Septic arthritis resident survival guide

Septic arthritis Resident Survival Guide
Overview
Causes
FIRE
Diagnosis
Treatment
Do's
Don'ts

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Iqra Qamar M.D.[2], Aditya Ganti M.B.B.S. [3]

Overview

Causes

Gram-negative bacilli account for 10 to 20% of septic arthritis causes. ~10% of patients with nongonococcal septic arthritis are due to polymicrobial cause of infections. Anaerobes are also can cause septic arthritis in few cases. Most common cause of septic arthritis in children age < 2 years are Haemophilus influenzae (in immunized children), Staph. aureus, group A Streptococcal infections and Kingella kingae. The source of infection in most of the cases (~50%) often from the skin, lungs or bladder.

Common Causes

Common microorganisms causing septic arthritis includes:

• Staphylococcus aureus
• Streptococcal pyogenous
• Streptococcal agalectae
• Streptococcal pneumonia
• Neisseria gonorrhoeae
• Escherichia coli
• Staphylococcus epidermidis
• Haemophilus influenzae
• Pseudomonas aeruginosa
• Salmonella

Less Common Causes

• Peptostreptococcus
• Bacteroides fragilis
• Fusobacterium species 
• Borrelia burgdorferi
• Brucella
• Mycobacterium tuberculosis
• Mycoplasma hominis
• Fungal infection such as
  • Blastomycosis
  • Cryptococcus
  • Coccidioidomycosis
  • Sporotrichosis
  • Candida

FIRE

Diagnosis

Complete diagnostic approach:

Common Presentation Symptoms in newborns or infants: Cries when infected joint is moved (e.g. diaper change causes crying if hip joint is infected) Fever Inability to move the limb with the infected joint (pseudoparalysis) Irritability Symptoms in children and adults: Inability to move the limb with the infected joint (pseudoparalysis) Intense joint pain Joint swelling Joint redness Low fever The tenosynovitis is characterized by pain, swelling, and erythema around the tendon Less common Presentation Chills
Focused History Intravenous drug use Sexual activity Terminal complement deficiency Dog or cat bite Ingestion of unpasteurized dairy products Nail through shoe Soil exposure/gardening Soil or dust exposure containing decomposed wood (north-central and southern United States) Southwestern United States, Central and South America (primary respiratory illness) Cleaning fish tank
Physical Examination Appearance of the Patient Patient with septic arthritis usually appears toxic and with joint pain children usually appear irritable Vital Signs Low grade fever. Chills and spiking fever are very rare. Hyperthermia over the joint involved Tachycardia Tachypnea Skin Warmth over the joint Erythema over the around the joint that involved Disseminated gonococcal infection often present with skin lesions, typically multiple, painless macules and papules, most often found on the arms or legs or on the trunk. Extremities Most commonly involves knee > hip > shoulder > ankle. Other joints such as sacroiliac joint (~10%), sternoclavicular or costoclavicular joints may be involved in patient with history of intravenous drug abuse (IVDA), penetrating trauma, animal or human bites and local steroid injections. Swelling of the joint that involved Decreased range of motion such as pseudo paralysis Patient hold the hip in flexed and externally rotated position if SA involving hip. If child, unwillingness to bear weight on the affected joint (antalgic gait)
Laboratory Workup CBC with DC SMA-7 Creatine kinase Urinalysis with microscopic examination Erythrocyte sedimentation rate C-reactive protein Synovial fluid analysis Synovial WBC count with differential Crystal analysis Gram stain Culture and sensitivity
Imaging Study Plain radiographs of swollen joints Swelling of the joint capsule and soft tissue around the joint Fat pad displacement Joint space widening due to localized edema and effusion. Computed tomography (CT) Visualization of joint effusion Soft tissue swelling Para-articular abscesses Joint space widening due to localized edema, bone erosions, foci of osteitis, and scleroses. Magnetic resonance imaging (MRI) Synovial enhancement Perisynovial edema Joint effusion Signal abnormalities in the bone marrow
Other Investigation PCR Arthrocentesis In the presence of joint effusion to differentiate between different causes of arthritis

Synovial Fluid Analysis

Synovial fluid analysis include:

