Prosthetic joint, heart valve and cardiac device infections

At a glance

• Implanted material lets bacteria form biofilm: organisms in a matrix that resist antibiotics and the immune system. Cure usually needs surgery as well as antibiotics.
• Timing after implantation predicts the organism and whether the implant can be saved.
• Get microbiology before antibiotics in a stable patient: aspirate the joint, take several blood cultures, sample tissue at surgery.
• Joints: DAIR for early infection with a stable implant; one- or two-stage exchange otherwise. Treat for 12 weeks after DAIR (DATIPO).
• Cardiac devices: every confirmed infection, including an isolated pocket infection, means complete system removal.
• Prosthetic valves: longer antibiotic courses, rifampicin for staphylococci and a lower threshold for surgery.
• Central line infections are covered in central line infections.

Shared principles

Timing	Typical route	Organisms
Early (joints under 3 months; valves under 12 months)	Contamination at surgery	S. aureus, Gram-negatives, coagulase-negative staphylococci
Delayed (joints 3 to 24 months)	Low-grade contamination at surgery	Coagulase-negative staphylococci, Cutibacterium acnes, enterococci
Late (joints after 24 months)	Haematogenous seeding from skin, teeth, gut or urinary tract	S. aureus, streptococci, Gram-negatives

• Coagulase-negative staphylococci and C. acnes, usually dismissed as contaminants, are real pathogens when they grow from several samples around prosthetic material.
• Rifampicin penetrates biofilm and kills slow-growing staphylococci. It is the key drug when staphylococcal infection is treated with the hardware retained. Watch its interactions: it lowers levels of warfarin, DOACs, tacrolimus, ciclosporin, azoles, many antiretrovirals and hormonal contraceptives.
• Oral step-down with highly bioavailable drugs is acceptable in bone and joint infection. OVIVA (NEJM 2019) found oral therapy non-inferior to IV for the first 6 weeks.

Prosthetic joint infection

Recognition

• Early or acute haematogenous: a hot, swollen, painful joint, wound discharge or breakdown, fever.
• Chronic or delayed: persistent pain, often without fever. Early loosening or a joint that "was never right" since surgery.
• A sinus tract communicating with the prosthesis confirms infection on its own.
• Any S. aureus bacteraemia in a patient with a prosthetic joint needs that joint examined, and aspirated if painful.

Diagnosis

The EBJIS 2021 definition sorts cases into infection unlikely, likely or confirmed. The 2018 MSIS criteria are also in use.

Test	Findings that confirm or strongly suggest infection (chronic PJI)
Sinus tract or pus around the prosthesis	Confirms
Synovial fluid white cells	Over 3,000 cells/µL or over 80% neutrophils confirms; over 1,500 cells/µL or over 65% neutrophils makes infection likely (EBJIS). Much higher cut-offs apply within 6 weeks of surgery
Cultures	The same organism in 2 or more separate samples confirms; a single positive sample makes infection likely
Alpha-defensin	Positive synovial test confirms (EBJIS)
Histology	5 or more neutrophils per high-power field in at least 5 fields confirms (EBJIS)
Implant sonication	Over 50 CFU/mL confirms
CRP	Over 10 mg/L supports; normal CRP doesn't exclude low-grade infection

• Stop antibiotics for 2 weeks before aspiration if the patient is stable.
• At revision, take 3 to 5 separate tissue samples with clean instruments. Ask for 14-day incubation when C. acnes is possible (shoulder).
• Plain X-ray may show loosening or periosteal reaction but can't distinguish septic from aseptic loosening.

Surgical strategy

Strategy	When
DAIR (debridement, antibiotics, implant retention, with exchange of modular parts)	Early post-operative or acute haematogenous infection, symptoms under 3 weeks, stable implant, healthy soft tissues, no sinus tract
One-stage exchange	Chronic infection with a known, susceptible organism and good soft tissues
Two-stage exchange	Chronic infection with a difficult or unknown organism, poor soft tissues or a sinus. Remove, place an antibiotic spacer, treat, reimplant weeks later
Long-term suppression	Patient unfit for surgery; oral antibiotic indefinitely
Resection arthroplasty or amputation	Repeated failure, severe bone or soft tissue loss

Antibiotics

• Empirical after sampling at surgery: vancomycin plus a Gram-negative agent, narrowed once cultures return.
• Staphylococci with retained implant: flucloxacillin, cefazolin or vancomycin IV for the initial phase, then rifampicin plus a fluoroquinolone (ciprofloxacin or levofloxacin), or rifampicin with another oral partner.
• Duration: 12 weeks after DAIR or one-stage exchange (DATIPO). After two-stage exchange, practice varies; DATIPO found less difference in this group.
• Pitfall: stopping at 6 weeks because "that's the standard bone infection course".

