Microbiology Lecture Notes PDF

B) Blackhead Mite (Demodex): o Tiny, elongated body o D. folliculorum :lives in human facial small hair follicles...

B) Blackhead Mite (Demodex): o Tiny, elongated body o D. folliculorum :lives in human facial small hair follicles o D. brevis :lives in pilosebaceous glands in eyelashes o Seldom cause much pathology :Demodicosis. Microbiology o Cylindrical dandruff at base of eyelashes are pathognomonic o Prevention: face cleansing ,exfoliating, & avoid oil-based makeup. o Treatment :permethrin cream or Sulphur ointment. Microbial ecology § Science of systematic study of inter-relationships which exist between living organisms & ecosystem (environment): § Environment components: 1) Biotic (living): plants, animals, & other as bacteria. 2) Abiotic (non-living) : water, soil, & atmosphere. § Symbiosis (symbiotic relationship): o Inter-species biological interaction. C) Dermatobia hominis (human bot fly): o Two dissimilar (usually 2 different spp) organisms (Symbionts) o Endemic in Central & South America. living together or in close association. o Female lay & attach eggs on other zoophilic blood-feeding porter vectors (mostly flies, or mosquitoes or ticks). o Blood-feeding insects transport eggs into human o Causes furuncular myiasis. Symbiosis o When porter vectors bite host, eggs hatch & released larvae 1) Neutralism: introduced into skin of human host through bite woundà Boil-like lesions. § Neither symbiont is affected by relationship. o Treatment: Extracted fly larvae (maggots). § Occupying same ecologic niche. 2) Commensalism § Beneficial to only one symbiont & of NO consequence to other. § Neither organism is physiologically dependent on the other. à Examples: A) Many MOs of indigenous microflora of humans o Microflora: space & nutreints o Human: none 3) Parasitism C) Medicinal Leeches § Beneficial to one (parasite) & detrimental (harmful) to other. o History: treatment of abscesses & wounds § Types: o Recently: treatment of venous congestion after plastic surgery. o Nonpathogenic: only dumb parasites kill their hosts o Aeromonas (GNB) normal flora in gut of leeches (digest blood) o Pathogenic: o Treatment by leeches wound Infections due to Aeromonas. o Wound infection prevented by prophylactic antibiotics § Trypanosoma gambiense: Causes african sleeping sickness 4) Mutualism § Beneficial to both symbionts :mutually beneficial. à Examples: A) Many MOs of indigenous intestinal normal microflora: D) Termites ( ‫)اﻟﻨﻤﻞ ﻻﺑﯿﺾ‬ o E. coli :vitamin K production. o Small insects ,eat but cannot digest wood. o Others : prevent pathogen Colonization. o Warm moist space & nutrients for intestinal protozoa o Protozoa break down large wood molecules into smaller cellulose molecules (easily absorbed) B) Wolbachia (Wolbachia pipientis): o Intracellular GNB, related to Rickettsia. E) Lichen o The most common reproductive parasite in the biosphere. o Colored patches grown on tree trunks & rocks. o Infect only ovaries and testes o Composed of: o Live in arthropods (insects, arachnids): § Not transmissible to humans & make them sterile. 1) Fungus (molds): hyphal cell wall’s chitin (protect algae from desiccation). o Live in Certain filarial nematodes: 2) Alga : photosynthesis (energy for both). 