Microbial colonization of the surface of orthopedic devices for cleft lip and palate patients

Aim: Microbial colonization of the mouth in children with cleft lip and palate (CLP) is a very important issue to be known and monitored by clinicians. In fact, the obturator plates used in CLP patients, similarly to dentures, are predisposed to the accumulation of aerobic and anaerobic microorganisms, which may lead to alteration of the normal flora either of the mouth and of the nose. The aim of this study is to understand the microbial colonization that can develop on the surface of orthopedic devices. Method: Repeated samples from the internal (IS) and external surfaces (ES) of nasoalveolar moulding devices and maxillary gingivas (MG) of a unilateral cleft lip and palate child were taken with a sterile cotton swab, transferred into 1 ml of transport medium and immediately sent to the microbiology laboratory. Aliquots of 0.1 ml samples were 10-fold serially diluted and plated into selected media for Gram positive and Gram negative bacteria and for yeasts; after incubation at 36-37 °C for 48 hours, typical colonies were enumerated and calculated as cfu/ml. Matrixassisted laser desorption/ionization mass spectrometry (MALDI-TOF-SM)) for microbial identification was then performed. The samples were taken five times, once a month, and gingival swabs were also taken from parents.Results: Oral sample swabs confirmed the presence of a variety of colonizers: Corynebacterium amycolatum, Staphylococcus epidermidis, Enterococcus faecalis, Enterobacter cloacae, Stenotrophomonas maltophilia, Streptococcus gordonii, Streptococcus salivarius, Streptococcus mitis, Streptococcus parasanguis, Stafilococcus epidermidis, Candida lusitanie, Stafilococcus aureus. The most prevalent microorganisms were Enterobacter cloacae, Streptococcus mitis and Candida lusitaniae; sequential samples revealed an increasing variety of microbial species. It is interesting to note that the bacteria isolated from the MG of the child were the same of those found in the oral cavity swabs taken from the father. The presence of Candida in the last two samples was associated to concurrent clinical features, such as oral thrush symptoms. Conclusion: The palate cleft creates communication between the nasopharyngeal space and the oral cavity, predisposing to alteration of normal flora at both sites, as observed in our study. Literature data confirm that microorganisms find excellent conditions for growth on most commonly used materials for obturator prostheses (polymethil methacrylate), due to structural defects formed by the release of gases during the polymerization process. In addition, our result are in accordance with G. Evliogu et al., who claim that Candida spp. and Stafilococcus aureus biofilms may easily colonize obturator protheses and are more resistant to antimicrobial treatment than planktonic cells, individually. In this study we found that Candida species localized on the surface of the obturator plates have led to symptomatic thrush. These important medical consequences require appropriate risk management, including the need for prophylactic treatments. In conclusion, more investigations should be carried to verify the hypothesis of a microbial transmission from parents to children by means of the obturators.