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Physiology
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Study of life processes or study of things that living organism do in order to stay alive
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Selective media
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allow certain types of organisms to grow while inhibiting the growth of other organisms, dye, heavy metals, or antibiotic is added to the medium
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Enrichment medium
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growth of one organism is favored without inhibiting the growth of others
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Differential medium
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does not necessarily inhibit bacterial growth but makes the bacteria look different, works best with closely related organisms
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differential agent
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what causes the bacteria to look different in differential media
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Blood agar is a type of ________ media used to ________
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differential, differentiate hemolytic vs nonhemolytic bacteria
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What happens when hemolytic bacteria is placed on blood agar?
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A clear ring forms around the bacteria
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What happens when nonhemolytic bacteria is placed on blood agar?
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Growth media remains red
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Manitol Salt Agar is both
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selective and differential
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What does MSA select for?
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organisms with a high salt tolerance (normally staphylococcus )
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What does MSA differentiate between?
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organisms that can ferment mannitol (pathogenic) and organisms that cannot
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What indicator is used in MSA
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phenol red, which turns yellow when under acidic conditions
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EMB is both
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selective and differential
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EMB selects for
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gram negative organisms
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EMB differentiates between
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lactose fermenting coliforms and nonlactose fermenting coliforms
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When Ecoli is placed on an EMB Plate what happens?
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colonies will form, and a metallic green sheen (maybe pink) will develop
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What did we add to starch agar?
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Gram's Iodine
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What genus of bacteria is capable of breaking down starch? How does the addition of iodine show this?
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Bacillus have exoamylase which breaks down starches, when iodine is added if the starch has been degraded, it has nothing to bind to therefore a ring will show around the bacteria.
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TSI Agar contains
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peptone, glucose, sucrose, lactose, thiosulfate
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TSI stands for
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triple sugar iron agar
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What does TSI differentiate between?
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ferment the three sugars, and reduce sulfur to hydrogen sulfide
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What is TSI used to distinguish between?
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enterobacteriacaea , (e coli, salmonella-shingella)
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TSI colors
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Red/Red - peptone catabolized no sugar fermentation
Red/yellow- Glucose fermented only
Yellow/Yellow w/ CO2- glucose, lactose and or sucrose
Red/ yellow w/ black- glucose only fermented but it reduces sulfate
Red/yellow- Glucose fermented only
Yellow/Yellow w/ CO2- glucose, lactose and or sucrose
Red/ yellow w/ black- glucose only fermented but it reduces sulfate
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Enterobacteriae are
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bacteria that affect the GI tract
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Opportunistic organisms only cause disease
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when someone is already immuno compromised
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Coliform
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general term for lactose fermentation gram negative rods that inhibit the intestinal tract of man and other animals , normally free living saprophytes
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chemotherapeutic agents
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Term includes antibiotics and man made compounds
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What is a drug
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All pharmacologically active compounds
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Uses of chemotherapeutic agents in medicine
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Chemotherapy and prophylaxis
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intensive farming
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Pigs and chickens given antibiotics to reduce change of infection
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Horticulture
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Used on diseased plants to kill to microorganisms
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Major sources of antibiotics
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- Streptomyces (bacteria)
-Penicillium (fungi) and sometimes cephalosporin produced from fungi
-Penicillium (fungi) and sometimes cephalosporin produced from fungi
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Penicillin does not
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Directly kill the organism, it targets the peptidoglycan cell wall so water can enter
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selective toxicity
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A drug that kills harmful microbes without damaging the host
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Concentration
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Compared to acids, alcohols, the concentration of antibiotic is approx 100x lower or perhaps greater
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broad spectrum
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Active on gram positive and gram negative
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narrow spectrum
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Active on restricted group of bacteria
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bacteriacidal
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Kills the target osthogen
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Bacterioststic
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Reversible inhibits growth
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dilution susceptibility test
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Used to determine mic and mlc values
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Kirby-Bauer Test
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disk diffusion test essential for groups of bacteria commonly showing resistance. (drug susceptibility)
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What broth is used on plates in the Kirby Bauer test
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Mueller Hinton broth
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MIC
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The lowest concentration of antibiotic resulting in no growth after 16-20 hours
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MLC
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The lowest antibiotic from which the microorganisms do not recover and grow when transferred to fresh medium (kills)
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An alternative to the Kirby Bauer procedure
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The e test
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potable water
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Clean water free of all objectionable material
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Fresh water
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Non salt or sea water
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pollution
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Anything that makes it non potable
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sewage
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The community este or garbage that Mother Nature and we dump into sewers or land
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drinking water
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No coliform contamination acceptable
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recreational water
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200 fecal coliforms/ 100ml
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Fish and wildlife habitat
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5000 fecal coliforms/ 100 ml
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T or F water contaminants may not be stopped by water filtering
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True
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Chlorination and UV water treatment
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50-100ppm, contact for at least 6 hrs
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What size filter is used for water?
