Bacteria Flashcards by Baron HO

What is the infection chain consists of

Host
–> Reservior
–> port of Exit
–> Mode of transport
–> Port of Entry
–> Suspectible Host

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Name 4 pathogenic mechanism

Direct invasion into host, multiplication and damage

Production of toxin

Immunopathology

Oncogenesis

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What does the outcome of host-pathogen interaction is dependent on?

characteristics of both the pathogen and the host

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What does the cytoplasm of a bacteria includes

Nucleoid, plasmids, Ribosomes

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What is covering the cytoplasm and what is outside of the stuff aforementioned

Cytoplasmic membrane
Cell Wall

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What can be outside of the cell wall

Capsule, Pili/ Fimbriae, fragella, etc

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What is pili for

Fragella

For Attachment and transfer of Plasmid

For motility

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What is the component of cell wall

Peptidoglycan

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What is endospore for

It is present in mainly what type of bacteria

What do we do the remove them

What is their appearance under Gram stain

Adapting to environment as it is resistant to heat, radiation and chemicals

Gram-positive bacteria

Wash hand with soap

Empty cell

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What is the structural difference betweeen gram positive and gram niggative bacteria which contributes to the colour change in the result for Gram test

The thickness of peptidoglycan cell wall
Gram positive has thicker cell wall hence can hold more stain to appear violet

While gram niggative bacteria has thinner cell wall after washed by alcohol which degrade the outer membrane hence holds less gram stain and holds the counter stain to appear pink

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Name a structure unqiue for gram niggative bacteria

What is it made of

Why does it bring clinical complications

Outer membrane

Lipid, polysaccharide, lipoprotein, lipopolysaccharide

It reduce the permeability of cell wall to antibiotics

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How do we classify bacteria according to their oxygen requirement

Strictly aerobic (Must have oxygen)

Facultatively anaerobic (Mainly use aerobic respiration, but can use anaerobic respiration if needed)

Strictly anaerobic (Must have no oxygen)

Microaerophilic (Need low Oxygen and elevated CO2)

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For gram positive bacteria

How do we describe if it is spherical shape

How do we describe if it is spore forming rod

How do we describe if the balls are diploid

How do we describe if the balls are in chain

How do we describe if the balls are in 4

How do we describe if the balls have a lot of them

Coccus

Bacillus

diplococci

streptococcus

Tetrad

Cluster

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What is the test to different among coccus bacterium

What is the positive result

What is the name of the bacteria which gives positive result

What is the name of bacteria which gives negative result

Catalase test

Formation of Colourless gas bubbles when mixed with Hydrogen peroxide

Staphylococcus

Streptococcus

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How to differentiate among staphylococcus bacterium

What are the 2 types of the test.
What are they reacting with to form what
What are the pros and cons

What is the positive result

What is the bacteria giving Positive result

What is the bacteria giving negative result

Coagulase test

Slide test
Fibrinogen to form fibril
Quick (~10s), but can give false negative

Tube test
prothrombin
Definitive, but takes up to 24 hours

Formation of any clot

Staphylococci aureus

Staphylococci Epidermidis
Staphylococci Saprophyticus

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What is S. epidermidis

Part of the normal human microbiota, typically the skin microbiota (commensal / normal flora).
*
Adheres to prosthetic devices, e.g., implants, catheters.
*
Causes prosthesis-associated infections.

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What is the clinical complication of S. saprophyticus

Acute Cystitis in young woman

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What is the appearance of S aureus under Blood agar

What is responsible for the colour

What is it’s function

Golden yellow colonies

Staphyloxanthin

Protect it toxic oxygen radicals

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What aids S aureus for

Attachment

Evasion of host defense

Invasion

Toxins

Teichoic acid

Protein A, catalase, coagulase

Protease, hydluronidase, lipase, DNase

Haemolysins
Epidermolytics toxins
Toxic Shock Syndrome Toxins
Enterotoxins
Panton-Valentine leucocidin

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What does Protein A of S aureus

inhibits opsonophagocytosis and induces B cell death

** Opsonophagocytosis= Phagocytosis of pathogens opsonized with antibodies and/or complement proteins.

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What does

Haemolytic toxins (also name what type is it)

Toxic shock Syndrome toxin

Enterotoxins

Panton-Valentine leucocidin

Cause

Damage erythrocytes lymphocytes, monocytes (α-haemolysin)

staphylococcal scalded (燙傷） skin syndrome

staphylococcal toxic shock syndrome

Food poisoning

Dermonecrosis (necrosis of skin)

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What is the

Reservior

Transmission

Risk factor for Staphylococcus aureus

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Human (30% healthy people are carrier)

Direct contact

Risk factors:
Increasing age.
Male sex.
Alcoholism.
Hospitalisation.
Diabetes mellitus.
Dialysis.
Intravenous drug use.

