Updated May 2007

Empiric Antibiotic Selection for Adults with Suspected Infections
 

This guideline is intended to assist in antibiotic selection
at the time of patient presentation with an infectious syndrome with unknown microbial etiology
.

It is not intended to guide definitive therapy.

 

Head and Neck (including CNS) Bone and Joint
Thorax Urinary tract
Abdomen/GI Obstetric-Gyn

Skin and Soft Tissue

Miscellaneous

 

Location

Syndrome

First Choice

Alternative

Comment

Head and Neck

(including CNS)

Community-Acquired Brain Abscess/Subdural empyema

 

Ceftriaxone High Dose + Metronidazole

 

 

Postoperative brain abscess/Subdural empyema

Ceftazidime + Vancomycin

Aztreonam + Ciprofloxacin + Vancomcyin (Severe beta-lactam allergy).

 

Encephalitis

Acyclovir IV

 

 

Meningitis, Community-Acquired

Ceftriaxone HD + Vancomycin

 

Add Ampicillin (or Bactrim in Pen allergic patients) if Immunocompromissed or older than 50.

 

Consider starting Dexamethasome before or at the same time of  first dose of antibiotics.

 

Consider ID consultation

Meningitis, Community-Acquired in HIV patient with CD4 below 100

Ceftriaxone High Dose + Vancomycin +  Ampicillin + Amphotericin B if opening pressure > 20 cm H2O and  AMS

Ceftriaxone High Dose + Vancomycin +  Ampicillin

Awaiting India ink report, Crypto Ag and gram-stain and culture.

Once results available, optimize therapy.

Meningitis, Postoperative

Ceftazidime + Vancomycin

Aztreonam + Ciprofloxacin + Vancomcyin (Severe beta-lactam allergy).

 

Acute otitis, NO history of Beta-lactam treatment within 30 days

Amoxicillin

Azithromcycin or Clarithromycin

 

Acute otitis media, history of Beta-lactam treatment within 30 days

Levofloxacin

Amoxicillin High Dose

 

Acute Sinusitis

See Otitis Media

See Otitis Media

Only treat if symptoms > 7 days or if pt has both facial pain and purulent discharge.

Pharyngitis

Benzathine PCN or PenVK or Amoxicillin

Erythromycin (Penicillin allergy)

 

Mild odontogenic infections

Amoxicillin

Clindamycin

 

Moderate to severe odontogenic, ENT/neck infections

Ampicillin/Sulbactam

Clindamycin + Levofloxacin

 

Thorax

Endocarditis, native valve

Vancomycin + Ceftriaxone +/- Gentamicin

 

Make sure 2-3 blood cultures are taken before starting empiric antibiotics.

Consider ID consultation

Endocarditis, prosthetic valve

Vancomycin + rifampin + gentamicin

 

Outpatient CAP, no comorbidities, no antibiotics last 3 months

Doxycycline or Azithromycin

Clarithromycin or Levofloxacin

Comorbidities: renal disease, liver disease, heart failure, immunosuppression, diabetes, malignancies, asplenia, alcoholism.

 

Avoid using Levofloxacin if TB is suspected or/and consider r/o TB.

Outpatient CAP, comorbidities, no antibiotics last 3 months

Levofloxacin

[Azithromycin or Clarithromycin] + Amoxicillin HD

Outpatient CAP, use of beta-lactam antibiotic during the last 3 months

Levofloxacin

[Azithromycin or Clarithromycin] + Amoxicillin HD

Outpatient CAP, use of quinolone antibiotic during the last 3 months

[Azithromycin or Clarithromycin] + Amoxicillin HD

Levofloxacin

Inpatient CAP, no risk factors for resistant organisms**

Ceftriaxone + Azithromycin

Levofloxacin

Inpatient CAP, no risk factors for resistant organisms**, patient admitted to the ICU

Ceftriaxone + Azithromycin

 

Use Levofloxacin and Clindamycin if patient has severe allergy to beta-lactam.

