Med and Gen micro 2 Flashcards

Question

Properties of biofilms and habitat formation?

Answer 1

Localized gradients eg. pH provides habitat diversity Sorption for resource capture Enzyme retention for external digestion system Continuous regneration Tolerance makes it act as a fortress

Answer 2

Primary colonisers on the surfaces including teeth and soft tissues Secondary colonisers attach to primary colonisers Maturation of plaque - growth in situ and attachment and detachment to the existing biofilm Disease causation - pathogenic effects include the release of toxins/acids

Answer 3

Aerobes: High proportion of young plaque Usually don't cause harm e.g. Neisseria subflava Faculative anaerobes: These are the majority of microbes in the mouth Able to survive and grow with high/low oxygen concentrations Usually gram positive e.g. streptococcus mutans ``` Obligate anaerobes: High numbers in mature plaque O2 is toxic or inhibitory to growth Some of these species are harmful and may be associated with gum disease eg. Fusobacterium nucleatum ```

Answer 4

Eukaryotic Absorb nutrients by breaking down organic material into simple molecules

Answer 5

Moulds - filamentous fungi Yeast - predominantly unicellular

Answer 6

Skin, hair, nails, mucous membranes Eg. dermatophytes - athletes foot Candida - Thrush malassezia - dandruff or Pitryiasis versicolor

Answer 7

Through puncture wound Rare infections, disease develops slowly Very difficult to treat Black moulds eg. chromoblastomycosis Madurella mycetomatis - madura foot

Answer 8

Single deep organ or disseminated

Answer 9

``` Primary pathogens: (can cause disease in healthy people) Histoplasma capsulatum Blastomyces dermatitdis Parracoccidioides brasiliensis Coccidioides immitis ``` ``` Opportunistic pathogens (only infect immunocompromised): Candida sp. Aspergillus sp. Cryptococcus sp. Pneumocystis jirovecii ``` both kill a lot of people

Answer 10

3 genera: Microsporum sp. Epidermophyton sp. Trichophyton sp. Filamentous fungi From soil, animals and people Produce keratinise: Digest keratin as a growth substrate Therefore infect keratin rich tissues

Answer 11

Anthropophillic - host is man, eg. trichophyton - chronic athletes foot Zoophillic - reservoir is animals, can infect man produces the most severe inflammatory reaction eg. microsporum canis in cats and dogs Geophillic: Found in soil, occasionally pathogenic

Answer 12

present in mouth, GI tract, women genital tract Can infect normal people but infects more on people who are on antibiotics, diabetes or pregnancy

Answer 13

Infect healthy individuals Route of infection is inflation of spores Geographically limited - common in endemic regions Histoplama infects 500,000 in US every year All thermally dimorphic: Saprophytic filamentous form at 25 degrees Parasitic form at 37 degrees Disease: Asymptomatic Mild respiratory infection Can progress to be more lethal

Answer 14

Single organ or widespread | Affects immunocomprimsed people who people have undergone surgery

Answer 15

FIrst reported in Japan 2009 Causes both superficial and systemic disease Key concerns: Multi drug resistant Misdiagnosis Hospital outbreaks

Answer 16

Most don't cause disease Route of infection by inhalation of spores or sick building syndrome Only 4 cause disease 200 don't - A.fumigatus, A. flavus, A. niger and A. Terreus ``` Types of disease: Allergy TOxins in food Invasive bronchopulmonary Aspergillosis in immunocomprimsied Disseminated aspergillosis ```

Answer 17

Cryptococcus neoformans and crypto coccus gattii are causative Dimorphic Capsulate yeast in clinical setting Found in soil and avian habitats Route of infection though inhalation and sexual cycle producing small spores Disease: Cryptococcosis Meningitis

Answer 18

Causative version is pneumocystis jirovecii Disease: Pneumocystis pneumonia Dry cough AIDs defining disease Route of infection through inhalation We can't culture it Genome sequence: Lacks genes for amino acids biosynthesis So scavenges them from the host

Answer 19

Adhesion and colonisation Epithelial penetration Vascular dissemination (spreading in bloodstream) Endothelial colonisation and penetration

Answer 20

``` Adhesion to host surfaces Invasion of epithelial Penetration beyond epithelia Obtaining nutrients Opposing host defences ```

Answer 21

Flushing mechanisms Molecular recognition Phagocytosis and killing Immune response

Answer 22

Diploid organisms - 8 chromosomes Largely asexual Polymorphic fungus CUG codon reassigned

Answer 23

``` Yeast - buds Pseudohyphae - buds mixed with hyphae Hyphae - long filaments Opaque - see through buds Chlamydospore - branch of from hyphal cells, tough cell at end, form in nutrient poor environments ```

Answer 24

