Week 6 GP- Microbiology Flashcards
What do antibiotics target (4) (3 I, 1 D)
- Inhibition of bacterial cell wall synthesis
- Interaction with the cell membrane
-Disruption of DNA and RNA sythesis
-Inhibition of cell metabolism e.g Folate synthesis
What is the difference between narrow and broad spectrum antibiotics (3) and the effects on microbes (2)
- Broad spectrum: Effective against prokaryotes which kill or inhibit wide range of Gram+ and Gram - bacteria
-Narrow spectrum: effective against Gram + or Gram - bacteria
- Limited spectrum: Effective against a single organism or disease
Effects on microbes:
-Cidal (killing) effect
- Static (inhibitory) effect
Beta-Lactams/cell wall inhibitors (1)
Penicillin (PCN)
- Blocks peptidoglycan cross-liking
- Only bactericidal calls if are actively synthesizing cell wall
- Resistance, inactivation by bacterial Beta lactamase (most common)
Penicillin that is resistant
PCN can be resistant to staphylococcal beta lactamase
Methicillin and Nacfcillin.
But then bacteria become resistant to MRSA (methicillin resistant staphylococcus aureus)
Discuss the advantages (5) and disadvantages (5) of microbiota
Advantages:
-Contributes to health
-Protective host defense by maintaining conditions such as pH
-Other organisms may not grow
-Serves nutruital functions by synthesizing K &B vitamins
- Competition for space
Disadvantages:
-Can produce disease if introduced to foreign locations
- They result in hospital acquired infections
-Immunocompromised host e.g AIDS
-Bacterial interference, competitions with microbiota and pathogens
- Clinical connection- Human microbiome + C difficile, clostridium difficile is a gram positive rod shaped bacteria that cause severe diarrhea after normal gut flora are killed by antibiotics
Factors that increase susceptibility to infections
- Age
- Defects in immune response acquried
- Pre exisiting medical disease (comorbidites)
-Immunosuppression, chemotherapy
-Malnutrition
-Transplantation
-Prosthetics
Define Pathogenic, Opportunistic, Exogenous, Endogenous
Pathogenic: Always causes a a disease e.g Rabies, Bacillus anthracis (anthrax), Shingles, Salmonella enterica (typhoid)
Opportunistic: can cause a diease only when host defense are compromised or changed locations e.g staphylococcus aureus
Exogenous: From external sources e.g influenza, Neisseria gonorrhoeae, escherichia coli, coccidioidies immitis
Endogenous: From the persons own microbial flora, spreads normally to sterile body sites (blood, brain, lungs, peritoneal cavity) e.g cystitis (Ecolie) or normal colonized sites (vagina, mouth, throat, GI tract and UT) e.g bacterial vaginosis
How do bacterial disease happen
Toxic efffects of bacterial products (e.g toxins ex, tetanospasmin)
- when bacteria invade normally sterile body tissue and fluids
-Expression of virulence factors that cause tissue damage, stimulating inflammation or both
In bacterial infections explain Exotoxin vs Endotoxin
Exotoxins are proteins produced inside pathogenic bacteria, most commonly gram positive bacteria e.g tetanus toxin C. tetani
Endotoxins: are a lipid A portions of LPS that are part of gram negative bacterial outer membrane e.g N.meningitidis
Process of infections- Viral
Rapid replications and destruction of the cell or long term chronic relationship with possible integration of the viral genetic information into the host genome
Acute, chronic and even cancer-promoting presentations.
What is the process of infection (3)
- Attachment and entry
- Interfere with host immune defenses
- Exit/ shed from the body
Explain the process of infection of Neisseria meningitis and Escherichia coli
Neisseria mengitits: causes pneumonia and meningitis.
Pathogenic, exogenois, exogenous, endotoxin (lipid A LPS), IgA protease
Escherichia Coli
Causes watery diarrhea, hemorrhagic colitis, hemolytic uremic syndrome (HUS)
Pathogenic, exogenous, shinga toxin (exotoxin), prevents protein synthesis and destroys red blood cells.
