First Aid: Microbiology Flashcards
(38 cards)
What sort of response does Lipoteichoic Acid (gram+ cell wall) and Lipid A (g- outer membrane) induce?
TNF and IL1
What is the periplasm of a bacterium and what is unique about this structure?
Space between cytoplasmic membrane and outer membrane in g- bacteria
Contains many hydrolytic enzymes, ilncuding beta-lactamases
What is unique about the structure of mycoplasma and mycobacteria?
Mycoplasma - membrane contains sterols and no cell wall
Mycobacteria - contain mycolic acid and HIGH lipid content - acid fast staining
What are the major gram + bacteria?
Circular - Staphylococcus, Streptococcus
Rods - Clostridium, Corynebacterium, Bacillus, Listeria, Mycobacterium (acid fast), Gardnerella (gram variable)
Branching Filamentous - Actinomyces, Nocardia (weakly acid fast)
Which microbes do not gram stain well and why?
These Microbes May Lack Real Color
Treponema (too thin for visualization)
Mycobacteria (hihg lipid content, use acid fast-carbol fuchsin stain)
Mycoplasma (no cell wall)
Legionella pneumophila (primarily intracellular)
Rickettsia (intracellular parasite)
Chlamydia (intracellular parasite; lacks muramic acid in cell wall)
When is a Giemsa stain useful?
Certain Bugs Really Try my Patience
Chlamydia, Borrelia, Rickettsiae, Trypanosomes, Plasmodium
When would a PAS (periodic acid-Schiff) stain be helpful?
Whipple Disease (Tropheryma whipplei)- because PAS stains glycogen, mucopolysaccharides
PASs the SUGAR
What is silver stain useful for identifying?
Fungi (pneumocystis), Legionella, H. Pylori
Match the bacteria with the media culture used
Page 122 First Aid
What aerobic bacteria can often be found in burn wounds, complications of diabetes, nosocomial pneumonia, and pneumonias in cystic fibrosis patients?
Pseudomonas aeruginosa
What are two situations that could lead to reactivation of TB, and what lung areas would be affected?
Immune compromisation or TNF-alpha inhibitor use
Predilection for apices of lung (highest PO2)
What are the main obligate aerobes?
Nagging Pests Must Breathe
Nocardia, Pseudomonas aeruginosa, MycoBacterium tuberculosis
You discover foul smelling bacteria that are difficult to culture and produce gas (CO2 and H2) in tissues. What are some main possibilities as to the identity of this bug and what makes them unique?
Obligate Anaerobes - Cant Breathe Air
-Clostridium, Bacteroides, Actinomyces
Lack catalase and/or superoxide dismutase –> susceptible to oxidative damage
What are the obligate intracellular bugs and facultative intracellular bugs?
Stay inside cells when it’s Really Cold –> Rickettsia, Chlamydia (can’t make own ATP)
Some Nasty Bugs May Live FacultativeLY
Salmonella, Neisseria, Brucella, Mycobacterium, Listeria, Francisella, Legionella, Yersinia pestis
Which bacteria have capsules that serve as an antiphagocytic virulence factor?
SHiNE SKiS
Streptococcus pneumoniae, Haemophilus influenzae type B, Neisseria meningitidis, Escherichia coli, Salmonella, Klebsiella pneumoniae, and group b Strep
How does the body get rid of encapsulated organisms and what considerations do you have to take in compromised patients?
Opsonized and cleared by spleen
Asplenics are at risk of infection so give prophylactic vaccines for Strep pneumo (PCV, PPSV, Pneumovax), H Flu (type B conjugate vaccine), and N. meningitidis (Meningococcal conjugate vaccine)
Which organisms are catalase positive and what patients are at risk for recurrent infections with catalase + organisms?
youu need PLACESS for your cats
Pseudomonas, Listeria, Aspergillus, Candida, E. coli, S. aureus, Serratia
People with chronic granulomatous disease (NADPH oxidase deficiency)
What are the urease positive bugs?
CHuck norris hates PUNKSS
Cryptococcus, H plyori, Proteus, Ureaplasma, Nocardia, Klebsiella, S epidermidis, S saprophyticus
A bacteria is found to produce yellow sulfur granules composed of filaments of bacteria, what could be the origin?
Yellow Pigment? Blue-Green pigment? Red pigment?
Actionmyces israelii (israel has yellow sand)
S. Aureus (aureus = gold, yellow) Pseudomonas aeruginosa (Aerugula is green) Serratia marcescens (red maraschino cherries)
What enzyme is secreted by S. pneumo, H flu and Neisseria that allows them to colonize respiratory mucosa?
IgA protease
What do virulence factors “Protein A” and “M protein” cause in the host? Which bacteria release each?
Protein A - Binds Fc region of IgG, prevents opsonization and phagocytosis (S. Aureus)
M protein - helps prevent phagocytosis (group A strep)
A patient presents with fever, hypotension and DIC. A toxin is isolated that is found to be stable at 100 degrees C and induces TNF, IL1 and IL6. What is the origin of this toxin?
Endotoxin - outer cell membrane of most gram - bacteria
Lipopolysaccharide (structural bacteria part, released when lysed)
What are the 9 key features of ENDOTOXIN?
Edema
Nitric Oxide release from active macrophages
DIC/Death from a
What do novobiocin, optochin, and bacitracin help differentiate among the gram + cocci?
“On the office’s STAPH retreat, there was NO StRESs”
-STAPHylococci –> Novobiocin –> Saprophyticus is Resistant; Epidermidis is Sensitive
Strep:
OVRPS (overpass) –> Optochin - Viridans is Resistant; Pneumoniae is Sensitive
B-BRAS –> Bacitracin - group B strep are Resistant; group A strep are sensitive
