Microbiology Laboratory Turkey

Mikrobiyoloji Ile Ilgili Tüm Konuların Kısa ve Öz Anlatımları. Microbiology Lab Information.

Bu Blogda Ara(SEARCH)

MicroLab

fungi etiketine sahip kayıtlar gösteriliyor. Tüm kayıtları göster
fungi etiketine sahip kayıtlar gösteriliyor. Tüm kayıtları göster

12 Şubat 2019 Salı

Şubat 12, 2019

Candida albicans | Yeast/Fungus

Candida albicans



STRUCTURE AND PHYSIOLOGY
Candida albicans is a diploid, Gram-positive fungus that can take on a unicellular (yeast) or multicellular (hyphae, pseudohyphae) form. A unique characteristic to this microbe is that it can switch between different phenotypes. The change between the two phenotypes can happen multiple times and is spontaneous. Studies show strong evidence that these phenotype switches are due to the change in the control of regulatory gene expression. One phenotype of this microbe is white, round cells in smooth colonies.  The other phenotypic form is opaque, rod-shaped in flat, gray colonies. The two forms have different antigen expression and different affinities for tissues. This evolutionary advantage allows it to be highly adaptive to environmental changes.

TRANSMISSION AND DISEASE
Humans normally share a commensalism relationship with C. albicans, but C. albicans can become pathogenic if a person is immunocompromised or if there is a change in their normal microbiota. C. albicans prefers to invade the skin or mucosae but can also infect the blood, heart, and lungs.


DISINFECTION
Candida albicans can survive for long periods of time without nutrients and is known to form biofilms on medical devices; therefore, disinfection to kill these fungi is very important.
NOTES
C. albicans has been shown to encode the standard Leucine (CUG) codon as serine. As a divergence from the standard genetic code, it is thought to have given the organism an evolutionary advantage driven by selection.
INSTAGRAM
0
By on Hiç yorum yok:
Etiketler: , , , , , , , , , , , ,

2 Şubat 2019 Cumartesi

By on Hiç yorum yok:
Etiketler: , , , , , , , , , , , , , , ,

1 Ekim 2018 Pazartesi

Ekim 01, 2018

UREASE TEST

UREASE TEST

Objective

To determine the ability of the organism to hydrolyse urea by the action of urease enzyme.


Principle

Urea is a nitrogen-containing compound that is produced during decarboxylation of the amino acid arginine in the urea cycle. Urea is a major organic waste product of protein digestion in most vertebrate and is excreted in urine. Some bacteria have the ability to produce an enzyme urease as part of its metabolism to break down urea. The urease is a hydrolytic enzyme which attacks the carbon and nitrogen bond with the liberation of ammonia and carbon dioxide. It is a useful diagnostic test for identifying bacteria, especially to distinguish members of the genus Proteus from Gram-negative pathogens. Proteus vulgaris is an important and fast producer of urease.

Urease test is performed by growing test organism on urea agar slant or urea broth with phenol red as an indicator with pH6.8. During the incubation period, the organism capable of producing urease enzyme hydrolyse urea and produce ammonia that raises the pH level. As the pH increases, the phenol red changes from yellowish orange as the initial colour of medium to deep pink. Failure of development of a pink colouration due to no ammonia production is evidence of an inability of the organism to produce urease enzyme.

Media

Enzymatic digest of gelatin (1 g), dextrose (1 g), NaCl (5 g), KH2PO4 (2 g), urea (20 g), phenol red (0.012 g), per 1000 mL, pH 6.8.

Procedure

  1. Streak the surface of a urea agar slant with a portion of a well-isolated colony or inoculate test organism on urea broth containing phenol red as the indicator.
  2. Incubate the urea agar slant or urea broth at 37°C for 24-48 hours.
  3. Examine the development of pink colour.
  4. In case of unknown result incubate the tube for 7 days to check for slow urease production.

