Daria Nicolosi

The tumor microenvironment in hepatocellular carcinoma (review).

The tumor microenvironment has been largely studied as a dynamic system orchestrated by inflammatory cells, including cancer cells, stroma as well as the extracellular matrix. It is useful to describe and predict the phenotypic characteristics of cancer. Furthermore, a better understanding of its interplay with the various aspects of the tumor cells may be utilized for the discovery of novel molecular targets. Liver cancer is considered a model of the relation occurring between the tumor micro-environment and tumor development. The chronic inflammatory status of the liver, sustained by the infection of hepatitis viruses, as well as the production of cytokines and growth factors within the parenchyma, lead to an intricate microenvironment. The identification of novel molecular therapeutic targets may improve the outcome of patients with liver cancer as it remains the third leading cause of cancer death worldwide. In the present study, the tumor microenvironment in hepatocellular carcinoma (HCC) was explored by a review of the literature. Studies on hepatitis virus infections and the consequent chronic inflammatory status were examined. In this context, immune-mediated and/or virus-related molecular mechanisms have been hypothesized as being responsible for liver cancer development. The interlink among HCC microenvironment components, comprising cellular elements, cytokines, growth factors and several proteins is also described together with the role of matrix metalloproteinases in HCC development. Finally, the rationale for targeting tumor-stromal interface is summarized in the context of new therapeutic opportunities.

In vitro activity of tigecycline and comparators against carbapenem-susceptible and resistant Acinetobacter baumannii clinical isolates in Italy

BackgroundIn a recent multi-centre Italian survey (2003–2004), conducted in 45 laboratories throughout Italy with the aim of monitoring microorganisms responsible for severe infections and their antibiotic resistance, Acinetobacter baumannii was isolated from various wards of 9 hospitals as one of the most frequent pathogens. One hundred and seven clinically significant strains of A. baumannii isolates were included in this study to determine the in vitro activity of tigecycline and comparator agents.MethodsTests for the susceptibility to antibiotics were performed by the broth microdilution method as recommended by CLSI guidelines. The following antibiotics were tested: aztreonam, piperacillin/tazobactam, ampicillin/sulbactam, ceftazidime, cefepime, imipenem, meropenem tetracycline, doxycycline, tigecycline, gentamicin, amikacin, ciprofloxacin, colistin, and trimethoprim/sulphametoxazole. The PCR assay was used to determine the presence of OXA, VIM, or IMP genes in the carbapenem resistant strains.ResultsA. baumannii showed widespread resistance to ceftazidime, ciprofloxacin and aztreonam in more than 90% of the strains; resistance to imipenem and meropenem was 50 and 59% respectively, amikacin and gentamicin were both active against about 30% of the strains and colistin about 99%, with only one strain resistant. By comparison with tetracyclines, tigecycline and doxycycline showed a higher activity. In particular, tigecycline showed a MIC90 value of 2 mg/L and our strains displayed a unimodal distribution of susceptibility being indistinctly active against carbapenem-susceptible and resistant strains, these latter possessed OXA-type variant enzymes.ConclusionIn conclusion, tigecycline had a good activity against the MDR A. baumannii strains while maintaining the same MIC90 of 2 mg/L against the carbapenem-resistant strains.

Bacterial isolates from severe infections and their antibiotic susceptibility patterns in Italy: a nationwide study in the hospital setting

Abstract The most frequent agents of severe bacterial infections and their antibiotic susceptibility patterns were determined in patients admitted to 45 Italian hospitals over the years 2002-2003. The most common diagnoses were: sepsis (33.8%), pneumonia (9.4%), intravascular catheter-associated infections (9.3%) and ventilator-associated pneumonia (8.1%). Overall, 5115 bacterial isolates were identified from 4228 patients. Three bacterial species, Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli accounted for more than 50% of the isolates. Other prevalent bacterial isolates were Staphylococcus epidermidis and Enterococcus faecalis, while Acinetobacter baumanii ranked third among all Intensive Care Unit (ICU) isolates. 7% of S. aureus had intermediate resistance to vancomycin. Although E. faecalis displayed no vancomycin resistance, 34% of vancomycin-resistant isolates were found among Enterococcus faecium, one of the highest rates found to date, emphasizing the difference between these two enterococcal species. All the Gram-positive pathogens were susceptible to linezolid, with the exception of approximately 2% of the enterococcal isolates that were intermediate with a minimum inhibitory concentration (MIC)=4 μg/ml. Almost 10% of Escherichia coli, 14% of Klebsiella pneumoniae, 22% of Serratia marcescens and 50% of Enterobacter cloacae were non-susceptible to cefotaxime. Amikacin was the most active antibiotic against P. aeruginosa that showed lack of susceptibility to ceftazidime, gentamicin, piperacillin and ciprofloxacin ranging from 20 to 35%. FinallyAcinetobacter baumanii showed a high level of resistance to all the antibiotics tested including imipenem (58%). The results obtained in this study, the first of its kind in Italy, offer indications for guiding empirical therapy and implementing specific interventions to fight antibiotic-resistant bacterial infections and their transmission in the hospital setting in Italy.

