Gram +ve bacteria Flashcards
The thick layer of peptidoglycan contains?
TEICHOICACIDS and lipoteikoic acids
Mycobacterium:
Have _________ a waxy lipid.Protects it from desiccation
mycolic acid
mycolic acid does not stain with water based dyes but with
acid fast stain
What colour doe the gram =ve bacteria stain when it retain the crystal violet dye
Purple
Two major groups slip based on DNA
Low and High G+C bacteria
What are the different shapes of the bacteria
Cocci
Bacilli
Name the three genera of cocci
Streptoccoci
Streptococcus
Enterococcus
The three genera of bacilli
Bacillus
Clostridium
Listeria
Mycoplasmas
Staphylococcus is or is not part of the normal mircobiota ?
It is but can be opportunistic
The arrangement of the Staphylococcus is chain like ?True of false
Its false because they are grape like clustered in arrangement
Three main characteristic of Staphylococcus:
O2;Motility and Tolerant
Facultative-anaerobes
Non-Motile
Salt tolerant on human skin
also to desiccation, radiation and heat
Staphylococcus is catalase +ve or negative?
Positive
Two most common Staphylococcus disease
Staphylococcus aureus and epidermidis
Staphylococcus epidermidis is or is not a part of our normal microbiota
Normal microbiota of human skin and can be opportunistic
What are the 2 mechanical pathogenicity features of staphylococcus ?
Breach skin and only need a few number to enter to cause disease
What are the 3 virulence factors that feature the pathogenicity
ENZYME Production
Toxin
Evade phagocytosis and innate immune résponse.
Staphylococcus pathogenicity:
Structural defenses against phagocytosis
(S. aureus) #Protein-A Binds IgG
#Bound coagulase Fibrin clots hide bacteria from phagocytic cells
What is the common virulent factor between S. epidermidis and S. aureus?
slimelayers-(capsules) for both species S. aureus + S. epidermidis
=Inhibit leukocyte chemotaxis & phagocytosis
= Adhesive properties to surface e.g. catheter, shunts synthetic joints
Name the Staphylococcus enzymes that:
- Digests lipids
- Breaks penicillin and survives β-‐lactam antimicrobial drugs
- lipases
2. β-‐lactamase
Name the 4 main toxins of Staphylococcus virulence.
- Disturbs the cytolitic toxins
- Disrupts desmosomes causing skin to slough off
- Causes Toxic Shock Syndrom
- Enterotoxins- Heat stable and asso. to food poisoning
- Cytolic toxin
- Exfoliative toxin
- Toxic shock syndrome toxin
- Enterotoxin
What is the role of superantigens ?
Cause massive production of cytokins by macrophages and Tcell
Which of the Staphylococcus toxins act as super antigens
Exfoliative toxins, TSST, and Enterotoxin
what bacteria do you commonly find one moist skin folds
Staphylococcus. aureus
gram +ve cocci
Which mucous lining do the Staphylococcus grow in humans?
Upper respiratory tract
GIT
Urogenital tract
Staphylococcus is transmitted via direct contact or via formites
Both
Staphylococcus can be prevented by hand washing ?
Yes aseptic techniques to prevent infection
Staphylococcus bacteria is invasive and proliferates causing
abscesses
& tissue destruction
Non invasive Staphylococcal
Diseases is food poisoning because of ingestion of
enterotoxin-‐contaminated
food
Name the Staphylococcal
cutaneous diseases
Pyogenic lesions
Scaled skin syndrome (toxin)
Staphylococcal scalded skin syndrome features and name the secondary bacterial infection prone from this
Reddening of skin, large blisters wit clear fluid no scarring.
2nd bacterial infection is calle the Ritter disease for neonatal and young children
Pyogenic lesion caused by S. aureus is is characterised by
impetigo and Folliculitis (carbuncle)
Staphylococcal Systemic diseases causes by most of the species
- Bacteremia- 50% are nosocomial infections
- Endocarditis
- Pneumonia
- Osteomyelitis
- Urinary tract infections in young women
Streptococcus is a catalase +ve or -ve?
Catalase Positive
Streptococcus is arranged in cluster ?
No in Pairs and chains
Streptococcus is Lancefield
classified and divided into setotyoes based on ?
Bacteria’s antigen-Group A and B
Lancefield classification results into pathogenic groups namely?
Group A and B
Group A Streptococcus: colonies have large zones of beta-‐hemolysis or alpha-hemolysis … cultured in blood agar plates.
beta-‐hemolysis
What is the differential media used for the diverse streptococcus microorganisms to differentiate the different species?
