Micro Flashcards

Question

how to distinguish aspergillus vs mucor?

Answer 1

acute angle hyphae vs right angle hyphae

Answer 2

ground glass on CXR, exudate w/ plasma cells, hypoxia

Answer 3

candida albicans

Answer 4

mainly endo but can be exo from room contaminated equip or person to person

Answer 5

Cutaneous infections occur in areas where skin surfaces occlude and are moist (i.e. armpits, groin, in between toes) and underneath toe/fingernails; Hematogenous candidiasis results in seeding of Candida into deeper tissues like the heart, eyes, bones/joints, and brain

Answer 6

Skin scraping and KOH, Culture to ID species level for later antifungal treatment choice, CHROMagar allows detection of mixed species of Candida vs Antifungal resistance and biofilm formation complicate treatment, Remove nidus of infection to increase treatment success, Prevention is preferable to treatment (Avoid broad spectrum antimicrobials, meticulous catheter care, rigorous adherence to infection-control precautions, better hygiene practices)

Answer 7

- Often multidrug resistant (some resistant to all antifungal classes) - Difficult to identify and can be misidentified leading to inappropriate management - Causes healthcare outbreaks (Spreads easily between hospitalized patients and nursing home residents) - 30-60% mortality in patients with C. auris (however, it is typically a secondary infection)

Answer 8

C. gattii and C. neoformans

Answer 9

- Microscopy of CSF by gram stain or India ink or other stains show encapsulated budding yeasts - Direct detection of the capsular polysaccharide antigen (CrAg) in serum or CSF (Doesn’t differentiate C. gattii from C. neoformans --> use CGB agar to differentiate: yellow = neoformans, blue = gatti)

Answer 10

cryptococcomas

Answer 11

-Pulmonary – presents like pulmonary aspergillosis Fungi can invade into pulmonary vessels (angioinvasion) causing infarction, embolism and thrombosis -Hemorrhage with hemoptysis (can be fatal) -Associated with cancer patients on chemotherapy and organ or stem cell transplant recipients (neutropenic) -Gastrointestinal – can lead to hemorrhage and/or perforation; more common in children and young infants -Cutaneous – most common form in immunocompetent individuals; can also result from hematogenous dissemination -Disseminated – infection spreads and involves the brain

Answer 12

direct contact, not in environ or animal. No immune response to keratinized surfaces --> infxn is chronic and persistent

Answer 13

Geophilic – environment to humans or animals Zoophilic –animals to humans Geophilic/zoophilic are inflammatory and respond well to therapy Anthropophilic –from person-to-person Chronic, relatively non-inflammatory, difficult to cure

Answer 14

- Infect skin, nails or in/on hair shaft – ectothrix, endothrix, favic - Tropism for keratinized tissue, secrete keratinases that can degrade cutaneous tissue but DO NOT invade deeper into the subcutaneous tissue - Risks included weakened immune system, public showers, locker rooms, sharing personal items i.e., hairbrushes, clothing, hats

Answer 15

- Spore enters body by direct inoculation/small break in the skin - Spore can be inhaled to cause pulmonary disease - Can become disseminated; seen in people with compromised immune response (HIV, COPD, diabetes, alcoholism)

Answer 16

- Cutaneous: small painless nodular lesions that grows and often becomes ulcerated and are slow to heal - Pulmonary: cough, dyspnea (shortness of breath), chest pain, fever - Disseminated: can spread by lymphatic system, signs depends on tissue infected

Answer 17

caused by Fonsecaea pedrosoi. Dematiaceous (naturally pigmented) molds In situ, Medlar bodies or copper penny bodies that are chestnut brown (melanin), thick-walled cells w/ septa Transmitted from environ to person dx: skin scrapings, KOH prep, microscopy tx: extremely difficult! Cryo- or heat therapy *Squamous cell carcinomas can occur within chronic lesions*

Answer 18

branched septate brown hyphae. transmitted by inoculation of contaminated material into a break in the skin; not infectious --> can't go person to person. sx: pigmented (gray to black) macule(s), no scaling or invasion of hair follicles, patches are non-inflammatory. dx: skin scrapings (KOH), confirm with culture. tx: topical azole

Answer 19

Macroconidia: Smooth-walled, borne in clusters of two or three; microconidia: absent; hair invasion: none vs Macroconidia: Numerous, large, thick and rough-walled; microconidia: rare; hair invasion: ectothrix vs Macroconidia: Smooth-walled, rare; microconidia: numerous, spherical teardrop or peg shaped; hair invasion: endothrix

