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High rate of aminoglycoside resistance among staphylococci causing prosthetic joint infection

Paloma Anguita-Alonso1, Arlen D Hanssen, Douglas R Osmon

  • 1Division of Infectious Diseases, Department of Internal Medicine, Mayo Clinic College of Medicine, Rochester, MN 55905, USA.

Clinical Orthopaedics and Related Research
|October 6, 2005
PubMed

Insights

High rates of resistance to gentamicin and tobramycin were found in staphylococci from prosthetic joint infections. This suggests alternative antibiotics may be needed for polymethylmethacrylate impregnation.

Area of Science:

  • Orthopedics
  • Infectious Diseases
  • Microbiology

Background:

  • Aminoglycosides like gentamicin and tobramycin are frequently used in polymethylmethacrylate (PMMA) for prosthetic joint infection (PJI) prophylaxis and treatment.
  • Routine susceptibility testing of staphylococci to aminoglycosides is not standard practice in the US.
  • Staphylococcal infections remain a significant challenge in orthopedic surgery, particularly around prosthetic joints.

Purpose of the Study:

  • To determine the minimum inhibitory concentrations (MICs) of gentamicin and tobramycin against staphylococcal isolates from patients with PJI.
  • To assess the prevalence of aminoglycoside resistance in these specific clinical isolates.
  • To inform future strategies for antibiotic impregnation in PMMA for PJI management.

Main Methods:

  • Bacterial isolates were obtained from patients diagnosed with prosthetic joint infection (PJI).
  • A total of 93 staphylococcal isolates were collected for susceptibility testing.
  • Minimum inhibitory values (MIVs) for gentamicin and tobramycin were determined for each isolate.

Main Results:

  • Forty-one percent of staphylococcal isolates demonstrated resistance to gentamicin.
  • Sixty-six percent of staphylococcal isolates were resistant to tobramycin.
  • Methicillin-resistant Staphylococcus aureus (MRSA) strains exhibited higher resistance rates to both gentamicin and tobramycin compared to methicillin-susceptible strains.

Conclusions:

  • A significant proportion of staphylococci causing PJI are resistant to commonly used aminoglycosides.
  • The high resistance rates, especially in MRSA, question the continued efficacy of gentamicin and tobramycin in PMMA for PJI.
  • Further research into alternative antimicrobial agents for PMMA impregnation is warranted to combat resistant staphylococcal PJI.

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