DNase Test: Introduction, Composition, Principle, Test Requirements, Procedure, Result -Interpretations, and Limitations

Deoxyribonuclease (DNase) Test Positive and Negative Bacteria

Introduction of DNase Test for Bacteria DNase tests positive and negative bacteria as shown below image. This test is useful for the presumptive identification of Staphylococcus aureus which produces the enzyme deoxyribonuclease (DNase) from other Staphylococci which do not produce DNase. This test is also positive in the following …

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MIU Test: Introduction, Principle, Composition, MIU Agar Preparation, Test Procedure, Result-Interpretation, and Keynotes

Motile and non-motile bacteria, indole positive and negative, urease positive and negative organisms on MIU agar demonstration

Introduction of MIU Test MIU test stands for motility indole urease test and it is used for three tests among them one for motility of bacteria, second for indole formation, and third for urea hydrolyzation test of bacteria. This assay is useful for the identification …

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Culture Media: Introduction, Common Ingredients, Types, Preparation, and Use of Common Culture Medium, Keynotes, and Related Images

Culture media with variety of microbes-Micrococcus growth on nutrient agar (upper left), Lactose fermenting(Lf) and non-lactose fermenting (NLF) colonies of Gram negative bacteria colonies on MacConkey medium, Hameophilus influenzae colony morphology on chocolate agar(lower left), beta-hemolytic colonies of Staphylococcus aureus( middle), and Pseudomonas aeruginosa antibiogram pattern on Muller-Hinton agar(MHA)

Introduction of Culture Media Culture media are required to grow the organisms and they are generally from clinical specimens to identify the causative agent. Common Ingredients of Culture Media Common Ingredients of Culture Media and their basic constituents are as follows- Water: It is the …

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Aeromonas hydrophila: Introduction, Identification Features, Keynotes, and Aeromonas Footages

Aeromonas hydrophila growth on MacConkey agar

Introduction of Aeromonas hydrophila Aeromonas hydrophila is a gram-negative, facultative anaerobe, rod-shaped motile(due to single polar flagellum) bacterium without capsule and spore having a size from 0.3-1.0 µm wide by 1.0-3.5 µm long. It is generally found in the aquatic environment. Its presence can not …

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Enterobacter cloacae: Introduction, Identification Features, Keynotes, and Enterobacter Footages

Encapsulated strain of Enterobacter aerogenes on MacConkey medium

Introduction of Enterobacter cloacae Enterobacter cloacae is a facultative anaerobic Gram-negative bacterium of size 0.3-0.6 x 0.8-2.0 μm. It is lacking capsule and spore and it is motile due to flagella which is a member of the Enterobacteriaceae family. E. cloacae is the normal gut …

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Shigella flexneri: Introduction, Identification Features, Keynotes, and Shigella Footages

Shigella boydii colony morphology on XLD agar

Introduction of Shigella flexneri Shigella are Gram-negative bacilli measuring about 1-3 µm X 0.5 µm. They are non-motile, non-encapsulated, non-sporing, and non-acid-fast bacteria belonging to the family Enterobacteriaceae. They cause an infectious disease called Shigellosis. There are four species or serogroups based on biochemical and …

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Salmonella Paratyphi: Introduction, Identification Features, Keynotes, and Salmonella Footages

Salmonella Serovar Paratyphi growth on Nutrient agar, Blood agar, MacConkey medium, BHI broth and Biochemical reactions in TSI, SIM, citrate and urea agar

Introduction Salmonella Paratyphi (serovar) belongs to Enterobacteriaceae and thus is a Gram-negative bacterium causing mild gastroenteritis to a life-threatening bloodstream infection. It causes paratyphoid fever and it is restricted to humans. Proper sanitation and hygiene may decrease its infection chance. Travelers must be cautious during …

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Proteus vulgaris: Introduction, Identification Features, Keynotes, and Proteus Footages

Dienes phenomenon of Proteus vulgaris strains

The genus Proteus was discovered in 1885 by Hauser and it is also named after a Greek god.  Proteus is a member of the family, Enterobacteriaceae and it is a Gram-negative, oxidase-negative, fimbriated, motile, non-sporing rod-shaped bacterium without capsule and having a size of 0.4–0.8 μm in diameter and …

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