bacteria that prefer cold temps

refridgerator temp 4C

thrive in cold ocean water

pH >8.5

ex environment in SI

pH 2-5

live in stomach

may be liquid (broth, in tube) or solid (mixed with agar, petri dish)

may be chemically defined-exact chemical components known or complex-made with part of extracts of animals, yeast, plants. exact chemicals not known

contains ingredients that inhibit the growth of some organsims but allow the growth of others

ex: MacConky agar inhibits growth of gram pos bacteria

inoculation-adding microorganisms to a tube or plate of medium

incubation- put inoculated specimen in favorable temp & atmosphere. wait for bacteria to grow

pure culture- tube or plate containing only one kind of microorganism

CO2 incubators, 5-10%CO2

non-CO2 incubator, room air

anaerobic incubator, devoid of oxygen

lag phase- bacteria absorb nutrients, synthesize enzymes, don't replicate

logarithmic growth phase- bacteria multiply rapidly, # cells double with each generation time

sationary phase- nutrients start to run out, waste products build up, growth slow down & equals rate of death

death/decline phase- bacteria die at rapid rate, some may form endospores

if there's a lot, measure light absorbance with spectrophotometer

or, make dilutions of the sample and inoculate plates or solid medium w/specified volume of sample dilution

incubate

count # of colonies on the plate and multiply by dilution factor

no single medium cluture best for growing fungi

media often contains antibiotics to inhibit bacterial growth and/or are acidic-also inhibits bacterial growth

some fungi are highly infectious

use of antiseptic agent to prevent infection

developed by Joseph Lister in 1867

practical, efficient, inexpensive

effectiveness depends on time and temp

thermal death point (TDP)-lowest temp that will kill all organisms in pure culture within a specified time

thermal death time (TDT)-lenght of time necessary to sterilize a pure culture at specified temp

160-165C for 2hrs or 180C for 1hr

heat must thoroughly penetrate material

moist or protein-laden materials can decrease effectiveness

boiling for 30min kills vegetative forms of most pathogens but not endospores

autoclaving at pressure of 15psi at 121.5C for 20 min destroys vegetative microorganisms, bacterial endospores, viruses

cold and desiccation

ex:freeze-drying

used to reduce microbes in the air

UV rays cause DNA damage

also prevents food spoilage, sterilization of heat-sensitive surgical equiptment

prior cleaning of surface

organic load

bioburden (type & # of microbes)

concentration of disinfectant

contact time

surface texture

temp & pH

soap, detergent

alcohols, phenols

halogens

hydrogen peroxide

heavy metal salts

formaldehyde, ethylene oxide

enzyme inactivation (peroxide, halogens)

cell membrane damage (soap, detergent)

DNA damage (formalin)

inhibit cell wall synthesis

damage cell membranes

inhibit nucleic acid (DNA/RNA) synthesis

inhibit protien synthesis

inhibit enzyme activity

competative inhibitors

compete with folic acid, without folic acid bacteria cannot produce some essential protients

bactericidal

cell wall synthesis

bacteriostatic

target bacterial ribosomes, inhibit protien synthesis

bactericidal

inhibit protein synthesis, effective agent against many aerobic gram-neg bacteria

eg. erythromycin

bacteriostatic at lower doses, bactericidal at high

protein synthesis

eg. ciprofloxacin

bactericidal, inhibit DNA snythesis

difficult to target because they are eukaryotic organisms

interfere with cell membrane sterols or block mitosis/nucleic acid synthesis

tricky because of replication in host cell

interferes with reproduction

superbugs

MRSA

methicillin-resistant Staphoylococcus aureus (MRSA)

still susceptible of vacomycin

vancomycin-resistant strains (VISA, VRSA)

superbugs

VRE

vancomycin-resistant Enterococcus sppe. 

common UTI

superbugs

TB

multidrug-resistant Mycobacterium tuberculosos (MDR-TB)

resistant to first-line drugs

XDR-TB: also resistant to second-line drugs

some strains resistant to all drugs

lack specific target of antibiotic

unable to cross cell wall/membrane

if bacteria was once susceptible

changes in drug-binding sites, cell membrane permeability

produce drug destroying-enzyme

pump drug out of cell before it can cause damage

trasformation-cell absorbs DNA from environment

transduction-carry across from bacteriophages

conjugation-most common method

undesirable effects of antimicrobials

toxicity

chloramphenicol- aplastic anemia

steptomycin- deafness

primarily anaerobic bacteria and fungi

staphylococcus spp. most common

# and type depend on: moisture, pH, temp, salinity, presence of chem wastes & other microbes

middle & inner ear usually sterile

outer ear, same as skin

sparse on eye

upper (nasal passages & throat)- abundant

lower (larynx, trachea, bronchi, lungs)- sterile

numerous anaerobic & aerobic bacteria

cause: dental caries, gingivitis, periodontitis

stomach-low pH-Helicobacter pylori

proximal SI-sterile (bile)

colon- 500-600 mostly obligate, aerotolerant, facultative anaerobes, many are opportunists

kindeys, ureters, bladder usually sterile

distal urethra-UTIs (E.coli)

sexual transmission-Chlamydia trachomatis, Neisseria gonorrhoeae, mycoplasmas

of skin, mucus memebranes, GI tract

population of microbes that temporarily joins the endogenous microflora

removed by washing, skin sloughing, or find conditions uncongenial or out-competed by other microbes

form on urinary catheters & medical equipment

cause disease-endocarditis, dental caries, cystic fibrosis, kidney stones, middle ear infections

beneficial to one and detrimental to the other

ecto-surface of host

endo-inside of the host

study of disease

frequency, distribution, determinates develop ways to prevent, control, or eradicate diseases

possible to spread, may not be easy

gonorrhea

spreads easily from person to person

flu

number of NEW cases of disease during a specific time period

period prevalence-# of cases existing in a population during a specified time period

point prevalence- # of cases existing at a particular moment in time

always present

TB, STDs, common cold

1 coliform or less per 100ml water

acceptable amout of bacteria in water

direct skin-to-skin

direct mucus membrane to mucus membrane

indirect: airborne or droplet, food or water, formites

transfusion, contaminated blood/needle

eliminate or contain reservoir

prevent contact and exit pathway

eliminate means of transmission

block entryway

reduce susceptibility of new host (vaccine)

UTIs- 13% HAI deaths

surgical site 8%

lower respiratory (pneumonia) 36%

bloodstream (septicemia) 31%

AAD- antibiotic associated diarrhea, caused by enterotoxin

PMC- pseudomembranous colitis, caused by C.diff cytotoxin. lining of colon sloughs off resulting in bloody stool

elderly

women in labor & delivery

premature infants & newborns

surgical & burn pt

diabetic & cancer pt

pt receiving steroids, anticancer drugs, antilymphocyte serum, radiation

innumosuppressed, renal dialysis/catheterization

presence of microorganisms in hospital environment

immunocompromised pt

transmission of pathogens between staff and pt and among patients

clean technique

goal: exclude pathogens

sterile techniques

goal: exclude all microorganisms

practices used to render objects sterile

air being removed from room is filtered

room is under negative pressure

air entering from hallway

air entering room is filtered

room is under positive pressure

air from pt room enters hallway

protect pt from everyone else