2 - Microbiology Flashcards

Question

How is Epstein Barr Virus diagnosed? Tx?

Answer 1

``` Diagnose: 1) atypical lymphocytes 2) agglutination test for heterophile antibodies 3) ELISA for EBV antibody 4) PCR for EBV genes Tx: -typically self-limiting -treat symptoms -no vaccine available ```

Answer 2

-hallmark of mycobacteria -retain basic dyes within mycobacterial envelope when treated with acidic solutions -due to waxes (ie. mycolic acid) reducing permeability => neither gram (-) or (+) since stain can't penetrate ADV -> waxes make cell much more resistant to drying, allowing it to survive both in and out of the body ->also makes them resistant to killing in phagocytes ->still susceptible to heat (ie. pasteurization)

Answer 3

Transmission: - carried in "droplet nuclei" that can be aerosolized by coughing and sneezing - can remain suspended for hours, but prolonged exposure is typically required for infection -can also be ingested (M.bovis) in contaminated milk/milk products Stage 1: -seeding in mid-lower lung -multiply in alveolar spaces -ingested by alveolar macrophages and are killed or grow inside Stage 2: -logarithmic growth in macs -dissemination of infected macs via lymph and blood -NO HOST reaction for first 1-2wks Stage 3: -host humoral response -> activated macs/CD-8 T-cells destroy -form granulomas to "wall off" infection -> primary lesion Stage 4: -bacteria continue to multiply in granulomas, but are isolated from immune response -caseous necrosis in granulomas -lesions may heal, but bacteria is still viable inside Reactivation: -disturbance of immune surveillance and microbial growth -viable bacteria released to lung (typically) -Triggers-> diminished immune response, malnutrition, aging

Answer 4

Historical: decreased from '53-'84, but increased from '84-'92 largely due to HIV epidemic and immigration; steady decrease since '92 due to improved public health controls Current: highest rate in Africa and China, but incidence continue to fall -High Risk includes increased contact with persons infected with TB, low-income populations, ILLICIT DRUG use, HIV -small portion of those infected with develop symptoms

Answer 5

Culture is the "gold standard," but too slow for screening. PPD-T looks for a memory reaction due to previous infection with TB. Positive test criteria vary by population. >5mm is positive for: -HIV positive -recent contact with TB case -persons w/ fibrotic changes on CXR -organ transplants/immunosuppressed >10mm is positive for: -recent arrivals from high-risk populations -IV drug users -residents/employees of high-risk congregate settings -pre-disposing illnesses -children 15mm is positive for: -other ** PPD-T should only be conducted on those in high-risk groups

Answer 6

Drug combination therapy is now standard due to development of drug-resistant strains. (Rifampin and Isoniazid OR Rifampin, Isoniazid, and Pyrazinamide) To help with compliance, and thus fight development of resistance, Direct Observed Therapy (DOT) is increasing in popularity. XDR TB is resistant to ALL known therapies.

Answer 7

- Virus transmitted as aerosol and imbedded in respiratory epithelium. - local replication in epithelium cells - **damage to epithelium from the virus and the subsequent immune response makes the airway susceptible to SECONDARY BACTERIAL INFECTIONS - no viremia - immune response (macrophages, lymphocytes =>cytokines, INF-g) - antibodies to virus generated and clearance from tissue Secondary Infection occurs when person is re-infected, but their own symptoms are mild due to the IgA response. However, they can still infect others with the active virus.

Answer 8

- Abrupt onset! - headache - high fever (101-103F; higher in children) - myalgia - sore throat - non-productive cough - runny/stuffy nose

Answer 9

* *Secondary Infection -> injury to respiratory epithelium from virus and the subsequent immune response makes them more susceptible to infection - Bacterial (common)-> after improvement of symptoms, fever reappears with productive cough Step. pneumoniae, Staph. aureus, H. influenzae - Viral (rare)-> failure of infection to resolve, dyspnea, hypoxia, cyanosis, severe infammation of alveoli -> ARDS - Cardiac infection - Neurological symptoms: Guillan-Barre, encephalopathy, encephalitis, Reye's syndrome (associated with Aspirin use during infection)

Answer 10

1) Elderly (>65) 2) residents/nurses of chronic care facilities (prolonged exposure to >65) 3) chronic pulmonary/cardiovascular disorders(including asthma) 4) frequent/regular hospitalizations 5) 6mo-18yrs who receive chronic Aspirin 6) pregnant (2nd-3rd trimester) during flu season

