HOSA ILC Microbiology Ch2

Antonie van Leeuwenhoek

The first person to see bacteria through a microscope

mold therapy

mold was used to treat infections in the past

Robert Hooke

developed microscopes with more powerful magnification

Robert Koch

developed staining of bacteria

Ignaz Semmelweiss

Traced the cause of puerperal sepsis to lack of handwashing

Joseph Lister

discovered how antiseptics prevented infection (especially during surgery)

opportunistic infections

infections from defective immune system that can't protect against normal flora

serology

study of fluid components in blood (especially antigens & antibodies)

binomial nomenclature system

genus (family name, capitalized) and species (lowercase)

Glycocalyx

protective layer of glycoprotein on outer surface of cell membrane

capsule

type of glycocalyx that is tightly attached to bacterium w definite boundaries

slime layer

time of glycocalyx that is loosely attached & can easily wash off

functions of glycocalyx?

cell adhesion, forms antigens, increase microbial resistance

simple stain

allows for contrast to better illustrate structure & arrangement of bacterial cells

differential stain

provides more info based on composition of bacterial cell wall

what is the Gram stain procedure?

1) place bacteria on slide; 2) stain w crystal violet; 3) wash slide w water; 4) flood slide w Gram's iodine; 5) apply alcohol decolorizing rinse; 6) check results & record if purple; 6) restain w safranin

Gram stain results = bacteria is purple

bacteria is gram-positive

Gram stain results = bacteria is pink/red

bacteria is gram-negative

acid-fast (Ziehl-Neelsen) stain

application of acid-alcohol does not cause decolorization, maintaining a dark stain

what organisms is the acid-fast stain used on?

Mycobacterium (causes TB & leprosy)

Acid-fast stain results = bacteria appear red against blue background

bacteria is acid-fast

Acid-fast stain results = bacteria appear blue

bacteria is no acid-fast

acid-fast bacteria

have glycolipid (sugar + fat molecule) and mycolic acid layer in cell wall

culture and sensitivity (C&S) test

determines which particular bacteria are present and which antibiotics are effective against them

primary culture

the first culture; usually after 24-48 hours of incubation

what must be done to mixed cultures?

must be separated into subcultures until it becomes a pure culture

pure culture

only 1 microbe species in a culture

what do culture media usually contain?

simple nutrients (water, C, H, N, O, S, Ca, Mg, K) and complex nutrients (sugar, amino acids, blood products)

purpose of incubator?

provides stable temp & humidity level for optimal growth

how long does it take for preliminary identification (not specific species)?

1-2 days

disk diffusion

culture grows on solid media; antibiotic paper disks are paced in lawns of bacteria

zone of inhibition

zones around antibiotic disks where bacteria doesn't grow

broth dilution

organism is placed in different [ ]s of antimicrobial agent & liquid growth medium

minimal inhibitory concentration (MIC)

lowest concentration of drug that INHIBITS GROWTH of pathogen

Minimum bactericidal concentration (MBC)

The lowest concentration of an antibiotic that KILLS the test cells.

how is Minimum Bactericidal Concentration calculated?

take sample from each clear MIC tube & culture on agar plate; [ ] w no significant bacterial growth is MBC

when is organism considered resistant?

Minimum Inhibitory Concentration cannot be safely achieved in patient

when is organism considered sensitive?

MIC is clinically achievable level

when is organism considered intermediate?

MIC is at level that may or may not be clinically achievable

empiric therapy

antimicrobials are used to treat infection b4 organism has been identified in serious cases

endotoxin

portion of outer cell membrane is shed by bacteria; only in gram - bacteria xcept Listeria (gram +)

are aerobic or anaerobic infections more serious?

anaerobic infections; they also hv less antibiotic options

are gram + or gram - infections harder to treat?

gram - bc more layers in cell wall

2 ways bacteria become resistant using bacterial enzymes?

bacterial enzymes are produced that inactivate the antibiotic or prevent drug from attaching to binding site

4 reasons why bacterial resistance occurs?

overuse of broad-spectrum antibiotics, misuse of antibiotics, bacterial enzymes, stopping medication after "feeling better"