Micro Pharm

gsafsaf's version from 2015-06-08 23:59

Bacteria + the Cell Wall

Penicillins, Cephalosporins and Vancomycin disrupt the peptidoglycal cell wall of Gram +/- organisms. The peptidoglycan cell wall gives these organisms the ability to survive osmotic stress - this ability is lost after administration of these Abx


Question Answer
Penicillins inactivate bacterial ________transpeptidases
Penicillins prevent __________ of _________ polymerscross-linking...peptidoglycan
Due to penicillin administration, bacteria lose their cell wall ________ become susceptible to __________rigidity...rupture
Penicillins inactivate penicillin-______ proteins involved in cell wall synthesisbinding
Major cause of resistancebacterial production of ß-lactamases (enzymatic degradation of the drug)
Major cause of resistance in MRSAmediated by alterations in the penicillin-binding protein structures (most often PBP 2, which is used by both penicillins and cephalosporins
Capable of producing penicillinaseS. aureus
Capable of producing penicillinaseE. coli
Capable of producing penicillinaseP. aeruginosa
Capable of producing penicillinaseN. gonorrhoeae
Capable of producing penicillinaseBacillus
Capable of producing penicillinaseProteus
Capable of producing penicillinaseBacteroides
Penicillin G (prototype)Pneumococci
Penicillin G (prototype)Streptococci
Penicillin G (prototype)Staphylococci (non-penicillinase producing)
Penicillin G (prototype)Bacillus
Penicillin G (prototype)Gonococci (non-penicillinase producing)
Benzanthine Penicillin G (IM)Treponema pallidum
Penicillin G (prototype)Leptospira
Penicillin VOral form, poor bioavailability
ProbenicidUricosuric agent (used in gout) that blocks renal secretion of penicillin, rarely used for this purpose
Penicillinase-resistant penicillinsOxacillin, Dicloxacillin, Methicillin, Nafcillin (all oral administration); mostly used for Staph. infxns, but decreased use bc of MRSA
Extended-spectrum penicillins Ampicillin, Amoxacillin, Piperacillin; Inactivated by ß-lactamases; broadened gram negative coverage
AmpicillinH. influenzae
AmpicillinStrep. pneumo
AmpicillinStrep. pyogenes
AmpicillinN. meningitidis
AmpicillinProteus mirabilis
AmpicillinEnterococcus faecalis
AmoxicillinBetter oral absorption
AmoxicillinEndocarditis prophylaxis
Clavulanic acidNo antimicrobial properties; irreversibly inhibits ß-lactamase; given alongside Amoxicillin
Sulbactamß-lactamase inhibitor; given alongside Ampicillin
Piperacillin+tazobactamPseudomonas spp., Bacteriodes
Clindamycin/azithromycinGiven as endocarditis prophylaxis to those allergic to penicillins
Asplenic patientsshould get penicillin prophylaxis for encapsulated organisms such as Strep. pneumo + H. Influenzae


Penicillins are distributed thru out body fluids; they penetrate the CSF


Question Answer
Substitutions at R1 determineantibacterial acitivity
Substitutions at R2 determinePharmacokinetics
Probenecid Uricosuric agent (used in gout) that slows renal secretion of cephalosporins
Each newer generation of cephalosporins is increasinglyresistant to prenicillinases
3rd Generationsensitive to another class of ß-lactamase - the cephalosporinases
Cephalexin, Cefazolin, Cefadroxil1st Generation
1st GenerationE. coli, Klebsiella, prophylaxis for some surgical procedures
Cefoxitin, Cefaclor, Cefuroxime, Cefotetan, Cefprozil2nd Generation
2nd GenerationStreptococcus, Proteus, most anaerobes, E. Coli, Klebsiella
2nd GenerationUTI, Respiratory + soft-tissue infxns
Cefdinir, Cefixime, Cefotaxime, Ceftizoxime, Ceftazidime, Ceftriaxone3rd Generation
3rd GenerationEnhanced gram-negative activity
3rd GenerationH. influenzae, Neisseria spp., Enterobacter, Salmonella, Proteus, Seratia, E. coli; gram negative hospital acquired infxns
Most 3rd GenerationsPenetrate CSF
Ceftriaxone3rd Generation, STD gonorrhea, empiric therapy for community-acquired meningitis
Ceftriaxone + CefoparazoneExcreted by biliary tract (can use for biliary tree infxns), while most 3rd generations have renal excretion
Ceftriaxone + CefamendoleDisulfiram-like alcohol intolerance
Prevent cephalosporin induced bleeding disorders wVit. K administration
Cefepime + Ceftaroline4th Generation
CefepimePseudomonas spp.
Cephalosporins may be nephrotoxic when administered wdiuretics
Cephalosporins are the number one cause of hospital-acquiredC. diff colitis

Antimicrobial prophylaxis

Question Answer
High risk for endocarditis and undergoing surgical or dental proceduresAmoxicillin, cephalexin, penicillin
Exposure to gonorrheaCeftriaxone
History of recurrent UTIsTMP-SMX, amoxacillin, cephalexin, nitrofurantoin
Exposure to meningococcal infectionCeftriaxone, ciprofloxacin, or rifampin
Pregnant woman carrying group B strepAmpicillin, Penicillin G
Prevention of gonococcal conjunctivitis in newbornErythromycin ointment
Prevention of post surgical infection due to S. aureusCefazolin
Prophylaxis of strep pharyngitis in child w prior rheumatic feverBenzathine penicillin G or oral penicillin V
Exposure to syphilisBenzathine penicillin G

Infection control techniques

Question Answer
AutoclavePressurized steam at >120C
AutoclaveMay be sporicidal
AlcoholsDenature proteins and disrupts cell membranes
AlcoholsNOT sporicidal
ChlorhexidineDenatures proteins and disrupts cell membranes
ChlorhexidineNOT sporicidal
Hydrogen peroxideFree radical oxidation
Hydrogen peroxideSporicidal
Iodine and iodophorsHalogenaion of DNA, RNA, and proteins
Iodine and iodophorsMay be sporicidal

Abx/Antivirals/Antifungals to avoid in pregnancy

Question Answer
FluoroquinolonesCartilage damage
TetracyclinesDiscolored teeth, inhibition of bone growth
ChloramphenicolGray baby syndrome

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