Microbiology

Question 1

Which are the microorganisms produce intraerythrocytic infections? and which are their characteristics?

Answer 1

• babesia—- intraerythrocytic rings, vector— tick—coinfection with borrelia (lyme disease)
• plasmodium spp

Question 2

Which streptoccocal components produce scalet fever?

Answer 2

erythrogenic toxin

Question 3

which is the mechanism through influenzae virus achieve antigenic shift? and how explain it?

Answer 3

Reassortment: enchange genetic material, it is possible because of segmented genome.

Question 4

which is the cause and main characteristics of the renal struvite stones?

Answer 4

• Urease positive microorganisms: Proteus, Cryptococcus, H pylori, Ureaplasma,
  Nocardia, Klebsiella, S epidermidis, S saprophyticus
• Calculus fill entire renal pelvis

Question 5

Congenital toxoplasmosis triad

Answer 5

• Chorioretinitis
• Hydrocephalus
• Intracranial calcifications

Question 6

Relate these conditions with some parasites

• biliary tract disease and cholangiocarcinoma
• liver hidatid cyst
• microcytic anemia
• myalgias
• Vit B12 deficiency

Answer 6

• Clonorchis sinensis
• Echinococcys granulosus
• Necator- ancylostoma
• Trichinella spiralis
• Diphyllobothrium latum

Question 7

8 families of naked virus

Answer 7

Papilomavirus, adenovirus, parvovirus, polyomavirus, calicivirus, picornavirus, reovirus and hepevirus.

Question 8

7 families of DNA virus and exceptions

Answer 8

1. Herpesvirus, Hepadnavirus, Adenovirus, Polyomavirus, Poxvirus, Parvovirus, Papillomavirus
2. All are dsDNA except parvovirus
   - All replicate in nucleus except Porxvirus (carries DNA -dependent RNA polymerase)

Question 9

which are the main C. difficile pathogenic factor?

Answer 9

alpha toxin (phospholipase C) is a lecithinase—-disrupts membranes, damaging RBCs, platelets, WBCs, endothelial cells— massive hemolysis, tissue destruction, hepatic toxicity.

Question 10

Mechanisms of bacterial resistance to aminoglucosides

Answer 10

• poor drug penetration through bacterial membrane
• failure to drug binding to 30s ribosomal subunit due to mutation
• Drug destruction by bacterial enzymes

Question 11

ADHD treatment

Answer 11

Methylphenidate and anphetamines: Increase releasing of norepinephrine and dopamine from vesicular storage sites.
Blocking NE and dopame reuptake

Question 12

antibiotics against anaerobic bacterias

Answer 12

• piperacilin-tazobactam
• carbapenems
• clindamycin
• metronidazole

Question 13

Protein A

Answer 13

Part of peptidoglycan layer—virulence factor of S. aureus —- binds to fc portion of IgG— inhibiting complement activation and phagocytosis.

Question 14

Enterotoxigenic E. coli

Answer 14

heat level toxin (LT)
activate cAMP —- increased Cl in gut and H2O efflux
“Cholera like toxin”
travelers diarrhea

Question 15

• Candida

- Blastomyces

Answer 15

• Pseudohyphae with blastoconideas, budding yeast

- yeast with distinctive broad beased budding

Question 16

• coccidiomicoses
• Cryptococco
• Hystoplasma

Answer 16

• spherules with endospores
• capsule (india ink)
• small oval yeast within macrophages

Question 17

Legionella pneumophila

Answer 17

Silver stains
charcoat yeast agar suplemmented cysteine and iron
contaminates natural water
pneumoniae, diarrhea, hyponatremia

Question 18

Influenza virus vaccine

Answer 18

Inactivated version of vaccine—- inducing neutralizing abs against hemagglutinin antigen— prevents virus entering the cell via endocytosis

Question 19

Germ tubes

Answer 19

true hyphae—- specific for Candida albicans

Question 20

Primaquine

Answer 20

Mus be added to treatment regimen against P. vivax and ovale—- to erradicate hipnozoites

Question 21

Haemophilus

Answer 21

requires X factor (hematin) V factor (NAD+) to support growth.
Will grow around B hemolytic S. aureus because secrete factor V

Question 22

Streptococo

alpha, beta y gamma hemolytic

Answer 22

• alpha: viridans (optohin resistant and bilis insoluble). pneumoniae (optochin sensitive and bilis soluble)
• beta: pyogenes (pyr positive and bacitracin sensitive), agalactiae (pyr negative and bacitracin resistance)
• gamma: enterococcus (pyr positive, grow in 6.5% NaCl), bovis (pyr negative and not grow in 6.5% NaCl)

