specimen Blood Agar Chocolate Agar MacChonkey Agar

Trypticase Soy Agar

E.coli Growth, dry, β hemolysis, rough.

Dry, growth, rough.

Dry, lactose fermented, good growth.

Rough, growth.

Moraxella catarrhalis

Growth, ŷ hemolysis.

Slight growth. No growth because it is fasteduse bacteria.

Slightly growth.

Pseudomonas aeruginosa

Growth, ŷ hemolysis.

Growth, smooth. Growth, rough. Begmantation, growth.

Salamonella species

Growth, ŷ hemolysis.

Growth, smooth. Gram(-), lactose non-fermented bacteria, good growth.

Good growth.

Klebsilla species Growth, ŷ hemolysis, meucoud.

Growth, meucoid

Mecoud, lactose fermented bacteria, growth.

Meucoid, growth.

Staphylococcus aureus

Growth, β hemolysis.

Growth, smooth. No growth because it is gram(+) bacteria

Growth, smooth.

Staphylococcus epidermidis

Growth, ŷ hemolysis.

Growth, smooth. No growth. Growth, smooth.

Streptococcus pyogenes

Growth, β hemolysis.

Slightly growth. No growth. Slightly growth.

Streptococcus viridians

Growth, α hemolysis.

Growth, smooth, green.

No growth. No growth.

Candida albicans Growth, ŷ hemolysis.

Growth, smooth. No growth because it is yeast.

Growth, smooth.

Unknown

Discution:

What is the difference between selective & differential media? Give examples of each?

**selective media:is one that grows only certain microorganisms while inhibiting(or preventing) others from growing,that is to say, the media has certain chemicals that allow one organism to grow but another organism cannot grow with those ingredient in the media, thus, is selective for the organisms that can grow in that media. Therefore, most commonly grows only one type of organism.

>>Example: MacConky Agar, Eosin methylene blue EMB.

**Differential media: is one that distinguishes one microorganism from another, it can grow more than one microorganism, but depending on how each organism reacts to the media(like turns red) it differentiates from another microorganism. In this type of media if you are trying to different reactions to the media, and thru their visible reactions you can tell them apart (differentiate them).

>>Example: Blood Agar, MacConky Agar, EMB.

Which organisms produced pink colonies on MacConky Agar, Explain?

**E.coli, Psuedomonas aeruginosa, Klebsiella pneumonia. (gram(-)) MacConk Agar contains bile salt (to inhibit most Gram (+) bacteria), crystal violet dye (which also inhibits certain gram (+) bacteria), neutral red dye (which stains microbes fermenting lactose), lactose and peptone.

By utilizing the lactose available in the medium, these bacteria will produce acid, which lowers the pH of the agar below 6.8 and results in the appearance of red/pink colonies. The bile salts precipitate in the immediate neighborhood of the colony, causing the medium surrounding the colony to become hazy.

You have incubated some of the plates in a candle jar, explain why?

**The candle jar can be used to decrease the concentration of oxygen in the culture environment. Bacterial plates or tubes are placed in a jar along with a lighted candle. The lid is sealed. As the flame burns, oxgyen decreases and the flame gose out. Oxgyen is present, but at a lower percentage than in the atmosphere. The concentration of carbon dioxde increases as a result of the flame; this is also desirable for many microaerophiles. Which is required for the isolation of certain pathogenic bacteria.

Which is easier? To isolate a pathogen from stool specimen or from CSF specimen & why?

**From CSF,because of the absence of normal flora to screen out and the presence of pathogenic bacteria while stool contains numerous numbers of normal flora.

Discuss different patterns of hemolysis on blood agar?What is producing this hemolysis?

**(α) hemolysis: Incomplete, partial hemolysis of blood agar, the agar under the colony is dark and greenish, caused by hydrogen peroxide produced by the bacterium, oxidizing red hemoglobin to green methoglobin.

**(β) hemolysis: complete hemolysis, complete lysis of cells in the agar, the area lightened yallow and transparent.

**(ŷ) hemolysis: No hemolysis the agar under is unchanged.

From the bacteria you used which one causes: Pharyngitis : Streptococcus pyogenes. Urinary tract infection: Klebslla. Wound and burn infection: Psuedomonus aeruginosa. Blood diarrhea: E.coli. Abscess and skin infection : Staphlucoccus epidermidis. Endocarditis in intravenous drug user : Staphlucoccus epidermidis. Endocarditis after dental extraction : Staphylococcus variadans. Oral or vaginal thrush: Streptococcus mutas, Streptococcus mitis, Streptococcus

salivaris.

AL-Quds UniversityFaculty Of Dentistry

Isolation of Bacteria from (simulated clinical specimens) Streak Plating (Overview of Complex, Selective and Differential Meadia)

Abdullah Hassan 21211003

Sura Barham 21211160

Fakhre Kanaan 21211062

Khaled Abu-Baker