L13- RTI IV Flashcards
Moraxella Cattarhalis:
- Gram(+/-)
- (2) shape
- (aerobic/anaerobic/both)
- oxidase(+/-)
- (non-/motile)
Gram- diplococcus, aerobe, oxidase+, non-motile
what are the common Gram- diplococci
- moraxella cattarhalis
- Neisseria spp.
Moraxella Cattarhalis:
- (1) antibiotic resistance
- (2) colonization factors and location
1- produces β-lactamases –> penicillin resistant
2:
- biofilm formation to colonize URT in children
- colonization is dependent on age and co-morbidities
Moraxella Cattarhalis:
- (1) and (2) are its most prevalent diseases
- (3) are other diseases caused by it
1- otitis media, common cause in children
2- COPD acute axacerbations in elderly
3- sinusitis, pneumonia, bacteremia, periorbital cellulits, conjunctivitis
what will commonly induce COPD exacerbations in the elderly
- Moraxella Cattarhalis
- common cold viruses: rhinovirus, adenovirus, coronavirus
describe pathogenesis of Moraxella Cattarhalis in otitis media
1) colonization of nasopharynx
2) migration from nasopharynx to middle eat via Eustachian tube —- usually precipitated by viral URI
describe pathogenesis of Moraxella Cattarhalis in exacerbation of COPD
1) altered mucociliary function
2) airway colonization and infection
3) triggered by acquisition of new strains –> they dirupt protease - antiprotease balance
Moraxella Cattarhalis: list some of the molecular mechanisms / virulence factors (hint- 6)
- many adhesins for attachment to respiratory epithelium
- intracellular invasion
- complement resistance
- biofilm formation
- induction of inflammation
- acts as a co-pathogen
Moraxella Cattarhalis:
- diagnosis is typically done by (1)
- (2) is suggested, explain process and results
1- clinically, treat empirically
2:
i) Gram stain => Gram- diplococcus –> now must differentiate from Neisseria
ii) chocolate agar: round, opaque colonies with ‘hocky puck’ sign + pink after 48hrs
iii) differentiate from Nesseria: DNase+, Nitrate Reduction+, doesn’t ferment carbohydrates
list the 3 diagnostic differences between Moraxella Cattarhalis and Neisseria spp.
Moraxella Cattarhalis:
1) hockey puck sign (slides like it on agar when touched)
2) DNase+, Nitrate Reduction+
3) doesn’t ferment carbohydrates
Epidemic flu is transmitted from (1) animals via (2) that can survive in the environment for (3). Epidemic flu will last about (4) in a community, where most affected people will be (5).
1- man-to-man
2- respiratory droplets / aerosols
3- ~24hrs (survives drying, depends on humidity)
4- 4-6 wks maximum (rarely lasts longer)
5- recover spontaneous with long-lasting, but weak immunity to particular strain
Flu Symptoms in adults:
- (1) incubation period
- sudden appearance of (2) lasting a few hrs
- (3) symptoms lasting 3-8 days (indicate an important absent symptom)
- (4) recovery days
- (5) contagious days
- (6) highest risk for secondary infections days
1- 1-4 days
2- malaise, HA
3- abrupt rise of fever, chills, severe muscle aches + loss of appetite, non-productive cough (*NO rhinorrhea usually)
4- 7-10 days
5- after 24 hrs for next 7 days
6- 6-12 days post infection
what are the additional symptoms of flu seen in children
- higher fever
- GI Sxs: vomiting, abdominal pain
- earache / otitis media
- muscle pain, sometimes with swelling
- croup often, not always
- febrile convulsions: children under 3, rare occurrence
Influenza virus:
- (1) family
- (non-/enveloped) (linear, circular, segmented) (+/-) sense (ss/ds)(DNA/RNA)
- (7) site of viral replication
1- orthomyxoviridae
enveloped, segemented (-) sense ssRNA
7- replicates in host cell nucleus
describe the structural differences of the influenza subtypes
(classification based on matrix and nucleoproteins)
A- 8 ssRNA segments, subtypes based on surface glycoproteins: hemagglutinin (H), neuramidase (N)
B- 8 ssRNA segments
C- 7 ssRNA segments
on a influenza A virus:
- (1) function of HA protein
- (2) functions of NA protein
- (3) is the target for drug therapy
1- hemagglutinin, attachment and RNA entry into host cell
2- neuramidase, releases sialic groups from membrane glycoproteins –> release of virus from host cell + assists in viral replication + assists in penetration of tissue
3- M2 protein, ion channel (+ NA protein)
Influenza A:
- primary disease of (1) animals
- also infects (2) animals
- (3) current subtypes found in humans
1- birds
2- humans + mammals
3- H1N1, H3N2
Influenza B:
- primary disease of (1) animals
- (2) is more evident than in A strain
- (3) is less evident than in A strain
1- humans (and seals)
2- inc morbidity and mortality (worse complications)
3- dec in epidemics (has never caused pandemic)
Influenza C:
- primary disease of (1) animals
- (2) type illness in humans
- (3) is less evident than in A and B strains
1- humans
2- milder illness than A/B
3- doesn’t cause epidemics or pandemics
In influenza A, 25% of the viral proteins are (1). (2) are the antibody targets generated by the body, although they develop in (3) fashion.
