Microbiology 2: Community and hospital aquired infection

Question 1

What are common virulence factors? Exemples

Answer 1

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

Question 2

What are the some forms of exotoxins in bacteria?

Answer 2

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

Question 3

What are endotoxins? What are the some forms of endotoxins in bacteria?

Answer 3

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

Question 4

What is the definition of an outbreak?

Answer 4

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

Question 5

What is heamolytic uremic syndrome?

Answer 5

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

Question 6

how can strains harmless E.coli forms outbreaks? eg EAEC

Answer 6

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

Question 7

what does the shiga toxin do?

Answer 7

Genes coding for:
StxA/B subunits-StxA enzymatically domain
StxB-pentaer responsible for binding ribosomes
->shut down ribosome activity

Question 8

What changes where bacteria can colonise?

Answer 8

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

Question 9

name 3 virulance factors and name their function?

Answer 9

Flagellum, adherence, capsule, biofilm, spores, exotoxins, endotoxins

Question 10

What are 5 important respiratory tract infection in europe?

Answer 10

influenza, animal influenza, sars, legionnairs disease (gram - bacteria)
tuberculosis (mycobateria tuberculosis

Question 11

What is legnionella pneumophillia)

Answer 11

gram-
normally in ameaba in ponds but can reach air conditioning
Inhalation lead to infection of alveolar macrophages-grow
But human is dead end

Question 12

How does legionella infect humans?

Answer 12

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

Question 13

What is mycobacteria tuberculosis?

Answer 13

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

Question 14

What are some exemples of Sexually transmitted unfection?

Answer 14

Chlamydia (clamydia trachomatis), Gonorrhoae (neissrias gonorrhoae, Hep B, Hep C, HIV, aids, Syphilis (trepanenoma pallidum)

Question 15

What is Chlamydia Trachomadis?

Answer 15

Most common STI cause in Europe–obligate intracellular pathigen
can cause very severe eye infection=3% of worlds blindness

Question 16

What is Neiseria gonorrhoae?

Answer 16

gram - diplodoccuss
Infection initate in urogenital by interating with non cilliated cells
has pilli and angitenic variation
Escade detect and avoid clearance

Question 17

Exemple of food and water born disease/

Answer 17

way too many salmonella, anthrax, botulism, Campylobacter, lysteria, cholera, shigella

Question 18

What is campylobacter -especiolly C. Jejuni

Answer 18

most common GI injectious disease (need live organism)
cases sporratic
Mostly infect small children–undercooked poulty
Virulence factor
T4SS, toxins, adhesion factors, flagella

Question 19

What is salmonella sp?

Answer 19

Very common Gi infection-undercooker poulty
usually outbreaks-again small children
use a type 3 Secretion system–inject toxic proteins into target cells

Question 20

What is vibrio Cholerae?

Answer 20

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

Question 21

What is lysterioa monocytogenes

Answer 21

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

Question 22

Exemples of emerging and vector born disease?

Answer 22

Malaria, plague (Yesnerinia pestis), Q fever (coxiella burnetti), SARS, smallpox, West nile virus, yellow fever

Question 23

Exemple of vaccine preventable disease?

Answer 23

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,

Question 24

What is antimicrbial vs antibiotic?

Answer 24

antimicrobial-against microbes-indiscrimiate
Abx-against bacteria specific
abx is form of antimicrobial

Question 25

What is a health care associated infection?

Answer 25

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

Question 26

Why are hospitals sources of infections?

Answer 26

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

Question 27

What are the main pathogens that cause hospital infection?

Answer 27

ESCAPE-
Enterococcis feacis (gram +
Staph aureus (gram +
C.Diff Gram +
Acinetobacterer, baumanii (gram -
Pseudomonas aergun (-)
Enterobacteria (ecoli, klebstriella,etc )(gra -

Question 28

Why are the escape pathogens problems?

Answer 28

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

Question 29

What is pathogenic E.coli? what Abx to use against them

Answer 29

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)

Question 30

What are cephalosporins and carbapenes? How resistant ?

Answer 30

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)

Question 31

What is klebstriella pneumoniae? and pseudonomas>

Answer 31

Cause UTI and Resp infection
Immunocompromised
resistant to 3rd generation-cephalosporins, fluroquinolone, aminoglycosides
also carbapanem resistant

pseudomonas-also ummino compromise and high resustant

Question 32

What is S aureus?

Answer 32

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

Question 33

What is enterococcus Faecium?

Answer 33

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