SM Flashcards

Question

Resistance: CRE

Answer 1

CRE (Carbapenem-resistant Enterobacteriaceae): efflux of drug OR loss of outer membrane porins

Answer 2

• Life cycle of Schistosoma/Bilharzia/snail fever • Trematode (flatworm): S. Mansoni: Intestinal, stabbing spike, --> portal hypertension S. Japonicum: Asian intestinal, round --> portal hypertension S. Haematobium: urinary, lancet --> bladder cancer • Cercariae penetrate the skin--> blood vessels of bowel/rectum or bladder, mature into sexual adults and make eggs --> eggs passed from humans into water, eggs hatch and release miracidia--> miracidia penetrate snail tissue and mature into sporocysts --> cercariae released into water Dx: urine eggs

Answer 3

• Kirby-Bauer susceptibility testing: disk diffusion, spread known amount of bacteria evenly on a plate, incubate, organisms grows or dies depending on its MIC and diffusion rate of antibiotic, larger area of killing, greater suspetibility • MIC where growth meets no growth on the E strip Some subjectivity

Answer 4

• Blastomycosis ○ R: § Geography: southern, eastern USA, great lakes/ohio river valley § Transmission: inhalation of spores ○ C: patchy alveolar infiltrate on xray, lesions or cavities in lung, acute or chroni pneumonia § Can spread "systemic" in immunocompromised: disseminates to skin and bone (osteomyelitis) § Dimorphic: mold in cold, yeast in heat H: broad based budding, same size as RBC, urine antigen test

Answer 5

• Mycobacterium leprae • Thrives in cool temperatures (explaining predilection for extremities), acid-fast staining (mycolic acids) ○ Reservoir: armadillos, Hansen's Disease • Tuberculoid form: Th1 response with cell mediated immunity, able to contain bacteria in macrophages, mild disease, ○ well demarcated, hairless, skin lesion ○ Lepromin skin test: test for immune reaction, positive: demonstrates good cell mediated response, like PPD skin test • Lepromatous form: Th2 mediated- humoral response, prevents containment of bacteria within macrophages, causes humoral response ○ Transmission: unknown, perhaps resp droplets, human-human ○ Neuropathy symmetric with glove stocking pattern ○ Numerous poorly demarcated skin lesions on extensor surfaces of extremities ○ Leonine faces • Tx: ○ Tuberculoid: dapsone, rifamapin 6 months Lepromatous: dapsone, rifampin, clofazimine 2-5 years

Answer 6

• Pseudomonas aeruginosa • Gram - bacilli, grape-like odor, catalase +, oxidase +, produces blue/green pigments when plated, obligate aerobe, encapsulated ○ Catalase + : therefore extra susceptible to chronic granulomatous disease • Transmission: environment contaminate • Diseases: ○ Hot-tub folliculitis: puritic papular ○ Ecthyma gangrenosum: Cutaneous necrosis if gets into systemic circualtion ○ #1 Nosocomial Pneumonia ○ #1 Respiratory failure in CF patients: because Cl- channel dysfunctional ○ Nosocomial UTIs/catheter infections ○ Osteomyelitis: IVDU, diabetics ○ Burn patients: feared complication of burn wounds, often fatal ○ Otitis externa • Toxins: Exotoxin A: ADP-ribosylates EF2 Treatment: Piperacillin, fluoroquinolones, aminoglycosides

Answer 7

• ESBL (Extended-spectrum beta-lactamases): produce beta-lactamase in periplasm that chews up the beta-lactams ○ Use combo- beta-lactam/beta-lactamase inhibitor drug combos Carbapenems effective

Answer 8

• Rhinovirus: pico virus family, RNA+, Naked, • Transmission: respiratory system, acid labile (therefore cannot go thru GI tract), transmitted though fomites (yucky hands) ○ Attaches to ICAM-1 on host cells to enter ○ Grows best at 33C (slightly cooler than body), therefore found in upper resp. tract • Translation: use host cell machinery--> polyprotein product, cleavage by viral packaged protease--> processed in cytoplasm MANY different serotypes, therefore tough to make vaccine, common cold!

