Gram +ive Bacteria Flashcards by Maisaa Ebrahiim

resistant to heat and drying

darkly stained

Facultative anaerobic

Staphylococcus

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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)

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A basic component of Staphylococcus aureus, Promote binding to mucosal cell of host

FnBP (Fibronectin-binding protein)

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a superantigen causes Staphylococcal Scalded Skin Syndrome in children.

What is its name and where can be found

Exfoliating toxin
In Staphylococcus aureus

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Where Staph. aureus colonize

In Pharynx, other skin surfaces

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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)

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Non coagulase producing bacteria residing on skin as normal flora

associated with biofilms around the implants

sensitive to novobiocin

Staph. epidermis

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Non coagulase, frequently causing of cystitis in women

Staph. saprophyticus

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colonize the oropharynx of healthy

Asymptomatic

Streptococcus pyogens

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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)

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Tonsillitis and Pharyngitis are systemic Respiratory Tract Infections
✔️or✖️

✖️
Localized

Scarlet fever is Systemic Respiratory Infections

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Erysipelas, Pyoderma are

Is Suppurative Skin Infections

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صنفي Cytolytic exotoxins
Which is for Staphylococcus and which is for streptococcus

Hemolysins, Streptolysin O and S

Streptolysin for streptococcus

Hemolysins for Staphylococcus

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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.)

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What is the treatment of Streptococcus

1- Penicillin
2- in Penicillin allergy , Erythromycin or oral Cephalosporin

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Antibiotics have no effect on AGN and ARF
✔️or✖️

✔️

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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)

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Diphtheria is

acute respiratory or cutaneous disease

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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