A new point-of-care test for the rapid antimicrobial susceptibility assessment of uropathogens.

Bacterial resistance to antimicrobials is considered a major issue worldwide. This condition may account for treatment failure of urinary tract infections, which are among the most common infections both in community and healthcare settings. Therapy against uropathogens is generally administered empirically, possibly leading to unsuccessful therapy, recurrence and development of antibiotic resistance. The reduction in analytical time to obtain antimicrobial susceptibility test (AST) results could play a key role in reducing the cost of healthcare, providing information about antibiotic efficacy and thus preventing from either exploiting new and expensive antibiotics unnecessarily or using obsolete and ineffective ones. A more rational choice among treatment options would hence lead to more effective treatment and faster resolution. In this paper we evaluated the performance of a new Point Of Care Test (POCT) for the rapid prediction of antimicrobial susceptibility in urine samples performed without the need of a laboratory or specialized technicians. 349 patients were enrolled in two open-label, monocentric, non-interventional clinical trials in partnership with an Emergency Medicine ward and the Day Hospital of two large healthcare facilities in Rome. Antibiogram was carried out on 97 patients. Results from analysis of urine samples with the POCT were compared with those from routine AST performed on culture-positive samples, displaying high accuracy (>90%) for all tested antimicrobial drugs and yielding reliable results in less than 12 hours from urine collection thus reducing analytical and management costs

Severe Acute Respiratory Syndrome Coronavirus Elicits a Weak Interferon Response Compared to Traditional Interferon-Inducing Viruses

The aim of the present study is to investigate changes of interferon (IFN) production occurring over the first 48 h after infection of peripheral blood mononuclear cells (PBMCs) with severe acute respiratory syndrome (SARS) coronavirus (CoV) and to compare these changes to those induced by well-established IFN-inducing viruses, such as vesicular stomatitis (VSV) and Newcastle viruses (NDV). Experiments have been carried out using PBMCs of 10 different healthy donors. The results showed that the antiviral activity of IFN contained in the supernatant of SARS-CoV-infected PBMCs was lower than those induced by VSV and NDV. Consequently, SARS-CoV induces a lower synthesis of IFN-alpha, -beta and -gamma compared to VSV and NDV. Characterization of the profile of IFN-alpha subtypes genes expression in SARS-CoV-infected PBMCs demonstrated that the level of IFN-alpha 2 and -6 subtypes were higher compared to other IFN-alpha subtypes namely, IFN-alpha 5, -8, -10, -13/1, -17, and -21. In conclusion, SARS-CoV induces IFNs to a less extent compared to VSV and NDV, thus suggesting that the IFN system does play a limited role in early host defense against SARS-CoV infection. Copyright (C) 2008 S. Karger AG, Base

Effect of Acid Adaptation on the Fate of Listeria monocytogenes in THP-1 Human Macrophages Activated by Gamma Interferon

In Listeria monocytogenes the acid tolerance response (ATR) takes place through a programmed molecular response which ensures cell survival under unfavorable conditions. Much evidence links ATR with virulence, but the molecular determinants involved in the reactivity to low pHs and the behavior of acid-exposed bacteria within host cells are still poorly understood. We have investigated the effect of acid adaptation on the fate of L. monocytogenes in human macrophages. Expression of genes encoding determinants for cell invasion and intracellular survival was tested for acid-exposed bacteria, and invasive behavior in the human myelomonocytic cell line THP-1 activated with gamma interferon was assessed. Functional approaches demonstrated that preexposure to an acidic pH enhances the survival of L. monocytogenes in activated human macrophages and that this effect is associated with an altered pattern of expression of genes involved in acid resistance and cell invasion. Significantly decreased transcription of the plcA gene, encoding a phospholipase C involved in vacuolar escape and cell-to-cell spread, was observed in acid-adapted bacteria. This effect was due to a reduction in the quantity of the bicistronic plcA-prfA transcript, concomitant with an increase in the level(s) of the monocistronic prfA mRNA(s). The transcriptional shift from distal to proximal prfA promoters resulted in equal levels of the prfA transcript (and, as a consequence, of the inlA, hly, and actA transcripts) under neutral and acidic conditions. In contrast, the sodC and gad genes, encoding a cytoplasmic superoxide dismutase and the glutamate-based acid resistance system, respectively, were positively regulated at a low pH. Morphological approaches confirmed the increased intracellular survival and growth of acid-adapted L. monocytogenes cells both in vacuoles and in the cytoplasm of interferon gamma-activated THP-1 macrophages. Our data indicate that preexposure to a low pH has a positive impact on subsequent challenge of L. monocytogenes with macrophagic cells