Answer 11

- RNA virus (8 segments) - envelope - haemaggutinin (HA) and neuraminidase (NA) surface projections (spikes) that support attachment/fusion and release/disaggregation, respectively - membrane within viral envelope - membrane ion channel(M2) important for acidification of endosome

Answer 12

1) attachment to cell via binding of HA to surface receptor (sialic-acid glycoprotein) 2) migration to a coated membrane pit leading to endocytosis 3) acidic conditions in cell induces a conformational change in HA causing fusion of envelope and edocytotic vesicle 4) M2 membrane ion channel opens to allow inflow of H+ to vesicle, this induces uncoating and release of viral gene segments 5) viral gene segments migrate to nucleus where transcription AND RNA replication takes place (rare for RNA viruses) 6) glycoproteins made in ER, RNA in nucleus, then they are combined at cell membrane by budding 7) NA removes sialic acid receptors from virus membrane -> cannot be infected by another influenza virus 4)

Answer 13

1) Culture from throat swab/nasal wash in fertilized eggs 2) note cytopathic effects, immunofluorescence, hemagglutination 3) determine serotype (hemagglutination, complement fixation) 4) RT-PCR

Answer 14

Two mechanisms cause antigenic variation (mutation): 1) Antigenic shift: due to reassortment of the viral genome with animal variant -> requires animal reservoir (Type A Influenza) 2) Antigenic drift: consequence of natural mutations in genome during replication; more pronounced in influenza since the RNA dependent RNA polymerase has no proof-reading capability (Type A and B Influenza) (Type C Influenza is relatively stable)

Answer 15

1) Trivalent Inactivated Vaccine(TIV): intramuscular injection 2) Live Attenuated Influenza Vaccine (LAIV): nasal spray -> recommended for healthy patients 5-59y/o **both vaccines produce antibodies to the HA and NA surface proteins of the viral envelope Recommended for: -pregnant -caregivers/household with infant <6mo -healthcare and emergency medical personnnel -6mo-24y/o: due to increase risk of school age exposure and the preference of H1N1 for healthy 19-24y/o -25-64y/o with high risk medical conditions

Answer 16

Inhibit: Neuramindase(NA)-> prevents removal of sialic acid receptors from cell surface and budding of new virus=> inhibits spread of virus: -oseltamivir (Tamiflu) -zanamirvir (Relenza) Ion Channel(M2)-> prevents disassembly of virus in endocytic vesicle and maturation of HA glycoproteins=> inhibit cell infection and virus production -amantadine -rimantadine

Answer 17

Typical - high fever, shaking chills, chest pain, LOBAR consolidation seen on CXR -Agents: Strep. pneumoniae; Staph. aureus; Haem. influenzae, Gram neg enterics (nosocomial) Atypical - "walking pneumonia" - less severe, dry cough, headache, systemic aches, diffuse pattern on CXR -Agents: Mycoplasma pneumoniae, Chlamydia pneumoniae; Legionella pneumonia, influenza and other viruses, Coxiella burnetti

Answer 18

- tuberculosis | - fungal

Answer 19

- Gm+, diplicocci, lancet-shaped - alpha-hemolytic - catalase negative - colonies appear "mucoid" due to capsule - optochin sensitive* - bile soluble* * these characteristics help distinguish pneumococci from normal flora

Answer 20

Capsular polysaccharides - anti-phagocytic due to preventing complement (C3b) from binding to the surface - requires anti-capsule antibody for phagocytosis - however, ~90 serotypes of capsule prevent maintenance of immunity

Answer 21

1) previous/recent viral infection of upper airway(influenza) 2) compromised pulmonary function (alcohol, anesthesia) 3) age - very young (American indian>Alaskan natives 5) impaired immunity - sickle cell anemia, splenectomy/asplenia, HIV, myeloma, lymphoma, leukemia, etc

Answer 22

-sudden onset of fever, chills, pleuritic pain, rusty sputum, positive blood cultures (~30%) -typically a lobar infiltrate Complications - lung abscess, empyema, pericarditis, meningitis, intrapleural abscess, septic arthritis

Answer 23

- many are penicillin resistant ->empiric tx varies with time - different therapy is recommended based on the specific infecting orgamism

Answer 24

PCV13 (Conjugate Vaccine) - combination of 13 most virulent serotypes are conjugated to proteins to generate a T-cell dependent response, thus improving immunity of children 23PC (old version) - combination of 23 most virulent serotypes, but not conjugated Recommended: PCV13 ->children 6wks to 6yr; PS23-> everyone >65y/o

Answer 25

