Two modes of evolution shape bacterial strain diversity in the mammalian gut for thousands of generations.

How and at what pace bacteria evolve when colonizing healthy hosts remains unclear. Here, by monitoring evolution for more than six thousand generations in the mouse gut, we show that the successful colonization of an invader Escherichia coli depends on the diversity of the existing microbiota and the presence of a closely related strain. Following colonization, two modes of evolution were observed: one in which diversifying selection leads to long-term coexistence of ecotypes and a second in which directional selection propels selective sweeps. These modes can be quantitatively distinguished by the statistics of mutation trajectories. In our experiments, diversifying selection was marked by the emergence of metabolic mutations, and directional selection by acquisition of prophages, which bring their own benefits and costs. In both modes, we observed parallel evolution, with mutation accumulation rates comparable to those typically observed in vitro on similar time scales. Our results show how rapid ecotype formation and phage domestication can be in the mammalian gut.

Italian young doctors' knowledge, attitudes and practices on antibiotic use and resistance: A national cross-sectional survey.

OBJECTIVES: Antimicrobial resistance (AMR) is one of the major health issues worldwide. Clinicians should play a central role to fight AMR, and medical training is a pivotal issue to combat it; therefore, assessing levels of knowledge, attitudes and practices among young doctors is essential for future antimicrobial stewardship (AMS) programmes. METHODS: A nationwide, cross-sectional, multicentre survey was conducted in Italy. A descriptive analysis of knowledge and attitudes was performed, along with a univariate and multivariate analysis of their determinants. RESULTS: Overall, 1179 young doctors accessed the survey and 1055 (89.5%) completed all sections. Regarding the knowledge section of the questionnaire, almost all participants declared to know the different species of bacteria proposed, however the percentage of participants who correctly responded to clinical quizzes was 23% for the question on vancomycin-resistant enterococci (VRE), 42% on carbapenem-resistant Enterobacteriaceae (CRE), 32% on extended-spectrum ß-lactamase-producing enterobacteria (ESBL) and 27% on methicillin-resistantStaphylococcus aureus (MRSA). Similarly, 81% of participants disagreed in stating that AMR was adequately addressed during their medical training and 71% disagreed that they received the right example from their tutors. Finally, a high rate of agreement with the proposed actions to combat AMR was documented; in particular, the percentage agreement was 76% for respondents who agreed to be part of an active surveillance system or AMS programme. CONCLUSIONS: Tackling AMR should be a priority for politicians and for all health workers. Inclusion of competencies in antibiotic use in all specialty curricula is urgently needed.

[Canaud central venous catheters: 4-year experience]. / Cateteri venosi centrali di canaud: esperienza di oltre quattro anni.

BACKGROUND: The use of central venous catheters for permanent vascular access has become increasingly important because of the characteristics and the clinical problems of incident patients or patients already undergoing chronic hemodialysis. In this study a short and medium term evaluation was made of a double permanent central venous catheter positioned in the right internal jugular vein. The Canaud catheter was evaluated both from the point of view of practical use and for various technical and clinical problems. METHODS: During the observation period, July 1995 - September 1999, these catheters were used in 39 patients (mean age 72 years), 22 females and 17 males; 31% were diabetic patients and 46% were older than 75 years. Forty-five catheters were positioned with an average dwelltime of 347 days. RESULTS: Utilization was almost immediate and the resulting blood flow was suitable for all depurative techniques (blood flow more than 250 ml/min), with an average recirculation of 11.9% and an average resistance index of 0.54. Among the most serious complications during surgery a respiratory block was observed followed by the complete recovery of the patient. Some clinical complications were noted (5 venous thrombosis), as were some technical ones: 12% well as related to problems with the adapter, 24.3% to reversible thrombosis of the catheters occurred in 23 catheters in 22 patients. Infections. CONCLUSIONS: Overall Canaud catheters appear to represent a valid alternative to other more recent catheters for permanent vascular access. If necessary, they can be easily substituted due to the absence of a subcutaneous cuff.

