| Infection |
Most Common Causative Organism(s) |
Empiric Antibiotic Choices |
| Periorbital Cellulitis |
- Staphylococcus aureus (MSSA and MRSA)
- Group A streptococcus
|
Periorbital Cellulitis Antibiotic Recommendations |
| Orbital Cellulitis |
- S. aureus (MSSA and MRSA)
- Group A streptococcus
- Anginosus group streptococci (S. anginosus, constellatus, and intermedius)
- S. pneumoniae
- Haemophilus influenzae
- Anaerobes
|
Orbital Cellulitis Antibiotic Recommendations |
| Lymphadenitis |
- Acute bacterial lymphadenitis:
- S. aureus (including MSSA and MRSA)
- Group A streptococcus
- Oral anaerobes, if concern for poor dentition/odontogenic source
- Note: bilateral disease is most often due to viral infections (e.g., Epstein-Barr virus)
- Rare causes generally associated with subacute presentations:
- Bartonella henselae
- Nontuberculous mycobacteria
|
- Acute bacterial lymphadenitis:
- Cephalexin
- or
- Amoxicillin/clavulanate
- or
- Clindamycin if history of MRSA or MRSA risk factors
(e.g., family with MRSA) or allergy to first-line β-lactam – assess need for alternative
- Antibiotic treatment is not generally recommended for immunocompetent hosts with lymphadenitis caused by B. henselae because it does not reduce duration of illness
- Discuss with ID and refer to general surgery clinic if concern for nontuberculous mycobacteria
|
| Peritonsillar Abscess |
- Group A streptococcus
- Oral anaerobes (Fusobacteria, Prevotella, Veillonella species)
- S. aureus (including MSSA and MRSA)
|
Peritonsillar Abscess Antibiotic Recommendations |
| Retropharyngeal Abscess |
- S. aureus (including MSSA and MRSA)
- Group A streptococcus
- Respiratory anaerobes
- S. anginosis group
|
Neck Space Infection Antibiotic Recommendations |
| Dental Abscess |
Oral anaerobes (e.g., Fusobacteria, Prevotella, Veillonella species) |
Dental Abscess Antibiotic Recommendations |
| Pharyngitis, Exudative |
- Most pharyngitis is caused by viral infections (e.g., Epstein-Barr virus, adenovirus)
- Bacterial etiologies:
- Group A streptococcus
- If sexually active:
|
Pharyngitis Antibiotic Recommendations |
| Acute Bacterial Sinusitis |
- S. pneumoniae
- H. influenzae
- M. catarrhalis
|
- Amoxicillin or amoxicillin/clavulanate
- Penicillin allergy:
- Cefdinir or cefpodoxime (preferred) or
levofloxacin (alternative)
|
| Otitis Media without Perforation |
- S. pneumoniae
- H. influenzae
- M. catarrhalis
|
Acute Otitis Media Pathway Antibiotic Recommendations |
| Mastoiditis |
- Acute mastoiditis:
- S. pneumoniae
- Group A streptococcus
- S. aureus (including MSSA and MRSA)
- H. influenzae
- Pseudomonas aeruginosa (rare)
- Additional considerations for chronic mastoiditis:
- Pseudomonas aeruginosa
- Upper respiratory anaerobes
|
- Acute mastoiditis:
- Chronic mastoiditis:
|
| Cellulitis, Non-purulent |
Group A streptococcus |
Cellulitis/Abscess Pathway Antibiotic Recommendations |
| Purulent Cellulitis/Abscess |
- S. aureus (including MSSA and MRSA)
- Group A streptococcus
|
| Pyomyositis |
- S. aureus (including MSSA and MRSA)
- Group A streptococcus (rare)
- E. coli, K. pneumoniae (very rare)
|
- Non-severe:
- No MRSA risk factors: cefazolin
- Personal or family history of MRSA, IV drug use: clindamycin (if known history of clindamycin-resistant MRSA, select antibiotic based on prior susceptibilities)
- Severe, rapidly progressing, ill:
- Contact ID to discuss empiric antibiotics
- Vancomycin + ceftriaxone (see also Sepsis Pathway)
|
| Necrotizing Fasciitis |
- Group A streptococcus
- S. aureus (including MSSA and MRSA)
- Clostridium spp (e.g., perfringens, septicum)
- Aeromonas hydrophila
- Vibrio spp
- K. pneumoniae, E. coli (rare)
|
- Emergent surgical debridement
- Contact ID to discuss empiric antibiotics, which may vary depending on clinical scenario
- Vancomycin + piperacillin-tazobactam + clindamycin
|
| Septic Arthritis |
- S. aureus (including MSSA and MRSA)
- Group A streptococcus
- Kingella kingae
- Borrelia burgdorferi
- Rare causes of septic arthritis:
- Neisseria gonorrhoeae (sexually active individuals)
- Salmonella (children and adolescents with sickle cell disease)
|
|
| Osteomyelitis |
- S. aureus (including MSSA and MRSA)
- Group A streptococcus
- Kingella kingae
- Rare causes of osteomyelitis:
-
- S. pneumoniae
- Salmonella in (children and adolescents with sickle cell disease)
|
Osteomyelitis Pathway Antibiotic Recommendations |
| Community-acquired Pneumonia |
- Viral infections are the most common cause of community-acquired pneumonia
- Bacterial etiologies:
- S. pneumoniae
- H. influenzae
- S. aureus (including MSSA and MRSA)
- Group A streptococcus
|
|
| Urinary Tract Infection (Cystitis, Pyelonephritis) |
- Enterobacterales (e.g., E. coli, K. pneumoniae)
- P. aeruginosa (child with underlying genitourinary disease)
- Enterococcus spp.
|
|
| Meningitis/Encephalitis |
- Infants/children > 56 days
- Bacterial disease:
- S. pneumoniae
- N. meningitidis
- H. Influenzae
- Other etiologies:
- Herpes simplex (HSV)
- Enterovirus (summer months)
- Borrelia burgdorferi
- Tuberculosis (rare)
|
Recommended Empiric Antibiotics for Acute Bacterial Meningitis |
| Ventriculitis/ Ventricular Shunt Infection |
- Coagulase-negative Staphylococcus spp
- S. aureus (including MSSA and MRSA)
- Enterobacterales (E. coli, Klebsiella spp, Enterobacter spp)
- P. aeruginosa
- Cutibacterium (Propionibacterium) acnes
|
Recommended Empiric Antibiotics for Suspected VP Shunt Infections |
| Intraabdominal Infection (excluding pelvic inflammatory disease) |
- Enterobacterales (e.g., E. coli, K. pneumoniae)
- Lower intestinal anaerobes (e.g., Bacteroides fragilis)
- Enterococcus spp.
- P. aeruginosa (rare)
- Streptococcus pneumoniae (spontaneous bacterial peritonitis)
|
- Antibiotic choice depends on the type of intra-abdominal infection and comorbid medical conditions; the following serves as a general guide:
- Appendicitis Pathway
- Non-appendicitis intraabdominal infection:
- Community onset/non-severe
- Hospital onset/immunocompromised/severe:
- Consider infectious disease consultation
|