Microbiology and Parasitology

OPTOMETRY · SEMESTER 2 Introduction To Microbiology Microbiology and Parasitology START READING NOTES Contents of This Topic Introduction to microbiology Definition of terms Definitions contin……… Koch's postulates Koch’s Postulates Significance and Limitations Limitations: Questions Introduction to microbiology Concepts of microbiology Definition of terms Microbiology Definition: The study of microscopic organisms, which include bacteria, viruses, fungi, protozoa, and algae. Scope: It covers their structure, function, classification, reproduction, and how they interact with humans, animals, plants, and the environment Definitions contin……… Mycology Definition: A branch of microbiology that deals specifically with fungi. Includes: Yeasts, molds, and mushrooms. Importance: Some fungi are beneficial (e.g., penicillin-producing Penicillium). Others can cause diseases (e.g., Candida albicans causing yeast infections). Definitions contin……… Normal Flora Definition: Microorganisms (mostly bacteria, but also fungi and viruses) that naturally live on or inside the human body without causing disease. Role: Help in digestion. Protect against harmful microbes. Support immune function Definitions contin……… Pathogens Definition: Microorganisms that cause disease. Types: Bacteria, viruses, fungi, and parasites. Examples: Mycobacterium tuberculosis (causes tuberculosis) Influenza virus (causes flu) Plasmodium species (cause malaria) Koch's postulates Heinrich Hermann Robert Koch (1843–1910) was a German physician and pioneering microbiologist. He is considered one of the founding figures of modern bacteriology. Developed laboratory techniques such as: Solid culture media (using agar) Staining methods for bacteria Koch’s Postulates Formulated in the 1880s, Koch’s postulates are a set of four criteria designed to establish a causal relationship between a microorganism and a specific disease. The Four Postulates: Presence: The microorganism must be found in all organisms suffering from the disease, but not in healthy individuals. Isolation: The microorganism must be isolated from a diseased organism and grown in pure culture. Causation: The cultured microorganism should cause disease when introduced into a healthy organism. Re-isolation: The microorganism must be re-isolated from the experimentally infected host and identified as being identical to the original specific causative agent Significance and Limitations Importance: Provided the first scientific method to link specific microbes to specific diseases. Revolutionized the diagnosis and study of infectious diseases. Laid the groundwork for the germ theory of disease. Limitations: Not all pathogens can be cultured in the lab (e.g., viruses require host cells, M.leprae and T.Pallidum bacteria). Some diseases are caused by multiple organisms or by microbial imbalances. Asymptomatic carriers can harbor pathogens without showing disease symptoms. Modern microbiology has expanded on Koch’s ideas using molecular techniques and criteria like the Bradford Hill criteria for causation Questions Explain the Koch’s postulates Write down two limitations of Koch’s postulates What is a bacteria ? Define a pathogen , agent, vector and a host ← PREVIOUS TOPICNEXT TOPIC →VIEW MODULE NOTESVIEW SEMESTER NOTESALL OPTOMETRY NOTES Need These Notes as PDF? Request a formatted copy for offline study, printing or revision. GET PDF NOTES ON WHATSAPP

OPTOMETRY · SEMESTER 2 Protozoa 2 Microbiology and Parasitology START READING NOTES Contents of This Topic Learning Objectives List Protozoa of medical importance Cryptosporidium parvum Mode of transmission of protozoa of medial importance Characteristics of Cryptosporidium Parvum Life Cycle of Cryptosporidium Parvum Inside the cells the sporozoites develop into trophozoites , the feeding stage Life Cycle of Cryptosporidium Parvum cont.. Disease caused by cryptosporidium parvum Diagnosis Characteristics of Isospora Belli Medical Importance of Isospora Belli Specimens collected to diagnose protozoa of medical importance Overview of Trichomonas Vaginalis Characteristics of Trichomonas Vaginalis •It is actively phagocytic Morphological Features of Trichomonas Trophozoites Mode of Transmission Life Cycle The parasite does not appear to have a cyst form, and does not survive well in the external environment. Transmission can occur from female to male, male to female, or female to female partner Medical Importance of Trichomonas Vaginalis Laboratory diagnosis Laboratory technique Drugs of choice References Cook, G. (2000). Manson’s Tropical Diseases (22nd ed.). London: WB Saunders Company Ltd. PROTOZOA OF MEDICAL IMPORTANCE Learning Objectives By the end of this session, students are expected to be able to: Describe general characteristics of Protozoa List Protozoa of medical importance Explain mode of transmission of protozoa of medial importance Describe life cycle of Protozoa of medical importance List