dissemination of Microbes Within the Body Disease-causing organisms may – Thru CNS : poliovirus, rabies, Varicella ➔ infecting peripheral nerves ➔ traveling intracellularly along axons ➔ CNS. The consequences of blood-borne spread of pathogens vary widely depending on: – virulence of the organism – magnitude of the infection – pattern of seeding – host factors: immune status 10/11/2024 MNRubio,M.D. 15  Host-Pathogen Interactions Factors affecting the outcome of infection: 1. virulence of the microbe 2. nature of the host immune response: – eliminate the infection – exacerbate – be the principal cause of tissue damage 10/11/2024 MNRubio,M.D. 16  Host-Pathogen Interactions Immune evasion 1. Antigenic variation. – “change their coats” by expressing different surface antigens (Spirochetes) – frequenct recombination events, permitting antigenic “drift” and “shifts”(Influenza) – Diff serotypes have diff capsular polysaccharides (S. pneumoniae) – fidelity of viral RNA polymerases (HIV, many respiratory viruses, influenza virus) create viral antigenic variation 10/11/2024 MNRubio,M.D. 17 10/11/2024 MNRubio,M.D. 18  Host-Pathogen Interactions Immune evasion 2. Resistance to antimicrobial peptides – to avoid killing by peptides include changes in net surface charge and membrane hydrophobicity that prevent antimicrobial peptide insertion and pore formation, secretion of proteins that inactivate or degrade the peptides, and pumps that export the peptides. 3. Resistance to killing by phagocytes. 4. Evasion of apoptosis and manipulation of host cell metabolism. 5. Resistance to cytokine-,chemokine-and complement-mediated host defense 10/11/2024 MNRubio,M.D. 19  Host-Pathogen Interactions Immune evasion 6. Evasion of recognition by CD4+ helper T cells and CD8+ cytotoxic T cells. 7. immunoregulatory mechanisms to downregulate anti-microbial T cell responses. 8. to “lie low” by establishing a state of latent infection in which few if any viral genes are expressed. 10/11/2024 MNRubio,M.D. 20  Host-Pathogen Interactions 10/11/2024 MNRubio,M.D. 21  Host-Pathogen Interactions Injurious Effects of Host Immunity 1. Inflammation (granulomatous – TB) > prevents their spread > tissue damage > fibrosis 2. Inflammation due to >Immune complexes – Ex: RHD, AGN 3. Chronic inflammation 10/11/2024 4. Cancer MNRubio,M.D. 22  Host-Pathogen Interactions Infections in People with Immunodeficiencies 1. Antibody deficiencies – Ex: X-linked agammaglobulinemia > susceptible to: by extracellular bacteria, including S. pneumoniae, H. influenzae, and S. aureus, as well as a few viruses (rotavirus and enteroviruses). 2. Complement defects – A. early components of the complement cascade lead to susceptibility to infections by encapsulated bacteria (S. pneumoniae) – B. deficiencies of the late membrane attack complex components (C5-C9) are associated with Neisseria infections 10/11/2024 MNRubio,M.D. 23  Host-Pathogen Interactions 3. Defects in neutrophil function lead to increased susceptibility to infections with S. aureus, some gram-negative bacteria, and fungi. 4. Defects in Toll-like receptor (TLR) signaling pathways – Mutations in MyD88 or IRAK4, which are downstream of several TLRs, predispose to pyogenic bacterial infections, particularly invasive infections with S. pneumoniae – Impaired TLR3 responses are associated with childhood herpes simplex virus encephalitis. 10/11/2024 MNRubio,M.D. 24  Host-Pathogen Interactions 5. T-cell defects lead to susceptibility to intracellular pathogens, particularly viruses and some parasites. – Inherited mutations that impair the generation of TH1 cells (such as mutations in IL-12 or IFN-γ receptors, or the transcription factor STAT1) are associated with atypical mycobacterial infections. – Defects that impair the generation of TH17 cells (such as mutations in STAT3) are associated with chronic mucocutaneous candidiasis 10/11/2024 MNRubio,M.D. 25  Host Damage Infectious agents establish infection and damage tissues by three mechanisms: 1. They can contact or enter host cells and cause cell death directly, or cause changes in cellular metabolism and proliferation that can eventually lead to transformation. 2. They may release toxins that kill cells at a distance, release enzymes that degrade tissue components, or damage blood vessels and cause ischemic necrosis. 3. They can induce host immune responses that, though directed against the invader, cause additional tissue damage. 10/11/2024 MNRubio,M.D. 26  Mechanisms of Viral Injury Enter the cells >>replication >> direct damage to the cell Tropism - predilection for viruses to infect certain cells and not others. A major determinant of tissue tropism: – A. Presence of viral receptors on host cells. – B. Physical barriers also can contribute to tissue tropism. 10/11/2024 MNRubio,M.D. 27  Mechanisms of Viral Injury A. Receptors Viruses: – With surface proteins that bind to particular proteins found on the surface of host cells normally function as receptors for host factors Ex: I. HIV glycoprotein gp120 bind to – 1. CD4 on T cells – 2. chemokine receptors CXCR4 (mainly on T cells) 3. CCR5 (mainly on macrophages) II. EBV binds to: – complement receptor 2 (aka CR2 or CD21) on B cells 10/11/2024 MNRubio,M.D. 28  Mechanisms of Viral Injury B. Physical barriers also can contribute to tissue tropism. Ex: E – Enteroviruses replicate in the intestine in part because they can resist inactivation by acids, bile, and digestive enzymes. – Rhinoviruses infect host cells only within the upper respiratory tract because they replicate optimally at the lower temperatures found in sites exposed to the ambient atmosphere. 