``` Temperature above 35 degrees Serum Neutral pH High pCO2 Low O2 Nitrogen or carbon starvation Matrix embedded growth ``` Quorum sensing: High cell densities causes hyphal growth

Answer 25

Manoproteins on cell surface Als3 is very important

Answer 26

``` Invades normally non-phagocytic host cells Invasion generally hyphal specific 2 main routes: Induced endocytosis Active penetration ```

Answer 27

Fungal invasion interacts with host cell surface proteins Interaction triggers final engulfment through endocytosis 'zipper like' mechanisms

Answer 28

Pushes itself into host cells or between junctions potentially involves: Physical force from directional growth and turgor pressure Secreted hydrolytic enzymes degrading host tissue

Answer 29

Form on a variety of biotic and abiotic surfaces Structured assemblies encased in extracellular matrix Display inherent resistant to antifungals and host defences Quorum sensing and polymicrobial interactions impact on formation

Answer 30

Attachment - adherence of yeast cells to substrate Initiation - formation of micro-colony Maturation - hyphal development and ECM production Dispersal - release of non adherent yeast cells

Answer 31

Hydrolytic enzymes play a role in obtaining nutrients, combatting host defence and adhesion

Answer 32

Reductive pathway Siderophore uptake Haemoglobin uptake and degradation

Answer 33

Phagocytosis: Change in pH Low amino acid availability Lack of glucose and iron ``` Respiratory burst (rapid release of reactive oxygen species ): Reactive oxygen and nitrogen species ``` Cytokine burst: Inflammatory response Elevated temperature

Answer 34

Membrane disrupting agents: Polyenes Ergosterol synthesis inhibitors: Azoles, allylamines DNA synthesis inhibitors: Flucytosine Glucan synthesis inhibitors: Echinocandins

Answer 35

Associate with ergosterol to form pore structures Cause membrane leakage Cause cell death (fungicidal) ``` Examples are: Amphotercin B (AmB), and nystatin ``` Wide spectrum Not available orally - only used in hospital Only problem is nephrotoxicity - damage of the kidney

Answer 36

Fungi version of cholesterol in mammals So it stabilises the phospholipid bilayers They are so similar its difficult to not harm host cells when using drug

Answer 37

Synthetic compound Contain Azole rings - used now is triazoles (3 nitrogens) Examples are Fluconazole, Voriconazole, and Isavuconazole Inhibit ergosterol synthesis by inhibiting 14a sterol demethylase which blocks heme iron in the enzyme This alters membrane fluidity due to build up of 14a sterols Broad spectrum Problems: Drug interactions - enzyme related cytochrome P450 which is used in human liver in drug metabolism Resistance forms

Answer 38

Synthetic compound Inhibits ergosterol biosynthesis Cells accumulate squalene which kills them Fungicidal against dermatophytes and poor activity against other species

Answer 39

Example is 5-Flucytosine - (initially a anti cancer treatment) Enters fungal cells via cytosine permease - converted to 5 fluorouracil which insist protein synthesis and DNA syntheses Only works on yeast Resistance is very common so used very often

Answer 40

Semisynthetic Inhibit B1, 3-Glucan synthase which is essential component of cell wall Fungicidal against candida Fungistatic against aspergillus No problem of cross resistance and aren't very toxic Problems: Not available orally and are expensive

Answer 41

Intrinsic resistance - naturally doesn't work on them

Answer 42

Susceptible strainbecomes resistant through mutation and selection - (in fungi horizontal gene transfer can't occur)

Answer 43

Reduced ergosterol content Alteration of sterol/phospholipid balance Increased catalase activity to combat oxidative stress

Answer 44

Loss of permease activity Loss of cytosine deaminase activity Decrease in the activity of uracil phosphoribosyl-transferase

Answer 45

Point mutations in B1, 3-Glucan synthase Up regulated chitin synthesis (only in vitro)

Answer 46

Reduced intracellular accumulation - More efflux pumps Target site alteration Upregulation of target enzyme - overcomes competitive inhibition (only subtle) Alteration in sterol synthesis - cross resistance to polyenes

Answer 47

Increasing use of prosthetic devices within the modern hospital (Kojic and Darouiche 2004) 95% of cases of urinary tract infections are associated with catheters (Darouiche et al 2001) Biofilms in comparison to planktonic cells are generally much more resistant to antibiotics and biocides

Answer 48

Plankton in the sea? This is affected by climate change from the warming of the water Ocean heat capacity measured rather than surface temperature as more reliable

Answer 49

``` Found in water Its a gram - rod Doesn't form spores It's motile Anyone is susceptible It's infectious, transmission via the fecal oral route Exposure from contaminated food or water Treatment through antibiotics and fluid replacement Been used as a biological weapon Has 2 chromosomes ```

