感染科Infectious diseases topic two: Antibiotics and bacteria

Antibiotics and bacteria

(Should consult professional advice because every doctor has his/her own perspective regarding antibiotic use.)

Author: Kendrick Johnson

1. Antibiotics and drug resistance
- mechanism: bacterial pump(1/10 of bac. genome coding for pumps); collateral damage caused by wide spectrum antibiotics and subsequent selection of resistant colonies

-  hospital monitoring:  Most bac. are sensitive to amikacin, but beware of renal toxicity); other indicators of resistance: ciprofloxacin, levofloxacin etc.

- example: E. coli resistance development(ampicillin-->cefazolin-->ceftriaxone-->carbapenem-->colistin)

2. Bacteria review

 GPC(Staphylococcus, Streptococcus, Enterococcus)

         Staphylococcus

        - coagulase (+): S. aureus

        - coagulase (-): other Staphylo

 GPB(Listeria, Bacillus, Clostridium)

 GNC(Neisseria)

 GNB(Enterobacteriaceae, NFGNB, Haemophilus)

                                           NFGNB(live on little amount of sugar)

                                           - Pseudomonas

                                           - Acinetobacter baumanii

                                           - Stenotrophomonas maltophilia 

                                              - Burkholderia

                                              - Moraxella catarrhalis

                     

3. Antibiotics categories

- Main force: cell wall inhibitors

- Assistance: protein inhibitors

- Second line: quinolone, rifampin

- Killers: Daptomycin (sounds effective but cannot kill intracellular pathogens)

4. Drug of choice( Newer drug isn't always better _)

- Syphilis, Spirochetes, Strep. group A: Penicillin G

(cp. strep group B: http://emedicine.medscape.com/article/229091-treatment)

- MSSA cellulitis: Oxacillin

- Enteroccocus: resistant to all cepha, use Penicillin G or Ampicillin

- MRSA: Vancomycin (but Vanco has poor CNS penetration)

- Infective endocarditis: Penicillin G 3-4 MU IV Q4H +Gentamicin 1mg/kg Q8H  for 4-6wks

Further reading: http://cid.oxfordjournals.org/content/49/2/320.full

-VRE: Ampicillin +Gentamicin (if sensitive), Linezolid(ZYVOX), Daptomycin
- Uncomplicated sinusitis, pharyngitis, otitis media: Amoxicillin(250-1000mg PO Q8H)
- Neonatal E. Coli infection/Adult Listeria meningitis: Ampicillin(1-3g IV Q4H-Q6H for Listeria)

- Respiratory tract infection: AUGMENTIN(Amoxicillin +Clavulanate),  UNASYN(Ampicillin +Sulbactam), sulbactam--> Acinetobacter baumannii

- Klebsiella pneumonia: Cephalosporins(3rd if community invasive infection) + aminoglycosides
- Enteric bacilli with ESBL: resistance to 3rd cephalosporins; use Imipenem or Meropenem, Ciprofloxacin
- Salmonella: Should not be treated with aminoglycosides, 1st- or 2nd- generation cephalosporins or imipenem, use 3rd cephalosporins, Quinolone, and TMP-SMZ, Ampicillin, Chloramphenicol if (S)

- Pseudomonas infection(HAP?): TAZOCIN
- Pseudomonas: aminoglycoside(UTI), Ceftazidime+aminoglycoside(pneumonia and/or bacteremia), ciprofloxacin/levofloxacin

- Stenotrophomonas infection: TMP-SMZ, TIMENTIN,  Levofloxacin 
                                                              (ticarcillin +clavulanate)
- Acinetobacter baumannii: ceftazidime, imipenem or meropenem; colistin+carbapenem or sulbactam

5. ß-Lactam antibiotics
- Penicillin, Cephem(Cephalosporin/Cephamycin), Monobactam, Carbapenem, ß-lactamase inhibitor

Penicillins
- Recite!  
                  Ampicillin + Sulbactam = Unasyn (MSSA, Acinetobacter, bacteroides)
                  Amoxicillin + Clavulanic acid = Augmentin
                  Ticarcillin + Clavulanic acid = Timentin
                  Piperacillin + Tazobactam = Tazocin
Cephems
-First-generation cephem
Cefazolin (IV)
Cephalexin (oral)

-Second-generation cephem
Cefuroxime (IV, oral)
Cefoxitin, cefmetazole (IV cephamycin)

-Third-generation cephem
Without antipseudomonal activity: Ceftazidime, Cefoperazone
With antipseudomonal activity: Cefotaxime, ceftriaxone (IV); Cefixime, cefpodoxime (oral)

-Fourth-generation cephem
Cefepime
Cefpirome

Carbapenems : for ESBL, anaerobics
- Imipenem
- Meropenem
- Ertapenem: NOT for pseudomonas, AB

Fluoroquinolones: CAN cover AB, Salmonella, Shigella, atypical, anaerobics, resistance strains, STD(gonorrhea)
- 2nd generation Ciprofloaxin (Cirpoxin): GNB, NFGNB
- 3rd generation Levofloxacin (Cravit), Moxifloxacin (Avelox)

Aminoglycosides: seldom used alone if G(+)
- Gentamycin
- Amikacin
- Recite!
                    Infective endocarditis: Penicillin G + gentamicin  
                    Enterococcus infection: Ampicillin + gentamicin
                    Staphylococcus infection: Oxacillin + gentamicin/ Vancomycin + gentamicin
Macrolides: MRSA, S. pneumonia, atypical
- Erythromycin
- Clarithromycin
- Azithromycin

SMX-TMP
- simple UTI
- PCP
- salmonella; traveler's diarrhea
- Steno/Burkholderia/Chryseo

Tetracycline (Mycoplasma, Chlamydia, Rickettsia)
-   Tetracycline: Q6H
    Minocycline: Q12H
    Doxycycline: Q24H
-   Tigercycline

Others
- Metronidazole: amoeba, Clostridium difficle
- Clindamycin: for G(+), alternative
- Chloramphenicol
- Colistin: multiple drug resistant G(-)