Viro/bacteria exam 1 Flashcards
Streptococci
Chains of spheres
e.g. Streptococcus (G+)
Staphylococci
Grape-like/Irregular clusters Gram (+)
e.g. Staphylococcus
Coccobacilius
Short and plump rods
ex. Haemophilus (G-)
Fusiform
Rods with tapered ends
eg. fusobacterim (G-) often normal flor in oral cavity
Diplococci
Paired spheres G (-)
e.g. Neisseriea
coryneform
Club shaped rods
e.g. Corynebacterium (G+), diptheria
Vibrio
Comma shaped, gently curved
eg Vibrio Cholera (G-),
Spirochete
Spiral form
e.g. Treponema pallidum (G-), Syphilis
Leptospira
Tightly wound spirals
e.g. Leptospira (G-)
Borrelia
Very tightly wound spirals
e.g. Borrelia (G-)
E. Coli
O157:H7
Penicillin has 3 parts and what is its mode of action
-only active during the log phase (growth phase)
all end with “cillin”
Thiazolidine ring, beta-lactam ring and R group.
-The beta lactam ring interacts with transpeptidases (preventing the synthesis of peptidoglycan)
Beta-lactamase inhibitors produced by bacteria to inhibit penicillin
-Clavulanate + amoxicillin = augmentin and clavulanate + ticarcillin = timentin (beta-lactmase inhibitors + penicillin)
What 2 penicillin drugs are penicillinase resistant?
Methcillin and nafcillin
Cephalosporins
-most are resistant to penicillinases
Similar to penicillins, less allergic reactions.
-Same mechanism of action (beta-lactam)
-can be administered IV or injection
- drugs begin with “cef” or “ceph”
Cephalosporins are broad spectrum and can cause super-infections
Other beta-lactams and what do they do?
Imipenem and Aztreonam
They shut down the formation of NAG and NAM
Isoniazid
Targets cell wall of tuberculosis.
-bacitracin also targets the cell wall
Polymyxin
Narrow spectrum antibiotics, due to toxicity to kidney
-disrupts cell membrane function by inserting its tail into the membrane
polymyxin MIXES up the cell membrane
Quinolones
Inhibit DNA topoisomerases (gyrases)
- Fluoroquinolones are broad “spectrum” and can inhibit both gram + and gram -
e. gs Ciprofloxacin and norfloxacin (all the floxacins)
Rifamycin
what is it used for TQ***
Inhibits DNA-dependent RNA polymerase by preventing RNA synthesis
- used for gram + rods and coccus TB and leprosy
- used for mycobacterial infections
Metronidazole mode of action and who it works against
TQ
It uses a free radical (nitrogen) that damages bacterial DNA
-works against anaerobic bacteria
What is the mode of action of Aminoglycosides, tetracylines, macrolides, chloramphenicol, clindamycin, streprogramin and oxazolidones?
Block protein synthesis by reacting with the ribosome-mRNA complex.
Name the aminoglycosides
-end in cin (mins the floxacins)
Streptomycin,neomycin,kanamycin,gentamycin,toramycin,
amikacin,spectinomycin
Name the tetracylines
end in cycline
-Tetracycline, doxycycline, minocycline
Why is chloramphenicol not used in the U.S.?
Very toxic to human cells. Use is restricted to typhoid fever*
Why is synercid?
A streptogramin. effective against staphylococcus and enterococcus and streptococcus
What is linezolid?
It is an oxazolidone. used to treat MRSA and VRE the two most difficult pathogens
Mode of action of sulfonamide and trimethoprim?
Inhibit folic acid synthesis.
- Sulfonamides prevent PABA conversion to dihydrofolic acid
- Trimethoprim inhibits dihydrofolic acid conversion to tetrahydrofolic acid
- Communly used in combination against UTIs
Which bacteria are penicillinase producing?
-drug resistantance
Staphylococcus aureus and neisseria gonorrhoeae (PPNG)
How can a microbe become drug resistant?
1) drug inactivation (beta-lactamases inactivate penicillin)
2) decreased drug permeability or increased drug elimination
3) Change drug receptor (eg erythromycin alteration of the 50S ribosomal binding site)
4) Change in metabolic patters-develop alternate pathways or enzymes, eg folic acid synthesis
Approaches to antimicrobial therapy
- iron-scavenging capabilities (eg staphylococcus aureus)
- riboswitches - inhibitors of translation
- probiotics - prebiotics encourage growth of good bacteria
- Iantibiotics -antibiotics (short peptides) made by bacteria to disrupt the cell wall/membrane
What Abx are used for colitis?
Overgrowth of C. diff due to use of tetracyclines, clindamycin, and broad spectrum penicillins and cephalosporins.