                               
                             

Results

Positive: Deep pink colouration, Light Orange, Magenta

Negative: No Color change, Yellowish orange colouration


Limitations

  1. Some organisms rapidly split urea (Proteus spp, H. pylori), while others react slowly.
  2. Urea Agar should not be used to determine the quantitative rate of urease activity, as organisms vary in their capability and rate of hydrolysis.
  3. Prolonged incubation may cause an alkaline reaction in the medium and give the false positive result.


Quality Control

Positive: Proteus vulgaris (ATCC13315)

Weak positive: Klebsiella pneumoniae (ATCC13883)

Negative: Escherichia coli (ATCC25922)


INSTAGRAM

FACEBOOK

0
By on Hiç yorum yok:
Etiketler: , , , , , , , , , , , , , , ,

26 Eylül 2018 Çarşamba

Eylül 26, 2018

GRAM STAINING

GRAM STAINING

What is Gram Staining?
Gram staining is a common technique used to differentiate two large groups of bacteria based on their different cell wall constituents. The Gram stain procedure distinguishes between Gram positive and Gram negative groups by coloring these cells red or violet. Gram positive bacteria stain violet due to the presence of a thick layer of peptidoglycan in their cell walls, which retains the crystal violet these cells are stained with. Alternatively, Gram negative bacteria stain red, which is attributed to a thinner peptidoglycan wall, which does not retain the crystal violet during the decoloring process.



Gram-staining Procedure

Gram-staining is a four part procedure which uses certain dyes to make a bacterial cell stand out against against its background. The specimen should be mounted and fixed on a slide before you procede to stain it. The reagents you will need to successfully perform this operation are:
  • Crystal Violet (the Primary Stain)
  • Iodine Solution (the Mordant)
  • Decolorizer (ethanol is a good choice)
  • Safranin (the Counterstain)
  • Water (preferably in a squirt bottle)

⧫ Before starting, make sure that all reagents, as well as the squirt-bottle of water, are easily accessible because you won't have time to go get them during the staining procedure. Also, make sure you are doing this near a sink because it can get really messy. Wear a lab coat.

 


STEP 1: Place your slide on a slide holder or a rack. Flood (cover completely) the entire slide with crystal violet. Let the crystal violet stand for about 60 seconds. When the time has elapsed, wash your slide for 5 seconds with water. The specimen should appear blue-violet when observed with the naked eye.

STEP 2: Now, flood your slide with the iodine solution. Let it stand about a minute as well. When time has expired, rinse the slide with water for 5 seconds and immediately procede to step three. At this point, the specimen should still be blue-violet.

STEP 3: This step involves addition of the decolorizer, ethanol. Step 3 is somewhat subjective because using too much decolorizer could result in a false Gram (-) result. Likewise, not using enough decolorizer may yield a false Gram (+) results. To be safe, add the ethanol dropwise until the blue-violet color is no longer emitted from your specimen. As in the previous steps, rinse with the water for 5 seconds.

STEP 4: The final step involves applying the counterstain, safranin. Flood the slide with the dye as you did in steps 1 and 2. Let this stand for about a minute to allow the bacteria to incorporate the saffranin. Gram positive cells will incorporate little or no counterstain and will remain blue-violet in appearance. Gram negative bacteria, however, take on a pink color and are easily distinguishable from the Gram positives. Again, rinse with water for 5 seconds to remove any excess of dye.




⬌After you have completed steps 1 through 4, you should blot the slide gently with bibulous paper or allow it to air dry before viewing it under the microscope. DO NOT RUB THE SMEAR!
INSTAGRAM
https://www.instagram.com/microbiologylab_turkey/

 FACEBOOK
https://m.facebook.com/mikrobiyolojilab/

0
By on Hiç yorum yok:
Etiketler: , , , , , , , , , , , , , , , , , , ,
Eylül 26, 2018

GRAM BOYAMA

                                        GRAM BOYAMA 

Gram boyama tekniği, mikrobiyolojide sık kullanılan bir boyama yöntemi olup mikroorganizmaların sınıflandırılmasında ve tanımlanmasında kullanılır. Gram boyama ile bakteriler “gram pozitif’ (gram olumlu) ve “gram negatif’ (gram olumsuz) olarak ikiye ayrılır.

