IFN-I inducible miR-3614-5p targets ADAR1 isoforms and fine tunes innate immune activation

Regulation of innate immune responses is essential for maintenance of immune homeostasis and development of an appropriate immunity against microbial infection. We show here that miR-3614-5p, product of the TRIM25 host gene, is induced by type I interferon (IFN-I) in several human non-immune and immune cell types, in particular in primary myeloid cells. Studies in HeLa cells showed that miR-3614-5p represses both p110 and p150 ADAR1 and reduces constitutive and IFN-induced A-to-I RNA editing. In line with this, activation of innate sensors and expression of IFN-β and the pro-inflammatory IL-6 are promoted. MiR-3614-5p directly targets ADAR1 transcripts by binding to one specific site in the 3’UTR. Moreover, we could show that endogenous miR-3614-5p is associated with Ago2 and targets ADAR1 in IFN-stimulated cells. Overall, we propose that, by reducing ADAR1, IFN-I-induced miR-3614-5p contributes to lowering the activation threshold of innate sensors. Our findings provide new insights into the role of miR-3614-5p, placing it as a potential fine tuner of dsRNA metabolism, cell homeostasis and innate immunity.

Interlaboratory evaluation of Mucorales PCR assays for testing serum specimens: A study by the fungal PCR Initiative and the Modimucor study group

Interlaboratory evaluations of Mucorales qPCR assays were developed to assess the reproducibility and performance of methods currently used. The participants comprised 12 laboratories from French university hospitals (nine of them participating in the Modimucor study) and 11 laboratories participating in the Fungal PCR Initiative. For panel 1, three sera were each spiked with DNA from three different species (Rhizomucor pusillus, Lichtheimia corymbifera, Rhizopus oryzae). For panel 2, six sera with three concentrations of R. pusillus and L. corymbifera (1, 10, and 100 genomes/ml) were prepared. Each panel included a blind negative-control serum. A form was distributed with each panel to collect results and required technical information, including DNA extraction method, sample volume used, DNA elution volume, qPCR method, qPCR template input volume, qPCR total reaction volume, qPCR platform, and qPCR reagents used. For panel 1, assessing 18 different protocols, qualitative results (positive or negative) were correct in 97% of cases (70/72). A very low interlaboratory variability in Cq values (SD = 1.89 cycles) were observed. For panel 2 assessing 26 different protocols, the detection rates were high (77-100%) for 5/6 of spiked serum. There was a significant association between the qPCR platform and performance. However, certain technical steps and optimal combinations of factors may also impact performance. The good reproducibility and performance demonstrated in this study support the use of Mucorales qPCR as part of the diagnostic strategy for mucormycosis.

Mortality from COVID-19

Abstract

The differences of the epidemiology (incidence, case-to-death rate, mortality, etc) of COVID-19 between USA and Italy are analyzed taking into account the social, economic and sanitary characteristics of the two countries, both severely hit be the pandemic; and the causes of the so many different behaviors of the disease in each of them are discussed and explained.

Assessment of the Role of 1,3-β-d-Glucan Testing for the Diagnosis of Invasive Fungal Infections in Adults

Detection of 1,3-β-d-glucan (BDG) in serum has been evaluated for its inclusion as a mycological criterion of invasive fungal infections (IFI) according to EORTC and Mycoses Study Group (MSG) definitions. BDG testing may be useful for the diagnosis of both invasive aspergillosis and invasive candidiasis, when interpreted in conjunction with other clinical/radiological signs and microbiological markers of IFI. However, its performance and utility vary according to patient population (hematologic cancer patients, solid-organ transplant recipients, intensive care unit patients) and pretest likelihood of IFI. The objectives of this article are to provide a systematic review of the performance of BDG testing and to assess recommendations for its use and interpretation in different clinical settings.

Genome-Wide Gene Expression Analysis of Mtb-Infected DC Highlights the Rapamycin-Driven Modulation of Regulatory Cytokines via the mTOR/GSK-3β Axis

In human primary dendritic cells (DC) rapamycin-an autophagy inducer and protein synthesis inhibitor-overcomes the autophagy block induced by Mycobacterium tuberculosis (Mtb) and promotes a Th1 response via IL-12 secretion. Here, the immunostimulatory activity of rapamycin in Mtb-infected DC was further investigated by analyzing both transcriptome and translatome gene profiles. Hundreds of differentially expressed genes (DEGs) were identified by transcriptome and translatome analyses of Mtb-infected DC, and some of these genes were found further modulated by rapamycin. The majority of transcriptome-associated DEGs overlapped with those present in the translatome, suggesting that transcriptionally stimulated mRNAs are also actively translated. In silico analysis of DEGs revealed significant changes in intracellular cascades related to cytokine production, cytokine-induced signaling and immune response to pathogens. In particular, rapamycin treatment of Mtb-infected DC caused an enrichment of IFN-β, IFN-λ and IFN-stimulated gene transcripts in the polysome-associated RNA fraction. In addition, rapamycin led to an increase of IL-12, IL-23, IL-1β, IL-6, and TNF-α but to a reduction of IL-10. Interestingly, upon silencing or pharmacological inhibition of GSK-3β, the rapamycin-driven modulation of the pro- and anti-inflammatory cytokine balance was lost, indicating that, in Mtb-infected DC, GSK-3β acts as molecular switch for the regulation of the cytokine milieu. In conclusion, our study sheds light on the molecular mechanism by which autophagy induction contributes to DC activation during Mtb infection and points to rapamycin and GSK-3β modulators as promising compounds for host-directed therapy in the control of Mtb infection.

The impact of anti-mould prophylaxis on Aspergillus PCR blood testing for the diagnosis of invasive aspergillosis

BACKGROUND

The performance of the galactomannan enzyme immunoassay (GM-EIA) is impaired in patients receiving mould-active antifungal therapy. The impact of mould-active antifungal therapy on Aspergillus PCR testing needs to be determined.

OBJECTIVES

To determine the influence of anti-mould prophylaxis (AMP) on the performance of PCR blood testing to aid the diagnosis of proven/probable invasive aspergillosis (IA).

METHODS

As part of the systematic review and meta-analysis of 22 cohort studies investigating Aspergillus PCR blood testing in 2912 patients at risk of IA, subgroup analysis was performed to determine the impact of AMP on the accuracy of Aspergillus PCR. The incidence of IA was calculated in patients receiving and not receiving AMP. The impact of two different positivity thresholds (requiring either a single PCR positive test result or ≥2 consecutive PCR positive test results) on accuracy was evaluated. Meta-analytical pooling of sensitivity and specificity was performed by logistic mixed-model regression.

RESULTS

In total, 1661 (57%) patients received prophylaxis. The incidence of IA was 14.2%, significantly lower in the prophylaxis group (11%-12%) compared with the non-prophylaxis group (18%-19%) (P < 0.001). The use of AMP did not affect sensitivity, but significantly decreased specificity [single PCR positive result threshold: 26% reduction (P = 0.005); ≥2 consecutive PCR positive results threshold: 12% reduction (P = 0.019)].

CONCLUSIONS

Contrary to its influence on GM-EIA, AMP significantly decreases Aspergillus PCR specificity, without affecting sensitivity, possibly as a consequence of AMP limiting the clinical progression of IA and/or leading to false-negative GM-EIA results, preventing the classification of probable IA using the EORTC/MSGERC definitions.