10/11/2024 MNRubio,M.D. 29  Mechanisms of Viral Injury Once viruses are inside host cells, they can damage or kill the cells by a number of mechanisms: 1. Direct cytopathic effects. 2. Anti-viral immune responses. 3. Transformation of infected cells into benign or malignant tumor cells. 10/11/2024 MNRubio,M.D. 30  Mechanisms of Bacterial Injury 1. Bacterial Virulence – Bacterial damage to host tissues depends on the ability of the bacteria to adhere to host cells, invade cells and tissues, or deliver toxins 2. Bacterial Adherence to Host Cells – Adhesins - bacterial surface molecules that bind to host cells or extracellular matrix – Pili - filamentous proteins on the surface of bacteria 10/11/2024 MNRubio,M.D. 31  Mechanisms of Bacterial Injury MECHANISMS OF BACTERIAL INJURY 3. Mobile genetic elements can transmit functionally important genes to bacteria, including genes that influence pathogenicity and drug resistance. A. plasmids sometimes contains genes for toxins B. bacteriophages often contains genes for toxins (including the genes that encode the toxins responsible for the pathogenesis of cholera, diphtheria and botulism). 10/11/2024 MNRubio,M.D. 32  Mechanisms of Bacterial Injury 4. Virulence of Intracellular Bacteria – Opsonization of bacteria with antibodies or the complement protein C3b promotes phagocytosis of bacte- ria by macrophages. – Shigella and E. coli inhibit host protein synthesis, replicate rapidly, and lyse the host cell within 6 hours – M. tuberculosis blocks fusion of the lysosome with the phagosome, allowing it to proliferate unchecked within the macrophage – L. monocytogenes produces a pore-forming protein called listeriolysin O and two phospholipases that degrade the phagosome membrane, allowing the bacteria to escape into the cytoplasm 10/11/2024 MNRubio,M.D. 33  Mechanisms of Bacterial Injury 5. Bacterial Toxins – endotoxins, which are components of the bacterial cell – exotoxins, which are proteins that are secreted by the bacterium – Bacterial endotoxin lipopolysaccharide (LPS) that is a large component of the outer membrane of gram-negative bacteria – Exotoxins- bacterial proteins that cause cel- lular injury and disease. 10/11/2024 MNRubio,M.D. 34  Mechanisms of Bacterial Injury 5. Bacterial Toxins – Exotoxins- acterial proteins that cause cel- lular injury and disease. – Enzymes. proteases, hyaluronidases, coagulases, fibrinolysins) – Toxins that alter intracellular signaling or regulatory pathways. – Neurotoxins Clostridium botulinum and Clostridium tetani inhibit release of neurotransmitters, resulting in paralysis. – Superantigens bacterial toxins that stimulate very large number of T lymphocytes by binding to conserved portions of the T-cell receptor, leading to massive T-lymphocyte proliferation and cytokine release. 10/11/2024 MNRubio,M.D. 35  SEXUALLY TRANSMITTED DISEASES General features: 1. STIs may become established and spread from the urethra, vagina, cervix, rectum, or oral pharynx. 2. Infection with one STI-associated organism increases the risk for additional STIs. (N. gonorrhea, C. trachomatis) 3. The microbes that cause STIs can be spread from a pregnant woman to the fetus and cause severe damage to the fetus or child. (C. trachomatis, HSV, HIV) 10/11/2024 MNRubio,M.D. 36 SPECTRUM OF INFLAMMATORY RESPONSES TO INFECTION Suppurative (Purulent) Inflammation characterized by increased vascular permeability and leukocytic infiltration, predominantly of neutrophils Massing of neutrophils and liquefactive necrosis of the tissue form pus Suppurative (purulent) infection.Pneumococcal pneumonia with extensive neutrophilic infiltrate. 10/11/2024 MNRubio,M.D. 37  SPECTRUM OF INFLAMMATORY RESPONSES TO INFECTION Mononuclear and Granulomatous Inflammation Granulomatous inflammation - characterized by accumulation of activated macrophages called “epithelioid” cells, which may fuse to form giant cells. In some cases there is a central area of caseous necrosis Secondary syphilis in the dermis with perivascular lymphoplasmacytic infiltrate and endothelial 10/11/2024 proliferation. MNRubio,M.D. 38 SPECTRUM OF INFLAMMATORY RESPONSES TO INFECTION Cytopathic-Cytoproliferative Reaction usually produced by viruses characterized by cell necrosis or cellular proliferation, usually with sparse inflammatory cells Some viruses replicate within cells and make viral aggregates that are visible as inclusion bodies (herpesviruses or adenovirus) or induce cells to fuse and form multinucleated cells called polykaryons (measles virus or herpesviruses) Herpesvirus blister in mucosa. See Figure 8-9 for viral inclusions. 