id quick Flashcards
If you see gram positive cocci in clusters, think…
Staphylococcus (MSSA, MRSA)
If you see gram positive cocci in pairs and short chains, think…
Streptococci, enterococci
If you see gram positive bacilli, think…
Listeria, Corynebacterium, Clostridium
If you see gram negative bacilli, think…
Enterobacteriacea (E. coli, Klebsiella, Enterobacter)
Pseudomonas, Stenotrophomonas
If you see gram negative coccobacilli, think…
H. influenzae, Pasturella, Brucella
If you see gram negative diplococci, think…
Neisseria, Moraxella, Acinetobacter
What flora are normally found on human skin?
Staphylococcus aureus (MSSA, MRSA) Streptococcus pyogenes (Group A streptococcus) Staphylococcus epidermidis (CNST)
What flora are normally found in human nasopharynx?
Streptococcus pneumoniae
Hemophilus influenzae
Moraxella catarrhalis
Streptococcus pyogenes
What flora are normally found in human oropharynx?
Peptococcus Peptostreptococcus Streptococci (viridans) Fusobacterium Eikenella
What flora are normally found in distal human GI tract?
Escherichia coli Several species in each of these classes: • Klebsiella • Proteus • Enterococcus • Bacterioides
What flora are normally found in human urinary tract?
Escherichia coli
Klebsiella
Enterococcus species
What species are commonly resistant to penicillin based on their production of beta-lactamases?
E. coli, Klebsiella spp, H. influenzae & M. cattarhalis
Note: if just beta lactamase, carbapenems still work
What does spp mean wrt Abx?
several species
Which organisms most commonly produce carbapenemases?
Pseudomonas, E.coli, Klebsiella, and Acinetobacter spp.
What are the members of the beta lactam family?
Penicillins, cephalosporins, and carbapenems
How do beta lactam Abx work? (MOA, properties)
Cell wall-active agents
Bactericidal
Time-dependent killing
Name some penicillins
- penicillin V & penicillin G
- ampicillin (IV) & amoxicillin
- amoxicillin – clavulanic acid
- cloxacillin
- piperacillin - tazobactam
So note: piptazo and amoxclav are still penicillins, they just have an add-on beta-lactamase-inhibitor, which counteracts the main mechanism of bacterial resistance
What is Pen G/V useful against?
Narrow spectrum agent; mostly aerobic gram positive cocci
Beta-hemolytic strep (group A, B, C, G) Tremponema pallidum (Syphillis)
Also: n. meningitidis, though some resistance
oral anaerobes
enterococcus
What is Pen G/V NOT useful against?
most gram negative organisms
beta-lactamase producing organisms (S. aureus - ~90%)
What are amoxicillin/ampicillin useful against?
narrow spectrum agent; mostly Gram positive aerobes, some Gram
negative aerobes
Everything Penicillin does plus: HiPEEL:
- H. influenzae (~25% resistance)
- Proteus mirabilis
- E. coli (~30% resistance)
- enterococcus (E.faecalis vs. penicillin)
- Listeria monocytogenes (HiPEEL)
What is Amox-Clav useful for?
Amoxicillin + ß-lactamase inhibitor
– broad-spectrum agent
– extends spectrum of amoxicillin to cover more gram negatives (E.coli, H. influenzae, Salmonella, Shigella) + gut anaerobes (B. fragilis)
Note: does NOT cover pseudomonas
What is Pip-Tazo useful for?
Most broad-spectrum penicillin; aerobic Gram positives (including MSSA, E. faecalis), difficult aerobic Gram negatives (including Enterobacter, Klebsiella, Serratia, Pseudomonas, Acinetobacter), anaerobes (including B. fragilis)
What is cloxacillin useful for?
Drug of choice for MSSA; otherwise pretty narrow spectrum, not widely used
What is important to know about the cephalosporins re MOA and gram +/- activity?
beta lactams
generally, earlier gen better gram + worse gram - and later gen worse gram + better gram -
Name 1st gen cephalosporins
cefazolin
cephalexin
cefadroxil
What are 1st gen cephalosporins useful for?
Narrow spectrum:
– aerobic gram positives (MSSA, ß-hemolytic Streptococcus)
– Some aerobic gram negatives (PEcK: Proteus, E.coli,
Klebsiella)
– oral anaerobes
NOT for enterococci, gut anaerobes
Name 2nd gen cephalosporins
cefuroxime, cefaclor, cefprozil, cefoxitin
What are 2nd gen cephalosporins useful for?
Oral stepdown therapy for CAP!
