Types Of Bacteria (+infectious Diseases) Flashcards by Mackenzie Hopkins

2 type of clinical human specimens (in regards to microbiology)

•sterile body site
•sites with commensal bacteria

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Sterile body site meaning

•naturally should not contain any bacteria

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Sterile body site examples

•CSF
•blood and bone marrow
•lower respiratory
•bladder

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Examples of commensal bacteria sites

•upper respiratory (mouth, nose)
•skin
•urethra

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Gram positive result?

Blue/purple stain

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Gram negative result?

Red/dark pink

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What do gram positive bacteria contain

• 1 cell membrane
• thick peptidoglycan
• teichoic acid
• lipoteichoic acid

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What do gram negative bacteria contain

•2 cell membrane (peptidoglycan between)
•thinner peptidoglycan
•LPS layer
•lipoproteins

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Gram positive cocci

•staphylococcus
•streptococcus
•enterococcus

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Staphylococcus description

•Cluster/grape bunches
•gram positive

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2 types of staphylococcus

•coagulase positive
•coagulase negative

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Coagulase positive staphylococcus and function

•staphylococcus aureus
•commensal but highly pathogenic
•most virulent staphylococcus
•recurrent if not treated

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Coagulase negative staphylococcus and function

•staphylococcus epidermidis
•opportunistic low grade pathogen
•usually on biomaterial (implants)

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Streptococci description

•live on skins nose and mouth
•chains or diplococci

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Group A streptococcus description

•gram positive
•long chains

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What cause group A streptococcus cause

•tonsillitis
•necrotising fasciitis
•cellulitis
•skin and soft tissue infection
•scarlet fever

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Streptococcus pneumoniae description

•gram positive
•diplococci

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Enetrococci description

•gram positive
•short chains

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Where is enterococcus most commonly found

•bowel flora

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What can enterococcus cause

•UTI infections
•abdominal sepsis

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Examples of gram negative coccus bacteria

•neisseria meningitis
•neisseria gonorrheae

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Gram positive bacilli bacteria examples

•mycobacterium tuberculosis
•clostridioides difficile

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Examples of gram negative bacilli bacteria

•enetrobacterales
•pseudomonas aeruginosa

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Enterobacterales examples

•Escherichia Coli
•klebsiella sp

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Where are enterobacterales commonly found

•bowel flora

What can enterobacterales cause

•UTI •abdominal sepsis (perforated appendix)

Gram negative environmental opportunists

•pseudomonas aeruginosa •acinetobacter sp

Pseudomonas aeruginosa description

•gram negative •rod bacillus •thrives in damp areas •opportunistic pathogen

What does neisseria mean in terms of shape and gram testing

•coccus shape •gram negative

Neisseria bacteria examples

•N. Meningitidis •N. Gonorrhoeae

What does Neisseria Meningitidis cause

•meningitis •sepsis

Skin and soft tissue infections examples

•cellulitis •wound infections •abscesses

What bacteria cause skin and soft tissue infections

•staphylococcus •streptococcus

What bacteria cause bowel related infections (abdominal sepsis)

•enterobacterales •enterococci •anaerobes

How are many bowel related infections caused

•appendicitis •bowel perforation

Anaerobic bacteria examples

•all of clostridium genus •example = clostridium difficile

Clostridium bacteria description

•endospore forming •anaerobic •gram positive •rod bacillus

Clostridium difficile infections caused

•antibiotic associated diarrhoea •pseudomembranous colitis

What is colitis

•Inflammation of the colon •causes diarrhoea, anal bleeding

What is a UTI caused by

•usually bowel organisms; •E.coli, klebsiella, proteus (enterobacterales) •enterococci

2 types of pneumonia

•community acquired •hospital acquired

What most commonly causes community acquired pneumonia (CAP)

•streptococcus pneumoniae

What bacteria causes hospital acquired pneumonia (HAP)

•resistant strains enetrobacterales •resistant strains S.aureus (MRSA) •environmental opportunistic pseudomonas aeruginosa

What is resistant strains of S.Aureus called and what can it cause

•MRSA •hospital acquired pneumonia

Specific bacteria which are likely culprits of skin and soft tissue infections

•staphylococcus aureus •group A streptococcus

How many s.aureus produce pvl toxin

•<5% of isolated strains •20% in soft tissue injections

PVL toxin mechanism

•pore forming cytotoxic •induced lyses of host cells

What does high PVL cause

•necrosis/cytolysis •degranulation + ROS + inflammation mediators causes macrophage recruitment

What are ROS

Reactive oxygen species

What does low levels of PVL cause

•apoptosis •pore formation of mitochondria

How many s aureus produce exfoliative toxins

Around 5%

Exfoliative toxins mechanism

•hydrolyse desmosome protein in skin •causes loss of keratinocytes •loss of cell adhesions •causes peeling of skin and blisters

What is scaled skin syndrome caused by

•Exfoliative toxins •characterised by blistering and peeling of skin

Bacterial invasion mechanism during impetigo

1- s aureus adhere to skin 2- neutrophil recruitment to epidermis 3- a aureus penetrate following path neutrophil just made 4- blisters expand due to exfoliative toxins cleaving Dsg1

What protein do exfoliative toxins cleave on desmosomes

•Dsg1

Streptococci description

•gram positive •pairs or chains •non motile

Streptococci results from catalase test

•no bubbles •catalase negative

Staphylococci results from catalase test

•bubbles •catalase positive

Streptococci oxygen requirement and nutrient requirements

•mostly facultative anaerobes •complex nutrition requirements

What media should be used for streptococci isolation

•blood •serum enriched

What is browns classification

•hemolytic patterns of streptococcus •alpha, beta or gamma groups

Alpha streptococci visual results

•no yellow ring •green hue colonies

Alpha streptococci haemolytic ability

•partial hemolysis

Alpha streptococci examples

•pneumonia •Viridans sanguis

Beta streptococcus visual results

•yellow ring •clear colonies

Beta streptococcus haemolytic ability

•full hemolysis

Beta streptococcus examples

•pyogenes Group A •agalactiae Group B

What’s are group A streptococcus

Streptococcus Pyogenes bacteria

What are Group B streptococcus

•streptococcus agalactiae

Gamma streptococcus visual results

•no yellow ring •right blue/white colonies

Gamma streptococcus haemolytic ability

•no hemolysis

Streptococcus pyogenes description

•short chains = clinical •long chains = liquid media •1-2mm white colonies

Streptococcus pyogenes skin infections

•impetigo •erysipelas •cellulitis •necrotising fasciitis •ulcers

S. Pyogenes invasions/evasion factors

•secreted proteins •c5a peptidase •streptolysin S •plasminogen binding site

S. Pyogenes adhesion factors

•T protien • F protein •M protien • M like protien

T protein/lipoteichoic acid function

•facilitate binding to host cell

F protein function

•binds to fibronectin on host cell •internalisation