1- HA
2- HA, NA
3- separately; Ab for specific H subtype doesn’t help fight against other H subtypes or any N subtypes
Influenza B:
- (1) and (2) are the lineages
- has the ability to cause the following critical complications, (3)
1- Victoria-like
2- Yamagata-like
3- fulminant disease (acute liver failure) and Reye syndrome (hepatic / cerebral swelling) –> resulting in fatal illness
discuss the transfer of Influenza A between animals
Reservoir- wild ducks / sea birds (mild GI infection, usually asymptomatic in birds)
–> domestic ducks
domestic ducks:
1) –> directly to humans –> farm animals (pig, chicken)
2) –> another farm animal (pig, chicken) –> humans
Pigs are the ‘mixing bowl’ for other strains
describe the Nomenclature for influenza strains [normally on seen on vaccines]
Type / host of origin, A type / geographic origin / strain number / year of isolation + (H#N#, A type)
eg. A/avian/hong kong/06/68 (H3N2)
eg. B/kansas/236/76
For influenza infections, (1) precipitates the local effects and (2) causes the systemic effects. The result of (1), puts the person at risk for (3).
1- epithelial damage including ciliated mucus-secreting cells
2- IFN, CKs via NK cells and T cells
3- bacterial super-infection (loss of natural barriers + exposed binding sites on epithelium)
Influenza virus uses (1) to attach to respiratory epithelium. Then it is taken into the cell via (2) process. The virus then needs (3) protein in order for (4) to occur and release virus into the cytoplasm. Genomic replication occurs in the (cytoplasm/nucleus) and (6) is crucial for cell lysis and the release of virus.
1- HA, hemagglutinin (attaches to sialyloligosaccharide)
2- receptor mediated endocytosis
3- M2 (A strain only, drug target)
4- acidification and envelope fusion –> viral genome released
5- nucleus
6- NA, neuramidase
define Antigenic Drift, relate it to influenza
(seen in A and B strains, sometimes C strain)
- gradual accumulation of Point Mutations => loss of stereospecificity if Ag-Ab bond
- most significantly changes seen in the HA and NA surface proteins
define Antigenic Shift, relate it to influenza
(only seen in A strain)
- sudden rearrangement / reassortment of the 8 segments of the viral genome
- usually from a co-infection of different influenza strains in a single intermediate host
- only seen in A strain b/c its the only strain that infects other animals
Antigenic Drift for influenza virus:
- (gradual/sudden)
- (major/minor) effect on H and N
- affects (H/N > H/N)
- (4) type of genomic change seen
- (5) affected strains
1- gradual 2- minor effect 3- H > N 4- point/single mutations 5- A, B, less frequently C
Antigenic Shift for influenza virus:
- (gradual/sudden)
- (major/minor) effect on H and N
- affects (H/N > H/N)
- (4) type of genomic change seen
- (5) affected strains
1- sudden 2- major effect 3- N > H 4- reassortment of genomic segments 5- A only (B, C don't have intermediate hosts)
list the laboratory tests that can be used to diagnose Influenza
1) Molecular assays, inpatient / high risk patients:
- conventional RT-PCR, multiplex PCR
- rapid molecular tests
2) Ag detection assays, outpatient screening test
3) rarely- viral culture (mostly public health), serology testing
list the 2 major groups of Flu treatments (include target, affected strain)
Amantadine, Rimantidine- M2 protein in A strains only –> prevents uncoating of virus
Tamiflu (Zanamivir, Oseltamivir): NA protein in A and B strains only –> prevents cell lysis / viral release
Amantidine and Rimantidine function and MOA
- targets M2 (ion channel) in A strains of the flu
- inhibits the uncoating of endocytosed viruses
NO effect on B, C strains
Zanamivir and Oseltamivir function and MOA
(Tamiflu)
- inhibits NA
- causes virus to bind to own sialic acid –> forms clumps –> blocks viral release from host cells
- useful for A, B strains
- NO effect on C stains b/c only has 7 segments, no HA, NA present
Influenza A:
- (1) severity on a relative 1-4 scale
- (Y/N) animal reservoir
- (Y/N) pandemics
- (Y/N) epidemics
- Antigenic (Shift/Drift/both)
1- 4 (most severe) 2- yes 3- yes 4- yes 5- both shift and drift
Influenza B:
- (1) severity on a 1-4 scale
- (Y/N) animal reservoir
- (Y/N) pandemics
- (Y/N) epidemics
- Antigenic (Shift/Drift/both)
1- 2 (middle severity) 2- no 3- no 4- yes 5- antigenic drift only
Influenza C:
- (1) severity on a 1-4 scale
- (Y/N) animal reservoir
- (Y/N) pandemics
- (Y/N) epidemics
- Antigenic (Shift/Drift/both)
1- 1 (least severe) 2- no 3- no 4- no 5- antigenic drift only (not often though)