Human Ubiquitin-Specific Peptidase 18 Is Regulated by microRNAs via the 3'Untranslated Region, A Sequence Duplicated in Long Intergenic Non-coding RNA Genes Residing in chr22q11.21

Ubiquitin-specific peptidase 18 (USP18) acts as gatekeeper of type I interferon (IFN) responses by binding to the IFN receptor subunit IFNAR2 and preventing activation of the downstream JAK/STAT pathway. In any given cell type, the level of USP18 is a key determinant of the output of IFN-stimulated transcripts. How the baseline level of USP18 is finely tuned in different cell types remains ill defined. Here, we identified microRNAs (miRNAs) that efficiently target USP18 through binding to the 3’untranslated region (3’UTR). Among these, three miRNAs are particularly enriched in circulating monocytes which exhibit low baseline USP18. Intriguingly, the USP18 3’UTR sequence is duplicated in human and chimpanzee genomes. In humans, four USP18 3’UTR copies were previously found to be embedded in long intergenic non-coding (linc) RNA genes residing in chr22q11.21 and known as FAM247A-D. Here, we further characterized their sequence and measured their expression profile in human tissues. Importantly, we describe an additional lincRNA bearing USP18 3’UTR (here linc-UR-B1) that is expressed only in testis. RNA-seq data analyses from testicular cell subsets revealed a positive correlation between linc-UR-B1 and USP18 expression in spermatocytes and spermatids. Overall, our findings uncover a set of miRNAs and lincRNAs, which may be part of a network evolved to fine-tune baseline USP18, particularly in cell types where IFN responsiveness needs to be tightly controlled.

Differential Responses of Human Dendritic Cells to Live or Inactivated Staphylococcus aureus: Impact on Cytokine Production and T Helper Expansion

Understanding Staphylococcus aureus (S. aureus)-host immune system interaction is crucial to meet the tremendous medical need associated with this life-threatening bacterial infection. Given the crucial role of dendritic cells (DC) in dictating immune responses upon microbial challenge, we investigated how the bacterial viability and the conservation of structural integrity influence the response of human DC to S. aureus. To this end, human primary DC were stimulated with the methicillin-resistant S. aureus USA300 live strain, USA300 inactivated by heat (HI), ultraviolet irradiation (UVI), or paraformaldehyde treatment (PFAI) and subsequently analyzed for cell phenotype and immune-modulatory properties. Although no differences in terms of DC viability and maturation were observed when DC were stimulated with live or inactivated bacteria, the production of IL-12, IL-23, and other cytokines differed significantly. The Th1 and Th17 expansion was also more pronounced in response to live vs. inactivated S. aureus. Interestingly, cytokine production in DC treated with live and inactivated USA300 required phagocytosis, whereas blocking endosomal Toll-like receptor signaling mainly reduced the cytokine release by live and HI USA300. A further analysis of IFN-β signaling revealed the induction of a cyclic GMP-AMP synthase stimulator of interferon genes (cGAS-STING)-independent and IRF3-dependent signaling pathway(s) in UVI-stimulated DC. This study underscores the capacity of human DC to discriminate between live and inactivated S. aureus and, further, indicates that DC may represent a valuable experimental setting to test different inactivation methods with regard to the retention of S. aureus immunoregulatory properties. These and further insights may be useful for the development of novel therapeutic and prophylactic anti-S. aureus vaccine strategies.

A cell type-specific transcriptomic approach to map B cell and monocyte type I interferon-linked pathogenic signatures in Multiple Sclerosis

Alteration in endogenous Interferon (IFN) system may profoundly impact immune cell function in autoimmune diseases. Here, we provide evidence that dysregulation in IFN-regulated genes and pathways are involved in B cell- and monocyte-driven pathogenic contribution to Multiple Sclerosis (MS) development and maintenance. In particular, by using an Interferome-based cell type-specific approach, we characterized an increased susceptibility to an IFN-linked caspase-3 dependent apoptotic cell death in both B cells and monocytes of MS patients that may arise from their chronic activation and persistent stimulation by activated T cells. Ongoing caspase-3 activation functionally impacts on MS monocyte properties influencing the STAT-3/IL-16 axis, thus, driving increased expression and massive release of the bio-active IL-16 triggering and perpetuating CD4⁺ T cell migration. Importantly, our analysis also identified a previously unknown multi-component defect in type I IFN-mediated signaling and response to virus pathways specific of MS B cells, impacting on induction of anti-viral responses and Epstein-barr virus infection control in patients. Taking advantage of cell type-specific transcriptomics and in-depth functional validation, this study revealed pathogenic contribution of endogenous IFN signaling and IFN-regulated cell processes to MS pathogenesis with implications on fate and functions of B cells and monocytes that may hold therapeutic potential.

Thymosins in multiple sclerosis and its experimental models: moving from basic to clinical application

BACKGROUND

Multiple sclerosis (MS) afflicts more than 2.5 million individuals worldwide and this number is increasing over time. Within the past years, a great number of disease-modifying treatments have emerged; however, efficacious treatments and a cure for MS await discovery. Thymosins, soluble hormone-like peptides produced by the thymus gland, can mediate immune and non-immune physiological processes and have gained interest in recent years as therapeutics in inflammatory and autoimmune diseases.

METHODS

Pubmed was searched with no time constraints for articles using a combination of the keywords "thymosin/s" or "thymus factor/s" AND "multiple sclerosis", mesh terms with no language restriction.

RESULTS

Here, we review the state-of-the-art on the effects of thymosins on MS and its experimental models. In particular, we describe what is known in this field on the roles of thymosin-α1 (Tα1) and -β4 (Tβ4) as potential anti-inflammatory as well as neuroprotective and remyelinating molecules and their mechanisms of action.

CONCLUSION

Based on the data that Tα1 and Tβ4 act as anti-inflammatory molecules and as inducers of myelin repair and neuronal protection, respectively, a possible therapeutic application in MS for Tα1 and Tβ4 alone or combined with other approved drugs may be envisaged. This approach is reasonable in light of the current clinical usage of Tα1 and data demonstrating the safety, tolerability and efficacy of Tβ4 in clinical practice.

Mycobacterium tuberculosis-induced miR-155 subverts autophagy by targeting ATG3 in human dendritic cells

Autophagy is a primordial eukaryotic pathway, which provides the immune system with multiple mechanisms for the elimination of invading pathogens including Mycobacterium tuberculosis (Mtb). As a consequence, Mtb has evolved different strategies to hijack the autophagy process. Given the crucial role of human primary dendritic cells (DC) in host immunity control, we characterized Mtb-DC interplay by studying the contribution of cellular microRNAs (miRNAs) in the post-transcriptional regulation of autophagy related genes. From the expression profile of de-regulated miRNAs obtained in Mtb-infected human DC, we identified 7 miRNAs whose expression was previously found to be altered in specimens of TB patients. Among them, gene ontology analysis showed that miR-155, miR-155* and miR-146a target mRNAs with a significant enrichment in biological processes linked to autophagy. Interestingly, miR-155 was significantly stimulated by live and virulent Mtb and enriched in polysome-associated RNA fraction, where actively translated mRNAs reside. The putative pair interaction among the E2 conjugating enzyme involved in LC3-lipidation and autophagosome formation-ATG3-and miR-155 arose by target prediction analysis, was confirmed by both luciferase reporter assay and Atg3 immunoblotting analysis of miR-155-transfected DC, which showed also a consistent Atg3 protein and LC3 lipidated form reduction. Late in infection, when miR-155 expression peaked, both the level of Atg3 and the number of LC3 puncta per cell (autophagosomes) decreased dramatically. In accordance, miR-155 silencing rescued autophagosome number in Mtb infected DC and enhanced autolysosome fusion, thereby supporting a previously unidentified role of the miR-155 as inhibitor of ATG3 expression. Taken together, our findings suggest how Mtb can manipulate cellular miRNA expression to regulate Atg3 for its own survival, and highlight the importance to develop novel therapeutic strategies against tuberculosis that would boost autophagy.

