Week 7 Flashcards
How Streptococci appear on Gram stain?
They appear as gram-positive (purple) cocci chains or in pairs.
Would the catalase test be useful when distinguishing between Strep and Staph?
Yes! Strep is catalase negative.
This test is used to differentiate Beta-hemolytic Streptococcus into groups A and B. What is the test?
Bacitracin Sensitivity test
To remember what the Bacitracin sensitivity test isolates: B-BRAS stands for what?
Bacitracin: group B strep are Resistant; group A strep are Sensitive
This test is a chemical used in cell culture techniques to discriminate S. pneumonia from other alpha-hemolytic streptococci. What is the test?
Optochin test
To remember what the optochin test isolates: what is OVRPS?
(overpass) Optochin: Viridans are Resistant; Pneumoniae are Sensitive
Strep can be found where in/on the body?
Nasopharynx, oral cavity, skin and vagina.
One of S. pyogenes’ virulence factors utilizes the __ protein to inhibit ______ and _______ by blocking complement.
M protein
Opsonization and phagocytosis
________ converts plasminogen to _____ and results in fibrinolysis that aids in the spread of S. pyogenes through adjacent tissues.
Streptokinase
Plasmin
____ is another name for S. pyogenes.
GAS
Necrotizing fasciitis is a rapidly progressive infection of the _____.
Deep fascia
S. pneumoniae’s most important virulence factor is having a ____.
Capsule
Another virulence factor of S. pneumoniae aids in bacterial spread by cleaving secretory ____, which is present in mucus.
IgA
S. pneumoniae is _______(type of hemolysis) and secretes an exotoxin known as ______.
Alpha-hemolytic
Pneumolysin
The presence of a capsule allows strep to spread systemically and even cross the _________.
Blood brain barrier
_______, is most commonly transmitted via the birth canal, and is a common cause of many neonatal infections.
S. agalactiae AKA (GBS)
Pneumonia is often treated with either a _____ and will almost always get an IV third-generation _____.
Macrolide
Cephalosporin
Treatments for most other infections caused by strep species involve penicillins like _______ and _______.
Amoxicillin and penicillin G
How does V. cholerae cause a massive watery diarrhea?
V. cholerae produces cholera toxin, which increases the intracellular concentration of cAMP (because Gs cannot be turned off) in intestinal cells and enhances NaCl secretion, which also inhibits water reabsorption.
The diarrhea associated with V. cholerae is described as “_____” stools due to its consistency of water and white chunks of ____.
Rice-water
mucus
Why is rehydration in V. cholerae infections important?
Fluid secretion results in a massive loss of fluid, sodium, chloride, and bicarbonate. This loss of fluid can result in hypovolemic shock.
What is the difference between antibiotics and antibacterials?
Antibiotics, better known as antimicrobials, include those meds target fungi, archaea, parasites, and bacteria, whereas antibacterials target bacteria specifically.
What are the three general mechanisms used by antibacterial agents?
Generally, inhibiting cell wall or membrane synthesis, inhibiting DNA and/RNA synthesis, or inhibiting protein synthesis.
What do each of these meds inhibit within the bacterial cell?
1) Vancomycin/Bacitracin:
2) Amoxicillin:
3) Tetracyclines and Gentamycin/Tobramycin:
4) Chloramphenicol, Macrolides (Erythromycin):
5) Ciprofloxacin:
6) Rifampin:
7) Sulfonamides:
1) Peptidoglycan synthesis
2) Peptidoglycan cross-linking
3) 30S subunit ribsome
4) Protein synthesis
5) Gyrase (DNA gyrase)
6) mRNA synthesis (RNA polymerase)
7) Folic acid synthesis and reduction (DNA methylation)
______/______ inhibit bacterial topoisomerase leading to DNA damage.
Quinlones/Fluoroquinolones
What is the terminology used to describe the antibacterial therapy that may be initiated before knowing the culprit organism?
Empirical treatment describes the treatment.
Penicillin structure consists of a ____ ring fused to a thiazolidine ring.
Beta-lactam
What is the structure of penicillins?
A Beta-lactam ring is the core structure of penicillins and all Beta-lactam antibiotics.
Beta-lactam binds _____ to transpeptidase (Penicillin binding protein) enzyme, that cross-links the linear peptidoglycan chain components of the cell wall.
Noncompetitively (irreversibly)
What happens to host cells with Penicillin? Are they damaged too?
No, because human cells do not have cell walls, neither make or need peptidoglycan.
One minor mechanism of resistance is the presence of mutations in ______, leading to structural changes such that the antibiotic no longer binds.