10/11/2024 MNRubio,M.D. 39 SPECTRUM OF INFLAMMATORY RESPONSES TO INFECTION Cytopathic-Cytoproliferative Reaction Focal cell damage in the skin may cause epithelial cells to become detached, forming blisters Some viruses can cause epithelial cells to proliferate (venereal warts caused by HPV or the umbilicated papules of molluscum contagiosum caused by poxviruses) viruses can contribute to Herpesvirus blister in mucosa. See Figure 8-9 for the development of viral inclusions. malignant neoplasms 10/11/2024 MNRubio,M.D. 40  SPECTRUM OF INFLAMMATORY RESPONSES TO INFECTION Tissue Necrosis Clostridium perfringens and other organisms that secrete powerful toxins can cause such rapid and severe necrosis (gangrenous necrosis) few inflammatory cells are present lesions resemble infarcts with disruption or loss of basophilic nuclear staining and preservation of cellular outlines 10/11/2024 MNRubio,M.D. 41  SPECTRUM OF INFLAMMATORY RESPONSES TO INFECTION Chronic Inflammation and Scarring Many infections elicit chronic inflammation, which can lead either to complete healing or to extensive scarring. chronic HBV infection may cause cirrhosis of the liver, in which dense fibrous septae surround nodules of regenerating hepatocytes 10/11/2024 MNRubio,M.D. 42  Special Techniques for Diagnosing Infectious Agents Gold standards for diagnosis of infections: culture biochemical or serologic identification molecular diagnosis, depending on the organism in question 10/11/2024 MNRubio,M.D. 43  Special Techniques for Diagnosing Infectious Agents 10/11/2024 MNRubio,M.D. 44  VIRAL INFECTION 10/11/2024 MNRubio,M.D. 45  Selected Human Viruses and Viral Diseases Organ System Species Disease Respiratory Adenovirus Upper and lower respiratory tract infections, conjunctivitis, diarrhea Rhinovirus Upper respiratory tract infection Influenza viruses A, B Influenza Respiratory syncytial virus Bronchiolitis, pneumonia Digestive Mumps virus Mumps, pancreatitis, orchitis Rotavirus Childhood gastroenteritis Norovirus Gastroenteritis Hepatitis A virus Acute viral hepatitis Hepatitis B virus Acute or chronic hepatitis Hepatitis D virus With HBV, acute or chronic hepatitis Hepatitis C virus Acute or chronic hepatitis Hepatitis E virus Enterically transmitted hepatitis 10/11/2024 MNRubio,M.D. 46  Organ System Species Disease Systemic with Skin Eruptions Measles virus Measles (rubeola) Rubella virus German measles (rubella) Varicella-zoster virus Chickenpox, shingles Herpes simplex virus 1 Oral herpes (“cold sore”) Herpes simplex virus 2 Genital herpes Systemic with Hematopoietic Cytomegalovirus Cytomegalic inclusion disease Disorders Epstein-Barr virus Infectious mononucleosis HIV-1 and HIV-2 AIDS Arboviral and Hemorrhagic Dengue virus 1–4 Dengue hemorrhagic fever Fevers Yellow fever virus Yellow fever Skin/Genital Warts Papillomavirus Condyloma; cervical carcinoma Central Nervous System Poliovirus Poliomyelitis JC virus Progressive multifocal leukoencephalopathy (opportunistic) 10/11/2024 MNRubio,M.D. 47  ACUTE (TRANSIENT) INFECTIONS 10/11/2024 MNRubio,M.D. 48  Acute (Transient) Infections MEASLES leading cause of vaccine-preventable death and illness worldwide. single-stranded RNA virus of the paramyxovirus family, which includes mumps, respiratory syncytial virus, parainfluenza virus (a cause of croup), and human metapneumovirus. MOT: respiratory droplets Three cell-surface receptors: – 1. CD46 (a complement-regulatory protein that inactivates C3 convertases) – 2. signaling lymphocytic activation molecule (SLAM, a molecule involved in T-cell activation) – 3. nectin 4 (adherens junction protein). 10/11/2024 MNRubio,M.D. 49  Acute (Transient) Infections MEASLES Antibody-mediated immunity to measles virus protects against reinfection. cause transient but profound immunosuppression, resulting in secondary bacterial and viral infections, which are responsible for much of measles-related morbidity and mortality. Pathognomonic sign: Koplik spots Multinucleate giant cells: wMeasles giant cells in the lung. Note the glassy Warthin-Finkeldey cells, eosinophilic intra- nuclear inclusions. 10/11/2024 MNRubio,M.D. 50  Acute (Transient) Infections MUMPS – associated with pain and swelling of the salivary glands. – mumps virus is a member of the paramyxovirus family has two types of surface glycoproteins – 1. one with hemagglutinin and neuraminidase activities – 2. with cell fusion and cytolytic activities. 10/11/2024 MNRubio,M.D. 51  Acute (Transient) Infections MUMPS Complications: – Aseptic meningitis is the most common extrasalivary gland complication of mumps causes perivenous demyelination and perivascular mononuclear cuffing – Mumps parotitis – 70% bilateral – Mumps orchitis - testicular damage can lead to scarring, atrophy, and, if severe, sterility – Pancreas - release digestive enyzmes, causing parenchymal and fat necrosis and neutrophil-rich inflammation. 10/11/2024 MNRubio,M.D. 52  Acute (Transient) Infections Poliovirus Infection – acute systemic viral infection, leading to a wide range of manifestations, from mild, self-limited infections to paralysis of limb muscles and respiratory muscles – spherical, unencapsulated RNA virus of the enterovirus genus. – There are three serotypes of poliovirus, each of which is included in the Salk formalin-fixed (killed) vaccine and the Sabin oral, attenuated (live) vaccine. 