Question 23

coccidiodes immitis

Answer 23

dismorphic fungus
microscopic examination: thick wall spherules with endospores
immunocompetent localized infection: lungs
immunocompromised: systemic infection

Question 24

Streptococo pyogenes

Answer 24

Beta hemolytic
Coagulase- catalase negative
PyR positive
Bacitracin sensitive

Question 25

Q fever

Answer 25

Coxiella burnetti animal waste Acute: non specific fever- fatigue- severe debilitating headaches retroorbital, photofobia, pneumonia, thrombocytopenia, increase liver enzymes Chronic: fatal if is untreated, endocarditis if the patient has valvular disease

Question 26

Clostridium difficile enterocolitis

Answer 26

``` toxin A (enterotoxic) and B (cytotoxic) Toxin B more virulent: inactvated rho regulatory protein---------involved in signal transduction and actin cytoskeletal structure maintenance --- disrupction of intercelleular tight junction. Damaged cytoskeletal integrity ```

Question 27

Which is the main cause of septic shock and septicemia of meningitis by N. meningitidis?

Answer 27

Lipoolygosacharide (LOS) | Endotoxin

Question 28

Dynein and kinesin

Answer 28

In herpes zoster dynein: retrograde transport (skin to nerve) Kinesin: anterograde transport (nerve to skin)

Question 29

West nile virus

Answer 29

fever, rash and neurologic manifestations most common in erderly patients encefalitis and flaccid paralysis RNA virus-- flavivirus, transmitted by mosquito (culex)

Question 30

Saline microscopy

Answer 30

best diagnstostic test to identify trichomonas

Question 31

Why is the difficult to develop vit c vaccine?

Answer 31

has 6 o more genotypes----the virion encodes RNA dependent RNA polymerase without 3´-5´ proofreading exonuclease activity: results in many errors during replication. --- hypervariable genomic regions----such sequences coding envelope glycoproteins

Question 32

Acute hepatitis B

Answer 32

Systemic, skin, joint symptoms, hepatomegaly and elevated transaminases (> 10 times over normal limit). May develop a serum sickness like syndrome: joint pain, lymphadenopathy and prurituc urticarial vasculitis rash could or not be icteric Elevated Pt: poor prognosis

Question 33

three main mechanisms for genetic transfer between bacteria

Answer 33

- transformation: bacteria take up naked DNA for the environment. - Conjugation: DNA is passed from one bacterium to another by direct cell-cell interaction - transduction: bacteriophage - mediated transfer of genetic information

Question 34

Difference between reassortment and phenotypic mixing

Answer 34

phenotypic mixing: the progeny of new strain remain unchanged Ressortment: any genomic change is always present in subsequent progeny

Question 35

Hepatitis D and B relation

Answer 35

Hepatitis D antigen isconsidered replication defective as it must be coaled by exteral coat hep B surface antigen-------------to PENETRATE hepatocyte

Question 36

How could minimized recurrent HSV-2 recurrent lesions?

Answer 36

daily valacyclovir, acyclovir or famciclovir | minimized replication

Question 37

Novobiocin test

Answer 37

applying in coagulase negative microorganisms, sensitive: Staphylococcus epidermidis Resistant: S. saprophyticus

Question 38

The most mediator of sepsis?

Answer 38

TNF alpha

Question 39

Ecthyma gngrenosum

Answer 39

P. aeruginosa Exotoxin A (protein synthesis inhibitor) Elastase(degrades elastin--- blood vessel destruction) Phospholipase C (degrades cellular membrane) Pyocianin (generates ROS) *** perivascular bacterial invasion of arteries and veins---- dermis and subcutaneous tissue.

Question 40

Absolute neutrophil count

Answer 40

0.6* Number of leucocyte | If it is less than 500 /mm3 = neutropenia

Question 41

Roseola infantum

Answer 41

HHV 6 | 3-5 days with fever ------- then a blanching maculopapular generalized rash

Question 42

Ghon complex

Answer 42

initial infection of M. tuberculosis | lower lung lobe lesion (fibrotic focus) + ipsilateral hilar adenopathy

Question 43

Common intracellular pathogens

Answer 43

Chlamydia, francicella, laegionella, listeria, mycobacterium, N. gonorrhea, nocardia, ricketssia, salmonella and yersinia ** Cell mediated immunes response: INF gamma, TNF alpha, and IL-2

Question 44

outer membrane is characteristic of...

Answer 44

gram negative | contain: LPS and LOS

Question 45

Bacillary angiomatosis

Answer 45

produced muy bartonella henselae in immunocompromised patients (catscratch). Vascular lesions in skin as papules, and in viscera