Question

Learning Task 16-02: Disinfectants

Microorganism	Important Characteristics of the Microorganism	How Disinfectant affects the Cell Structure.
Clostridium Difficile
Papilloma virus
Bordetella Pertussis
Aspergillius
HIV
Staphylococcus

Answer 1

1) Clostridium Difficile

Characteristics : Clostridium is a genus of gram-positive, spore-forming bacteria belonging to the family Clostridiaceae. Vegetative cells are rod shaped and arranged in pairs or short chains. The majority of species are obligate anaerobes; however, some species can grow under aerobic conditions or are aerotolerant.

How disinfectant affect the cell structure : Composed of hydrogenperoxide(disinfectant), surface acting agents (surfactants), wetting agents (allows liquid to spread easier) and chelating agents (helps to reduce metal content and/or hardness of water), AHPs have proved successful in killing clostridium difficile pores.

2) Papilloma virus

Characteristics: Papillomaviruses are small, non-enveloped, icosahedral DNA viruses that have a diameter of 52–55 nm. The viral particles consist of a single double-stranded DNA molecule of about 8000 base-pairs (bp) that is bound to cellular histones and contained in a protein capsid composed of 72 pentameric capsomers.

How disinfectants affect the cell structure: The HPV16 quasivirions showed similar resistance to native virions, except for being susceptible to isopropanol, the triple phenolic and the lower concentration peracetic acid-silver (PAA-silver)-based disinfectant.

3) Bordetella pertussis

Characteristics: Bordetella pertussis are small, gram-negative, encapsulated, non-motile, coccobacilli with outer pili. They are generally about 0.5-1.0 µm in size 3 - 5 . Some have reported that the bacteria are covered with surface slime or biofilm composed of carbohydrates

How disinfectants affect the cell structure: It is susceptible to many disinfectants - 1% sodium hypochlorite, 70% ethanol, iodines, phenolics, glutaraldehyde, formaldehyde

4) Aspergillus

Characteristics:

The following are some of the morphological characteristics of Aspergillus Fumigatus:

• They produce spores of between 200 and 400 mm.
• The color of the stipes is gray around the apex.
• They have a smooth surface.
• They have a small, columnous globuse.
• The surface of the conidia is either smooth or spinose.

How disinfectants affect the cell structure: chlorexidine-cetrimide, benzalconium chloride and the chlorophenol derivative were efficient against Aspergillus isolated from veterinary environments, whereas sodium hypochlorite showed lower efficiency.

5) HIV

Characteristics: HIV is a spherical virus with an envelope comprised of a lipid bilayer and surface glycoproteins, gp120 and gp41, that attach to host cell receptors, CD4 and CCR5.

How disinfectants affect the cell structure: Many disinfectants recommended for use in health care facilities have been found to inactivate HIV in laboratory testing like Dilute household bleach, 70% isopropyl alcohols and dilute liquid dish detergent were the most active of the tested disinfectants. In practice, however, chemical disinfectants may not be reliable, because they may be inacti- vated by blood or other organic matter present.

6) Staphylococcus

Characteristics: Staphylococci are known as clustering Gram-positive cocci, nonmotile, non-spore forming facultatively anaerobic that classified in two main groups, coagulase-positive and coagulase-negative.Staphylococcus aureus is a non-motile, Gram-positive, catalase-positive and facultative anaerobic coccus. The bacterium occurs widely, in low numbers, on the skin and mucous membranes of warm-blooded animals. Normally, the bacterium is transient and not a part of the resident flora on skin.

How disinfectants affect the cell structure: hydrogen peroxide and sodium hypochlorite products are effective against S. aureus and P. aeruginosa biofilms, which can be common in healthcare facilities. However, quaternary ammonium chloride compounds are not as effective. Hydrogen peroxide kills Staphylococcus aureus by reacting with staphylococcal iron to form hydroxyl radical.