Micro II Final Exam

Strain of M. Bovis which is used to produce the M. tuberculosis vaccine

Attenuated strain used of TB vaccine (Bacille-calmete- Guerin, BCG)

Mycobacterium species which cannot be cultured in the laboratory routinely (requires living cells) 

Mycobacterium leprae 

mycobacteria associated with AIDS 

MAC complex 

Rapid grower

visible growth in <7 days (upon subculture)

slow grower

Require >7 days on solid media under ideal culture conditions

Scotochromgoen 

pigment produced in either light or dark 

Photochromogen

pigment produced only when exposed to light

Nonchromogen

no pigment production

Carotenoid pigments 

yellow, orange rare pink pigments 

list the special requirements of isolation of M. haemophilum

requires hemming (CHOH) because is fastidious

When is it appropriate to submit a stool sample for mycobacterial culture

detection of mycobacterium avian complex in AIDS patients

Contamination rate that mycobacteria labs should strive for when assessing their decontamination process 

2-5% 

fluorescent stain that is specific for acid-fast organisms and is the best choice for screening specimens

auramine-rhodamine stain

Where are all cultures set up

in solid media and broth media

Temperature for skin cultures 

30C 

temperatures for sputum/respiratory cultures

37C

how long should mycobacteria cultures should be incubated before reporting final results

6-8 weeks

what factor seen microscopically is suggestive of M. tuberculosis and indicates virulence 

cording factor (serpentine arrangement) 

2nd most common cause of NTM lung disease

mycobacterium kansasii

disease caused by M. ulcerans

burly ulcer/ Bairnsdale ulcer

microscopic appearance of M/ kansasii when stained with a carbofuchsin stain 

long rods with distinct cross banding (candy cane) 

most common type of infection and route of transmission associated with M. marinnum

cutaneous lesion or ulcers

Mycobacterium species which is generally nonpathogenic and common contaminant in the AFB lab

mycobacterium gordonae

scrofula 

lymphadenopathy and draining wound in neck of children 

which mycobacterium is commonly implicated in scrofula

mycobacterium scrofulaceum

Rapidly-growing mycobacteria that is associated with cystic fibrosis patients

mycobacterium abscessus

Extensively drug-resistant TB (XDR-TB) 

resistant to rifampin, isoniazid, quinolones, and other drugs 

multidrug resistance TB (MDR-TB)

resistant to rifampin and ionized

Turnaround time for conventional ID

1-3 days after specimen received from lab

Turn around time for MALDI-TOP MS ID

within minutes

Duplex/ hybrid 

ds structure formed when two complementary ss nucleic acids anneal together by base pairing 

Stringency

conditions set for optimal target-probe binding

low stringency

forgiving, less base-pairing required

high stringency 

strict, high degree of base-pairing 

Denaturation stage of PCR temperature

94C

Primer annealing stage of PCR temperature

55-62C

Elongation stage of PCR temperature 

72C 

Method of DNA denaturation during PCR

separation of complementary dsDNa to ssDNA

General design of primer used in PCR

genus-specific, specifies-specific, antimicrobial resistance genes

most common targets used for PCR amplification of bacterial nucleic acid 

16s rRNA and 23s rRNA 

Why Taq DNA polymerase is the enzyme utilized in most PCR reactions

Stable at higher temperatures through several amplification cycles

Amplicon

amplified PCR product

What phase of End-Point PCR is monitored 

Plateae pahse 

What phase of Real time PCR is monitored 

Exponential phase

Threshold cycle

cycle number at which the fluorescence crosses background threshold

Relationship between Ct value and amount of initial target sequence present

Inversely related

Melting temperature 

temp at which 50% of DNA denatures into two strands (melts) 

Principle of Multiplex PCR

allows detection of multiple target in a single reaction

Anaerobe

bacterium that is able to replicate without oxygen

Polymicrobial

the infections process or site of infection contains many different organisms at site

Pleomorphic

variable number of shapes, sixes, and forms

Strict obligate anaerobe

extremely oxygen sensitive and killed by its presence

Aerotolerant anaerobes

tolerate moderate exposure to oxygen

facultative anaerobes

grow under aerobic or anaerobic conditions

Microaerophiles

need reduced O2 and increased CO2 for growth

Obligate aerobes

require O2 and do not grow under anaerobic conditions

most common anaerobes category

aerotolerant anaerobes

most common aerobes category

facultative aerobes

normal flora in humans and other animals

endogenous

ecological niches outside the bodies of animals

exogenous

Which source is the most common in anaerobic infections

endogenous infections

How do most anaerobic endogenous infections happen

trauma to skin to mucous membranes

why ar most anaerobic infections polymicrobial

they decrease redox environment where anaerobes live, therefore many organisms can be at the site of infection

Common cause of exogenous infections

from soil or ingestion of contaminated food

Why are aspirated specimens preferred over specimens submitted on swabs

difficult to transfer bacteria for testing and involves too much O2 exposure

Why does the site form which a specimen was collected affects its acceptability

want to the sterile body site because there are too many normal flora aerobes in non sterile sites

factor that has the largest impact on the oxidation-reduction potential of anaerobic media

pH

Anaerobic blood agar (ABAP)

recovery of most anaerobes

Phenylethyl alcohol (PEA)

inhibits facultative anaerobic GNRs and proteus swarming

Supports anaerobic GP & GN organisms

Kanamycin/vancomycin lakes blood (KVLB/LKV)

kanamycin inhibits most of facultative GNRs

Vancomycin inhibits most GPs

Bacteroides Bile Esculin

prevent growth of most organisms and will turn black

Ambient air conditions

21% O2, 0.03 CO2

CO2 conditions

15-21% O2, 5-10% CO2

Microaerophilic conditions

5% O2, 10% CO2

anaerobic conditions

0% O2, 5-10% CO2

Typical catalyst used in anaerobe chamber

palladium coated aluminum pellets

Desiccant used in anaerobe chambers

silica gel

gas mixture in anaerobe chamber

5% H2, 5-10% CO2, and 85-90% N2

Oxidation reductions indicators used in anaerobe chambers

methylene blue or resazurin

importance of incubating anaerobe plates and biochemical for 48hrs

mist susceptible to toxic oxygen within the first 48hrs

lecithinase role in egg yolk agar

cleaves lecithin and release insoluble fat

lipase role in egg yolk agar

hydrolyzes triglycerides and diglycerides to fatty acids and glycerol

Proteolysis role in egg yolk agar

breaks down proteins and form clearing around colonies

most common causative agent of my necrosis/gas gangrene

Clostridium perfingens m

media used for isolation of C. difficile

CCFA

true terminal spores

located at the end

classical subterminal spore

located near the end

What test allows B. fragile group to be divided into two groups

Indole

Organism that is typically found as a contaminant in blood or CSF

S. saccharolyticus

Cutibacterium acnes disease

shunt infections

clostridium tetani disease

tetanus or lock jaw

clostridium septicum disease

colon cancer

clostridium botulinum

floppy baby syndrome, foodborne/wound botulism, food poisoning

clostridium perfingens disease

gas gangrene (myonecrosis), food poisoning (meats and gravy)

Clostridium difficile

pseudomembranous colitis or antibiotic associated diarrhea

Actinomyces disease

actinomycosis or lumpy jaw (sulfur granules)

Mobiluncus disease

bacterial vaginosis

antimicrobial agent

a substance naturally or synthetically produced by living organisms such as bacteria and/or fungi, able to dilute solution to inhibit or kill another microorganism

Antibiotic

tending to prevent, inhibit, or destroy life

Spectrum of activity

range of activity that an antimicrobial agent/antibiotic has against certain groups of bacteria