“Middle of the road” coverage
• Covers [almost] everything that 1st generations cover:
– Gram positives: MSSA, Streptoccocus (↓activity vs. 1st generation)
– Gram negatives: PEcK + H. influenzae & Moraxella
– oral anaerobes, NOT gut anaerobes
*exception: cefoxitin – poor Gram positive coverage; covers B. fragilis (but
resistance ~20%)
Name 3rd gen cephalosporins
ceftriaxone, cefotaxime, ceftazidime
What are 3rd gen cephalosporins useful for?
ceftriaxone and cefotaxime:
Broad-spectrum
• Gram positive coverage: MSSA (reasonable coverage), Streptococcus (excellent coverage)
• Gram negatives: difficult to kill Gram negatives (Serratia, Enterobacter, Citrobacter), N.menigitidis, N.gonnorhea (ceftriaxone)
• oral anaerobes
NOT: enterococcus, pseudomonas, gut anaerobes
What is ceftazidime useful for?
Pseudomonas!
documented Pseudomonal infections and empiric Gram negative coverage where Pseudomonal coverage is desired
What is ceftriaxone useful for?
N. menigitidis, N. gonorrhea
Name 4th gen cephalosporins
cefepime (trick Q, there’s only 1 of them!)
What are 4th gen cephalosporins useful for?
treatment of documented Pseudomonal infections, empiric Gram negative
coverage where Pseudomonal coverage is desired
broad-spectrum
• Like ceftriaxone, but:
– Gram positives: better activity vs. MSSA
– Gram negatives: Pseudomonas
Remember, it’s JUST cefepime
What are the carbapenems?
- Ertapenem
- Meropenem
- Imipenem-cilastin
- Doripenem
Generally, what are carbapenems useful for?
“Tanks” of the ß-lactams • Extremely broad-spectrum: - most aerobic Gram positives - most aerobic Gram negatives- including ESBLs!!! - most anaerobes - Drugs of choice for ESBLs
Reserve for serious infections with resistant organisms!
What are ESBLs?
Extended Spectrum Beta Lactamase bacteria produce an enzyme that can break down commonly used antibiotics
Name the fluroquinolones
– ciprofloxacin
– levofloxacin
– moxifloxacin
How do the fluoroquinolones work?
MOA: inhibit DNA gyrase – inhibit DNA replication
Bactericidal
Concentration-dependent killing
What is ciprofloxacin useful for?
aerobic gram negatives (Pseudomonas if susceptible; increasing resistance)
NOT useful for: gram positive or anaerobic infections
What are levofloxacin and moxifloxacin useful for?
aerobic gram positives/Gram negatives, atypicals
Classic indication: CAP
eg atypicals: Chlamydia, Mycoplasma, Legionella
NOT useful for: MRSA, enterococcus
Note: some differences, eg pseudomonas levo is better, gut anaerobes moxi is better
Name the aminoglycosides
– tobramycin
– gentamicin
– amikacin
How do aminoglycosides work?
Antimicrobial Properties – bactericidal – concentration-dependent killing Mechanism of Action: – inhibit 30S ribosomal unit – inhibit protein synthesis
What are aminoglycosides useful for?
- Narrow spectrum; aerobic gram negatives only (including ESBLs)
- Can be used for synergy with a ß-lactam against Gram positives (streptococci, enterococci)
Useful for: aerobic gram negatives, ESBLs, Pseudomonas (tobramycin)
Not useful for: gram positives (except synergy with ß-lactams)
• Differences between agents:
– Klebsiella, Serratia: G > T > A
– Pseudomonas: T > G >A
– Amikacin has lowest resistance; but 4X higher MICs
Name the macrolides
– erythromycin
– azithromycin
– clarithromycin
How do macrolides work?
Antimicrobial Properties – bacteriostatic – time-dependent killing Mechanism of Action: – inhibit 50S ribosomal unit – inhibit protein synthesis
What are macrolides good for?
Relatively broad-spectrum
– Gram positives: Streptococci (note increasing resistance with S. pneumoniae ~20%)
– some Gram negatives (A & C only): H. influenzae, M. cattarhalis
– atypicals
– NO anaerobic coverage
Useful for: Niche: RTIs, Legionella
Not useful for: MRSA, enterococcus
What is the PEcK mnemonic for?
First gen cephalosporins
PEcK = Proteus, Escherichia coli, Klebsiella
What is the most common pathogen in acute rhinitis?
Viral (rhinovirus, coronavirus, influenza, RSV, parainfluenza, adenovirus)
What is the Abx for acute rhinitis?
None – viral
What is the most common pathogen in pharyngitis?
Viral (rhinovirus, coronavirus, influenza, parainfluenza, adenovirus, coxsackievirus)
What is the most common pathogen for strep pharyngitis?
Group A beta-hemolytic streptococcus
What is first-line for treating strep pharyngitis?
Children and adults: penicillin
Erythromycin 2nd line for both
What are the most common pathogens for sinusitis?
S. pneumoniae
H. influenzae
M. catarrhalis
S. aureus
What is first-line for treating sinusitis?
Children and adults: amox
2nd line for both: amox-clav
What organisms cause Acute Otitis Media?
