Pathology and Medical Parasitology Lecture Notes PDF

Field of Medicine Medicine and Surgery Program Lecture 1: Introduction to Pathology. Cellular Responses and Cellular Adaptations Prof : Mohammed Faisal Date : 12 / 2 /2022  Lecture Objectives 1.Introduction to Pathology. 2.Describe cellular Responses. 3.Discuss ce...

Field of Medicine Medicine and Surgery Program Lecture 1: Introduction to Pathology. Cellular Responses and Cellular Adaptations Prof : Mohammed Faisal Date : 12 / 2 /2022  Lecture Objectives 1.Introduction to Pathology. 2.Describe cellular Responses. 3.Discuss cellular Adaptations to Stress. 4.Discuss hypertrophy and Hyperplasia.  INTRODUCTION 12:49  PATHOLOGY Pathology is scientific study of disease. It includes functional & structural changes, from molecular level to effects on individual. 12:49  STAGES: 1. General pathology: study of main types of disease process: inflammation, tumors etc. 2. Systematic pathology: study of specific organ or system diseases e.g. Lung cancer. 12:49  Characteristics of disease: 1. Epidemiology (incidence). 2. Aetiology (cause). 3. Pathogenesis (mechanism). 4. Morphological, functional & clinical changes. 5. Complications & sequelae. 6. Prognosis (outcome). 12:49  Epidemiology: 1.Distribution & determinants of a disease in different populations. 12:49  Aetiology: o Diseases can be caused by: 1. Genetic abnormalities. 2. Environmental factors: infective agents, chemicals, radiation & mechanical trauma. o Multifactorial aetiology: Some diseases can be caused by combination of factors. o Unknown cause (Primary, idiopathic, cryptogenic). o Risk factors: Sometimes exact etiology of disease is not known, but disease is observed more commonly in people with  Certain traits (e.g. certain blood type), occupations or habits.  Other risk factors may facilitate development of disease e.g. malnutrition facilitates infection. 12:49  Pathogenesis: 1.It is mechanism by which aetiology operates to produce disease. 12:49  Morphological changes: o Lesion: is structural abnormality seen in organ in disease e.g. a mass, ulcer etc... o Structural changes can be detected by:  Gross examination of organs (surgical or postmortem at autopsy), or  Light or electron microscopy. 12:49 12:49  Complications & sequelae: Diseases may have secondary effects e.g. spread of infection to distant site & tumor →→ intestinal obstruction. 12:49  Prognosis: It usually describes well known fate, if disease is allowed to follow its natural course. It is subjected to change by medical or surgical intervention. 12:49 12:49  General classification of diseases Based on pathogenesis Congenital Acquired Genetic Inflammatory Non Genetic Hemodynamic Growth disorder Disordered immunity Metabolic and degenerative disease 12:49  True or False Pathology deals with all aspects of the disease including treatment. CELLULAR RESPONSE TO INJURY  Responses: Changes in cell but cell remains viable in face of exogenous stimuli. Adaptation Includes: a) Atrophy. b) Hypertrophy. c) Hyperplasia. d) Metaplasia. Pathologic changes in cell that can be restored if stress is removed or Reversible mild. injury Permanent pathologic changes in cell that cause cell death. Irreversible Occurs when stress exceed capacity of cell to adapt. injury  Hypertrophy Def: ↑↑ size & weight of organ due to ↑↑ in size of its cells, which have synthesized actively metabolic structural components, necessary for increasing metabolism. Types: 1. Physiological: Pregnant uterus due to hormone stimulation & muscle hypertrophy in athletes. 2. Pathological: a) Adaptive type: affects muscle coat of hollow organs due to ↑↑ intra-luminal pressure e.g. Left ventricular hypertrophy due to hypertension or aortic valve stenosis. Urinary bladder hypertrophy due to stricture of bladder neck. b) Compensatory type: If one of a paired organ is out of function or surgically removed, other organ undergoes compensatory hypertrophy e.g. kidney enlargement when the other kidney is surgically removed. 12:49  Hyperplasia Def: ↑↑ size & weight of organ due to ↑↑ in number of its cells (↑↑ cell division). It can occur in any cell type capable of division. It is precancerous. Types: 1. Physiological: a. Hormonal hyperplasia e.g. mammary glands & genitalia at puberty due to estrogen stimulation. b. Compensatory e.g. bone marrow hyperplasia after hemorrhage. 