Sensitivity of bacterial biofilms and planktonic cells to a new antimicrobial agent, Oxsil 320N.

The effective concentrations of disinfectants were determined for planktonic bacteria using the norms EN 1040 and NF T 72-150. This concentration corresponds to biocide efficacy after 5 min of contact, followed by neutralization. However, micro-organisms often colonize a substratum and form microcolonies or biofilms where they are enclosed in exopolymer matrices. Biofilms are commonly resistant to a broad range of antimicrobial agents, and resistance mechanisms involve exopolymer matrices, changes in gene expression and metabolic alterations. Due to these different resistance mechanisms, it is difficult to select and titrate antimicrobial agents to be effective against biofilms. In this context, SODIFRA developed a new disinfectant, Oxsil 320N (French patent 94 15 193). Oxsil 320N is an association of three active principles: hydrogen peroxide, acetic acid/peracetic acid and silver. This biocide was tested on planktonic bacteria and on 24-h biofilms formed on AISI 304 stainless steel surfaces. The effective concentration of Oxsil 320N was also determined on biofilms using SODIFRA recommendations (without neutralization of the biocide). Data showed that the antimicrobial efficacy measured on planktonic bacteria is not a reliable indicator of performance when biofilm is present. When biofilms were exposed to Oxsil 320N, the concentration needed to achieve a 10(5)-fold decrease in concentration was 10 times higher than that for bacterial suspensions (0.313% Oxsil 320N). An effective concentration of Oxsil 320N of 3.13% was required.

Evaluation of the coulter LH 750 haematology analyzer compared with flow cytometry as the reference method for WBC, platelet and nucleated RBC count.

The Coulter LH 750 is a new haematology analyser with several new features: a count of nucleated red blood cells (NRBCs), automated WBC correction in presence of a flag indicating a cellular interference and a lower incidence of platelet or WBC interference flags when compared with the GEN.S, our current instrument. We had three main goals in our study: evaluating the LH 750 WBC counts when a GEN.S flag suggests a risk of WBC interference, ascertaining whether the platelet counts not flagged by the LH 750 were accurately assessed in samples flagged by the GEN.S and evaluating the NRBC assay provided by the LH 750. Flow cytometry, using CD45 and CD41, respectively for WBC and platelet labelling, was used as a reference method to assess the accuracy of the LH 750 counts. NRBC were identified by double labelling with propidium iodide (PI) and CD45, NRBCs being CD45-/PI+. A significant relationship was found between LH 750 and flow cytometric WBC counts, whether a WBC correction was made by the LH 750 (r = 0.9809, n = 54) or not (r = 0.9901, n = 23). A highly significant relationship was observed for platelets not only in the range from 0 to 450 x 10(9)/l (r = 0.981, n = 108) but also in cases of thrombocytopenia (range: 0-80 x 10(9)/l; r = 0.956, n = 51). In samples with NRBCs, the NRBC percentages given by the LH 750 and by flow cytometry were highly correlated (r = 0.977, n = 60) and WBC counts were accurate. In conclusion, the reduction in flagging by the LH 750, the accuracy of the results, and the availability of a NRBC count, constitute major advantages.

[Compared viability of planctonic bacteria and bacteria in biofilms by flow cytometry]. / Comparaison de la vitalité des bactéries libres et des bactéries en biofilm par cytométrie en flux.

Study of biofilms adhering to various surfaces shows the presence of several layers of cells. A small percentage can grow immediately. Are the others viable? These cells are in a resting phase and exhibit a metabolic gradient through the depth of the biofilm. In order to assess the health hazard of active recovery of these resting cells, we studied biofilms with two fluorochromes: a fluorescein diacetate derivative, CDF, which detects esterase activity and gives a green fluorescence to cells, and propidium iodide, IP, which enters cells with injured membranes and gives a red fluorescence to nucleic acids. Confocal microscopy can be used to localized red and green cells at various depths in biofilms but flow cytometry is necessary for a semi-quantitative analysis. We focused on parameters required to obtain valid flow cytometry results. After elimination of bacterial and glycocalyx autofluoresce and choosing non-toxic marker concentrations flow cytometry revealed a large proportion of double-marked cells, i.e. cells exhibiting esterase synthesis and membrane injuries. The question is whether these cells are a public health hazard. Can these cells repair their injuries and recover viability when they leave the biofilm? Do they recover metabolic activity, virulence, and sensitivity to antibacterials? Flow cytometry enabled the identification of four levels of viability in oral streptococci biofilms.

