The Role of Molar Mass in Achieving Isotropy and Inter-Layer Strength in Mat-Ex Printed Polylactic Acid.

There has been extensive research in the field of material-extrusion (Mat-Ex) 3D printing to improve the inter-layer bonding process. Much research focusses on how various printing conditions may be detrimental to weld strength; many different feedstocks have been investigated along with various additives to improve strength. Surprisingly, there has been little attention directed toward how fundamental molecular properties of the feedstock, in particular the average molar mass of the polymer, may contribute to microstructure of the weld. Here we showed that weld strength increases with decreasing average molar mass, contrary to common observations in specimens processed in more traditional ways, e.g., by compression molding. Using a combination of synchrotron infra-red polarisation modulation microspectroscopy measurements and continuum modelling, we demonstrated how residual molecular anisotropy in the weld region leads to poor strength and how it can be eradicated by decreasing the relaxation time of the polymer. This is achieved more effectively by reducing the molar mass than by the usual approach of attempting to govern the temperature in this hard to control non-isothermal process. Thus, we propose that molar mass of the polymer feedstock should be considered as a key control parameter for achieving high weld strength in Mat-Ex.

Inappropriate use of carbapenems in an internal medicine ward: Impact of a carbapenem-focused antimicrobial stewardship program.

PURPOSE: Carbapenem consumption is a major driver for selection and spread of carbapenem-resistant Enterobacterales (CRE). We assessed the impact of a carbapenem-focused multimodal antimicrobial stewardship program (ASP) in the internal medicine unit of a medium-size acute-care hospital. METHODS: We compared the percentage of inappropriate carbapenem prescriptions and the proportion of carbapenem treated patients registered in a 12-month pre-intervention and in a 24-month post-intervention period by using an interrupted time series analysis. The consumption of carbapenems, expressed in defined daily doses (DDD), was also assessed. As a secondary objective, the incidence of infections by carbapenem-resistant Klebsiella pneumoniae (CRKP) and the percentage of CRKP invasive isolates in the same time periods were compared. RESULTS: After the ASP intervention, the mean monthly percentage of inappropriate carbapenem prescriptions dropped from 59% to 25%, and the mean monthly proportion of carbapenem treated patients decreased from 3% to 1%. The interrupted time series analysis confirmed a significant decrease in the percentage of inappropriate carbapenem prescriptions (-41.6%, p = 0.0262) and in the proportion of carbapenem treated patients (-2.1%, p < 0.0001). Carbapenem consumption decreased from 5.2 to 1.6 DDD x 100 patient-days. The incidence of CRKP infections remained unchanged (29.1 × 100,000 patient-days vs 28.9 × 100,000 patient-days, p = 0.9864) and the percentage of CRKP invasive isolates decreased, though not significantly, from 36.4% to 13.3% (p = 0.3478). CONCLUSIONS: The implementation of a carbapenem-focused ASP was effective at limiting the inappropriate use of carbapenems and was associated with a significant decrease in carbapenem consumption. Such effects were sustained during a 24-month post-intervention period.

Yield and clinical impact of blood cultures in patients admitted to an internal medicine ward.

The purpose of this prospective observational study was to evaluate the yield and clinical impact of blood cultures in a 78-bed Internal Medicine ward of a medium-sized Italian acute care hospital. During a two-month study period, 154 (mean age: 75.2 ++ 12.2 years; 94 males) out of 620 (24.8%) hospitalized patients underwent 174 blood cultures and were enrolled in the study. The rate of true-positive cultures was 11.5% (20/174) and the rate of false-positive (contaminants) was 5.7% (10/174). A total of 23 microorganisms (5 multidrug resistant strains), most frequently Escherichia coli (n = 10), Klebsiella pneumoniae (n = 3) and Staphylococcus aureus (n = 3), were isolated. The positivity rate was significantly higher in patients with urinary tract infection (31%) and abdomen infection (26.1%) than in patients with pneumonia (4.9%; p<0.01). Although the positivity rate in patients exposed to antibiotics was lower than in those not exposed, the difference was not statistically significant. Therapy changes due to blood culture positivity were observed in 7.1% of the patients overall. In-hospital death was observed in nine of the 136 patients with negative blood cultures (6.6%) and in none of the 18 patients with positive blood cultures. These results indicate that the yield and clinical impact of blood cultures is quite low in patients admitted to an Internal Medicine ward and suggest the need to improve the adequacy of the indications to perform the test.

