Microbiology 2: Community and hospital aquired infection Flashcards
What are common virulence factors? Exemples
Factors that contribute to barterial infetions
Flagella-mobility
Pili-adherence
capsule-protect from phago-strep pneumoniae
Endospores-dormant forms-very resistant-C.Diff
Biolfilms-aggregated in polysaccharide matrix-abx resistant-pseudomonas aeru, staph epidermidid
What are the some forms of exotoxins in bacteria?
Exotoxins-
neurotoxin-Botulimun
Enterotoxins-Infection diarrhoae-need live bacteria-(Cholera/E.Coli) or food poisoning (GI infection-no need live bacteria at any moment) (bacillius cerus)
Pyrogenic-stimulate release of cytokines-staph aureus
Tissue invasive-enzymes that can destroy tissue, DNA, fibrin, RBC, etc=staph aureu, strep Pyo
misc exotxons
What are endotoxins? What are the some forms of endotoxins in bacteria?
Endotoxins-only found in Gram - bacteria
Its the the LPS layer-kipid A moeity LPS
shed in stready amount from bacteria
but after death (like treatment) -mass release of the LPS can cause toxic shock/sepsis
What is the definition of an outbreak?
A greater than normal/expected number infected and diganosed with a particular infection in a given period of time
Need good diagnostic techniques, good surveillance (to know whats normal)
need lab isolation of the bacteria causing it with the right genes
Epidiemological criterias
outbreak in 2011 of enteroagregative E.coli (EAEC)-Abx resistance andcauses heamolytic aneamia
What is heamolytic uremic syndrome?
Acute renal feature and heamolytic aneamia and thrombocytopenia
Usually caused by Shiga Toxin producing E.Coli-EHEC (enterohemmorghaic E.coli)
Reservoir: cattle
human infection usually comes from ingestion of faeces
how can strains harmless E.coli forms outbreaks? eg EAEC
Normally, strains of bacteria wont randomly cause outbreaks
usually phage transfer of some genes to another
in 2011, combination of the shiga toxin strain and a plasmid with AAF (adherens fimbrae caused a more agressive, more resistance e.coli strain that could colonise new areas)
These genes are usually on highly mobile genetic elements-easy horizontal transfer
what does the shiga toxin do?
Genes coding for:
StxA/B subunits-StxA enzymatically domain
StxB-pentaer responsible for binding ribosomes
->shut down ribosome activity
What changes where bacteria can colonise?
usually the virulance factors decide where bacteria can grow
in EAEC-could grow in large and small intestine. Normal Shiga toxin strains cant grow in large-made is specifically more dangerous and agressive
Adherence fimbrae-encode for AAF on plasmid-adhesion to enterocytes
name 3 virulance factors and name their function?
Flagellum, adherence, capsule, biofilm, spores, exotoxins, endotoxins
What are 5 important respiratory tract infection in europe?
influenza, animal influenza, sars, legionnairs disease (gram - bacteria)
tuberculosis (mycobateria tuberculosis
What is legnionella pneumophillia)
gram-
normally in ameaba in ponds but can reach air conditioning
Inhalation lead to infection of alveolar macrophages-grow
But human is dead end
How does legionella infect humans?
needs t4SS sectretions systems on surface that helps injects toxins within the macrophages, causing them to phagocytose them-in the vacuoles they grow replicate tgen exit
What is mycobacteria tuberculosis?
Gram + bacteria
very weird cell wall-has extra lipid layer making treatment gard
can becomes latent bewteen unfection
Abx courses take nearly 6 months and sucess only 2/3
And second infections tend to be resistant
What are some exemples of Sexually transmitted unfection?
Chlamydia (clamydia trachomatis), Gonorrhoae (neissrias gonorrhoae, Hep B, Hep C, HIV, aids, Syphilis (trepanenoma pallidum)
What is Chlamydia Trachomadis?
Most common STI cause in Europe–obligate intracellular pathigen
can cause very severe eye infection=3% of worlds blindness
What is Neiseria gonorrhoae?
gram - diplodoccuss
Infection initate in urogenital by interating with non cilliated cells
has pilli and angitenic variation
Escade detect and avoid clearance
Exemple of food and water born disease/
way too many salmonella, anthrax, botulism, Campylobacter, lysteria, cholera, shigella
What is campylobacter -especiolly C. Jejuni
most common GI injectious disease (need live organism)
cases sporratic
Mostly infect small children–undercooked poulty
Virulence factor
T4SS, toxins, adhesion factors, flagella
What is salmonella sp?
