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Neisseriaceae and Antimicrobial Susceptibility Testing
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45
Microbiology
Undergraduate 3
04/05/2015

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Term
Neisseriaceae
Definition
Gram neg diplococci.
Inhabit the mucous membranes of warm-blooded hosts.
non-motile and non-spore forming.
Grows in CO2
Term
Neisseriaceae are catalse what? Oxidase what?
Definition
Cat-Pos
Ox-Pos
Term
Neisseria gonorrhoeae causes what in males?
Definition
Urethritis
Dyuria
Urethral discharge
Term
Neisseria gonorrhoeae causes what in females?
Definition
Endocervix infection, symptoms include: cervicovaginal discharge, lower ab pain, abnormal periods
Term
What are some populations with a high prevalence of neisseria gonorrhoeae?
Definition
Low socioeconimic class
Residence in urban areas
Drug abuse
Prostitute
Term
Lab identification of Neisseria gonorrhoeae?
Definition
Grows in translucent, raised, moist, grayish-white colinies on CHOC or MTN agar.
Produces bubbles to superoxol
Can be identified usingMolecular probe technology
Term
MTM agar
Definition
Selective media for Neisseria
Contains:
Vancomycin- Inhibits gram pos
Colistin- Inhibits gram neg
Nystatin- Inhibits yeasts
Trimethylprym- Inhibits flagellar action of proteus. (Prevents from swarming)
Term
Neisseria gonorrhoeae carbohydrate test and enzyme test
Definition
Carb test- Only glucose pos
Enzyme test- Hydroxypropyl aminopeptidase positive
Term
What is the standard for diagnosis of Neisseria gonorrhoeae?
Definition
Culture
Term
Neisseria meningiditis symptoms:
Definition
Confusion, headache, fever.
Causes petechiae which are small hemorrhagic skin lesions
Term
Neisseria meningiditis acute form
Definition
Slight fever, respiratory tract symptoms
Term
Neisseria meningiditis chronic form
Definition
Fever, rash, arthritis
Term
Spread of Neisseria meningiditis
Definition
Spread by respiratory droplets or direct contact with respiratory secretions. Humans are the only host.
Term
Lab identification of Neisseria meningiditis
Definition
The presence of inflammatory cells has prognostic value (with fulminant, rapidly fatal disease, many organisms are seem with few inflammatory cells)
Colony on CHOC agar and MTM agar is similar to N. gonorrhoeae.
Will grow on blood agar.
Term
Direct antigen detection
Definition
Test used to identify Neisseria meningiditis. Performed to identify meningococcal capsular polysaccharides. Pos test is helpful for early diagnosis. Neg test does not rule out meningitis caused by other organisms.
Term
Neisseria meningiditis carbohydrate and enzyme test results
Definition
Carb- Glucose and maltose positive
Enzyme- Gamma glutamylaminopeptidase positive
Term
Neisseria species are normal flora of the
Definition
Human respiratory tract
Term
N. subflava, N. mucosa, N. sicca and N. flavescens may cause what?
Definition
Endocarditis in patients with prosthetic heart valves or IVDA
Term
N. lactamica
Definition
Can grow on selective media. Isolated from genital sites, CSF and blood
Term
Lab results for other Neisseria spp.
Definition
Carb test- Glucose, lactose and maltose pos
Enzyme test- beta-D-galactosidase
ONPG-hydrolyzed
Term
N. cinera
Definition
Recovered from patients with AIDS as a cause of nosocomial pneumonia. Grows on BAP and CHOC
Term
N. cinera carb test and enzyme test
Definition
Carb- No production of acid from carbs in the CTA-based or rapid carb tests. Weakly pos glucose has been reported for some automated systems.
Enzyme test- Pos for hydroxypropyl aminopeptidase
Term
Colistin disk susceptibility test
Definition
Can differentiate N. cinera from N. gonorrhoeae.
N cinera= S. N gonorrhoae= R
Term
Only rod-shaped member of the genus Neisseria?
Definition
N. elongata
Term
Moeraxella catarrhalis
Definition
May cause lower respiratory tract infection in older people or those with chronic disease.
Also causes otitis media and acute sinitis in children
Term
Opthalmia neonatorum
Definition
Acquired through the acquisition of Moraxella catarrhalis at birth from the mother's colonized genital tract.
Term
Lab identification of Moraxella catarrhalis
Definition
Grows on BAP and CHOC. Slides on agar.
Carb test: assacharolytic
Enzyme test: Neg for all enzymes tested.
DNase: positive
Chromogenic cephalosporin test: posive (Production of an inducible, cell-associated beta-lactamase)
Term
B. Cat disk
Definition
Quick spot test used to identify Moraxella catarrhalis. The organism hydrolyzes the ester-linked butyrate in disk to produce a color change.
Term
MIC
Definition
The minimum amount of antibiotics that can be used to inhibit the spread of an organism.
Term
Bacteriocidal
Definition
Kills bacteria
Term
Bacteriostatic
Definition
Prevents organism from growing.
Term
Procedure for an MIC
Definition
Set up serial dilution with antimicrobial agent to determine which of the concentrations is the least concentration which prevents the organism from growing. To find the correct tube. Find the first tube in which the organism appears not to be growing
Term
MBC
Definition
The minimum concentration of anitbiotic that will kill a specific microorganism.
Term
Procedure for MBC
Definition
After performing a serial dilution with a specific organism and antibioticm, quantitatively subculture all clear wells to determine what the minimum concentration of antibiotic is that will kill the organism
Term
Which is larger: The bacteriocidal concentration or the bacteriostatic concentration?
Definition
The bacteriocidal concentration
Term
Is it possible to perform an MBC on a cidal agent?
Definition
Yes
Term
Is it possible to perform an MBC on a static agent?
Definition
No because the agent will only prevent the organism from growing, not kill it
Term
Schlicter Test
Definition
Involves using patient serum which is tested against a certain bacteria to see if it will kill it.
Term
What are some things that are important to standardize in antimicrobial testing?
Definition
Conc of agent
Conc of organism
Standardized McFarland inoculation
Size of disk
Plate thickness
How far apart discs are
Incubation time
Standardized zone of clearing
Incubation temp
Manufacture consistency
Term
Kirby-Bauer Susceptibility Test
Definition
A method to determine the sensitivity of microorganisms to specific antimicrobial drugs; greater drug efficacy yields larger microbe-free zones surrounding drug-containing disks after overnight growth on solid media. (MIC Test)
Term
E-Test
Definition
Quantitative technique for determining the antimicrobial susceptibility of microorganisms (MIC Test)
Term
How can you get a falsely resistant MIC?
Definition
Not enough antibiotic
Too much organism
Term
How can you get a falsely susceptible MIC?
Definition
Too few organisms in tubes
Too much antibiotics in tubes
Dilution is off
Term
Set up a normal MIC using serial dilution
Definition
1. Make serial dilution by dividing each preceeding tube concentration by 2. (Take tube 1 conc and divide it in half and repeat)
2. Add TSB or Mueller-Hinton broth to each test tube
3. Add necessary amount of antibiotic to the first tube. Transfer the same amount of solution into the next tube and repeat for all tubes.
4. Need a growth control (no antibiotic)
5. Need a sterility control (no organism)
Term
Determine a normal MBC
Definition
1. Inoculate a plate for each clear tube that was present. Streak to obtain a colony count.
2. Incubate plates
3. Examine the plates for presence of growth of test organism.
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