FTIR, ESI-MS, VT-NMR and SANS study of trehalose thermal stabilization of lysozyme.

Protein aggregation is often associated with conformational and structural changes of secondary structure elements that may lead to exposure of some specific residues. Data obtained in our experimental work indicate that trehalose (1.0M) effectively prevent thermal inactivation and aggregation of lysozyme. In fact, following heat treatment, lysozyme generates insoluble aggregates which are almost completely absent in the samples incubated in the presence of the disaccharide. The experimental approach consists in studying FTIR spectra of intrinsic chromophores and VT-NMR measurements on lysozyme water mixtures in the presence of trehalose. FTIR measurements suggest that in the presence of 1.0 M of trehalose there is a clear decrease in the loss of α-helix structure and in the formation of intermolecularly aggregated structures. Electrospray ionization mass spectrometry (ESI-MS) was employed to characterize protein structural transition, highlighting as trehalose remarkably influenced solvent accessibility to the amide peptide backbone upon heat treatment, consequentially decreasing local protein environment changes. Complementary informations are also obtained by UV-vis spectroscopy measurements, Congo Red binding and activity determinations.

[A case of community-acquired MRSA (CA-MRSA) sepsis complicated by meningoencephalitis and cerebral abscess, successfully treated with linezolid]. / Un caso di sespi da MRSA comunitario (CA-MRSA) complicata da meningoencefalite ed ascesso cerebrale trattato con successo con linezolid.

The authors describe a clinical case regarding a young female patient affected by sepsis due to methicillin-resistant Staphylococcus aureus (MRSA), associated to meningoencephalitis and cerebral abscess. The patient had no contact with hospitals in the months prior to illness and had always been healthy. She recovered thanks to linezolid therapy. The MRSA strain proved positive for Panton-Valentine leukocidin (PVL positive) and was therefore defined as community-acquired MRSA (CA-MRSA).

Surgical site infections in HIV-infected patients: results from an Italian prospective multicenter observational study.

BACKGROUND: The quality of life of the HIV-infected population in developed countries has substantially improved over the years. Accordingly, the clinical limitations in the surgical treatment of the HIV-infected patients are becoming fewer, and the number of HIV-infected patients undergoing surgical interventions of all types is increasing. However, available data on the incidence and risk factors for post-surgical complications, such as surgical site infections (SSI), in HIV-infected patients are still limited and often controversial. The aim of this study was to determine the incidence and the associated risk factors for SSI in HIV-infected patients. METHODS: A 1-year observational prospective multicenter surveillance study was conducted in 11 Italian Infectious Diseases Clinical Centers from which 305 consecutive HIV-infected patients undergoing different surgical procedures were enrolled. Postdischarge surveillance was conducted within 30 days after surgery. A number of variables were included in a multivariate analysis aimed at assessing potential risk factors for SSI, including body mass index, diabetes, Hepatitis C (HCV) and hepatitis B virus infection, lipodistrophy, HIV viral load, CD4 cell count and white blood cell count, preoperative hospital stay, National Nosocomial Infection Surveillance (NNIS) risk score, and any antimicrobial prophylaxis. RESULTS: SSI occurred in 29 of 305 (9.5%) patients, of which 17 (58.6%) SSI occurred during hospital stay, and 12 (41.4%) occurred during the postdischarge period. The SSI of the 29 patients were classified as superficial (21, 72.4%), deep (four, 13.8%), organ/space (one, 3.4%), and sepsis (three, 10.3%). Nearly 50% of the superficial and 50% of the deep SSI occurred during the postdischarge period. Organ/space infection and sepsis accounted for 13.7% of all SSI and were observed during the in-hospital stay. The multivariate analysis revealed that HCV co-infection was significantly associated to SSI occurrence. Total hospital stay was longer among patients with SSI than among those without SSI (p = 0.041). CONCLUSION: Although 92.5% of our HIV-infected patients presented a NNIS score < or = 1, the SSI rate was twofold higher than that reported in Italian and European studies for the general population, with more severe clinical presentations. This is the first report of an association between HCV-HIV co-infection and SSI occurrence. Additionally, the viro-immunological status of our patients was not related to SSI occurrence, which suggests the need for further research for other potential risk factors that may be implicated in the occurrence of SSI.

[Prevention of nosocomial infections: surveillance based on microbiological data]. / Effetti del monitoraggio sistematico sulla prevenzione delle infezioni ospedaliere: la sorveglianza basata sui dati del laboratorio di microbiologia.

BACKGROUND: In the C. Poma Hospital of Mantua we have been using a system of continuous surveillance of nosocomial infections based on microbiological data for the past 4 years. This monitoring estimates the incidence of the microorganisms found in cultures, especially those at risk of causing nosocomial infections. MATERIALS AND METHODS: Since June 2001 microbiological data have been registered using the Mercurio-Dianoema software and elaborated by means of Microsoft Excel in order to obtain information about isolated bacteria, especially those resistant to antibiotics. RESULTS: Surveillance in "critical" wards revealed the presence of Pseudomonas aeruginosa, Staphylococcus aureus and Candida albicans in the intensive care unit in the period 2003-2005. The most frequent bacteria in hemodialysis have been coagulase-negative Staphylococci and Staphylococcus aureus, with variable methicillin resistance. CONCLUSION: The analysis of microbiological data has promoted effective measures to reduce the incidence of these bacteria (increased rules of good practice, hand washing, etc.). If nosocomial infections or high-risk microorganisms occur, assessments are carried out; monitoring of the antibiotic resistance of the bacteria is very important.

