In Vitro Antimicrobial Activity of Phramongkutklao Hydroxyapatite Antibiotic Pellet
Thanainit Chotanaphuti MD*, Panya Surijamorn MD*, Suriya Luenam MD*, Pipat Ongnamthip MD**
Affiliation : * Department of Orthopedics, Phramongkutklao Hospital, Bangkok ** Vejthani Total Joint Replacement Center, Vejthani Hospital, Bangkok
Objective : Assess the antimicrobial activity of Phramongkutklao antibiotic hydroxyapatite pellets in vitro.
Material and Method: The selected bacteria used in the present study were the standard and drug-resistant
strains of Staphylococcus aureus and Pseudomonas aeruginosa, which are the common organisms causing
infection in Orthopedics. Phramongkutklao antibiotic hydroxyapatite pellets developed by the Orthopedics
Department, Phramongkutklao Hospital contained either Vancomycin, Fosfomycin, or Gentamycin. Each
preparation was placed on an agar plate inoculated with each bacterium. The inhibition zones were monitored
in 24 hours. Then the pellets were moved onto the new inoculated plate every day for 28 days.
Results : Compared with the control group, Phramongkutklao antibiotic hydroxyapatite pellets had good
inhibitory effect against S.aureus. Vancomycin hydroxyapatite pellets were able to maintain their activity for
28 days whereas Gentamycin hydroxyapatite pellets was effective for only three days. Fosfomycin hydroxyapatite
pellets could inhibit MSSA for 13 days and MRSA for 25 days. On the contrary, all three Phramongkutklao
antibiotic hydroxyapatite pellets had very low efficacy against P.aeruginosa.
Conclusion : Phramongkutklao antibiotic hydroxyapatite pellets were able to inhibit the growth of S. aureus
both MSSA and MRSA while the activity against P.aeruginosa needs to be developed.
Keywords : Hydroxyapatile, Antibiotic pellet, Infection