1) Onchocerca volvulus (river blindness) § Wolbachia requaired for survival of macrofilirae (adult worm) § Doxycycline: kills Wolbachia à kills macrofilirae (not microfilirae) 2) Dirofilaria immitis (Heartworm disease in dogs) Human Indigenous Microflora (Microbiota ,Normal Flora) 1) Resident: à Significance in Biocontrol (Sterile Insect Technique) § All microbes which reside on or within body. § Can be targeted to manage infections. § 10 times # of human body cells (10 trillion cells)= 100 trillion § Suppress mosquito burne diseases § Humans are actually only 10% “human” & 90% bacterial! § Sterility Mechanism: § 500-1000 different bacterial spp, o Lab-bred Wolbachia-infected mosquitoes eggsà sterile &. § Differ according to conditions of each anatomical site o Mosquitoes are released to mate with wild populations. § Body fluids (Blood, Lymph & CSF), & most internal tissues & o Infertile eggs that don't hatch, reducing mosquito populations over organs: sterile (Free of MOs). time (Wolbachia spreads maternally). § Destruction→ SUPERINFECTION. 2) Transient: Carriers § Microflora from external environment taking residence only temporary Carrier Type Description § Temporary because: Asymptomatic Carry & spread a pathogen without showing symptoms o Washing by bathing (Healthy) Incubatory Spread pathogens during the incubation period before o Flushing away by body excretions & secretions symptoms appear o Failure to survive in acidic or alkaline pH, Convalescent Transmit pathogen during recovery after symptoms subside o Killing by toxins of resident flora. Chronic Harbor & spread pathogens long-term. 1) Healthy asymptomatic carriers: Microflora of Skin § Nasal& skin: Staph aureus. § Mainly anaerobes in :deeper skin layers, hair follicles, sweat glands § Nasopharyngeal: § Most common bacteria: Disease Causative Microorganism o Staph (S epidermidis & other CONS), Diphtheria Corynebacterium diphtheriae o Non diptheria Corynebacterium (Diphtheroid) Whooping Cough Bordetella pertussis o Propionibacterium: causes Acne vulgaris. Meningitis Neisseria meningitidis o Most common fungus: C albicans. Pneumonia Streptococcus pneumoniae § Hand washing to decrease hospital acquired infection (HAI). § Hands: Klebsiella, Pseudomonas, Staphylococcus (hosbitals). § Burns, lacerations, wounds, & surgery→ skin Infs. 2) Incubatory carriers ,Convalescent carriers ,Chronic carriers: § EBV, Flu, Covid-19, Poliomyelitis, HBV, & HIV. Microflora of Ears & Eyes TB & C. difficile, Cholera & Chlamydia. § Outer ear & auditory canal: Flora similar to those of skin. § Salmonella typhi (Mary Mallon (chronic)/ Typhoid Mary) § Middle & inner ear: sterile. § Conjunctiva: Microflora of Oral Cavity (Mouth) o Despite tears’ mechanical flow, lysozyme , & other antimicrobial § Anaerobic (gum margins, crevices b/w teeth& tonsils) & Aerobic bacteria o Staph, Strep, Diphtheroid & Moraxella catarrhalis. § Decrease in Dental hygieneà Dental caries, gingivitis & more severe periodontal disease § Bacteria, yeasts, protozoa & viruses. à Bacteria: Microflora of RT o GPC: Staphs, Strep / GNC: Neisseria, Veillonella § Lower RT : Larynx, trachea, bronchi, bronchioles & lungs with effective o GPB: Corynebacterium, Lactobacillus, Actinomyces,Propioni.. defense mechanisms :Usually sterile. o GNB: Hemophilus,Fusobacterium,Porphyromonas, Prevotella, Bacteroide o Spirochetes: Treponema, & Borrelia. § Upper RT :Nose & throat (pharynx) with moist warm mucus membrane: à Most common= alpha-hemolytic strep (Strep viridans). 