2. Pathological: a. Hormonal hyperplasia e.g. endometrial hyperplasia in repeated anovulatory cycles & benign prostatic hyperplasia due to estrogen stimulation. b. Lymphoid hyperplasia in response to antigenic stimulation. 12:49  True or False Left ventricular hypertrophy due to hypertension or aortic valve stenosis is an example of pathological hypertrophy.  SUMMARY We have discussed: Introduction to Pathology. Cellular Responses. Cellular Adaptations to Stress. Hypertrophy. Hyperplasia. Faculty of Medicine Medicine and Surgery Introduction to Medical Parasitology part 1 Dr : Shereen Mahmoud Date: / 2 /2025  Introduction Medical parasitology: It is the science which deals with the parasites that infect man and the diseases caused by them  Parasite: Is an organism, which lives at the expense of another one called host.  Host: Is a living organism that harbors the parasite. The relationship between the organism and its host occurs in the following forms:- 1) Commensalism: It is a relationship between two living organisms where one benefits (commensal), while the other (host) is not harmed. 2) Parasitism: It is a relationship between two living organisms where one benefits (parasite), while the other (host) is harmed. 3) Mutualism: It is a beneficial relationship between two living organisms where both drive a benefit and can successfully live apart. 4) Symbiosis: It is a close and long term beneficial relationship between two living organisms where both drive a benefit and cannot live apart. Types of hosts:- 1) Definitive host (D.H): The host which harbors the mature or adult stage of the parasite or in which sexual reproduction of the parasite takes place. 2) Intermediate host (I.H): It is the host which harbors immature or larval stage (or non-sexually reproducing forms of the parasites). 3) Reservoir host (R.H): An animal that harbors the mature stage of the parasite as in human. It acts also as a source of infection to man and maintains the parasite in nature. 4) Vector: An arthropod which carries the parasite from one host to another. Types of parasites:- 1) Accidental parasite: Parasite which infects an unusual host. 2) Facultative parasite: An organism which may either live as parasitic form or as free living form. 3) Obligatory parasite: The parasite which cannot exist without a host, entirely dependent upon a host for its survival. 4) Ectoparasite: parasite that lives on or in the skin (outer surface of the host) (infestation). e.g. lice, ticks. 5) Endoparasite: parasite that lives within the host (internal organs or tissues of its host) (infection). Most of helminthic parasites causing human disease are Endoparasites. 6) Temporary or intermittent parasite: a parasite that visits its host only for a short period of time for its meal. 7) Permanent parasite: a parasite that lives its entire life within or on a host. 8) Opportunistic parasite: a parasite that causes aggressive disease in immunodeficient patients (AIDS), while in immunocompetent individuals, the parasite may exist in a latent form producing no or mild symptoms. 9) Coprozoic or spurious parasite: Foreign organism that passes through the human intestine without causing any disease and is detected in the stool after ingestion. Parasite transmission Includes: 1) Hosts: D.H, I.H, R.H and Vectors if present 2) Stages: I.S and D.S. 3) Habitat. 4) Mode of infection. Terms used in parasitology:- Habitat: The final organ or site where the parasite lives in the definitive host. Infective stage (I.S): The stage by which the infection takes place.  Diagnostic stage (D.S): The stage by which we can diagnose the parasitic infection (disease).  Carrier: A host in a state of equilibrium with the parasite without or with minimal symptoms of the disease, but he is infective to others.  Zoonosis: Transmission of infection from animal to man either directly or indirectly via an intermediate host. Endemicity: Steady or relativity moderate level of parasitic infection among the population who has a certain degree of resistance and the parasite is common and well known to them. Epidemicity: Fulminating outbreak of a parasitic disease from a new parasite not common to the population who has little resistance. The route of parasite transmission (mode of infection): 1) Direct contact through the skin. 2) Ingestion of contaminated food (vegetables, undercooked meat, and fish) or drinking water containing the infective stage (Foeco oral route). 3) Inhalation of dust carrying the infective stage of the parasite. 