[Permanent central venous catheters for dialysis. The situation in Piedmont-Aosta Valley]. / Cateteri venosi centrali a permanenza per dialisi. Realtà in Piemonte-Valle d'Aosta.

BACKGROUND: Permanent central venous catheters for hemodialysis have become increasingly important as vascular accesses for extracorporeal dialysis. The aim of this study was to evaluate the prevalence and various aspects of these catheters in the chronic dialysis population in Piedmont and Aosta Valley on 30-6-1998 using a multiple-choice questionnaire. METHODS: A total of 2389 patients were receiving chronic hemodialysis. Permanent central venous catheters were present in 6.2% of the population (149 patients), arteriovenous fistulas in 83.1%, vascular prostheses in 9.3% and temporary catheters in 1.4%. The site chosen for permanent catheters was the internal jugular vein in 88.6% of cases, the subclavian vein in 8.7% of cases and the femoral vein in 2.7% of cases. The double catheter is the most frequently used. In 76% of centres catheters are positioned by nephrologists. Thrombosis prophylaxis is performed in 98% of cases with heparin and the most frequently used disinfectant to dress the cutaneous exit is iodopovidone. RESULTS: This study highlights the important role played by permanent catheters. The double catheter was used in 64.4% of the entire population, confirming the greater efficiency of these catheters as reported in the literature. Operating autonomy is relative in 76.2% of centres where catheters are positioned by nephrologists who often use the collaboration of other specialists. CONCLUSIONS: The authors stress the need to reflect on the use of iodopovidone is to dress the cutaneous exit of catheters since this disinfectant is contraindicated by one of the largest manufacturers of silicone catheters owing to its harmful medium long-term effects.

[Temporary dialysis access in patients with acute renal failure. Protocols of the dialysis centers in the Piedmont and Valled'Aosta]. / Accessi temporanei per dialisi nei pazienti con IRA. Protocolli dei centri dialisi del Piemonte e della Valle d'Aosta.

BACKGROUND: A retrospective study was performed using a multiple-choice questionnaire in order to analyse the normal procedures and trends regarding the insertion and management of emergency dialysis access in patients with acute renal failure in 23 Centres in Piedment and the Aosta Valley, regions in the north of Italy with about 4.5 million inhabitants. METHODS: The observation period ran from January 1996 to July 1997. A questionnaire with 19 main questions and 90 possible multiple answers sent to 22 Centres for adults and the only pediatric centre in both regions. RESULTS: An analysis of the results showed that the most frequently used site in these regions is the subclavian vein (37.8%), followed by the internal jugular vein (32%), the femoral site (28.8%) and peritoneal catheter (1.4%); in pediatric patients, 5% used the femoral site, 10% the subclavian vein, 20% the internal jugular vein and 65% the peritoneal catheter. In 4 centres (18.2%), nephrologists do not position any type ofd access for acute renal failure. In 50% of centres, all doctors insert femoral catheters autonomously. CONCLUSIONS: Some choices, such as the subclavian route, are open to criticism and may perhaps be linked to customary procedures used by anesthetists and intensive care specialists. Some centres only have relative automomy for insertion, and lastly some types of catheters and techniques are not used. The peritoneal catheter has been abandoned by adult centres as an access in acute kidney failure patients.

Correlations between bone histopathology and serum biochemistry in uremic patients on chronic hemodialysis.

