Isolation and identification of biofilm microorganisms from silicone gastrostomy devices

Silicone gastrostomy devices (tubes and "buttons") are used extensively for long-term feeding and administration of special diets and medications. However, their potential for harboring microorganisms and possibly compromising the host largely is unknown. This study was conducted to isolate and identify the microbial species in viable biofilms attached to these devices in a pediatric cohort.

A total of 78 domains on 18 silicone gastrostomy devices (12 "buttons" and 6 tubes converted to skin level devices), previously used for feeding (3 to 47 months) in children ranging in age from 6 months to 17 years were analyzed for microbial content. Biofilms were removed from the silicone tube surfaces and inoculated into enriched nutrient media using standard procedures. Intact biofilms also were observed using scanning electron microscopy (SEM) and confocal scanning laser microscopy.

All devices analyzed in this investigation were found to exhibit biofilm growth. Of the 24 identified bacterial species, the predominant genera included Bacillus, Enterococcus, and Staphylococcus. Control studies of the tubes under SEM showed a multitude of crevices serving as niches for microbial colonization. Observation of the attached biofilm by SEM showed various biomasses with numerous morphologies.

Biofilm composition and attachment to silicone enteral access devices has not received appropriate attention previously. This study shows that devices are colonized with various bacteria and fungi posing a potential threat to patients, particularly those who are immunocompromised. These microorganisms also may play a significant role in the formation of granulation tissue and contribute to device failure.