Septic Arthritis Nursing Guide

Septic Arthritis Overview

Septic arthritis (infectious arthritis) is a joint space infection — a medical and surgical emergency. Untreated, articular cartilage is destroyed within 24–48 hours by bacterial enzymes and the host inflammatory response.

Emergency: Any hot, swollen, painful, non-weight-bearing joint with fever is septic arthritis until proven otherwise. Time to joint washout within 24 hours — every hour of delay → cartilage loss.

Causative Organisms by Population

Population	Organism	Notes
Adults (most common)	Staphylococcus aureus	~50% of all cases; MRSA increasingly common in healthcare-associated
Sexually active young adults	Neisseria gonorrhoeae	Disseminated gonococcal infection — multiple joints, skin lesions, tenosynovitis
IV drug users, immunocompromised	MRSA, Pseudomonas, Candida	Consider unusual organisms
Children <5 years	Streptococcus, H. influenzae, S. aureus	Hip joint most common — emergency
Elderly, diabetic	S. aureus, Gram-negatives	Knee most common; presentation may be atypical
Prosthetic joint	S. epidermidis, S. aureus, late: P. acnes	Divided: early (<3 months), delayed (3–12 months), late (>12 months)

Risk Factors

Existing joint disease (rheumatoid arthritis, OA, crystal arthropathy)
Prosthetic joint
Diabetes mellitus, immunosuppression (steroids, biologics, HIV)
IV drug use
Recent intra-articular injection or arthroscopy
Skin infections or penetrating trauma adjacent to joint
Haematogenous spread from distant infection (UTI, skin infection, dental)
Sickle cell disease (salmonella, S. aureus)

Diagnosis

Clinical Presentation

Feature	Details
Joint swelling	Rapid onset effusion; tense, warm joint
Pain	Severe, constant; worsened by any movement including passive
Fever	Present in ~60–70%; absence does not exclude
Reduced range of motion	Patient holds joint in position of maximum comfort (knee flexed 15–20°)
Non-weight-bearing	Classic sign — patient refuses to bear weight on affected limb
Systemic sepsis features	Tachycardia, hypotension, rigors in severe cases

Most common joints: Knee (50%), hip (20%), ankle, wrist, shoulder

Joint Aspiration (Arthrocentesis) — Gold Standard

Nurse's role: Preparation, consent support, positioning, specimen labelling and immediate dispatch to lab. Fluid must be sent IMMEDIATELY — cells deteriorate rapidly.

Synovial Fluid Analysis	Normal	Septic Arthritis	Crystal Arthropathy
Appearance	Clear yellow	Turbid, purulent	Yellow, slightly turbid
WBC (cells/μL)	<200	>50,000 (often >100,000)	2,000–50,000
PMN %	<25%	>90%	50–90%
Glucose	Normal (blood glucose)	Low (<50% serum)	Normal
Gram stain	Negative	Positive in 60–80%	Negative
Culture	Negative	Positive in 80–90%	Negative

WBC >50,000/μL in joint fluid = septic arthritis until proven otherwise. Do not wait for culture — start antibiotics immediately after aspiration.

Blood Investigations

FBC: Leucocytosis (raised WBC) — neutrophilia
CRP/ESR: Markedly elevated; CRP >150 mg/L strongly suggests septic arthritis
Blood cultures: BEFORE antibiotics — positive in 50% of septic arthritis
Uric acid: Normal in septic arthritis (elevated in gout) — but gout and septic arthritis CAN coexist
Imaging: X-ray (soft tissue swelling, baseline bone); ultrasound (effusion, guided aspiration); MRI gold standard for adjacent osteomyelitis

Treatment

Empirical Antibiotic Protocol

Patient Group	Empirical Antibiotic	Duration
Adults, no MRSA risk, no penicillin allergy	Flucloxacillin 2 g IV every 6 hrs	4–6 weeks total (IV → oral switch)
MRSA risk (hospital-acquired, dialysis, prosthetic)	Vancomycin IV (trough 15–20 mcg/mL)	4–6 weeks
Gonococcal arthritis	Ceftriaxone 1 g IV daily for 7–14 days	14 days; test and treat partner
Gram-negative / immunocompromised	Piperacillin-tazobactam 4.5 g IV TDS	4–6 weeks
Prosthetic joint	Vancomycin + rifampicin (after MDT)	Orthopaedic MDT decision

Narrow antibiotic based on culture results when available. IV to oral switch at 2 weeks if good response.

Joint Washout

Surgical washout: Arthroscopic lavage or open arthrotomy — gold standard for hip joint (anatomy limits needle aspiration) and most cases
Serial aspiration: May be acceptable in peripheral joints (knee, wrist) if rapid improvement and WBC falling
Hip joint: ALWAYS requires surgical drainage — proximity to femoral head blood supply; avascular necrosis risk if delayed
Decision: orthopaedic surgeon within hours of diagnosis

Nursing Care Plan

Pain Management

Regular analgesia: paracetamol 1 g QDS + NSAIDs (caution: renal function, GI bleeding) + opioids for severe pain
Splint or rest affected joint in position of function — reduces pain and maintains joint alignment
Passive range-of-motion exercises once infection controlled (guided by physiotherapist)
Pain scores (NRS or VAS) documented every 4 hours

