Ability to cause disease - production of toxins - Enzymes that influence host function - Interfere with host normal function - complete immune invastion

Microbiology Flashcards by Jule Hoelscher

Forms of Bacteria

Coccus

Bacillus

Sprirlli

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Gram Positive Bacteria (reason, examples)

Staphylococcus aureus

Streptococcus pneumoniae

Streptococcus pyogenes

One Cell membrane+ thick Cell wall –> peptidoglycans in Cell wall keep colour of gram stain

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Gramm Negative

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Gram Negative bacterias examples

E-coli

Salmonella

Shigella

Vibro cholerae

Neisseria

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Which steps are required for bacterias to cause illness?

Colonize
Persist –> immune response, physical etc.
Replicate –> nutrients required
Spread
Cause Disease –> Produce toxins, affect immune respone, induce diorhe

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Extracellular Pathogens

predominanatly outside of cells

Staphylococcus

Strptococcus

Yersinia

Neisseria

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Intracellular Pathogens

Mainly inside of cell

Can:

Escape in Cell (Listeria Shigella)

Prevent fusion with lysosomes (Salmonella, Mycrobacteria)

Fusion with lysosomes and formation of pagolysosome (Coxiella)

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Horizontal Bacterial DNA exchange:

Transformation: DNA uptake of free DNA

Conjugation: Sharing of plasmid ring throuhg mating bridge

Transduction: uptake of bacterial DNA through Phage (Virus) and further spread

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A Pathogenicity Island

DNA fragment that contributes to disease

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Injectiosome

Action fragment that sticks out of bacteria, used to be injected in cells –> modification of Actin filament –> engulfment

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Flagella

“Tail” of bacteria

Actin fillament

Used fo movement

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Bacterial Infectivity

General stragegie which help to cause infection (–> direct effect on infectious dose)

Transmission

Colonization

Tropism Finding unique niche

Replication

Avoid immune defence of host

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Bacterial Virulence

Ability to cause disease

production of toxins
Enzymes that influence host function
Interfere with host normal function
complete immune invastion

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Infective dose

Number of bacteria which can cause disease (dependant on Infectivity)

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Potential sources

Intrinsic (self infection)

Extrinsic (environment)

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Possible routs of bacterial infections

Upper respiratory trackt –> Upper respiratory trackt infection, lower rewpiratory trackt infection, Spread to adjacent tissues (e.g. ear, brain,) –> Spread to bloodstram

Urogenital trackt –> Bloodstream and/or Pregnancy, Baby (genital)

Broken skin

Gastro-intestinal trackt

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Neisseria

Gram negative

Meningititis (Neisseria meningitidis (Meningokokken)–> Tröpfcheninfetktionen

Neisseria Gonorrhoeae ( cause Tripper) –> sexuell übertragbar

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Haemophilus influenzae

Gram negative

bacillus

Tröpfcheninfektion

Mainly symptoms in upper respiratory trackt

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Escherichia coli

Gram negative

Sources of bacterial infection

Intrinsc (any non-sterile site of body)

Extrinsic (outside world)

Expected vs unexpected portals of entry

Expected: Harmless bacterial via expected route

Unexpected: Harmless via unexpected route or pathogenic bacteria via any route

Possible routes of infection : Upper respiratory trackt + examples

Upper respiratory trackt –> adjacent tissue /lower respiratory trackt

Bloodstream

Mouth: e.g. streptococcus pyogenes –> Tonsilitis

Neisseria meningitidis –> Meningococcal septicemis

Upper respiratory: S. pneumonia/pneumonia

Possible routes of infection: Urogenital trackt

Urinatry infection –> Bloodstream

Genital –>( pregnangy related) 1.GBS/neonatal meningitis).–> Bloodstream

Possible routes of infection : broken skin

selbsterklärend

e.g. staph. A.

streptococcus pyogens

Possible routes of infection: GI examples

Cholera

Commensals

Bacterial that do not cause disease

Infectivity

"Infectious dose" --\> how much needed to cause disease * Transmission * Colonisation * Tropism– Find unique niche (in or outside cells) * Replication Immune Evasion

Virulence

Enhances disease causation: Toxin Production, Enzyme secretion, interfere with normal host, immune supression

Salmonella sp.

Gram negative causes GI infection

Vibrio cholerae

GI infection Gram - rice water stool (NA and CL) ioons

Shigella

Gramm -, rods infection of epithelia in stomach --\> diarreah

Staph. A

Gram + causes many infections

Reason for high rates of HAI

- many sick people at one place (spread + aquire easily) - use of antibiotics

Antibiotic: Aminoglycosides

integrate wrong / not functinoal AA in proteins (target Ribosomes) --\> membrane damage, proofreading

Antibiotics: Rifampicin

targets RNA polymerase subunit --\> prevents transcription

Antibiotics: Vancomycin

cell membrane synthesis

Antibiotics: Linezalid

bind to 50S ribosomal Subunit, prevent protein synthesis

Antibiotic: Daptomycin

Bacterial cell membrane

Selective Toxycity

Antibiotics target many different bacterial processes

Why resistance higher morbidity, mortality and cost

Longer time til effective treatment additional treatments (e.g. surgery) required new, expensive drugs more toxic or less effective drugs

Mechanisms of drug resistance

1. change targeted site 2. inactivation (e.g. enzymatic degradation) 3. Alternative metabolic pathway (inhibited process not required, overexpression --\> enough to survive) 4. Decrease drug accumulation (don't let drug in, pump it out)

Nature of viruses

Intracellular, obligate pathogens small (20-200nm) genetic and structural diverse

Enveloped viruses

enveoped by lipid of host cell membrane can be any shape

Capsid viruses

Non enveloped (protein capsule)

Virus classification

Baltimore classification system: Single, double stranded, positive negatvie sense (negative = complementary to DNA), RNA, DNA viruses etc. --\> way of genome replication within cell