[Epidemiologic surveillance of multi-drug resistant Pseudomonas aeruginosa in Mantova Hospital (Italy)]. / Sorveglianza epidemiologica di Pseudomonas aeruginosa multiresistente nell'Ospedale di Mantova.

For the period 2002-2005 we verified and compared the data of the prevalence and resistance of Pseudomonas aeruginosa (PA) isolated in Mantova Hospital (Italy) with the data from the international database. From the first six-month period of 2004 a significant increase was found (9% vs 28.8%) in the prevalence of multi-drug resistant PA (MDR-PA). The principal wards involved were the Intensive Care Unit and the Department of Respiratory Diseases. A significant increase in resistance rates was observed for all antimicrobials tested, in particular for aztreonam, ceftazidime, ciprofloxacin, gentamycin and imipenem. The lowest dual resistance rates were observed between amikacina with piperacillin/tazobactam, while the highest were for those that included ciprofloxacin and beta-lactams (aztreonam, cefepime). In this study we confirm the importance of continuous surveillance of laboratory data and tightening local control measures for nosocomial infections in order to prevent the spread and selection of MDR-PA.

[Infection risk and personal protective devices]. / Rischio infettivo e dispositivi di protezione individuale.

The Aa discuss the evidence and recommendations for the use of personal protective equipment by health care practitioners in general care settings; the use of aprons, gowns, gloves, eye protections, face masks is valutated on the basis of an assessment of the risk of transmission of microrganisms to the patient or from the patient to health care practitioners. The primary uses of personal protective equipment are to protect staff and reduce opportunities for transmission of microrganisms in hospitals. A trend to eliminate the unnecessary wearing of aprons, gowns and masks in general care settings has evolved over the past twenty years due to the absence of evidence that they are effective.

Multiresistant Stenotrophomonas maltophilia tunneled CVC-related sepsis, treated with systemic and lock therapy.

In the last decade, a remarkable increase in the incidence of nosocomial Gram-negative infections has been observed. These pathogens represent a substantial problem in clinical practice, due to the high resistance profile of most commonly used antibiotics. This phenomenon is surely a co-factor that exposes these susceptible patients to infections caused by selected pathogens like multiresistant Gram-negative rods. A typical example is represented by VAP (ventilator-associated pneumonia) sustained by Acinetobacter spp., Pseudomonas aeruginosa, Bulkolderia cepacia. The Authors describe a case of a central venous cather (CVC)-related Stenotrophomonas maltophilia sepsis in a patient affected by solid tumor, successfully treated with systemic antibiotic therapy associated with "lock therapy". This combination was able to cure the infection, allowing the patient to continue chemotherapy and saving the in situ CVC. The surveillance of CVCs, good adherence to the protocols and guidelines and "good practice" are the cornerstones for the prevention of nosocomial infections.

Antibiotic lock-technique for the treatment of catheter-related bloodstream infections.

The management of central venous catheter-related bloodstream infections (CRBSI), though still debated, requires the removal of the line in most cases: we investigated the efficacy of an alternative approach, based on higher concentrations of antibiotics locked within the catheter lumen, in an open, pilot study aimed at preserving the line in place and at eradicating the infection. Thirty consecutive patients carrying a central line over 10 days and who fulfilled criteria for ascertained diagnosis of bacterial CRBSI, had the catheter "locked" with antimicrobials therein; all patients also received systemic antibiotic therapy within the first 48 hours. Subsequently, 15 patients underwent locks alone, and 15 locks plus systemic therapy. Twenty-eight out of 30 (93.3%) patients retained the catheter in place, appearing to be cleared of infection and no treatment-related untoward events were observed. Locks should be considered as effective as line removal in the management of bacterial CRBSI in unselected patients, and could thus provide advantages in terms of resource sparing and lowered antibiotic pressure in the hospital setting.

Postnatal development of intestinal villi in the rat. Determination of villus size gradient.

The existence of the so called "Villus Size Gradient" (VSG) which defines the proportional decrease in height of intestinal villi from duodenum to ileum is well documented in adult animals and man. The aim of this study is to define whether the VSG is present since birth or, if not, when and why it appears. We have measured the height of intestinal villi in 25 rats: 5 at 1 day from birth, 5 at 5 days, 5 at 8 days, 5 at 15 days and 5 at 30 days. We have prepared histological slides of a duodenal, jejunal and ileal tract of each animal and measured the height of villi on microphotographs. At day 1 we observed a higher size of duodenal villi statistically significant with respect to jejunum and ileum, while at day 5 no differences were observed between the various intestinal tracts. The VSG become evident 8 days after birth progressively increasing to day 30. The predominance of duodenum present at birth is therefore probably due to the fetal developmental growth which is known to be more precocious in duodenum than in more distal tracts. Five days after birth the intestinal villi are equally developed, while in later ages the VSG appears. So we can conclude that the VSG is a consequence of luminal and humoral factors and not a predetermined event.