Heteroresistance to glycopeptides in Italian meticillin-resistant Staphylococcus aureus (MRSA) isolates

The prevalence and molecular characterisation of heteroresistant vancomycin-intermediate Staphylococcus aureus (hVISA) strains were determined in a large group of Italian strains isolated between 2005 and mid 2007. Amongst the 1284 strains isolated from documented infections in hospitalised patients (bloodstream infection, pneumonia, and skin and skin-structure infections), 139 S. aureus with vancomycin minimum inhibitory concentrations (MICs) between 1 mg/L and 2 mg/L were screened for the presence of hVISA using three different methods and were confirmed by population analysis profile (PAP). Thirty-six hVISA strains (25.9%) were detected. Amongst the three screening methods used, the macro Etest (MET) demonstrated 100% specificity and 75% sensitivity. hVISA strains were accessory gene regulator (agr) types I and II and belonged to the major nosocomial clones circulating in Italy (ST8, ST239, ST247 and ST228). All strains were susceptible to quinupristin/dalfopristin, linezolid, daptomycin, tigecycline and dalbavancin. In conclusion, we have demonstrated that hVISA isolates are common amongst MRSA isolates with MICs between 1 mg/L and 2 mg/L in Italy. MET, with its high sensitivity and specificity, should be used for early detection of hVISA, especially in patients with serious or prolonged infections sustained by MRSA. Finally, the most recent anti-Gram-positive drugs maintained their full spectrum of in vitro activity against these strains.

Intra-abdominal infections: etiology, epidemiology, microbiological diagnosis and antibiotic resistance.

Abstract Intra-abdominal infections (IAIs) are commonly encountered in clinical practice. The etiology of these infections, often polymicrobial in nature, can be variable and usually includes organisms derived from the gut microbiota. In community-acquired IAIs enterobacteria predominate (mostly Escherichia coli) in combination with anaerobes (mostly Bacteroides fragilis). In nosocomial IAIs, which can complicate abdominal surgery, other pathogens can also play a role, such as Pseudomonas aeruginosa, Acinetobacter baumannii, Staphylococcus aureus, Enterococcus spp. and Candida spp. Diagnostic microbiology of IAIs is complex and plays a relevant role, especially in some situations (e.g. presence of foreign bodies, potential presence of resistant or uncommon pathogens, nosocomial infections in subjects with risk factors). Antibiotic resistance issues are currently encountered in most pathogenic species causing IAIs. Resistance affects all major classes of antimicrobial agents, often involving multiple classes and resulting in complex resistance phenotypes for which only a very limited number of drugs remain active.

Nanotechnology approaches for antibacterial drug delivery: Preparation and microbiological evaluation of fusogenic liposomes carrying fusidic acid

Many antibacterial drugs have some difficulty passing through the bacterial cell membrane, especially if they have a high molecular weight or large spatial structure. Consequently, intrinsic resistance is shown by some bacterial strains. Reduced cell membrane permeability is one of the mechanisms of resistance known for fusidic acid (FUS), a bacteriostatic steroidal compound with activity limited to Gram-positive bacteria. Moreover, the lipophilic character of FUS has been shown to cause drug retention inside the bilayers of cell membranes, preventing its diffusion towards target sites inside the cytoplasm. Targeting antimicrobial agents by means of liposomes may be a valid strategy in the treatment of infections refractory to conventional routes of antimicrobial treatment. On this basis, loading of FUS in fusogenic liposomes (FLs) was planned in this study. Fusogenic small unilamellar vesicles loaded with FUS were produced to evaluate their influence on improving the cell penetration and antibacterial activity of the antibiotic. The produced carriers were technologically characterised and were subjected to an in vitro microbiological assay against several strains of Gram-negative and Gram-positive bacteria. The experimental results showed that encapsulating FUS in a liposomal carrier can improve antimicrobial efficacy and reduce the effective concentration required, probably through putative mechanisms of increased diffusion through the bacterial cell membrane. In fact, whilst free FUS was active only on the tested Gram-positive strains, incubation of FUS-loaded FLs exhibited growth inhibitory activity both against Gram-positive and Gram-negative strains. The lowest MICs were obtained against Staphylococcus epidermidis (≤0.15 μg/mL) and Acinetobacter baumannii (37.5 μg/mL) clinical strains.

