Analysis of Routine and Integrative Data from Clostridioides difficile Infection Diagnosis and the Consequent Observations

Abstract: Background: Clostridioides difficile Infection (CDI) is an acute disease that needs a fast proper treatment. Unfortunately, the diagnosis, and above all the understanding of the results, remain arduous. Objective: This study analyzed routine and integrative results of all fecal samples from patients over time. Our aim was to understand the dynamics of CDI infection and the meaning of \u201cdifficult to interpret\u201d results, to make physicians better understand the various tools they can use. Methods: We evaluated routine results obtained from 815 diarrheal stools with Enzyme Immunoassay (EIA) that detects C. difficile Glutamate Dehydrogenase (GDH) antigen and toxin B. We also reanalyzed a part of samples using integrative tests: a Real-time polymerase chain reaction (RT-PCR) for C. difficile toxin B gene (tcdB) and the automated immunoassay VIDAS C. difficile system for GDH and toxins A/B. Results: EIA GDH positivity increased through multiple testing over time, with a P value <0.001, depicting a sort of bacterial growth curve. Eighty-five percent of GDH positive/toxin B negative, i.e., discrepant, samples PCR were tcdB positive, 61.5% of discrepant tcdB positive samples were VIDAS toxins A/B positive, and 44.4% of GDH EIA negative stools were VIDAS GDH positive. Conclusion: The results confirmed the low sensitivity of the EIA system for C. difficile GDH and toxins, questioned the use of the latter for concluding any CDI diagnostic algorithm, and led us to indicate the algorithm beginning with tcdB molecular research, and continuing in positive cases with VIDAS CD GDH method, as the most effective for CDI

Pathogenic potential of Escherichia coli from polymicrobial urinary tract infections.

none1G. PIATTIPiatti, Gabriell

The inhibitory co-receptors: a way to save from anergy the HIV-specific T cells.

The functional impairment of HIV-specific CD4(+) T cells during chronic HIV infection is thought to be closely linked to viral replication and to T cell exhaustion. T cell exhaustion in the presence of ongoing antigen exposure is a common feature of chronic viral infection, in which dysfunctional T cells fail to eliminate the virus. Otherwise, antiviral T cell function impairment is a poorly understood mechanism. Increasing evidences show that HIV-specific T lymphocytes up-regulated inducible co-receptors, such as the Cytoxic T Lymphocyte Antigen-4, (CTLA-4, or CD152) and Programmed Death-1 (PD-1) and that blockade of the CD152 or PD-1 pathway restores HIV-specific CD4(+) T cell function in HIV infection. This review will focus on finding a possible role for inhibitory receptors on virus-specific CD4(+) T cells. The analysis of the role of CD152 and PD-1 in HIV-1 infection could provide important insight into the mechanism of viral induced immune dysfunction and lead to immunotherapeutic strategies to reverse immune suppression in this pathology

Virulence Factors in Urinary Escherichia coli Strains: Phylogenetic Background and Quinolone and Fluoroquinolone Resistance▿

Quinolone- and fluoroquinolone-resistant Escherichia coli strains harbor fewer virulence factors than susceptible strains. The reasons underlying this correlation are incompletely understood. We investigated the phylogenetic background, the presence of the papC, hlyA, and cnf1 (pathogenicity island IIJ96-associated), fimA, iss, and iutA genes, and the presence of type 1 fimbriae, P fimbriae, and hemolysin in 243 urinary E. coli isolates resistant only to quinolones (8%), resistant to both quinolones and fluoroquinolones (51%), or susceptible to both drugs (41%). Group B2 accounted for 56% of the isolates, showing a significantly higher prevalence among fluoroquinolone-susceptible strains than among resistant strains (65% versus 50% [P = 0.03]). hly and cnf1 were significantly more associated with susceptibility (P < 0.001) and with group B2 (P < 0.001 for group B2 versus groups A and D). However, within group B2, fluoroquinolone-resistant strains showed lower prevalences of papC, hlyA, and cnf1 than their susceptible counterparts (P < 0.001). In contrast, the incidence of iutA appeared higher for refractory isolates, including group B2, than for susceptible isolates (P < 0.001). Only in group B2 did fluoroquinolone-resistant strains reveal a lesser ability to agglutinate Saccharomyces cerevisiae (7%) than quinolone-resistant (87%) and susceptible (80%) isolates, despite uniform possession of fimA genes. No similar contrast emerged for expression of hemolysin and P fimbriae. Mutations conferring quinolone and fluoroquinolone resistance may thus require a particular genetic background, not strictly correlated with phylogenetic groups. More interestingly, the mutational event itself can affect the expression of type 1 fimbriae, at least in the prevalent and complex B2 strains

A Highly Efficient Polystyrene-Based Cationic Resin to Reduce Bacterial Contaminations in Water

