The Charcot Foot: An Emerging Public Health Problem for African Diabetes Patients.

Background: Although the awareness, diagnosis, management of the complications associated with diabetes have improved in African countries over the past decade, surveillance activities in Tanzania and anecdotal reports from other African countries have suggested an increased prevalence of Charcot Neuroarthropathy (CN) over the past few years. Aim: To characterize the epidemiology and the clinical burden of CN in a large diabetes population in Tanzania, and to evaluate outcomes of persons with the condition. Methods: This was a prospective analytic cohort study conducted between January 2013 through December 2015. Following informed consent, patients were followed at the outpatient clinic. Detailed clinical assessments and documented presence of diabetic peripheral neuropathy (DPN), macrovascular disease and microvascular disease were recorded. Education and counseling were part of the follow-up program. Results: 3271 ulcerations were presented at the clinic during the 3-year study period. 571 (18%) met the case definition for CN; all patients had Type 2 diabetes. The prevalence for each of the years 2013, 2014, and 2015 was 19/1192 (1.6%), 209/1044 (20%), and 343/1035 (34%), respectively; the increases in the slope of the trendline was statistically significant (P < .001). Conclusion: The prevalence of CN is increasing in the Tanzanian diabetes patient population, and is strongly associated with neuropathy. CN can lead to severe deformity, disability, and amputation. Due to the risk of limb amputation, patients with diabetes must seek immediate care if signs or symptoms appear and avoid delay in seeking medical attention. Early diagnosis of CN by caregivers is extremely important for successful outcomes.

Superficial Tissue Swabs Versus Deep Tissue Samples in the Detection of Microbiological Profile of Infected Diabetic Foot Ulcerations.

This study aimed to determine the most accurate microbiological test for the detection of micro-organisms in infected diabetic foot ulcerations in people living with type-2 Diabetes. For 20 eligible patients, a superficial tissue swab and a deep tissue sample were taken during a regular appointment at a Diabetes out-patient's Podiatry Clinic. Two specimens were collected from each wound for microbial culturing after debridement. Infected foot ulcerations were graded according to the Wagner's classification as per clinical protocol. This study found a significant difference [p = 0.028] between the two different samples. The deep tissue sample was found to be more accurate in identifying micro-organisms than the superficial swabs, although the latter is more widely used in clinical practice. Further studies are warranted to provide more evidence to clinicians on the best method to adopt when swabbing different types of diabetic foot ulcerations with different wound classification since, it is clearly still a matter of debate how to detect wound infection.

Colonic Stenting for Nonmalignant Large Bowel Obstruction to Avoid Emergency Decompressive Surgery.

Self-expanding metallic stents (SEMSs) are frequently used to decompress malignant large bowel obstruction (LBO) and avoid emergent surgery with often permanent colostomy creation. However, limited data are available on the use and outcomes of SEMS in patients with nonmalignant LBO. We present a case series of 4 patients who were found to have nonmalignant LBO for which they underwent emergent colonic stenting as a bridge to elective surgery following interdisciplinary discussion between gastroenterology, colorectal surgery, and radiology. Through each patient vignette, we illustrate the use of SEMSs as a potential alternative to emergent surgery. 2 of 4 patients avoided stoma creation at the time of surgery, and 1 patient avoided surgery altogether; overall, however, the outcomes of this approach were mixed in this series, indicating a need for further investigation to better identify the patient population that would benefit most from initial SEMS placement for decompression of nonmalignant LBO.

Clear cap-assisted luminal stenting may improve technical success in gastroduodenal and colonic obstruction.