Healthcare Associated Pneumonia, no recent quinolone use

Vancomcyin + Piperacillin-tazobactam + Levofloxacin

 

Use Aztreonam instead of Piperacillin-tazobactam if severe  allergy to beta-lactam

Healthcare Associated Pneumonia, recent quinolone use, non-ICU admission, CURB-65 score < 2 and PSI score class < 4.

Vancomcyin + Piperacillin-tazobactam + Tobramycin

 

Use Aztreonam instead of Piperacillin-tazobactam if severe  allergy to beta-lactam

Healthcare Associated Pneumonia, recent quinolone use + [ICU admission or PSI score class ≥ 4 or CURB-65 score ≥ 2].

Vancomcyin + Piperacillin-tazobactam + Tobramycin + Azithromycin

 

Use Aztreonam instead of Piperacillin-tazobactam if severe  allergy to beta-lactam

Hospital Acquired Pneumonia and Ventilator Associated Pneumonia without risk factors for multi-resistant organisms***

Vancomcyin + Piperacillin-tazobactam + Levofloxacin

 

Use Aztreonam instead of Piperacillin-tazobactam if severe  allergy to beta-lactam

Hospital Acquired Pneumonia and Ventilator Associated Pneumonia with risk factors for multi-resistant organisms***

Vancomcyin + Imipenem  + Levofloxacin or Amikacin

 

Use Aztreonam instead of Imipenem if severe  allergy to beta-lactam

Pneumonia in HIV infected patient, mild or moderate, PCP very likely^^

Bactrim Pneumocystis Dose

Clindamycin + Primaquine (for allergy to sulfas)

 

or

 

Atovaquone (mainly for patients with G6PD Deficiency)

Add steroids if A-a∆ > 35 or PaO2 > 70.

Consider early bronchoscopy for etiologic diagnosis in patients with moderate severity if patient intubated or if patient not intubated and O2 sat > 90% on supplemental O2.

Pneumonia in HIV infected patient, severe (RR>30, or

intubated or FiO2 50% to keep Sat >90), and PCP very likely^^

Batrim Pneumocystis Dose, consider adding antibiotics for bacterial pneumonia

Pentamidine IV (for allergy to sulfas)

 

Consider rapid Bactrim desensitization protocol

Add steroids

Consider early bronchoscopy for etiologic diagnosis if patient intubated or if patient not intubated and O2 sat > 90% on supplemental O2.

Pneumonia in HIV infected patient, mild or moderate, and bacterial pneumonia very likely^^^

Same as CAP or HCAP

 

 

Pneumonia in HIV infected patient, severe (RR>30, or

intubated, or FiO2 50% to keep Sat >90), and bacterial pneumonia very likely^^^

Same as CAP or HCAP, consider adding PCP therapy as above

 

Consider early bronchoscopy for etiologic diagnosis if patient intubated or if patient not intubated and O2 sat > 90% on supplemental O2.

Pneumonia in HIV infected patient, mixed picture

Treat for PCP and for CAP/HCAP

 

Empyema, Comm.-Acquired

Same as CAP

 

 

Empyema, Hospital-Acquired

Same as Hospital Acquired Pneumonia

 

 

Acute exacerbations of chronic bronchitis

Amoxicillin

Doxycycline or Bactrim

 

Abdomen/GI

Community-Acquired intrabdominal infection, mild to moderate

Ceftriaxone + Metronidazole

 

or Ampicillin-sulbactam

 

or Cefoxitin.

 

Levofloxacin+ Metronidazole

 

Community-Acquired intrabdominal infection, severe, non-ICU.

Ceftriaxone + Metronidazole

 

Levofloxacin + Metronidazole

 

or

 

Ertapenem (restricted to surgical service)

 

Community-Acquired intrabdominal infection, severe, patient in the ICU

Piperacillin-tazobactam

Ceftriaxone + Metronidazole

 

Use Levofloxacin + Metronidazole if severe allergy to beta-lactams

Hospital acquired intra-abdominal infection, no risk factors for multi-resistant organisms***

Piperacillin-Tazobactam +/- Vancomycin

Aztreonam + Metronidazole +/- Vancomycin (severe Beta-lactam allergy only).