Basillerin yaklaşık yarısı, kokların büyük kısmı ve mantarlar gram pozitiftir. Spiral şekilli bakteriler ise gram negatiftir. Gram pozitif bakterilere örnek olarak Staphylococcus aureus, Bacillus subtilis, Staphylococcus epidermidis verilebilir. Gram negatif bakterilere örnek olarak E.coli, Pseudomonas aeruginosa, Etıterobacter aerogenes verilebilir. Gram boyama için hazırlanacak preparatlarda kullanılacak kültürlerin genç (18-24 saatlik) olması gerekir. Daha yaşlı kültürlerle çalışılması durumunda yanlış sonuçlar alınabilir. Gram (+) bakteriler de gram (-) gibi değerlendirilebilir.

                                Gram boyama aşamaları ve her aşamada bakterilerin renkleri 

 En sık uygulanan gram boyama yönteminde aşağıdaki işlemler sırasıyla uygulanır: 
⇒ 1,2’de belirtildiği şekilde preparat hazırlanır (yayma, kurutma, tespit).
⇒ Preparatın üzerine kristal viyole boya çözeltisi eklenerek kaplanır ve 1 dakika beklenir.
⇒ Preparat bol distile suyla yıkanır.
⇒ Preparatın üzerine lugol çözeltisi eklenerek kaplanır ve 1 dakika beklenir.
⇒ Preparat distile suyla yıkanır.
⇒ Preparatın üzerine %95’lik etanol veya asit-alkol karışımı eklenerek 10-15 saniye beklenir.
⇒ Preparat distile suyla yıkanır.
⇒ Preparatın üzerine sulu fuksin veya safranin boya çözeltisi eklenerek kaplanır ve 30 saniye beklenir.
⇒ Preparat bol distile suyla yıkanır.
⇒ Preparat havada veya kurutma kâğıdı ile kurutulur.
⇒ Mikroskopta incelenir. Mor renkte görülen mikroorganizmalar gram (+), pembe-kırmızı renkte görülenler ise gram (-) olarak değerlendirilir.

Gram (+) ve gram (-) mikroorganizmaların tamamı kristal viyole boyası ile mor renge boyanırlar. Preparata eklenen lugol solüsyonu ile gram (+) bakterilerin oluşturdukları yapı, daha sonra ortama eklenen alkol ile giderilemez. Oysa gram (-) bakterilerin oluşturduğu yapı alkol ile giderilebilir. Bir başka deyişle, boya, bakteri hücresinden dışarıya salınır (dekolorizasyon).

Gram (-) bakterilerin renkleri alkolle gittiğinden ortama daha sonra eklenen sulu fuksin ile boyanır. Böylece gram (+) bakteriler mor renkte (kristal viyole rengi), gram (-) bakteriler pembe-kırmızı renkte (sulu fuksin rengi) boyanır.
Gram pozitif ve graın negatif hücre duvarı
Gram boyanma özelliği bakteri hücre duvarının (çeperi) yapısı ile ilgilidir. Hücre duvar yapıları arasındaki farklar: 
➨ Gram (+) bakterilerin hücre çeperinde gram (-) bakterilere göre daha kalın peptidoglikan tabakası mevcuttur. 
➨ Gram (+) bakterilerin hücre çeperinde karbonhidratlar, gram (-) bakterilerin hücre çeperinde lipidler fazladır. Karbonhidratlar alkolle dekolarizasyon esnasında dehidratasyona (su molekülünün açığa çıkması) uğrar. Porlar iyice büzüşür, daralır ve boya dışarı çıkamaz. Lipitler de ise alkol çözücüdür ve hücre çeperinde olan porlar daha çok açılarak genişler. 
➨ Gram (+) hücre çeperinde teikoik asit olmasına rağmen gram (-) yoktur.
INSTAGRAM

FACEBOOK




0
By on Hiç yorum yok:
Etiketler: , , , , , , , , , , , , , , , , , , ,