Answer 9

• Herpes zoster vaccine: SHINGRX, adjuvanted recombinant vaccine, VZV glycoprotein plus t cell bosting adjuvant (our immune system gets worse when we get old and so shingles pops out when we age) Shingles: reactivation of VZV from dermatomal ganglia

Answer 10

• Streptococcus gallolyticus • Gram + , alpha or gamma hemolytic, but classified as Group D strep within B-hemolytic streps Blood stream infection associated with colon cancer

Answer 11

• Cephalosporins: inhibits trans-peptidase enzyme (penicillin binding protein), therefore no cross linking of peptidoglycans, therefore no stability to cell wall ○ Similar to penicillin ○ Bacterialcidal Time-dependent killing

Answer 12

• Fluoroquinolones: disrupts DNA synthesis--> inhibit DNA gyrase and topoisomeraseIV--> inhibits protein synthesis ○ Bacterialcidal ○ Gram - most effective Concentration dependent killing

Answer 13

• Respiration and fermentation • Respiration: O2 electron acceptor of NO3-, happens between 2 cell membranes/wall, more efficient • Lactose Fermentation: grows pink colonies on MacKonkeys Agar ○ E coli ○ Klebsiella pnemoniae ○ Enterobacteracie ○ Serratia • Maltose fermentation: G. meningitidus yes, G. gorrorehea no • Sorbitol fermentation: NOT EHEC, all other E. coli do Mannitol fermentation: s. aureus, grows golden

Answer 14

• Coxiella burnetii • Gram +, Obligate intracellular, SPORES • Transmission: spores in dirt, survives animals GI tract and poops out spores, transmitted to humans via aerosolized transmission ○ Reservoir: farm animals • Q fever: pneumonia, headache, fever, HEPATITIS NO RASH

Answer 15

• HHV-8: dsDNA, herpes virus, • Unique: Kaposi Sarcoma (AIDS/immune suppression) = erythematous on nose, mucous membranes (Gi tract, hard palate), extremities ○ Pathogenesis: angiogenesis by dysregulating VEGF • Infected B cells: primary effusion lymphoma • Transmission: sexual contact/kissing ○ AIDS pts, Elderly Russian men, African folks • Dx: microscopic, leukocytic infiltrate ○ Can be confused with Bartonella hensleae Tx: antiretrovirals for HIV+ pts

Answer 16

• Parvovirus B19: naked virus, smallest DNA virus, ssDNA • Transmission: respiratory droplet, TORCH • Kids: Slapped-cheek rash/Fifth disease/Erethema infectiosa ○ Rash starts on face and moves downward • Adults: join pain, arthritis, edema • SCD: aplastic anemia, cobweb look In Utero: Hydrops fetalis

Answer 17

• Klebsiella pneumoniae • Gram -, nosocomial (multi-drug resistance), lactose fermenter, non-motile, encapsulated, urease+ • Diseases: Pneumonia, UTIs ○ Alcoholics, Abscesses, Aspiration § Chest x ray for abscess might look like TB • Unique: current jelly-sputum Tx: Carbapenems

Answer 18

• Mycobacterium avium-intracellulare • Atypical mycobacterial infection with nontuberculous mycobacteria caused by 2 species of mycos ○ Immunocompromised people more susceptible (AIDS) cystic fibrosis • First presents as persistent cough, also fevers/diarrhea/malabsorption/weight loss, • Common in the environment and infect when inhaled or swallowed Macrolides used as prophylaxis in AIDS pts

Answer 19

• Viral replication: ss(+)RNA vs ss(-)RNA vs dsDNA vs retrovirus • -RNA: brings along own RNA polymerase, all single stranded, replicates in cytoplasm ○ EXCEPT: orthomyxovirus replicates in nucleus • +RNA: ○ EXCEPT reovirus is double stranded • DNA:

Answer 20

• Respiratory syncytial virus: ssRNA-, enveloped • #1 Lower respiratory tract illness in children: bronchiolitis, pneumonia, tracheobronchitis, croup • Recurrent wheezing common following severe infection • Dx: antigen detection, RT-PCR • Prevention: monoclonal antibodies for high risk Tx: nebulized hypertonic saline

Answer 21

Cytochrome: bacteria containing cytochrome c = oxidase positive

Answer 22

• Francisella tularensis • Gram - , coccobaccili (radish-like), Tularemia • Transmission: rabbits (meat, direct contact) or through tick vector (dermacentor), CAN BE AEROSOLZIED ○ Tick bite ulcerates to introduce bacteria ○ Goes into macrophages ○ Travels through lymph system to reticular endothelial organs (lymph nodes) ○ Causes caseating necrosis § Swells and make palpable lymphadenopathy of nodes § Can spread systemically to other nodes • Facultative intracellular ○ Therefore recovery depends on cell mediated immunity ○ Helps spread disease through body Tx: aminoglycosides