 

Hospital acquired intra-abdominal infection, risk factors for multi-resistant organisms***

Imipenem +/- Vancomycin +/- Amikacin or Levofloxacin

 

 

Acute spontaneous bacterial peritonitis (SBP)

Levofloxacin

Ceftriaxone (consider if total bilirrubin less than 2 mg/dl).

 

SBP prophylaxis in patients with acute variceal bleed

Levofloxacin

Ceftriaxone (consider if total bilirrubin less than 2 mg/dl).

 

Chronic SBP prophylalxis (for patients with ascitic fluid protein concentration of less than 15g/L)

Bactrim DS 1 tab 5 days/week

Levofloxacin q week.

 

Non-infected pancreatic necrosis

Antibiotics controversial

Antibiotics controversial

May consider imipenem only if pancreatic necrosis documented by CT and after needle aspirate has been taken from necrotic area for gram stain and culture.

Infected pancreatic necrosis

*Surgery required*

Imipenem

Ceftriaxone + Metronidazole,  or Levofloxacin + Metronidazole

 

Severe diarrhea with fever, community-acquired

Levofloxacin + Metronidazole

 

Order CDiff toxin in stool, order stool cultures, other stool studies.

Severe diarrhea with fever, hospital acquired

Consider Metronidazole

 

Order CDiff toxin in stool.

Skin and Soft Tissue

Outpatient cellulitis without abscess (including diabetic foot infections NOT associated with ulcers).

 

Cephalexin or Dicloxacillin.

Clindamycin

Add TMP-SMX or Doxycycline to above regimens if Clindamycin not selected and high suspicion of CA-MRSA.

Outpatient community acquired skin and soft tissue abscess (with or without cellulitis)

Bactrim, use MRSA dose

Doxycycline

Incision and drainage is the main therapy, and oral antibiotics may be added based on clinician judgment. If regional adenopathy rapid onset, or lymphangitic streaking use above regimens in combination with Clindamycin or a Beta-lactam (cephalexin, amoxicillin).

Inpatient community acquired cellulitis without abscess (including diabetic foot infections NOT associated with ulcers).

 

Cefazolin or Nafcillin

Clindamycin IV, or Vancomycin

Add TMP-SMX or Doxycycline to regimen if Clindamycin or Vancomycin not selected and high suspicion of CA-MRSA

Inpatient community acquired skin and soft tissue abscess (with or without cellulitis)

Vancomycin

Bactrim MRSA dose + Clindamycin IV

 

Severe community acquired soft-tissue infection (including possible necrotizing fasciitis), non-diabetic

Vancomycin + Penicillin G + Clindamycin + Gentamicin

Vancomycin + Cefazolin + Clindamycin + Gentamicin

 

Severe hospital-acquired or healthcare associated soft-tissue infection (including possible necrotizing fasciitis)

Piperacillin-Tazobactam + Vancomycin + /-Clindamycin

 

For patients with severe allergy to beta-lactams, use Aztreonam instead of Piperacillin-tazobactam.

Mild diabetic foot infection with ulcer (cellulitis/erythema extends ≤2 cm around the ulcer, and infection is limited to the skin or superficial subcutaneous tissues; no other local complications or systemic illness)

Amoxicillin/clavulanate + Bactrim MRSA dose

Clindamycin + Levofloxacin

 

Moderate diabetic foot infection (patient is systemically well and metabolically stable but has ≥1 of the following characteristics: cellulitis extending >2 cm around the ulcer, lymphangitic streaking, spread beneath the superficial fascia, deep-tissue abscess, gangrene, and involvement of muscle, tendon, joint or bone)

Ampicillin/Sulbactam  + Vancomycin

Clindamycin  + Levofloxacin

 

Severe diabetic foot infection (Infection in a patient with systemic toxicity or metabolic instability [e.g., fever, chills, tachycardia, hypotension, confusion, vomiting, leukocytosis, acidosis, severe hyperglycemia, or azotemia]).

