Oxytetracycline Hydrochloride/Polymyxin B Sulfate

With bacterial 16S rRNA gene (rDNA) as molecular marker and by using PCR-DGGE technique, the fingerprints of bacterial community were constructed to study the effects of applying streptomycin sulfate, terramycin, and penicillin on the bacterial community in shrimp hatchery system. Within the 120 h experimental period, significant difference in the diversity of the bacterial community was observed between the treatments applied with 0.5 mg x L(-1) of test antibiotics and the control. In the control, the band patterns in 0-30 h were clustered into one clade, and those in 56-120 h were clustered into another; while in the treatments applied with test antibiotics, the band patterns in 0-56 h were clustered into one clade, and those in 72-120 h were clustered into another. After the sequencing of DGGE bands, the BLAST-N searches for sequence similarity showed great diversity of bacterial species, including culturable bacteria (mainly Sulfitobacter sp., Rhodobacteraceae sp., Photobacterium damselae, Synechoccoccus sp., Actinomycetales, Flavobacteriaceae, Filamentous photosynthetic, Mucus, and Vibrio harveyi) and some uncultured marine bacteria, among which, Rhodobacteraceae sp., Photobacterium damselae, Actinomycetales, Flavobacteriaceae, Mucus, and two unculturable bacteria were less affected by the three antibiotics, while Sulfitobacter sp., Filamentous photosynthetic, and other eight unculturable marine bacteria changed in different spatiotemporal patterns with the kinds of test antibiotics.

Numerous clinical studies have shown that biofilm formation by Staphylococcus epidermidis on the outer surface of a silicone breast implant is strongly associated with capsular contracture formation. Traditional administration of systemic antibiotics and antiseptic washing are not necessarily the most effective methods for the prevention of initial biofilm formation on implants in the clinical scenario. In this study an alternative or supplement was sought for preventing or delaying bacterial colonisation and adherence to the outer surface of a breast implant, by establishing an in vitro model for investigating this complex problem. The in vitro antimicrobial activity of several antimicrobial agents was investigated for inhibitory effects on biofilm formation by S. epidermidis.

The study consisted of two experiments. The first experiment consisted of two groups (A and B) of seven discs each whilst the second experiment was divided into three groups (C, D and E) of 14 discs each. Each group of 14 consisted of seven smooth and seven textured discs. Discs (biopsies) of each implant were individually coated with one of six different antimicrobial agents. Controls that received no agent were included in the various experimental groups. In the first experiment disc diffusion sensitivity testing was performed and inhibition zone sizes were measured. In the second experiment the discs were cultured in broth. The degree of biofilm formation was evaluated by scanning electron microscopy (SEM).

In the first in vitro experiment, all six agents showed a measurable antimicrobial effect against the biofilm-forming strain of S. epidermidis when compared to the effect against the American Type Culture Collection strain. In the second in vitro experiment, discs coated with Chloramex, Fucidin and Terramycin did not allow biofilm formation to take place for at least 7 days.

Staphylococcus epidermidis biofilm formation on the outer surface of a silicone breast implant was prevented in vitro for at least 7 days by coating with an appropriate antimicrobial agent. Further evaluation of the interaction between antimicrobial coating agents and S. epidermidis biofilm formation needs to be made before conclusions regarding the clinical scenario can be drawn.