4) Penetration of the skin due to contact with infected soil or water stream. 5) Congenital from mother to fetus (transplacental) or maybe trans mammary (mother`s milk). 6) Sexual contact. 7) Autoinfection (either external or internal). 8) Vectors, through bite or feces of infected vector or by swallowing or crushing the vector. 9) Blood transfusion or through iatrogenic e.g. contaminated syringes. 10) Organ transplantation. 11) Nosocomial after admission to the hospital. Types of Parasites Life Cycles: 1- Direct life cycle: When a parasite requires only a single host to complete its development. e.g. Ancylostoma duodenale. 2- Indirect life cycle: When a parasite requires 2 or more species of the host to complete its development. e.g. Heterophys heterophys.  Faculty of Medicine Medicine and Surgery Introduction to Medical Parasitology Part 2 Date : /2 /2025 Dr : Shereen Mahmoud  Introduction to Medical Parasitology 2 Pathogenesis of parasitic infection - Occurs through one or more of the following:- 1) Mechanical: The parasite may obstruct normal passage like intestine or bile tract. 2) Traumatic :- - External due to invasion of the skin. - Internal by attachment to intestinal mucosa by buccal capsule or teeth producing ulcers. 3) Toxin production: Circulation of parasitic products like saliva or excreta. 4) Tissue damage and necrosis: Due to enzymes secreted by parasites. 5) Cellular destruction: As RBCs or reticuloendothelial system (RES) damage e.g.: Malaria. 6) Immune stimulation: Parasitic antigens produce humoral and/or cellular immune response → allergic reaction or formation of fibrous encapsulation around parasites e.g.: Bilharzial granuloma  Clinical manifestations and presentation of parasitic infections A wide variety of representative symptoms, may occur when a parasite infects a human host ranging from asymptomatic to severe symptoms that may result in death. The most observed symptoms include diarrhea, abdominal pain, and abdominal cramping. Other symptoms, such as elephantiasis in filariasis (an enlargement of areas such as the breast, leg, and scrotum caused by a parasite’s presence), anemia, vitamin deficiency, bowel obstruction, edema, enlargement of major organs, skin lesions, and blindness, may develop.  Immune response to parasitic diseases  Like other infectious agents, parasites also elicit immune responses in the host, both humoral as well as cellular.  But immunological protection against parasitic infections is much less efficient than it is against bacterial or viral infections.  Immune response to helminths:  Helminths are eliminated mainly by Ig E antibody and eosinophil-mediated killing as well as by other leukocytes.  Phagocytes also attack helminthic parasites and secrete microbicidal substances to kill organisms that are too large to be phagocytosed.  Defense against many helminthic infections is mediated by the activation of TH2 cells, which results in the production of Ig E antibodies and the activation of eosinophils and mast cells ADCC (Antibody Dependant Cell mediated Cytotoxicity).  Most parasitic infections are chronic because of weak innate immunity and the ability of parasites to evade or resist elimination by adaptive immune responses Immune response to protozoa: Protozoa that live within host cells are destroyed by cell-mediated immunity. The principal innate immune response to protozoa is phagocytosis, but many of these parasites are resistant to phagocytic killing and may even replicate within macrophages.  Immune Evasion of Parasites Parasites can evade the immune system in a variety of mechanisms: Sequestration: parasites can hide away from the immune system by invading immune-privileged tissue such as the central nervous system. Parasites shedding their surface Antigens as the T-cells and antibodies of the host immune system can not recognize their epitopes (the antigenic surface of a parasite). Antigenic variation: Parasites can also evade by mutation of their epitopes. Molecular Mimicry: The presence of host (or host-like) molecules on the parasite surface. Immune suppression: as suppression of bone marrow in Leishmania infections. Immune Evasion of Parasites  Difficulty of Anti-parasitic vaccine development No effective vaccine for humans has so far been developed against parasites due to: Their complex life cycles. Antigenic variation. The difficulty in developing vaccines against parasitic diseases is to identify (and produce) appropriate protective antigens. Lack of animal models.  