Piperacillin-Tazobactam + Vancomycin

Clindamycin  + Levofloxacin or Ticarcillin/Clavulanate + Vancomycin

 

Human and Animal bites, outpatient

Amoxicillin/clavulanate

Levofloxacin + clindamycin, Doxycycline

 

Human and Animal bites, inpatient

Ampicillin-sulbactam

Levofloxacin + clindamycin

 

Mild surgical site infection (SSI)

Bactrim MRSA dose + Clindamycin

 

Use Clindamycin + Levofloxacin IV or Ciprofloxacin PO if sulfa allergy

Moderate SSI, no abdominal/pelvic surgery

Vancomycin + [Levofloxacin or Tobramycin]

 

 

Moderate SSI, abdominal/pelvis surgery

Vancomycin + [Levofloxacin or Tobramycin] + Metronidazole

 

 

Severe SSI (severe sepsis, septic shock, or patient in the ICU), no risk factors for multi-resistant organisms

Vancomycin + Piperacillin-tazobactam + [Levofloxacin or Tobramycin]

 

Use Aztreonam + (with Metronidazole if abdominal/pelvic surgery) instead of Piperacillin-tazobactam in patients with severe Beta-lactam allergy.

Severe SSI, abdominal/pelvic surgery (severe sepsis, septic shock, or patient in the ICU), risk factors for multi-resistant organisms

Vancomycin + Imipenem + [Levofloxacin or Tobramycin]

 

 

Bone and Joint

Septic arthritis

Vancomycin  + Ceftriaxone

Vancomycin + levofloxacin

 

Acute osteomyelitis long bones or vertebral

Vancomycin  + Ceftriaxone

Vancomycin + levofloxacin

 

Acute (or acute on chronic) osteomyelitis Contiguous to soft tissue ulcer or infection.

Same as diabetic foot infection.

 

Same as diabetic foot infection.

 

If possible delay antibiotic administration until bone cultures taken.

 

Chronic osteomyelitis

 

No empiric antibiotics recommended

No empiric antibiotics recommended

Needs surgery with bone debridement and culture

Infected prosthetic joint and infected ORIF

Vancomyin + Levofloxacin

 

Ideally obtain cultures before starting antibiotics

Urinary tract

Uncomplicated UTI (needs to meet all the following criteria: women, no functional or structural abnormality of the urinary tract).

Nitrofurantoin

Levofloxacin or Bactrim 

Avoid nitrofurantoin if CrCl<60 ml/min

Community-acquired, complicated UTI and Pyelonephritis (UTIs not meeting the uncomplicated UTI criteria)

Levofloxacin

Ceftriaxone

 

Hospital acquired or healthcare related UTI, patient not severely ill

Levofloxacin

 

 

Hospital acquired or healthcare related UTI, patient severely ill (severe sepsis, septic shock, or patient in the ICU)

Piperacillin-tazobactam +/- [Tobramycin or Levofloxacin]

 

Use Aztreonam if severe allergy to beta-lactams.

Hospital acquired or healthcare related UTI, patient severely ill (severe sepsis, septic shock, or patient in the ICU) and risk factors for multi-resistant organisms

Imipenem + [Tobramycin or Levofloxacin]

 

 

Acute Prostatitis in patients younger than 35

Ceftriaxone 250 mg IM x1 dose + Doxycycline

Ciprofloxacin PO or Levofloxacin IV

 

Acute Prostatitis in patients older than 35

Ciprofloxacin

Bactrim

 

Chronic Prostatitis

Ciprofloxacin

Bactrim

 

Asymptomatic bacteriuria in pregnant women

Nitrofurantoin

Amoxicillin/clavulanate

 

Asymptomatic bacteriuria in patients undergoing urologic procedures

Ciprofloxacin PO or Levofloxacin IV

 

 

Asymptomatic bacteriuria in other patients (including nursing home, diabetic patients)

Do not treat

Do not treat

 

Obstetric-Gyn

Mastitis, outpatient

Cephalexin + Bactrim MRSA dose.