Background Luminal stenting is safe, effective, and at times the preferred method for relieving gastrointestinal obstruction. However, stent placement is not technically feasible when lesions cannot be traversed with a guidewire, resulting in the need for more invasive methods of palliation and urgent/emergent surgical intervention. In this series, we report our experience with cap-assisted stenting to improve lumen visualization in obstructed segments of the gastrointestinal tract and salvage cases that may have otherwise resulted in technical failure. Methods A clear cap (i. e. distal attachment) was affixed to the scope tip to facilitate visualization and stenting in two cases of gastroduodenal obstruction and three cases of colonic obstruction. Indications for stent placement included malignant obstruction, diverticulitis-associated obstruction, and Crohn's disease-associated stricture. Results In this report, we demonstrate that use of a clear cap facilitated endoscopic stenting in challenging cases of malignant and benign gastroduodenal and colonic obstruction. Conclusions A clear cap for endoscopic stenting can be used in cases in which standard techniques are unsuccessful or those anticipated to be technically difficult at the outset. Cases with tortuous anatomy or particularly tight, friable, or exophytic obstructive lesions may benefit most from this novel technical modification.

Assessing the Quality of Rectal Cancer Pathology Reports in National Surgical Adjuvant Breast and Bowel Project Protocol R-04/NRG Oncology.

BACKGROUND: Accurate and comprehensive surgical pathology reports are integral to the quality of cancer care. Despite guidelines from the College of American Pathologists, variations in reporting quality continue to exist. OBJECTIVE: The aim of this study was to evaluate the quality of rectal cancer pathology reports and to identify areas of deficiency and potential sources of reporting variations. DESIGN: This is a retrospective analysis of prospectively obtained pathology reports. SETTING: This study is based at the hospitals participating in the National Surgical Adjuvant Breast and Bowel Project Protocol R-04 study. PATIENTS: Patients with rectal cancer undergoing surgical resection between July 2004 and August 2010 were included. MAIN OUTCOME MEASURES: The primary outcomes measured were the adherence to the College of American Pathologists guidelines and the impact of synoptic reporting, academic status, rural/urban setting, and hospital bed size on reporting quality. RESULTS: We identified 1004 surgical pathology reports for rectal cancer surgery from 383 hospitals and 755 pathologists. The overall adherence rate to the College of American Pathologists guidelines was 73.3%. Notable reporting deficiencies were found in several key pathology characteristics, including tumor histologic grade (reporting rate 77.8%), radial margin (84.6%), distance from the closest margin (47.9%), treatment effect (47.1%), and lymphovascular (73.1%)/perineural invasions (35.4%). Synoptic reporting use and urban hospital settings were associated with better adherence rates, whereas academic status and hospital bed size had no impact. Reporting variations existed not only between institutions, but also within individual hospitals and pathologists. There was a trend for improved adherence over time (2005 = 65.7% vs 2010 = 82.3%, p < 0.001), which coincided with the increased adoption of synoptic reporting by pathologists (2005 vs 2010, 9.4% vs 25.3%, p < 0.001). LIMITATIONS: Data were obtained from a restricted setting (ie, hospitals participating in a randomized clinical trial). CONCLUSIONS: Wide variations in the quality of pathology reporting are observed for rectal cancer. The National Accreditation Program for Rectal Cancer mandates that programs meet strict quality standards for surgical pathology reporting. Further improvement is needed in this key aspect of oncology care for patients with rectal cancer. See Video Abstract at http://links.lww.com/DCR/B238.ClinicalTrials.gov registration: NCT00058 EVALUACIÓN DE LA CALIDAD DE LOS INFORMES DE PATOLOGÍA QUIRÚRGICA EN CASOS DE CÁNCER DE RECTO DEL NSABP R-04/ ONCOLOGÍA DEL NRG: Un informe de patología quirúrgica preciso y completo es fundamental en la calidad de atención de pacientes con cáncer. A pesar de las normas establecidas por el Colegio Americano de Patología, la variabilidad en la calidad de los informes es evidente.Evaluar la calidad de los informes de patología en casos de cáncer de recto para así identificar las áreas con deficiencias y las posibles fuentes variables en los mencionados informes.Análisis retrospectivo de informes de patología quirúrgica obtenidos prospectivamente.Hospitales que participan del Protocolo del Estudio Nacional R-04 como Adyuvantes Quirúrgicos de Mama e Intestino.Todos aquellos pacientes con cáncer de recto sometidos a resección quirúrgica entre Julio 2004 y Agosto 2010.Cumplimiento de las normas del Colegio Americano de Patología, del impacto de los informes sinópticos, del estado académico, del entorno rural / urbano y el número de camas hospitalarias en en la calidad de los informes.Identificamos 1,004 informes de patología quirúrgica en casos de cirugía en cáncer de recto en 383 hospitales y 755 patólogos. La tasa general de adherencia a las directivas del Colegio Americano de Patología fue del 73.3%. Se encontraron deficiencias notables en los informes en varias características patológicas clave incluidos, el grado histológico del tumor (tasa de informe 77.8%), margenes radiales (84.6%), distancia del margen más cercano (47.9%), efecto del tratamiento (47.1%) invasión linfovascular (73.1 %) / invasion perineural (35.4%). El uso de informes sinópticos y los entornos hospitalarios urbanos se asociaron con mejores tasas de adherencia, mientras que el estado académico y el número de camas hospitalarias no tuvieron ningún impacto. Hubo variaciones en los informes no solo entre instituciones, sino también dentro de hospitales y patólogos individuales. Hubo una tendencia a una mejor adherencia a lo largo del tiempo (2005 = 65.7% v 2010 = 82.3%, p < 0.001), que coincidió con la mayor adopción de informes sinópticos por parte de los patólogos (2005 v 2010, 9.4% v 25.3%, p < 0.001)Datos obtenidos de un entorno restringido (es decir, hospitales que participan en un ensayo clínico aleatorizado).Se observaron grandes variaciones en la calidad de los informes de patología quirúrgica en casos de cáncer de recto. El Programa Nacional de Acreditación para Cáncer de Recto exige que los programas cumplan con estrictos estándares de calidad para los informes de patología quirúrgica. Se necesita una mejoría adicional en este aspecto clave de la atención oncológica para pacientes con cáncer de recto. Video Resumen en http://links.lww.com/DCR/B238.Registro de Clinical Trials.gov: NCT00058.