specimens collected to diagnose protozoa of medical importance List drugs of choice to treat protozoa of medical importance List Protozoa of medical importance Entamoeba histolytica Entamoeba coli Giardia lamblia Trichomonas vaginalis Trichomonas hominis Balantidium coli Cryptosporidium parvum Isospora belli Trypanasomes Plasmodium spp Leishmania Toxoplasma spp List Protozoa of medical importance Mode of transmission of protozoa of medial importance Oral-anal sexual cotanct Ingestion of contaminated food and drinks Blood transfusion Congenital transmission Vector-borne bite Sexual contact Penetration Cryptosporidium parvum Cryptosporidium parvum: Is a tiny coccidian parasite that causes outbreaks of diarrhoea (cryptosporidiosis ) It is one of several species that cause cryptosporidiosis, a parasitic disease of the mammalian intestinal tract. Cryptosporidium is a protozoan pathogen of the Phylum Apicomplexa Characteristics of Cryptosporidium Parvum The sporozoite measures 2-6 μm diameter. Cryptosporidium is capable of completing its life cycle within a single host, resulting in microbial cyst stages (oocyst). Oocysts are rounded and measure 4.2 to 5.4 μm in diameter. Oocysts are excreted in feces and are capable of transmission to a new host. Sporozoites are sometimes visible inside the oocysts, In modified acid-fast stain oocysts appear as bright pink to red organisms containing some dark granules and usually have a central clear area. Morphological Features of Cryptosporidium Parvum Oocyst Life Cycle of Cryptosporidium Parvum The life cycle of Cryptosporidium parvum consists of an asexual stage and a sexual stage The life cycle begins with oocysts Oocysts are infective at the time of excretion The ingested oocysts excysts when reaches the small intestine release four (4) sporozoites The sporozoites invade epithelial cells of small intestine and become intracellular, settling in the cell surface called the parasitopharous vacuole . Inside the cells the sporozoites develop into trophozoites , the feeding stage Trophozoites undergo merogony (asexual division ) forming meronts containing merozoites And merozoites are released to infect the new cells Some merozoites develop into microgametocytes and Macrogametocytes Life Cycle of Cryptosporidium Parvum cont.. Life Cycle of Cryptosporidium Parvum cont.. These initiate the sexual life cycle after microgametes to fertilize the macrogametocytes forming a zygote later on, the zygote develop to form oocyst Thick- walled oocysts are passed in stool and can infect others Thin -walled oocyst can cause auto infection within the same host Life Cycle of Cryptosporidium Parvum Disease caused by cryptosporidium parvum Cryptosporidium parvum causes cryptosporidiosis characterized by unremitting, profuse diarrhea This leads to malabsorption , dehydration, chronic diarrhoea , electrolyte imbalance ,severe weight loss and wasting. In immunocompetent the disease is always self limiting but severe in immunosuppressed patient such as HIV infected people Diagnosis Specimen o Stool o Serum Technique o Microscopy Wet mount Modified ZN stain o Serological tests Characteristics of Isospora Belli It is opportunistic parasite associated with AIDS The oocyst is elongated-ellipsoid constricted at one end asymmetrical at the other end (rugby ball shape) The wall is smooth, colourless and refractive Its size measures about 28 x 14μm The sporocyst and sporozoite are subspheroid to ellipsoid measuring 14 x 10 μm in size Medical Importance of Isospora Belli Isospora belli causes isosporiasis o Diarrhoea (usually self-limiting) in immunocompetent patients o Chronic diarrhoea in the immunocompromised patients like in HIV&AIDS which is characterized with body wasting , electrolyte imbalance , profuse diarrhoea Diagnosis Specimen o Stool o Serum Technique o Microscopy Wet mount Modified ZN stain o Serological tests ELISA Specimens collected to diagnose protozoa of medical importance Fresh stools Rectal scrapings Liver aspirate Blood Mucosal scraping (from the sigmoid colon) Bone marrow lymph nodes fluid, Liver and spleen aspirates. Urine High Vaginal Smear Overview of Trichomonas Vaginalis The Trichomonas vaginalis are flagellate protozoa (mastigophora) that are characterized by having an undulating membrane and a number of flagella. They are adapted to living in the genital urinary tract of man. Trichomonas vaginalis is responsible for causing a sexually transmitted disease called Trichomoniasis Characteristics of Trichomonas Vaginalis Trichomonas vaginalis is a colourless pear-shaped, with a short undulating membrane supported by a single flagellum and four anterior flagella It measures about 10 x 7μm, though its length may vary from 5 to 30μm and its width from 2 to 14μm The organism moves with a characteristic wobbling and rotating motion The nonpathogenic trichomonads, Trichomonas hominis and Trichomonas tenax, cannot readily be distinguished from Trichomonas vaginalis when alive •It is actively phagocytic Optimal growth occurs under moderately anaerobic conditions Reproduction is by binary fission Unlike many pathogenic protozoa don’t form cyst Morphological Features of Trichomonas Trophozoites A: Normal trophozoite B: Round form after division C: Common form seen in stained preparation Mode of Transmission Transmission is primarily by unprotected sexual intercourse Contaminated towels and examination instruments and materials Infants may be infected during birth (congenital ) Life Cycle of Trichomonas Vaginalis Life Cycle Trichomonas vaginalis resides in the

