B3-003 Prework 1 Intro to Lab Diagnosis Culture Flashcards
What are Koch’s postulates
- Microorganism present in every case of the infectious disease
- Microorganism can be isolated in pure culture
- Inoculation of pure culture into animals produces similar disease
- Same species of micro organism recovered from diseased animal
What are the arrangements of spherical bacterial cells
Diplococcus
Tetrad
Streptococcus
Staphylococcus
What feature of gram negative bacterial cell wall is an endotoxin
Lipopolysaccharide –> shock
In a gram stain what happens to gram positive bacteria
they stain violet
In a gram stain what happens to gram negative
it stains pink
What is an obligate aerobe
requires oxygen for growth
What is facultative anaerobe
will grow in aerobic and anaerobic conditions
What is microaerophilic
grows best with low concentrations of oxygen
What is obligate anaerobe
Oxygen is toxic
What are fermenters
Fermentation of glucose and lactose used to characterize organisms
How do you measure fermentation
Byproducts - Lactic acid, butric acid, mixed acids
When your patient has an infection what are the diagnostic tests you can choose from
microscopy, culture, serology, molecular biology
What is molecular biology
nucleic acid detection
Sputum specimen is from
lower respiratory tract
What are the normal bacterial flora of upper respiratory tract
Staph sp. Strep sp. - Strep pneumoniae - Viridans strep Haemophilus sp Anaerobes
What is the normal bacterial flora of the skin
Staph sp
Coryneform bacteria or diptheroids
Propionibacterium sp
What is the normal bacterial flora of the GI tract
anaerobes enterococcus sp enterobacteriaceae Enterobacteriaceae - Escherichia coli - klebsiella sp Strep anginosus Lactobacillus sp candida sp
What are the normal flora of the Genital tract
Lactobacillus sp
Strep agalactiae
what types of specimens do you use direct gram stain
sputum, positive blood culture, abscess fluid, CSF, vaginal discharge
What is an enriched culture
contains nutrients to support growth of a wide variety of organisms
What is a selective culture
inhibits growth of certain groups of organisms
What is a differential
distinguish organisms based on growth characteristics
What are key concepts of blood cultures
Draw before antibiotics
Fill bottles
What is a viral culture grown with
mammalian cells
What type of hemolysis is green and shows incomplete lysis around a colony
alpha
What type of hemolysis has a clear zone around the colony
beta
What type of hemolysis has no hemolysis
gamma
What organism produces a yellow pigment on a blood agar
Staphylococcus aureus
What organism grows red/pink colonies
Serratia marcascens
What organism grows green/blue colonies
Pseudomonas aeruginosa
What are the colony characteristics of Klebsiella pneumoniae
mucoid
What are the colony characteristics of candida albicans
Projections
What are the colony characteristics of proteus vulgaris
Swarming
What are 3 enzymatic tests
Catalase
Coagulase
Oxidase
What organisms exhibit alpha hemolysis
S. Pneumoniae
S. Mutans
Viridans group
What organisms exhibit beta hemolysis
S. Pyogenes (GAS)
S. agalactiae (GBS)
what is an organism that exhibits gamma hemolysis
enterococcus
what types of antimicrobial susceptibility testing are there
Genotypic - PCR based detection of the genes associated with resistance to a drug
Phenotypic - tests ability of organism to grow in presence of drug
What are advantages of PCR based detection of genes associated with resistance to drug
Fast
Very sensitive
Very specific
What are limitations of PCR
Expensive
Single target
What are examples of phenotypic susceptibility testing
MIC Agar dilution Broth microdilution Disk diffusion Strip (Etest)