To define which noninvasive investigations are of value in predicting bone histology, we analyzed transiliac bone specimens (66 biopsies, 14 autopsies) from 80 uremic patients on chronic dialysis. Results were compared with values of different measurements of parathyroid hormone (PTH), alkaline phosphatase (APH), osteocalcin, calcitonin, baseline and post-deferroxamine (DFO) aluminium (Al),--beta 2 microglobulin, ferritin and bone mineral density. Among histomorphometric parameters, woven osteoid, active osteoblastic surface and resorption surface showed the best correlations with dynamic and biochemical marks of active bone metabolism. Among biochemical parameters, intact PTH and APH were better related to histomorphometric and dynamic bone parameters than other PTH measurements as well as osteocalcin, while calcitonin was related to no parameters. Stainable Al alone, and not total bone Al content was related to bone histology. Baseline Al was related to lamellar osteoid, while post-DFO Al was related to stainable Al. beta 2 microglobulin was positively related to active osteoid surface and ferritin was inversely related to the mineral apposition rate, while bone mineral density was related only to total bone volume. We conclude that, though definite diagnosis requires the use of histological methods, few simple biochemical parameters may offer insight to the bone metabolic status, useful to the physician in day to day clinical practice.

[Permanent vascular catheters for extracorporeal dialysis. Preliminary study: Canaud and Tesio catheters]. / Catetere vascolare a permanenza per dialisi extracorporea. Studio preliminare: cateteri di Canaud e Tesio.

The use of alternative permanent vascular accesses has recently become increasingly common. The possibility of using the catheterization of central venous vessels has therefore been taken into consideration, in particular the internal jugular vein. During an observation period of 32 months the catheterization of the internal jugular vein (IJV) was used as a definitive access in 34 patients (12 M, 22 F; mean age 67.5, mean dialytic age 56 months in 18 patients, in 16 patients the insertion was by primary intention). A total of 44 IJV catheters were used, of which 18 Tesio and 26 Canaud. The authors examined the immediate complications following insertion and the episodes occurring during the observation period, including the problem of infection. The insertion of catheters was possible in all cases. In terms of catheter function, blood flow was adequate for the various purifying techniques. No severe complications were reported: gaseous embolism, pneumothorax, hemothorax, hemomediastinum. Infection was observed in 11 patients and 13 catheters, of which 70% were mainly provoked by Staphylococcus aureus and epidermidis. During the observation period there was a drop-out of 14 patients, 11 of whom died (3 following sepsis that failed to respond to antibiotic therapy). This preliminary experiment shows that permanent jugular catheters may be regarded as a valid access for hemodialytic treatment both in patients with severe problems of vascular access and for patients who present a short-term prognosis of dialysis and life expectancy at the time of starting hemodialysis.

[Instantaneous clearances: standard heparin versus low molecular weight heparin]. / Clearances istantanee: eparina standard verso eparine a basso peso molecolare.

Standard heparin is still considered as a reference point for anticoagulation in CEC, although its use is not totally devoid of long-term and short term side effects, considering the risk of hemorrhage that patients undergo during dialysis. Numerous attempts have been made in the search for an alternative anticoagulating method. The recent discovery that low molecular weight fractions (LMWH) of standard heparin (UFH) assure the same antithrombotic effect but with a minor anticoagulating action, points to such a drug as an interesting alternative to the traditional use of heparin during dialysis. Our present task is to evaluate the purifying efficiency of different cuprophan and synthetic membranes with two LMWH and UFH, measuring the instantaneous ureic clearance of different dialysers at the start and end of each dialysis. N. 43 chronic patients were examined whilst undergoing different methods of treatment; using 12 different kinds of membrane, for a total of 22 filters. Every patient underwent a dialysis using each kind of heparin at least once, for a total of 189 dialysis. Neither the initial nor the final ureic clearances, nor the percentage of decreasing had changed by using different types of heparin and membranes with diverse thrombogenicity and ultrafiltration capacities. We may conclude from the results of the tests that the purifying efficiency of small molecules, judging from the istantaneous clearances, do not significant results compared to UFH.

[Renal insufficiency due to cholesterol embolism. 4 cases]. / Insufficienza renale da embolia colesterinica. Quattro casi.

Atheroembolic disease is a complication of atheromatous disease and is quite often misunderstood. A precise diagnosis can be made difficult, by the lack of specific tests. The first case, in which we identified this disease, resulted from a bladder biopsy, in the instance of a patient with a suspected carcinoma. The experience, with this initial patient, led us to identification of a further 3 cases, within our previous 2 years case histories. One must consider the possibility of atheroembolic disease during the differential diagnosis of acute renal failure in geriatric patients, given the serious prognosis.

