Microbiology Flashcards
What kind of bacteria does the MacConkey agar stain for?
Gram negative
What is the purpose of the Hektoen enteric agar?
Differentiate salmonella and Shigella
What does mycoplasma require in order to grow?
Needs cholesterol, purines, and pyrimidines because it has a weak membrane
Cholesterol helps to stabilize the cell membrane
Which bacteria need cysteine to grow?
Francisella
Brucella
Legionella
Pastuerella
Which organisms commonly form biofilms?
Staph epidermis
Strep mutans
Pseudomonas
In which phase of bacterial growth do antibiotics work the best in?
The log phase: phase of rapid replication
Which stain can recognize capsules?
India Ink- doesnt always work
What is the toxin of Strep pyogenes? How does she work
M protein: binds to complement and doesnt allow it to work properly (C3b)
What is the toxin of Staph Aureus and how does it work?
Toxin A: binds to the Fc portion of IgG so that it doesnt get targeted
__________ can change its pili and outer membrane proteins as a way of tricking the cell and avoiding destruction (antigenic variation)
Niesseria Gonorrhea
What are two viruses that are WELL KNOWN for antigenic variation
Influenza
HIV
_________ survives by inhibiting phagosome-lysosome fusion
M tuberculosis
_________ survives inside the cell by escaping the phagosome before the phagosome lysosomal fusion
Listeria
What is LPS? Is it found on gram negative or gram positive bacteria?
LPS is found on gram negative bacteria; it consists of O antigen, a core, and a Lipid A molecule
Lipid A is the toxin and binds to phagocytes; released at the death of the cell
What are the bacteria that are encapsulated? At least the larger bacteria?
Strep pneumo Klebsiella H flu Pseudomonas Aeruginosa N. meningitidis Cryptococcus neoformans
Some Killers Have Pretty Nice Capsules
________ is the primary virulence factor in gram negative septic shock
LPS
What is the mode of action of the diphtheria toxin?
ADP ribosyl transferase inactivates eEF2 which inhibits eukaryotic cell protein synthesis
Targets the heart, nerves, and epithelium
What is the toxin of pseudomonas aeruginosa?
Exotoxin A: ADP ribosyl transferase inactivates eEF2 which inhibits eukaryotic cell protein synthesis
Which two bacteria have toxins that interfere with the 60S ribosomal subunit?
Shigella toxin and Verotoxin (EHEC)
Which toxin blocks the release of GABA as an inhibitory transmitter to ACH, causing a spastic paralysis?
Tetanus toxin
Which toxin blocks the release of ACh leading to a flaccid paralysis?
Botullinum toxin
In what two infections is a cAMP cascade induced?
Enterotoxigenic E coli
Vibrio cholerae
When cAMP is increased in the intestines what happens?
Water follows leading to profuse watery diarrhea
What are the components of the anthrax toxin?
EF= edema factor
LF=lethal factor
PA=protective antigen
What two toxin affect the Gi protein?
Bacillus anthracis
Bordetella pertussis
Alpha toxin of Clostridium perfringens uses __________ to damage cell membranes and myonecrosis?
Lecithinase
A 27 year old male comes into the ED with a fever and malaise. He reports a hx of IV drug use. Chest exam reveals a new murmur. Where would this organism be found in a healthy person as a part of normal flora?
Staph aureus infective endocarditis
Lives in the nose and skin
A number of people become ill following a picnic with GI infection. Most of the patients had symptoms appear within 2-6 hours of eating the food. Sx included diarrhea, vomiting, and abdominal pain. If the food were laid on an agar, what shape would you expect any bacteria to be?
Gram postive cocci in clusters
What are the spreading factors of strep pyogenes?
Streptokinase: breaks down the fibrin clots which allows for the bacteria to travel throughout the body
Streptococcal DNAse: liquifies pus
Hyaluronidase: hydrolyzes ground substance of connective tissue
A 2 day old infant in the NICU develops a fever, respiratory distress, high white count with high neutrophil count. Per medical history, the mother was in labor for 2 days secondary to anesthesia allergy and inability to operate via Csection. What is the most likely causative organism?
Baby has sepsis
Caused by group B strep
Name that bacteria Alpha hemolytic Optochin sensitive Lancet shaped bacteria Lysed by bile
Strep pneumo
A 16 yo male presents to the ED following a car accident. The patient did not have his seatbelt on and was thrown from the vehicle. He undergoes a STAT splenectomy secondary to a splenic laceration. When he is in recovery, the parents are asking what they need to know regarding the patients new condition- what do you tell them?
That he is at risk for encapsulated bacterial infections
_________ is the most common cause of adult pneumonia
Strep pneumo