Peripheral vascular changes in the lower limbs following cocaine abuse.

Background: Worldwide, substance use disorder is on the rise, especially amongst the young generation. Although cocaine-induced cardiovascular and cerebrovascular events are well documented, knowledge about the relationship of cocaine use and its effect on arterial perfusion in the lower limbs is scarce.Objective: This study sought to investigate the relationship between cocaine use and peripheral arterial disease.Methods: The study population comprised 30 subjects' dependent on cocaine, smoking and alcohol [Group A] and another 30 subjects dependent on smoking and alcohol only [Group B]. A comprehensive lower limb vascular assessment was conducted utilizing pulse palpation, Doppler spectral waveform analysis, Ankle brachial pressure index (ABPI) and Toe brachial pressure index (TBPI) to determine the arterial perfusion status in the lower limbs.Results: Group A had lower ABPIs and TBPIs than Group B suggesting poorer vascular perfusion in lower limbs. Furthermore, a larger percentage of Group A had monophasic/continuous waveforms of all three pedal pulses compared to Group B. Conversely there was a higher percentage in Group B with biphasic/triphasic waveforms compared to Group A implying better vascular perfusion.Conclusion: In this study, cocaine use was associated with diminished arterial perfusion of the lower limbs suggesting that cocaine use has the potential to increase the risk of peripheral arterial disease. Regular vascular foot screening is warranted if foot complications are to be avoided.

Operative Incision and Drainage for Perirectal Abscesses: What Are Risk Factors for Prolonged Length of Stay, Reoperation, and Readmission?