However trials using anti-parasite vaccination under experimental conditions clearly demonstrate a certain level of clinical immunity against Malaria, Bilharziasis, and Leishmaniasis.  Diagnosis of parasitic infections I. History II. Clinical diagnosis:- (symptoms and signs) Depends on the characteristics of the related parasitic infection. e.g.: abdominal pain, diarrhea in intestinal parasitic infection. e.g.: elephantiasis in the case of Filariasis. III. Laboratory diagnosis:  1) Direct diagnosis:- A. Microscopically examination B. b. Culture of stool or soil. C. c. Animal inoculations. D. Detection of parasitic coproantigens. Microscopically examination: An appropriate clinical specimen should be collected for a definitive diagnosis of parasitic infections. The following specimens (samples) are usually examined to establish a diagnosis: Stool Urine Blood Sputum Cerebrospinal fluid (CSF) Tissue and aspirates Genital specimens Microscope 2) Indirect diagnosis:- - Used when parasites are present in tissues or in cases of chronic infection. a. Intradermal test by injection of specific antigen intradermal in one forearm and saline in other forearm (as control); cross-reactivity is the main disadvantage. b. Detection of antibodies in the patient's serum by serological test as indirect haemagglutination test (IHAT), complement fixation test (CFT), enzyme-linked immunosorbent assay (ELISA), and indirect immunofluorescent antibody test (IFAT). c. Detection of parasitic circulating antigens. IV- Imaging and Radiology: Imaging procedures like X-ray, ultrasonography (U/S) computed tomography (CT) scan and magnetic resonance Imaging (MRI) are now being extensively used for diagnosing various parasitic infections. V- Molecular methods:- Polymerase chain reaction (PCR): This depends on the ability of amplification of single DNA of the parasite in the presence of polymerase enzyme.It is very sensitive and specific. VI-Hematology and Biochemical diagnosis: Anemia is frequently seen in hookworm infection and Malaria. Eosinophilia is frequently present in helminthic infections. Leukocytosis is seen in amoebic liver abscess.  Treatment Treatment lines of Parasitic Infections: 1. Medical 2. Surgical. 3. Chemotherapy: There are a variety of anti- parasitic medications available. 4. Symptomatic, bed rest and Adequate nutrition as vitamin supplements, fluid replacement. 5. Treatment of complications and Blood transfusion  Prevention and Control 1. Health Education about the mode of infection by different parasites. 2. Destruction and/or control of reservoir hosts and vectors of different parasites. 3. Good personal hygiene e.g., hand washing before eating and after defection. 4. Reduction in sources of infection and Treatment of cases. 5. Proper washing of green vegetables and proper cooking of food e.g.: meat & fish. 6. Proper water supply. 7. Use of insecticides if it is arthropods transmitted parasites. 8. Use of protective clothing & Use of protective window and bed nets. Faculty of Medicine Medicine and Surgery Trematodes and Cestodes Dr : Shereen Mahmoud Date: / 2 /2025  Classification of Medical Parasites Parasitology is classified into three main groups: Protozology: the Study of protozoa. (proto = primitive zoa = animal) Helminthology: the study of helminth. (Helminth = Worm) Entomology: the study of arthropods. Nomenclature (Taxonomy) of parasites:- - Name of genus begins with a capital letter. - Name of species begins with small letter e.g. Fasciola hepatica or F. hepatica and they are written in italics or underlined. Classification of Helminths Helminths Platyhelminths Nemathelminths Flat Worms Round Worms Class Trematoda Class Cestoda Class Nematoda Flukes Tape worms  Phylum : Platyhelminthes (Flat worms) Class : Trematoda (Flukes) Helminths General characters :- 1) The body is generally flattened, leaf-like and unsegmented except for female Schistosoma which are cylindrical. 2) They are bilaterally symmetrical. 3) The body covered with cuticle for protection. 4) Organs of fixation (suckers) :- a. Oral sucker at the anterior end around the mouth. b. Ventral sucker (on ventral surface) usually larger than the oral sucker. c. Genital sucker (may present in some species). 