Very common Gi infection-undercooker poulty
usually outbreaks-again small children
use a type 3 Secretion system–inject toxic proteins into target cells
What is vibrio Cholerae?
Acute, severe diarhhoae-death if water not given
Usually in outbreak forms
Water born
Virulence factor-type IV fibrea Cholera toxin (initiatlly carried on phages)- cause cells to produce signalling molecules opening Cl channels out-and water follows
What is lysterioa monocytogenes
Risk in immunocompromised, elderly and pregnant (and fetus)
Found in cheese and crosses intersine, blood, fetal barrier
can enter in cells, and spread from cell to cell using their ActA
Exemples of emerging and vector born disease?
Malaria, plague (Yesnerinia pestis), Q fever (coxiella burnetti), SARS, smallpox, West nile virus, yellow fever
Exemple of vaccine preventable disease?
Diptheria, heamophilius inluenzae, nesseirssa meningitides, strep pneuniae, bordetella pertussis, tetanus
vaccination has worked amazingly well, especially on smallpox and polio, measle, rubella, mumps
in bacteria, diphteria,
What is antimicrbial vs antibiotic?
antimicrobial-against microbes-indiscrimiate
Abx-against bacteria specific
abx is form of antimicrobial
What is a health care associated infection?
Infection that occurs after exposure to healthcare
starts more than 48h after admission (before could be due to other things)
very large numbers in EU get it a year-40000 die from it
Most frequent from surgery sties, UTI, pneunoniae, GI, bloodstream, skin
Why are hospitals sources of infections?
lot of infectious agents around-hygenes not always perfect
patients tend to be immunocompromised-higher chance
higher chance of broken skin/wound
catheters, central lines
also just more concentrated amount of sick
What are the main pathogens that cause hospital infection?
ESCAPE- Enterococcis feacis (gram + Staph aureus (gram + C.Diff Gram + Acinetobacterer, baumanii (gram - Pseudomonas aergun (-) Enterobacteria (ecoli, klebstriella,etc )(gra -
Why are the escape pathogens problems?
The pathogens tend to be have Abx resistance-most are only resistant to one form of Abx (like MRSA-methicillin resistant)
But some are just highly resistant to all-Acenitobacter baumanii
also the Abx clears gut microbacteria-and then C.diff which isnt affected-> gets advantage
What is pathogenic E.coli? what Abx to use against them
Most common community and hospital UTI
Large amount of multi resistant strains-evem up to 3rd generation (cephalosporins-b-lactam-prevent peptidoglycan synthesis-and only kill bacteria-20% resistance)
Produce mobile plasmid extended spectrum b lactamases-> cleaves cephalosporin
Still sensitive to carbapenems (B lactam-but not targetted by extended B lactamase. resistance with enzyme carbapenamase)
What are cephalosporins and carbapenes? How resistant ?
cephalosporins-b-lactam-prevent peptidoglycan synthesis-and only kill bacteria-20% resistance)
Produce mobile plasmid extended spectrum b lactamases-> cleaves cephalosporin
Still sensitive to carbapenems (B lactam-but not targetted by extended B lactamase. resistance with enzyme carbapenamase)
What is klebstriella pneumoniae? and pseudonomas>
Cause UTI and Resp infection
Immunocompromised
resistant to 3rd generation-cephalosporins, fluroquinolone, aminoglycosides
also carbapanem resistant
pseudomonas-also ummino compromise and high resustant
What is S aureus?
most important cause of infection world wild
MRSA-methicillin resistance
also a B lacctam-inhbit peptidoglycan wall synthesis
resistance from extra penicillin-binding-protein that can make cell wall–> can synthesise peptidoglycan and survive in presence of methicillin
What is enterococcus Faecium?
Vancomycin resistant
Third highest cause of nosocomial infection
target peptidoglycan syntesis as well (but not like B lactams)
resistance comes from production ofdifferent subtrated vancomycin doesnt bind
