gram psitive cocci

8/18/2019 GRAM Psitive Cocci

1/12

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VE COCCI +GRAM

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2/12



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. Staphylococcus SPP

Cocci. -Gram +ve

Catalse +Ve

arranged in cluster of grapes

-most staphylococcus Non motile. Non sopre.

-most staphylococcus facultative anerobic.

-able to grow in media containing high concentration of salt.

-at temp from 18C-40C staph bacteria are present on the skin andmucous membrane of human.

-Opportunistic infections.

the outer layer of most staphylococcus cell wall covered with

(polysaccharide capsule).

-Eleven capsular serotypes have been identified in S.aureus with

serotypes 5 and 7 associated with majority of infection.

-peptidoglycan can form Half the cell wall of staph.

protin A can be used as specific identification test for S.aureus( not

other Non coagulase staph)

-There are simple biochemical tests e.g (coagulase, protein A ,

heat- stable nuclease , manitol fermentation) can be used to identify

colonies ofS. Aureus and other staph.




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Staphylococcus aureus

* cause most Staphylococcal diseases .* Gr + Ve Cocci .

* Non Sporing , Non Motile Cocci

*Usually has capsulate .(polysaccharide)&slim layer.

* Facultative anaerobic .haracteristics

* Humans ( nose , skin , mucous ) .

* Always present in hospital environment .

* Survives drying . Tolerant of SaltsHabitat

* Direct contact .

* Airborne route .Transmission

*Capsule= inhibits chemotaxis and phagocytosis.

And facilitates adherence to foreign bodies.

*Peptidoglycan= inhibits phagocytosis.* Hemolysins = lyse RBCs

* Coagulase = converts fibrinogen to fibrin(clots plasma)*catalase= remove of hydrogen peroxide.

* Fibrinolysin = Digest fibrin* Leucocidin = kills leukocytes

* DNase = hydrolyses DNA

* Protein A = Antiphagocytosis (inhibits antibody

clearance) and anticomplementary.

* Enterotoxin = Vomiting & diarrhea

* TSS toxin-1 = produce leakage or destruction ofendothelial cells.

* Exfoliative Toxin = Skin exfoliative

Pathogenesis

* Superficial infection(scalded skin syndrome) ( SSS )

* Surgical Wound Infection

* Toxic Shock Syndrome . (( TSS ))* Toxic Food Poisoning . (( TFP ))

* Septicemia , Endocarditis , pneumonia .Diseases

* White or Golden Colonies on Blood Agar

* Catalase +Ve , Coagulase +Ve , DNase + VeLaboratory

Identification




4/12



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Staphylococcus epidermidis

* Rarely cause infections in health people .

* Gr + Ve Cocci .


*Opportunistic pathogen.

* Facultative anaerobic .

*Slime layer.

haracteristics

* Humans (skin) .* Always present in hospital environment .

* Survives drying . Tolerant of SaltsHabitat

* Direct contactTransmission

* Lower pathogenicity than Staph. Aureus .

* Viscous extracellular slime = Enable the bacteria to

adhere to a foreign surface .

Pathogenesis

* Urinary Tract Infection ( UTI )* Prosthetic valve Endocarditis.

*Bacteremia.*surgical wounds.

*central nervous system infection.

Diseases

* White Colonies on Blood Agar

* Catalase +Ve , Coagulase -Ve , DNase - Ve

* Sensitive to Novobiocin disc .Laboratory

Identification




5/12



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Staphylococcus saprophyticus

* Gr + Ve Cocci .


* Facultative anaerobic .haracteristics

* Skin

* Genitourinary mucosa .Habitat

* Direct contact

* Endogenous spread to urinary tract .Transmission

* Virulance factors unknown

* But , this bacteria has ability to colonize periurethral

skin & mucosa .

Pathogenesis

* Urinary Tract Infection ( UTI ): opportunistic infection.Diseases

* White Colonies on Blood Agar

* Catalase +Ve , Coagulase -Ve , DNase - Ve

* Resistance to Novobiocin disc .Laboratory

Identification




6/12



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Streptococcus SPP

- Gram +ve cocci

-catalase –ve.-arranged in pairs or chains.

-most streptococcus facultative anaerobic.

-some grow only in atmosphere enhanced with carbon

dioxide(capnophilic growth).

-carbohydrates are fermented, resulting in the production of lactic acid.- most B-hemolytic streptococcus have group –specific antigen.

-most (but not all) alpha-hemolytic streptococcus and nonhemolytic

streptococcus (gamma) do not have the group –specific antigen.

)arylamidase-B- pyrrolindonyl-L(PYR-

if positive(Streptococcus pyogenes) or negative (Streptococcus

anginosus)

for rheumatic fever or acuteuseful confirming testASO tests-

glomerulonephritis caused BY Streptococcus pyogenes.

