MI03: Chemical Control of Microbes

What is the difference between a disinfectant and an antiseptic?

Disinfectant: use on inanimate surfaces to destroy pathogenic microorganisms

Antiseptic: use on living tissues

Which types of microbes are easy to kill with chemical disinfectants and which are hardest to kill?

Easiest → Enveloped viruses: HIV, Herpesviruses, Hepatitis B virus, Influenza viruses

Hardest → Non-enveloped viruses: Rhinoviruses, Rotavirus, Norovirus, HPV, HAV, Adenoviruses

What is a hospital disinfectant? What bacteria are effective to it?

It is used on inanimate objects in hospitals.

Salmonella enterica, Staphylococcus aureus, and pseudomonas aeruginosa.

What is a low-level disinfectant and what are the types of organisms each class of compound kills?

A low-level disinfectant is registrered as a hospital disinfectant. It can kill HIV and HBV (both enveloped viruses)

What is a intermediate-level disinfectant and what are the types of organisms each class of compound kills?

It is a hospital disinfectant that kills HIV, HBV, Mycobacterium tuberculosis (tuberculocidal). They also can inactivate vegetative bacteria, most fungi, and enveloped viruses

What is intermediate-level disinfectant not effective against?

Bacterial spores

What is a high-level disinfectant and what are the types of organisms each class of compound kills?

It is a type of disinfectant registered for use on critical and semi-critical patient care devices.

Kills spores, all viruses, fungi, vegetative bacteria, and mycobacteria.

Describe the antimicrobial class to which chlorine (bleach) belongs and how it works.

• Halogen Antimicrobial class

• It oxidize and denature enzymes/proteins which kills bacteria, bacterial spores, fungi, and viruses.

Describe what phenols and phenolics are and how they kill microorganisms.

Phenols: Strong and highly toxic microbicidal that disrupts cell walls, membranes, precipitate proteins.

Phenolics: its less toxic that phenol due to having added groups like -Cl.

What is glutaraldehyde and how does it work?

A sterilant with long term exposure or a high level disinfectant with a shorter exposure. Part of aldehydes group.

What are some desirable qualities of chemicals used as disinfectants, antiseptic or sterilants?

• Broad spectrum

• Fast-acting

• Not affected by physical factors

• Nontoxic

• Hypoallergenic

• Surface compatibility

What are some foods to be particularly careful with handling in the kitchen?

Sprouts (hard to wash) and raw meats.

What is bioburden?

Organic material present in body fluids (e.g. saliva and blood)

What effect does bioburden have on the efficacy of chemical disinfectants?

They can form protective covering on microorganisms (enhance survival).

How does one carry out disinfection in a clinical setting?

• Must clean before disinfecting

• Spray-wipe-spray

• Let disinfect set for recommended time

What is chlorhexidine?

It is a type of bisguanides. It is used as skin antiseptic or mouthrinse.

What are bisguanides?

Type of disinfectant known to disrupt membranes (but not phenolics).

What is an effective working concentration of ethyl or isopropyl alcohols for disinfections?

The best working concentration is 70% alcohol and 30% water.

What are some benefits of alcohols and some disadvantages?

Benefit: Compromise membrane integrity and denature proteins leading to coauglation.

Disadv: 100% alcohol is not a protein coagulant and will not be effective. It requires a certain concentration to work effectively.

What are QUATs? How do they work?

They are surface active detergents that affect enzymes and alter cell membrane permeability. They cannot kill pseudomonas.

What are the advantages of QUAT alcohols over QUATs? What are some examples of QUAT alcohols?

QUATs: bactericidal against gram pos. and active against enveloped viruses.

QUAT alcohols:

• Bactericidal, tuberculocidal, virucidal against enveloped viruses.

• Pleasant odor

• Low tissue toxicity

• Ex: Cavicide

How does hydrogen peroxide and peracetic acid work?

They produce highly reactive hydroxyl free radicals that damage proteins. Both are active against a wide range of organisms (like bacteria, yeasts, fungi, viruses, bacterial spores).

What is ethylene oxide? How does it work?

It is a high level disinfectant/sterilant. Known to sterilize and disinfect plastics and prepackaged devices, foods.

What are some advantages of using ethylene oxide for sterilization? What are some disadvantages?

Adv:

• high capacity for penetration

• doesn’t damage heatlabile materials

Disadv:

• slow and requires long cycle time (10-16 hrs)

• uses toxic/hazardous/explosive chemical

• retained in liquids and rubber materials for prolonged intervals