Gram- Rods (Entero)

Question 1

What are some future methods of identification?

Answer 1

• Maldi-TOF
  
  • matrix-assisted laser desorption/ionization – time of flight(smaller molecules will reach detectors quicker compared to larger molecule, this results in figure below in terms of peaks)
• Maldi
  
  • impart a charge to the sample
• TOF
  
  • directly proportional to the mass of the molecule
• Identification within a minute

Question 2

Outline general features of K. Pneumoniae

Answer 2

Klebsiella is a genus of Gram-negative, oxidase-negative, rod-shaped bacteria with a prominent polysaccharide-based capsule. Klebsiella species are found everywhere in nature.

Question 3

Outline the process of K. Pneu infection.

Answer 3

leading cause of nosocmial penomnia and can cause sepsis, normaly found in the gut but can infect other systems such as urinirty/blood stream - thus leading cause of spesis. (nosmicmial menaig hospital obtained which can be caused by the movement of healthcare workers and the infection of immunisupressedvindivuals this chain reaction - think of that video u saw). - you can use this mind map in exam as well!! - mind mapp shit

also hypervirulent strains (due to capusle VF) can now infect generally healthy patients

Question 4

Explain K. Pneu VF and how they help in Pathogenesis.

Answer 4

Capsule; 1. image below shows classical capsule with fimrbair around it alongside lipolysaccagride in contrast to hypersaarchide capsuel which allows prevention ofphagicytosis by immune system as well as other immune components as seen in image.
2. simultaneously its producing a number of siderophores scavamging for iron to allow to component in the infectious process.
3. detection beweetn a normal capusle vs hyper a PCR is conducted on the w2i locus. if w2i is detected = hypercapsule meaning increased virulence is present vs no detection of w2i thus decreased viurlnce within that species.

LPS; 2. LPS is both advantages and disadvantages for the pathogen: DISADV: LPS is easily rexongzued by human immune system and will thus target the pathogen → It is able to activate the host defense system through interaction with Toll-like receptor 4, thus triggering pro-inflammatory mechanisms(see image).
1. if a lot of the cells are lysed within the blodstream the build up of LPS can cause toxi shock syndrome.
3. ADV: LPS provide protection against humoral defences despite its recongtion by immune system. protects against antibiotics - establishes a permeability barrier that protects the cell from the entry of toxic molecules such as antibiotics and bile salts.

Type 1 Fimbriae; 1. fimbriae are small rpotriuson frm the cell and allow pathogen to attach and form a biofilm. this is expression the majority of species/strains within kelbiseall group and is essential to its survival.
2. Fim A helps with bladder cell invasion and biofilm formation on them thus causing a UTI.
3. Fim H is a double edge sword in its advntagsours and siadavntages capabilities, it allows for biofilm formation but also is a signal to neurophils and macripohges that its foreign and icnites an immune response.
4. there’s a number of additional genes that also aid this virulence (Fim D,C, etc)

Type 3 Fimbriae; 1. help in binding to both tissue and abiotic surafeces (microsplastcs, e.g. catheters)
2. same gist as type 1
3. additional genes if knocked out or blocked, we see a determentak ability for this bacteria to perform its function/abilities.

Fimbriae Expression; 1. they are not expressed in early infection and so we know they are not needed for colonization so there is some kind of trigger for expression. we know that fimbraie expression is required for bladder cell invasion and we can see that fimbraise is switched on and priodcued to be able to infect which is not the case in lung and GI tract infection because they’re not specially looking to format a biofil ascoaited with bladder cells.
2. if Fim genes were blocked we see an increase in colonization in areas where kelnseiall wouldn’t be normally found to that extent.

Question 5

Treatments and resistance of K. Pneu.

Answer 5

K. Pneu is very capable of aquiring resistance. To be able to adminster an appropriate treatment, suvalliance must be done in order to ensure that a specific drug or treatment that the pathogen is resistant to is not being given as it wont have any affect. the following are the types of treatments:

Intrinsic resistance
-beta lactaseses(e.g. penicillin)
Sensitive
-cephalosporins

Treatments VS Resistance

• Acquired an extended-spectrum beta-lactamases
  
  • Resistance to carbenicillin, amoxicillin and ceftazidime
• 2009 acquisition carbapenem resistance
  
  • New Delhi metallo-beta-lactamase
• Current usage
  
  • Aminoglycosides and cephalosporins
  • Combination clavulanic acid
  • Colistin
    
    • this is a last resort antibiotic and is a repurosped antibiotic since its disconination back in the 70s but due to AMR its now being used. resistance to thus is also building in klebisella and is spreading between species due to plasmids.

Question 6

Infection process of salmonella.

Question 7

Diagnosis and treatment of salmonella.

Answer 7

Diagnosis;
- Typhoid fever
- Isolation from blood and culture (MacConkey)
- Slide agglutination (antigen test)
- Vi (virulence)
- O (LPS) factor 9
- H (flagellar) factor d
- Detection only positive in 40-60%
- Low cfu per ml blood
- Resistance to antibiotics → Outbreak strain - genotyping → Other detection methods being investigated(e.g. PCR, MALDI-ToF)

Treatment;
Antibiotics & vaccine