Investigation on silent bacterial infections in specimens from pregnant women affected by spontaneous miscarriage.

Miscarriage is one of the main complications occurring in pregnancy. The association between adverse pregnancy outcomes and silent bacterial infections has been poorly investigated. Ureaplasma parvum and urealiticum, Mycoplasma genitalium and hominis and Chlamydia trachomatis DNA sequences have been investigated by polymerase chain reaction (PCR) methods in chorionic villi tissues and peripheral blood mononuclear cells (PBMCs) from females with spontaneous abortion (SA, n = 100) and females who underwent voluntary interruption of pregnancy (VI, n = 100). U. parvum DNA was detected in 14% and 15% of SA and VI, respectively, with a mean of bacterial DNA load of 1.3 × 10-1 copy/cell in SA and 2.8 × 10 -3 copy/cell in VI; U. urealiticum DNA was detected in 3% and 2% of SA and VI specimens, respectively, with a mean DNA load of 3.3 × 10-3 copy/cell in SA and 1.6 × 10-3 copy/cell in VI; M. hominis DNA was detected in 5% of SA specimens with a DNA load of 1.3 × 10-4 copy/cell and in 6% of VI specimens with a DNA load of 1.4 × 10-4 copy/cell; C. trachomatis DNA was detected in 3% of SA specimens with a DNA load of 1.5 × 10-4 copy/cell and in 4% of VI specimens with a mean DNA load of 1.4 × 10-4 copy/cell. In PBMCs from the SA and VI groups, Ureaplasma spp, Mycoplasma spp and C. trachomatis DNAs were detected with a prevalence of 1%-3%. Bacteria were investigated, for the first time, by quantitative real-time PCR (qPCR) in chorionic villi tissues and PBMCs from women affected by SA and VI. These data may help to understand the role and our knowledge of the silent infections in SA.

Rare case of massive congenital bilateral chylothorax in a hydropic fetus with true mosaicism 47,XXX/46,XX.

Fetal congenital chylothorax is a rare condition that occurs sporadically or can be associated with abnormal karyotype or structural chromosomal anomalies. We report a unique case of fetal congenital bilateral chylothorax associated with mosaicism 47,XXX/46,XX. A female fetus affected by massive bilateral hydrothorax and ascites was diagnosed at 34(+1) weeks of gestation. Previous ultrasonographic exams were completely normal. Immune causes of hydrops were excluded. Elective cesarean section was performed soon after bilateral thoracocentesis. The analysis of drained pleural fluid revealed its lymphatic nature. The fetal karyotyping, performed on chorionic villi at the 11th week, had shown mosaicism 47,XXX/46,XX, later confirmed in the newborn's blood. We hypothesized that chylothorax may be part of the phenotypic spectrum of 47 XXX karyotype and we suggest an ultrasound follow-up of the fetus at closer intervals than the routine timing for this condition, even if it is not usually characterized by severe phenotypic features.

Marfan's syndrome and pregnancy: a good maternal and fetal outcome.

INTRODUCTION: this case report highlights the important role of a multidisciplinary team's task in the care of pregnant women with Marfan's syndrome (MFS), a systemic disorder of connective tissue that is transmitted as an autosomal dominant trait. CASE: a 42 year-old italian pregnant woman with Marfan's syndrome and degenerative heart disease (aneurysmatic dilatation of the aortic root, mitral regurgitation and prosthetic mitralic valve) was clinically assessed jointly by an obstetrician and a cardiologist, 'the obstetric team specialised in management of high risk pregnancy', every 2-3 weeks from the 21(th) week of gestation. The first ambulatory monitoring echocardiography revelead aneurysmatic dilatation of the aortic root (41 mm), good function of the previously replaced mitral valve, cardiac ejection fraction 51% and telediastolic volume 116 ml. The echocardiographies showed no changes up to 32 weeks gestation. At the 34(th) week of gestation she had a slight decrease in cardiac ejection fraction and minimal increase of left ventricular diastolic volume. Therefore she underwent elective cesarean section under general anesthesia at 35 weeks' gestation. The postpartum course was uneventfull for the patient and the baby. CONCLUSION: pregnant women with heart disease benefit from an appropriate antenatal management, which may result in a favourable outcome.