10/11/2024 MNRubio,M.D. 53  Acute (Transient) Infections Poliovirus Infection MOT: fecal-oral route virus infects human cells by binding to CD155, an epithelial adhesion molecule. Ingestion > replicates (mucosa of the pharynx and gut, including tonsils and Peyer patches in the ileum). > spreads through lymphatics > lymph nodes > blood, > transient viremia and fever > CNS > replication motor neurons of the spinal cord (spinal poliomyelitis) or brain stem (bulbar poliomyelitis) 10/11/2024 MNRubio,M.D. 54  Acute (Transient) Infections Poliovirus Infection – Viral spread to the nervous system may be secondary to viremia or occur by retrograde transport of the virus along axons of motor neurons – poliomyelitis that occur after vaccination are caused by mutations of the attenuated viruses to wild-type forms Diagnosis: – viral culture – PCR of throat secretions or stool – serology 10/11/2024 MNRubio,M.D. 55  Acute (Transient) Infections VIRAL HEMORRHAGIC FEVERS – systemic infections – caused by enveloped RNA viruses in four different families: Arenaviruses, filoviruses bunyaviruses, and flaviviruses – humans are not the natural reservoir for any of these viruses – viruses that cause hemorrhagic fever (Ebola, Marburg, Lassa) also can spread from person to person – hemorrhagic manifestations are due to thrombocytopenia or severe platelet or endothelial dysfunction 10/11/2024 MNRubio,M.D. 56  Acute (Transient) Infections VIRAL HEMORRHAGIC FEVERS increased vascular permeability may be necrosis and hemorrhage in many organs, particularly the liver most disease manifestations are related to activation of innate immune responses Viral infection of macrophages and dendritic cells leads to release of mediators that modify vascular function and have procoagulant activity 10/11/2024 MNRubio,M.D. 57  CHRONIC LATENT INFECTIONS (HERPESVIRUS INFECTIONS) 10/11/2024 MNRubio,M.D. 58  Latent Infections (Herpesvirus Infections) Latency - persistence of viral genomes in cells that do not produce infectious virus. viruses that most frequently establish latent infections in humans are herpesviruses. large encapsulated viruses with double-stranded DNA genomes that encode approximately 70 proteins. Herpesviruses cause acute infection followed by latent infection in which the viruses persist in a noninfectious form with periodic reactivation and shedding of infectious virus. 10/11/2024 MNRubio,M.D. 59  Latent Infections (Herpesvirus Infections) HSV-1 and HSV-2 differ serologically but are genetically similar and cause a similar set of primary and recurrent infections produce infectious virions and cause vesicular lesions of the epidermis In immunocompetent hosts, primary HSV infection resolves in a few weeks, although the virus remains latent in nerve cells HSV-1 is the major infectious cause of corneal blindness in the United States 10/11/2024 MNRubio,M.D. 60  Latent Infections (Herpesvirus Infections) Eight types of human herpesviruses, belonging to three subgroups that are defined by the type of cell most frequently infected and the site of latency: 1. α-group viruses: HSV-1 HSV-2 VZV which infect epithelial cells and produce latent infection in neurons 2. lymphotropic β-group viruses: CMV human herpesvirus-6 (exanthem subitum, also known as roseola infantum and sixth disease, a benign rash of infants) human herpesvirus-7 (a virus without a known disease association), which infect and produce latent infection in a variety of cell types) 3. the γ-group 10/11/2024 MNRubio,M.D. 61  Latent Infections (Herpesvirus Infections) MORPHOLOGY HSV-infected cells contain large, pink to purple intranuclear inclusions (Cowdry type A) that consist of intact and disrupted virions with the stained host cell chromatin pushed to the edges of the nucleus A herpesvirus blister showing glassy intranuclear viral inclusion bodies. 10/11/2024 MNRubio,M.D. 62 10/11/2024 MNRubio,M.D. 63  Latent Infections (Herpesvirus Infections) MORPHOLOGY Fever blisters or cold sores Gingivostomatitis Herpetic whitflow - Swollen, erythematous HSV lesions of the fingers or palm (infants / healthcare workers) Genital herpes Corneal lesions (herpes epithelial keratitis, herpes stromal keratitis) Herpes simplex encephalitis 10/11/2024 MNRubio,M.D. 64  Latent Infections (Herpesvirus Infections) MORPHOLOGY eczema herpeticum confluent, pustular, or hemorrhagic blisters, often with bacterial superinfection and viral dissemination to internal viscera Herpes esophagitis frequently complicated by superinfection with bacteria or fungi Herpes bronchopneumonia introduced by intubation of a patient with active oral lesions, is often necrotizing herpes hepatitis may cause liver failure 10/11/2024 MNRubio,M.D. 65  Latent Infections (Herpesvirus Infections) ▪ VARICELLA-ZOSTER VIRUS (VZV) ▪ Causes: ▪ 1. chickenpox 10/11/2024 MNRubio,M.D. 66 Skin lesion of chickenpox (varicella-zoster virus) with intraepithe- lial vesicle.  Latent Infections (Herpesvirus Infections) ▪ VARICELLA-ZOSTER VIRUS (VZV) ▪ Causes: ▪ 2. reactivation of latent VZV causes shingles (also called herpes zoster) ▪ Shingles occurs when VZV that has long remained latent in the dorsal root ganglia after a previous chickenpox infection is reactivated and infects sensory nerves that carry it to Dorsal root ganglion with varicella-zoster virus infection. Note the ganglion cell one or more dermatomes. necrosis and associated inflammation. 