Comparison of Staphylococcal Flora in Denture Plaque and the Surface of the Pharyngeal Mucous Membrane in Kidney Transplant Recipients

Distribution and antibiotic-resistance of different Staphylococcus species identified by matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) isolated from the oral cavity

Background: The use of antibiotics in dentistry is associated with the emergence and spread of antibiotic-resistant microorganisms, including commensal staphylococci.

Methods: A total of 367 oral samples were collected, from which staphylococci were isolated and identified by using matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF). The antibiotic susceptibility of the isolates was determined and molecular characteristics for methicillin-resistant staphylococci was performed.

Results: A total of 103 coagulase-negative staphylococci (CoNS), among them S. warneri, S. haemolyticus, S. saprophyticus, S. pasteuri, S. epidermidis, S. hominis, S. xylosus, S. equorum, S. kloosii, S. succinus, S. cohnii, and S. simulans, were confirmed by MALDI-TOF. Resistance to most tested antibiotics was statistically higher in CoNS than in S. aureus isolates (P-value < 0.05). CoNS isolates showed high resistance to penicillin (S. saprophyticus 88.9%), erythromycin (S. haemolyticus 84.6%), fusidic acid (S. saprophyticus 77.8%), co-trimoxazole (S. epidermidis 71.4%), gentamicin (S. warneri 63.8%), and tetracycline (S. saprophyticus 55.6%). Multidrug resistance was largely observed, especially among S. haemolyticus and S. saprophyticus species. Methicillin-resistance in S. haemolyticus (38.5%), S. saprophyticus (22.2%) and S. aureus (13.5%) was associated with the presence of the mecA gene and SCCmec type IV or V.

Conclusion: Coagulase-negative staphylococci, especially S. haemolyticus and S. saprophyticus, seem to be a reservoir of methicillin resistance and multidrug resistance in the oral cavity.

Preliminary Clinical Data and the Comparison of the Safety and Efficacy of Autogenous Bone Grafts Versus Xenograft Implantations in Vertical Bone Deficiencies Before Dental Implant Installation

Two different techniques of vertical bone augmentation were compared to apply them to immunocompromised patients. One of them used autogenous bone graft; the other used xenograft. Thirty patients were involved in the study. Fifteen received autogenous ring shape grafts harvested from the mental region, and 15 received xenograft vertical tunnel augmentation. They have a total of 60 implants placed in the posterior region of the mandible (2 for each patient). Fixed full ceramic crowns were delivered. Two-year follow-up appointments after implant placement were made. Both autogenous bone grafts and xenografts showed similar long-term clinical regeneration outcome of vertical bone defects. Using autogenous bone rings simultaneously fixed by dental implants, the total treatment time and cost were shortened, but the traumatic reactions and complication rates were higher when compared to xenograft vertical tunnel augmentation. Due to the less traumatic character of the procedure, smaller complication rates and higher safety for the patients receiving chronic immunosuppression should avoid bone block augmentation and reap the benefits from vertical tunnel bone augmentation using xenograft materials.

Pathogenic Mechanisms and Host Interactions in Staphylococcus epidermidis Device-Related Infection

Staphylococcus epidermidis is a permanent member of the normal human microbiota, commonly found on skin and mucous membranes. By adhering to tissue surface moieties of the host via specific adhesins, S. epidermidis is capable of establishing a lifelong commensal relationship with humans that begins early in life. In its role as a commensal organism, S. epidermidis is thought to provide benefits to human host, including out-competing more virulent pathogens. However, largely due to its capacity to form biofilm on implanted foreign bodies, S. epidermidis has emerged as an important opportunistic pathogen in patients receiving medical devices. S. epidermidis causes approximately 20% of all orthopedic device-related infections (ODRIs), increasing up to 50% in late-developing infections. Despite this prevalence, it remains underrepresented in the scientific literature, in particular lagging behind the study of the S. aureus. This review aims to provide an overview of the interactions of S. epidermidis with the human host, both as a commensal and as a pathogen. The mechanisms retained by S. epidermidis that enable colonization of human skin as well as invasive infection, will be described, with a particular focus upon biofilm formation. The host immune responses to these infections are also described, including how S. epidermidis seems to trigger low levels of pro-inflammatory cytokines and high levels of interleukin-10, which may contribute to the sub-acute and persistent nature often associated with these infections. The adaptive immune response to S. epidermidis remains poorly described, and represents an area which may provide significant new discoveries in the coming years.