Answer 23

• Risk factors for disease acquisition: echinococcosis • Dog Tape worm, infected with cystic form of tapeworm, humans are intermediate host ○ Often asymptomatic, symptoms result from growth/expansion of cysts, cystic rupture can cause anaphylaxis § Within the cyst is the larvae ○ Dog injects cysts from viscera of sheep, humans accidentally ingest dog feces with eggs inside Ranchers & Shepherds at risk, worldwide

Answer 24

• Leishmaniasis ○ Visceral: Kala-azar, parasties in macrophages of reticuloendothelial system § Shows up like lymphoma, hepatosplenomegaly, amastigotes in macrophages in bone marrow § L. donavi, brazil, africa, indian ○ Cutaneous: skin, more common, world wide § Old world: limited to skin, self limited, scar § New world: L. braziliensis, L. mexicana, L. panamensis more difficult to treat, spread to mucosa (worry about this!) ○ Transmission: sand fly injects promastigote into human, transforms to amastigote in macrophages § Human to human, with sand fly in between, zoonotic Testing: skin biopsy/culture

Answer 25

Oxidase: oxidase test detects cytochrome c, measures ability of bacteria to oxidize and change color of NNdeimehtylppenlendiamine

Answer 26

``` • Life cycle of Plasmodium spp. • Injected from mosquito as sporozoite--> infect hepatic macrophages, transform from schizont and asexual replication and release merozoites--> merozoite infects RBC--> mature into trophozoite (differences based on spp.) form either--> gametocytes (small proportion) to mosquito (sexual phase) OR schizont to merozoites to new RBC • Timelines: ○ 1 day: P. knowlesi, monkey reservoir ○ 2 days: p. vivax, p. ovale ○ 3 days: p. malariae Erratic: p. falciparum (kinda 48 hours) ```

Answer 27

• Pili/fimbrae: long thin filamentous, all over surface of cell, composed of pilin, mediate adherence to host tissues, pili bind to receptors that consist of sugar resides on glycolipids/glycoproteins in the host cell, therefore ay types of pili, determines tissues specificity of many bacterial pathogens • Sex pili: important in bacterial conjugation Changing expression of pili: phase varition or antigenic variation

Answer 28

• Glycopepetides: binds to d-ala-d-ala and blocks transpeptidase activity ○ Ex: vancomycin Bacterialcidal

Answer 29

Antiretroviral therapy targets: two nucleoside analogues plus integrase inhibitor or protease inhibitor

Answer 30

• Concentration: work best when concentration is very high relative to the MIC, ○ cmax/mic ○ High-dose or extended interval dosing ○ There is a time frame when cmax/mic is very high, but also a "post-antibiotic effect" interval where drug concertation decrease to levels below the MIC and there is persistent suppression of growth § The high the drug concentration the longer the duration of the PAE and the smaller the residual bacterial population when the next dose is given • Time: "Time above the MIC" hours time/mic, want more than 40-50% of time usually Alternative dosing to maximize time/MIC

Answer 31

• Candidiasis ○ R: normal flora ○ C: § Baby: severe diaper rash § Oral: immunocompromised or steroids, can scrape off white mucosa § Esophagitis: AIDS defining illness, white psudomembranese, CD4 count 100 § Vaginal candidiasis: diabetics, antibiotics, birth control □ Does not change pH of secretions (4 pH) § Endocarditis: tricuspid valve, IVDU § Systemic: dimorphic, yeast form with pseudohypi in cold (20C), germ tubes in heat (37C) ○ H: catalase + (individuals with chronic granulomatous disease esp. suseptible) KOH prep

Answer 32

TSST-1: exotoxin, toxic shock syndrome, staph aureus, super antigen

Answer 33

• Chagas disease ○ American Trypanosomiasis: T. cruzi, zoonotic, many animal hosts tough to eradicate, WESTERN HEMISPHERE ○ Transmission: kissing bug/reduviid bug, blood meal and deposits feces into the bite/eye § Inoculated as trypomastigote which circulates, can get taken up by another bug and complete life cycle in vector □ Affinity for cardiac muscle and smooth muscle of GI tract ○ Disease: chagoma: inflammatory lesion at site of entry (Romana sign: swollen eye) ○ Disease: cardiomyopathy, pseudocyst filled with amastigotes within cardiac tissue ○ Disease: megacolon, megaesophagus, loss of muscle tone Testing: Blood smear for trypanosomes, Serology, heart histology

Answer 34

Ebola virus vaccine: vaccine in development, it works, moAB

Answer 35

• Antifungal agent mechanism of action • Amphotericin B: polyene: binds ergosterol, disrupts fungal cell membrane (like penicillin but make if FUNgi), significant toxicity • Azoles: inhibit ergosterol synthesis, broad spectrum, safer • Allylamines: terbinafine: inhibits squalene epoxidase (eralier step in the sterol synthesis) • Echinocandins: inhibit cell wall glucan synthesis, impairs cell wall stress tolerance ○ First choice empiric anti fungal in hospital, IV Fungal cell wall: ergosterol vs. Mammalian cell wall: cholesterol

Answer 36

Gram-positive v. Gram-negative: gram+ takes up crystal violet stain in cell wall based on high peptidoglycan content

Answer 37

• Staphylococcus saprophyticus • Gram + cocci, novobiocin-resistant, catalase +, urease +, coagulase - Diseases: UTIs, especially young sexually active women

Answer 38

• Viridans streptococci • Gram +, optochin-resistant, alpha-hemolytic, bile-insoluble/resistant, NOT encapsulated • Diseases: dental caries ○ Subacute endocarditis of damaged heart valves (most commonly mitral valve) § Pathogenesis: adhere to fibrin platelet aggregates by producing dextrans that make the bugs stick Tx: Macrolides, Cephtriaxone

