Infectious Diseases Flashcards
What are the risks of using medications for a resistant organism on a sensitive organism?
High treatment failure rate.
Particularly with vancomycin use for sensitive staphylococci in the blood.
First agents in sensitive Staphylococcal isolates
IV: Oxacillin, Nafcillin, Cefazolin (1st gen.)
Oral: Dicloxacillin, Cephalexin, Cefadroxil (1st gen.)
Additional agents in sensitive Staphylococcal isolates
IV: any cephalosporin, any carbapenem, beta-lactam/beta lactamasae combinations
Oral: Amoxicillin/Clavulanate, any oral cephalosporin
MRSA Drugs
Dalbavancin Oritavancin Telavancin Tedizolid Linezolid Vancomycin Daptomycin
First agents in resistant Staphylococcal isolates
IV: Vancomycin, Linezolid, Daptomycin, Ceftaroline, Oritavancin, Telavancin, Dalbavancin
Oral: Linezolid, TMP/SMX, Doxycycline
Additional agents in resistant Staphylococcal isolates
IV: Oritavancin, Dalbavancin, Telavancin
Oral: Tedizolid
What is the best empiric therapy for gram positive cocci growing from blood cultures?
Vancomycin (to cover resistance until sensitivity testing results are available)
If intolerant or allergic to Vancomycin, use Linezolid, Daptomycin or Ceftaroline.
Adverse effects of MRSA drugs
Linezolid, Daptomycin, Tigecycline
Linezolid - Thrombocytopenia, interaction with MAO inhibitors
Daptomycin - CPK elevation; not effective in the lung
Tigecycline - Not used for MRSA in the blood
Treatment for minor MRSA infections of the skin
TMP/SMX
Clindamycin
Doxycycline
Linezolid
Penicillin G, VK, Benzathine treats
Viridans group streptococci, Streptococcus pyogenes, Oral anaerobes, Syphilis, Leptospira
Ampicillin and Amoxicillin treats
E.coli, Lyme disease, other gram negative bacilli and same organisms covered with Penicillin.
What is the most accurate diagnostic test for infectious diseases
Culture
Amoxicillin is the best initial therapy for …?
Otitis media
Dental infections
Endocarditis prophylaxis
Lyme disease limited to rash, joint or 7th CN involvement
UTI in pregnant woman (or nitrofurantoin)
Listeria monocytogenes
Enterococcal infections
What are the penicillinase resistant penicillins (PRP’s)
Oxacillin
Cloxacilin
Dicloxacillin
Nafcillin
PRP’s are used to treat:
Skin infections: Cellulitis, Impetigo, Erysipelas.
Endocarditis, meningitis and bacteria from staphylococci
Osteomyelitis and septic arthritis with proven sensitive organism.
Not active against MRSA or Enterococcus
Piperacillin, Ticarcillin, Azlocillin, Mezlocillin cover which organisms?
Gram negative bacilli (E.coli, Proteus)
Pseudomonads
Cephalosporins, Piperacillin, Ticarcillin, and Mezlocillin are the best initial therapy for?
Nearly always used in combination with a beta-lactamase inhibitor such as Tazobactam or Clavulanic acid
Cholecystitis and ascending cholangitis Pyelonephritis Bacteremia Hospital acquired and ventilator associated pneumonia Neutropenia and fever
If these are caused by single organisms such as streptococci or anaerobes, treat using a narrower agent
All cephalosporins treat …?
Group A, B and C streptococci Viridans group streptococci E. coli Klebsiella Proteus mirabilis
How are ESBL producing MDRO’s treated?
- ESBL = Extended spectrum beta-lactamase producing organisms
- MDRO’s = Multi drug resistant organisms
Carbapenems
An ESBL resistant to Carbapenem is treated with:
- Ceftolozane/Tazobactam
- Ceftazidime/Avibactam
- Polymyxin
What organisms are resistant to all forms of Cephalosporins?
MRSA
Listeria (Tx: Amoxi)
Enterococcus (Tx: Amoxi)
Delafloxacin (fluoroquinolone) is used to treat …?
MRSA of skin/soft tissue
Gram negative rods
Only quinolone that does not prolong QT interval
First Generation Cephalosporins (Cefazolin, Cephalexin, Cephradine, Cefadroxil) are usted to treat …?
Staphylococci (MSSA)
Streptococci (except Enterococcus)
Gram negative bacilli like E.coli, not Pseudomonas
Osteomyelitis, septic arthritis, endocarditis, cellulitis
Second Generation Cephalosporins (Cefotetan, Cefoxitin, Cefaclor, Cefprozil, Cefuroxime, Loracarbef) can cover … ?
Same organisms as 1st gen cephalosporins
Add coverage for anaerobes and more gram negative bacilli.
What is the best initial therapy for PID?
