Infectious%20arthritis Treatment

Principles of Antibiotic Therapy

• Appropriate antibiotic treatment should be started once specimens for microbiology studies are submitted
• Broad-spectrum antibiotics are recommended while culture results are pending because of the serious and destructive nature of the infection
• Antibiotics should be given by the parenteral route initially
• Antibiotic therapy should be revised once results of culture and antimicrobial susceptibility are available

Factors Affecting Choice of Antibiotics for Empiric Therapy

• Age of patient
• Clinical history, physical examination findings, risk factors
• Results of synovial fluid Gram stain
• Ability of the antibiotic to penetrate joint
• Likely pathogens causing infectious arthritis and their local antimicrobial susceptibility patterns (see below)

Antibiotics for Empiric Parenteral Therapy

Adults: Based on results of synovial fluid Gram stain

Gram Stain Result	Recommended Empiric Antibiotics
Gram-positive cocci, community-acquired infection or without risk for Methicillin-resistant Staphylococcus aureus (MRSA)	Vancomycin or β-lactam agent (Cefazolin, Nafcillin, Oxacillin, Flucloxacillin) if without allergies to penicillins
Gram-positive cocci, hospital-acquired or with other risk for MRSA	Vancomycin or Clindamycin*
Gram-negative bacilli	3rd generation cephalosporin (Ceftazidime, Ceftriaxone, Cefotaxime) with or without Aminoglycoside
Gram-negative cocci	Ceftriaxone

*If patient’s isolate turns out to be susceptible to Clindamycin but resistant to Erythromycin, a D test should be done to check for the presence of inducible Macrolide-Lincosamide-Streptogramin B resistance

Adults: Based on patient’s clinical profile

• Recommendations below may be used to guide antibiotic choice if Gram stain is negative

Clinical Profile	Recommended Empiric Antibiotics
No risk factors for atypical organisms	Flucloxacillin
Immunocompetent	Vancomycin
Immunocompromised patients, injection drug users, traumatic bacterial arthritis	Vancomycin with 3rd generation cephalosporin or an aminoglycoside
Risk factors for MRSA infection (eg catheters, recent hospital confinement)	Vancomycin* plus 2nd or 3rd generation cephalosporin
N gonorrhoeae infection suspected	Ceftriaxone plus Azithromycin or Doxycycline

* If patient has allergy or drug intolerance to Vancomycin, Daptomycin, Linezolid, Clindamycin or Co-trimoxazole are reasonable alternatives

Children: Based on age

Age of Child	Probable Pathogen	Recommended Empiric Antibiotics
Neonate	S aureus, Group B streptococci, Gram-negative bacilli	Antistaphylococcal penicillin (Nafcillin*, Vancomycin or Clindamycin)** plus 3rd generation cephalosporin plus Aminoglycoside
≤ 5 years	S aureus, S pneumoniae, S pyogenes, H influenzae, K kingae	Antistaphylococcal penicillin (Nafcillin*, Vancomycin or Clindamycin)** plus 2nd or 3rd generation cephalosporin
		Extended-spectrum penicillin with or without β-lactamase inhibitor
>5 years	S aureus, S pyogenes, S pneumoniae, Group A streptococci	Antistaphylococcal penicillin (Nafcillin*, Vancomycin or Clindamycin)**
Adolescent, sexually active	N gonorrhoeae	3rd generation cephalosporin (Ceftriaxone, Cefotaxime)

*Nafcillin may be used if <10% of community-acquired S aureus isolates are Methicillin-resistant
**Vancomycin or Clindamycin may be used for empiric treatment if >10% of community-acquired S aureus isolates are Methicillin-resistant

Duration of Treatment

• Parenteral antibiotics are usually given for 2 weeks followed by oral antibiotics for 2 to 4 weeks
• Duration of antibiotic therapy depends on the site of infection, presence of adjacent osteomyelitis, etiologic agent, clinical and laboratory response
  • Arthritis from S aureus and Gram-negative organisms may require longer treatment durations compared to arthritis from S pneumoniae, S pyogenes and H influenzae, P aeruginosa, Enterobacter spp
  • 7-10 days of antibiotic treatment is required for gonococcal arthritis
  • Infectious arthritis of the hip and spine may require a longer period of antibiotic therapy

Oral Antibiotic Therapy

• Treatment for infectious arthritis may be continued using oral antibiotics once infection and inflammation are adequately controlled
• An oral antibiotic with appropriate antimicrobial coverage should be chosen
• Adherence to oral antibiotic regimen should be ensured as well as careful patient monitoring
• Oral antibiotics often used in infectious arthritis treatment include Cloxacillin, Dicloxacillin, Cefalexin, Clindamycin, Quinolones
• Oral regimen should have the same coverage as the intravenous (IV)/intramuscular (IM) drug that produced improvement of symptoms