Blood agar
Streptococcus
pyogenes completely digests blood agar thus they are …… hemolysis
Streptococcus pyogenes are
beta-hemolysis
The differential media used for the Streptococcus
pneumoniae that partially digest blood is -Alpha or Beta hemolysis
Streptococcus pneumoniae partial digests blood: alpha-hemolysis
Enterococcus foecalis does not digest blood agar
Enterococcus foecalis Gamma-hemolysis
Group A Streptococcus:–> Streptococcus pyogenes super antigen is
Pyrogenic or erythrogenic toxins-Acting on macrophages and Tcells= cytokine release to stimulate fever, rash and shock
Streptococcus pyogenes has 7 pathogenicity including the superantigen. 1.How does it evade phagocytosis
- Evades phagocytosis -M protein destabilise complement + HA hides bacteria
Streptococcus pyogenes 1 of 7 pathogenicity is to break down blood clot and increase speed via tissues
Strepokinases
Streptococcus pyogenes 1 of 7 pathogenicity is to reduce pus firmness to facilitate spread
Deoxyribonucleases
Streptococcus pyogenes 1 of 7 pathogenicity is to breakdown complement protein C5a thus decreasing WBC to infection site.
C5a peptidase
Name the streptococcus pyogenes pathogenic the facilitates the spread through tissues.
Hyaluronidase
Name the streptococcus pyogenes pathogenic enzyme that aids in spreading of the bacteria
Hyaluronidase
• Deoxyribonucleases
• Streptokinases
Name the streptococcus pyogenes pathogenicity that lyses RBC +WBC + Platelets
Streptolysins
Streptococcus pyogenes typically infects
Pharynx or skin
how does Streptococcus pyogenes spread ?
Streptococcus pyogenes spreads via respiratory droplets
Group A streptococcal diseases
“strep throat” and “scarlatina” state commonly knows are
Pharyngitis-Inflammation of pharynx
and
scarlet fever-Chest rash
Scarelet fever is a disease of Group A streptococcal diseases caused by what type of toxin?
Scarlet fever streptococcal disease caused by pyrogenic toxins
Which one of the Group A streptococcal diseases is contagious Pyoderma or erysipelas?
Pyoderma- Pus producing lesion because of DC or contaminated fomites
Which one of the Group A streptococcal diseases is the inflammation of lymph nodes Pyoderma or erysipelas?
Erysipelas-Typically seen on children face
Most well known streptococcal diseases called “ flesh eating” group A streptococcal pyrogens
Necrotizing fasciitis- spread along fascia and secrete enzymes and toxins to destroy tissue.
One of the two Group A streptococcal nonsuppurative diseases characterised by complication of untreated streptococcal pharyngitis and autoimmune response against heart antigens?
Group A streptococcal nonsuppurative disease- Rheumatic fever
One of the two Group A streptococcal nonsuppurative diseases characterised by antibody-bound streptococcal antigens that accumulate in the glomeruli of kidney.
Group A streptococcal nonsuppurative disease is- Glomerulonephritis.
Adults may suffer from irreversible kidney damage.
Can you perform a rapid skin test to diagnose Group A streptococcal infection
Yes, rapid skin test used to diagnose respiratory infections group A streptococcal antigens.
Is the the group B streptococcus cocci arrangement in pairs or chains
Chains
Can we distinguish group A from B group:
A) Bigger zone of beta hemolysis
B) specific polysaccharides cell wall antigen
C) Not resistant to bacitracin
B) specific polysaccharides cell wall antigen is what disguises Streptococcal Group A from B
Group B Streptococcus-Streptococcus
agalactiae pathogenicity often infects new borns without the antigen. True or false ?
True:Group B Streptococcus-Streptococcus
agalactiae pathogenicity often infects new borns without the antigen.
Group B Streptococcus agalactiae infection’s for most adults is often a result of?
Wound infections and childbirth
It is true that Group B Streptococcus agalactiae disease is associated with neonatal bacterimia, meningitis and penirmonia ?
YTrue
Group B Streptococcus agalactiae disease is associated with neonatal bacterimia, meningitis and penirmonia ?
Group B Streptococcus agalactiae disease risk group are the immunocompromised patients?
Older immunocompromised patients are at risk
True or false:
Group B Streptococcus agalactiae disease- puerperal
fever (postpartum endometritis)
True:Group B Streptococcus agalactiae disease- puerperal
fever (postpartum endometritis)
