Teemu J. Kinnari

Human picornavirus and coronavirus RNA in nasopharynx of children without concurrent respiratory symptoms.

The prevalence of human rhino‐, entero‐, and coronaviruses was investigated by RT‐PCR in nasopharyngeal aspirates from 107 children without concurrent respiratory symptoms. The children were admitted to the hospital for elective surgery. The parents filled a questionnaire about the occurrence of respiratory symptoms four weeks before and two weeks after the surgery. The rate of viral detection was 45% in children with related past or recent respiratory infection whereas 20% of the samples taken from children without any related past or recent respiratory infections were positive for picornavirus RNA, P = 0.008. Thirty‐one (29%) of the nasopharyngeal aspirates were positive for viral RNA, 18% for rhinovirus, and 11% for enterovirus RNA. Coronavirus RNA was not found in any of the children. Fifty‐five percent of the children with virus‐positive samples had an infection‐related diagnosis. In addition, 81% of the children with virus‐positive samples had had previously respiratory symptoms or there were concurrent respiratory symptoms in other family members. Only four of the 31 virus‐positive samples were from children without infection‐related diagnosis or recent past (or immediate future) respiratory symptoms. J. Med. Virol. 66:417‐420, 2002.

Evaluation of Quantitative Analysis of Cultures from Sonicated Retrieved Orthopedic Implants in Diagnosis of Orthopedic Infection

ABSTRACT To improve the microbiological diagnosis of device-related osteoarticular infections, we have developed a protocol based on the sonication of device samples, followed by concentration and inoculation of the sonicate in a broad variety of media in a quantitative manner. Sixty-six samples from 31 patients were included in the study (17 of them with clinical diagnosis of infection). The sonication procedure had a sensitivity of 94.1%, which is better than that of conventional cultures (88.2%). One case of contamination and six cases of unexpected positive cultures were detected (specificity of 42.8%): two of these were considered to represent true infection, while the other four were considered to be nonsignificant (corrected specificity of 50%), although the clinical importance of these isolates is questionable. When we analyzed the number of CFU, no breakpoint between significant and nonsignificant isolates could be established. Based on our results, the procedure of sonication of retrieved implants is better than conventional cultures for the diagnosis of device-related infections. The significance of some isolates in patients without clinical infection remains uncertain. However, they may become pathogens and cannot be routinely considered to be contamination.

Bacterial adherence to titanium surface coated with human serum albumin.

Hypothesis: An albumin coating on titanium implants will inhibit bacterial adhesion on the implant surface. Background: Bacterial, protein, and platelet adhesion on otologic implants and tympanostomy tubes is a major reason for implant sequelae and can eventually lead to implant removal. The role of albumin coating of the implant in prevention of protein adhesion on implant surface has already been tested by the authors. In the present study the authors examined the in vitro adherence of Staphylococcus aureus and Pseudomonas aeruginosa on an albumin-coated and uncoated titanium surface. Methods: Human serum albumin (HSA)-coated and uncoated titanium surfaces were exposed to viable S. aureus and P. aeruginosa and, after washings, photographed by fluorescence microscopy to quantify the adhered bacteria, which was stained with acridine orange. Results: Bacteria in the suspension adhered at a significantly lesser rate to the coated surfaces than to the uncoated surfaces, with overall bacterial adhesion dependent on bacterial concentration. Binding of S. aureus on HSA-coated surfaces was inhibited significantly (from 82 to 95% depending on concentration). Binding of P. aeruginosa was inhibited from 29 to 37%. Conclusion: Because albumin coating can reduce bacterial adherence on titanium surfaces in vitro, reduction is possible in bacterial contamination and infection of the HSA-coated titanium implant in vivo.

Influence of surface porosity and pH on bacterial adherence to hydroxyapatite and biphasic calcium phosphate bioceramics.

Hydroxyapatite (HA) and biphasic calcium phosphate (BCP) ceramic materials are widely employed as bone substitutes due to their porous and osteoconductive structure. Their porosity and the lowering of surrounding pH as a result of surgical trauma may, however, predispose these materials to bacterial infections. For this reason, the influence of porosity and pH on the adherence of common Gram-positive bacteria to the surfaces of these materials requires investigation. Mercury intrusion porosimetry measurements revealed that the pore size distribution of both bioceramics had, on a logarithmic scale, a sinusoidal frequency distribution ranging from 50 to 300 nm, with a mean pore diameter of 200 nm. Moreover, total porosity was 20 % for HA and 50 % for BCP. Adherence of Staphylococcus aureus and Staphylococcus epidermidis was studied at a physiological pH of 7.4 and at a pH simulating bone infection of 6.8. Moreover, the effect of pH on the zeta potential of HA, BCP and of both staphylococci was evaluated. Results showed that when pH decreased from 7.4 to 6.8, the adherence of both staphylococci to HA and BCP surfaces decreased significantly, although at the same time the negative zeta-potential values of the ceramic surfaces and both bacteria diminished. At both pH values, the number of S. aureus adhered to the HA surface appeared to be lower than that for BCP. A decrease in pH to 6.8 reduced the adherence of both bacterial species (mean 57 %). This study provides evidence that HA and BCP ceramics do not have pores sufficiently large to allow the internalization of staphylococci. Their anti-adherent properties seemed to improve when pH value decreased, suggesting that HA and BCP bioceramics are not compromised upon orthopaedic use.