BACKGROUND: Perirectal abscess is a common problem. Despite a seemingly simple disease to manage, clinical outcomes of perirectal abscesses can vary significantly given the wide array of patients who are susceptible to this disease. OBJECTIVE: Our aims were to evaluate the outcomes after operative incision and drainage for perirectal abscess and to examine factors associated with length of stay, reoperations, and readmissions. DESIGN: This was a retrospective analysis of the National Surgical Quality Improvement Program database. SETTINGS: The study was conducted with hospitals participating in the surgical database. PATIENTS: Adult patients undergoing outpatient perirectal abscess procedures from 2011 through 2016 were included. MAIN OUTCOME MEASURES: Study outcomes were length of stay, reoperation, and readmission. RESULTS: We identified 2358 patients undergoing incision and drainage for perirectal abscesses. Approximately 35% of patients required hospital stay. Reoperations occurred in 3.4%, with median time to reoperation of 15.5 days. The majority of reoperations (79.7%) were performed for additional incision and drainage. Readmissions rate was 3.0%, with median time to readmission of 10.5 days. Common indications for readmissions included recurrent/persistent abscess (41.4%) and fever/sepsis (8.6%). Risk factors for hospitalization in multivariable analysis were preoperative sepsis, bleeding disorder, and non-Hispanic black and Hispanic races. For reoperations, risk factors included morbid obesity, preoperative sepsis, and dependent functional status. Lastly, for readmissions, female sex, steroid/immunosuppression, and dependent functional status were significant risk factors. LIMITATIONS: The study was limited by its retrospective analysis and potential selection bias in decisions on hospital stay, reoperation, and readmission. CONCLUSIONS: Suboptimal outcomes after outpatient operative incision and drainage for perirectal abscesses are not uncommon in the United States. In the era of value-based care, additional work is needed to optimize use outcomes for high-risk patients undergoing perirectal incision and drainage. Strategies to prevent inadequate drainage at the time of the initial operative incision and drainage (ie, use of imaging modalities and thorough examination under anesthesia) are warranted to improve patient outcomes. See Video Abstract at http://links.lww.com/DCR/B229. INCISIÓN Y DRENAJE QUIRÚRGICOS DE ABSCESOS PERIRRECTALES: CUALES SON LOS FACTORES DE RIESGO PARA UNA ESTADÍA PROLONGADA, REINTERVENCIÓN Y READMISION?: Los abscesos perirrectales son un problema frecuente. A pesar que parecen ser una afección aparentemente simple de manejar, los resultados clínicos de la incisión y drenaje quirúrgicos pueden variar significativamente dada la amplia variedad de pacientes susceptibles de sufrir esta afección.Evaluar los resultados después de la incisión y el drenaje quirúrgicos de un absceso perirrectal y analizar los factores asociados con la duración de la hospitalización, la reoperación y la readmisión.Análisis retrospectivo de la base de datos del Programa Americano de Mejora de la Calidad Quirúrgica.Hospitales que participan en la base de datos quirúrgica.Pacientes adultos sometidos a incisión y drenaje quirúrgico ambulatorio de un absceso perirrectal desde 2011 hasta 2016.Los resultados del estudio fueron la duración de la hospitalización, la reoperación y el reingreso.Fueron estudiados 2,358 pacientes sometidos a incisión y drenaje por abscesos perirrectales. Aproximadamente el 35% de los pacientes requirieron hospitalización. Las reoperaciones ocurrieron en 3.4% con una mediana de tiempo de reoperación de 15.5 días. La mayoría de las reoperaciones (79.7%) se realizaron para una incisión y drenaje adicionales. La tasa de reingreso fue del 3.0% con una mediana de tiempo de reingreso de 10.5 días. Las indicaciones comunes para los reingresos incluyeron abscesos recurrentes / persistentes (41.4%) y fiebre / sepsis (8.6%). Los factores de riesgo para la hospitalización en el análisis multivariable fueron sepsis preoperatoria, trastorno hemorrágico, raza negra no hispánica y raza hispana. Para las reoperaciones, los factores de riesgo incluyeron obesidad mórbida, sepsis preoperatoria y estado funcional dependiente. Por último, para los reingresos, el sexo femenino, uso de corticoides / inmunosupresores y un estadío funcional dependiente fueron factores de riesgo significativos.Análisis retrospectivo y posible sesgo de selección en las decisiones sobre hospitalización, reoperación y reingreso.Un resultado poco satisfactorio después de la incisión quirúrgica el drenaje de abscesos perirrectales ambulatoriamente no son infrecuentes en los Estados Unidos. En la era de la atención basada en los resultados, se necesita mucho más trabajo para optimizar los mismos en pacientes de alto riesgo sometidos a incisión y drenaje perirrectales. Las estrategias para prevenir el drenaje inadecuado en el momento de la incisión quirúrgica inicial y el drenaje (es decir, el uso de modalidades de imágenes, un examen completo bajo anestesia) son una garantía para mejorar los resultados en estos pacientes. Consulte Video Resumen en http://links.lww.com/DCR/B229.

