Selection of Antibiotics for Empiric Therapy in Clinical Practice
Van Etta. 4-7-10- Heather Grothe
Please remember:
 the antibiotic choices listed for each diagnosis are
representative. Different hospitals and clinics may use
other agents based on the antibiograms of their
organisms or based on their purchasing group
 All choices are for empiric therapy. Antibiotic therapy
is altered based on culture results
Central Nervous System
Bacterial Meningitis - Neonate or Infants
 Clinical presentation: poor feeding, irritability, fever,
lethargy
 May not have nuchal rigidity
 BUGS- first three are three leading causes
o Strep, group B
o Enterobacteriaceae-E-coli
o Listeria
o H. influenza
o Meningococci
o Pneumococci
 Tx
o Cefotaxime (3rd gen cephalosporin) +
Ampicillin (for listeria) + dexamethasone (pt
of tx of meningitis)
o (ceftriaxone- dual secretion, through billiary
and kidney –thus not used)
Bacterial Meningitis - Adult
 Clinical presentation- headache, fever, confusion
 Nuchal rigidity
 BUGS
o Meningococci (petichiae)
o Pneumococci
o Listeria
o “Aseptic” meningitis- occurs in summer,
Enteroviruses- (and, cocksackie, polio) not
as sick
o (also H influenza if younger)
 Tx
o Ceftriaxone or cefotaxime (3rd gen cephl)good for menigoccoci
o + Vancomycin- pneumococci -19A(most are
resistant)
o + Dexamethasone
Brain Abscess

Clinical presentation- often stroke like picture with
focal neurological deficits, headache (from
hematogenous spread, contiguous spread (sinus
infection, direct implantation)
 May not be febrile!
 BUGS
o Streptococci (60-70%)
o Bacteroides (20-40%)-anaerobes
o Enterobacteriaceae (25-33%)
o Staph aureus (10-15%)-post op
o HIV (+) = toxoplasmosis
 Tx
o Ceftriaxone or cefotaxime
o + Metronidazole
o –can drain the abcess
Encephalitis- infection/inflammation of the brain (virus)
 Clinical presentation- confusion, headache, may have
fever
 Exposure history, season of year
 BUGS
o Herpes simplex
o Arboviruses (transmit by mosquito- West
Nile, St.Louis, LaCross, Equine)
o Rabies (bats, skunks, fox)
o Parasitic- neglaria (freshwater free amoeba)
 Tx
o Acyclovir (HSV)
o Others- symptomatic treatment only
Respiratory Tract
Otitis Media
 Clinical presentation- ear pain, may have fever
 Tympanic membrane-red, cloudy fluid behind
 BUGS
o Pneumococci (25-50%)
o H. influenzae (15-30%)
o B. catarrhalis (3-30%)
o Staph aureus (1%)
o Group A strep (2%)
o “Sterile” (35%, viral)
 Tx: (choose one)
o Amoxicillin- most are resistant
o Erythromycin
o Trimethoprim/Sulfamethoxazole
o Amoxicillin/Clavulanic acid
o Cefuroxime
o azithromycin
o 3rd generation oral cephalosporins
o (Cefaclor)- don’t use it! Expensive, cause
serum sickness, and not any better
o ? Observe without treating- if child in not
Imunosuppressed, or febrile, watch, big
debate
 Pharyngitis
o Clinical presentation- sore throat, may have
fever
 BUGS
o Group A, C, G strep
o “Viral”
o EBV-Fusobacterium necrophorum
BUGS- for lab proven streptococcal infection (choose
one)- thus you have to test
o Penicillin
o Erythromycin
o Clindamycin (if allergic to penicillin)
o Treat for 10 days- to prevent rheumatic
fever
Pneumonia: Community-acquired
 Clinical presentation- cough, fever, sputum
production, occ. dyspnea
 Infiltrate on CXR
 BUGS
o Pneumococci
o H. influenzae
o Mycoplasma pneumoniae
o Legionella
o Viral:
 Hanta
 influenza
 Others-metapneumovirus
 Tx: (choose one)
o Doxycycline
o Respiratory fluoroquinolone:
moxifloxacin,gatifloxacin,levofloxacin
o Ceftriaxone or Cefotaxime + azithromycin
(atypicals- legonella & mycoplasma not
covered by 3rd gen cephlosporins)
o Piperacillin / tazobactam combined with a
resp. fluoroquinolone for severe cases
o Influenza-rimantadine or oseltamivir
Pneumonia: Hospital-acquired
 Clinical presentation- cough, fever, sputum
production developing after >72 hours in the hospital
 BUGS
o Pseudomonas sp.
o Klebsiella sp.
o Enterobacter sp.