What does the word pyogenic mean

What are the Pyogenic symptoms caused by Staphylococcus aureus

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Forming Pus

Skin and soft tissue infections.
Surgical site infections.
Osteomyelitis, septic arthritis.
Pneumonia.
Infective endocarditis.

What are the toxin-mediated symptoms of Staphylococcus aureus

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Staphylococcal scalded skin syndrome.
Staphylococcal toxic shock syndrome.
Food poisoning.

What are the examples of Skin and soft tissue infections caused by Staphylococcus aureus

Folliculitis: inflamed hair follicles. Furuncles: skin abscesses involving the hair follicles and surrounding tissue. Carbuncles: coalescing clusters of furuncles, deeper suppuration and scarring In short Folliculitis= infection of follicle Furuncle=deeper infection Carbuncle: >1 Furuncle

What are the antibiotics that can work on Staphylococcus aureus (and the population which are resistant to the antibiotic) Mark the one which most population are resistant to it. And the enzyme involved

Penicillin (90% of A aureus) [penicillinase] Vancomycin (Vancomycin-resistant S. aureus, VRSA) Penicillinase-stable penicillin: methicillin, cloxacillin (Methicillin-resistant S. aureus ,MRSA)

For streptococci, what are their Appearance Diameter OXygen requirement Are they encapsulated Spore-forming?

Gram-positive cocci in chains or in pairs. 0.5-1.2 μm in diameter. Facultatively anaerobic, some requires CO2 for growth. Some species are encapsulated. Non-spore-forming.

How do we classify streptococci according to their haemolytic activity

α-haemolyticstreptococci (partially haemolytic) β -haemolytic streptococci (fully haemolytic) non-haemolytic streptococci

How do we further classify β -haemolytic streptococci

By Lancefield Grouping

Name the 2 β -haemolytic streptococci and their result under Lancefield Grouping

Streptococci pyogenes (GAS) Streptococci agalactiae (GBS)

What can GAS cause

Acute tonsillopharyngitis (扁桃體炎) Acute skin and soft tissue infections Invasive GAS disease Streptococcal toxic shock syndrome Scarlet fever (猩紅熱) Acute rheumatic fever (風溼熱 ) Post-streptococcal glomerulonephritis (急性增殖性腎小球腎炎)

What can GBS cause

Neonatal sepsis (blood infection in infant >90 days old) Various invasive infections

Name an a-haemolytic streptococci

S. pneumoniae

What will Streptococci pneumoniae cause

Pneumococcal pneumonia Invasive pneumococcal disease

Name 5 Gram positive Bacilli

Listeria monocytogenes, Corynebacterium diphtheriae, Bacillus anthracis, Nocardia, Clostridium

For gram-negative bacteria, what domain of their outermembrane is most bioactive. What component of it is used to as endotoxin What is the antigen on the fimbriae

Lipid A domain Lipopolysaccharide

What is the natural habitat And Antigens of Enterobacterales

Most are commensals in the large bowel of human and animals O antigen: Somatic LPS antigen H antigen: Flagellar antigen K antigen: Capsular antigen

Name 4 examples under enterbacterales

Escherichia Coli Klebsiella spp. Salmonella spp. Shigella spp.