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.45 microM membrane filter
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Hepatitis A
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Inflammation and necrosis tissue death of liver
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Norwalk type virus
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acute gastroenteritis
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Rotaviruses
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Active gastroenteritis , especially in children
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Enteroviruses
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many types affect intestines and upper respiratory tract
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Reoviruses
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Infect intestines and upper respiratory tract
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What strain of bacteria has been isolated in 70% of fatal flesh eating bacteria wounds from salt water oceans and seas in humans
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Streptococcus pyogenes
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Chloera
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Transmitted through water, fresh vegetables, and shellfish, 1991 epidemic (over 1 million cases), common in Asia Africa and Latin America
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T or F coliforms always serve as indicators of fecal contamination
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False, some coliform bacteria like enterobacter aerogenes are non fecal originating
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Fecal coliform in the usa
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Escherichia E coli
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Fecal coliform in Europe
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Fecal streptococci
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Coliforms belonging to enterobacteriaceae
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Facultative anaerobe, gram negative, non spore forming, rod shaped
Ferment lactose and produce gas and acid within a day or 2 at 35-44.5 C
Most abundant bacterium of human Colon, most important indicator of human fecal contamination
Ferment lactose and produce gas and acid within a day or 2 at 35-44.5 C
Most abundant bacterium of human Colon, most important indicator of human fecal contamination
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Bacteria indicator organism common groups
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Coliforms, streptococci, and spore formers
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Bacteriological testing of water only
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Report negative or positive results, do not count
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What is used in routine monitoring of water quality
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Indicator organisms ( for e coli)
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Two standard methods of counting bacteria
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Standard plate count , used for samples that have large number of bacteria
The most probably number , used when the number of bacteria to be counted is so low
The most probably number , used when the number of bacteria to be counted is so low
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Method we used for counting bacteria
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Most probably number
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In the real world bacteria are
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Randomly but not evenly distributed
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MPN technique is used to
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Estimate coliform bacteria not total number of bacteria in water sample , or tell if bacteria is pathogenic
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Because of uneven distribution of bacteria in water we use
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3 replicas
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3 steps of MPN
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Presumptive test
Confirmed test
Completed test ( we skipped)
Confirmed test
Completed test ( we skipped)
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The presumptive test
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Samples are inoculated into a lactose broth containing a Durham tube, in a positive culture growth will occur with the production of both acid and gas which is a good indication of coliform presence
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The confirmed test
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Non coliform bacteria can yield false positive results, so we take all the positive lactose broth cultures and swab them onto an EMB agar plate , producing positive results when colonies growth with a green metallic sheen
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EMB agar in presence of ecoli and klebsiella pneumoniae
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Dark center and green metallic sheen
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Enterobacter aerogenes on EMB
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Pink colonies with no sheen
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Proteus mirabilis and salmonella typhimurium on EMB
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Colorless colonies
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