Answer 20

microbe must be found in all orgs that are sufferring the dz and not in healthy orgs, microbe must be isolated from dzed org and be grown in pure cx, that cx should cause the exact dz when inoculated to healthy host, microbe should be reisolated and grown in cx and be identical to orig microbe

Answer 21

not all microbes can be grown in lab, not all microbes cause same dz to everyone equally, some microbes can cause diff dz's, one dz can by caused by mult microbes

Answer 22

an oval coccus vs curved, comma-shaped rod vs rod with tapered ends

Answer 23

Hepadnaviridae, Herpesviridae, Adenoviridae, Parvoviridae, Poxviridae, Papillomaviridae, Polyomaviridae. 2x stranded x/ Parvoviridae

Answer 24

retrovirus, togavirus, flavivirus, coronavirus, hepevirus, calcivirus, picornavirus. Retroviridae = dsRNA --> double layered capsid

Answer 25

All neg sense are enveloped and have helical capsid | All non-enveloped have icosahedral capsid

Answer 26

viral attachment protein binds to protein or carb of specific receptor; binding has no energy or temp requirement. VAP on naked viruses = part of capsid structure, on enveloped viruses = inserted into viral envelope. some viruses need coreceptor w/ host cell

Answer 27

parasite develops a thick cell wall to protect against harsh environment or in nutrient-poor environment vs fertilized oocyte that is encysted (thick cell wall) and excreted into the environment vs after excretion, ova develop into sporozoites while encysted vs fertilized vs intermediate stage between ova and adult

Answer 28

tough exterior surface found on most helminths vs individual segments of tapeworms

Answer 29

inserted into cell membrane vs cytoplasmic extension, integral to cell membrane, in protozoa

Answer 30

generally multicellular, replicating by fission and hyphae formation; filamentous/wooly/hairy; saprobic phase vs generally single cell that replicates by budding; buds = blastoconidia, germ tubes = pseudohyphae; parasitic phase

Answer 31

rigid, contains chitin and beta glucan; has ergosterol instead of chol

Answer 32

mat-like structures formed by many hyphae vs asexual reproductive structures produced by aerial hyphae --> airborne dissemination

Answer 33

one phase to increase infectivity, one stage to grow and disseminate in host

Answer 34

asexual spores contained within a sporangia vs asexual spores with no containment

Answer 35

vectors vs metazoa (helminths) vs protozoa

Answer 36

metabolically inactive (vegetative or dormant); bacteria under stress; 1 chrm = surrounded by dehydrated cortex w/ keratin-like protein coat + dipicolinic acid vs metabolically active with triggers of mechanical stress, changes in environment (e.g., pH, water), or presence of specific nutrients (e.g., alanine)

Answer 37

process in which each bacterium in microenvironment produces a specific small molecule, and when enough bacteria (i.e., a quorum) are producing the factor, the behavior of all bacteria in the group changes in some way to benefit ALL bacteria; ex: biofilm production vs group of genes controlled by a single promoter that function together to generate a specific virulence mechanism; very often a type III secretion system vs group of genes with shared functions that are grouped together in a DNA sequence; a means to coordinate gene expression

Answer 38

viral RDRP makes neg template from pos mRNA --> RDRP makes more pos mRNA from neg template. ex: picorna, noro, toga, flavi, corona

Answer 39

newly transcribed pos mRNA in viral particle --> RDRP makes neg mRNA from pos template. ex: rhabdo, paramyxo, orthomyxo, bunya, filo

Answer 40

positive sense RNA genome = converted to complementary DNA (cDNA) via RNA-dependent DNA polymerase (reverse transcriptase (RT)) w/in virus --> cDNA = transported into the nucleus --> cDNA = integrated into the host cell DNA => provirus --> host DNA-dependent RNA polymerase transcribes the viral DNA sequence into mRNA --> full-length positive sense RNA progeny genomes

Answer 41

1. attachment/absorption: VAP binds to specific host receptor 2. penetration: virus uses energy and/or temp to penetrate capsid into cell 3. uncoating: - non-enveloped capsid releases genome into cyto/nuc => virioplexis - enveloped virus does membrane fusion w/ VAP - non/enveloped virus can do receptor-mediated endocytosis 4. replication: using host transcpxn/sln to replicate viral DNA 5. assembly: progeny virions made 6. release: progeny virions released and kills cell --> can infect new cells

Answer 42

o DNA viruses inhibit cellular DNA synthesis. o RNA viruses shut down synthesis of host RNA. o Production of viral proteins interfere with production of host proteins. o Viral genes or proteins can override growth regulatory signals in host cell. vs o Lysis as progeny virions = released o Compromised membrane integrity due to membrane loss as progeny viruses bud from host cell o Toxicity of newly synthesized viral proteins --> cytopathic effect/cytopathicity/cytopathogenesis

