Why is Micrococcus luteus Gram-positive?

Why is Micrococcus luteus Gram-positive?

Micrococcus luteus is a Gram-positive, to Gram-variable, nonmotile, coccus, tetrad-arranging, pigmented, saprotrophic bacterium that belongs to the family Micrococcaceae. It is urease and catalase positive.

Is micrococcus Gram-positive or negative?

Micrococcus spp. are Gram-positive aerobic spherical cocci. They are catalase positive, reduce nitrate to nitrite and are usually non-motile.

What does Micrococcus luteus do?

Micrococcus luteus degrades the compounds in sweat into ones producing unpleasant odors. It also has the ability to degrade pollutants such as petrol. Pathogenicity: Although generally a harmless saprophyte, Micrococcus luteus can act as an opportunistic pathogen.

Is M Luteus oxidase negative?

The negative oxidase result conflicts with M. M. luteus is an obligate aerobe (Medical Laboratories). The positive catalase result lines up with M.

What shape is Micrococcus luteus?

M. luteus was first known as Micrococcus lysodeikticus and was discovered by Alexander Fleming in 1928. Its name stands for: microscopic (micro), of spherical shape (coccus), and yellow (luteus).

Is Micrococcus luteus acid fast positive or negative?

Bacteria Collection: Micrococcus luteus Additional Information

Fermentation Tests Text: Maltose : -,Salicin : –
Cells Length (µm): 1|1|1|1
GramReaction Text: positive
Acid Fast Staining Text: negative
Motility At 25°C Text: negative

Is Micrococcus luteus a lactose fermenter?

As the microbe is gram positive this means that it has a large peptidoglycan layer and lacks a lipopolysaccharide layer. The MacConkey agar is selective for gram-negative which is why my microbe didn’t show much growth on it, and because it didn’t change colors it means it didn’t ferment the lactose.

What organisms are acid fast positive?

Common acid-fast bacteria of medical importance include Mycobacterium tuberculosis, Mycobacterium leprae,Mycobacterium avium-intracellulare complex, and Nocardia species.

What is the mordant in acid fast staining?

During the acid fast stain, heat is used as a mordant to allow the primary stain to penetrate the waxy mycolic acid layer. The heat will prevent the cells from being destained using acid-alcohol.

Which mordant is used in ZN staining?

Unlike the Ziehl–Neelsen stain (Z-N stain), the Kinyoun method of staining does not require heating. In the Ziehl–Neelsen stain, heat acts as a physical mordant while phenol (carbol of carbol fuschin) acts as the chemical mordant.

What is modified Zn stain?

The Modified Ziehl-Neelsen stain (mZN stain) is a type of differential bacteriological stain used to identify acid-fast organisms, mainly Mycobacteria. Acid fast organisms are those which are capable of retaining the primary stain when treated with an acid (fast=holding capacity).

Is smear negative TB infectious?

Sputum smear microscopy is commonly used for diagnosing tuberculosis (TB). Although patients with sputum smear–negative TB are less infectious than patients with smear-positive TB, they also contribute to TB transmission.

What is no acid fast bacilli seen?

A normal result for an acid-fast bacteria smear is negative, meaning no bacteria were found in the sputum sample. A positive result means that bacteria were found and that you may have an infection. The smear is treated with a special acid-fast stain that can provide a preliminary test result in 24 hours.

How is TB confirmed?

Additional tests are required to confirm TB disease. The Mantoux tuberculin skin test is performed by injecting a small amount of fluid called tuberculin into the skin in the lower part of the arm. The test is read within 48 to 72 hours by a trained health care worker, who looks for a reaction (induration) on the arm.

What are the causes of false negative acid fast smear?

AFB cross-contamination from one slide to another. Presence of food particles. Precipitation of stains. Transfer of acid-fast bacilli through oil on the immersion lens.

What is Genexpert test?

Introduction: Gene-Xpert, a CBNAAT (catridge based nucleic acid amplification test) is a widely accepted diagnostic test for Tuberculosis. This test is a rapid diagnostic test for Tuberculosis detection as well as Rifampicin resistance in direct smear negative cases.