Mycobacterium tuberculosis (Mtb) is one of the most successful pathogens in human history and remains the second leading cause of death from an infectious agent worldwide. The major reason of Mtb success relies on its ability to evade host immunity. Autophagy, a cellular mechanism involved in intracellular pathogen elimination, is one of the pathways hijacked by Mtb to elude the control of dendritic cells (DC), major cellular effectors of immune response. Recently, it has become clear that Mtb infection not only alters cellular gene expression, but also controls the level of small RNA molecules, namely microRNAs (miRNAs), which function as negative regulators of mRNA translation into protein. In the present study, we observed that the infection of human DC with Mtb leads to a strong induction of host miR-155, a critical regulator of host immune response. By mean of miR-155 induction, Mtb reduces Atg3 protein content, a crucial enzyme needed for the initial phase of the autophagic process. Interestingly, miR-155 silencing during Mtb infection restores Atg3 level and rescues autophagy. These findings contribute to better elucidate Mtb-triggered escape mechanisms and highlight the importance to develop host-directed therapies to combat tuberculosis based on autophagy boosting.

Staphylococcus aureus Esx Factors Control Human Dendritic Cell Functions Conditioning Th1/Th17 Response

The opportunistic pathogen Staphylococcus aureus (S. aureus) is a major cause of nosocomial- and community-acquired infections. In addition, many antibiotic-resistant strains are emerging worldwide, thus, there is an urgent unmet need to pinpoint novel therapeutic and prophylactic strategies. In the present study, we characterized the impact of infection with the pandemic methicillin-resistant USA300 S. aureus strain on human primary dendritic cells (DC), key initiators and regulators of immune responses. In particular, among staphylococcal virulence factors, the function of EsxA and EsxB, two small acidic dimeric proteins secreted by the type VII-like secretion system Ess (ESAT-6-like secretion system), was investigated in human DC setting. A comparative analysis of bacterial entry, replication rate as well as DC maturation, apoptosis, signaling pathway activation and cytokine production was performed by using wild type (wt) USA300 and three isogenic mutants carrying the deletion of esxA (ΔesxA), esxB (ΔesxB), or both genes (ΔesxAB). The S. aureus mutant lacking only the EsxA protein (ΔesxA) stimulated a stronger pro-apoptotic phenotype in infected DC as compared to wt USA300, ΔesxAB, and ΔesxB strains. When the mutant carrying the esxB deletion (ΔesxB) was analyzed, a higher production of both regulatory and pro-inflammatory mediators was found in the infected DC with respect to those challenged with the wt counterpart and the other esx mutants. In accordance with these data, supernatant derived from ΔesxB-infected DC promoted a stronger release of both IFN-γ and IL-17 from CD4⁺ T cells as compared with those conditioned with supernatants derived from wild type USA300-, ΔesxAB-, and ΔesxA-infected cultures. Although, the interaction of S. aureus with human DC is not yet fully understood, our data suggest that both cytokine production and apoptotic process are modulated by Esx factors, thus indicating a possible role of these proteins in the modulation of DC-mediated immunity to S. aureus.

Thymosin-α1 expands deficient IL-10-producing regulatory B cell subsets in relapsing–remitting multiple sclerosis patients

Background:

B cells are key pathogenic effectors in multiple sclerosis (MS) and several therapies have been designed to restrain B cell abnormalities by directly targeting this lymphocyte population.

Objectives:

Moving from our data showing a Toll-like receptor (TLR)7-driven dysregulation of B cell response in relapsing–remitting multiple sclerosis (RRMS) and having found a low serum level of Thymosin-α1 (Tα1) in patients, we investigated whether the addition of this molecule to peripheral blood mononuclear cells (PBMCs) would influence the expansion of regulatory B cell subsets, known to dampen autoimmune inflammation.

Methods:

Serum Tα1 level was measured by enzyme immunoassay. Cytokine expression was evaluated by Cytometric Bead Array (CBA), enzyme-linked immunosorbent assay (ELISA), and real-time reverse transcription polymerase chain reaction (RT-PCR). B cell subsets were analyzed by flow cytometry.

Results:

Tα1 pre-treatment induces an anti-inflammatory status in TLR7-stimulated RRMS PBMC cultures, reducing the secretion of pro-inflammatory interleukin (IL)-6, IL-8, and IL-1β while significantly increasing the regulatory IL-10 and IL-35. Indeed, Tα1 treatment enhanced expansion of CD19+CD24+CD38hi transitional-immature and CD24low/negCD38hi plasmablast-like regulatory B cell subsets, which likely inhibit both interferon (IFN)-γ and IL-17 production.

Conclusion::

Our study reveals a deficient ability of B cells from MS patients to differentiate into regulatory subsets and unveils a novel anti-inflammatory and repurposing potential for Tα1 in MS targeting B cell response.

Worldwide Epidemiology and Antibiotic Resistance of Staphylococcus aureus

Staphylococcus aureus is an important human pathogen, responsible for infections in the community and the healthcare setting. Although much of the attention is focused on the methicillin-resistant "variant" MRSA, the methicillin-susceptible counterpart (MSSA) remains a prime species in infections. The epidemiology of S. aureus, especially of MRSA, showed a rapid evolution in the last years. After representing a typical nosocomial multidrug-resistant pathogen, MRSA has recently emerged in the community and among farmed animals thanks to its ability to evolve and adapt to different settings. Global surveillance has shown that MRSA represents a problem in all continents and countries where studies have been carried out, determining an increase in mortality and the need to use last-resource expensive antibiotics. S. aureus can easily acquire resistance to antibiotics and MRSA is characteristically multidrug resistant. Resistance to vancomycin, the principal anti-MRSA antibiotic is rare, although isolates with decreased susceptibility are recovered in many areas. Resistance to the more recently introduced antibiotics, linezolid and daptomycin, has emerged; however, they remain substantially active against the large majority of MSSA and MRSA. Newer antistaphylococcal drugs have been developed, but since their clinical use has been very limited so far, little is known about the emergence of resistance. Molecular typing techniques have allowed to identify the major successful clones and lineages of MSSA and MRSA, including high-risk clones, and to trace their diffusion. In the face of a continuously evolving scenario, this review depicts the most common clones circulating in different geographical areas and in different settings at present. Since the evolution of S. aureus will continue, it is important to maintain the attention on the epidemiology of S. aureus in the future with a global view.

