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Background The advocated pharmacokinetic/pharmacodynamic (PK/PD) target for vancomycin, AUC/MIC ≥ 400 mg·h/L, may not be reached with a conventional fixed starting dose of 1000 mg in critically ill patients, but increasing the dose may cause nephrotoxicity. Objectives To evaluate the effect of a weight-based loading dose of 25 mg/kg vancomycin on PK/PD target attainment in the first 24 h (AUC0–24) in critically ill patients and to evaluate whether this increases the risk of acute kidney injury (AKI). Patients and methods A prospective observational before/after study was performed in ICU patients, comparing the percentage of vancomycin courses with AUC0–24 ≥ 400 mg·h/L and the incidence of AKI, defined as worsening of the risk, injury, failure, loss of kidney function and end-stage kidney disease (RIFLE) score. The conventional dose group received 1000 mg of vancomycin as initial dose; the loading dose group received a weight-based loading dose of 25 mg/kg. A population PK model developed using non-linear mixed-effects modelling was used to estimate AUC0–24 in all patients. Results One hundred and four courses from 82 patients were included. With a loading dose, the percentage of courses achieving AUC0–24 ≥ 400 mg·h/L increased significantly from 53.8% to 88.0% (P = 0.0006). The percentage of patients with new-onset AKI was not significantly higher when receiving a 25 mg/kg loading dose (28.6% versus 37.8%; P = 0.48). However, the risk of AKI was significantly higher in patients achieving AUC0–24 > 400 mg·h/L compared with patients achieving AUC Conclusions A weight-based loading dose of 25 mg/kg vancomycin led to significantly more patients achieving AUC0–24 ≥ 400 mg·h/L without increased risk of AKI. However, some harm cannot be ruled out since higher exposure was associated with increased risk of AKI.

Background Diagnosing urinary tract infections (UTIs) in nursing home residents is complex, as specific urinary symptoms are often absent and asymptomatic bacteriuria (ASB) is prevalent. The aim of this study was to assess the sensitivity of blood C-reactive protein (CRP) and procalcitonin (PCT), measured by point-of-care tests (PoCTs), to diagnose UTIs in this setting. Methods Elderly residents (≥65 years old) with a suspected UTI were recruited from psychogeriatric, somatic, or rehabilitation wards across 13 participating nursing homes. CRP and PCT were tested simultaneously in the same study participants. To assess the tests’ sensitivities, a stringent definition of “true” UTI was used that included the presence of symptoms, urinary leucocytes, a positive urine culture, and symptom resolution during antibiotic treatment covering isolated uropathogen(s). The original sample size was 440 suspected UTI episodes, in order to detect a clinically relevant sensitivity of at least 65% when calculated using the matched analysis approach to compare both PoCTs. Results After enrollment of 302 episodes (68.6% of the planned sample size), an unplanned and funder-mandated interim analysis was done, resulting in premature discontinuation of the study for futility. For 247 of 266 eligible episodes, all mandatory items required for the true UTI definition (92.9%) were available. In total, 49 episodes fulfilled our stringent UTI definition (19.8%). The sensitivities of CRP (cut-off, 6.5 mg/L) and PCT (cut-off, 0.025 ng/mL) were 52.3% (95% confidence interval [CI], 36.7–67.5%) and 37.0% (95% CI, 23.2–52.5%), respectively. Conclusions Our results indicate that CRP and PCT are not suitable tests for distinguishing UTI and ASB in nursing home residents. Clinical Trials Registration Netherlands Trial Registry NL6293., Blood C-reactive protein and procalcitonin measured by point-of-care tests are not suitable to distinguish urinary tract infection and asymptomatic bacteriuria in nursing home residents.

