An in vitro biofilm model to examine the effect of antibiotic ointments on biofilms produced by burn wound bacterial isolates.
OBJECTIVE
Topical treatment of burn wounds is essential as reduced blood supply in the burned tissues restricts the effect of systemic antibiotics. On the burn surface, microorganisms exist within a complex structure termed a biofilm, which enhances bacterial resistance to antimicrobial agents significantly. Since bacteria differ in their ability to develop biofilms, the susceptibility of these biofilms to topically applied antibiotics varies, making it essential to identify which topical antibiotics efficiently disrupt or prevent biofilms produced by these pathogens. Yet, a simple in vitro assay to compare the susceptibility of biofilms produced by burn wound isolates to different topical antibiotics has not been reported.


METHODS
Biofilms were developed by inoculating cellulose disks on agar plates with burn wound isolates and incubating for 24h. The biofilms were then covered for 24h with untreated gauze or gauze coated with antibiotic ointment and remaining microorganisms were quantified and visualized microscopically.


RESULTS
Mupirocin and triple antibiotic ointments significantly reduced biofilms produced by the Staphylococcus aureus and Pseudomonas aeruginosa burn wound isolates tested, as did gentamicin ointment, with the exception of one P. aeruginosa clinical isolate.


CONCLUSIONS
The described assay is a practical and reproducible approach to identify topical antibiotics most effective in eliminating biofilms produced by burn wound isolates.
Department of Surgery, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA.
Adrienne A
AA
Hammond
Kyle G
KG
Miller
Cassandra J
CJ
Kruczek
Janet
J
Dertien
Jane A
JA
Colmer-Hamood
John A
JA
Griswold
Alexander R
AR
Horswill
Abdul N
AN
Hamood
D000704:Analysis of Variance; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001414:Bacitracin / Q000627:therapeutic use; D018441:Biofilms / Q000187:drug effects* / Q000254:growth & development; D002056:Burns / Q000382:microbiology*; D004359:Drug Therapy, Combination; D005839:Gentamicins / Q000494:pharmacology; D006801:Humans; D008826:Microbial Sensitivity Tests / Q000379:methods; D016712:Mupirocin / Q000494:pharmacology; D009355:Neomycin / Q000627:therapeutic use; D009824:Ointments / Q000494:pharmacology; D011112:Polymyxin B / Q000627:therapeutic use; D011550:Pseudomonas aeruginosa / Q000187:drug effects / Q000502:physiology*; D013211:Staphylococcus aureus / Q000187:drug effects / Q000502:physiology*
D000900:Anti-Bacterial Agents; D005839:Gentamicins; D009824:Ointments; D001414:Bacitracin; D016712:Mupirocin; D009355:Neomycin; D011112:Polymyxin B