Introduction

Question 1

Biocide is a general term describing

Answer 1

a chemical agent, usually broad-spectrum, that inactivates the microorganisms

Question 2

Sterilization refers

Answer 2

to a physical or chemical process that completely destroys or removes all microbial organisms including spores.

Question 3

Disinfection refers

Answer 3

to the physical or chemical process of inactivation or removal of pathogenic microorganisms to the point where they no longer cause diseases

Question 4

The effectiveness of disinfectant is determined by the following factors;

Answer 4

Nature of material
Number of microbes
Resistance of microbes
Organic soil
Concentration of disinfectants
Exposure time 
Temperature

Question 5

Types of Disinfectants and Antiseptics

Answer 5

Alcohols
Aldehydes
Biguanides
Halogen Releasing Agents 
Phenols 
Heavy Metal Derivatives 
Quaternary Ammonium Compounds
Dyes
Heat
Acids

Question 6

Aldehydes

Answer 6

Formaldehyde & Glutaraldehyde are frequently used
Formaldehyde is bactericidal, sporicidal & has a lethal effect on viruses.
Glutaraldehyde is effective against Tubercle bacilli, fungi and viruses.

Question 7

Uses of Formaldehyde

Answer 7

To preserve anatomical specimens
Destroying Anthrax spores in hair and wool
10% Formalin+0.5% Sodium tetra borate is used to sterilise metal instruments

Question 8

Uses of Glutaraldehyde

Answer 8

Used to treat corrugated rubber anesthetic tubes, Face masks, Plastic endotracheal tubes, Metal instruments and polythene tubing

Question 9

Aniline dyes

Answer 9

Are Brilliant green, Malachite green & Crystal violet

Active against Gram positive bacteria

No activity against tubercle bacilli

Question 10

Acridine dyes

Answer 10

Acridine dyes in use are orange in colour

Effective against Gram positive than Gram negative

Important dyes are Proflavine, Acriflavine,Euflavine

Question 11

Halogens

Answer 11

Iodine in aqueous and alcoholic solution has been used widely as a skin disinfectant
Actively bactericidal with moderate against spores
Chlorine and its compounds have been used as disinfectants in water supplies & swimming pools

Question 12

Phenols

Answer 12

Obtained by distillation of coal tar
Phenols are powerful microbicidal substances
Phenolic derivatives have been widely used as disinfectants for various purposes in hospitals
Eg: Lysol, cresol, detol etc

Question 13

Phenol (uses)

Answer 13

Various combinations are used in the control of pyogenic cocci in surgical & neonatal units in hospitals.

Aqueous solutions are used in treatment of wounds

Question 14

Metallic Salts

Answer 14

The salts of silver, copper and mercury are used as disinfectants.

Act by coagulating proteins

Marked bacteriostatic, weak bactericidal and limited fungicidal activity

Question 15

Testing of disinfectants

Answer 15

Rideal Walker test 
Chick Martin Test
The capacity test (Kelsey Sykes) 
The stability test (Maurer) 
The “in use” (Kelsey and Maurer) test