Dual effect of Thymosin α 1 on human monocyte-derived dendritic cell in vitro stimulated with viral and bacterial toll-like receptor agonists

OBJECTIVES

Thymosin α 1 (Tα1) recently gained interest as immune adjuvant for vaccines because of its ability to modulate the T-cell/dendritic cell (DC) axis and to improve antibody production. The objective of this study was to determine whether Tα1 would address in vitro the response of human primary monocyte-derived DC, crucial regulators of vaccine-induced immunity, upon exposure to different toll-like receptor (TLR) agonists or infection with viruses or bacteria.

METHODS

DC maturation and production of pro-inflammatory cytokines were analyzed.

RESULTS

Our data revealed a dual effect of Tα1 on DC biology upon viral or bacterial stimulation. Interestingly, Tα1 enhanced human leukocyte antigen (HLA)-I and II surface expression and secretion of IL-6, TNF-α and IL-8 when DCs were treated with viral TLR3 and TLR7/8 agonists. Similarly, in pandemic H1N1 influenza A-infected DCs, Tα1 raised the expression of maturation markers and type I and III Interferon (IFN). In contrast, following bacterial TLR2 and 4 stimulation, as well as upon Bacillus Calmette-Guerin infection, the presence of Tα1 in DC cultures drastically lowered the analyzed cellular parameters.

CONCLUSION

The knowledge that Tα1 pleiotropic effect might ameliorate anti-viral immune responses and, at the same time, dampen inflammation caused by bacterial infections could lay the groundwork for a more appropriate therapeutic application of this molecule.

Effects on bleeding complications of pharmacogenetic testing for initial dosing of vitamin K antagonists: a systematic review and meta-analysis

BACKGROUND

Although warfarin and other vitamin K antagonists (VKAs) are the most widely used oral anticoagulants for the prevention and treatment of thromboembolic events, a number of factors hamper their manageability, the most important being the inter-individual variability of the therapeutic dose requirement. Following the discovery of the influence of CYP2C9 and VKORC1 polymorphisms on VKA dose requirements, there has been interest in genotype-guided VKA dosing in order to reduce the risk of over-anticoagulation at the time of therapy initiation and hence the risk of bleeding, particularly prominent during the early days of treatment. To assess the impact on clinical outcomes of pharmacogenetic testing for initial VKA dosing, we have performed a systematic review and meta-analysis of the literature.

METHODS

MEDLINE, EMBASE and Cochrane databases were searched up to March 2014. Only randomized controlled trials comparing genotype-guided vs. clinically-guided warfarin dosing were included.

RESULTS

Nine trials including 2812 patients met the inclusion criteria and were pooled for meta-analytical evaluation. Risk of bias, assessed according to the Cochrane methodology, showed a low risk for the majority of domains analyzed in the included trials. A statistically significant reduction in the risk ratio (RR) for developing major bleeding events was observed in the pharmacogenetic-guided group compared with the control group (RR = 0.47; 95% CI, 0.23-0.96; P = 0.040).

CONCLUSIONS

The results of this meta-analysis show that genotype-guided initial VKA dosing is able to reduce serious bleeding events by approximately 50% compared with clinically-guided dosing approaches.

Meta-analyses of diagnostic tests in infectious diseases: how helpful are they in the intensive care setting?

In acute-care settings timely and accurate diagnostic tools are critical for patient treatment decisions and outcomes. This review provides an up-to-date look at the meta-analyses of diagnostic test for infections in the ICU setting. There have been 3 meta-analyses investigating the value of procalcitonin as diagnostic marker of sepsis: overall, the performance of procalcitonin test was found moderate-good. Two meta-analyses evaluated methods for diagnosing intravascular device-related bloodstream infections. In general, quantitative catheter segment culture and paired quantitative blood culture showed reliable diagnostic yield, though significant heterogeneity was observed among studies. Criteria of diagnosing VAP in the intensive care unit has been evaluated in 3 systematic reviews. Overall, the cumulative results cast doubts about the usefulness of bacteriological data and quantitative cultures in the diagnosis of VAP; moreover, 2 of these meta-analyses concluded that invasive strategies for VAP diagnosis do not affect mortality.

Antimicrobial use and resistance among Gram-negative bacilli in an Italian intensive care unit (ICU)

Gram-negative bacilli antimicrobial resistance remains a significant problem for patients in the intensive care unit (ICU). We performed a retrospective analysis of microbiological data and antibiotic consumption over a 4-year period (2000-2003) in an Italian ICU. Pseudomonas aeruginosa and Klebsiella pneumoniae represented approximately 40% of all isolates. The most significant trend in antimicrobial use was an increase in use of 3(rd )generation cephalosporins, imipenem, and ciprofloxacin. A significant trend toward an increase in resistance rates to piperacillin, 3( rd )generation cephalosporins and ciprofloxacin was observed for K. pneumoniae and a positive correlation between resistance and drug-usage was evident for K. pneumoniae and piperacillin, cefotaxime, ceftazidime, cefepime, and ciprofloxacin, but not for piperacillin/tazobactam. No statistically significant correlations were evidenced for P. aeruginosa. Trends in resistances were studied also for Serratia spp and Proteus spp. Isolation rates of extended-spectrum beta-lactamase (ESBL)-producing strains in pathogens studied were high, especially for K. pneumoniae (72%, 160/222) and Proteus spp (41%, 18/43). In conclusion, the study showed high resistance among Gram-negative organisms isolated in the ICU and significant ESBL production. A significant correlation between antibiotic consumption and increasing resistance was evident for K. pneumoniae.

Penetration of didanosine in semen of HIV-1-infected men

OBJECTIVES

The disposition of antiretroviral agents into genital tissue and fluids is one of the factors implicated in the control of viral replication within the male genital tract and should be an objective of highly active antiretroviral therapy. We have investigated didanosine penetration in seminal plasma of 16 HIV-infected patients.

PATIENTS AND METHODS

A total of 16 patients on didanosine (200 mg every 12 h or 400 mg once daily) participated in the pharmacokinetic study. After the didanosine morning dose, peripheral blood plasma and semen plasma were collected within the intervals 0-4, 4-8 and 8-12 h in the twice-daily regimen and 0-4, 4-12 and 12-24 h in the once-daily regimen.

RESULTS

Within each sampling time interval didanosine concentrations in seminal plasma were higher than in blood. The interquartile range of concentrations in seminal plasma was 292-1217 ng/mL, compared with 50-150 ng/mL in blood plasma. Didanosine could be detected in 14 of the 16 semen samples analysed and in 8 of the 16 blood samples.

CONCLUSIONS

We have demonstrated that didanosine penetrates into the seminal plasma in higher concentrations than in blood plasma.

Meta-analysis of BACTEC MGIT 960 and BACTEC 460 TB, with or without solid media, for detection of mycobacteria

In a meta-analysis of 10 studies, the BACTEC 960/MGIT and BACTEC 460 systems showed a sensitivity and specificity in detecting mycobacteria (1,381 strains from 14,745 clinical specimens) of 81.5 and 99.6% and 85.8 and 99.9%, respectively. Combined with solid media, the sensitivity of the two systems increased to 87.7 and 89.7%, respectively.