A new point-of-care test for the rapid detection of urinary tract infections

Urinary tract infections (UTIs) are among the most common infections in all age groups. Fast and accurate diagnosis is essential to ensure a timely and effective therapy. Alongside with reference culture-based methods, several point-of-care tests (POCTs) for early detection of UTIs have been developed, but they have not been significantly implemented in current clinical practice. The Micro Biological Survey (MBS) POCT is a simple test developed by MBS Diagnostics Ltd. (London, UK) for the detection and management of UTIs. The present study has been undertaken to investigate the potentials and limits of the MBS POCT. A total of 349 patients were enrolled in two open-label, monocentric, non-interventional clinical trials in collaboration with an Emergency Medicine department and the outpatient clinic of two hospitals in Rome. Results of urine analysis using the MBS POCT were compared with those of the routine culture-based tests for UTI diagnosis performed by the hospital laboratory. The MBS POCT provided fast results revealing high bacterial count UTIs (≥ 105 CFU/ml) with 97% accuracy, 92% sensitivity, 100% specificity, 99% PPV, and 96% NPV within a 5-h analytical time threshold

Specific mutations in the C-terminus domain of HBV surface antigen significantly correlate with low level of serum HBV-DNA in patients with chronic HBV infection

Background: To define HBsAg-mutations correlated with different serum HBV-DNA levels in HBV chronically-infected drug-naive patients. Methods: This study included 187 patients stratified into the following ranges of serum HBV-DNA: 12-2000 IU/ml, 2000-100,000 IU/ml, and > 100,000 IU/ml. HBsAg-mutations were associated with HBV-DNA levels by applying a Bayesian-Partitional-Model and Fisher-exact test. Mutant and wild-type HBV genotype-D genomes were expressed in Huh7 cells and HBsAg-production was determined in cell-supernatants at 3 days-post-transfection. Results: Specific HBsAg-mutations (M197T,-S204N-Y206C/H-F220L) were significantly correlated with serum HBV-DNA 90%, P <0.05). The presence of Y206C/H and/or F220L was also associated with lower median (IQR) HBsAg-levels and lower median (IQR) transaminases (for HBsAg: 250[115-840] IU/ml for Y206C/H and/or F220L versus 4300[640-11,838] IU/ml for wild-type, P = 0.023; for ALT:28[21-40] IU/ml versus 53[34-90] IU/ml, P <0.001). These mutations were localized in the HBsAg C-terminus, known to be involved in virion and/or HBsAg secretion. The co-occurrence of Y206C + F220L was found significant by cluster-analysis, (P = 0.02). In addition, in an in-vitro model Y206C + F220L determined a 2.8-3.3 fold-reduction of HBsAg-amount released in supernatants compared to single mutants and wt (Y206C + F220L = 5,679 IU/ml; Y206H = 16,305 IU/ml; F220L = 18,368 IU/ml; Y206C = 18,680 IU/ml; wt = 14,280 IU/ml, P <0.05). Conclusions: Specific HBsAg-mutations (compartmentalized in the HBsAg C-terminus) correlated with low-serum HBV-DNA and HBsAg-levels. These findings can be important to understand mechanisms underlying low HBV replicative potential including the inactive-carrier state. (C) 2014 The British Infection Association. Published by Elsevier Ltd. All rights reserve