OPTOMETRY · SEMESTER 2 Additional Study Notes: Contact Lens Infection Prevention Microbiology and Parasitology Additional Study Notes — newly authored explanations and examples. These sections supplement the supplied course material. START READING NOTES Contents of This Topic Learning objectives Clarifications to the supplied RNA-virus lecture Connecting microbiology with practice Cleaning, disinfection and water Patient teaching and teach-back Symptoms requiring prompt assessment Learning objectives Relate lens hygiene to microbial keratitis and explain the difference between cleaning and disinfection. Clarifications to the supplied RNA-virus lecture The RNA-virus slides include hepatitis B in their examples. Hepatitis B virus is a partially double-stranded DNA virus; it should not be classified as an RNA virus. CDC describes transmission through parenteral or mucosal exposure to infected body fluids. Do not treat all hepatitis viruses as sharing one transmission route. Hepatitis A is predominantly transmitted by the faecal–oral route. The source lecture’s broad route lists mix different viruses and should be checked organism by organism rather than memorised as universal rules. Connecting microbiology with practice A contact lens and its storage case can carry microorganisms to the ocular surface. Corneal infection is clinically important because it can damage vision. CDC identifies microbial keratitis as a serious contact-lens-associated infection. Teaching should connect the organism, route of exposure, condition of the ocular surface and hygiene behaviour rather than treating organisms as isolated lists. Cleaning, disinfection and water Cleaning removes deposits and debris; disinfection reduces harmful microorganisms using the prescribed system. Follow the lens-care system instructions, including the required timing. Rinse and rub a reusable storage case with fresh appropriate solution, not water. Keep lenses away from water and remove them before swimming or showering. Do not use tap water as a storage or rinsing fluid. The CDC links contact lens water exposure with infection risk. Patient teaching and teach-back An original teaching activity: ask a learner to demonstrate the complete routine with a practice case, explaining each step. Then ask what they would do if the lens touched water or the eye became painful. This tests understanding more effectively than asking only whether instructions were understood. Discuss the prescribed replacement and wearing schedule with the eye-care professional. A fitting and appropriate instructions are necessary; contact lenses are not simply a spectacle prescription transferred to another material. Overnight wear carries infection risk. Symptoms requiring prompt assessment CDC lists eye pain, redness, light sensitivity, blurred vision and unusual watering or discharge among symptoms of bacterial keratitis. A contact-lens wearer with these symptoms should remove the lenses and contact an eye-care professional promptly; they should not continue wearing the lenses while waiting for the symptoms to disappear. Study References CDC: What causes contact lens-related eye infections CDC: Cleaning, disinfecting and storing contact lenses CDC: Keeping water away from contact lenses CDC: Contact lens types CDC: Bacterial keratitis CDC: Hepatitis B surveillance manual CDC: Hepatitis B Pink Book CDC: Clinical overview of hepatitis A External references checked 13 September 2026. Worked numerical examples and teaching activities are original. ← PREVIOUS TOPICVIEW MODULE NOTESVIEW SEMESTER NOTESALL OPTOMETRY NOTES Need These Notes as PDF? Request a formatted copy for offline study, printing or revision. GET PDF NOTES ON WHATSAPP

OPTOMETRY COURSE Microbiology and Parasitology — Optometry Notes Semester 2 · 13 topics. Source notes and Additional Study Notes are identified by their titles. Bacterial Cell Structure and Classification Normal Flora Gram negative bacteria session 4 Onchocerca volvulus DNA Virus Gram Positive Bacteria Introduction To Mycology Introduction To Parasitology 1 RNA Virus 5 Vector Of Medical Importance Para 08 Introduction To Microbiology Protozoa 2 Additional Study Notes: Contact Lens Infection Prevention SEMESTER NOTESALL OPTOMETRY NOTES Need These Notes as PDF? Request a formatted copy for offline study, printing or revision. GET PDF NOTES ON WHATSAPP