Biofilm development by potentially pathogenic non-pigmented rapidly growing mycobacteria

BackgroundA study to evaluate the biofilm-development ability in three different media (Middlebrook 7H9, sterile tap water and PBS-5% glucose) was performed with 19 collection strains from 15 different species on non-pigmented rapidly growing mycobacteria (NPRGM). A microtiter plate assay was developed to evaluate the percentage of covered surface of the microtiter plate wells in different days from day 1 to day 69.ResultsAll strains were able to develop biofilm in all the tested media. Middlebrook 7H9 showed the fastest growth, followed by sterile tap water and PBS-5% glucose. A sigmoid growth curve was detected in all the strains both in Middlebrook 7H9 and in sterile tap water. A difference could be detected for Mycobacterium abscessus in tap water, where it showed faster growth than all the other strains.ConclusionBiofilm development seems to be a property of all the species of NPRGM and it depends on the nutrients present in the medium. The microtiter plate assay described here is a useful tool to evaluate differences in biofilm development among the different species of rapidly growing mycobacteria.

New method for coating tympanostomy tubes to prevent tube occlusions

OBJECTIVE tympanostomy tube insertion is currently the most common surgical procedure requiring general anesthesia performed on children. Occlusion of the tube and prolonged otorrhea through the tube are typical problems associated with the use of middle-ear ventilation tubes. In this study, a new method for coating ventilation tubes is introduced that prevents occlusion of the tube lumen by granulation tissue, blood clot or pus. METHODS human serum albumin (HSA) was used to coat standard tympanostomy tubes of different materials. Fibronectin, a typical protein in serum and exudates and one of the most adhesive glycoproteins, was used as a model representative of exudates of the ear. RESULTS when compared with the binding on uncoated tubes, the binding of fibronectin on HSA-coated tubes was inhibited from 59 to 85%, depending on the tube material used. CONCLUSIONS HSA-coating markedly reduced the binding of fibronectin on tube surfaces in vitro. The study shows the potential role of HSA-coating in preventing the adherence of foreign material to tympanostomy tubes and reducing tube occlusions.

Albumin‐Coated Tympanostomy Tubes: Prospective, Double‐Blind Clinical Study

Objectives: Coating an implant with albumin prevents adhesion of proteins, bacteria, and platelets and thus may lead to its improved and prolonged function. Previously, we have demonstrated the inhibition of binding of fibronectin, one of the most adhesive glycoproteins, on human serum albumin (HSA)‐coated tympanostomy tubes and the durability of this binding inhibition in a 8‐month trial. We have also demonstrated that the HSA coating inhibits the binding of Staphylococcus aureus and Pseudomonas aeruginosa to titanium plates. This prospective study evaluated the effect of albumin coating on tympanostomy tube sequelae and on the outcome of tympanostomized patients.

Bacterial adherence to SiO2-based multifunctional bioceramics.

The bacterial adherence onto different multifunctional silica-based bioceramics has been evaluated. Staphylococcus aureus and Staphylococcus epidermidis were chosen, as they cause the majority of the implant-related infections in this field. Two SiO2 mesoporous materials (MCM-41, SBA-15), an ordered SiO2-CaO-P2O5 mesoporous glass (OMG), and a biphasic magnetic bioceramic (BMB), were incubated with S. aureus and S. epidermidis for 90 min, and subsequently sonicated to quantify the number of adhered bacteria on each material. It was found that S. aureus and S. epidermidis (10(8) CFU/mL) adhered significantly less to BMB samples when compared to MCM-41, SBA-15, or OMG. However, when the material pores accessible for bacteria in each material were taken into account, the lowest bacterial adherence was found in MCM-41, and the highest in SBA-15. The results show that bacterial adherence is higher on mesoporous bioceramics, although this higher microbial attachment is mainly due to the intergranular porosity and grain size morphology rather than to the mesoporous structure.

Interactions of human bone cells with diamond-like carbon polymer hybrid coatings

Diamond-like carbon (DLC) coatings produced using the plasma-accelerating filtered pulsed arc discharge (FPAD) method display excellent adherence to the substrate and improve its corrosion resistance. This article reports the interactions of human osteoblastic cells with DLC and two DLC polymer hybrid (DLC-p-h) coatings deposited on smooth, matt and rough silicon wafers by the FPAD method. The DLC-p-h materials were DLC-polytetrafluoroethylene hybrid (DLC-PTFE-h) and DLC-polydimethylsiloxane hybrid (DLC-PDMS-h) coatings. The biocompatibility of the coatings was assayed by using mesenchymal stem cells, primary osteoblasts and Saos-2 cells. Human mesenchymal stem cells proliferated when cultured on DLC and DLC-PTFE-h, but their numbers diminished on DLC-PDMS-h. In all three cell types studied, phalloidin-TRITC staining disclosed cell-type organization typical of an actin cytoskeleton on DLC and DLC-PTFE-h, but minimal and disorganized stress fibers on cells cultured on DLC-PDMS-h. The microtubular cytoskeleton was similarly disorganized on DLC-PDMS-h. Cells on DLC-PDMS-h developed a peculiar form of membrane damage, with nuclear staining by propidium iodide associated with granular calcein staining of the cytoplasm. Active caspase-3 labeling was only seen in cells cultured on DLC-PDMS-h, indicating that these cells undergo apoptosis induced by defective cell adhesion. Results suggest that DLC-PDMS-h coatings might be useful in orthopedic applications where an implant or implant-facet should be protected against bone overgrowth while DLC and DLC-PTFE-h coatings might improve osseointegration.

Role of Albumin Coating of Tympanostomy Tubes: Long‐Term Clinical Evaluation

Objective: Our previous work has shown that albumin coating of tympanostomy tubes prevented adhesion of proteins or bacteria on the tube surface in vitro and in a 9‐month prospective follow‐up study. This study was continued until all tubes were extruded.