Pharmaceutical Microbiology & Parasitology PHC412 PDF

PHARMACEUTICAL MICROBIOLOGY & PARASITOLOGY PHC412 The Gram-Positive Baciilli of Medical Importance  LEARNING OUTCOME 1 to understand and explain the morphology and pathogenesis of pathogenic bacteria to evaluate the consequences of infection, 2 treatment and control of s...

PHARMACEUTICAL MICROBIOLOGY & PARASITOLOGY PHC412 The Gram-Positive Baciilli of Medical Importance  LEARNING OUTCOME 1 to understand and explain the morphology and pathogenesis of pathogenic bacteria to evaluate the consequences of infection, 2 treatment and control of selected pathogenic bacteria  The Gram-Positive Bacilli 3. Gram-Positive Irregular Non-Spore- 2. Gram-Positive Forming Bacilli Regular Non-Spore- Forming Bacili 4. Mycobacteria: Acid-Fast Bacilli 1. Gram-Positive Spore-Forming 5. Actinomycetes : Bacilli Filamentous Bacilli Gram-Positive Bacilli 1. Endospore-formers i. Genus Bacillus ii. Genus Clostridium  General Characteristics of the Genus Bacillus 2 species of medical imp i. Bacillus Primary habitat is soil anthracis ii. Bacillus cereus Aerobic and catalase positive Mostly saprobic Gram-positive, endospore- forming, motile Source of antibiotics rods Versatile in degrading complex macromolecules  Bacillus anthracis Central spores that develop under all conditions except Spore in the living body Vegetative cell Virulence factors – Large, block- polypeptide capsule shaped rods and exotoxins 3 types of anthrax: 1. Cutaneous – spores enter through skin, black sore- eschar; least dangerous 2. Pulmonary –inhalation of spores 3. Gastrointestinal – ingested spores  Control and Treatment Treated with penicillin, tetracycline, or ciprofloxacin Vaccines Live spores and toxoid to protect livestock Purified toxoid; for high risk occupations and military personnel; toxoid 6 inoculations over 1.5 years; annual boosters  Bacillus cereus Common airborne and dust borne; usual methods of disinfection and antisepsis are ineffective Grows in foods, spores survive cooking and reheating Ingestion of toxin-containing food causes nausea, vomiting, abdominal cramps, and diarrhea; 24-hour duration No treatment available Increasingly reported in immunosuppressed  The Genus Clostridium 2. Anaerobicand 6. Synthesize organic acids, catalase negative alcohols and exotoxins 3. 120 species 5.Cause wound infections, tissue infections, and food 1. Gram-positive, intoxications spore-forming rods 4. Oval or spherical spores produced only under anaerobic conditions  Gas Gangrene Clostridium perfringens most frequent clostridia involved in soft tissue and wound infections – myonecrosis Spores found in soil, human skin, intestine, and vagina Predisposing factors – surgical incisions, compound fractures, diabetic ulcers, septic abortions, puncture wounds, gunshot wounds  Virulence Factors Virulence factors Toxins Alpha toxin – causes RBC rupture, edema, and tissue destruction Collagenase Hyaluronidase DNase  Pathology Not highly invasive; requires damaged and dead tissue and anaerobic conditions Conditions stimulate spore germination, vegetative growth and release of exotoxins, and other virulence factors Fermentation of muscle carbohydrates results in the formation of gas and further tissue destruction Treatment and Prevention Immediate cleansing of dirty wounds, deep wounds, compound fractures, and infected incisions Debridement of disease tissue Large doses of cephalosporin or penicillin Hyperbaric oxygen therapy No vaccines available  Clostridium tetanii is a common soil bacterium and the causative agent of tetanus. Vegetative cells of C. tetani are usually rod-shaped and up to.5 μm long, but they become enlarged and tennis racket- or drumstick-shaped when forming spores. spores are extremely hardy and can be found globally in soil or in the gastrointestinal tract of animals. produce a potent toxin, tetanospasmin, can be prevented with tetanus toxoid vaccines, which are often administered to children worldwide.  Pathology Spores usually enter through accidental puncture wounds, burns, umbilical stumps, frostbite, and crushed body parts Anaerobic environment is required for vegetative cells to grow and release toxin Tetanospasmin Tetanospasmin Tetanospasmin  Pathology Tetanospasmin – neurotoxin causes paralysis by binding to motor nerve endings; blocking the release of neurotransmitter for muscular contraction inhibition; muscles contract uncontrollably Death most often due to paralysis of respiratory muscles  Treatment and Prevention Treatment aimed at deterring degree of Neonatal tetanus toxemia and infection and maintaining homeostasis Antitoxin therapy with human tetanus immune globulin; inactivates circulating toxin but does not counteract that which is already bound Control infection with penicillin or