Clindamycin + Bactrim MRSA dose.

Consider incision and drainage.

Mastitis, inpatient

Vancomycin

Bactrim MRSA dose + Clindamycin IV

Consider incision and drainage.

Postpartum Endometritis

Gentamicin + Clindamycin

Ampicillin-Sulbactam or Cefoxitin

 

Prolonged Ruptured of Membranes with fever

Ampicillin + Gentamicin

Clindamycin + Gentamicin

 

Premature rupture of Membranes without fever

Ampicillin + Erythromycin

Clindamycin + Erythromycin

 

Pelvic inflammatory disease, outpatient

Ceftriaxone 250mg IM x1 + Doxycycline +/- Metronidazole

 

 

Pelvic inflammatory disease, inpatient

Clindamycin + Gentamicin + Doxycycline

Cefoxitin + Doxycycline

Or

Ampicillin/Sulbactam + Doxycycline

 

Miscellaneous

Febrile neutropenia

Ceftazidime +/- Amikacin +/- Vancomcyin

 

or

 

Piperacillin/Tazobactam +/- Amikacin +/- Vancomcyin

Aztreonam +/- Amikacin +/- Vancomcyin (ONLY FOR SEVERE BETA-LACTAM ALLERGY)

Use Vancomycin if suspected catheter-related infection, suspected soft-tissue infection, severe mucositis, quinolone prophylaxis or history of colonization with MRSA or Penicillin-Resistant Streptococcus pneumoniae.

Community-acquired, sepsis of unknown source

Ceftriaxone +/- Vancomcyin

Vancomcyin + Levofloxacin

 

Hospital-acquired or healthcare associated, sepsis of unknown source, no risk for multi-resistant organisms

Vancomcyin + Piperacillin/Tazobactam + [Levofloxacin or Tobramycin]

Vancomcyin + Aztreonam + [Levofloxacin or Tobramycin]

(ONLY FOR SEVERE BETA-LACTAM ALLERGY)

 

Hospital-acquired or healthcare associated, sepsis of unknown source, risk for multi-resistant organisms

Vancomcyin + Imipenem + [Levofloxacin or Tobramycin]

 

 

 

** Risk factors for Resistant organisms: 1) Hospitalization for more than 4 days in the last 90 days; 2) Residence in a nursing home for more than 4 days in the last 90 days; 3) Received 3 or more days of antibiotics in the last 90 days; 4) Neutropenia (Absolute Granulocyte count less than 500 or between 500 and 1000 and decreasing). 5) Home infusion therapy, home wound care, hemodialysis in the last 30 days.

 

*** Risk factors for Multi-resistant organisms: meets one of the following criteria: 1) [ICU stay more than 3 days within last 30 days] AND/OR  [has received more than 3 days of Ceftriaxone, Ceftazidime, Levofloxacin, Ciprofloxacin, or Piperacillin/Tazobactam within the last 30 days] AND [requires pressors or has an APACHE II score less above 15]; 2)  Has received more than 3 days of Ceftriaxone, Ceftazidime, Levofloxacin, Ciprofloxacin, or Piperacillin/Tazobactam within the last 10 days.

 

^^ PCP very likely: most meet all the following criteria: 1) Not receiving or non-compliant with Bactrim prophylaxis; 2) CD4 < 200, CD4 % < 14%, or oral thrush; 3) Dyspnea of more than 7 days duration; 4) CXRay showing non-segmental infiltrates, with no pleural effusion and no adenopathy; 5) Hypoxemia or O2 desaturation with ambulation; 6) LDH > 220.

 

^^^ Bacterial pneumonia very likely: most meet all of the following criteria: 1) Fever and non-productive cough of less than 7 days duration; 2) Chest XRay showing  focal infiltrate.