International audience; Human bronchial epithelial (HBE) cells play an essential role during bacterial infections of the airways by sensing pathogens and orchestrating protective immune responses. We here sought to determine which metabolic pathways are utilized by HBE cells to mount innate immune responses upon exposure to a relevant bacterial agonist. Stimulation of HBE cells by the bacterial component flagellin triggered activation of the mTOR pathway resulting in an increased glycolytic flux that sustained the secretory activity of immune mediators by HBE cells. The mTOR inhibitor rapamycin impeded glycolysis and limited flagellin-induced secretion of immune mediators. The role of the mTOR pathway was recapitulated in vivo in a mouse model of flagellin-triggered lung innate immune responses. These data demonstrate that metabolic reprogramming via the mTOR pathway modulates activation of the respiratory epithelium, identifying mTOR as a potential therapeutic target to modulate mucosal immunity in the context of bacterial infections.

Background Diagnosing urinary tract infections (UTI) in nursing home residents is complex, due to frequent non-specific symptomatology and asymptomatic bacteriuria. The objective of this study was to explore health care professionals’ perceptions of the proposed use of inflammatory marker Point-Of-Care Testing (POCT) in this respect. Methods We conducted a qualitative inquiry (2018–2019) alongside the multicenter PROGRESS study (NL6293), which assessed the sensitivity of C-reactive protein and procalcitonin POCT in UTI. We used semi-structured face-to-face interviews. The participants were physicians (n = 12) and nurses (n = 6) from 13 nursing homes in the Netherlands. Most respondents were not familiar with inflammatory marker POCT, while some used POCT for respiratory tract infections. Both the interview guide and the analysis of the interview transcripts were based on the Consolidated Framework for Implementation Research. Results All respondents acknowledged that sufficiently sensitive POCT could decrease diagnostic uncertainty to some extent in residents presenting with non-specific symptoms. They primarily thought that negative test results would rule out UTI and justify withholding antibiotic treatment. Secondly, they described how positive test results could rule in UTI and justify antimicrobial treatment. However, most respondents also expected new diagnostic uncertainties to arise. Firstly, in case of negative test results, they were not sure how to deal with residents’ persisting non-specific symptoms. Secondly, in case of positive test results, they feared overlooking infections other than UTI. These new uncertainties could lead to inappropriate antibiotics use. Therefore, POCT was thought to create a false sense of confidence. Conclusions Our study suggests that inflammatory marker POCT will only improve UTI management in nursing homes to some extent. To realize the expected added value, any implementation of POCT requires thorough guidance to ensure appropriate use. Developing UTI markers with high negative and positive predictive values may offer greater potential to improve UTI management in nursing homes.

Seasonal human influenza viruses continually change antigenically to escape from neutralizing antibodies. It remains unclear how genetic variation in the intrahost virus population and selection at the level of individual hosts translates to the fast-paced evolution observed at the global level because emerging intrahost antigenic variants are rarely detected. We tracked intrahost variants in the hemagglutinin and neuraminidase surface proteins using longitudinally collected samples from 52 patients infected by A/H3N2 influenza virus, mostly young children, who received oseltamivir treatment. We identified emerging putative antigenic variants and oseltamivir-resistant variants, most of which remained detectable in samples collected at subsequent days, and identified variants that emerged intrahost immediately prior to increases in global rates. In contrast to most putative antigenic variants, oseltamivir-resistant variants rapidly increased to high frequencies in the virus population. Importantly, the majority of putative antigenic variants and oseltamivir-resistant variants were first detectable four or more days after onset of symptoms or start of treatment, respectively. Our observations demonstrate that de novo variants emerge, and may be positively selected, during the course of infection. Additionally, based on the 4–7 days post-treatment delay in emergence of oseltamivir-resistant variants in six out of the eight individuals with such variants, we find that limiting sample collection for routine surveillance and diagnostic testing to early timepoints after onset of symptoms can potentially preclude detection of emerging, positively selected variants.