tetracycline; and muscle relaxants Vaccine available; booster needed every 10 years  Clostridium difficile-Associated Disease (CDAD) Normal resident of colon, in low numbers Causes antibiotic-associated colitis Relatively non-invasive; treatment with broad-spectrum antibiotics kills the other bacteria, allowing C. difficile to overgrow Produces enterotoxins that damage intestines Major cause of diarrhea in hospitals Increasingly common in community-acquired diarrhea  Treatment and Prevention Mild uncomplicated cases respond to fluid and electrolyte replacement and withdrawal of antimicrobials Severe infections treated with oral vancomycin or metronidazole and replacement cultures Increased precautions to prevent spread  Clostridial Food Poisoning Clostridium botulinum – rare but severe intoxication usually from home canned food Clostridium perfringens – mild intestinal illness; second most common form of food poisoning worldwide  Botulinum Food Poisoning Pathogenesis Spores are present on food when Botulism – intoxication gathered and processed associated with inadequate food preservation If reliable temperature and pressure are not achieved air will be evacuated but spores will remain Clostridium botulinum – spore-forming anaerobe; Anaerobic conditions favor spore commonly inhabits soil and germination and vegetative growth water Potent toxin, botulin, is released  Motor neuron end plate Pathogenesis Muscle cell Muscle cell membrane membrane Botulin toxin is carried to neuromuscular junctions and blocks the release of acetylcholine, necessary for Vacuole muscle contraction to occur Double or blurred vision, difficulty swallowing, neuromuscular symptoms Presynaptic membrane  Infant and Wound Botulism Treatment and Prevention Infant botulism – caused by Determine presence of toxin in ingested spores that germinate food, intestinal contents or feces and release toxin; flaccid Administer antitoxin; cardiac and paralysis respiratory support Infectious botulism treated with Wound botulism – spores enter penicillin wound and cause food Practice proper methods of poisoning symptoms preserving and handling canned foods; addition of preservatives  Clostridial Gastroenteritis Clostrium perfringens Spores contaminate food that has not been cooked thoroughly enough to destroy spores Spores germinate and multiply (especially if unrefrigerated) When consumed, toxin is produced in the intestine; acts on epithelial cells, acute abdominal pain, diarrhea, and nausea Rapid recovery  Differential Diagnosis of Clostridial Species Diagnosis depends on the microbial load, persistance of isolate on resampling and condition of the patient Laboratory differentiation relies on testing morphological and cultural characteristics, exoenzymes,carbohydrate fermentation, reaction in milk and toxin production and pathogenicity Other method : gas chromatography, ELISA, antitoxin neutralization test and PCR analysis Spore-Forming Pathogens  The Gram-Positive Bacilli 2. Gram-Positive 3. Gram-Positive Regular Non-Spore- Irregular Non-Spore- Forming Bacili Forming Bacilli 4. Mycobacteria: Acid-Fast Bacilli 1. Gram-Positive Spore-Forming 5. Actinomycetes : Bacilli Filamentous Bacilli  2. Non-endospore- formers i. Listeria monocytogenes ii. Erysipelothrix rhusiopathiae  Listeria monocytogenes Non-spore-forming gram-positive Ranging from coccobacilli to long filaments 1-4 flagella and lack of capsules Resistant to cold, heat, salt, pH extremes, and bile Virulence attributed to ability to replicate in the cytoplasm of cells after inducing phagocytosis; avoids humoral immune system  Erysipelothrix rhusiopathiae Gram-positive rod widely distributed in animals and the environment Primary reservoir – tonsils of healthy pigs Enters through skin abrasion, multiplies to produce erysipeloid, dark red lesions Penicillin or erythromycin and vaccine for pigs  3. Irregular None- Spore i. Corynebacterium ii. The Genus Propionibacterium  Corynebacterium diptheriae Gram-positive irregular bacilli Epidemiology Pathology Reservoir of healthy carriers; 2 stages of disease: potential for diphtheria is 1.Local infection – upper respiratory tract always present inflammation (primary infection) Most cases occur in non- -Sore throat, nausea, vomiting, swollen immunized children living in lymph nodes; pseudomembrane crowded, unsanitary conditions formation can cause asphyxiation Acquired via respiratory Cutaneous (secondary infection) droplets from carriers or 2. Diptherotoxin production and toxemia actively infected individuals Target organs – primarily heart and nerves Diagnostic Methods Treatment and Prevention Pseudomembrane and Antitoxin swelling indicative Penicillin or erythromycin Stains Prevented by toxoid Conditions, history vaccine series and Serological assay boosters  Genus