Classification of Common Streptococcal Pathogens

Biochemical

Classification Serologic Classification Hemolysis Patterns

S. pyogenes A β

S. agalactiae B β; occasionally nonhemolytic

S. dysgalactiae C, G β

S. anginosus group A, C, F, G,

nongroupable

β; occasionally α or

nonhemolytic

S. bovis D α; nonhemolytic; occasionally β

Viridans group Nongroupable α or nonhemolytic

S. pneumoniae

Enterococci

Nongroupable

D

Α

α – β or Gamma




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Biochemical Identification of Common Streptococci

Organism Susceptibility

Hippuratehydrolysis

CAMPreaction

Bilesolubility

Bacitracin Optochin

S. pyogenes* S R - - -

S. agalactiae R R + + -

S. anginosus† R R - - -

S.

dysgalactiae‡

R R - - -

S. pneumoniae R S - - +

Viridans group R R - - -

S= Sensitive

R= Resistant




8/12



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Streptococcus pyogenes

Group A , B hemolytic streptococcus )

* Gr + Ve cocci in chain .

* Non Sporing , Non Motile Cocci .

* Some strains produce a hyaluronic acid capsule .* Facultative anaerobic .*Growth is optimal on enriched-blood agar media.

*inhibited if the medium contain high conc.of glucose.*the basic structural cell wall is peptidoglycan.

haracteristics

* Commensal in the throat or skin

Habitat

Direct contact

Airborne routeTransmission

M Protein = Antiphagocytosis[ Major Virulence Factor ]*T protein= unknown function.

*capsule=Antiphagocytosis.

Hemolysins = lyse RBCs.

Erythrogenic toxins = cause fever & rash in scarlet

fever

Streptokinase = lyses Blood clot .

DNAse = hydrolyses DNA .

NADase = Kills Leucocytes .

Pathogenesis

Pharyngitis , Tonsilitist , Otitist media .

Erysipelae & lampotigo .

Scarlet Fever .

Rheumatic Fever .(ASO confirming test)

Endocarditis .

Diseases

White small colonies on blood agar .

Colonies surrounded by Beta Hemolysis.

Catalase –Ve Bacitracin Sensitive

PYR +Ve.

Laboratory

Identification




9/12



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Streptococcus agalactiae

Group B , Beta hemolysis Streptococcus ))

* Gr + Ve cocci in chain .* Non Sporing , Non Motile Cocci .

* Facultative anaerobic .*capsule(polysaccharide)

*the surface protein (C protein)

haracteristics

* Normal Vaginal ( 25% ) & Oral flora .

Habitat

* Direct ContactTransmission

* Virulance factors not clearly Identified .* Capsule is major virulence factor if it is present

.=Antiphagocytosis .Pathogenesis

Neonatal Meningitis .

Septicaemia

Septic abortion .

Pneumonia.Diseases

Colonies on blood agar larger than S.pyogenes .

The colonies are buttery a narrow zone of B-

hemolytic.

Colonies surrounded by Beta Hemolysis.

Catalase –Ve

Bacitracin Sensitive .

CAMP test +Ve

Hippurate hydrolysis +Ve.

Laboratory

Identification




10/12



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Streptococcus pneumonia

Alpha H emolytic Sterptococcus ))

Commonest pathogen cause pneumonia .

Lancet shape. Gr + Ve Diplococci

* Non Sporing , Non Motile Cocci .

Ploysaccharide capsule .

Facultative anaerobic .

Major cell wall structure is peptidoglycan (like allgram-positive cocci).

The other major cell wall component is teichoic acid.

haracteristics

* Commensal in Human Respiratory Tract .

Habitat

* Droplet spread .

Transmission

* Capsule = Antiphagocytosis .

Pathogenesis

Pneumonia .

Septicemia .(Bactermia)

Meningitis ( Children less than 3 years & adults 45

years and above ))

Otitis Media .

Diseases


Colonies surrounded by Alpha Hemolysis.

Can grow only on enriched media.

Can ferment several carbohydrates.(lactic acid)

Grow poorly in media with high glucoseconcentration.

Catalase –Ve

Optichin Sensitive . Bile solubility Sensitive.

Laboratory

Identification




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Streptococcus viridans

Alpha Hemolytic Sterptococcus ))

Gr + Ve cocci

Non Sporing , Non Motile Cocci .

Facultative anaerobic .

Do not have group-specific.haracteristics

Commensal in the human upper respiratory tract .

Large Number are found in Oral Cavity .

Rarely found in skin because fatty acid in skin aretoxic to them

Habitat

Droplet Spread .Transmission

Attachment to tooth enamel & gums via various

carbohydrates is important in establishment thecolonization .

Ability to produce acid cause ---} Dental caries .Pathogenesis

Dental caries .

Bacterial endocarditis (( Bacteria enter the blood

stream as result of dental manipulation and attach todamaged cardic valves .

Intraabdominal infections.

Diseases


Produce green pigments on blood agar. Colonies surrounded by Alpha Hemolysis.

Catalase –Ve .

Optichin Resistant .

Laboratory

Identification




12/12



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VE COCCI +GRAM

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Medical Microbiology

لف مل ل Patrick Murray

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gram psitive cocci

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