Answer 43

low vs high b/c no proofreading

Answer 44

favored development of particular virions (ones that have high virulence) vs minor changes in genetic sequence d/t random point mutations --> little effect on dz severity vs major changes d/t genetic reassortment --> significant effect on disease severity

Answer 45

sequence similarity between two distinct genetic elements --> can create new genotypic virions or a provirus vs single cell is infected with 2 genetically distinct viruses --> mix gene segments

Answer 46

mature virions = fully formed inside the cell --> cell lysis triggered --> release progeny virions vs o Exocytosis – viral proteins inserted in ER membrane --> assembled capsids enter ER and progress through Golgi --> transported to cell surface in vesicles “pinched off” from Golgi --> vesicles fuse with cell membrane --> expel virus o Budding – viral glycoproteins = inserted into cell membrane --> viral capsids form at the cell surface --> extrude from the cell membrane --> pinches off and seals --> release progeny virions

Answer 47

misfolded PROTEINS (no nucleic acid). natural form, 3 alpha helices, sensitive to proteinase K vs mutated form, beta pleated sheets, resistant to proteinase K. PrPC misfolds to PrPSC and enters brain (or random already mutated PrPSC enters brain ) --> PrPSC binds to PrPC --> PrPC becomes PrPSC --> undergoes conformational change in cyto and ER --> form fibrils --> fibrils break off and disseminate --> fibril formation at other sites

Answer 48

incomplete viral particles that are non infectious o Lack some genetic information required for replication and infxn o Partial or complete loss (empty viral capsids) o Can function as “immune decoys” – e.g., influenza virus, hepatitis B virus (HBV)

Answer 49

Multiple proteins translated from a single mRNA – each with defined start and stop sites; proks and pos sense ssRNA viruses vs One protein per mRNA strand; euks vs One long protein translated from mRNA, then cleaved into separate proteins; usually functionally related

Answer 50

standard medium vs contains extra supplements to encourage growth vs allows some to grow, but suppresses growth of others vs growth of different organisms produce different effects based on microbe’s physiology

Answer 51

inhibit bacterial growth and reproduction by inhibiting RNA synthesis --> Delay bacteria until host immunity can kill vs directly kill bacteria by inhibiting cell wall or DNA synthesis --> Not dependent on host response --> more rapid effect

Answer 52

complete removal of all microbial organisms – vegetative, sporulated, pathogenic and commensal organisms; only on inanimate objects vs elimination of MOST pathogenic, vegetative microorganisms; on inanimate objects

Answer 53

* Antisepsis – elimination of most pathogenic, vegetative microorganisms on animate objects; chemical treatments only * Heat – dry heat and wet heat (e.g., boiling). Most efficient form is autoclaving --> destroy all organisms, viruses, and spores, but may not denature prions * UV light – UV-A, UV-B, and UV-C causes thymine dimers to form --> mutations --> possible death * Ionizing radiation like X-rays and gamma rays * Chemicals that denature enzymes – challenges include generation of toxic waste that requires special disposal or incidental exposure to product (carcinogens); ex: Phenol derivatives (Lysol) and aldehydes (formalin), Chlorine and iodine, Heavy metals (mercury, silver, copper), Ethylene oxide * Chemicals that denature membranes like soap and alc

Answer 54

Soil-transmitted (feces outside contaminate food) - Southern US - Symptoms: rectal prolapse (mucus and blood in stool) - Children can have long-term complications (anemia, neuro) - Diagnosis via polar plugs - ova in stool

Answer 55

- Vector: Aedes or Mansonia mosquito - Results in lymphatic filariasis (lymphedema, possible elephatiasis) - Diagnosis: blood smears with microfilariae - must collect between 10PM and 2AM

Answer 56

peptidoglycan synthesis and β-lactam antibiotics vs 30S ribosomal subunit and aminoglycosides --> Aminoglycosides bind 30S ribosomal subunit --> inhibit initiation and cause misreading of mRNA codon --> protein mutation; 50S ribosomal subunit and erythromycin --> Macrolides (e.g., erythromycin) bind 50S ribosomal subunit --> inhibit tRNA translocation --> prevent peptide bond formation b/w amino acids vs DNA gyrase makes cuts to relieve tension of DNA strand as it is unwound during replication; Quinolones (e.g., ciprofloxacin) bind DNA gyrase (topoisomerase II) and topo IV causing release of cut DNA – a fatal event vs mycobacterial mycolic acid synthesis and isoniazid vs exotoxins and vaccine-induced antibodies

Answer 57

transmitted by tsetse fly from Africa (East and West)