Empiric Treatment of Common Infections

Empiric Antibiotic Therapy with Dr. Chmielewski

Pneumonia
Outpatient: Zithromax, Doxy-, Levaquin

Routine Inpatient: Levaquin alone, 3* Ceph + Z-max (B-lac = Ceph, PCN, Imipenem)

IC (Immunocompromised) / HA (Hosp. acquired), sick patients:
B-lac + Z-max
If vent > 7 d -> Pseudomonas, MRSA -> B-lac + Tobra + Vanco

ABx choice in HA pneumonia is hospital dependent -> depends on the local bug (check local bacterial resistance reports, e.g. in Meditech).
Use the "Hit them hard at the beginning approach".

Soft Tissue Infections
Outpatient: Cefazolin, Unasyn, Nafcillin

Routine inpatient:
DM --> GNB
If ulcer drains --> Anaerobes !
Imipenem, Ertapenem, Zosyn, Aztreonam + Clinda

B-lac allergy? --> Clinda + Z-max, Clinda + Cipro, Clinda + Aztreonam

If MRSA risk --> Vanco

PCN allergy suspected, and yet it needs Zosyn?
Skin test --> if negative--> OK
Skin test--> if positive--> Desensitize x 6 hr, PO protocol every 15 min x 6 hr - call Pharmacy dept
(ID does it on average every 2 mo for a Pt)

UTI
Check UA:
-if Nitrite+ UA --> E.coli or Klebsiella
-if Nitrite- UA --> Pseudomonas, Enterococci (Zosyn)

Outpatient: Levaquin or Cipro

Except NH patients who often already treated w Leva + E.coli resistance
(No quinolone)
NH Patients: empiric B-lac + Tobra

Always ask about previous ABx therapy.
You can use 2 GNB ABx = Aztr + Tobra
+/- Diflucan

Sepsis
No focus (no CAP, no MG, abdomen is OK, no UTI). Many times source obvious within 2 d. & it's abdomen.
PMH: ABx? How long TLC? Hospital stay?

Vanco + Zosyn + Tobra (1 dose)
No Diflucan at the beginning.
You will get Cx results back in 2 d.

Get Cortisol level. Start Hydrocortisone + Fludrocortisone

If PCN allergy --> Clinda + Levaq + Flagyl + Aztreonam?
vs. Zyvox + Aztreonam
"Hit them hard at the beginning" approach.

If patient was on Vanco (LTAC, chronic trach/vent), suspect VRE --> use Zyvox, SE: platelets drop.

Intra-abdominal Sepsis - GNB + Anaerobes
SBP - E. coli, Klebsiella, Strep --> Cefotaxime, Levaq
Enterococci less likely - no need for initial coverage

Diverticulitis - cover Enterococci !!! -> Imipenem !!!
Levaq + Flagyl , Zosyn

Below diaphragm - never use Clinda --> C.diff. risk
Always use Flagyl for anaerobes below diaphragm.

TLC, Line Sepsis
Cut 1 cm TLC tip --> Cx.
Staph. epi / Staph. aureus - Vanco +/- GNB coverage (if groin TLC or IJ TLC & sputum GNB).
ABx Tx - at least for 3 wk.

Every time MSSA/MRSA bacteremia - suspect endocarditis ! -> 2D Echo vs. TEE esp. if fever persists

Meningitis - Vanco + Ceftriax / Cefotaxime
Patient > 50 yo - Ampicillin to cover Listeria .
Aminoglycosides - not used - don't cross BBB.
Past - intrathecal injection, not anymore.

GPB - ABx CHOICE - Dr.Chmielewski

PSSA (rare, community)
MSSA--> Naf/Oxacillin, Cefazolin, Unasyn, Zosyn; Vanco, Zyvox, Synercid
MRSA--> Vanco (no B-lactams), Bactrim, Zyvox PO, Cubicin new, ID-Eli Lylli old)
VISA (slow)/VRSA (rapid, chromosome piece from VREF)

CNS (coagulase Neg.)--> like MRSA ABx
MRCNS-hosp. bug

Entercocc. fec (past-Strept.fec)--> Amp, PCN, Vanco
VREF-> Zyvox, Synercid

Strep A, B, G--> B-lactams, if PCN R--> Vanco, no tetracycl or macrolides

Pneumo-coccus (Diplo-coccus PN)--> removed from Strep group now, different bug from Strep
Diplocc-->
S--> PCN, Ceph
I--> Zyvox, Vanco, Quinilone, Macrolide, 3* Ceph.
R--> 3* Ceph + Vanco, always both in meningitis or bacteremia (just in case)

Listeria--> Amp
Corynebact--> Vanco
Bacillus antrax--> Vanco, although Cipro recommended

DDx. coverage:
Vanco = pure GPB
Aztreonam = pure GNB

GNB - ABx CHOICE - Dr.Chmielewski

Zosyn OK for almost any GNB but Acitenobacter and Legionella
Most problematic - Acetinobacter & Pseudomonas

E. coli--> no Amp., NH resident + UTI--> 30% E.coli resistant to Levaquin (Leva was already used at NH)
They come w UTI--> give Zosyn + Aminogl, 3* Cephs
DDx: effect- Genta 80% vs. Tobra 90%

E.coli - Amp. effective 30-40% only

ESBL = Extended Spectrum Beta Lactamase
E.coli, Klebsiella, Acitenobacter - inactivates most b-lactam ABx
You can use 2-3 ABx only (no Zosyn) --> Imipenem !!!

Klebsiella - always resistant to Unasyn, Zosyn OK = empiric Tx, 1* Cephs OK but not empiric Tx

Enterobacter - Zosyn, Cefepime

Proteus - Zosyn, even Unasyn OK; easy bug to treat in general

Pseudomonas - difficult to treat, even Zosyn OK only 80% !!!
Zosyn 80%, Cefepime 75% (high risk for C.diff), Imipenem 60% only, Leva 70%, Bactrim 0%
Resistant to Genta, Amikacin is better than Tobra but higher dose (3 x)
Amika 15 mg/kg
Tobra 5 mg/kg

Pseudomonas - most problematic bug (after Acitenobacter)
Zosyn effective 80% only
You have to cover w 2-3 ABx = Zosyn + Imipenem + Tobra
Within 24 hr you have S/I/R Cx & can drop 1-2 ABx

Pseudomonas pneumonia mortality > 50%

Acinetobacter- NE US Hosp
Timentin (Ticarcillin) only +/- Imipenem/Bactrim
Zosyn 0%
Worse than Pseudomonas

H.flu - Zosyn, 3* Cephs

HACEK - Zosyn, 3* Cephs, Amp + Genta (= for Endocarditis +/- Vanco)

Neisseria MG - PCN, Ceftriaxone = 3* Cephs -> if B-lactam allergy - Imipenem

References:
Practice Guidelines by Topic from the Infectious Diseases Society of America (IDSA)

Created: 2004
Updated: 2004