Pharmacokinetics and pharmacodynamics of nelfinavir administered twice or thrice daily to human immunodeficiency virus type 1-infected children

We studied the pharmacokinetics and pharmacodynamics of nelfinavir administered 2 or 3 times per day to human immunodeficiency virus type 1 (HIV-1)-infected children receiving highly active antiretroviral therapy containing nelfinavir. The geometric mean trough concentrations of nelfinavir for the thrice- and twice-daily regimens were 1.55 mg/L and 1.11 mg/L, respectively (P=not significant). Nelfinavir concentrations did not correlate with total daily dose, dose per kilogram of weight, age, weight, previous protease inhibitor (PI) experience, or CD4(+) cell percentage. In the 25 PI-naive children, the virus load reductions at 24 weeks of treatment with the twice- and thrice-daily regimens were comparable. A significantly higher percentage of children in the twice-daily group had a trough concentration of nelfinavir of less than the inhibitory concentration of 95% (P=.042). The decrease in the virus load at 24 weeks of treatment was not correlated with the trough concentration of nelfinavir. The variability of trough concentrations was extremely high, particularly among recipients of the twice-daily regimen, resulting in a higher number of patients with subinhibitory concentrations of nelfinavir in this group.

Use of the E test to assess synergy of antibiotic combinations against isolates of Burkholderia cepacia-complex from patients with cystic fibrosis

Treatment of Burkholderia cepacia-complex infections in cystic fibrosis patients is problematic, since the microorganism is often resistant to most antimicrobial agents. In this study, the Epsilometer test, or E test, was used to assess the activity of antimicrobial combinations against Burkholderia cepacia-complex. In a preliminary evaluation, the E test was compared to the checkerboard method using 10 test organisms. Synergy testing by the E test was then performed on 131 clinical isolates of Burkholderia cepacia-complex using various combinations of antimicrobial agents. Agreement between the E test and the checkerboard method was 90%. The rate of resistance to individual agents ranged from 48% for meropenem to 100% for tobramycin, chloramphenicol, and rifampin. In 71.6%, 15.6%, and 12.6% of the test evaluations performed, the combinations tested resulted in additivity/indifference, synergism, and antagonism, respectively. The highest rates of synergy were observed with combinations of ciprofloxacin-piperacillin (44%), rifampin-ceftazidime (33%), chloramphenicol-ceftazidime (22%), cotrimoxazole-piperacillin/tazobactam (22%), and ciprofloxacin-ceftazidime (21%). Rates of antagonism for cotrimoxazole and chloramphenicol in combination with beta-lactam agents were higher than those observed for ciprofloxacin plus beta-lactam agents. These results suggest that the E test is a valuable and practical method to be considered for improving the identification of possible therapeutic options in cystic fibrosis patients infected with organisms belonging to the Burkholderia cepacia-complex.

Meta-analysis of diagnostic procedures for Pneumocystis carinii pneumonia in HIV-1-infected patients

Sputum induction is a simple and noninvasive procedure for Pneumocystis carinii pneumonia (PCP) diagnosis in human immunodeficiency virus-1-positive patients, although less sensitive than bronchoalveolar lavage (BAL). In order to obtain an overview of the diagnostic accuracy of sputum induction, a systematic review and meta-analysis of studies reporting the comparative sensitivity and specificity of BAL (the "gold standard") and sputum induction was performed. The odds ratio and related 95% confidence interval were calculated using summary receiving operating characteristic curves as well as fixed-effect and random-effect models. Based on pooled data, the negative and positive predictive values were calculated for a range of PCP prevalence using a Bayesian approach. Seven prospective studies assessed the comparative accuracy of BAL and sputum induction. On the whole, sputum induction demonstrated 55.5% sensitivity and 98.6% specificity. The sensitivity of sputum induction was significantly higher with immunofluorescence than with cytochemical staining (67.1 versus 43.1%). In settings of 25-60% prevalence of PCP, the positive and negative predictive values ranged 86-96.7 and 66.2-89.8, respectively, with immunofluorescence, and 79-94.4 and 53-83.5% with cytochemical staining. In conclusion, in a setting of low prevalence of Pneumocystis carinii pneumonia, sputum induction, particularly with immunostaining, appears to be adequate for clinical decision-making.

The impact of human immunodeficiency virus type 1 on infectiousness of tuberculosis: a meta-analysis

To assess if the relative infectiousness of patients with tuberculosis is enhanced by coinfection with human immunodeficiency virus type 1 (HIV-1), data from 6 studies of 1240 health care workers who had contact with tuberculosis patients were analyzed. Overall rates of tuberculin skin test conversion were similar regardless of HIV-1 positivity of tuberculosis patients (odds ratio [OR], 1.04; 95% confidence interval [CI], 0.23-1.84). However, when only 3 studies during nosocomial outbreaks of multidrug-resistant Mycobacterium tuberculosis were analyzed, rates of skin test conversion were higher among contacts of HIV-1-positive index cases (OR, 2.85; 95% CI, 1.85-3.85; P=.0002). A second meta-analysis included data from 11 studies of 10,714 household contacts of tuberculosis patients. Prevalence of both skin test positivity (OR, 0.45; 95% CI, 0.20-1.03) and active disease (OR, 1.17; 95% CI, 0.78-1.56) were similar regardless of HIV-1 positivity of index cases. These data suggest that tuberculosis patients with HIV-1 infection are not intrinsically more infectious to their contacts than are HIV-1-negative tuberculosis patients.

Linezolid treatment of prosthetic hip Infections due to methicillin-resistant Staphylococcus aureus (MRSA)

Prosthetic joint infection is an infrequent but serious complication of total joint arthroplasty. Complete removal of all foreign material is essential, however when prosthesis removal is not possible or contraindicated, suppressive antibiotic therapy with retention of the functioning hip arthroplasty may be considered. Linezolid, the first approved oxazolidinone, appears to be a promising new agent for the treatment of serious Gram-positive infections. We report two cases of Methicillin-resistant Staphylococcus aureus (MRSA) prosthetic hip infections successfully treated with a long course of linezolid. This observation suggest that linezolid is a promising drug for the treatment of prosthetic joint infections due to MRSA or other Gram-positive pathogens, particularly when other therapeutic approaches are not feasible or a long-term antibiotic therapy is required.

Antibacterial prophylaxis

Bacterial infections remain an important cause of morbidity and mortality in neutropenic patients. A number of prophylactic strategies have been used in order to reduce the risk of infection during severe granulocytopenia. The measures that have been investigated include isolation of the patient, granulocyte transfusion, active or passive immunisation, acceleration of granulocyte recovery and prophylactic use of antibacterial agents. However, many of these approaches have fallen out of favour, mostly because of concerns about the long lasting efficacy. This paper focuses on the available prophylactic strategies, with emphasis on the use of antibacterial agents.

Use of antibiotics in an Italian children's hospital, 1993-1995; clinical and economic considerations

Antibiotic consumption and expenditure was studied during 1993 and 1995 in G. Gaslini children's hospital, an Italian 400-bed paediatric hospital, to see if any changes in use had occurred. There was an increase in the cost of antibacterial agents from 1993 to 1995, with a decrease in the daily cost of antibiotics and in the consumption of antiviral, antifungal and antiparasitic agents. There was a notable increase in the use of glycopeptides and carbapenems between 1995 and 1993 especially in specialities such as onco-haematology and intensive care. We suggest a basis for an antibiotic management programme aimed at reducing costs while still providing a high standard of care for patients.