S. pneumoniae H. influenzae M. catarrhalis Group A Strep S. aureus
Rx for acute OM
if treating:
amox, then amox-clav (both adult and ped)
Otitis externa: organisms
P. aeruginosa
Coliforms
S. aureus
Otitis externa: Rx
Cortisporin® otic solution 4 drops tid or qid (3 drops tid or qid for children) TM defect: Ciprodex® otic suspension 4 drops bid x 5 d
Necrotizing (i.e. bone involvement): ciprofloxacin 750 mg PO bid x 4-8 wk
Bronchitis: organisms
viral
Bronchitis: Tx
None – viral
Pneumonia: CAP, no comorbidity: organisms
S. pneumoniae
M. pneumoniae
C. pneumoniae
Pneumonia: CAP, no comorbidity: Rx
First line: Amoxicillin erythromycin clarithromycin azithromycin
Pneumonia: CAP, with comorbidity: organisms
S. pneumoniae
M. pneumoniae
C. pneumoniae
H. influenzae
Pneumonia: CAP, no comorbidity: Rx
amox, amox/clav, cefuroxime, cefprozil
PLUS clarithromycin, azithromycin, doxycycline
OR levofloxacin, moxifloxacin [unclear if these are solo or adjunct to line 1]
Dental infections: Rx
penicillin or clindamycin
Diarrhea: organisms?
Enterotoxigenic E. coli (ETEC) Campylobacter
Salmonella
Shigella
Viruses Protozoa
Diarrhea: Rx?
symptomatic if mild
If mod-severe: fluoroquinolones (olfloxacin, norfloxacin, ciprofloxacin, levofloxacin)
If kids: Azithromycin – safe, tolerable, easily administered
If coming from south/southeast Asia, may have quinolon-resisitant campylobacter: use azithromycin
Diarrhea post-Abx: organisms?
C difficile
Diarrhea post-Abx: Rx?
mild-moderate: metronidazole
Severe (WBC≥15, Cr ≥1.5x baselin): vancomycin
Peptic ulcer disease (non-NSAID): organism?
H pylori
Peptic ulcer disease (non-NSAID): Rx?
First line:
PPI + amox + clarithromycin
Or
PPI + metronidazole + clarithromycin
Vulvovaginal candidiasis: Rx?
fluconazole orally
miconazole intravaginal
Other -azole tx available OTC
Bacterial vaginosis: organisms?
Overgrowth of:
G. vaginalis
M. hominis
Anaerobes
Bacterial vaginosis: Rx?
first line: metronizadole PO; metronidazole or clindamycin intravaginally
In which patients would you treat asymptomatic BV?
high-risk pregnancy, prior IUD insertion, gynecologic surgery, induced abortion, or upper tract instrumentation
HSV: Rx?
First and recurrent episodes: acyclovir, famiciclovir, valacyclovir
Can do prophylaxis in pregnancy starting at 36w
Gonorrhea/Chlamydia: Rx?
ceftriaxone 250 mg IM x 1 dose + azithromycin 1 g PO single dose
or
doxycycline 100 mg PO bid x 7 d
Mastitis: organisms?
S. aureus
S. pyogenes
Mastitis: Rx?
cloxacillin
cephalexin
Tinea Cruris/Pedis (jock itch/athlete’s foot): organism?
clotrimazole
ketoconazole
Cellulitis (uncomplicated): organisms?
S. aureus
Group A Streptococcus
Cellulitis (uncomplicated): Rx?
1st line: cephalexin
2nd line: cloxacillin or clindamycin
Note: Tx for 10-14d
If ?penicillin allergy: can you use cephalosporins?
If rash: cephalosporins OK
If anaphylaxis do NOT use cephalosporins
MRSA
Vancomycin, Linezolid, Daptomycin
Pseudomonas
Pip-Tazo, Carbapenems, Cefepime
Outpt Pneumonia
Doxycycline, Azithromycin, Moxifloxacin
Inpt Pneumonia
CAP: 3rd gen cephalosporin + Azithromycin
HAP: Vancomycin + Pip-Tazo
Neutropenic fever
Cefepime (4th gen cephalosporin)
Carbapenems
UTI
Trimethoprim-sulfamethoxazole, Nitrofurantoin
Meningits
Vancomycin, Ceftriaxone, +/- steroids, +/- Ampicillin
Cellulitis
Cefazolin, Trimethoprim-sulfamethoxazole, clindamycin
IV Vancomycin
Anaerobe: what’s your strategy?
Gut or vagina: metronidazole
Everywhere else: clindamycin
Staph: what’s your strategy?
Methicillin (eg cloxacillin)
MRSA: Vancomycin
Vancomycin-resistant: Linezolid
Gram negatives: what’s your strategy?
start with Amoxicillin (with or without clav); don’t cover pseudomonas
If Pseudomonas coverage needed, bump up to Piperacillin-Tazosin
Brand names: ancef is …
cefazolin
Brand names: flagyl is …
metronidazole
Brand names: Bactrim, Septra is …
sulfamethoxazole-trimethoprim