Nowadays, new water disinfection materials attract a lot of attention for their cost-saving and ease of application. Nevertheless, the poor durability of the matrices and the loss of physically incorporated or chemically attached antibacterial agents that can occur during water purification processes considerably limit their prolonged use. In this study, a polystyrene-based cationic resin (R4) with intrinsic broad-spectrum antibacterial effects was produced without needing to be enriched with additional antibacterial agents that could detach during use. Particularly, R4 was achieved by copolymerizing 4-ammonium-butyl-styrene (4-ABSTY) with N,N-dimethylacrylamide (DMAA) and using N-(2-acryloylamino-ethyl)-acrylamide (AAEA) as a cross-linker. The R4 obtained showed a spherical morphology, micro-dimensioned particles, high hydrophilicity, high-level porosity, and excellent swelling capabilities. Additionally, the swollen R4 to its maximum swelling capability, when dried with gentle heating for 3 h, released water following the Higuchi’s kinetics, thus returning to the original structure. In time–kill experiments on the clinical isolates of multidrug-resistant (MDR) pathogens of fecal origin, such as enterococci, Group B Salmonella species, and Escherichia coli, R4 showed rapid bactericidal effects on enterococci and Salmonella, and reduced E. coli viable cells by 99.8% after 4 h. When aqueous samples artificially infected by a mixture of the same bacteria of fecal origin were exposed for different times to R4 in a column, simulating a water purification system, 4 h of contact was sufficient for R4 to show the best bacterial killing efficiency of 99%. Overall, thanks to its physicochemical properties, killing efficiency, low costs of production, and scalability, R4 could become a cost-effective material for building systems to effectively reduce bacterial, even polymicrobial, water contamination

Synthesis, Characterization, and Bactericidal Activity of a 4-Ammoniumbuthylstyrene-Based Random Copolymer

The growing resistance of bacteria to current chemotherapy is a global concern that urgently requires new and effective antimicrobial agents, aimed at curing untreatable infection, reducing unacceptable healthcare costs and human mortality. Cationic polymers, that mimic antimicrobial cationic peptides, represent promising broad-spectrum agents, being less susceptible to develop resistance than low molecular weight antibiotics. We, thus, designed, and herein report, the synthesis and physicochemical characterization of a water-soluble cationic copolymer (P5), obtained by copolymerizing the laboratory-made monomer 4-ammoniumbuthylstyrene hydrochloride with di-methyl-acrylamide as uncharged diluent. The antibacterial activity of P5 was assessed against several multi-drug-resistant clinical isolates of both Gram-positive and Gram-negative species. Except for strains characterized by modifications of the membrane charge, most of the tested isolates were sensible to the new molecule. P5 showed remarkable antibacterial activity against several isolates of genera Enterococcus, Staphylococcus, Pseudomonas, Klebsiella, and against Escherichia coli, Acinetobacter baumannii and Stenotrophomonas maltophilia, displaying a minimum MIC value of 3.15 \ub5M. In time-killing and turbidimetric studies, P5 displayed a rapid non-lytic bactericidal activity. Due to its water-solubility and wide bactericidal spectrum, P5 could represent a promising novel agent capable of overcoming severe infections sustained by bacteria resistant the presently available antibiotics

Catheter-Related Sepsis by Candida pararugosa in an Adult Patient under Chemotherapy Regimen

Candida pararugosa is present in animals and humans in different organs and biological liquids, usually as a saprophyte. We report the case of a 61-year-old woman diagnosed with de novo stage IV metastatic lobular breast cancer, carrying a central venous catheter (port-a-cath) and bilateral stents for perirenal infiltration by malignancy. During chemotherapy regimen, a febrile episode occurred, along with a high level of serum glucan. The port-a-cath was removed after blood collection for culture, which gave isolation of Candida pararugosa strains. Given high glucan level and the patient's frailty, empirical treatment with fluconazole was started with load-dose, 800 mg orally, at day 1 and, afterwards, with 400 mg daily for two weeks. The phenotype of susceptibility to antibiotics of the strain demonstrated lower minimal inhibitory concentration to fluconazole than that reported in the literature. The patient remained asymptomatic, and inflammation parameters showed normalization. Unfortunately, three weeks later, meningeal localization of cancer caused rapid deterioration and death

Identification of Salmonella enterica Serovar Typhi DNA Fragments with Transcriptional Activity Under Different Growth Conditions.

Abstract: Salmonella enterica serovar Typhi is a human pathogenic microorganism with a very complex infective cycle, involving the transit of bacteria across different microenvironments; to optimize the performance of attenuated Salmonella strains suitable as live carriers of heterologous antigens, fine tuning of wild type bacteria gene expression is essential. Several DNA fragments were obtained from a Salmonella enterica serovar Typhi (vi+, fim+) blood isolate and 18 clones were selected according to the dimension of the insert (range <0.2-1.6 kb). These fragments showed a transcriptional activity in a promoterless vector cloned in Escherichia coli background, according to homogeneous parameters. The results obtained provide an insight about signals mediating gene activation in vivo, particularly in the microenvironments known to exist during the infectious process, even if the fragments are not promoters sequences. Finally, the functional characterization of several fragments showed that they possessed an efficient and homogeneous transcriptional activity, worth to be further investigated