Erythromycin resistance in Streptococcus pyogenes in Italy

In a prospective study of acute pharyngitis in Italian children, 69 (38.3%) of 180 isolates of Streptococcus pyogenes were resistant to macrolides. S. pyogenes was eradicated in 12 (63.1%) of 19 patients with erythromycin-resistant S. pyogenes treated with clarithromycin and in 22 (88%) of 25 patients with erythromycin-susceptible strains. The constitutive-resistant phenotype was correlated with failure of macrolide treatment.

The relationship between ritonavir plasma levels and side-effects: implications for therapeutic drug monitoring

OBJECTIVES

To assess whether the neurological or gastrointestinal adverse effects of ritonavir correlate with parameters of ritonavir systemic exposure.

METHODS

Peak (Cmax) and trough (Cmin) ritonavir plasma levels were compared in 11 patients experiencing side-effects (group A) versus 10 patients without side-effects (group B). Ritonavir was administered with the following escalation dosing scheme: 300, 400, 500 mg twice a day for 3, 4, and 5 days, respectively, then the full dose of 600 mg twice a day. Blood sampling was done in group A within 24 h of the occurrence of side-effects and in group B after at least 3 days of the full dosage regimen.

RESULTS

Both Cmax and Cmax were significantly higher (Mann-Whitney U test) in patients with side-effects. Cmax was [median (interquartile range)] 26.7 (22.7-33.3) mg/l versus 16.2 (13.4-17.0) mg/l (P = 0.001) and Cmin was 12.6 (9.1-13.9) versus 7.5 (4.9-8.6) mg/l (P = 0.002).

CONCLUSION

Patients with higher ritonavir concentrations are at a higher risk of experiencing neurological or gastrointestinal side-effects. Individualization of the dosage regimen, e.g. a downward titration of the ritonavir dose in patients with side-effects, guided by plasma level monitoring, may result in a substantial increase in the percentage of patients tolerating ritonavir without increasing the risk of treatment failure as a result of suboptimal systemic exposure.

Penetration of clindamycin and its metabolite N-demethylclindamycin into cerebrospinal fluid following intravenous infusion of clindamycin phosphate in patients with AIDS

Clindamycin, which is usually used in combination with pyrimethamine, has been proven effective in the treatment of cerebral toxoplasmosis in human immunodeficiency virus-infected patients. However, it is not known if clindamycin achieves inhibitory concentrations at the site of infection. Also, it has been hypothesized that the activity of clindamycin against Toxoplasma gondii may be due, at least in part, to a metabolite. We evaluated the penetration of clindamycin and its major metabolite, N-demethylclindamycin (NDC), into cerebrospinal fluid (CSF) of AIDS patients undergoing lumbar puncture for diagnostic purposes. A single, 1,200-mg dose of clindamycin was administered as a 45-min intravenous infusion beginning at 1.5 or 2.5 h before CSF sampling. The concentrations of clindamycin in CSF ranged from 0.091 to 0.429 mg/liter at 1.5 h and from 0.120 to 0.283 mg/liter at 2.5 h following the beginning of the infusion. The concentrations of clindamycin in CSF were well above the 50% inhibitory concentration of 0.001 mg/liter and the parasiticidal concentration of 0.006 mg/liter. NDC was undetectable both in plasma and in CSF. Our study provides a pharmacokinetic rationale for the clinical efficacy of clindamycin in the treatment of cerebral toxoplasmosis.

Molecular epidemiology in a cluster of cases of postoperative Pseudomonas aeruginosa endophthalmitis

Between September and October 1994 we observed three cases of Pseudomonas aeruginosa endophthalmitis in a single ophthalmology center. Endophthalmitis progressed rapidly following surgical intervention, and the three patients completely lost vision in the affected eye. Microbiological surveillance culture specimens were obtained from environmental sites, the operating team, intraocular lenses, irrigation fluids, and surgical equipment. P. aeruginosa was isolated from the internal tubing system of automated cataract surgical equipment. The strains of P. aeruginosa cultured from vitreous and anterior chamber specimens of case patients and from the surgical equipment were analyzed with pulsed-field gel electrophoresis. Genomic DNA typing of these isolates showed an identical banding pattern on ethidium bromide-stained gels. We believe that this is the first reported outbreak of P. aeruginosa endophthalmitis traced to automated surgical equipment. Genomic DNA typing emerged as a practical and reliable option for the epidemiological investigation of the outbreak.

Penetration of dapsone into cerebrospinal fluid of patients with AIDS

It has been proposed that dapsone in combination with pyrimethamine could be used for prophylaxis of both Pneumocystis carinii pneumonia and encephalitis due to Toxoplasma gondii. Ten patients with AIDS undergoing lumbar puncture for diagnostic purposes were studied in order to assess the penetration of dapsone into CSF. Blood and CSF samples were obtained between 3 and 72 h following administration. Six patients had received oral dapsone for at least 1 month at the dosage regimen of 100 mg twice of three times weekly and four patients had received a single oral 100 mg dose. Dapsone concentration in CSF ranged from 0.013 to 0.296 mg/L while concentrations in plasma ranged from 0.018 to 1.231 mg/L. The CSF:plasma concentration ratio ranged from 0.21 to 2.01. The MIC of dapsone in combination with pyrimethamine against T. gondii is unknown, and further data are required to confirm whether the CSF concentrations of dapsone found in our study are sufficient to inhibit T. gondii growth in patients infected with human immunodeficiency virus (HIV). The high interpatient variability of dapsone CSF concentrations warrants further studies in selected categories of patients with HIV infection.

Penetration of dapsone into pulmonary lining fluid of human immunodeficiency virus type 1-infected patients

We studied the penetration of dapsone into the epithelial lining fluid (ELF) of sixteen human immunodeficiency virus type 1-infected patients who had received the drug at a dose of 100 mg twice weekly as primary prophylaxis for Pneumocystis carinii pneumonia. Bronchoscopy, bronchoalveolar lavage (BAL), and venipuncture were performed for each patient at a specific time after administration of the last dose of dapsone. Dapsone concentrations in plasma and BAL were determined by high-performance liquid chromatography. The apparent volume of ELF recovered by BAL was determined by using urea as an endogenous marker. The mean concentrations of dapsone in ELF at 2 h (five patients), 4 h (three patients), 12 h (two patients), 24 h (three patients), and 48 h (three patients) were 0.95, 0.70, 1.55, 0.23, and 0.45 mg/liter, respectively, while concentrations in plasma were 1.23, 0.79, 1.31, 0.83, and 0.18 mg/liter, respectively. Dapsone concentrations in ELF were 76, 79, 115, 65, and 291% of those observed in plasma at the same times, respectively. These data show that dapsone is well distributed into ELF and that a twice-weekly 100-mg prophylactic regimen results in sustained concentrations in this compartment.