5) Digestive system consists of:- Mouth at the anterior portion surrounded by the oral sucker. Esophagus with muscular pharynx (except for Schistosoma, in which pharynx is absent) that bifurcates in front of the ventral sucker into two intestinal caeca. Intestinal caeca end blindly (no anus). Remains of food are got ride through the mouth (vomited). 6) Excretory system: Bilaterally symmetrical flame cells → collecting tubules which collect fluid → bladder → excretory pore posteriorly. 7) Genital system:- Hermaphrodite except Schistosoma. Male organs: Usually 2 testes vary in shape → 2 vasa efferentia → vas deferens → open in common genital pore anterior to female opening. Female organs: A single ovary → short oviduct → ootype → uterus → vagina → common genital pore posterior to male opening. 8) The eggs of trematodes: are operculated (except for schistosomes), usually, they pass mature with miracidium inside (Schistosoma and Heterophyes) or pass immature (Fascolia) and need water to hatch. 9) Life cycle of all trematodes passes through sexual development inside the definitive host and asexual development inside the intermediate host (snail). Inside the snail, miracidium develops asexually → sporocyst → daughter sporocyst → redia → cercaria, except schistosomes (no redia stage).  Trematodes cercaria Cercaria body consists of : 1- head 2- tail: according to the shape of the tail, they are divided into the following types: Types of cercaria: 1- Leptocercus cercaria : It has simple tail e.g. Fascolia cercaria. 2- Lophocercus cercaria: It has a membrane around its tail e.g. Heterophyes heterophyes cercaria. 3- Microcercus cercaria: It has short knob like tail e.g. Paragonimus cercaria. 4- Frucocercus cercaria: It has forked tail e.g. Schistosoma cercaria. Classification of Trematodes according to Habitat:-  Hepatic flukes :- - Fasciola gigantica. Fasciola hepatica. Intestinal fluke :- Heterophyes heterophyes.  Lung fluke :- Paragonimus westermani.  Blood flukes :- - Schistosoma mansoni. - Schistosoma haematobium. Class : Cestoda (Tapeworms)  General Characters :- Class : Cestoda (Tapeworms) 1) Adults: Flat, ribbon like, and segmented. 2) Their length varies from a few millimeters to several meters. 3) The body is formed of:- 1. Scolex (head) with organs of fixation:- - Suckers either:- 4 true cup-shaped muscular suckers or 2 false suckers as grooves (bothria). - Rostellum with one or more circles of hooks. Fig.(7 - 2) 2. Neck is the region of growth. 3. Strobila: Formed of segments (proglottids). Immature segments: contain immature genital organs. Mature segments: contain fully developed genital organs. Gravid segments: contain uteri filled with eggs.  Classification of Cestoda (Tapeworms) N.B: Cestodes has no body cavity It has no digestive system, nutrition Class Cestoda is absorbed through the tegument cyclophyllidae Pseudophyllidae No Gravid segments Gravid segments  General Characters :- 4) The genital system :- Cestodes are also hermaphrodites having both male and female genital systems in each mature segment. Male organs: Testes (at least 3, small scattered) → vasa efferentia → vas deferens → seminal vesicle → ejaculatory duct → common genital pore. Female organs: Bilobed ovary in the posterior part of the segment → oviduct → ootype → uterus → vagina open in common genital pore. - Uterus : Either vertical or transverse, blind or with a separate pore. - Vitelline glands : Either compact mass or small scattered follicles open in ootype.  Class : Cestoda (Tapeworms) Order Cyclophyllidae Morphology Cestodes are classified according to habitat into :- I. Intestinal Cestodes (Adult in the small intestine of man, Man is the D.H) 1. Taenia saginata 3. Hymenolepis nana II. Tissue Cestodes (Larvae in the tissues of man, Man is the I.H). 2. Hydatid cyst (larva of Echinococus granulosus or E. multilocularis) → Hydatidosis. Faculty of Medicine Microbial World Ass. Prof :Raghda Hussein Date : 9\2\2025  Learning Objective Definitions ❑Member of microbial world ❑Types of cells ❑Difference between Prokaryotic and Eukaryotic cells ❑Classification of bacteria  Definitions and Members ❑Microbiology is the scientific study of microorganisms. ❑Microorganisms are those organisms that are too small to see with the naked eye Members of microbial world  Types of cells Prokaryotic and Eukaryotic  Types of cells Prokaryotic and Eukaryotic Differences between Eukaryotic and prokaryotic cells Differences between Eukaryotic and prokaryotic cells  Classification of Bacteria According to 1. Shape : cocci ,bacilli ,vibirio ,…… 2. Ability to form spore 3. Source of nutrition 4. Gram stain : Gram +ve Violet in color and Gram –ve : Pink in color 5. Energy production : aerobe and anaerobe 6. Pathogenicity 7. Genotypic classification  Morphological Classification of Bacteria 1. Filamentous 2. Gram +ve cocci 3. Gram –ve cocci 4. Gram +ve bacilli 5. Gram –ve bacilli Morphological Classification of Bacteria Pathogenicity Classification of Bacteria  Genotypic Classification of Bacteria (Higher classification) 1. PCR 2. 