LAB WEEK 14 (Hand Washing)

Who discovered the importance of hand washing in preventing disease?

Ignaz Semmelweis

what disease did Ignaz find increased with lack of sanitary practices?

childbirth fever (puerperal sepsis)

Rates of childbirth fever were lower in which group?

women assisted by midwives and nurses who were not allowed in autopsy rooms and were more sanitary in handling patients

what disinfectant did Semmelweis enforce everyone to use on their hands?

solution of chloride of lime (bleach)

when was handwashing made an importance in preventing disease?

1846-1847

what was the childbirth fever rate before handwashing was implemented?

up to 20%

what are the three groups of normal skin microbiota?

Diptheroids, staphylococci, and fungi

diptheroids

Corynebacterium and Propionibacterium

where will you find diptheroids?

on oily regions of the body, where they degrade fatty secretions such as sebum

what is the most common skin diptheroid?

Propionibacterium acnes— an obligate anaerobe living in hair follicles where oxygen is limited

function of propionibacterium acnes

degrade sebum, the fatty secretion responsible for moisturizing the skin

where do staphylococci prefer to grow?

dry environments

why is staphylococci on our skin beneficial?

produces antimicrobial compunds that inhibit growth of other gram positive bacteria, and use available nutrients

what is an example of a staph bacteria that produces antimicrobial compunds?

S. epidermidis

what two strains of MRSA exist?

hospital acquired and community acquired

where can you find community acquired MRSA

school gyms and training facilities

what form of MRSA is more common: hospital acquired or community acquired?

community acquired— accounts for 79% of MRSA

dermatophytes

fungi that can cause infections of the hair, skin and nails, such as athletes foot, ringworm, jock itch

primary fungi

malassezia furfur

malassezia furfur

small, non pathogenic yeast that utilizes fatty substances for growth

transient bacteria

microbes that are not part of the persistent population that inhabit the skin

why is the normal microbiota difficult to remove?

they reside in hair follicles and are entrenched in the skin

____ effectively removes transient bacteria

antiseptic soaps

what opportunistic pathogen is associated with skin?

S. aureus

what percentage of the US population carries S. aureus as a part of their normal skin microbiota?

25%

T/F- The human skin is inhabited by a diverse group of microorganisms

True

why is it so important that surgeons scrub their hands prior to surgery even though they wear surgical gloves?

failure to do so increases transmission. even gloves are not fool proof and can rip, so scrubbing is very important

T/F- Skin staphylococci are generally coagulase negative, salt tolerant, tend to grow in dry areas, and are typified by staphylococcus epidermidis.

True

T/F - Solid food is often diluted one gram food to 9 grams sterile water and then homogenized, resulting in solid samples, unlike liquid samples, start testing at a 1:10 dilution

True

T/F - The MBRT ends when the milk sample has lost 80% of it's blue color, and the time is recorded.

True

T/F - Milk is pasteurized, rather than sterilized, because the heat required to sterilize milk would denature proteins, degrade nutrients, and severely alter the tatse, appearance, and usefulness of the beverage

True

T/F - Milk spoils at room temperature faster than refrigerated milk because many contaminating bacteria are mesophiles.

True

T/F - The heterotrophic medium in a HPC will allow many bacteria in the sample to grow, but despite being a complete medium, does not allow many or most bacteria in the sample to grow.

True

T/F - Approximately 45% of the US population carries coagulase-positive Staphylococcus aureus as part of their normal skin microflora.

False

T/F - The first study to directly prove a 99% reduction in disease transmission by using hand washing with disinfectant in a medical setting occurred in 1946 and 1947.

False

T/F - A common example of normal skin fungal microflora is Malassezia furfur.

True