Penicillin binding proteins (PBPs)
What is the main bacterial mechanism of resistance against a penicillin antibiotic?
The production of Beta-lactamase (penicillinase). Others includes mutations in PBPs and structural changes in the bacterial outer membrane.
What are some of the drugs used to protect penicillin from being destroyed by Beta-lactamases?
Beta-lactamase inhibitors! Given in combo with penicillins.
Clavulanic acid, sulbactam, and tazobactam.
Antibiotic-associated colitis caused by ______ may occur during or immediately after therapy with a penicillin.
Clostridioides difficile
_______ antibiotics can interact with the A, P, and E sites or other parts of the ribosome to inhibit or kill bacteria.
Protein synthesis inhibitor (PSI)
Are tetracyclines considered bacteriostatic or bactericidal?
Bactiostatic because their MOA is restricted to only halting protein synthesis, which does not cause bacterial death.
What rRNAs on the 50S subunit do most 50S RIAs bind to?
Common site of action for chloramphenicol, macrolides, clindamycin, and streptogramins is 23s rRNA (contains peptidyl transferase which has a pivotal role in protein synthesis making it a valuable target for antibiotics)
Which resistance mechanism is most applicable to aminoglycosides?
Enzymatic inactivation. Like Health care-associated bacteria have been known to develop enzymes that inactivate aminoglycosides through acylation.
Bacteria can actively transport protein synthesis inhibitors out of their cytoplasm to reduce antibiotic activity. These are called what?
Efflux pumps
_____ syndrome is specific to chloramphenicol and is potentially fatal and characteristically presents with hypotension and cyanosis.
Gray baby syndrome
For Aminoglycosides: Protein mistranslation can produce abnormal, nonfunctional ribosomes, causing irreversible inhibition and ______.
bacterial death
Name a Rickettsia rickettsi treatment and type of lab test to confirm.
Doxycycline
Serology and PCR (For non-gram staining bacteria)
Out of all the non-gram staining bacteria, which is a sprirochete?
Borrelia burgdoferi
What is a slow growing disease, where you need to treat with dapsone, rifampin, and clofazamine?
Mycobacterium leprae
Which bacteria will you often see MRSA, TSS, food poisoning, and many more?
S. aureus
Which bacteria’s toxin causes the disease manifested but not the bacteria itself, and is anaerobic?
C. tetani
What is the shape of Streptococcus pyogenes?
Cocci, chains
What is the bacteria that presents with impetigo, pustular crusty rash, and can be treated with Penicillin G?
Streptococcus pyogenes
Which Gram negative bacteria uses the Thayer Martin test?
Neisseria meningitidis
Perhaps Thayer Martin is also the maltose fermentation test.
Which bacteria is a coccobacilli and needs factors X and V, and treated with Rifampin prophylaxis and Hib vaccine?
Haemophilus influenza-b
What bacteria gives a green culture, and must be treated with anti-pseudomonas penicillin and aminoglycoside?
Pseudomonas aeruginosa
E. coli can be treated with ____ and _____.
TMP-SMX
PCN
Which does NOT cause UTI?
E. coli
Pseudomonas aeruginosa
Mycoplasma pneumoniae
Mycoplasma pneumoniae
Which bacteria causes Lyme Disease?
Borrelia burgdoferi
What bacteria needs to be treated with MRSA vancomycin?
S. aureus
What is gram positive and anaerobic, associated with a vaccine as well?
Clostridium tetani
Vaccine is Tdap
Which of the bacteria tests positive for Bacitracin sensitivity? Is it gram positive or gram negative?
B-BRAS
Group A Lancefield is Sensitive, which includes S. pyogenes.
It is gram positive
Is V. cholerae oxidase positive or negative?
Oxidase positive
What is the reason why Rickettsia rickettsi cannot be stained?
It is an intracellular bacteria
What is the reason why M. leprae cannot be stained?
It has a waxy surface
Which bacteria has no cell wall?
M. pneumoniae
What is the mechanism for Doxycycline, and what diseases does it usually treat?
Doxycycline inhibits the 30S ribosomal subunit, so translation cannot occur within the bacterial cell. It will usually treat Rickettsia rickettsi and Borrelia burgdoferi
In treating S. aureus, we use MRSA vancomycin, what is its mechanism and does it have a Beta-lactam ring association?
Vancomycin works against cell wall synthesis, mostly against peptidoglycan synthesis. It does NOT have a beta-lactam ring.
How would you treat someone who presents with chain appearing cocci, with TSS, and impetigo?
Penicillin G (natural PCN)
What does coagulase do? What is its substrate and product?
Coagulase converts fibrinogen to fibrin, and serves as a coat. Normally will thicken the sample.