 Tx:
o Cephalosporin, 3rd generation or antipseudomonal penicillin Combined with
o Cipro or aminoglycoside (inhaled
tobramycin)
o --need to use 2 b/c of inducible beta
lactamase- prevent resistance
Cystic Fibrosis
 BUGS
o Pseudomonas aeruginosa*
o Staph aureus
o Burkholdia (Pseudomonas) cepacia
 Tx:
o Tobramycin- inhaled
o AP penicillin or ceftazidime
o Ciprofloxacin
 (always use 2 drugs)
o TMP/sulfa (for Burkholdia)

HIV / AIDS Patients




Clinical presentation
Organisms
Antimicrobial agents
BUGS
o Pneumocystis jeroveci
o (R/O (rule out) TB-tuberculosis)
 Tx:
o TMP/sulfa or
o Clindamycin + primaquine or
o Atovaquone or (mild to mod)
o Dapsone (leprosy drug)+ trimethoprim
o Always use steroids- to cut down
inflammation in the lungs
Genitourinary Tract
Cystitis- infection of the bladder
 Clinical presentation- urinary frequency, dysuria,
hematuria, urgency
 Tx:
o Enterobacteriaceae (E. coli)-85% if time
o Staph saprophyticus
o Enterococcus
 Tx: (choose one)
o TMP/SMX
o TMP
o Ciprofloxacin
o 3 day treatment course
o –no longer use amoxicillin due to resistance
Pyelonephritis- infection f the
 Clinical presentation- fever, flank or back pain,
hematuria (CVA tenderness), get UA and blood
culture
 BUGS
o Enterobacteriaceae
o Enterococci
 Tx: (choose one)
o TMP/SMX (get good blood levels!)
o Cephalosporin (3rd) or AP Pen
o Gentamicin
o Ciprofloxacin
o Treat for 2 weeks
Prostatitis
 Clinical presentation- perineal pain, low back pain,
dysuria, frequency, may have fever and chills
 Prostatic tenderness on rectal exam
 BUGS
o Enterobacteriaceae
o Pseudomonas sp.
o Chlamydia and gonoccocus in younger
patients-NAAT- nucleic acid amplified test
 Tx:
o Doxycycline + ceftriaxone or cefpodoxime
o TMP/SMX
o Ciprofloxacin
Urethritis
 Clinical presentation-dysuria, frequency
 BUGS
o Chlamydia trachomatis
o N. gonorrheae
o NAAT
o Test for syphilis
 Tx:(choose one)
o Tetracycline / Doxycycline + ceftriaxone or
cefpodoxime
o Azithromycin- will treat both pathogens, but
resistance emerging
Salpingitis (PID)
 Clinical presentation-pelvic or lower abdominal pain,
fever
 Tenderness and possible mass on pelvic examcomplication- can get abcess
 BUGS
o Gonococcus
o Chlamydia
o Bacteroides
o Enterobacteriaceae
o Streptococci
 Tx:
o Doxycycline +
o Ceftriaxone +
o Metronidazole
o or
o Cefoxitin (2nd gen ceph) + doxycycline
Gastrointestinal Tract
Cholecystitis / Cholangitis
 Clinical presentation- RUQ pain, fever, nausea
 Tenderness in RUQ on exam- use US, look for stones,
thickening of GB
 BUGS
o Enterobacteriaceae (68%)- slamonella
shigella,e coli’s , klebcellse, sreratia,
citerobacter, they all ferment glucose! (non
fermenters- pseudomonas) Cephlasporins
do not COVER ENTEROCOCCIS
o Enterococci (14%)
o Cl. perfringens (7%)-metronidazole
o Bacteroides (10%)- metro
 Tx:
o Ceftriaxone + Metronidazole
o AP Pen  Metronidazole (conver anaerobes)
Diverticulitis- inflammation of colon- RIGHT side sigmoid
colon, out pockets, due to sendentary lifestyle and high fat
diet.
