Module 1-4

What is the shape and Gram reaction of Staphylococcus?

Perfectly spherical Gram (+) cocci

How do Staphylococcus bacteria grow?

In clusters like a bunch of grapes

What are the two pigmented colony types of Staphylococcus?

S. aureus - golden yellow and S. epidermidis - white

Where is S. aureus commonly found?

Nasal passages, skin, oral cavity, and intestinal tract

Where is S. epidermidis commonly found?

On the skin

What surface proteins promote colonization in Staphylococcus?

Fibronectin,Fibrinogen/fibrin binding (clumping factor),Collagen-binding factor

It is Present on epithelial and endothelial surfaces and as a component of blood clots.

Fibronectin

What is the function of fibrinogen binding in Staphylococcus attachment?

Promotes attachment to blood clots and traumatized tissues

What is a major factor in Staphylococcus infections related to medical devices?

Biofilm formation on implanted materials

True or false?

If material is in the body for long periods, fibrinogen is degraded and no longer promote bacterial attachment

True

True or false?

Fibronectin becomes less predominant ligand promoting attachment.

False,They become more predominant

What are the two factors that inhibit phagocytosis in Staphylococcus?

Capsule and Protein A

What is do you called the capsule of Staphylococcus?

Capsular polysaccharide

What is the main function of Protein A in S. aureus?

Binds IgG the wrong way

What toxin specifically acts on polymorphonuclear leukocytes?

Leukocidin

It is Responsible for symptoms during infections and Membrane damaging toxins

Protein Toxins

What is the most potent membrane-damaging toxin in Staphylococcus?

Alpha-toxin

True or false?

Human platelets and monocytes have high affinity to toxin.

True

(A-toxin) A complex series of secondary reactions cause release of ________ and ________ which trigger the production of inflammatory.

eicosanoids and Cytokines

What is the main function of Beta-toxin?

Damages membranes rich in sphingomyelin

Classical test is the lysis of ___________, at 4’C-15’C produces incomplete hot-cold lysis

sheep RBC

What does Delta-toxin act as?

A phospholipase

Small peptide toxin produced by most strains of S. aureus

Delta-toxin

What do Gamma-toxin and leucocidin do?

Damage membranes of susceptible cells

What are the three proteins expressed by Gamma-toxin and leucocidin?

B and C proteins.

Which combination of proteins is hemolytic and weakly leukotoxic?

A and B proteins.

How does Panton-Valentine (PV) leucocidin differ from other leukotoxins?

PV leucocidin has potent leukotoxicity but is non-hemolytic.

What genetic locus differentiates PV leucocidin from other leukotoxins?

The gamma locus.

What are the two major superantigens in Staphylococcus?

Enterotoxins,TSST-1

What does enterotoxin cause?

Diarrhea and vomiting (staphylococcal food poisoning)

What is TSST-1 responsible for?

Toxic Shock Syndrome (TSS)

What toxin causes scalded skin syndrome in neonates?

Epidermolytic (exfoliative) toxin (ET)

What are the two forms of Epidermolytic toxin?

ETA and ETB

It is the possibly the toxin targets a specific protein involved in maintaining the integrity of the epidermis and do Protease activity?

Epidermolytic (exfoliative) toxin (ET)

What is the function of coagulase in S. aureus?

Binds prothrombin to form staphylothrombin leading to fibrin clot formation

What is the traditional marker for identifying Staphylococcus aureus?

Coagulase

What is the function of staphylokinase?

Activates plasmin-like proteolytic activity to dissolve fibrin clots

It acts as Plasminogen activator and Complex formed between staphylokinase and plasminogen

Staphylokinase

What is the role of staphylothrombin in the coagulation process?

It activates the protease activity of thrombin, leading to the conversion of fibrinogen to fibrin and clot formation.

What are three important enzymes in Staphylococcus virulence?

Proteases, Lipases,DNase

What is the function of fatty acid modifying enzyme (FAME)?

Modifies antibacterial lipids to prolong bacterial survival

What is the function of hyaluronidase?

Hydrolyzes hyaluronic acid (cementing substance)

What is the most important coagulase-negative Staphylococcus?

S. epidermidis

What infections are commonly caused by S. epidermidis?

Infections associated with prosthetic devices and catheters

What is the characteristic of S. epidermidis biofilm?

Produces slime (biofilm)

How does S. aureus differ from S. epidermidis in fermentation?

S. aureus ferments mannitol

What is a common habitat for S. intermedius?

Dogs and carnivores

What disease does S. hyicus cause in swine?

Exudative epidermitis

What disease does S. aureus cause in horses?

Botryomycosis

What disease does S. aureus cause in cattle?