Cefotetan or Cefoxitin (2nd gen.) combined with doxycycline.
Cefotetan and Cefoxitin increase the risk of bleeding and give a disulfiramlike reaction with alcohol.
Cefuroxime, Loracarbet, Cefproxil, and Cefaclor (2nd gen.) are usted to treat?
Respiratory infections: Bronchitis, Otitis media and Sinusitis.
Ceftriaxone (3rd gen.) is used to treat?
First line for pneumococcus, including partially insensitive organisms:
- Meningitis
- Community acquired pneumonia (combined with macrolides)
- Gonorrhea
- Lyme involving heart or brain
Why is Ceftriaxone (3rd gen.) avoided in neonates?
Impaired biliary metabolism
Cefotaxime (3rd gen.) is used to treat?
Spontaneous bacterial peritonitis (SBP)
Cefepime (4th gen.) is used to treat?
Neutropenia and fever
Ventilator associated pneumonia
Better Staphylococcal coverage compared with 3rd gen.
Ceftaroline (5th gen.) is used to treat?
Gram negative bacilli
MRSA
NOT Pseudomonas
Which Cephalosporin has pseudomonal coverage?
Ceftazidime (3rd gen.)
Which are the only Cephalosporins that cover anaerobes?
Cefotetan and Cefoxitin (2nd gen.)
Both deplete prothrombin and increase risk of bleeding
Carbapenems (Imipenem, Meropenem, Ertapenem, Doripenem) cover and treat?
Gram negative bacilli (including Pseudomonas) Resistant Anaerobes Streptococci Staphylococci
Treat neutropenia and fever
How is Ertapenem different to other Carbapenems?
Does not cover Pseudomonas
What is Aztreonam used for?
Exclusively for gram negative bacilli including Pseudomonas.
NO cross reaction with penicillin
Fluoroquinolones (Ciprofloxacin, Gemifloxacin, Levofloxacin, Moxifloxacin) can be used to treat?
- Ventilator associated pneumonia (VAP), Community acquired pneumonia (CAP), including penicillin resistant pneumococcus (except Cipro)
- Gram negative bacilli including most pseudomonas
- Cystitis, pyelonephritis
- Diverticulitis and GI infections
Ciprofloxacin is mostly used to treat for?
Cystitis
Pyelonephritis
Ventilator associated pneumonia (VAP)
How are diverticulitis and GI infections treated?
Ciprofloxacin, Gemifloxacin and Levofloxacin combined with Metronidazole (to cover anaerobes)
Moxifloxacin as single agent for diverticulitis
What are some side effects of Quinolones?
- Bone growth abnormalities in children and pregnant women.
- Tendonitis and Achilles tendon rupture.
Aminoglycosides (Gentamycin, Tobramycin, Amikamicin) are mostly used to treat?
Gram negative bacilli (bowel, urine, bacteremia)
Synergistic with beta lactic abx for enterococci and staphylococci
What are negative effects of Aminoglycosides?
Nephrotoxic
Ototoxic
No effect on anaerobes (need O2 to work)
Doxycycline treats?
Bronchitis
Lyme disease limited to rash, joint, or 7th CN palsy
Rickettsia
MRSA of skin and soft tissue (cellulitis)
Primary and secondary syphilis (allergic to penicillin)
Borrelia, Ehrlichia and Mycoplasma
Chlamydia
What adverse effects are associated to Doxycycline use?
Tooth discoloration (children)
Fanconi syndrome (Type II RTA proximal)
Photosensitivity
Esophagitis/Ulcers
Trimethoprim/Sulfamethoxazole (TMP/SMX) is used to treat?
Cystitis
Pneumocystis pneumonia treatment and prophylaxis
MRSA of skin and soft tissue (cellulitis)
What side effects can TMP/SMX have?
Rash
Hemolysis in G6PD deficiency
Bone marrow suppression (folate antagonist)
Beta-lactam/Beta-Lactamase Combinations are used to treat?
Anaerobes
First choice for mouth and GI abscess
How are anaerobes treated?
Oral (above diaphragm)
- Penicillin (G, VK, ampicillin, amoxicillin))
- Clindamycin
Abdominal/Gastrointestinal:
- Metronidazole
- Beta-lactam/lactamase combinations
- Carbapenems
Others:
- Piperacillin
- Cephalosporin (2nd gen.)
What infections are caused by Gram Negative Bacilli (E.coli, Klebsiella, Proteus, Pseudomonas, Enterobacter, Citrobacter)?
- Bowel (Peritonitis, Diverticulitis)
- Urinary Tract (Pyelonephritis)
- Liver (Cholecystitis, Cholangitis)
What agents cover Gram Negative Bacilli?
Quinolones Aminoglycosides Carbapenems Piperacillin, Ticarcillin Aztreonam Cephalosporin Polymyxin (last resource due to nephrotoxicity)