10/11/2024 MNRubio,M.D. 67  Latent Infections (Herpesvirus Infections) CYTOMEGALOVIRUS (CMV) – β-group herpesvirus, can produce a variety of disease manifestations, depending on the age of the host, and, more importantly, on the host’s immune status. CMV latently infects monocytes and their bone marrow progenitors and can be reactivated when cellular immunity is depressed. causes an asymptomatic or mononucleosis-like infection in healthy individuals but devastating systemic infections in neonates and in immunocompromised people 10/11/2024 MNRubio,M.D. 68  Latent Infections (Herpesvirus Infections) CYTOMEGALOVIRUS (CMV) CMV-infected cells exhibit gigantism of both the entire cell and its nucleus Within the nucleus is a large inclusion surrounded by a clear halo (owl's eye) 10/11/2024 Cytomegalovirus: distinct nuclear and MNRubio,M.D. ill-defined cytoplasmic inclusions in the lung. 69  Latent Infections (Herpesvirus Infections) CYTOMEGALOVIRUS (CMV) Transplacental transmission, from a newly acquired or primary infection in a mother who does not have protective antibodies (congenital CMV). Neonatal transmission, through cervical or vaginal secretions at birth, or later through breast milk from a mother who has active infection (perinatal CMV). Transmission through saliva during preschool years, especially in day care centers. Toddlers so infected readily transmit the virus to their parents. Transmission by the genital route is the dominant mode after about 15 years of age. Spread may also occur via respiratory secretions and the fecal-oral route 10/11/2024 MNRubio,M.D. 70  Latent Infections (Herpesvirus Infections) CYTOMEGALOVIRUS (CMV) ▪ Diagnosis of neonatal CMV is made by viral culture or PCR amplification of viral DNA in urine or saliva. 10/11/2024 Cytomegalovirus: distinct nuclear and MNRubio,M.D. ill-defined cytoplasmic inclusions in the lung. 71  CHRONIC PRODUCTIVE INFECTIONS 10/11/2024 MNRubio,M.D. 72 HEPATITIS B VIRUS member of the hepadnavirus family, is a DNA virus that can be transmitted percutaneously (intravenous drug use or blood transfusion), perinatally, and sexually infects hepatocytes, and cellular injury occurs mainly from the immune response to infected liver cells and not to cytopathic effects of the virus effectiveness of the cytotoxic T-lymphocyte (CTL) response is a major determinant of whether a person clears the virus or becomes a chronic carrier 10/11/2024 MNRubio,M.D. 73  TRANSFORMING INFECTIONS 10/11/2024 MNRubio,M.D. 74  TRANSFORMING INFECTIONS EPSTEIN-BARR VIRUS (EBV) causes infectious mononucleosis benign, self-limited lymphoproliferative disorder, and is associated with the development of a number of neoplasms, most notably certain lymphomas and nasopharyngeal carcinoma EBV is transmitted by close human contact, frequently through the saliva during kissing. EBV infects B cells and possibly epithelial cells of the oropharynx. An EBV envelope glycoprotein binds CD21 (CR2), the receptor for the C3d component of complement which is present on B cells. 10/11/2024 MNRubio,M.D. 75 EPSTEIN-BARR VIRUS (EBV) serious complication in those suffering from some form of immunodeficiency, such as AIDS, or receiving immunosuppressive therapy (e.g., bone marrow or solid-organ transplant recipients) is B-cell lymphomas also causes another distinctive form of lymphoma, called Burkitt lymphoma, particularly in certain geographic locales failure to control EBV infection - chronic infectious mononucleosis, agammaglobulinemia, and B-cell lymphoma, each of which proves fatal in about a third of patients. 10/11/2024 MNRubio,M.D. 76  Atypical lymphocytes in infectious mononucleosis. 10/11/2024 MNRubio,M.D. 77  BACTERIAL INFECTIONS 10/11/2024 MNRubio,M.D. 78  Gram-Positive Bacterial Infections Staphylococcus Streptococcus Enterococcus each of which causes many types of infections. First Diphtheria, listeriosis, anthrax, and nocardiosis are less common infections also caused by gram- positive rods and discussed here 10/11/2024 MNRubio,M.D. 79 Clinical or Microbiologic Frequent Disease Category Species Presentations Infections by pyogenic cocci Staphylococcus aureus, S. epidermidis Abscess, cellulitis, pneumonia, sepsis Streptococcus pyogenes Pharyngitis, erysipelas, scarlet fever Streptococcus pneumoniae Lobar pneumonia, meningitis (pneumococcus) Neisseria meningitidis Meningitis (meningococcus) Neisseria gonorrhoea (gonococcus) Gonorrhea Gram-negative infections Escherichia coli,[*] Klebsiella Urinary tract infection, wound pneumoniae[*] infection, abscess, pneumonia, Enterobacter (Aerobacter) aerogenes sepsis, shock, endocarditis [*] Proteus spp. (P. mirabilis, P. morgagni)[*] Serratia marcescens,[*] Pseudomonas spp. (P. aeruginosa)[*] Bacteroides spp. (B. fragilis) Anaerobic infection Legionella spp. (L. pneumophila) Legionnaires disease Contagious childhood bacterial Haemophilus influenzae Meningitis, upper and lower diseases respiratory tract infections Bordetella pertussis Whooping cough 10/11/2024 Corynebacterium diphtheriae MNRubio,M.D. Diphtheria 80 Clinical or Microbiologic Category Species Frequent Disease Presentations Enteric infections Enteropathogenic E. coli, Shigella spp. Invasive or noninvasive gastroenterocolitis Vibrio cholerae, Campylobacter jejuni, C. coli Yersinia enterocolitica, Salmonella spp. (1000 strains) Salmonella typhi Typhoid fever Clostridial infections Clostridium tetani Tetanus (lockjaw) Clostridium botulinum Botulism (paralytic food poisoning) Clostridium perfringens, C. septicum Gas gangrene, necrotizing cellulitis Clostridium difficile[*] Pseudomembranous colitis Zoonotic bacterial infections Bacillus anthracis Anthrax Yersinia pestis Bubonic plague Francisella tularensis Tularemia Brucella melitensis, B. suis, B. abortus Brucellosis (undulant fever) Borrelia recurrentis Relapsing fever Borrelia burgdorferi Lyme disease Human treponemal infections Treponema pallidum Syphilis Mycobacterial infections Mycobacterium tuberculosis,[*] M. Tuberculosis bovis M. leprae Leprosy M. kansasii,[*] M. avium, M. Atypical mycobacterial infections intracellulare Actinomycetaceae Nocardia asteroides[*] Nocardiosis 10/11/2024 MNRubio,M.D. Actinomyces israelii Actinomycosis 81  GRAM-POSITIVE BACTERIAL INFECTIONS 10/11/2024 MNRubio,M.D. 