Anti-HBV treatment induces novel reverse transcriptase mutations with reflective effect on HBV S antigen

Introduction: The identification of novel reverse-transcriptase (RT) drug-resistance mutations is critical in predicting the probability of success to anti-HBV treatment. Furthermore, due to HBV-RT/HBsAg gene-overlap, they can have an impact on HBsAg-detection and quantification. Methods: 356 full-length HBV-RT sequences from 197 drug-naive patients and 159 patients experiencing virological-breakthrough to nucleoside/nucleotide-analogs (NUCs) were analyzed. Mutants and wild-type HBs-antigens were expressed in HuH7-hepatocytes and quantified in cell-supernatants and cell-lysates by Architect HBsAg-assay. Results: Ten novel RT-mutations (rtN53T-rtS78T-rtS85F-rtS135T-rtA181I-rtA200V-rtK212Q-rtL229V/F-rtM309K) correlated with specific NUC-treatments and classical drug-resistance mutations on divergent evolutionary pathways. Some of them reduced RT-binding affinity for anti-HBV drugs and altered S-antigen structure. Indeed, rtS78T (prevalence: 1.1% in drug-naive and 12.2% in adefovir-failing patients) decreased the RT-affinity for adefovir more than the classical adefovir-resistance mutations rtA181 T/V (WT: -9.63 kcal/mol, rtA181T: -9.30 kcal/mol, rtA181V: -7.96 kcal/mol, rtS78T: -7.37 kcal/mol). Moreover, rtS78T introduced a stop-codon at HBsAg-position 69, and completely abrogated HBsAg-quantification in both supernatants and cell-lysates, indicating an impaired HBsAg-secretion/production. Furthermore, the HBsAg-mutation sP217L, silent in RT, significantly correlated with M204V/I-related virological-breakthrough and increased HBsAg-quantification in cell-lysate. Conclusions: Mutations beyond those classically known can affect drug-binding affinity of mutated HBV-RT, and may have potential effects on HBsAg. Their cumulative effect on resistance and HBV-pathogenicity indicates the importance of preventing therapeutic failures. (C) 2013 The British Infection Association. Published by Elsevier Ltd. All rights reserved

Role of hepatitis B virus genetic barrier in drug-resistance and immune-escape development

BACKGROUND: Impact of hepatitis B virus genetic barrier, defined as the number and type of nucleotide substitutions required to overcome drug/immune selective pressure, on drug-resistance/immune-escape development is unknown. METHODS: Genetic barrier was calculated according to Van de Vijver (2006) in 3482 hepatitis B virus-reverse transcriptase/HBV surface antigen sequences from 555 drug-naïve patients and 2927 antiviral-treated patients infected with hepatitis B virus genotypes A-G. RESULTS: Despite high natural variability, genetic barrier for drug-resistance development is identical amongst hepatitis B virus genotypes, but varies according to drug-resistance mutation type. Highest genetic barrier is found for secondary/compensatory mutations (e.g. rtL80I/V-rtL180M-rtV173L), whilst most primary mutations (including rtM204V-rtA181T/V-rtI169T-rtA194T) are associated with low genetic barrier. An exception is rtM204I, which can derive from a transition or a transversion. Genotypes A and G are more prone to develop immune/diagnostic-escape mutations sT114R and sG130N. Vaccine-escape associated sT131N-mutation is a natural polymorphism in both A and G genotypes. CONCLUSION: Genetic barrier and reverse transcriptase/HBV surface antigen overlapping can synergistically influence hepatitis B virus drug-resistance/immune-escape development. The different immune-escape potential of specific hepatitis B virus genotypes could have important clinical consequences in terms of disease progression, vaccine strategies and correct HBV surface antigen detection