Practical 3

• Gram staining

Differential staining

• Acceptance of stains is an important

property of bacteria and is the base

divission of bacteria to 2 principal groups

Gram positive and Gram negative in

taxonomy. • Gram staining

GRAM STAINING PROCEDURE • Prepare a heat fixed smear of the culture you

wish to examine

• Flood the smear with crystal violet (30 sec. to 2 min)

• Quickly and gently wash off excess stain (2 seconds)

• Flood the smear with Grams iodine (1 minute)

• Decolorize with alcohol (10-20 seconds or until the excess alcohol which flow off the slide is colorless)

• Quickly and gently wash off excess stain (2 seconds)

• Flood the smear with safranin (carbolfuchsin) (30 sec to 2 min.)

• Quickly and gently wash off excess stain (2 seconds)

• Blot dry with bibulous paper

• Examine your slide under the microscope. Record sketches of the organisms, size, color, morphology, and culture identification.

G+ G-

G+ cocci

G-cocci in pairs - diplococci – N.

gonorrhoeae in and out PMNL

sample of pus from pyogenic artritis

G- rods in and out PMNL –

sample of urene in patient with

cystitis caused by E. coli

Gram stain

1. Staphylococcus epidermidis

2. Moraxella catarhalis

3. E.coli, C.albicans

4. Moraxella catarhalis, Streptococcus pneumoniae

5. B.cereus, E.coli

Praktické cvičenie č. 3

Téma : Farbenie podľa Grama

1. Zhotovte fixovaný preparát z kultúry S.epidermidis, zafarbite podľa

Grama, mikroskopujte.

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2. Zhotovte fixovaný preparát z kultúry Moraxella catarhalis, zafarbite

Gramom, mikroskopujte.

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3. Zhotovte zmiešaný preparát z kultúr E.coli, C.albicans, zafarbite

podľa Grama, mikroskopujte.

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4. Zhotovte zmiešaný preparát z kultúr M. catarhalis, S.pneumoniae,

zafarbite podľa Grama, mikroskopujte.

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5. Zhotovte zmiešaný preparát z kultúr B.cereus a E.coli zafarbite

podľa Grama, mikroskopujte.

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Praktické cvičenie č. 3

Téma : Farbenie podľa Grama

1. Zhotovte fixovaný preparát z kultúry S.epidermidis, zafarbite podľa Grama, mikroskopujte.

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2. Zhotovte fixovaný preparát z kultúry Moraxella catarhalis, zafarbite Gramom,

mikroskopujte.

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3. Zhotovte zmiešaný preparát z kultúr E.coli, C.albicans, zafarbite podľa Grama,

mikroskopujte.

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4. Zhotovte zmiešaný preparát z kultúr M. catarhalis, S.pneumoniae, zafarbite podľa Grama,

mikroskopujte.

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5. Zhotovte zmiešaný preparát z kultúr B.cereus a E.coli zafarbite podľa Grama,

mikroskopujte.

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