82  STAPHYLOCOCCAL INFECTIONS Staphylococcus aureus - pyogenic gram-positive cocci that form clusters like bunches of grapes cause a myriad of skin lesions (boils, carbuncles, impetigo, and scalded-skin syndrome= Ritter dse. ) as well as abscesses, sepsis, osteomyelitis, pneumonia, endocarditis, food poisoning, and toxic shock syndrome (TSS) Hydradenitis suppurativa Paronychia Felons Staphylococcal lung imnfection Staphylococcal scalded-skin syndrome 10/11/2024 MNRubio,M.D. 83 10/11/2024 MNRubio,M.D. 84  STAPHYLOCOCCAL INFECTIONS Factors influencing their virulence 1. Surface receptors for fibrinogen (called clumping factor), fibronectin, vitronectin).. Bind with endothelial cells 2. Lipase of S. a. degrades lipids on the skin surface >> abscesses 3. Protein A on the surface binds the Fc portion of immunoglobulins, allowing the organism to escape antibody-mediated killing. 4. Polysaccaharide capsule – allow them to attach to artificial materials, resist phagocytosis 10/11/2024 MNRubio,M.D. 85  STAPHYLOCOCCAL INFECTIONS Bacterial toxins produced 1. Membrane-damaging (hemolytic0) toxins – α-toxin, a pore-forming protein that intercalates into the plasma membrane of host cells and depolarizes them – β-toxin - sphingomyelinase – δ-toxin - detergent-like peptide – Staphylococcal γ-toxin lyse erythrocyte – Leukocidin lyse phagocytic cells 10/11/2024 MNRubio,M.D. 86  STAPHYLOCOCCAL INFECTIONS Bacterial toxins produced 1. Membrane-damaging (hemolytic0) toxins 2. Exfoliative A and B toxins – – serine proteases, cleave the protein desmoglein 1, (part of the desmosomes that hold epidermal cells tightly together) – causes keratinocytes to detach from one another and the underlying skin – Exfoliation can occur: locally at the site of infection (bullous impetigo) widespread, when secreted toxin causes disseminated loss of the superficial epidermis (staphylococcal scalded-skin syndrome) 10/11/2024 MNRubio,M.D. 87  STAPHYLOCOCCAL INFECTIONS Bacterial toxins produced 1. Membrane-damaging (hemolytic0) toxins 2. Exfoliative A and B toxins – 3. Superantigens – cause food poisoning and TSS – staphylococcal skin infections are centered around the hair follicles 10/11/2024 MNRubio,M.D. 88  Streptococcal and Enterococcal Infections Streptococci cause suppurative infections of the skin, oropharynx, lungs, and heart valves. responsible for a number of postinfectious syndromes: – rheumatic fever – immune complex glomerulonephritis – erythema nodosum 10/11/2024 MNRubio,M.D. 89 Streptococcal and Enterococcal Infections S. pyogenes (group A) - pharyngitis, scarlet fever, erysipelas, impetigo, rheumatic fever, TSS, and glomerulonephritis S. agalactiae (group B) – colonizes the female genital tract – causes sepsis and meningitis in neonates and chorioamnionitis in pregnancy S. pneumoniae, the most important α-hemolytic streptococcus – common cause of community-acquired pneumonia and meningitis in adults 10/11/2024 MNRubio,M.D. 90 Streptococcal and Enterococcal Infections viridans group streptococci – several species of α-hemolytic and nonhemolytic streptococci that are normal oral flora and are also a common cause of endocarditis S. mutans - major cause of dental caries Enterococci - gram-positive cocci that grow in chains; significant cause of endocarditis and urinary tract infections 10/11/2024 MNRubio,M.D. 91  GRAM-POSITIVE BACTERIAL INFECTIONS 10/11/2024 MNRubio,M.D. 92  Streptococcal and Enterococcal Infections Erysipelas caused by exotoxins from superficial infection with S. pyogenes characterized by rapidly spreading erythematous cutaneous swelling that may begin on the face or, less frequently, on the body or an extremity rash has a sharp, well-demarcated, serpiginous border and may form a “butterfly” distribution on the face histologic examination - diffuse, edematous, neutrophilic inflammatory reaction in the dermis and epidermis extending into the subcutaneous tissues Erysipelas 10/11/2024 MNRubio,M.D. 93  DIPTHERIA Cause: Corynebacterium diphtheriae Char: slender gram-positive rod with clubbed ends MOT: from person to person through aerosols or skin exudate Patho: – produces a phage-encoded A-B toxin that blocks host cell protein synthesis. – Release of exotoxin > necrosis of the epithelium, accompanied by an outpouring of a dense fibrinosuppurative exudate > coagulation of this exudate on the ulcerated necrotic surface > creates a tough, dirty gray to black, superficial membrane, sometimes called pseudo-membrane because it is not formed by viable tissue. 10/11/2024 MNRubio,M.D. 94  LISTERIOSIS Cause: Listeria monocytogenes is a gram-positive bacillus that causes severe food-borne infections in vulnerable hosts/facultative intracellular pathogen. Pregnant women: – amnionitis > abortion/stillbirth/neonatal sespsis Neonates and immunosuppressed adults > disseminated disease (granulomatosis infantiseptica of the newborn) and exudative meningitis Patho: 10/11/2024 MNRubio,M.D. 95  ANTHAX Cause: Bacillus anthracis – large, spore-forming gram-positive rod-shaped bacterium MOT: eating or handling meat or products (e.g., wool or hides) from infected animals. Disease: Anthrax - characterized by necrotizing inflammatory lesions in the skin or gastrointestinal tract or systemically. Major forms: – 1. Cutaneous anthrax – black eschar, dries > falls off – 2. Inhalational anthrax RI > bacteremia /(> meningitis) > shock >death – 3. Gastrointestinal anthrax – severe bloody diarrhea / bacteremia > death 