Additional file 1. Interview guide

Additional file 2. Coding tree

Background: Diagnosis of malaria in pregnancy is problematic due to the low sensitivity of conventional diagnostic tests (rapid diagnostic test and microscopy), which is exacerbated due to low peripheral parasite densities, and lack of clinical symptoms. In this study, six potential biomarkers to support malaria diagnosis in pregnancy were evaluated.Methods: Blood samples were collected from pregnant women at antenatal clinic visits and at delivery. Microscopy and real-time PCR were performed for malaria diagnosis and biomarker analyses were performed by ELISA (interleukin 10, IL-10; tumor necrosis factor-α, TNF-α; soluble tumor necrosis factor receptor II, sTNF-RII; soluble fms-like tyrosine kinase 1, sFlt-1; leptin and apolipoprotein B, Apo-B). A placental biopsy was collected at delivery to determine placental malaria.Results: IL-10 and sTNF-RII were significantly higher at all time-points in malaria-infected women (p p p = 0.003 for IL-10 and sTNF-RII respectively). IL-10 levels at delivery, but not during pregnancy, were negatively associated with birth weight. A prediction model was created using IL-10 and sTNF-RII cut-off points. For primigravidae the model had a sensitivity of 88.9% (95%CI 45.7–98.7%) and specificity of 83.3% (95% CI 57.1–94.9%) for diagnosing malaria during pregnancy. For secundi- and multigravidae the sensitivity (81.8% and 56.5% respectively) was lower, while specificity (100.0% and 94.3% respectively) was relatively high. Sub-microscopic infections were detected in 2 out of 3 secundi- and 5 out of 12 multigravidae.Conclusions: The combination of biomarkers IL-10 and sTNF-RII have the potential to support malaria diagnosis in pregnancy. Additional markers may be needed to increase sensitivity and specificity, this is of particular importance in populations with sub-microscopic infections or in whom other inflammatory diseases are prevalent.

Background Diagnosis of malaria in pregnancy is problematic due to the low sensitivity of conventional diagnostic tests (rapid diagnostic test and microscopy), which is exacerbated due to low peripheral parasite densities, and lack of clinical symptoms. In this study, six potential biomarkers to support malaria diagnosis in pregnancy were evaluated. Methods Blood samples were collected from pregnant women at antenatal clinic visits and at delivery. Microscopy and real-time PCR were performed for malaria diagnosis and biomarker analyses were performed by ELISA (interleukin 10, IL-10; tumor necrosis factor-α, TNF-α; soluble tumor necrosis factor receptor II, sTNF-RII; soluble fms-like tyrosine kinase 1, sFlt-1; leptin and apolipoprotein B, Apo-B). A placental biopsy was collected at delivery to determine placental malaria. Results IL-10 and sTNF-RII were significantly higher at all time-points in malaria-infected women (p

Background Human Rhinovirus (HRV) is responsible for the majority of common colds and is frequently accompanied by secondary bacterial infections through poorly understood mechanisms. We investigated the effects of experimental human HRV serotype 16 infection on the upper respiratory tract microbiota. Methods Six healthy volunteers were infected with HRV16. We performed 16S ribosomal RNA-targeted pyrosequencing on throat swabs taken prior, during and after infection. We compared overall community diversity, phylogenetic structure of the ecosystem and relative abundances of the different bacteria between time points. Results During acute infection strong trends towards increases in the relative abundances of Haemophilus parainfluenzae and Neisseria subflava were observed, as well as a weaker trend towards increases of Staphylococcus aureus. No major differences were observed between day-1 and day 60, whereas differences between subjects were very high. Conclusions HRV16 infection is associated with the increase of three genera known to be associated with secondary infections following HRV infections. The observed changes of upper respiratory tract microbiota could help explain why HRV infection predisposes to bacterial otitis media, sinusitis and pneumonia. Electronic supplementary material The online version of this article (doi:10.1186/s12879-015-1081-y) contains supplementary material, which is available to authorized users.

In response to the Ebola virus disease (EVD) outbreak in West Africa, the World Health Organization has advised all nations to prepare for the detection, investigation and management of confirmed and suspected EVD cases in order to prevent further spread through international travel. To gain insights into the state of preparedness of European hospitals, an electronic survey was circulated in AugustSeptember 2014 to 984 medical professionals representing 736 hospitals in 40 countries. The survey addressed the willingness and capacity to admit patients with suspected EVD as well as specific preparedness activities in response to the current Ebola crisis. Evaluable responses were received from representatives of 254 (32%) hospitals in 38 countries, mostly tertiary care centres, of which 46% indicated that they would admit patients with suspected EVD. Patient transfer agreements were in place for the majority of hospitals that would not admit patients. Compared with non-admitting hospitals, admitting hospitals were more frequently engaged in various preparedness activities and more often contained basic infrastructural characteristics such as admission rooms and laboratories considered important for infection control, but some gaps and concerns were also identified. The results of this survey help to provide direction towards further preparedness activities and prioritisation thereof.