Monitoring and Safety

Vital signs: 4-hourly temperature, HR, BP, RR — monitor for systemic sepsis
CRP/ESR/WBC: Monitor trend every 48–72 hrs — falling values confirm response
Joint inspection: Daily — document warmth, swelling, skin colour, ROM
IV antibiotic administration: Vancomycin requires pre-infusion trough levels; Red Man Syndrome if infused too fast — dilute in 250 mL and infuse over 60 min
DVT prevention: Immobilised limb — TED stockings, LMWH as per assessment
Skin integrity: Splinted limbs at risk of pressure injury — check bony prominences

Patient Education

Importance of completing full antibiotic course
Physiotherapy engagement for joint rehabilitation
Signs of recurrence or deterioration — return to ED if fever, increasing pain
STI partner notification if gonococcal arthritis confirmed
Prosthetic joint patients: antibiotic prophylaxis before dental/invasive procedures

GCC-Specific Context

Septic Arthritis in the GCC

Brucella arthritis: Endemic zoonosis in GCC — particularly Saudi Arabia, Kuwait, Oman. Raw camel milk, raw goat/sheep products consumption. Brucella causes chronic arthritis (sacroiliac, hip, knee). Test: Brucella serology (Rose Bengal titre, SAT) and blood cultures on BACTEC at 4 weeks. Treatment: doxycycline + rifampicin ± gentamicin × 6 weeks
Salmonella arthritis: In sickle cell patients — Salmonella species cause septic arthritis; treat with ciprofloxacin or ceftriaxone
MRSA prevalence: Healthcare-associated MRSA rates higher in GCC tertiary centres — empirical vancomycin for hospital-acquired septic arthritis
Intra-articular corticosteroid injections: Common practice in GCC private clinics for OA/RA — risk of introducing infection; sterile technique essential. Post-injection septic arthritis presentations seen in polyclinic settings
Diabetes and immunosuppression: High GCC diabetes prevalence increases risk of atypical, delayed and severe septic arthritis presentations

Exam Tips

Synovial WBC >50,000 with PMN >90% = septic arthritis
Most common organism: S. aureus
Young sexually active adult: Neisseria gonorrhoeae
Hip joint = always surgical drainage (arthrotomy)
Brucella arthritis — classic GCC/Middle East question
Send synovial fluid IMMEDIATELY to lab — cells deteriorate
Blood cultures BEFORE antibiotics

Exam MCQs — DHA / SCFHS / QCHP

Q1. A 45-year-old male with Type 2 diabetes presents with a hot, swollen right knee, fever 38.9°C and refuses to bear weight. Synovial fluid aspirate shows 85,000 WBCs/μL with 95% PMNs. What is the diagnosis and IMMEDIATE priority?

A) Gout flare — start colchicine and NSAIDs B) Septic arthritis — start IV antibiotics immediately after sending cultures and refer to orthopaedics for washout C) Reactive arthritis — NSAIDs only; self-resolving D) Rheumatoid arthritis flare — administer IV methylprednisolone

✅ B — WBC >50,000 with >90% PMNs = septic arthritis. Start IV antibiotics immediately (after blood cultures and synovial culture sent). Urgent orthopaedic referral for joint washout. DO NOT give steroids — will worsen infection. Gout can coexist but must treat septic arthritis first.

Q2. A nurse is administering vancomycin 1 g IV for septic arthritis. The patient develops generalised flushing, erythema across the neck and chest, and hypotension during the infusion. What is the MOST LIKELY cause and action?

A) Anaphylaxis — stop infusion, administer adrenaline 0.5 mg IM B) Red Man Syndrome — slow or stop infusion; administer antihistamine; NOT an allergic reaction C) Systemic sepsis worsening — increase oxygen and call the medical team D) Expected side effect — continue infusion at same rate

✅ B — Red Man Syndrome is a rate-related (non-immune) reaction to vancomycin caused by direct mast cell degranulation from rapid infusion. Treatment: slow or stop infusion, diphenhydramine (antihistamine). Prevent by infusing vancomycin over at least 60 minutes in 250+ mL. NOT a true allergy — patient can receive vancomycin again with pre-medication and slower rate.

Q3. A patient in Saudi Arabia has chronic low back pain and hip arthritis with positive Brucella serology titre 1:320. What is the MOST APPROPRIATE antibiotic regimen?

A) Amoxicillin 500 mg TDS × 7 days B) Doxycycline + rifampicin for 6 weeks C) Flucloxacillin IV for 4 weeks D) Single-dose ceftriaxone IM

✅ B — Brucella arthritis requires prolonged dual antibiotic therapy: doxycycline 100 mg BD + rifampicin 600–900 mg OD for minimum 6 weeks. Single antibiotics lead to high relapse rates. Brucellosis is endemic in the GCC and a classic exam topic for Saudi Arabia, Kuwait and Oman nursing exams.

Q4. A child presents with fever, refusal to walk and left hip pain. The hip is held in flexion, abduction and external rotation. What is the PRIORITY nursing action?

A) Administer NSAIDs for pain and reassess in the morning B) Arrange immediate orthopaedic referral — septic arthritis of hip is a surgical emergency requiring urgent washout C) Arrange elective orthopaedic outpatient appointment within 2 weeks D) Apply traction to the hip and reassess after 24 hours of rest

✅ B — Septic arthritis of the hip in a child is an orthopaedic emergency. The hip's blood supply (lateral epiphyseal vessels) is at risk from elevated joint pressure — delay causes avascular necrosis of the femoral head and permanent disability. Requires emergency surgical drainage, IV antibiotics and inpatient management. Never delay.

🦴 Septic Arthritis