[Spinal cord compression caused by extramedullary hematopoiesis foci in the course of thalassemia]. / Compression médullaire par des foyers d'hématopoïèse extra médullaire au cours de la thalassémie.

BACKGROUND: Extramedullary haematopoiesis is a physiological response to chronic anemia, observed frequently during homozygous thalassemia. It is usually asymptomatic but can be manifested by compression of adjacent organs, particularly the spinal cord. CASE REPORT: A 44-year-old woman diagnosed with thalassaemia intermedia, was admitted for difficulties to walk and sphincter disturbances. Neurologic examination suggested spinal cord compression, which is confirmed by dorso-lumbar resonance magnetic imaging. The histology obtained by laminectomy led to the diagnosis of extramedullary hematopoiesis related to thalassemia. A radiotherapy enabled with good outcome. DISCUSSION: Spinal cord compressions by extramedullary hematopoiesis during thalassemia are uncommon (75 cases in the literature) but can induce severe sequelae if the diagnostic is not rapidly obtained. Magnetic resonance imaging is the gold standard allowing precise diagnosis and spreading of extramedullary hematopoiesis. Radiotherapy and more recently hydroxyurea are the first line treatment. CONCLUSION: This observation recalls that extramedullary hematopoiesis is a differential diagnostic of spinal cord compression in patients with thalassemia. A screening of paravertebral localization of extramedullary hematopoiesis should be performed in high risk thalassemic patients.

Evaluation of biohazards in dehydrated biofilms on foodstuff packaging.

Plastic materials used for food packaging are clean but not sterile when the food is just packaged. Accidental wet contamination may occur at every moment between packaging and opening by the consumer: on polyethylene (PET), bacteria may adhere strongly and constitute a biofilm in less than 24 h. By rolling on themselves, PET sheets may contaminate food. We tried to show that contact with salted foodstuffs favoured microbial recovery. Four strains were chosen to perform biofilms on PET: Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa and Escherichia coli. Biofilms were dried up 24 h. Biofilm bacteria were stressed by adhesion, by starvation and by dehydration. However, they were capable of recovery in salted solutions or media, probably because one (or more) stress protected them against another stress. Stress was demonstrated by stress protein production, by mean of electrophoresis, and membrane lesions by mean of flow cytometry. Stress recovery was performed in aqueous salted solutions or salted brain-heart infusion with NaCl 9, 15, 20 and 30 g/l. Staphylococci were more sensitive to these stresses and recovery was a function of salt concentration. Gram-negative bacteria were little affected by stresses; salt effects were less important. If all these biofilms were capable of recovery from stresses in salted media, flexible PET could possibly lead to a health hazard when it is used for wet salt meats, e.g.

[Prevention of cariogenic dental plaque. Study of the structures implicated in the adhesion and coaggregation in Streptococcus mutans and Streptococcus sobrinus]. / Prévention de la plaque dentaire cariogène étude des structures impliquées dans l'adhésion et la coagrégation chez Streptococcus mutans et Streptococcus sobrinus.

Cariogenic dental plaque may be assimilated to a biofilm resulting from the adhesion of S. mutans, then from the coaggregation of other streptococci, or other genus. We used a static monospecific biofilm model. Supports or bacteria were treated with inhibitors before adhesion in order to clarify the nature of adhesins responsible for the primary adhesion of S. mutans and S. sobrinus on Tygon. To determine the bindings of coaggregation, inhibitors were applied on one-day-old biofilms. Analysis of effects were performed by automatic inoculator Spiral (Interscience) for microbiological methods, and by SEM JEOL 5400 LV for microscopic methods. In the aim of preventing adhesion and coaggregation, different traps were assayed:sugars, chemical inhibitors such as F- and EDTA salts. Of these, only the latter showed efficiency. This confirmed the role of bivalent mineral ions and electrostatic attraction forces in the adhesion and coaggregation of streptococci.