1) Harmless: Diphtheroids, Lactobacilli & Micrococci. à Streptococcus Mutans: 2) Opportunistic: Strep, Staph, Neisseria & Corynebacterium. o Most implicated in plaque formation , cavities & tooth decay o Growth is suppressed by catechins in Green Tea Microflora of GIT Reproductive Systems à Stomach (pH 1.5) has no flora except: § Sterile Regions: Generally sterile except for the vagina. § Helicobacter pylori : causes peptic ulcers § Vaginal Microflora (Composition by Life Stage): § In conditions like Achlorohydria or partial gastrectomy. o Puberty & Menopause: Alkaline pH à Diverse microflora à Small Intestine: o Childbearing Years: Acidic pH (4-5) à Dominated by Lactobacillus, producing lactic acid and inhibitory by-products. § Duodenum: Bile prevents bacterial growth. § Jejunum & Ileum: Staph, Lactobacillus , Streptobacillus § Oral Contraceptives and Vaginal pH: , Veillonella, Clostridium perfringens. o ↑ pH → ↓ Lactobacilli → Increased susceptibility to infections: à Colon: § Bacterial Vaginosis (BV): § Largest Microbial Diversity: 600 bacterial species o Gardnerella,Mobiluncus,Bacteroides,& anaerobic cocci o Watery non-inflammatory discharge lacking WBCs ) o Obligate Anaerobes: GPC + GNC + GPB + GNB o Facultative Anaerobes: GNC + GPB + GNB § Yeast Vaginitis: Overgrowth of Candida albicans. § Other Microorganisms: Fungi, protozoa, viruses. § Ecological Role: o Opportunistic: Can thrive in changing habitats. à Beneficial Role of microflora o Indicators: Water fecal contamination markers. 1) Vitamins Production by intestinal normal flora as: Urinary Tract B1 (Thiamine) B5 (pantothenic acid) B6 (pyridoxine) B7 (biotin) B12 (cyanocobalamin) Vit K,folic acid § Sterile Regions: Kidneys, ureters, and bladder. § Distal Urethra & External Meatus: Colonized by: § Fat soluble vitamins: K. o Bacteria: 2) Constant source of Ags stimulating immune system § GPC: Staphylococcus, Streptococcus, Enterococcus § GNC: Nonpathogenic Neisseria spp 3) Microbial Antagonism: § GPB: Diphtheroids § Prevention of opportunistic pathogens overgrowth & colonization § Enteric GNB, anaerobes, Mycoplasma, Mycobacteria by competing for nutrients & colonization sites o Other Microorganisms: Yeasts, viruses. § Production of bacteriocins. § Protection: Acidic urine (low pH) and mechanical flushing. Bacteriocins Antibiotics § Recurrent UTIs: Antibacterial proteins (peptides) Antibacterial chemical substance o Anatomical abnormalities: ureteric stricture Certain bacterial: E coli (colicin) Soil-living MOs: Bacteria & Fungi o Physiological abnormalities: reflux § Cranberry could be protective against UTI: bad taste Colistin is an antibiotic. During primary phase of growth As secondary metabolites à Common Urethritis Causes: More potent. Less potent o Chlamydia trachomatis, Narrower activity spectrum Wider activity spectrum o Neisseria gonorrhoeae (gonococcus), o Mycoplasma. Epidemiological bacterial typing For treating of bacterial Infection Probiotics Prebiotics § Biotherapeutic M.O (harmless bacteria or yeast) that improve host health. § Non-digestible food ingredients à Delivery: o Trans-galacto-oligosaccharide, fructo-oligosaccharide, A) Oral: o Lactulose, inulin, and beta-glucan § Common strains: § Stimulate beneficial gut bacteria growth. o Lactobacillus : yogurt o Bifidobacterium o Nonpathogenic Enterococcus, à Harmful Role of microflora: o Saccharomyces (yeast). ü Opportunistic potential pathogens in cases of: § Benefits: o Enhance gut flora diversity. 1) Change of anatomical site in immunocompetent: o Restore microbial balance by replacing pathogenic microbes. § Harmless intestinal E coli causes à serious infections in urinary o Reduce inflammation. bladder, blood stream, lungs, wounds. B) Nasal (Spray): § Also: Enterobacteriaceae, S aureus & Enterococcus § Streptococcus sanguinis: Treats otitis media (significant recovery) 2) Prolonged use of broad-spectrum antibiotics § Neisseria lactamica: § Reduction or elimination of certain resident indigenous microflora o Prevents meningitis by reducing N. meningitidis colonization § Superinfection: overgrowth of resistant opportunistic MOs: o Mechanism: microbial competition or innate immune response § Examples: Key trick to remember: A) Clostridium difficile in the colon: Think of FMT as “Good poop saving bad guts” and remember: C) Fecal Microbiota Transplantation (FMT):. C. diff, Colitis, Listeria, Cholera § Stool from healthy donors into a patient’s GI tract o Antibiotic-associated diarrhea (AAD): § Donor stool is screened, cleaned, and processed § Mild form § Procedure via: o Pseudomembranous colitis (PMC): o Colonoscopy (most common) or Enema or Capsules § life-threatening § Uses: o Treatment: § Recurrent C. difficile inf. (Twice as effective as antibiotics) B) Candida albicans § Ulcerative colitis (Inflammatory Bowel Disease). o Causes: candidiasis/moniliasis: o In the mouth: thrush o Prevention: o In the vagina: yeast vaginitis § Listeriosis: Reduces risk via suppression of pathogenic Clostridia. 3) Increased vaginal pH: overgrowth of C albicans → yeast vaginitis. § Cholera: by Lactococcus lactis lowers intestinal pH with 4) Immunocompromise due to diseased & chemotherapy lactic acid, inhibiting Vibrio cholerae. 5) Other: Burns, lacerations, wounds, & surgical procedures. Biofilms Synergism (mixed, or polymicrobial infections) § Complex microbial communities ( cooperative colonies). § ≥ 2 different microorganisms (MOs) in a synergistic relationship § Embedded in a hydrated extracellular polymeric substance (EPS) matrix. § Cause a disease that neither could cause alone. § Grow in Microcolonies: separated by water channels for nutrient supply 1) Serious acute necrotizing ulcerative gingivitis (ANUG) or Trench and waste removal. mouth, or Vincent’s angina: § Cooperative behavior: o Surfactant ,enzyme & Structural matrix components production. § Mixed normal oral flora; spirochetes (Borrelia vincentii)+ o Waste recycling by interdependent bacteria. anaerobes (Fusobacterium) + Prevotella & Actinomyces § Infection of gingiva, à oral mucosa, pharynx & tonsils § Swelling, necrosis, bleeding, & gangrenous tissue sloughing § Thick, hydrophobic layers limit antimicrobial penetration. (bad breath). § Electrically charged biofilms repel antimicrobials via electrostatic forces. § Risk factors: Poor hygiene, malnutrition, smoking, stress, § Deep bacteria devide very slowà resistance to penicillin. vitamin deficiency, immunosuppression, malocclusion. § Penicillinase from some bacteria protects the entire biofilm. § Treatment: tissue debridement 2) Ludwig’s angina: § Cinnamaldehyde (in cinnamon): active in disrupting of persistent biofilms § Mixed bacterial species of normal oral flora; Staph ,Strep & anaerobes (Peptostrep, Prevotella, Porphyromonas, Fusobacterium) § Acute, bilateral cellulitis in mouth (submandibular/sublingual). § Tongue swelling, dysphagia, erythema, mouth pain, fever, malaise, airway obstruction (life-threatening). § Abscess formation, septic shock, airway obstruction § Risk factors: Dental infections, poor hygiene, oral injuries, immunosuppression, dental extraction, lingual frenulum piercing. § Treatment: tissue debridement à High incidence in: 3) Bacterial vaginosis:Mixed bacterial species of normal vaginal flora o Catheters, endotracheal tubes, prosthetics (valves, joints). o Surgical wounds, burns, and prolonged hospital stays. Agricultural Microbiology § Farm Animal Pathogens: bacteria, viruses, fungi, protozoa,& helminths. à Biofilm-Related Diseases: § Impact: Zoonotic diseases & Economic losses. o Periodontal disease, otitis media, endocarditis, o Arthritis & cystic fibrosis (CF) o Kidney stones & prostate infections. Soil Pathogens 1) Clostridium spp.: Causes tetanus, botulism, and gas gangrene. 2) Bacillus anthracis: Causes anthrax. 3) Yeasts: Cryptococcus neoformans.