Gram +ive Bacteria Flashcards
resistant to heat and drying
darkly stained
Facultative anaerobic
Staphylococcus
The major component of the S. aureus cell wall
Protein A
(Binds to fc region in IgG , as a result escape from antibody mediated killing)
A basic component of Staphylococcus aureus, Promote binding to mucosal cell of host
FnBP (Fibronectin-binding protein)
a superantigen causes Staphylococcal Scalded Skin Syndrome in children.
What is its name and where can be found
Exfoliating toxin
In Staphylococcus aureus
Where Staph. aureus colonize
In Pharynx, other skin surfaces
Types of infections in Staph. aureus
With 3 ex for each type
1- Superficial and deep infections :
-skin infection(Folliculitis), -Respiratory tract infections
-Urinary tract infections
2- Toxin mediated infections :
-Food Poisoning
-Staphylococcal Scalded Skin Syndrome (SSSS)
- Non coagulase producing bacteria residing on skin as normal flora
associated with biofilms around the implants
sensitive to novobiocin
Staph. epidermis
Non coagulase, frequently causing of cystitis in women
Staph. saprophyticus
colonize the oropharynx of healthy
Asymptomatic
Streptococcus pyogens
What is clinical manifestation of Streptococcus pyogens
Suppurative infections
divided to :
- Respiratory Tract Infections
- Skin and soft tissue Infections
-
Non suppurative complications \
Acute Glomerulonephritis (AGN) , Acute rheumatic fever (ARF)
Tonsillitis and Pharyngitis are systemic Respiratory Tract Infections
✔️or✖️
✖️
Localized
Scarlet fever is Systemic Respiratory Infections
Erysipelas, Pyoderma are
Is Suppurative Skin Infections
صنفي Cytolytic exotoxins
Which is for Staphylococcus and which is for streptococcus
Hemolysins, Streptolysin O and S
Streptolysin for streptococcus
Hemolysins for Staphylococcus
Recount the virulent factors of staphylococcus
1- cell wall (that have capsule-inhibit phagocytosis- , FnBP , protein A)
2- Cytolytic exotoxins : hemolysins (attack RBCs )
3- Enzymes (sush as coagulase , catalase)
For ex. Hyaluronidase, Fibrinolysin
4- superantigens (such as exfoliating toxin , sock syndrome toxin)
5- Enterotoxins (Ingestion of food contaminated with Enterotoxins cause food poisoning within 1-6 hours.)
What is the treatment of Streptococcus
1- Penicillin
2- in Penicillin allergy , Erythromycin or oral Cephalosporin
Antibiotics have no effect on AGN and ARF
✔️or✖️
✔️
What are the 3 virulence factors of Streptococcus
1- Cell wall (a.Capsule-inhibit phagocytosis ,, b. Fimbriae-help in adhesion, made of M protein)
2- Ctyolytic exotoxins (Streptolysin O and S)
3- Enzymes (a. Hyaluronidase ,, b. Streptodornases-which degrade the DNA in necrotising tissue-
,, c. Streptokinase-cause lyses of clot)
Diphtheria is
acute respiratory or cutaneous disease
Explain the steps of Diphtheria Pathogenicity
1-Spread by respiratory droplets from asymptomatic carriers
2-Colonize in tonsils (upper respiratory tract)
3-Multiply and produce toxin
Diphtheria exotoxin (Polypeptide) composed of two fragments, A and B.
Fragment A binds to susceptible cell membranes and helps to enter fragment B into cell.
✔️ or✖️
✖️
The opposite
- localized on throat,
- forms pseudomembrane by grayish thick adherent exudate
are clinical features of ….
Respiratory Diphtheria
Isolation of organism using Tinsdale’s agar (media containing potassium tellurite)
Is lab diagnosis of
Diphtheria
Pulmonary Anthrax is 100% fatal
✔️
Papule develops into Slow-healing painless ulcer covered with black eschar surrounded by edema
Are clinical feature of
Gram +ive Rod Spore forming
(Bacillus)
Reservoir : Soil , Honey , canned meat foods .
Clostridium botulinum
The virulent factor of Clostridium perfringens
Is two types of toxins
Recount them with their functions
Major toxins (alpha toxin) called -lecithinase
lyse mammalian cells
Minor toxins (micro toxin) called -hyaluronidase
lyse the hyaluronic acids of the ECM
Non-Spore forming bacilli
Facultative Intracellular bacteria
can grow at 4 °C
Listeria monocytogens
Pharyngitis , Low grade fever , Cervical lymphadenopathy(Bull neck)
are clinical signs of
Respiratory Diphtheria
How can Cutaneous Diphtheria invade host cell
From puncture wound or cut in the skin
result in introduction of C. diphtheriae
leading to a chronic, nonhealing ulcer
Listeria monocytogens transmitted by
Ingestion of food /Water contaminated
immunogenic precipitation reaction.
For detection of toxin production
Is a lab diagnosis for
Diphtheria
Doxycycline(tetracycline) and fluoroquinolones
Are useful treatment for
+ive Sporing Bacillus
The Pathogenesis of Listeria monocytogens is
1- enter the cell by phagocytosis
2- produce Listeriolysin (to damage phagolysme)
3- produce phospholipase (to rupture the cell membrane and attack neighboring cell)
bacilli producing spores
Thermophilic
Can grow at extremes of acidity & alkalinity (pH 2 to 10)
Bacillus
Obligate anaerobic (Its vegetative cells killed by oxygen)
Most are opportunistic soil saprophytes
Clostridium
Spores germinate during Anaerobic conditions and produce the botulin toxin
Is virulent factor of…
Clostridium botulinum
Source : from contaminated soil
Exudates are profuse and foul smelling
Are characteristic of
Clostridium perfringens
List the Pathogenesis of Bacillus
1- bacteria from soil enter human cells via inhalation, abrasion , ingestion
2- phagocytosed by macrophage in blood
3- multiply inside macrophages and **destroy ** macrophages
4- enter blood circulation
5- specticemia
6- death
Fermentation of carbohydrates yields gas
and its accumulation in subcutaneous tissues crinkling sensation on palpation (crepitations)…..Gas gangrene.
Clostridium perfringens
Mode of action of botulin toxin
(Pathogenesis of Clostridium botulinum)
1- Entry into body via ingestion
2- Absorption into circulation
3- Binds to Ach receptors
4- Flaccid paralysis
Hyperimmune human globulin
Teatnus toxoid injection
Metronidazole
Spasmolytic drugs (diazepam),
The treatment of ….
Clostridium perfringens
Treatment of Listeria monocytogens
Penicillin either alone
or in combination with trimethoprim + sulfamethoxazole.
pseudomembranes are composed of
- Bacteria
- Inflammatory products
- Fibrin
- Cell debris from mucosa
A nthrax toxic complex made up of three subunits
Oedema factor (OF ) - causes elevation of intracellular cAMP. This leads to severe edema
Protective antigen (PA) - It mediates cellular entry of Edema factor and Lethal toxin.
Lethal factor (LF-) - This is responsible for Tissue necrosis
The prevention of Clostridium perfringens bacteria :
proper wound cleansing
Prophylaxis & treatment of Clostridium botulinum
Proper canning & preservation of food
Antitoxin - Intra Muscular
Meningoencephalitis is disease caused by
Listeria monocytogens
