Microbiology Flashcards
(45 cards)
Name 2 antibiotics that interfere with folic acid metabolism
. Trimethoprim
• sulfonamides
Name 2 antibiotics that interfere with cell wall synthesis
• Beta lactaMs
• glycopeptides
Also: lysozyme, cycloserine, bacitracin
Name 5 types beta lactaMs
• Penicillin
• beta lactam - beta/ lactamase inhibitor combinations
• cephalosporins
• carbapenems
• monobactams
Name 5 types penicillins with examples
• Natural penicillins: penicillin g, vk (narrow spectrum, primarily G +)
• beta lactamase resistant: methicillin, oxacillin, cloxacillin (staphylococci)
• amino penicillins semi synthetic: ampicillin, amoxicillin (broad spectrum)
• carboxy penicillins
• ureido penicillins: carbenicillin, piperacillin (pseudomonas)
How are bacteria resistant to penicillins? (2)
Enzymatic degradation
• G +: penicillinases
• G - : beta lactamases (tem-1 /shV-1)
Name 4 beta-lactam-beta /lactamase inhibitor combinations
• Augmentin: co- amoxicillin - clavulanic acid!
. PiperaCillin: tazobactam !
• ticarcillin: clavulanic
• ampicillin: sulbactam
Name 3 second generation cefalosporins
• Cefoxitin!
• cefuroxime
• cefamandole
Which antibiotics have the broadest antimicrobial spectrum and are beta lactamase stable
CarbapenemS
Name 2 glycopeptides antibiotics and moa
• Vancomycin
• teicoplanin
- Interfere with cell wall synthesis by binding to terminal d-ala-d-ala (only G + bc large molecules that they can’t penetrate )
Name a side effect of glycopepticles
Nephrotoxic
Which antibiotics are cell membrane inhibitors and what is their spectrum of activity
Polymyxin’s
Used as last resort for multi drug resistant bacteria (neuro and nephrotoxic): acinetobacter baumanii, pseudomonas aeruginosa, carbapenemase producing enterobacteriaçae (cre)
Nb no gram positive or anaerobic cover
Name 2 inhibitors of folate (nucleic acid) synthesis and use
• Sulfonamides: sulfamethoxazole (bacteriostatic, )
• trimethoprim
( usually used together for UTI, pneumocystis pneumonia, drug prophylax in HIV)
Name 3 side effects sulfonamides
• Fever, rashes! Photosensitive, bone narrow suppress
• Steven Johnson syndrome!,erythema multiforme
• toxic epidermal necrolysis
Name 2 antibiotic inhibitors of DNA (nucleic acid) synthesis
• Quinolones:
-1st gen- nalidixic acid (G-)
-2nd gen - fluoro quinolones: ciprofloxacin (G-, g+, excellent pseudomonas)
-3rd gen - levo floxacin
-4th gen: trovafloxaCin
• metronidazole
Name antibiotic inhibitors of m RNA (nucleic acid) synthesis
Rifampicin
Name 3 contraindications and side effects fluoroquinolones
Contraindications
• pregnancy
• children - damage growing bone and cartilage
Side effects
• tendinitis and tendon rupture in > 60 and corticosteroid use
Name 7 antibiotic inhibitors of protein synthesis with examples
• Aminoglycosides: gentamicin, neomycin, streptomycin (bactericide , prevent formation initiation complex) (g+, g-, pseudomonas)
• tetracyclines: doxycycline (bacteriostatic, block attach of charged amino acyl t rna to the A site on ribosome s.30) (mycoplasma, chlamydia, rickettsiae)
• chloramphenicol (bacteriostatic, bind to ribosome 50S to inhibit peptide transfer) (broad spec, good CSF penetration, reserved for severe haemophilus influenza bc bm suppression)
• Macrolide’s: ace azithro, clarithro, erythromycin (bacteriostatic, bind to ribosome 50s to prevent translocation) (broad spec, pseudomonas, but may aerobic G- enterobac resistant)
• lincosamides: clindamycin (bacteriostatic, ribosome 50s) ( g+ cocci, anaerobes!)
. Oxazolidinone’s: linezolid (bacterio static, 50s) (mrsa and other resistant enterococci and pneumococci)
• streptogramins: quinupristin-dalfopristin ( vancomycin resistant enterococci)
Name 2 side effects aminoglycosides
• Ototoxic
• nephrotoxic
Name 4 contraindications and side effects tetracyclines
Eg doxycycline
Contraindications,
• pregnancy
• children < 8: yellow staining developing teeth, effect bone development
Side effects
• suppress gut -flora: git upset
• resistance transmitted easily: superinfections
Which 3 antibiotics that inhibit protein synthesis share overlapping binding sites and why is this important
Macrolide’s (ace), lincosamides (clindamycin) and streptogramins (quinupristin - dalfopristin) bind to subunit 50S
Therefore if resistance to one group, resistance to all groups
Aerobic g- (esp enterobacteria) are intrinsically resistant to macrolides
Lincosamides may cause antibiotic associated pseudomenbranous colitis by removing normal anaerobic bowel flora, allowing C diff procreation
Describe the components of the chain of infection (6)
Infectious agents: bacteria prions etc →
Reservoir: people, water food →
Portal of exits: blood, secretions etc →
Mode of transmission: physical contacts, droplets, airborne (try to stop here usually)
Portal of entry: mucous membrane, broken skin etc →
Susceptible host: immune deficiency, diabetes, burns, surgery, age →.
Name 5 Tb tests
• Tb microscopy eg auramine fluorescence microscopy
• X pert mtb/rif and Xpert mtb/ rif ultra (real time pcr) (mycobacterium tuberculosis bacilli From sputum,identify rifampicin resistance, < 2 hours )
• line probe assay (genotype mtbdrplus [ ID MTB complex and detect rifampicin and isoniazid resistance ] + genotype mtbdrs/ [also detect fluoroquinolone and second line injectable drug resistances ] by HAIN life sciences)
• X pert xdr cartridge
• liquid culture (take 15 -42 days)
Name 2 limitations Gene X pert mtb/rif and Xpert mtb/ rif ultra
•Low specificity (false negatives)
• can’t determine response to treatment
Approach to Tb GXP positive and rifampicin sensitive? (2)
• Treat as tb, start on regimen 1 ripe
• send one specimen for microscopy