Mastitis

What disease does S. aureus cause in lambs?

Tick pyemia

What disease does S. aureus cause in turkeys?

Purulent synovitis (Bumblefoot)

What disease does S. aureus cause in rabbits?

Cutaneous staphylococcosis

What is the main disease caused by S. epidermidis?

Opportunistic infections in prosthetic devices

What disease is caused by Staphylococcus hyicus subsp. hyicus in swine?

Exudative epidermitis (greasy pig disease).

What is the main species affected by Staphylococcus hyicus subsp. hyicus?

Swine (pigs).

What nutrient is required for the growth of Staphylococcus hyicus subsp. hyicus?

Biotin.

What are the five main diagnostic tests for Staphylococcus?

Smears,Blood Agar Plate (BAP),Mannitol Salt Agar (MSA),Coagulase Test,DNase Test

What does the Coagulase Test differentiate?

S. aureus (coagulase +)

What does Mannitol Salt Agar differentiate?

S. aureus (mannitol fermenter) and S. epidermidis (non-fermenter)

Why is there no effective vaccine for Staphylococcus infections?

Due to high antigenic variability and immune evasion mechanisms

What are the two main mechanisms of antimicrobial resistance in Staphylococcus?

Beta-lactamase production,Methicillin-resistant S. aureus (MRSA)

What is the significance of MRSA?

It exhibits multiple-drug resistance and is difficult to treat

What is the shape and arrangement of Streptococcus?

Non-motile, non-sporeforming coccus in pairs or chains

Does Streptococcus produce catalase?

Catalase (-)

What is the oxygen requirement of Streptococcus?

Facultative anaerobe

Where is Streptococcus commonly found?

Mucous membranes, intestines, milk

Who proposed the classification of Streptococcus?

Sherman

What are the four major groups of Streptococcus based on their characteristics?

Pyogenic, Viridans, Lactic, and Enterococcus.

What does the term 'Viridans' refer to in Viridans streptococci?

It refers to the greenish (alpha) hemolysis they produce on blood agar.

What are the four groups in Sherman’s classification?

Pyogenic, Viridans, Lactic, Enterococcus

Which Streptococcus group is primarily associated with milk and dairy products?

Lactic group.

Which group of Streptococcus primarily affects the intestines?

Enterococcus group.

What is the basis of Lancefield classification?

Serologically active carbohydrate (C substance)

How many groups are in Lancefield classification?

Six main groups (A, B, C, D, E, N) plus 14 additional groups

Where is the carbohydrate antigen found in Streptococcus?

Cell wall or between cell wall and membrane (teichoic acid)

What is required for Streptococcus growth fast?

Enrichment with blood and serum

How do Streptococcus colonies appear?

Small, delicate, translucent colonies

What substance does Streptococcus produce in milk?

Lactic acid

What is the function of the hyaluronic acid capsule?

Interferes with phagocytosis

What is the role of Protein M?

Responsible for virulence and inhibits phagocytosis

It is a type-specific immunity,inhibits phagocytosis, immunotoxic effect on polymorphs and platelets

Protein M

What structure helps Streptococcus attach to epithelial cells?

Lipoteichoic acid in hair-like fimbriae

Which hemolysins are produced by Streptococcus?

Streptolysin O and Streptolysin S

Which Streptolysin is oxygen-sensitive and elicits neutralizing antibodies?

Streptolysin O

Which Streptolysin is Oxygen-stable, non-antigenic?

Streptolysin S

What is the function of Streptokinase?

Activates plasminogen to plasmin, digesting fibrin clots

What is the function of DNases (A, B, C, D)?

extracellular enzymes, reduce viscosity of pus by degrading DNA

What is the role of Hyaluronidase?

Promotes spread of infection in tissues

It is responsible for rashes in scarlet fever

Erythrogenic toxin A

What does NADase do?

Kills phagocytes

What is the function of Proteinase?

Broad substrate specificity produced by Group A streptococci

What test identifies S. agalactiae?

CAMP test

What is the characteristic color of Streptococcus agalactiae growth on a solid medium containing starch?

Brick red

What is the habitat of S. agalactiae?

Mammary glands of cows, sheep, and goats

How is S. agalactiae spread?

Milker’s hands, contaminated machines, calf mouths

What is a key symptom of S. agalactiae infection?

Inflammation and fibrosis in mammary glands

True or false

Milk becomes alkaline, because WBC count exceeds 500,000/ml, milk reduced, thin, and watery by S. agalactiae

True

What disease does S. dysgalactiae cause?

Acute severe mastitis

What Lancefield group does S. dysgalactiae belong to?

Group C