• Synovial WBC count with differential
• Crystal analysis
• Gram stain
• Culture and sensitivity

Normal synovial fluid appears as clear, transparent, thick in viscosity with WBC count less than 200 mm3 and < 25% of PMN, where as in septic arthritis and other arthritis synovial fluid analysis will be as follows:

Type of Arthritis	Color	Transparency	Viscosity	WBC count (per mm3)	PMN cellcount (%)	Gram stain	Gram Culture	polymerase chain reaction (PCR) test	Crystals
Normal	Clear	Transparent	High/thick	< 200	< 25	Negative	Negative	Negative	Negative
Gonococcal arthritis	Yellow	Cloudy-opaque	Low	34,000 to 68,000	> 75	Variable (< 50 percent)	Positive (25 to 70 percent)	Positive (> 75 percent)	Negative
Non-gonococcal arthritis	Yellowish-green	Opaque	Very low	> 50,000 (> 100,000 is more specific)	> 75	Positive (60 to 80 percent)	Positive (> 90 percent)	--	Negative
Inflammatory: crystalline arthritis (e.g.Gout, Pseudogout)	Yellow	Cloudy	Low/thin	2,000 to 100,000	> 50	Negative	Negative	Negative	Positive
Inflammatory: non-crystalline arthritis (e.g. Rheumatoid arthritis, reactive arthritis)	Yellow	Cloudy	Low/thin	2,000 to 100,000	> 50	Negative	Negative	Negative	Negative
Noninflammatory arthritis (e.g. Osteoarthritis)	Straw	Translucent	High/thick	200 to 2,000	< 25	Negative	Negative	Negative	Negative
Lyme's arthritis	Yellow	Cloudy	Low	3,000 to 100,000 (mean: 25,000)	> 50	Negative	Negative	Positive (85 percent)	Negative

Treatment

Empiric treatment should be commenced as soon as possible after culture samples have been obtained. The choice of empiric antibiotics should be determined on the basis of: Gram stain results of synovial fluid analysis Local prevalence of organisms and resistance patterns Predisposing factors including intravenous drug use, hospitalization, or colonization of infectious pathogens, and risk for methicillin-resistant Staphylococcus aureus (MRSA) If the patient fails to respond to initial treatment, consider: Misidentification of causative pathogen Infection with atypical pathogen Concurrent osteomyelitis Occult nidus of infection Intra-articular antibiotics are not useful as it may increase infection rate and also causes chemical synovitis and cartilage toxicity. Methicillin-resistant Staphylococcus aureus (MRSA) Patient at high risk of methicillin-resistant Staphylococcus aureus (MRSA) include: Known MRSA colonization or infection Recent hospitalization Nursing-home resident Presence of leg ulcers Indwelling catheters

Antimicrobial Regimen – Empiric Therapy:

Newborn (< 1 week)	Newborn (1–4 weeks)	Infants (1–3 months)	Children (3 months–14 years)	Adults
High Risk for MRSA Preferred Regimen Vancomycin 18 mg/kg/day IV q12h AND Cefotaxime 50 mg/kg IV q12h Low Risk for MRSA Cefotaxime 50 mg/kg IV q12h AND Nafcillin 25 mg/kg IV q8h or Oxacillin 25 mg/kg IV q8h	High Risk for MRSA Preferred Regimen Vancomycin 22 mg/kg/day IV q12h AND Cefotaxime 50 mg/kg IV q8h Alternative Regimen Clindamycin 5 mg/kg IV q8h Low Risk for MRSA Preferred Regimen Cefotaxime 50 mg/kg IV q8h AND Nafcillin 37 mg/kg IV q6h OR Oxacillin 37 mg/kg IV q6h Alternative Regimen Clindamycin 5 mg/kg IV q6h	High Risk for MRSA Preferred Regimen Vancomycin 40 mg/kg/day IV q6–8h AND Cefotaxime 50 mg/kg IV q8h Low Risk for MRSA Preferred Regimen Cefotaxime 50 mg/kg IV q8h AND Nafcillin 37 mg/kg IV q6h OR Oxacillin 37 mg/kg IV q6h Alternative Regimen Clindamycin 7.5 mg/kg IV q6h	Preferred Regimen Vancomycin 40 mg/kg/day IV q6–8h AND Cefotaxime 50 mg/kg IV q8h	Monoarticular At risk for sexually-transmitted disease Preferred Regimen Ceftriaxone 1 g IV q24h OR Cefotaxime 1 g IV q8h OR Ceftizoxime 1 g IV q8h Alternative Regimen Vancomycin 1 g IV q12h Not at risk for sexually-transmitted disease Preferred Regimen Vancomycin 1 g IV q12h AND Ceftriaxone 1 g IV q24h OR Cefotaxime 1 g IV q8h OR Ceftizoxime 1 g IV q8h Alternative Regimen Vancomycin 1 g IV q12h AND Ciprofloxacin 400 mg IV q12h OR Levofloxacin 750 mg IV q 24 h Polyarticular Preferred Regimen Ceftriaxone 1 g IV q24h