16s Ribosomal RNA analysis 3. Plasmid fingerprint 4. Nucleic acid sequence analysis Field of Medicine Bacterial Cell Structure Date: 3 / 05 / 2023  Bacterial Cell Structure From outside to inside: 1-External structure: ✓Capsule. ✓- Flagella. ✓- Pili. 2-Cell envelope: ✓Cell wall ✓-Cytoplasmic membrane 3-Internal structures ✓-Cytoplasm. ✓-Nucleoid. ✓-Plasmid. ✓ -Mesosomes. ✓-Ribosomes. ✓ -Inclusion granules. 4- Endospore According to essentiality: Essential components Non essential components cell wall capsule cytoplasmic membrane flagella nucleoid pili mesosomes spores ribosomes plasmid  Cell Envelope: Cell Wall A cell wall is a layer located outside the cell membrane The major component of the bacterial cell wall is peptidoglycan or murein. This rigid structure of peptidoglycan, specific only to prokaryotes  Cell wall of GM+ve and GM –ve bacteria Gram-positive bacteria: Gram-negative bacteria: have a relatively thin cell wall consisting of: possess a thick cell wall a few layers of peptidoglycan containing many layers of peptidoglycan and surrounded by a second lipid membrane containing lipopolysaccharides and teichoic acids. lipoproteins. lipopolysaccharide: any of a large class of Teichoic acids are linear polymers of polyglycerol lipids conjugated with polysaccharides The lipopolysaccharide component acts as a or polyribitol substituted with phosphates and a virulence factor and causes disease in animals few amino acids and sugars. endotoxin: Any toxin secreted by a microorganism and released into the surrounding environment only when it dies.  Function of cell wall (A+3D+3P) 1. Responsible for the antigenicity of bacteria due to the presence of teichoic acid and lipopolysaccharides. 2. Determine the shape of the cell in its coccal, bacillary, filamentous or spiral form. 3. Determines the staining reaction of Gram stain due to the difference in its composition (Peptide cross links) between bacterial species.  Function of cell wall (A+3D+3P) 4-Plays an important role in cell division. 5-Protect the week cytoplasmic membrane by Providing structural support 6-Osmotic protection: protect the cell from bursting in hypotonic solution. 7-Protects the bacteria against the action of antibodies, antibiotics, and lysozyme by the lipopolysaccharide layer. Cell-Wall-Deficient Bacteria  Cell Membrane Proteins and phospholipids make up most of the membrane structure. proteins are found around the holes and help move molecules in and out of the cell. Osmotic sensitive  Function of CM 1. Selective permeability: maintain a constant environment within interior of the cell; it acts as permeability barrier and this permeability is also selective. It contains enzymes (permeases) that are involved in selective and active transport of nutrients into the cell and waste products out of it. 2 Plays an important role in cell division. 3 Respiration: it contains cytochrome generation of energy. enzyme responsible for respiration and  Function of CM 4Excretion of hydrolytic exoenzymes: Those digest large food molecules to subunits small enough to penetrate the cytoplasmic membrane. 5 -Secretion of exotoxins. 6Chemotactic systems: attractants and repellents bind to specific receptors in the bacterial membrane 7 -Site of biosynthesis of DNA ,Cell wall polymer  Mesosome: They develop by complex invagination of the cytoplasmic membrane into the cytoplasm; sometimes in relation to the nuclear body. Function: Play a role in cell division. They increase the surface area of the cytoplasmic membrane thus increasing the efficiency of permeability and active transport. It is the site for respiratory enzymes.  Capsule It is layer that lies outside the cell envelope. It usually consists of polysaccharides but can be composed of other materials such as glycoprotein, polypeptide D-glutamic acid in B. anthracis, and peptidoglycan and muramic acid found in E.coli bacterial capsule. Difficult to stain the capsule appears as a ring, or halo, around the cell  Function: 1. The capsule is considered a virulence factor because it enhances the ability of bacteria to cause disease (e.g. prevents phagocytosis). (Antiphagocytic) 2. Capsules also contain water which protects the bacteria against desiccation. 