10/11/2024 MNRubio,M.D. 96  ANTHAX Bacillus anthracis in the subcapsular sinus of a hilar lymph node of a 10/11/2024 patient who died of inhalational anthrax. MNRubio,M.D. 97  NOCARDIA Cause: Nocardia asteroides aerobic gram-positive bacteria found in soil that cause opportunistic infections. Morphologically similar to molds, but true bacteria Patho: cause respiratory infection to immunocompromised patients (prolonged steroid use, HIV, DM) 10/11/2024 MNRubio,M.D. 98  GRAM-NEGATIVE BACTERIAL INFECTIONS 10/11/2024 MNRubio,M.D. 99  Neisserial Infection gram-negative diplococci that are flattened on the adjoining sides, giving the pair the shape of a coffee bean. aerobic bacteria have stringent nutritional requirements and grow best on enriched media such as lysed sheep’s blood agar. two clinically significant Neisseria are N. meningitidis and N. gonorrhoeae. 10/11/2024 MNRubio,M.D. 100  Neisserial Infection N. meningitidis significant cause of bacterial meningitis, particularly among children younger than 2 years of age N. gonorrhoeae important cause of sexually transmitted disease (STD) Untreated infection can lead to pelvic inflammatory disease, which can cause infertility or ectopic pregnancy Neonatal N. gonorrhoeae infection causes blindness and, rarely, sepsis 10/11/2024 MNRubio,M.D. 101  PERTUSSIS ( WHOOPING COUGH) Cause: Bordetella pertussis is an acute, highly communicable illness characterized by paroxysms of violent coughing followed by a loud inspiratory “whoop.” Patho: – colonizes the brush border of the bronchial epithelium and also invades macrophages – contains a filamentous hemagglutinin + carbohydrates on the surface of respiratory epithelial cells, as well as to CR3 (Mac-1) integrins on macrophages. – toxin is a typical A-B toxin that is composed of five sub- units. Produces toxic adenylate cyclase >  cAMP ➔ Oxidative burst of neutrophils and appoptosis of macrophages 10/11/2024 MNRubio,M.D. 102 10/11/2024 MNRubio,M.D. 103  Pseudomonas Infection Cause: Ps. Aeruginosa – gram-negative bacillus – frequent, deadly pathogen of people with cystic fibrosis, severe burns, or neutropenia – Resistant to antibiotics > diff to tx common cause of hospital-acquired infections causes corneal keratitis in wearers of contact lenses endocarditis and osteomyelitis in intravenous drug abusers, external otitis (swimmer's ear) in healthy individuals, and severe external otitis in diabetics 10/11/2024 MNRubio,M.D. 104  Pseudomonas Infection Patho: – 1. A-B exotoxin A > inhibits protein synthesis by ADP-ribosylating the ribosomal protein EF-2, leading to the death of host cells. – 2. damaging enzymes that destroy extracellular matrix (elastase), kill leukocytes (leukocidin), and destroy cell membranes (hemolysins) – secretes a mucoid exopolysaccharide called alginate, which forms a biofilm that protects bacteria from antibodies, complement, phagocytes, and antibiotics (lungs of C)F. rapidly develops antibiotic resistance through other mechanisms as well, making treatment difficult. 10/11/2024 MNRubio,M.D. 105  Pseudomonas Infection Diseases: Necrotizing Pneumonia Ecthyma gangrenosum Bacterial vasculitis aPseudomonas vasculitis in which masses of organisms form a perivascular blue haze 10/11/2024 MNRubio,M.D. 106  PLAGUE (Black Death) The distinctive histologic features include (1) massive proliferation of the organisms (2) early appearance of protein-rich and polysaccharide- rich effusions with few inflammatory cells (3) necrosis of tissues and blood vessels with hemorrhage, thrombosis, and marked tissue swelling (4) neutrophilic infiltrates that accumulate adjacent to necrotic areas as healing begins 10/11/2024 MNRubio,M.D. 107  PLAGUE (Black Death) Cuase: Y. pestis – gram-negative facultative intracellular bacterium MOT: fleabite, aerosols Starving flea bites and regurgitates > infects humans > spread to lymphatic tissues, proliferate > inhibits human from mounting an effective response >Yop virulon, which encodes a type III secretion system, a hollow syringe-like structure that projects from the bacterial surface > binds to host cells > injects bacterial proteins, called Yops (Yersinia outercoat proteins), into the cell > YopE, YopH, and YopT inactivate molecules that regulate actin polymerization > blocks phagocytosis. YopJ inhibits the signaling pathways that are activated by LPS > blocking the production of inflammatory cytokines. 10/11/2024 MNRubio,M.D. 108  CHANCROID (SOFT CHANCRE) Cause: Hemophilus ducreyi Chancroid is an acute, sexually transmitted, ulcerative infection inoculation > 4 – 7 days > tender, erythematous papule involving the external genitalia > surface of the primary lesion erodes to produce an irregular ulcer, which is more apt to be painful in males than in females > base of the ulcer is covered by shaggy, yellow-gray exudate In untreated cases the inflamed and enlarged nodes (buboes) > chronic, draining ulcers 10/11/2024 MNRubio,M.D. 109  CHANCROID (SOFT CHANCRE) Histo: ulcer of chancroid contains a superficial zone of neutrophilic debris and fibrin, with an underlying zone of granulation tissue containing areas of necrosis and thrombosed vessels 10/11/2024 MNRubio,M.D. 110  GRANULOMA INGUINALE (DONOVANOSIS) CAUSE: Klebsiella granulomatis (formerly called Calymmato- bacterium donovani) Causes sexually transmitted chronic inflammatory disease Untreated cases - development of extensive scarring, often associated with lymphatic obstruction and lymphedema (elephantiasis) of the external genitalia. begins as a raised papular lesion on the moist stratified squamous epithelium of the genitalia or, rarely, the oral mucosa or pharynx > ulcerates > dev abundant granulation tissue > protuberant soft, painless mass. 10/11/2024 MNRubio,M.D. 111  MYCOBACTERIA 10/11/2024 MNRubio,M.D. 112  TUBERCULOSIS MOT: person to person via airborne mode PATHO: Primary TB Inhaled bacilli > lower part of upper lobe/upper part of the lower lobe > sensitization dev > 1 – 1.5 cm area of gray-white inflammation with consolidation (Ghon complex – parenchymal lesion and LN) > caseous necrosis of the center 10/11/2024 MNRubio,M.D. 113  central caseation surrounded by epithelioid and multinucleated giant cells. 