Population pharmacokinetics of dapsone administered biweekly to human immunodeficiency virus-infected patients

The population pharmacokinetics of dapsone were examined in human immunodeficiency virus-infected patients receiving dapsone at a dosage of 100 mg twice weekly for the prevention of Pneumocystis carinii pneumonia. Nonlinear mixed-effect modeling was used to determine the best pharmacostatistical model for the data. A one-compartment open model with first-order absorption and elimination was used as the structural pharmacokinetic model. Several covariates were tested for their influence on pharmacokinetic parameters. Rifampin was found to increase the values of clearance/bioavailability (CL/F) and volume of distribution/ bioavailability (V/F) by approximately 70%. CL/F and V/F were 1.83 liters/h and 69.6 liters, respectively, for patients not taking rifampin. The effect of rifampin on the pharmacokinetic parameters of dapsone was appreciably less than expected on the basis of studies with healthy volunteers. Increased bilirubin levels were associated with a significant decrease in the absorption rate constant (Ka). However, this finding may be considered clinically irrelevant because the post hoc Bayesian estimates of Ka for patients with high bilirubin levels ( > 1.2 mg/dl) were at the lower bound of the values for patients with normal bilirubin levels. The value of Ka was 0.957 h-1 for a patient with a bilirubin level of 0.7 mg/dl. After inclusion of covariates in the model, the interpatient variability was 35% for CL/F, not significant for V/F, and 85% for Ka. Simulation of plasma concentration-versus-time curves indicated that the administration of 100 mg of dapsone biweekly is associated with sustained dapsone levels in the plasma of the majority of the patients. Dosage adjustments for patients concomitantly treated with rifampin may be necessary.

Penetration of vancomycin into human lung tissue

Vancomycin penetration into lung tissue was evaluated in thirty patients following the administration of 1 g of vancomycin as a 1 h i.v. infusion. Mean concentrations (range) of vancomycin in lung tissue were 9.6 (6.3-12.1) mg/kg at 1h, 5.7 (4.7-7.4) mg/kg at 2 h, 4.2 (0.8-6.5) mg/kg at 3-4 h, 2.4 (1.4-4.7) mg/kg at 6 h, and 2.8 (0.9-7.8) mg/kg at 12 h after the end of infusion. Ratios of lung tissue to serum concentration ranged 0.24 to 0.41 at 1 and 12 h, respectively. One of six patients observed at 6 h, and 3 of 7 patients at 12 h did not have detectable levels of vancomycin in lung tissue. A 1 h iv infusion of a 1 g dose of vancomycin does not achieve sustained lung concentrations above the MIC for susceptible staphylococci over a dosing interval of 12 h. Therefore, a more appropriate modality of administration, such as continuous infusion, should be considered.

Prophylaxis with fluoroquinolones for bacterial infections in neutropenic patients: a meta-analysis

We conducted a two-part meta-analysis to assess the effectiveness of fluoroquinolones for preventing bacterial infections in granulocytopenic patients who are receiving chemotherapy for malignancies. Overall, 19 randomized studies met selection criteria and were included in this meta-analysis of 2,112 patients. Thirteen studies that compared the fluoroquinolones alone with control regimens (co-trimoxazole, oral nonabsorbable antibiotics, or placebo) and six studies that compared the fluoroquinolones plus prophylaxis for bacteremia due to gram-positive bacteria with control regimens (fluoroquinolones or oral nonabsorbable antibiotics) were included in the two meta-analyses. The results of the first meta-analysis indicate that fluoroquinolones alone are effective in preventing gram-negative bacteremia (overall odds ratio [OR], 0.09; 95% confidence interval [CI], 0.05-0.16; P < .001), but not gram-positive bacteremia (OR, 1.05; 95% CI, 0.76-1.45; P = .7), fever-related morbidity (OR, 0.76; 95% CI, 0.56-1.04; P = .09), and infection-related mortality (OR, 0.79; 95% CI, 0.47-1.34; P = .4). The results of the second meta-analysis indicate that a combination of fluoroquinolones plus prophylaxis for gram-positive bacteremia (penicillin, vancomycin, or macrolides) significantly reduces the occurrence of gram-positive bacteremia (OR, 0.46; CI, 0.33-0.63; P < .001) without affecting the incidence of fever-related morbidity (OR, 0.83; 95% CI, 0.62-1.13; P = .2) and infection-related mortality (OR, 0.74; 95% CI, 0.40-1.38; P = .3)

Twice-weekly dapsone for primary prophylaxis against Pneumocystis carinii pneumonia in HIV-1 infection: efficacy, safety and pharmacokinetic data

OBJECTIVES: In this study we evaluated the pharmacokinetics, efficacy and safety of dapsone given 100 mg twice weekly as primary prophylaxis against Pneumocystis carinii pneumonia (PCP) in patients with HIV-1 infection. METHODS: This was a prospective open trial, evaluating a total of 55 HIV-1-infected patients with CD4 cell counts below 200/mm3 and without previous episodes of PCP. Plasma concentrations of dapsone were determined with high-performance liquid chromatography (HPLC). After a mean follow-up of 471 days, the PCP rates per year of observation were 6.79%. Discontinuation of treatment as a result of severe side effects was required in four patients (7.5%). At steady state, mean plasma concentrations 24, 72, 96 and 144 h following the administration of dapsone were 1.46plus minus0.8, 0.28plus minus0.20, 0.30plus minus0.21 and 0.37plus minus0.27 mg/L, respectively. Dapsone plasma levels showed a high interpatient variability. The values for the pharmacokinetic parameters were comparable to those described for healthy volunteers. CONCLUSIONS: The administration of 100 mg twice weekly of dapsone seems appropriate to maintain effective plasma concentrations of the drug and to prevent PCP with good safety in patients with HIV-1-related immunodeficiency.

Pharmacokinetics of antimicrobial agents in the respiratory tract

The ability of antibiotics to penetrate into the respiratory tract has been investigated at several sites, namely, sputum and bronchial secretions, tissue homogenates, pleural fluid and, more recently, epithelial lining fluid and alveolar macrophages. The major reason for such investigations is that these data may be helpful to a more thorough understanding of drug distribution in the lung tissue and fluids and to a more accurate prediction of clinical outcome. However, the study of drug concentration at each of these sites presents problems in terms of methodology and data interpretation. The advantages and disadvantages of each of these methods are considered, and the data on penetration of betalactams, aminoglycosides, macrolides, fluoroquinolones and other antimicrobial agents (including antifungal and antiprotozoan drugs) are reviewed.

T cell blastogenic responses to Toxoplasma gondii trophozoites among HIV-infected patients

OBJECTIVE

To evaluate the cell-mediated immune response to Toxoplasma gondii (T. gondii) among HIV-infected patients.

METHODS

Forty HIV-infected patients were studied. Of them, 35 had antibodies to T. gondii and 5 had not. Nine of 35 patients with detectable serum Toxoplasma antibodies were classified as group A1 (CDC 1993), 10 as group B2, 6 as group B3, and 10 as group C3. Peripheral blood mononuclear cells (PBMCs) were obtained by Ficoll-Hypaque gradient centrifugation. Living Toxoplasma gondii trophozoites, herpes simplex virus (HSV), tetanus toxoid, and phytohemoagglutinin (PHA) were used in standard proliferation assays. Toxoplasma-responding blasts were expanded and assayed for antigen specificity and HLA restriction by proliferation assays. T cell subsets were analyzed using two-color flow cytometry.