The progression rate of peripheral arterial disease in patients with intermittent claudication: a systematic review.

BACKGROUND: Intermittent claudication (IC) is the most common symptom of peripheral arterial disease and is generally treated conservatively due to limited prognostic evidence to support early revascularisation in the individual patient. This approach may lead to the possible loss of opportunity of early revascularisation in patients who are more likely to deteriorate to critical limb ischaemia. The aim of this review is to evaluate the available literature related to the progression rate of symptomatic peripheral arterial disease. METHODS: We conducted a systematic review of the literature in PubMed and MEDLINE, Cochrane library, Elsevier, Web of Science, CINAHL and Opengrey using relevant search terms to identify the progression rate of peripheral arterial disease in patients with claudication. Outcomes of interest were progression rate in terms of haemodynamic measurement and time to development of adverse outcomes. Two independent reviewers determined study eligibility and extracted descriptive, methodologic, and outcome data. Quality of evidence was evaluated using the Cochrane recommendations for assessing risk of bias and was reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. RESULTS: Seven prospective cohort studies and one retrospective cohort study were identified and included in this review with the number of participants in each study ranging from 38 to 1244. Progression rate reports varied from a yearly decrease of 0.01 in ankle-brachial pressure index (ABPI) to a yearly decrease ABPI of 0.014 in 21% of participants. Quality of evidence ranged from low to moderate mostly due to limited allocation concealment at recruitment and survival selection bias. CONCLUSIONS: Progression of PAD in IC patients is probably underestimated in the literature due to study design issues. Predicting which patients with claudication are likely to deteriorate to critical limb ischaemia is difficult since there is a lack of evidence related to lower limb prognosis. Further research is required to enable early identification of patients at high risk of progressing to critical ischaemia and appropriate early revascularisation to reduce lower limb morbidity.

Diabetes foot screening: Challenges and future strategies.

BACKGROUND: Healthcare options for people with diabetes is still not uniform both within and between countries. This is particularly evident for diabetic foot disease. The number of existing documents/guidelines, together with discrepancies which exist between different organizations or countries can lead to confusion for both practicing health care professionals and new countries or organizations who are in the process of developing local clinical guidelines. This study was aimed at exploring different stakeholder perspectives with a view to develop and introduce culturally competent foot screening guidelines. METHODS: A phenomenological study which incorporated non-structured interviews with eleven local stakeholders and experts related to the field were conducted to explore interviewees' perspectives regarding foot screening guidelines in Malta. FINDINGS: Qualitative analysis identified 3 key themes from the data highlighting barriers to the implementation of diabetes foot screening guidelines. These focused on organizational factors, healthcare professional factors and patient factors. CONCLUSION: Current procedures related to diabetes foot screening has shortcomings. The findings of this study clearly highlight the need for change in current practices if effective diabetic foot screening is to be offered. Recommendations from this study are relevant to other countries especially those who share same cultures and practices. Making changes today and implementing them in the appropriate manner could make a world of difference in diabetes foot care.