Answer 50

Growth of it | Phytoplankton blooms

Answer 51

Growth of it | Expression of Vibrio cholerae toxin

Answer 52

Survival of it | phytoplankton blooms

Answer 53

Growth of it

Answer 54

Growth | Expression of toxin

Answer 55

Growth of V. cholerae | Attachment to exoskeletons

Answer 56

Say why and who this affects (businesses) Apply this sort of thinking in essay

Answer 57

Underline it

Answer 58

Form a biofilm which protects them from the immune system Also allows them to replicate

Answer 59

The microorganisms that typically inhabit a specific environment

Answer 60

The totality of microbes, their genomes and environmental interactions in a defined environment. e.g. the gut of a human, soil sample

Answer 61

Microbial imbalance on or within the body

Answer 62

Firmicutes and Bacteroidetes

Answer 63

Involved in immune system regulation remove toxins and carcinogens, crowd out pathogens (colonisation resistance), improve intestinal functions, gut-brain links in communication, as important to us as a liver- because of metabolites produced in gut. Considered as a vital organ

Answer 64

from birth to later years (critical inoculation in infancy/birth).

Answer 65

, surface tissues (skin & mucous membranes and gut) are constantly exposed to environmental microorganisms and are readily colonized by diverse microbial (primarily bacterial) species

Answer 66

Highly parallel DNA sequencers combined with high-throughput mass spectrometers enable characterization of whole microbial communities including Genomes, proteins and metabolic products

Answer 67

Determine whether individuals share a core human microbiome Can changes in the human microbiome be correlated with changes in human health?

Answer 68

Improved culture methods Perform genome sequencing in the absence of culture

Answer 69

There is the core part which majority of all humans have this set of genes Then there is a variable area which smaller subsets of humans have these genes

Answer 70

The GI tract, contains more than 70% of microbes in the body

Answer 71

Strict anaerobes outnumber facultative aerobes & aerobes Gut microbiota is dominated by just two phyla Bacteroidetes (e.g. Bacteroides) Firmicutes (e.g. Clostridium) Bacterial abundance increases as we progress from the stomach to the colon Colonization begins at birth, during passage through birth canal

Answer 72

It's a beta Proteobacteria Gram negative Carriage in the nasopharynx in 10-15% of the population Epidemics occur every 10-12 years Meningitidis belt in Africa where rates of infection can be 1 in 100 Classified by serogroup – reactivity to a bacterial polysaccharide capsule Can turn their capsule on and off There are 12 serogroups, 6 of which can cause epidemics Carriage is facilitated by downregulation or loss of capsule expression, as this sterically inhibits adherence and biofilm formation. However, survival in the bloodstream and in epithelial cells is enhanced by capsule expression

Answer 73

Example is Corynebacterium diphteriae Gram positive, immotile rod Colonises upper respiratory tract Route of infection: Airborne droplet Produces exotoxin Kills surrounding host cells Toxin spreads systemically Principally affects: Heart and Lungs Main cause of mortality Classic AB toxin - the main virulence factor (B is the binding factor)

Answer 74

first formally recognized bacterial carcinogen ability to induce gastritis, peptic ulcers, gastric cancer and mucosa-associated lymphoid tissue lymphoma has been confirmed. Susceptibility is multifactorial e.g. H. pylori virulence, environmental factors, genetic susceptibility of the host and status of host immune system. Difficult to eradiciate Gastric carcinoma development may be a result of host genetic, environmental and microbiological factors.

Answer 75

Anti-inflammatory commensal bacterium identified by gut microbiota analysis of chronic disease patients

Answer 76

A shift in the relative abundance of Bacteroidetes and Firmicutes has been observed in obese humans Furthermore, abundance of Bacteroidetes increased when dieting, with the change in abundance correlating with weight lost

Answer 77

Gastic acid in stomach Paneth cells, Pancreatic enzymes, bile, intestinal enzymes, GALT, and peristalsis from the intestines Intestines also produce lysozyme and cryptins

Answer 78

Low pH of urine and vaginal epithelia Urea and other toxic metabolic end products in urine Hypertonic nature of kidney medulla Flushing with urine and mucus

Answer 79

Have adherence factors Normally multi factorial

Answer 80

Leukocidins - Kill white blood cells including neutrophils and macrophages Produced by Stapylococcal and Streptococcal spp Coagulase - Causes fibrin clots to form in the blood of a host. Advantageous to the bacteria in evasion

Answer 81

Neourotoxins - cause paralysis Enterotxins - cause sickness and diarrhoea Cytotoxins - cause cell death

Answer 82

Faecalibacterium promotes the production of anti-inflammatory cytokines