Propionibacterium Propionibacterium acnes most common Gram-positive rods Aerotolerant or anaerobic Nontoxigenic Common resident of pilosebaceous glands Causes acne  Gram-positive irregular bacilli 4. Mycobacteria : Acid-fast staining Acid-Fast Bacilli Strict aerobes i. Mycobacterium Produce catalase tuberculosis Possess mycolic acids and ii. Mycobacterium leprae a unique type of iii. Nontuberculous peptidoglycan Mycobacteria (NTM) Do not form capsules, flagella, or spores Grow slowly  Mycobacterium tuberculosis Tubercle bacillus Produces no exotoxins or enzymes that contribute to infectiousness Virulence factors – contain complex waxes and cord factor that prevent destruction by lysosomes or macrophages  Course of Infection and Disease Epidemiology of Tuberculosis Predisposing factors include 5% to 10% of infected people inadequate nutrition, debilitation of develop clinical disease the immune system, poor access to medical care, lung damage, and Untreated, the disease genetics progresses slowly; majority of TB cases contained in lungs Estimate 1/3rd of world population and 15 million in U.S. carry tubercle Clinical tuberculosis divided bacillus; highest rate in U.S. into: occurring in recent immigrants Primary tuberculosis Secondary tuberculosis Bacillus very resistant; transmitted (reactivation or reinfection) by airborne respiratory droplets Disseminated (extrapulmonary) tuberculosis  Primary TB Tubercle - granulomas consisting of a Multinucleate central core containing bacilli surrounded Epithelioid cells giant cell by WBCs ICenter of tubercle breaks down into necrotic caseous lesions, they gradually heal by calcification Caseous necrosis (tubercle bacilli at center) Granuloma (lymphocytes) Latent and Recurrent Tuberculosis Extrapulmonary Tuberculosis https://www.youtube.com/watch?v=202hkf43HXQ Clinical Methods of Detecting Tuberculosis 1.Tuberculin or immunologic testing 2. Radiography (X-rays) 3. Direct identification of acid-fast bacilli (AFB) in sputum or some other specimen and 4. Cultural isolation and identification https://malaysia.video.search.yahoo.com/search/video;_ylt=AwrKCx21Imlj4_YGx7LjPwx.;_ylu=Y29sbwNzZzMEcG9zAz EEdnRpZAMEc2VjA3BpdnM-?p=Mantoux+test&fr2=piv-web&type=E210MY0G0&fr=mcafee- malaysia#id=19&vid=a5f6a7d381740ece4f46ba963ae2e508&action=view Epiderms Dermis Injection of PPD Small bleb develops (a) 5–9 mm 10–14 mm 15 mm Positive if person Positive if person Positive if person is in category 3 (b) is in category 1 is in category 2  Management and Prevention of TB 6-24 months of at least 2 drugs from a list of 11 One pill regimen called Rifater (isoniazid, rifampin, pyrazinamide) Vaccine based on attenuated bacilli Calmet-Guerin strain of M. bovis used in other countries  Mycobacterium leprae : The Leprosy Bacillus Hansen’s bacillus/Hansen’s Disease Strict parasite – has not been grown on artificial media or tissue culture Slowest growing of all species Multiplies within host cells in large packets called globi Causes leprosy, a chronic disease that begins in the skin and mucous membranes and progresses into nerves  Course of Infection and Disease Macrophages phagocytize the bacilli, but a weakened macrophage or slow T cell response may not kill bacillus Incubation from 2-5 years; if untreated, bacilli grow slowly in the skin macrophages and Schwann cells of peripheral nerves 2 forms possible: Tuberculoid Lepromatous  Diagnosing Leprosy Combination of symptomology, microscopic examination of lesions, and patient history Numbness in hands and feet, loss of heat and cold sensitivity, muscle weakness, thickened earlobes, chronic stuffy nose Detection of acid-fast bacilli in skin lesions, nasal discharges, and tissue samples  Treatment and Prevention Treatment by long-term combined therapy rifampin and dapsone Prevention requires constant surveillance of high-risk populations WHO sponsoring a trial vaccine  Infections by Non-Tuberculosis Mycobacteria (NTM) M. avium complex – third most common cause of death in AIDS patients M. kansaii – pulmonary infections in adult white males with emphysema or bronchitis M. marinum – water inhabitant; lesions develop after scraping on swimming pool concrete M. scrofulaceum – infects cervical lymph nodes M. paratuberculosis – raw cow’s milk; recovered from 65% of individuals diagnosed with Crohn’s disease 5. Actinomycetes; Filamentous Bacilli i. Actinomycosis ii. Nocardia  Actinomycetes: Filamentous Bacilli Genera Actinomyces & Nocardia are nonmotile filamentous bacteria related to mycobacteria that may cause a chronic infection of skin and soft tissues Actinomyces israelii responsible for diseases of the oral cavity, thoracic or intestines – actinomycoses Nocardia brasiliensis causes pulmonary disease similar to TB THANK YOU https://www.youtube.com/watch?v=202hkf43HXQ