Explain the process of Influenza virus
- +ssRNA virus causing influenza, pathogenic, exogenous, hemagglutinin (H) spikes for attachment, neuroaminidase (N) spikes for release, antigenic shift and drift
Explain the process of Fungal infections (3)
- Superficial or cutaneous mycosis (hair, skin, nails), secrete enzymes that break down keratins
- Systemic mycosis- enteres via lungs and spread to other organs
-Opportunistic mycosis- overabundance of normal fungal flora
Process of infection of Parasites
- Some parasites establishing a permanent relationship with human and others going through a series of developmental stages in a progression of animal hosts
- Cell and tissue damage
- Interference with host defenses
Give 5 examples of symbionts and parasites
- Fleas, ticks, tapeworms, lice, leeches
Discuss the Antimicrobial drugs and modes of actions
Inhibits steps in cell wall(peptidoglycan) synthesis:
Beta lactams penicillin G, cephalothin,
Semisythetic penicillin (ampicillin, amoxicillin)
Glyocpeptides (Vancomycin)
Suicide inhibitor beta-lactamases, clavulanic acids, clavamox (clavulanic acid + amoxicillin)
Inhibit cell metabolism folate synthesis: Sulfonamides, “Sulfa drugs” trimethoprim
Inhibits translation (protein synthesis)
-Aminoglycosides (streptomycin) Macrolides (Erythromycin) Tetracyclines (Tetracycline)
Inhibits nucleic acid synthesis
- Quinolones (ciprofloxacin), Rifamycins
Damages cytoplasmic membranes Polypeptides (Bacitracin)
Discuss Fungi, Mycoses
Mycology is the study of Fungi (molds, yeasts and mushrooms)
All fungi are
-Eukaryotic (true nucleus, 80s ribosomes, mitochondria as are humans
complex carbohydrates cell walls- chitin, glucan and mannan
Ergosteriol, major membrane sterol
- Azoles antifungals inhibit synthesis of ergosterol
- Polyene antifungals binds more tightly to ergpsterol than cholestrol (amphotericin B, Nystatin)
Explain the 4 Fungi spore types
- Conidia
Asexual spores, formed off hyphae, common and airborne - Blastochonidia
Buds on yeast (asexual budding daughter yeast cells) - Arthroconidia
Asexual spores formed by a “joint” - Spherules
Spores inside the spherules in tissues
Describe the levels of penetration of Fungi
- Superficial mycoses
Are fungi growing on the surface of skin or hair - Cutaneous mycoses
Are in superficial layer of skin/nails/hair such as ringworm or athletes foot - Subcutaneous mycoses
Penertrates below the skin into muscles tissue, connective and bone tissue - Systemic mycoses / deep
Reaches internal ograns and disseminate through the body, often fatal.
What is the fugal morphology
Yeasts= single celled (round to oval) fungi
Pseufohyphase (candida albicans) sausage- like filaments with constrictions at each septum
Hyphase filamentous cellular units of molds and mushrooms
Nonseptate hyphae: No cross walls, broad hyphae with irregular width, broad angles of branching
Septate Hyphae: With cross walls (septum) width is farily regular (tube like)
Mat of hyphae= mycelium
What is Dimorphic fungi
Fungi able to convert from hyphal to yeast or yeast like forms
Thermally dimorphic
in the cold are the mold forms, coverts to yeast in the warm body.
Body Heat Changes Shape
Blastomyces, Histoplsama, Coccidioides, Sporothirx
Discuss Parasites types (3)
Protozoa: Entamoebida (amebas), Sporoza (sprozoans), Metamonda (flagellates), Ciliata (ciliates)
Helminths: Platyhelminthes (flatworms)- trematoda (flukes) Cestoda (tape worms)
Nematoda (round worms)
Arthropods: insecta (insects, ticks and mites)
Discuss Protozoa parasite
- Unicellular, life cycle consisting of trophozoite, motile, feeding, reproducing form surrounded by a flexible cell membrane,
Cyst nonmotile, nometabolsing nonreproducing form surrounded by a thick wall.
Reproduction: generally by simple binary fission (merogony) life cycle of sporozoans includes cycles of multiple fission alternating with a periods of sexual reproduction
Discuss parasites Helminths
- Multicellular,
lifecycle egg- larva- adult
A definitive host is one which the sezxual cycle occus or the adult is present.
The intermediate host is one which the asexula cycle occurs or larva is present
Discuss Parasites arthropods
-Have segmented bodies, paired with legs
-Well developed digestive and nervous syste,
-Sexes are separate
-All have a hard chitin covering as an exoskeleton
-Many arthropods feed on human blood and tissue fluids
E.g ticks, scabies, bedbugs, body lice
Explain the viral characteristics that contain DNA - 2 types with examples
Enveloped the membranous structure of the envelop can be maintained only in aqueous solutions, it is readily disrupted by drying, acidic conditions and detergents.
Examples: pox, herpes, hepadna
Naked capsid: The capsid is rigid structure able to withstand harsh environmental conditions
Examples: Polyoma, papilloma, adeno
Parvo SS
What is the function of protein coat “capsid”
Protein coat surrounding the nucleic acid.
Subunits: capsomers
Functions: Protection, mediate attachment, species and organ specifically, antigen
Explain the viral life cycle
- Recognition of the target cell
- Attachement
- Penetration
- Uncoating
- Macromolecular synthesis: Early mRNA and nonstructural protein synthesis genes for enzymes and nucleic acid- binding proteins, replication of genome, late mRNA and structural proteins synthesis, post translational modification of protein
- Assembly of virus
- Budding of enveloped viruses
- release of virus
Prokaryotes
- One circular chromosomes not in a membranes,
- No organelles, peptidoglycan cell wall
- Binary fission
- Bacteria