 Clinical presentation-left, lower abdominal pain with
fever and diarrhea or bloody stools
 Tenderness over LLQ on abdominal exam – do a CT
for imaging
 BUGS- colon is dirty, gram everything, broad
spectrum
o Enterobacteriaceae
o Bacteroides sp.
o Enterococci
 Tx: (choose one combo)
o Gentamicin + Clindamycin
o Ceftriaxone + metronidazole
o AP Pen + Metronidazole
o Amoxacillin/clavulanate
o Ciprofloxacin + metronidazole
o TMP/SMX + metronidazole
o Tx for 7-10 days
Dysentery / Diarrhea Severe, fever, or bloody
 Clinical presentation- diarrhea, may be bloody, may
have fever
 BUGS
o Shigella sp.
o Campylobacter jejuni- #1
o Salmonella- don’t tx can put into chronic
carrier state
o E. coli 0157:H7- won’t treat!! Pushes you
into HUS!!!-hamburger
 Tx:
o Ciprofloxacin
o TMP/sulfa, erythromycin
o Do not treat E coli 0157-increases risk of
complications
Dysentery / Diarrhea Mild or moderate
 Clinical presentation – diarrhea, no fever usually, no
bloody stools
 BUGS
o Enteropathogenic E. coli
o Rotaviruses
o Norwalk agent
 Tx:
o (fluids)
o (antimotility agents)
Pseudomembranous enterocolitis
 Clinical presentation-diarrhea, may be bloody
 Tenderness on abdominal exam
 Risk of developing toxic megacolon
 May develop without antibiotic exposure, but usually
associated
 BUGS
o Clostridium difficile
 Tx:
o Metronidazole or
o Vancomycin (oral)- only time you use oral
b/c its not absorbed want in lumen
Bone and Soft Tissue Infections
Cellulitis- infection of soft tissue
 Clinical presentation- swelling, redness, painful soft
tissue area, may have fever
 BUGS
o Group A strep
o Staph aureus
 Tx:
o Clindamycin
o Nafcillin or Oxacillin
o Cefazolin / Cephalothin
o Penicillin G
Septic Arthritis - Adult
 Clinical presentation- painful, swollen, warm joint
 BUGS
o Staph aureus
o Group A strep
o Gonococci
o
o

Pneumococci
Borrelia burgdorferi (Lyme)
Tx:
o
o
o
o
o
Nafcillin or Oxacillin
or
Ceftriaxone (neg. rods) or Cefotaxime
Treat for 4 weeks
Consider Vancomycin if MRSA problem
locally
Osteomyelitis (adults)
 Clinical presentation- bone pain, may have chronic,
draining wound or sinus over the site
 Often history of trauma or previous surgery at site
 BUGS
o Staph aureus
 Tx: -choose one
o Nafcillin or Oxacillin
o Vancomycin (for MRSA concern)
o Cephalothin (1st generation)
o Clindamycin
Puncture Foot- TQ/BQ
 Pseudomonas aeruginosa (in the shoes)
 Tx:
o AP Pen or Ceftazidime +
o APAG or FQ
Bacterial Endocarditis
Bacterial Endocarditis – Acute- infection of heart valve- always
keep this in mind
 Clinical presentation- fever, night sweats, dx made
with blood cultures
 Heart murmur on exam
 BUGS
o Viridans strep (30-40%)- from mouth/teeth
o Staph aureus (20-35%)- IV drug user
o Group D strep (5-18%)
 Tx:
o Penicillin G or Ampicillin +
o Nafcillin +
o Gentamicin – put on all three
o IVDU- Staph aureus, Vancomycin (if mSRA)
Get good blood levels- doxycycline, metranidazole, TPM/sulf