Kinetics of aluminoxamine and feroxamine chelates in dialysis patients.

To achieve a rational basis for the use of deferoxamine (DFO) in aluminum (AL) -and iron (Fe)-overloaded uremic patients, important insights may be provided by the recently available micromethods to determine DFO and its metallochelates aluminoxamine (AlA) and feroxamine (FeA). With this procedure, AlA and FeA plasma kinetics were evaluated in a pilot study in 10 uremic patients during a whole week after a single DFO infusion performed during the first hour of the first standard bicarbonate hemodialysis (HD) of the week. Patients were divided into normal (n = 6) and high (n = 4) ferritin groups (1 and 2 respectively). Baseline Al concentrations were greater than 2 less than 6 in group 1 and less than 1.5 mumol/l in group 2. DFO was given at doses of 40, 20 and 10 mg/kg. AlA and FeA showed substantially different kinetics. AlA kinetics were similar in group 1 and 2: they reached their peak at the beginning of the 2nd HD, decreased during the 2nd and 3rd HD, and with the highest DFO dose still increased between the 2nd and 3rd HD. At similar pre-DFO Al values (greater than 2 less than 3.3 mumol/l), increased DFO doses produced increased AlA concentrations ranging from 95 to 40% of total plasma Al for all the week. At higher pre-DFO Al values (greater than 3.5 less than 6 mumol/l), even a DFO dose as low as 10 mg/kg was sufficient to form consistent AlA amounts (from 80 to 15% of total Al).(ABSTRACT TRUNCATED AT 250 WORDS)

[Weekly dialysis integrated with low-protein diet and essential amino acids. Preliminary data]. / Dialisi monosettimanale integrata con dieta ipoproteica e aminoacidi essenziali. Dati preliminari.

The possibility of applying a once-a-week dialysis programme supplemented with hypoproteic diet as an adequate technique for starting the uraemic patient on dialysis is examined. Thirteen patients have been so treated, 7 of them currently under treatment for a global period of observation of 46 months. At the moment dialysis began, mean glomerular filtrate was 5.14 ml/min. Once-a-week dialytic treatment with bicarbonate dialysis was associated with a hypoproteic diet of 0.5 g/kg/die of proteins, supplemented with essential amino acids. This treatment showed excellent dialytic tolerance, the values of dialysis start blood nitrogen were lower than 200 mg/dl and dialytic efficiency was compatible with a Kt/v greater than 1.1. There was no observation of any subjective or objective symptomatology that could be related to dialytic inadequacy. Taken as a whole these results make it possible to state that this type of approach permits a gradual start to dialysis and deserves further study.

Clinical and histological results of long-term management of aluminium overloading in uraemic patients with desferrioxamine.

Aluminium introxication in uraemic patients has been reported both in epidemic and sporadic forms. Desferrioxamine (DFO) results in strong Al mobilisation, but definitive treatment schedules, times of stop, and actual long-term Al removal her not been established. This study was carried out on three sporadic cases of Al intoxication treated with DFO for 3 1/2, 4 1/2 and 1 years. Clinical and laboratory parameters were employed to check the brain, bone and red cell status. Direct evaluation of Al kinetics showed that actual Al removal may be overestimated. In our experience it did not exceed 100 mg/year, and the ratio (DFO used/Al removed) decreased to 150 g/25 mg after two years of DFO, though considerable tissue deposits persisted in the patient who died after 3 1/2 years of treatment. Despite unexplained EEG worsening, neurological symptoms improved. Relapses, however, occurred after many years of DFO. Bone status improvement, at least in parathyroidectomised patients, proved to be only partial and time-related. The therapeutic effectiveness of DFO in these patients seemed to be exhausted after two years even if Al deposits had not vanished.