``` Bacterial: -Mycoplasma pneumoniae -Chlamydia pneumoniae -Chlamydia psittaci -Coxiella burnetti Viral: -Adenovirus -Parainfluenza virus -Epstein-Barr virus -RSV ```

Answer 26

- Entry via respiratory track - Attach at lower respiratory track via P1 adhesion (no invasion, just tight association) - Secrete CARDS toxi -> Lead to ciliostasis and vacuolization-> deteriorate cilia both structurally and functionally - Impaired clearance and mucous accumulation - Cell Mediated Immune response leads to additional tissue damage

Answer 27

Dx of exclusion - Cultures are difficult due to the specific growth requirements and ability to spread - serology shows a >4x rise in antibody - cold hemagglutinins is non-specific

Answer 28

- Antimicrobial can help with symptoms | - Antibiotics: Tetracycline, Erythromycin/Azithromycin, (NOT B-Lactams)

Answer 29

``` Elementary Bodies -small, dense -extracellular -Infectious form -metabolically inactive -disulfide cross-liked to membrane Reticulate Bodies -large -intracellular -replicative form -metabolically active -osmotically fragile ```

Answer 30

Elementary bodies(EB) attach to the outer membrane via disulfide bonds and promote endocytosis. Reorganization forms the Reticulate Body within vesicle. Multiplication within vesicle of RB. Antigen proteins are expressed on host cell surface, preventing further infection. RB convert to EB. Now appear as large cytoplasmic inclusion. Vesicle and cell lyse, releasing EB to continue infectious process.

Answer 31

Serology - IgM titer >1:64 OR 4x rise in IgG in a four week growth Culture - difficult and restricted to specific labs due to contagious nature

Answer 32

- air-conditioning cooling towers - Whirpool spas - sink taps and shower heads

Answer 33

- soil and water - fresh fruit and vegetables - whirlpools, sinks, respiratory therapy eat - common nocosomial contaminant

Answer 34

- immunosuppressed/AIDS - cigarettes - alcohol abuse - >50y/o - hematological malignancies - males>women

Answer 35

-Gram (-) (but do NOT take up stain well due to capsule) -specific culture req's= Buffered Charcoal Yeast Extract agar, amino acids, and iron -

Answer 36

Legionnaire's Disease - fever, chills, headache, malaise - diarrhea, nausea - interstitial pneumonia

Answer 37

- fever, sepsis | - tissue damage in airways

Answer 38

Gram (-) Flagellated strict aerobes Nonfermenters - use oxidative metabolism

Answer 39

- pneumonia in Cystic Fibrosis patients - burn infections - nosocomial infections - cellulitis - folliculitis - UTI - swimmers ear

Answer 40

- growth on MacConkey (lactose -) - oxidase (+) - pigment production (green) - glucose oxidation - grape bubblegum-like smell (characteristic)

Answer 41

One that can exist as either a mold or yeast.

Answer 42

Histoplasmosis Blastomycosis Coccidiodomycosis Paracoccidioidomycosis

Answer 43

- mold lives in soil with high nitrogen (bird/bat droppings --> guano) - disturbances to soil lead to aerosolization - spreads through aerosol transmission of SPORES

Answer 44

Inhaled as spores, mature to yeast form in lungs. Once phagocyosed by macrophages, they multiply and can be spread throughout the body. 2-3wks after initial infection, cellular immunity develops. This leads to granulomas to form. Some yeast form remain within granulomas and can cause relapses of the disease years later.

Answer 45

Most are asymptomatic. Pulmonary can be: 1)Acute - mild, self-limiting, fever, sweats, cough, headache/GI (sometimes) -diffuse pulmonary infiltrates 2)Subacute (weeks) - fever, sweats, cough, weight loss, hilar and mediastinal lymphadenopathy -focal/patchy pulmonary infiltrates 3)Chronic - fever, cough, sweats, weight loss -interstitial/consolidative infiltrates, bullae, calcifications **can lead to Progressive Disseminated Histoplasmosis -->can be fatal if not Tx quickly; most common in immunocompromised

Answer 46

Culture - 2-4wks for results Fungal stain - fast, but low sensitivity Serology - fast and sensitive, but several false +/- Antigen - fast, low sensitivity (best for disseminated disease)

Answer 47

Most are self-limiting -> no Tx Moderate - Itraconazole (anti-fungal) Severe - Amphotericin B (anti-fungal)

Answer 48

- Mold grows in soil and leaf litter - disturbances release spores - transmitted via aerosol * *dogs 10x more susceptible --> history of sick dog is big hint for blasto

Answer 49

- Spores inhaled and imbed in alveoli. - organisms change into yeast in lungs - multiply by budding (characteristic "broad base" budding from parent cell) - disseminated hematogenously before immunity develops

Answer 50

-most are asymptomatic -pulmonary, cutaneous, bone and genitourinary presentations Pulmonary: 1)Acute pneumonia - presents as atypical (walking) pneumonia w/ alveolar infiltrate -> no response to antibiotics -mass-like lesions can be mis-dx as cancer 2)Subacute/Chronic pneumonia - fever, sweats, fatigue, weight loss ** called the Great Pretender for its ability to present as other pathologies (bacterial pneumonia, Cx, etc)

Answer 51

