What is Enterobacter cloacae ?
One sort of bacterium that is frequently found in the environment is called Enterobacter cloacae, and Enterobacter cloacae is mainly found in soil, water, and the intestines of humans and animals. It is regarded as an opportunistic pathogen, which means that while it typically doesn’t cause illness in healthy people, it can infect those who have compromised immune systems or underlying medical issues.
Table of Contents
Biochemical Tests for Enterobacter cloacae
Enterobacter cloacae is a common Gram-negative bacterium found in the environment, including soil, water, and the gastrointestinal tract of humans and animals. It is typically considered an opportunistic pathogen, meaning it can cause infections in individuals with weakened immune systems.
Accurate identification of E. cloacae is crucial for clinical management and treatment. Biochemical tests play a vital role in this process. Here are some key biochemical tests used to identify E. cloacae
Gram-Stained
Under a microscope, E. cloacae appears pink or red and is Gram-negative.
Test for Oxidase
Since E. cloacae lacks the oxidase enzyme, it cannot make cytochrome c oxidase. In order to do this test, a reagent is added, which, if the enzyme is present, reacts with it to change colour.
Test of Motility
E. cloacae may move on its own and is usually motile. A motility agar plate or the hanging drop method can be used to observe this.
Glucose Fermentation
When glucose is fermented, E. cloacae produces gas and acid. A favourable outcome is indicated by a colour change and/or gas production in a glucose fermentation broth test.
Test of Indole
Because it lacks the enzyme tryptophanase, which converts tryptophan to indole, E. cloacae is considered to be indole-negative. Kovac’s reagent, which interacts with indole to produce a red colour shift if present, is used in this test.
Test for Methyl Red
Because E. cloacae is methyl red-positive, it creates mixed acids during the fermentation of glucose, which lowers the pH to less than 4.4. Methyl red indicator, which turns red in an acidic environment, is used to test this.
Test of Citrate Utilization
Because E. cloacae is citrate-positive, it can obtain all of its carbon from citrate. Simmons citrate agar is used to test this; growth on the agar signifies a successful outcome.
Test for Lysine Decarboxylase
Since E. cloacae is positive for lysine decarboxylase, it has the ability to decarboxylate lysine and produce cadaverine. A favourable result is shown by a change in colour from purple to yellow in lysine decarboxylase broth.
Test for Ornithine Decarboxylase
Because E. cloacae is ornithine decarboxylase-positive, putrescine can be produced when ornithine is decarboxylated. A positive result is shown by a colour change from purple to yellow in the ornithine decarboxylase broth test.
Test for arginine Di hydrolase
Because E. cloacae is arginine Di hydrolase-positive, it can break down arginine and produce ammonia and ornithine. A positive result is shown by a colour change from purple to yellow in the arginine Di hydrolase broth test.
Test of H2S Production
Since E. cloacae normally produces no hydrogen sulphide, it is said to be H2S-negative. This is tested in a sulfur-containing solution; a black precipitate signifies a successful outcome.
Test for Gelatinase
Because E. cloacae is gelatinase-positive, it has the ability to hydrolyze the protein gelatin. A clean zone surrounding the growth on a gelatin agar plate, which is used for testing, shows a positive outcome.
Test for Phenylalanine Deaminase
Since E. cloacae lacks phenylalanine deaminase, it is unable to deaminate phenylalanine. Phenylalanine agar is used to test this; a change in colour to green signifies a favourable outcome.
DNase Examination
Since E. cloacae is DNase-positive, DNA can be broken down by it. A clear zone surrounding the growth on a DNase agar plate shows a positive result for this test.
Testing for Antibiotic Susceptibility
Antibiotics such as cefazolin, ampicillin, and penicillin can cause resistance in E. cloacae. The right antibiotic medication must be chosen with the help of susceptibility testing.
Note: Although these biochemical assays can aid in the identification of E. cloacae, further molecular testing, such as PCR or 16S rRNA sequencing, is frequently necessary for confirmation.
Frequently Asked Questions(FAQ)
What is Enterobacter cloacae ?
One sort of bacterium that is frequently found in the environment is called Enterobacter cloacae, and it is mainly found in soil, water, and the intestines of humans and animals. It is regarded as an opportunistic pathogen, which means that while it typically doesn’t cause illness in healthy people, it can infect those who have compromised immune systems or underlying medical issues.
What is the result from DNase Examination?
Since E. cloacae is DNase-positive, DNA can be broken down by it. A clear zone surrounding the growth on a DNase agar plate shows a positive result for this test.
Related Articles