Anti-Adhesion Activity of A2-type Proanthocyanidins (a Cranberry Major Component) on Uropathogenic E. coli and P. mirabilis Strains

Urinary tract infections (UTIs) are relatively common in women and may be classified as uncomplicated or complicated, depending upon the urinary tract anatomy and physiology. Acute uncomplicated cystitis (AUC) occurs when urinary pathogens from the bowel or vagina colonize the periurethral mucosa and reach the bladder. The vast majority of episodes in healthy women involving the same bacterial strain that caused the initial infection are thought to be reinfections. About 90% of AUC are caused by uropathogenic Escherichia coli (UPEC), but Proteus mirabilis also plays an important role. Several studies support the importance of cranberry (Vaccinium macrocarpon) proanthocyanidins in preventing adhesion of P-fimbriated UPEC to uroepithelial cells. In this study, we evaluated the in vitro anti-adhesion activity of A2-linked proanthocyanidins from cranberry on a UPEC and Proteus mirabilis strains and their possible influence on urease activity of the latter. A significant reduction of UPEC adhesion (up to 75%) on the HT1376 cell line was observed vs. control. For the strains of P. mirabilis there was also a reduction of adhesion (up to 75%) compared to controls, as well as a reduction in motility and urease activity. These results suggest that A2-type cranberry proanthocyanidins could aid in maintaining urinary tract health.

Antibiotic Susceptibility Profiles of Uncommon Bacterial Species Causing Severe Infections in Italy

Abstract This study presents the results of the italian “Severe infections project” involving bacteria that can be considered rare causes of disease. We isolated 30 uncommon human pathogens from a total of 60 strains (1.2% of all the isolates). The most frequent sources of uncommon human pathogens were primary bloodstream infections (48.3%) and pneumonia (20%). Species such as Comamonas testosteroni, Enterococcus hirae, Kluyvera ascorbata, Kluyvera cryocrescens, Leclercia adecarboxylata and Ochrobactrum anthropi were recovered from bacteremia patients. Clinically useful antimicrobial agents were tested against each isolate. Resistance to 4 or more antibiotics tested was found in Achromobacter xylosoxidans, O. anthropi, Pseudomonas stutzeri, Citrobacter braakii, Enterobacter sakazakii, K. ascorbata, Proteus penneri and Serratia plymuthica. About 16% of the Gram-negative species were resistant to third-generation cephalosporins and 28.6% of the staphylococci were oxacillin-resistant. The results from this study offer indications for empirical therapy for severe infections from uncommon human pathogens.

A tailored health surveillance program unveils a case of MALT lymphoma in an HCV-positive health-care worker

Non-Hodgkin lymphoma (NHL) may occur among hepatitis C virus (HCV)-infected individuals. HCV is one of the most common blood-borne pathogens transmitted from patients to health-care workers (HCWs). The development of NHL among HCV-infected HCWs has recently been shown. To investigate this issue further a tailored health surveillance program was applied to 3,138 HCWs from four Medical Institutions. To this aim, all employees were screened for both anti-HCV antibodies and HCV-related extrahepatic manifestations. The HCV prevalence rate, similar among all the HCW subgroups, was 7.3%. The occurrence of a gastric mucosa-associated lymphoma tissue (MALT) lymphoma, diagnosed in a physician following a long history of HCV chronic infection, was observed. Molecular characterization of MALT tissue indicated that immunoglobuline gene combinations were those usually found among HCV-associated lymphomas. Furthermore, B-cell expansion exhibited t(14;18) translocation, as a genetic abnormality associated with the development of MALT lymphomas from HCV-positive patients. Overall, these findings support the hypothesis that HCV viral infection potentially affects the pathway of transformation and progression of lymphoma cells. The occurrence of B-cell NHL, among HCV-positive HCWs, is an additional reason to apply the standard precautions to reduce the risk of blood-borne pathogen transmission.

Comparison of Systemic Flurithromycin Therapy and Clinical Procedures in the Treatment of Periodontal Diseases

Abstract The purpose of the present investigation was to evaluate, in 20 periodontal patients, the microbial and clinical effects of flurithromycin therapy plus scaling and root planning (SRP) in comparison with SRP alone. Clinical assessments of plaque, bleeding on probing and pocket depth were made prior to SRP alone and SRP plus flurithromycin therapy (375 mg twice daily for 5 days) and after both treatments. Subgingival plaque samples (n. 180) were taken prior to and after both treatments and analyzed by conventional bacteriological procedures. Differences in pocket depth and prevalence of bacterial species were analyzed pre- and post-therapies using statistical analyses. A significant decrease (p<0.001) was seen for pocket depth post SRP alone and post SRP plus flurithromycin. After two treatments, Actinobacillus actinomycetemcomitans, Bacteroides forsythus and Prevotella melaninogenica were eradicated from all tested sites. If we compare the preva-lence of the species isolated after SRP alone and after SRP plus flurithromycin sta-tistically significant differences were detected for P. gingivalis and for Fusobacterium nucleatum (p<0.05 and p<0.01, respectively). Flurithromycin can be considered a useful adjunct to mechanical periodontal treatment since it is more efficient in eliminating periodontal pathogens.