The biological control of stump sprouting in American bird cherry (Prunus serotina) and poplar (Populus euramericana) by applying a mycelium suspension of Chondrostereum purpureum is outlined. This fungus is being commercially deployed as a mycoherbicide under the brand name BioChon in order to prevent stump sprouting in hardwoods. It acts as a wood decay promoter. Effectivity of BioChon applied to control stump sprouting in P. serotina generally results in a kill of about 95% two years after treatment, and it appears to be as effective on poplar. Research on C. purpureum is also being carried out in Canada to control unwanted hardwoods in silviculture, in Switzerland for vegetation management, and in New Zealand to control imported woody weeds in pastures. Infection danger to non-target plants due to use of this pathogen as a mycoherbicide seems to be negligible in most cases. Worldwide marketing of the fungus is discussed.

Three hundred sixty Enterobacteriaceae and nonfermenting gram-negative bacilli, isolated during one week in May 2004 at five hospitals in Amsterdam, The Netherlands, were evaluated for the presence of extended-spectrum beta-lactamases (ESBLs). A prevalence of 7.8% was found, in contrast to the 1% observed in 1997. CTX-M ESBLs dominated, and four types were identified in 18 isolates.

Quantitative buffy coat (QBC) analysis is a well accepted tool for the sensitive and rapid diagnosis of malaria [1]. It can also detect several other microorganisms in human specimens, including microfilaria, trypanosomes, Leishmania amastigotes, Trichomonas trophozoites, Babesia piroplasms, Borrelia spirochetes and leptospires [2, 3, 4, 5, 6, 7, 8]. Here, we present a case in which QBC analysis facilitated the rapid detection of pneumococcemia. A 35-year-old man presented at the emergency department with severe headache and cold extremities. He had arrived in the Netherlands from Burkina Faso 3 weeks earlier and had no permanent living address. He was conscious but confused and disorientated. Initial examination revealed a heart rate of 100 bpm, unstable blood pressure (ranging from 80/40 to 200/110 mmHg), and a temperature of 36.4 C. Further physical examination revealed nuchal rigidity and paresis of the left leg. Petechiae were not observed. Lung sounds were normal. Laboratory investigations revealed a leukocyte count of 8.1 109/l (78% polymorphs, 8% bands, 10% metamyelocytes). Numerous Howell-Jolly bodies were observed. Erythrocyte sedimentation rate was 2 mm/first hour, platelet count 33 109/l, prothrombin time 54.6 s, activated partial thromboplastin time 140 s, fibrinogen level 0.3 g/l. C-reactive protein level was 211 mg/l and creatinine level 362 mol/l. Lumbar puncture was not performed because of presumed disseminated intravascular coagulation. A presumptive diagnosis of bacterial sepsis with meningitis was made. Empirical antibacterial therapy with amoxicillin, ceftriaxone and gentamicin was commenced after blood cultures were drawn. As part of the patient’s laboratory work-up, the parasitology lab was asked to perform diagnostic tests for malaria. Thick and thin blood smears were prepared from finger-prick blood. Microscopic investigation of smears according to World Health Organization standard methods did not reveal malaria parasites. Malaria pigment was, however, observed in some peripheral blood phagocytes, indicating that the patient had been infected with malaria in the recent past. EDTA-anticoagulated blood obtained by venepuncture was used to perform QBC analysis. A QBC tube (Becton Dickinson, USA) was filled with blood (approximately 55–65 l) and mixed with acridineorange dye, which coats the interior of the tube [7]. The tube was stoppered and a plastic float was inserted. The tube was centrifuged at 12,000 rpm for 5 min in a capillary tubes centrifuge (Becton Dickinson) and examined by fluorescence microscopy (Olympus BH-2; Olympus America, USA) with a 50 oil immersion lens. The entire erythrocyte layer was examined by revolving the tube and examining all sections. No malaria parasites were observed. The leucocyte, platelet, and plasma layers were additionally examined for signs of other infections e.g. borreliosis, trypanosomiasis and leishmaniasis. Just above the plasma-platelet interface, a dense concentration of brightly luminescent structures was observed, which morphologically resembled diplococci (Fig. 1A). No other abnormalities were observed. Subsequent to the QBC analysis, direct Gram stain was performed on a thin blood smear prepared from fingerprick blood. After a thorough search, a few encapsulated gram-positive diplococci resembling Streptococcus pneumoniae were observed both extracellularly and intracellularly in granulocytes (Fig. 1B). The remainder of the EDTA-anticoagulated blood was inoculated onto blood agar plates with antibiotic-impregnated disks. Overnight culture yielded penicillin-sensitive Streptococcus pneumoniae. P. C. Wever ()) · E. R. Heddema · M. D. de Jong · T. van Gool Section of Parasitology, Department of Medical Microbiology, Academic Medical Centre, P.O. Box 22660, 1100 DD Amsterdam, The Netherlands e-mail: p.c.wever@amc.uva.nl Tel.: +31-20-5669111 Fax: +31-20-6979271