Answer 39

• Listeria • Gram + baccili, Beta-hemolytic, survives at cold temperatures • Transmission: soft cheese/milks, pregnant mom->baby • Unique: flagella outside cell tumbling motility, inside cells use actin rockets and propel from one cell to another without leaving (Immune evasion) • Unique: pregnant women more susceptible, DON’T EAT SOFT CHEESE, can be passed to baby or early preg. Terminate • Unique: babies and old people especially susceptible • Baby: 3rd common cause neonate meningitis Tx: Ampicillin

Answer 40

• Influenza A and B viruses: orthomyxovirus, RNA-, enveloped • Unique: replicates inside the nucleus, segmented (therefore antigenic shift/drift) ○ Antigenic drift: point mutations in genome, slighlty altered (new flu shot needed), responsible for seasonal flu ○ Antigenic shift: RNA shared between different species (H and N reassortment), responsible for pandemics § A: pandemic/epidemic, drift and shift § B: endemic outbreaks, drift ○ Hemagglutinin (HA): glycoprotein on surface of influenza viruses, binds to sialic acids on upper resp. tract., causes RBCs to clump together in test tubes § HA antigens: H1, H2, H3, etc. determines cell tropism (cells that can be infected by virus) ○ M2 protein: needed to create proper pH for viral encoding § Amantadine/rimantadine inhibit M2, old treatments for FluA ○ Neuroaminidase (NA): cleaves sialic acid to release newly formed virions from infected cell § NA inhibitors: oseltamivir/anamivir ○ Transmission: resp. droplets, dec-feb § Give Vax in october □ Live attenuated nasal spray □ Injectable: killed version ○ Pneumonia: major complication, staph aureus common culprit ○ Aspirin: contraindicated in children with viral illnesses: REYES SYNDROME: fatty liver/liver failure/encephalitis § Uncouples ETC in hepatic mitochondria • RT-Ascending paralysis from Guillain-Barre Syndrome associated with vax • Dx: rapid antigen test, RT-PCR

Answer 41

• Mycobacterium tuberculosis • Mycobacterium, acid-fast stained because of mycolic acids (carboyl fuschia stain), cultures very slowly, requires Lowenstein-Jensen media, obligate AEROBE, cell wall also has • Transmission: respiratory droplets, human to human, once infected lives in macrophages • Virulence: ○ Cord factor: glycolipid, serpentine shape, CRITICAL FOR Pathogenicity, sticky cell wall, once penetrates macrophages and induces TNFa, granuloma forms and remains walled off inside ○ Sulfatides: prevent phagolysosome fusion, creates incompetent secondary lysosomes/phagosomes in macrophages and allows TB to persist inside • Primary infection: infects lungs in middle lung lobes and involves hilar lymph node ○ Ghon complex: hilar lymphadenopathy + peripheral granulomatous lesion in middle/lower lung lobe ○ Tubercules: caseating granuloma, langerhans giant cells (activated macrophages) make walled off scarred area filled with necrotic macrophages ○ Symptoms: prolonged fever, most causes resolve by fibrosis and becomes latent infection, mostly children effected § Will have positive PPD, type 4 hypersensitivity test □ can be positive in active infection, latent, or BCG vaccines • Disease paths after primary infection: 1. Healed latent infection: resolve by fibrosis 2. Miliary TB: multi-organ failure, can seed multiple organs, lethal possible 3. Reactivation of latent infection: 5-10% of people, immune suppression downregulates TNFa allowing the TB to escape the walled off granuloma and reactivate i. Therefore: when starting patients on TNFa inhibitors, screen for TB first ii. Reactivation: upper lobes, 1. cough, 2. night sweats, 3. hemoptysis 1) TNFa: promotes wasting, produced in response to cord factor 2) Pott's disease: spinal column, damages vertebral bodies 3) CNS invovlement: cavitary lesion with tuberculoma • Tx: rifampin, isoniazid, pyrazinamide, ethambutol Prophylaxis: Rifampin, isoniazid (9 months!)

Answer 42

• Therapeutic drug monitoring: most commonly for vancomycin and tobromycin, want to avoid toxicity • Especially important in obesity and renal impairment • Trough monitoring • Substantial interpatient variability exists in serum concentration on standard drugs • Small diff between therapeutic and toxic doses You need an accurate asasy to measure this

Answer 43

Capsules: made of water, aids in avoiding the immune system/opsonization/complement activation

Answer 44

• Coccidiodomycosis ○ R: § Geography: southwestern USA § Transmission: inhalation of spores in dust, increased risk during dust storms/earthquakes ○ C: cough, fever, arthralgia, some radiographics may show cavities or nodeules some will be unremarkable, erythema nodosum on shins (robust immune response so only in healthy people) § Immunecompromised: disseminate to bone, skin, lung, meningitus § Dimorphic: mold in cold, spheriol of endospores in bodies -> ruptures and releases, larger than RBCs H: KOH stain/culture, serology IgM vs cocci

Answer 45

Catalase: reduces H2O2 into H2O and O2

Answer 46

Siderophores: remove iron from host molecules and take up into bacterial cells

Answer 47

Superoxide dismutase: degrades superoxide to hydrogen peroxide

Answer 48

toxic shock syndrome: superantigen, sticks APC MHCII and CD4+ T cell together, constitutive activation, cytokine release, tissue damage

Answer 49