3. Capsules also help cells adhere to surfaces. 4. It protects the cell wall of bacteria against attack by various kinds of antibacterial agents e.g. bacteriophages, complement, lytic enzymes 5-Use in vaccination: used H.influenzae type b S. pneumoniae, and N.meningitidids  Appendage Flagella Pili Definition filamentous appendages Hair like filaments Site originates in the bacterial extend from the cell surface. protoplasm and is extruded through the cell wall. CCC long thin filament about 0.02um shorter and thinner than flagella thick Found in Motile bacteria non-motile and motile strains of Gram negative bacteria. Structure protein called flagellin. Formed of a protein called pilin It is antigenic  Flagella Pili types Ordinary - sex arrangement Monotrichous - Amphitrichous Lophotrichate -peritrichate function organ of motility in motile bacteria. Ordinary Fimbriae ( virulence factor). They move the bacteria towards mediate firm adherence of bacteria to nutrients and other attractants. specific receptors on human cell surface which is a necessary step in initiation of It is antigenic (H or flagellar antigen) infection for some organisms which helps in typing and identification of certain species of Sex pili bacteria e.g. serotyping of salmonella. 1Mediate attachment of two bacteria and transfer of DNA during conjugation. 2 They also act as receptor sites for certain bacteriophages.  3-Internal structures Cytoplasm: a viscous watery solution, or soft gel, containing ❑ -Nucleoid; Chromosomal DNA ❑ -Plasmid: Extrachromosomal DNA ❑ -Ribosomes: numerous small granules ❑ -Inclusion granules: Storage granules (Food granules).  Bacterial chromosome A single double stranded deoxyribonucleic acid (DNA) molecule about 1mm long, circular, supercoiled. not bounded to proteins. Has no outer nuclear membrane separating it from the cytoplasm and have no nucleolus. carries the genetic materials (determinants) that control the bacterial properties and behavior (contains about 2000 genes duplicated prior to cell division and each daughter cell will contain an identical copy of the chromosome  Plasmid 1. Are extrachromosomal double stranded circular DNA molecules smaller than the chromosome 2. Dispensable i.e. not essential. 3. Autonomous i.e. they multiply independent of the host cell. 4. Transmissible :Can be transferred to other bacteria by conjugation, transformation, or transduction. 5. Used as Vectors for cloning DNA (i.e. implanting certain genes) in yeast and bacteria.  Function Carry certain genetic information: -antibiotic resistance (R-plasmid). -Virulence: e.g. toxin production, invasiveness, adhesion by pili. -bacteriocins (Col factor plasmid). -sex pili (fertility F plasmid). - Antibiotic production. - Resistance to toxic metals  Ribosomes small granules 20nm in diameter. composed of 60 % RNA molecules % proteins 40%. They have a sedimentation constant of 70 S, being composed of a 30 S and 50 S subunits. The two subunits separate except in protein synthesis they aggregate to form polyribosome 70 S. They function in protein synthesis.  Inclusion granules These are not permanent or essential structures, which may be absent under certain conditions of growth. They are serves are storage areas for nutrient. They consist of volutin (polyphosphate, lipid, glycogen, starch or sulfur) e.g. volutin granules of Corynebacterium diphtheria.  Spore They are highly resistant resting forms of some Gram positive bacteria e.g. Bacillus and Clostridium. They are formed on exposure to unfavorable conditions e.g. depletion of nutrients, heat, dryness. The spore has no metabolic activity and remain dormant for years. Upon exposure to water and appropriate nutrients germination to vegetative form occurs. Spores are much more resistant than the vegetative forms to injurious chemical and physical influences, including exposure to disinfectants, drying and heating Why? The impermeability of their cortex and outer coat. Their high content of calcium and dipicolinic acid. Their low content of water. Their very low metabolic and enzymatic activity. Spore structure and position Spores appear as empty space by Gram stain but stained by special stain