Comparison of in vivo vs. frozen vs. Thiel cadaver specimens in visualisation of anatomical structures of the ankle on proton density Magnetic Resonance Imaging (MRI) through a visual grading analysis (VGA) study.

PURPOSE: The use of cadavers for medical education purposes and for radiology research methodologies which involve subjective image quality evaluation of anatomical criteria is well documented. The aim of this study was to quantify the impact of cadaver tissue preservation in producing MR images that are representative of living tissue by comparing the visualisation of anatomical structures of the ankle obtained from live and cadaver (fresh frozen and Thiel embalmed) specimens through a visual grading analysis (VGA) study. METHODS: A VGA study was conducted on an image data set consisting of 4 coronal proton density weighted (PDw) sequences obtained from ankles of a live patient and those of a cadaveric specimen, of which the right ankle was frozen and the left Thiel embalmed. RESULTS: Comparison of the image quality scores obtained from: the live patient vs. the Thiel specimen indicate a significant difference (p ≤ 0.05) between the scores in favour of the Thiel specimen; between the live patient vs. the frozen specimen indicate a significant difference (p ≤ 0.05) in favour of the frozen specimen and between the frozen vs. the Thiel specimen indicate a significant difference (p ≤ 0.05) in favour of the Thiel specimen. CONCLUSIONS: The advantages of the use of cadavers (frozen or Thiel embalmed) has been shown to also apply for use with proton density (PD) MR imaging. The preservation of cadavers especially using Thiel is a suitable alternative for MRI optimisation and protocol development purposes.

Mapping HA-tagged protein at the surface of living cells by atomic force microscopy.

Single-molecule force spectroscopy using atomic force microscopy (AFM) is more and more used to detect and map receptors, enzymes, adhesins, or any other molecules at the surface of living cells. To be specific, this technique requires antibodies or ligands covalently attached to the AFM tip that can specifically interact with the protein of interest. Unfortunately, specific antibodies are usually lacking (low affinity and specificity) or are expensive to produce (monoclonal antibodies). An alternative strategy is to tag the protein of interest with a peptide that can be recognized with high specificity and affinity with commercially available antibodies. In this context, we chose to work with the human influenza hemagglutinin (HA) tag (YPYDVPDYA) and labeled two proteins: covalently linked cell wall protein 12 (Ccw12) involved in cell wall remodeling in the yeast Saccharomyces cerevisiae and the ß2-adrenergic receptor (ß2-AR), a G protein-coupled receptor (GPCR) in higher eukaryotes. We first described the interaction between HA antibodies, immobilized on AFM tips, and HA epitopes, immobilized on epoxy glass slides. Using our system, we then investigated the distribution of Ccw12 proteins over the cell surface of the yeast S. cerevisiae. We were able to find the tagged protein on the surface of mating yeasts, at the tip of the mating projections. Finally, we could unfold multimers of ß2-AR from the membrane of living transfected chinese hamster ovary cells. This result is in agreement with GPCR oligomerization in living cell membranes and opens the door to the study of the influence of GPCR ligands on the oligomerization process.

Unravelling of a mechanism of resistance to colistin in Klebsiella pneumoniae using atomic force microscopy.