Name 2 Examples of escherichia Coli that cause Diahorrhoeal disease Name 4 examples of disease that is extraintestinal disease

Enterotoxigenic E. coli (ETEC) → traveller’s diarrhoea Enterohaemorrhagic E. coli (EHEC)/shiga toxin-producing E. coli (STEC) → haemorrhagic colitis, haemolytic uraemia syndrome. urinary tract infection, bacteraemia, (bacteria in blood) meningitis in neonates, (neonate= baby< 4weeks, meningitis=腦膜炎) peritonitis (腹膜炎)

Name an example of Salmonella Bacteria Is Salmonela Oxidase positive or niggative How can we distinguish the serotypes Name a clinical significance of the whole family What can cause typhoid and parathyphoid fever How do we call those which can cause Disseminated/focal infections

Salmonella Enterica Different O and H antigen composition It is an important cause of food poisoning Salmonella enterica serotypes Typhi + Paratyphi A, B, C. Non-typhoidal salmonellae.

Name 2 non-fermentors

Pseudomonas aeruginosa Burkholderia pseudomallei

What is the Shape of the non-fermentors Oxygen requirement? Are they resistant to antibiotics? Why are they called non-fermentators

Bacilli (rod-shape) Strictly aerobic Very resistant They do not ferment glucose

What is the result of Pseudomonas aeruginosa in Oxidase test Colour? Any smell? What does it cause What is the clinical complication it cause that has high mortality What is the mortality for the aforementioned clinical complication

Positive Green Fruity Hospital-acquired infections Neutropenic septicaemia (a whole-body reaction to an infection) 50%

What does Burkholderia pseudomallei cause What is the place in which there are endemic

Melioidosis Southeast Asia and northern Australia; also in China, the Indian subcontinent.

What is the incubation period of Burkholderia pseudomallei

Incubation period 1-21 days (mean, 9 days).

What is Burkholderia cepacia complex Do they exhibit positive or nigative result in catalase test What are the clinical disease caused How is it antibiotic resistivity

a species complex consisting of Burkholderia cepacia and at least 20 different biochemically similar species of Gram-negative bacteria. Positive Respiratory tract colonisation/infection in patients with cystic fibrosis. Nosocomial infections Often resistant to multiple classes of antibiotics

For Neisseria Are they What shape? Gram positive or niggative What is their result in oxidase test Name 2 species of Neisseria

Dicoccus Niggative Positive N. gonorrhoeae (gonococci) N. meningitidis (meningococci).

What is the function of the pili/fimbriae of the Neisseria As well as the capsule Name an endotoxin and what's its function

Pili/fimbriae: Attachment Capsule: Anti-phagocytic Lipo-oligosaccharide. As endotoxin and important in adherence, colonisation and activation of immune cell

What is the reservior and transmission for Neisseria gonorrhoeae What does it cause in men What does it cause in women Extra-genital infection? What are the disseminated gonococcal infection Name a clinical disease that happens when it infects an infant of 1st month old

Reservior: Human. By sexual contact and muscosal contact Urethritis Endocervicitis. Pelvic inflammatory disease Proctitis Pharyngitis Infective endocarditis Septic Arthritis Meningitis Gonococcal ophthalmia neonatorum

What agar do we use for Neisseria gonorrhoeae Does it develop Antitbiotic resistance

Thayer-Martin Agar (improved chocolate agar) Yes

For Neisseria Meningitidis What is the reservior Transmission One can be carrying the bacteria without having symptoms, how are they called What clinical disease can it cause What are the 3 types of vaccines

Humans Respiratory droplets, direct mucosal contact Asymptomatic carriage Invasive meningococcal disease: * Meningitis. * Septicaemia (bacteria in blood that cause immune overreaction) * Purulent conjunctivitis. * Meningococcal pneumonia. * Polysaccharide vaccine. * Quadrivalent conjugate vaccine. * Serogroup B protein-based vaccine

What can charcoal do in the recovery of Bordetella species

Remove the toxins that may be present in the swab or specimen that inhibit the growth of Brodetella Species

What genus of bacteria cause Cholera Does all species of it cause cholera What is the test result for oxidase Appearance? Is it motile? Where is it present What can it cause

Vibrio No Positive Curved bacilli Yes Natural water bodies including sea and fresh water Gastrointestinal tract infection and severe systemic infection

What can Shigella cause What are the 4 species What is the toxin and what is it's function

bacillary dysentery S. dysenteriae, S. flexneri, S. boydii, S. sonnei Inhibits eukaryotic protein synthesis, eventually leading to host cell death.

Bacteria Flashcards

(54 cards)