Microbiology 3.1 Flashcards Preview

NMSK-B III > Microbiology 3.1 > Flashcards

Flashcards in Microbiology 3.1 Deck (35):
1

What are the common viral CNS pathogens which give rise to meningitis?

enteroviruses*
herpesviruses*
HIV-1

2

What are the common viral CNS pathogens which give rise to encephalitis?

herpesviruses*
arboviruses*
influenza virus
HIV-1
rabies

3

What is the difference in symptoms between viral meningitis and viral encephalitis?

viral encephalitis usually associated with more profound
1) mental status abnormalities
2) neurologic findings
3) seizures

4

What rae the common symptoms of viral encephalitis?

fever
headache
nuchal rigidity

5

What are the CSF findings of aspetic meningitis?

Normal/No:
-opening pressure
-clarity
-glucose
-gram stain/culture

Elevated:
-protein
-lymphocytes (WBC)

6

What are the enterovirus characteristics?

-picornaviridae
(small, ss linear RNA, virus)
-naked/non-enveloped
-replicate in cytoplasm

7

How does picornavirus replication occur?

-endocytosis (naked)
-release RNA in cytoplasm
-viral protein cap (5') and poly-A tail (3')
-polymerase with its own polymerase [big polyprotein cleaved into smaller proteins]

8

Where does picornavirus infect the body?

oropharynx
lymphoid
blood stream (meninges, brain, spinal cord)

9

What are the living conditions and seasonality of the enteroviruses genus?

GI
-low pH, 37o
-fecal-oral

summer and early fall

10

Which population is at-risk for enteroviruses?

children

11

How is enterovirus infection diagnosed?

RT-PCR using CSF or throat swab

12

What is the treatment for enteroviruses?

supportive, no treatment

13

What are the herpesviridae characteristics?

-enveloped
-large
-ds linear DNA
-replicates in nucleus

14

What is the prevention for enteroviruses?

hand washing
disinfection
hand sanitizer with alcohol >70%

15

What is the primary infection site and latent infection site of alpha herpesviridae (HHV 1-3)?

primary:
mucoepithelial cells

latent:
nerve ganglia

16

What are the main differences between HSV-1 and HSV-2?

HSV-1:
-"above the waist"
-latent in trigeminal gaglia
-orally transmitted
-children often infected
-70% adults infected

HSV-2:
-"below the waist"
-latent in sacral ganglia
-sexually transmitted
-sexually active people often infected
-25% adults infected

17

How do herpesviruses produce latent infections?

-after initial infection, infect nerves and "rests" as circular extrachromosomal unit in nucleus
-latency-associated transcripts (LATs) & noncoding regulatory RNAs which maintain latency
-reactivated and dislodges from nucleus
-meningeal branches to reach the brain

18

How is a herpesvirus infection diagnosed?

-Cowdry type A inclusions
-Tzanck smear (giant cells)
-PCR using CSF [rapid diagnosis for encephalitis or meningitis]

19

What is the most important anti-viral herpesvirus treatment?

IV *acyclovir* added to cell and becomes phosphorylated with herpes thymidine kinase (from virus)
-triple-phosphorylated with cell's own kinases
-enters nucleus and prevents DNA from being extended
**NOT A CURE**

20

What is the prevention for herpesviruses?

-safe sex
-gloves
-cesarean delivery if mother is symptomatic
-acyclovir for reoccurrances

21

What is the clinical presentaiton of varicella-zoster virus?

"chicken pox"
-infection (day 0)
-incubation
-contagious at 11 days
-fever begins at 13 days
-infection of skin/rash at 14 days

22

What is the at-risk population for varicella-zoster virus?

-children (varicella)
-elderly/immuno-compromised (zoster)

23

What is the pathogenesis of varicella-zoster virus?

highly contagious
respiratory secretions

24

What is it unsafe to contract a varicella infection as an adult?

-risk for pneumonia
-progressive infection leads to encephalitis

25

What is the latency and reactivation of varicella-zoster virus?

-latency in nerve ganglia
-when reactivated, expresses at that dermatome/spinal cord level in a "patch"

26

How is varicella-zoster virus diagnosed?

-clinical symptoms
-Tzanck smear (ginat cells)
-VZV antigen
-PCR of CSF [encephalitis]

27

What is the most important anti-viral varicella-zoster virus treatment?

acyclovir

28

What are the prevention mechanisms for varicella-zoster viral infections?

1) vaccines
-varivax (children)
-zostavax (>60 yo)
2) imunoglobulin

29

How does cytomegalovirus interact with the immune system?

generally immune-controlled

30

What is the primary infection site and latent infection site of alpha herpesviridae (HHV 5-7)?

HHV-5
primary: leukocytes, lymphocytes, monocytes
latent: monocytes, neutrophils, vascular endothelial cells

HHV-6
primary: T-cells
latent: T-cells, monocytes, macrophages

HHV-7
primary: T-cells
latent: CD4+ T-cell

31

How is cytomegalovirus transmitted?

-children, early adults
-infected body fluids
-oral, sexual, vertical transmission
-organ/blood transfusion

32

What is the outcome of a cytomegalovirus infection based on?

immune status of the patient

33

How is a cytomegalosvirus infection diagnosed?

-cytopathic effect (dense, central "owl's eye" basophilic intranuclear inclusion body)
-viral/antigen isolation
-PCR*
-serology, shell viral assay

34

What is the treatment for cytomegalovirus infection?

drug therapy which inhibit DNA replication within the nucleus

35

What are prevention strategies for cytomegalovirus?

-hygenic precautions around children
-safe sex practices
-screen donated blood
-antivirals for transplants