``` Dx: -Histopathology -culture --> any colonies believed to pathogenic since not part of normal flora -serology - poor specificity Tx: Intraconazole, Amphotericin B ```

Answer 52

-most are asymptomatic Valley Fever/San Joaquin Valley Fever -> model planes-> dust -self-limited pneumonia (1-3wks after exporure) -fever, cough, chest pain, fatigue, shortness of breath, chills aches, night sweats, weight loss (potentially lasting for months) -Chronic (5-10%) can develop into a "cavernous lung disease with eosinophilia" -> this is rather specific for cocci.

Answer 53

``` Dx: -direct microscopy of sputum/tissue -culture -> must warn lab due to infectious nature -serology Tx: itraconazole/fluconazole, amphotericin B ```

Answer 54

- usually asymptomatic - acute, subacute, or chronic pneumonia - can develop into a disseminated disease (chronic mucocutaneous ulcers, meningitis)

Answer 55

``` Dx: -direct microscopy -tissue biopsy -culture Tx: itraconazole, amphotericin b ```

Answer 56

Histoplasmosis: mold - white/brown hyphal colonies -> large balls w/ spikes yeast - "dot disease" - small,intracellular, uninucleate ovals Blastomycosis: mold - white/tan filamentous colonies - > small conidia on terminal hyphae yeast - spherical, multinucleated, thick double-contoured walls Coccidioidomycosis: mold - barrel shaped, segmented hyphae yeast - collections of arthroconidia collect as spherules Paracoccidioidomycosis: mold - ?? yeast - round with multiple buds -> pilot wheel

Answer 57

Cystitis -> dysuria, frequent urination, suprapubic pain --> must rule out STI Pyelonephritis-> flank pain, fever, nausea, vomiting, chills, C-reactive protein, bacteremia (30%)

Answer 58

- Type 1 fimbriae -> reversible expression which allows them to either implant in bladder(ON) or ascend to upper tract (OFF) - P pili ->adherence in kidneys - Hemolysin ->damage cell membranes - Cytonecrotizing factor (CNF toxin) -> degrades actin cytoskeleton

Answer 59

- gram (+) cocci clusters - gamma-hemolytic (non-hemo) - catalase positive - coagulase negative * *Novobiocin resistant

Answer 60

Uncomplicated -> women, sexual intercourse, diaphragm/spermacide use, pregnant Complicated -> metabolic disorders that cause impaired urine drainage, stones Catheters-> chronic catheterization

Answer 61

Uncomplicated -> E. coli(enterobacteriaceae family), Staph. saprophyticus Complicated -> Staph. aureus, Staph. epididemis, Proteus mirabilis Catheter -> Enterococcus faecalis, Enterococcus faecium

Answer 62

Significant virulence factor for Staph. epi, Staph. aureus, Enter. faecalis, Psuedomonas aeruginosa, E. coli and Proteus mirabilis. Produces extracellular polymers that facilitate adhesion and protect microbes for antibiotics/host defenses. Detachment can lead to sepsis. VERY important in Catheter-associated UTIs

Answer 63

Member of Enterococcus family and is commonly involved in complicated upper UTI. Swarming motility allows it to "swim" up the ureter against urine flow. Produces characteristic "ripple pool" rings around initial culture. Indicates coordination in swarming pattern.

Answer 64

1) Specimen collection: a) voided ("clean-catch, mid-stream") specimen b) Catheter samples -> from "flowing" urine c) Suprapubic aspiration -> for those without bladder control (coma, infants) 2) Urinalysis: dipstick for chemical content, examine sediment for WBC, bacteria and/or urinary (granular) casts 3) Urine Culture: 0.1ml sample on plate, count colonies and multiple by 1000 to compare to "norms" given the collection system

2 - Microbiology Flashcards

Lectures: Bacterial Upper Respiratory Infections Viral Infections of Upper Respiratory Mycobacteria and Pulmonary TB Common Acquired Pneumonia Atypical Pneumonia Endemic Mycoses Urinary Tract Infection (88 cards)