RESULTS

Among patients with detectable Toxoplasma serum antibodies, significant PBMC proliferation in response to T. gondii trophozoites was observed in those classified in group A1 or B2 but not in those in groups B3 and C3. Toxoplasma-induced blasts from five of six patients after 7 days of culture and from five patients after 15 days of culture proliferated in response to T. gondii in the presence of either autologous or allogeneic PBMCs as antigen-presenting cells (APCs) and/or also proliferated in response to HSV. The surface markers of T. gondii-induced blasts showed a variable percentage of CD4 and CD8 activated cells.

CONCLUSIONS

T cell proliferative response to living trophozoites of T. gondii is lost only in patients with severe depletion of CD4 cells. PBMC proliferation was observed only in patients with previous T. gondii infection, but the T cell blasts generated showed a strong alloreactivity (proliferating in response to allogeneic irradiated PBMCs) and were apparently not antigen specific (proliferating also in response to HSV).

Pharmacokinetics of dapsone in human immunodeficiency virus-infected children

Dapsone, administered at various doses and schedules, has been proven to be a safe and effective alternative to trimethoprim-sulfamethoxazole for prevention of Pneumocystis carinii pneumonia (PCP) in adults with human immunodeficiency virus (HIV) infection. Dapsone is also recommended by the Centers for Disease Control for PCP prophylaxis in HIV-infected children. However, the suggested dosage regimen is based upon clinical experience with children with leprosy and dermatitis herpetiformis rather than pharmacokinetic and pharmacodynamic data obtained from the target patient population. In order to determine a rational dosage regimen that could be tested in clinical studies aimed at the evaluation of dapsone for the prevention of PCP in HIV-infected children, we studied the pharmacokinetics of dapsone following a 2-mg/kg of body weight oral dose in twelve HIV-positive children aged 9 months to 9 years. Plasma was collected at the following times after dapsone administration: 0, 2, 4, 6, 12, 24, 48, 72, and 96 h. The levels of dapsone in plasma were determined by high-performance liquid chromatography. Data were analyzed by noncompartmental methods. Expressed as means +/- standard deviations (ranges), the pharmacokinetic parameters were as follows: peak concentration in plasma, 1.12 +/- 0.48 (0.44 to 1.81) mg/liter; time to peak concentration in plasma, 3.8 +/- 1.3 (2 to 6) h; half-life at elimination phase, 24.2 +/- 7.1 (14.4 to 35.0) h; clearance from plasma divided by bioavailability (CL/F), 1.15 +/- 0.67 (0.37 to 2.63) ml/min/kg; and volume of distribution divided by bioavailability (V/F), 2.25 +/- 1.20 (1.00 to 4.57) liters/kg. Oral CL correlated negatively with age (r = 0.614 and P = 0.034), as did V (r = 0.631 and P = 0.028). As a consequence of the high interindividual variability in growth retardation, pharmacokinetic parameters correlated with measures of body development better than they did with age (e.g., for CL/F to height, r = 0.765 and P = 0.004, and for V/F to height, r = 0.748 and P = 0.005). Since oral CL from plasma and V were positively and highly correlated (r = 0.898 and P = 0.0001), a lower absolute F may be the cause, in part, of higher values for CL/F and V/F in smaller children. The results of this study warrant the testing of a 2-mg/kg dose of dapsone administered twice or thrice weekly to HIV-infected children. The monitoring of drug levels in plasma and dosage adjustment may be necessary for smaller children.

Stability of cefodizime in solution and compatibility with other injectable drugs

The stability of cefodizime in five intravenous infusion fluids (0.9% sodium chloride, 5% dextrose in water, 10% dextrose in water, 5% amino acid injection, 3% polygeline) was studied at room temperature and at 4 degrees C. The compatibility of cefodizime with commonly used injectable drugs (ranitidine, metoclopramide, folinic acid, furosemide, aminophilline, methylprednisolone, betamethasone, hydrocortisone, dexamethasone, ketoprofen, noramidopyrine, acetylcysteine, digoxin, diazepam, acetylsalicylic acid, chlorpromazine, clonidine, clomipramine) was studied in 0.9% sodium chloride and 5% dextrose at room temperature. At intervals during the storage periods (up to 24 hrs at room temperature; up to 6 days at 4 degrees C) color, clarity and solution pH were examined; cefodizime content was determined by a microbiological method. Cefodizime concentrations remained greater than 90% of the initial concentrations in all infusion fluids for at least 24 hrs at room temperature and 6 days at 4 degrees C. No visual changes or appreciable changes in pH were observed for any of the solutions. Immediate clouding was observed when chlorpromazine was combined with the solution of cefodizime. A color change was observed when acetylcysteine was mixed with cefodizime. An increase in pH was noted when aminophilline was added to the solution of cefodizime. However, cefodizime concentrations remained greater than 90% of the initial concentrations of the solutions after mixture with all the tested drugs for at least 24 hrs at room temperature.(ABSTRACT TRUNCATED AT 250 WORDS)

The fluoroquinolones as treatment for infections caused by gram-positive bacteria

The fluoroquinolones have become attractive options as treatment for a broad range of infections caused by Gram-negative bacteria. However, the value of these antibiotics to patients with infections caused by Gram-positive pathogens remains controversial. Experience with quinolones as therapy for skin and skin structure infections, osteomyelitis and peritonitis in patients receiving continuous ambulatory peritoneal dialysis suggests that the concerns which have been expressed about the use of these agents against methicillin-resistant Staphylococcus aureus (MRSA), Staphylococcus epidermidis and streptococci are justified; indeed, the frequent emergence of quinolone-resistant strains of MRSA and coagulase-negative staphylococci either during or following treatment is now well documented. The fluoroquinolones should be prescribed with caution to patients with community-acquired pneumonia or whenever severe infection of pneumococcal aetiology is proven or suspected. As prophylaxis for the granulocytopenic patient, quinolones such as norfloxacin and ciprofloxacin have been shown to be effective in reducing the incidence of morbidity attributable to Gram-negative bacteria, but they have not significantly affected the incidence of infection caused by Gram-positive bacteria. In the treatment of febrile episodes in the neutropenic patient, ciprofloxacin, the quinolone investigated most extensively in this clinical setting, produced high cure rates only when it was combined with an antibiotic which was predictably active against Gram-positive organisms. We review here the role of currently-available fluoroquinolones (norfloxacin, enoxacin, pefloxacin, ofloxacin and ciprofloxacin) as treatment for these and other infections.

Availability of synthetic salmon calcitonin in tissue fluid after a single intravenous dose

To obtain further information about the availability of salmon calcitonin in the biophase compartment that surrounds the receptor site, salmon calcitonin concentrations in plasma and skin blister fluid (SBF) after a single i.v. dose of 100 IU synthetic salmon calcitonin were compared in 15 healthy volunteers. Serial blood and SBF samples were collected before and up to 8 h after administration and calcitonin was determined by a specific RIA. The maximum concentration in plasma was 225 pg.ml-1 (in the first sample at 15 min), whereas in SBF the mean peak of 84 pg.ml-1 was reached after about 30 min. The distribution of salmon calcitonin into SBF, defined as the ratio of the AUCs in SBF and plasma, was 1.5. The kinetic profiles of salmon calcitonin in plasma and interstitial fluid were different. Calcitonin in plasma peaked and then levelled out, while in SBF it persisted longer than in plasma. This is the first report of the distribution of salmon calcitonin into blister fluid.