Keywords: 1-8 Flashcards
1 PCR
Primer recognition of known viral or bacterial genetic sequences
1 Colonizers associated w/ disease states:
Viridans streptococci
HACEK
Fusobacterium spp.
Neisseria meningitidis
Candida albicans
Endocarditis
Endocarditis
Bacteremias
Meningitis
Thrush
1 Types of Cultures (3)
Qualitative: negative or positive
Semi-quantitative: negative, rare, light, moderate, or heavy growth
Quantitative: colony-forming units (CFU) per volume
1 Blood Culture Contamination
Blood should be collected from two different sites. Blood from each site is collected in 2 bottles; one to support aeroob growth and another to support anaeroob growth. Since the skin is covered by organisms, improperly collected blood cultures may be contaminated with bacteria such as coagulase negative staphylococci. Two samplings (2 sets of 2 bottles each) may differentiate between contamination and a true bacteremia. It is more useful to report the amount of positive sets than amount of positive bottles.
1 Detection of Antibodies (Serology)
Detection of antibodies (serology) against bacteria, fungi, viruses or parasites.
IgM production may not be apparent at the time of the patient presenting to
physicians; a “convalescent” sample (collected 10-14 days after presentation)
should be collected to detect late-occurring IgM and also changes in IgG titer.
1 Urine Collection Inflammation vs. Contamination
White blood cells –> inflammation
Epithelial cells –> contamination
> 100,000 bacteria/mL –> infection
Polymicrobial growth –> contamination
1 Respiratory Tract Secretion Contamination
Broncho-Alveolar Lavage (BAL) makes contamination less likely than a sputum culture
2 Virulence Factors
What the micro-organisms use to cause disease
Toxins: poisons made by micro-organisms that affect/infect the host
Adhesins: molecules that a pathogen uses to attach to host tissues or host cells
Capsules: molecules that help a micro-organism have anti-phagocytic properties
2 Virulence
The number of organisms it takes to start an infection
LD50: # of organisms you have to inoculate into an animal to kill 50% of the animals
ID50: # of organisms you have to inoculate into an animal to make 50% of the animals sick
ED50: # of organisms you have to inoculate into an animal to induce an effect (ex. fever) in 50% of the animals
2 Facultative vs. Obligate Intracellular Pathogens
Facultative: Can grow inside or outside host cells
Obligate: Have to have host cells or can’t replicate
3 Prokaryotes
No nucleus
Mainly bacteria
3 Bacteria:
Cells (y/n)
Nucleic Acid(s)
Ribosomes
Mitochondria (y/n)
Cell Wall Component
Motility
Binary Fission (y/n)
Yes
DNA & RNA
70S
No
Peptidoglycan (exceptions: Mycoplasma & Chlamydiae)
Some (cocci no, rods maybe, spirochetes yes)
Yes
3 Fungi:
Cells (y/n)
Nucleic Acid(s)
Ribosomes
Mitochondria (y/n)
Cell Wall Component
Motility
Binary Fission (y/n)
Yes
DNA & RNA
80S
Yes
Chitin
No
Yes
3 Parasites:
Cells (y/n)
Nucleic Acid(s)
Ribosomes
Mitochondria (y/n)
Cell Wall Component
Motility
Binary Fission (y/n)
Yes
DNA & RNA
80S
Yes
No
Usually
Yes
3 Peptidoglycan Crosslinking
Carried out by transpeptidases (aka penicillin binding proteins, PBPs)