OBJECTIVES: In this study we focused on the mechanism of colistin resistance in Klebsiella pneumoniae. METHODS: We used two strains of K. pneumoniae: a colistin-susceptible strain (K. pneumoniae ATCC 700603, KpATCC) and its colistin-resistant derivative (KpATCCm, MIC of colistin 16 mg/L). We performed a genotypic analysis based on the expression of genes involved in LPS synthesis and L-Ara4N moiety addition. We also explored the status of the mgrB gene. Then, a phenotypic analysis was performed using atomic force microscopy (AFM). The Young modulus was extracted from force curves fitted using the Hertz model, and stiffness values were extracted from force curves fitted using the Hooke model. RESULTS: We failed to observe any variation in the expression of genes implicated in LPS synthesis or L-Ara4N moiety addition in KpATCCm, in the absence of colistin or under colistin pressure (versus KpATCC). This led us to identify an insertional inactivation/mutation in the mgrB gene of KpATCCm. In addition, morphology results obtained by AFM showed that colistin removed the capsule from the susceptible strain, but not from the resistant strain. Nanomechanical data on the resistant strain showed that colistin increased the Young modulus of the capsule. Extend force curves recorded on top of the cells allowed us to make the following hypothesis about the nanoarchitecture of the capsule of the two strains: KpATCC has a soft capsule consisting of one layer, whereas the KpATCCm capsule is harder and organized in several layers. CONCLUSIONS: We hypothesize that capsular polysaccharides might be implicated in the mechanism of colistin resistance in K. pneumoniae, depending on its genotype.

Nanoscale effects of caspofungin against two yeast species, Saccharomyces cerevisiae and Candida albicans.

Saccharomyces cerevisiae and Candida albicans are model yeasts for biotechnology and human health, respectively. We used atomic force microscopy (AFM) to explore the effects of caspofungin, an antifungal drug used in hospitals, on these two species. Our nanoscale investigation revealed similar, but also different, behaviors of the two yeasts in response to treatment with the drug. While administration of caspofungin induced deep cell wall remodeling in both yeast species, as evidenced by a dramatic increase in chitin and decrease in ß-glucan content, changes in cell wall composition were more pronounced with C. albicans cells. Notably, the increase of chitin was proportional to the increase in the caspofungin dose. In addition, the Young modulus of the cell was three times lower for C. albicans cells than for S. cerevisiae cells and increased proportionally with the increase of chitin, suggesting differences in the molecular organization of the cell wall between the two yeast species. Also, at a low dose of caspofungin (i.e., 0.5× MIC), the cell surface of C. albicans exhibited a morphology that was reminiscent of cells expressing adhesion proteins. Interestingly, this morphology was lost at high doses of the drug (i.e., 4× MIC). However, the treatment of S. cerevisiae cells with high doses of caspofungin resulted in impairment of cytokinesis. Altogether, the use of AFM for investigating the effects of antifungal drugs is relevant in nanomedicine, as it should help in understanding their mechanisms of action on fungal cells, as well as unraveling unexpected effects on cell division and fungal adhesion.

Imaging living cells surface and quantifying its properties at high resolution using AFM in QI™ mode.

Since the last 10 years, AFM has become a powerful tool to study biological samples. However, the classical modes offered (imaging or tapping mode) often damage sample that are too soft or loosely immobilized. If imaging and mechanical properties are required, it requests long recording time as two different experiments must be conducted independently. In this study we compare the new QI™ mode against contact imaging mode and force volume mode, and we point out its benefit in the new challenges in biology on six different models: Escherichia coli, Candida albicans, Aspergillus fumigatus, Chinese hamster ovary cells and their isolated nuclei, and human colorectal tumor cells.

Nanoscale analysis of the effects of antibiotics and CX1 on a Pseudomonas aeruginosa multidrug-resistant strain.

Drug resistance is a challenge that can be addressed using nanotechnology. We focused on the resistance of the bacteria Pseudomonas aeruginosa and investigated, using Atomic Force Microscopy (AFM), the behavior of a reference strain and of a multidrug resistant clinical strain, submitted to two antibiotics and to an innovative antibacterial drug (CX1). We measured the morphology, surface roughness and elasticity of the bacteria under physiological conditions and exposed to the antibacterial molecules. To go further in the molecules action mechanism, we explored the bacterial cell wall nanoscale organization using functionalized AFM tips. We have demonstrated that affected cells have a molecularly disorganized cell wall; surprisingly long molecules being pulled off from the cell wall by a lectin probe. Finally, we have elucidated the mechanism of action of CX1: it destroys the outer membrane of the bacteria as demonstrated by the results on artificial phospholipidic membranes and on the resistant strain.