[An unusual tumor of the larynx: malignant fibrous histiocytoma. Apropos of a case. Review of the literature]. / Une tumeur exceptionnelle du larynx: l'histiocytome fibreux malin. A propos d'une observation et revue de la littérature.

On the basis of one case, the authors report about an exceptional tumor of the larynx: malignant fibrous histiocytoma. This tumor, belonging to the soft-tissue sarcomas, usually develops in the limbs. The histological diagnosis is still difficult, in spite of the help provided by immunocytochemistry and fine structural analysis. A histological grading associated to other deciding prognostic factors, such as the size and depth of the tumor and the quality of exeresis, would demonstrate a prognostic correlation. The evolution is characterized by frequent local recurrence and metastases. The treatment is mainly surgical, with as extensive an exeresis as possible at once. Radiation therapy and chemotherapy, though often associated, have not decisively proven their value.

[Variations in the calcaneo-fibular ligament (lig. calcaneofibulare). Application to the kinematics of the ankle]. / Variations du ligament calcaneo-fibulaire (lig. calcaneofibulare). Applications à la cinématique de la cheville.

The authors observe variations in the calcaneo-fibular ligament because this ligament controls two articulations, the talo-crural and the subtalar. This study is based on the dissection of the ankle of 20 specimens. The calcaneo-fibular ligament is reinforced by the ventral and lateral talo-calcaneus ligaments with variations. 3 types of disposition have been described. Type A: A lateral talo-calcaneal ligament reinforces the calcaneo-fibular ligament. These two ligaments are divergent on the proximal, medial, or distal part. Type B: There is an independent lateral talo-calcaneal ligament forward of the calcaneo-fibular ligament. Type C: A ventral talo-calcaneal ligament is observed, parallel to the interosseous ligament. The authors consider the consequences of variation in the lateral ligaments of the ankle for the functioning of the tibio-tarsal articulation, the subtalar articulation and the astragalo-scaphoid articulation in order to propose specific radiographic examination of the kinematics of the ankle.

Anatomic basis of a superior approach to the acetabulum with osteotomy of the ala of the ilium.

This study demonstrates the importance of a superior approach to acetabulum with intrapelvic osteotomy of the iliac ala in certain fractures of the acetabulum. This study is based on the dissection of 15 formolized and 5 frozen subjects, the surgical treatment of 17 acetabular fractures, and the performances of 2 Chiari-type osteotomies and 2 Salter-type osteotomies. We investigated the gluteus medius muscle and its pedicle in relation to the iliac ala. Landmarks for the osteotomy lines and the gluteal pedicles are defined in terms of the requirements of different surgical approaches. The superior approach for acetabular fractures was made using a skin incision of Smith-Petersen type. The underlying principle is the performance of an intrapelvic osteotomy of the iliac ala, the anterosuperior part of the ala being tilted outward and backward and pedicled on the gluteal muscles. This provides intra- and extrapelvic exposure of the acetabular walls. The advantages and drawbacks of this route of approach in surgery of the pelvic girdle are discussed in terms of the types of fracture treated and tumoral locations. The anatomic findings are illustrated from traumatology and tumoralpathology. This approach seems particularly suitable for acetabular fractures interrupting the pelvic ring.

[Study of the vascular segmentation of the spleen]. / Contribution à l'étude de la segmentation vasculaire de la rate (lien).

An experimental study of the spleen segmentary vascularisation was conducted by the "injection-corrosion" technique. Most often was found the well known existence of two lobes, each being divided into two segments, separated by asvascular planes. However we stress the possibility of deviation from this schema, either by the existence of supernumerary polar arteries, or by anomalies in the distribution of segmental arteries.