Antimicrobial Regimen – Synovial Fluid Gram Stain-Based Therapy:

Gram stain result	First choice antibiotic	Second choice antibiotic
Negative Gram stain	Vancomycin 15–20 mg/kg q8–12h and Ceftazidime 2 g IV q8h or Cefepime 2 g IV q8–12h	Daptomycin 6-8 mg/kg IV q24h or Linezolid 600 mg IV/PO q12h and Piperacillin-Tazobactam 4.5 g IV q6h or Aztreonam 2 g IV q8h or Imipenem 500 mg IV q6h or Meropenem 1 g IV q8h or Doripenem 500 mg IV q8h or Carbapenems
Gram-positive cocci	Vancomycin 15–20 mg/kg q8–12h	Daptomycin 6-8 mg/kg IV q24h or Linezolid 600 mg IV/PO q12h
Gram-negative cocci	Ceftriaxone 1 g IV q24h or Cefotaxime 1 g IV q8h
Gram-negative bacilli	Ceftazidime 2 g IV q8h or Cefepime 2 g IV q8–12h or Piperacillin-Tazobactam 4.5 g IV q6h	Aztreonam 2 g IV q8h or Imipenem 500 mg IV q6h or Meropenem 1 g IV q8h or Doripenem 500 mg IV q8h or

Antimicrobial Regimen – Pathogen Based Therapy:

Microorgnaism		First choice antibiotic	Second choice antibiotic
Staphylococcus aureus	Methicillin-sensitive	Nafcillin 2 g IV QID or Clindamycin 900 mg IV TID	Cefazolin 0.25–1 g IV/IM q6–8h, Vancomycin 500 mg IV q6h or 1 g IV q12h
	Methicillin-resistant	Vancomycin 15–20 mg/kg IV q8–12h in adults or 15 mg/kg IV q6h in children or Linezolid 600 mg PO/IV q12h in adults or 10 mg/kg PO/IV q8h in children	Sulfamethoxazole-trimethoprim 3.5–4.0 mg/kg PO/IV q8–12h in adults or Minocycline ± rifampin
Coagulase-negative Staphylococcus spp	Methicillin-sensitive	Nafcillin 2 g IV QID or Clindamycin 900 mg IV/IM TID	Cefazolin 0.25–1 g IV/IM q6–8h vancomycin 500 mg IV q6h or 1 g IV BD
	Methicillin-resistant	Vancomycin 1 g BD or Linezolid 600 mg BD	Sulfamethoxazole-trimethoprim or Minocycline ± rifampin or Clindamycin
Group A streptococcus, Strep. pyogenes		Penicillin G 2 million IV/IM every 4 h or Ampicillin 2 g IV QID	Clindamycin 600–1200 mg/day IV/IM q6–12h Cefazolin 0.25–1 g IV/IM q6–8h
Group B streptococcus, Strep. agalactiae		Penicillin G 2 million IV/IM every 4 h or Ampicillin 2 g IV every 6 h	Clindamycin 600–1200 mg/day IV/IM q6–12h Cefazolin 0.25–1 g IV/IM q6–8h
Enterococcus spp.		Ampicillin 2 g IV QID or Vancomycin 1 g IV BD	Ampicillin-sulbactam 3 g IV QID Linezolid 600 mg PO/IV BD
Escherichia coli		Ampicillin-sulbactam 3 g IV QID	Cefazolin 0.25–1 g IV/IM q6–8h, levofloxacin 500–750 mg IV/PO OD Gentamicin 3–5 mg/kg/day IV q6–8h Sulfamethoxazole-trimethoprim 8–10 mg/kg/day IV/PO q6–12h
Proteus mirabilis		Ampicillin 2 g IV QID or Levofloxacin 500 mg IV/PO OD	Cefazolin 0.25–1 g IV/IM q6–8h Sulfamethoxazole-trimethoprim 8–10 mg/kg/day IV/PO q6–12h Gentamicin 3–5 mg/kg/day IV q6–8h
Proteus vulgaris, Proteus rettgeri, Morganella morganii		Cefotaxime 2 g IV QID Imipenem 500 mg IV QID, or Levofloxacin 500 mg IV/PO OD	Gentamicin 3–5 mg/kg/day IV q6–8h, or Ticarcillin-clavulanate 3.1 g IV q4–6h
Serratia marcescens		Cefotaxime 2 g IV QID	Levofloxacin 500 mg IV/PO OD Gentamicin 3–5 mg/kg/day IV q6–8h Imipenem 500 mg IV QID
Pseudomonas aeruginosa		Cefepime 2 gm IV BD or Piperacillin 3 gm IV QID or Imipenem 500 IV QID	Ticarcillin-clavulanate 3.1 g IV q4–6h Tobramycin 3-5 mg/kg/day IV q6–8h Amikacin 15 mg/kg/day IV/IM q8–12h Ciprofloxacin 400 mg IV q8–12h
Neisseria gonorrhea		Ceftriaxone 2 g IV OD or Cefotaxime 1 g TID	Levofloxacin 500 mg IV/PO OD Ampicillin 2 g IV QID
Bacteroides fragilis group		Clindamycin 900 mg IV/IM TID or Metronidazole 500 mg TID	Ampicillin-sulbactam 3 g IV QID or Ticarcillin-clavulanic acid 3.1 g IV QID
Brucella melitensis		Doxycycline 100 mg PO BD and Streptomycin 15 mg/kg IM QID or Rifampin 600–900 mg QID	Doxycycline 100 mg PO BD and Gentamicin 5 mg/kg IV QID
Haemophilus influenzae		Amoxicillin-Clavulanate 875/125 mg PO BD or Cefprozil 500 mg PO BD or Cefuroxime 500 mg PO BD or Cefdinir 600 mg PO OD	Levofloxacin 750 mg IV/PO OD or Moxifloxacin 400 mg IV/PO OD or Clarithromycin 500 mg PO BD
Morganella morganii		Cefotaxime 2 g IV QID or Imipenem 500 mg IV QID or Levofloxacin 500 mg IV/PO OD	Gentamicin 3–5 mg/kg/day IV q6–8h or Ticarcillin-Clavulanate 3.1 g IV q4–6h
Tropheryma whipplei		Penicillin G 2 million units IV q4h for 2 weeks and Streptomycin 1 g IM/IV OD for 2 weeks, then TMP-SMX 160mg/800mg PO OD for 1 year	Ceftriaxone 2 g IV OD, then TMP-SMX 160mg/800mg PO OD for 1 year
Borrelia burgdorferi		Amoxicillin 500 mg TID for 28 days or Doxycycline 100 mg BD for 28 days or Cefuroxime 500 mg BD for 28 days	Azithromycin 500 mg PO OD for 7–10 days or Clarithromycin 500 mg PO BD for 14–21 days or Erythromycin 500 mg PO QID for 14–21 days

Duration of Antimicrobial Therapy:

Clinical Setting	Duration
Staphylococcus aureus infection	3–4 weeks
Streptococcus groups A, B, C, G infection	3–4 weeks
Gram-negative bacilli infection	4 weeks
Brucella infection	6 weeks
Borrelia burgdorferi infection	30 days
Mycobacterium tuberculosis infection	9 months
Candida albicans infection	6 weeks
Prosthetic joint infection	6 weeks
Post-intraarticular injection or post-arthroscopy	14 days

Do's

Don'ts

References