10/11/2024 sheets MNRubio,M.D. of foamy macrophages are seen114that are packed with mycobacteria  TUBERCULOSIS Secondary TB Initial lesion: small focus of consolidation, less than 2 cm in diameter, within 1 to 2 cm of the apical pleura sharply circumscribed, firm, gray-white to yellow areas that have a variable amount of central caseation and peripheral fibrosis 10/11/2024 MNRubio,M.D. 115  TUBERCULOSIS Milliary pulmonary TB - occurs when organisms draining through lymphatics enter the venous blood and circulate back to the lung Systemic miliary - tuberculosis occurs when bacteria disseminate through the systemic arterial system ( liver, spleen, BM, adrenals, meningers etc). 10/11/2024 MNRubio,M.D. 116  TUBERCULOSIS Lymphadenitis is the most frequent presentation of extra- pulmonary tuberculosis, usually occurring in the cervical region (“scrofula”). 10/11/2024 MNRubio,M.D. 117  LEPROSY Cause: Mycobacterium leprae – mainly affects the skin and peripheral nerves and results in disabling deformities Tuberculoid leprosy localized flat, red skin lesions that enlarge and develop irregular shapes with indurated, elevated, hyperpigmented margins and depressed pale centers (central healing) Neuronal involvement dominates tuberculoid leprosy aneshesia 10/11/2024 MNRubio,M.D. 118  Contractures, paralyses, and autoamputation of fingers or toes may ensue Facial nerve involvement > paralysis of the eyelids, with keratitis and corneal ulcerations all sites of involvement have granulomatous lesions closely resembling those found in tuberculosis, and bacilli are almost never found, hence the name “paucibacillary” leprosy 10/11/2024 MNRubio,M.D. 119  LEPROSY Lepromatous leprosy – involves the skin, peripheral nerves, anterior chamber of the eye, upper airways (down to the larynx), testes, hands, and feet – vital organs and CNS are rarely affected – lesions contain large aggregates of lipid-laden macrophages (lepra cells), often filled with masses (“globi”) of acid-fast bacilli – Because of the abundant bacteria, lepromatous leprosy is referred to as “multibacillary 10/11/2024 MNRubio,M.D. 120 10/11/2024 MNRubio,M.D. 121 10/11/2024 MNRubio,M.D. 122  SPIROCHETES 10/11/2024 MNRubio,M.D. 123  SPIROCHETES Chancre - red lesion located at the site of treponemal invasion on the penis, cervix, vaginal wall, or anus. Secondary – condylomata lata (broad-based, elevated plaques). Beningn tertiary Syphilis – gummas (nodular lesions related to the development of delayed hypersensitivity to the bacteria) in bones, skin, mucus membranes of the upper airway and mouth. 10/11/2024 MNRubio,M.D. 124 10/11/2024 MNRubio,M.D. 125  Treponema pallidum (Steiner silver stain) showing several spirochetes in histologic sections of placental syphilis. 10/11/2024 MNRubio,M.D. 126  ANAEROBIC BACTERIA 10/11/2024 MNRubio,M.D. 127  Clostridial Infections C. perfringens, C. septicum cause cellulitis and myonecrosis of traumatic and surgical wounds (gas gangrene), uterine myonecrosis often associated with illegal abortions, mild food poisoning, and infection of the small bowel associated with ischemia or neutropenia that often leads to severe sepsis 10/11/2024 MNRubio,M.D. 128  Clostridial Infections C. Tetani cause of tetanus proliferates in puncture wounds and in the umbilical stump of newborn infants and releases a potent neurotoxin, called tetanospasmin, that causes convulsive contractions of skeletal muscles (lockjaw) 10/11/2024 MNRubio,M.D. 129 Clostridial Infections C. botulinum grows in inadequately sterilized canned foods and releases a potent neurotoxin that blocks synaptic release of acetylcholine and causes a severe paralysis of respiratory and skeletal muscles (botulism) C. difficile overgrows other intestinal flora in antibiotic-treated people, releases toxins, and causes pseudomembranous colitis 10/11/2024 MNRubio,M.D. 130 10/11/2024 MNRubio,M.D. 131  OBLIGATE INTRACELLULAR BACTERIA 10/11/2024 MNRubio,M.D. 132 Chlamydial Infections Chlamydia trachomatis – small gram-negative bacterium that is an obligate intracellular parasite – Genital infection by C. trachomatis is the most common sexually transmitted bacterial disease in the world – Genital infection with the L serotypes of C. trachomatis causes lymphogranuloma venereum, a chronic, ulcerative disease – initially manifests as a small, often unnoticed, papule on the genital mucosa or nearby skin – Two to six weeks later, growth of the organism and the host response in draining lymph nodes produce swollen, tender lymph nodes, which may coalesce and rupture 10/11/2024 MNRubio,M.D. 133  THANK YOU This PPT was prepared by GenPath and Histopath Professors- Rubio, Ahmad, Pagud, and Maria Jose. Updated by the current cluster.