``` • Proteus mirabilis • Gram - rod, flagellates, swarming-motility, fishy-odor, urease + (responsible for forming of struvite stones!) • Diseases: ○ UTIs ○ Kidney stones: stag horn calculi Tx: sulfonamides ```

Answer 50

• Wolbachia • Gram - Endosymbiont, most significant in oncocerca volvulus (transmit by black fly), the increased river blindness is associated with increased wolbachia present, generates much inflame response when the filariae die and release wolbaccie ○ Present in W. bancrofti, B. Malayi, O. volvulus ○ NOT PRESENT IN LOA LOA Tx: doxycycline kills off wolbachia without killing the microfilariae, but reduces blindness

Answer 51

• Streptococcus pneumoniae • Gram + lancet-diplo cocci, optochin sensitive, encapsulated, alpha-hemolytic, bile-soluble (cannot grow in bile) • Diseases: #1 ○ M-eningitus ○ O-titis media ○ P-nemonia: community-acquired, rust colored sputum, lower lobe ○ S-inusitis: • Virulence: ○ polysacc capsule ○ IgA protease • Unique: SCD pts particularly suseptible • Tx: Macrolide, Cephtriaxone • Prevention: ○ Adult vax: 23 valent, IgM, T-cell independent response Children vax: 7 valent, IgG, conjugated polysac to a protein to make more robust immune response with IgG

Answer 52

• Norovirus: ssRNA+, naked, one long polyprotein that is cleaved by viral proteases, replicates in cytoplasm • Calicivirus family • Outbreaks/Transmissions: cruises, close contact of humans, young children/schools/daycares, shellfish Diarrheal illness: viral gastroenteritis, explosive watery diarrhea

Answer 53

Peptidoglycan: protein made up of alternating NAG/NAM