Prosthetic valve endocarditis

The diagnostic approach, Duke-ISCVID criteria and prophylaxis are in the endocarditis note. What differs with a prosthetic valve:

• Early PVE (under 12 months) is mostly staphylococci, Gram-negatives and fungi from surgery. Late PVE looks like native valve endocarditis (streptococci, S. aureus, enterococci).
• TTE is often non-diagnostic. Do TOE early, and use cardiac CT for abscess and pseudoaneurysm and FDG-PET/CT when echo is equivocal (interpret with caution in the first 3 months after surgery, when uptake counts only as a minor criterion).
• TAVI endocarditis is increasingly common, often enterococcal or staphylococcal, with high mortality.
• Antibiotics for at least 6 weeks. For staphylococcal PVE, ESC 2023 recommends flucloxacillin (or vancomycin for MRSA) with rifampicin for 6 weeks or more and gentamicin for the first 2 weeks. Monitor renal function and hearing.
• Surgery is needed more often than with native valves: valve dehiscence, paravalvular abscess or fistula, heart failure, persistent bacteraemia, large or embolising vegetations, and fungal or S. aureus PVE in many cases.
• Pitfall: a raised INR from warfarin with a mechanical valve is not a reason to delay TOE, but intracranial haemorrhage from septic emboli must be excluded before continuing full anticoagulation.

Cardiac implanted electronic device (CIED) infection

Covers pacemakers, ICDs and CRT devices. Risk is higher after generator replacement, upgrade, haematoma, early re-intervention, CKD, diabetes and anticoagulation.

Presentations

Type	Features
Pocket infection	Erythema, warmth, swelling, pain or discharge at the generator site
Erosion	Generator or lead visible through the skin. Treated as infected even if it looks clean
Lead infection or CIED endocarditis	Fever and bacteraemia, often without pocket signs; vegetations on leads or the tricuspid valve; septic pulmonary emboli

Investigations

• At least 2 sets of blood cultures before antibiotics.
• Don't aspirate the pocket. It yields little and can introduce infection.
• TOE in anyone with bacteraemia and a device. TTE misses most lead vegetations.
• FDG-PET/CT helps when the pocket looks normal and the source is unclear.
• At extraction, send the pocket tissue and lead tips for culture.

Management

• Complete system removal (generator and all leads) for any confirmed CIED infection, including isolated pocket infection and erosion. Antibiotics alone have high relapse rates.
• Percutaneous transvenous lead extraction at an experienced centre with cardiothoracic backup. The 2026 HRS consensus update, developed with AHA, APHRS, EHRA, IDSA, LAHRS, PACES and STS, sets standards for extraction facilities and covers CIED infection.
• S. aureus bacteraemia with a CIED: strongly consider extraction even with a normal pocket and no visible lead vegetation, because occult device infection is common. Gram-negative bacteraemia with a clear alternative source that clears quickly doesn't automatically need extraction.
• Antibiotics after extraction: about 7 to 14 days for pocket infection (2026 HRS update); at least 2 weeks for bacteraemia; 4 to 6 weeks for valvular endocarditis, persistent bacteraemia or metastatic infection.
• Reimplantation: first ask if a device is still needed (often not). The 2026 update says to individualise timing to clinical status and reinfection risk. Older guidance (AHA 2010, HRS 2017) used the opposite side after blood cultures had been negative for 72 hours, or about 14 days with valve vegetations. Bridge pacing-dependent patients with a temporary active-fixation lead. Consider a leadless pacemaker or subcutaneous ICD.
• Prevention: cefazolin within 60 minutes before implantation (vancomycin if MRSA colonised), avoiding pocket haematoma, and an antibacterial envelope for high-risk procedures (WRAP-IT, NEJM 2019).
• Left ventricular assist devices: driveline infections are common, usually S. aureus or Pseudomonas, and are rarely cured. Long-term suppression is typical.

Australian specifics

• The Australian Orthopaedic Association National Joint Replacement Registry tracks revisions; infection is one of the leading reasons for early revision of hip and knee replacements.
• Rheumatic heart disease means more young Aboriginal and Torres Strait Islander, Māori and Pacific people live with prosthetic valves, often mechanical, so PVE and anticoagulation decisions arise in young patients in remote settings.
• Rifampicin is TGA-registered and PBS-listed but needs liver function and interaction checks; many patients on DOACs need a switch to an alternative anticoagulant while on it.

Pitfalls

• Starting empirical antibiotics for a painful prosthetic joint in a stable patient before aspiration.
• Dismissing coagulase-negative staphylococci or C. acnes grown from several prosthetic samples as contamination.
• Using rifampicin alone, or starting it while bacteraemic with a high organism load.
• Missing the rifampicin-DOAC interaction in a patient with AF and a prosthetic joint.
• Treating a pacemaker pocket infection with antibiotics and leaving the device in.
• Aspirating a CIED pocket.
• Assuming a normal TTE excludes prosthetic valve or lead endocarditis.