230 neutropenic episodes in 84 patients with acute myeloid leukemia receiving selective intestinal decontamination were studied to evaluate the ability of surveillance cultures to monitor the efficacy of microbial suppression, to identify causative organisms in case of fever, and to predict infection due to potential pathogens (i.e. Staphylococcus aureus and aerobic Gram-negative bacteria). Most cultures became negative soon after the administration of prophylactic antibiotics and there were only few persistent colonizations. 14 potential pathogens resistant to the intestinal decontamination regimen were isolated in surveillance cultures, none of which caused infection. Of the 212 febrile episodes, only 22 were caused by a microbiologically documented infection with potential pathogens. Most microbiologically documented infections were caused by organisms not routinely identified by surveillance cultures, indicating efficient selective intestinal decontamination. Only 9 (41%) of the 22 infections with potential pathogens were predicted by surveillance cultures. We conclude that surveillance cultures are of limited use in predicting infection or identifying causative organisms of fever in neutropenic patients receiving selective intestinal decontamination. However, they are useful in monitoring the efficacy of microbial suppression. One set of surveillance cultures each week after the disappearance of potential pathogens would be sufficient

Introduction Primary infection with human immunodeficiency virus (HIV) has been defined by the Centers for Disease Control (CDC) as a mononucleosis-like illness, with or without aseptic meningitis, associated with seroconversion for HIV antibody.' Since the introduction of this definition in 1986, it has become clear that symptomatic primary human immunodeficiency virus type 1 (HIV-1) infection can be a recognisable clinical syndrome with distinct differences from Epstein-Barr virus (EBV) infectious mononucleosis. Moreover, the CDC definition does not encompass the full clinical spectrum of primary HIV-1 infection. We will outline the syndrome of primary infection with HIV-1 by reviewing clinical, virological and immunological features. Differential diagnostic considerations will also be discussed.

In a 32-year-old woman suffering from severe diarrhoea, eosinophilic infiltration of colonic mucosa and a peripheral eosinophilia, microbiological investigations only revealed large numbers of Enterobius vermicularis (pinworm) in the faeces. Treatment with mebendazole resulted in a rapid resolution of symptoms and disappearance of the eosinophilia, which strongly suggested a causative role of this pinworm in the clinical syndrome of the patient. E. vermicularis is generally regarded as an innocent nematode, which at most causes perianal pruritus due to migration of worms from the colon and expulsion of eggs onto the perianal skin. Although the pinworm maturates and lives in the gut, gastrointestinal symptoms have seldom been reported. E. vermicularis infection should be considered in patients with unexplained eosinophilic enteritis.

Background: A 78-year-old female was referred to our hospital with complaints of chest pain, dyspnea and dysphagia. Her medical history was unremarkable

We describe a highly sensitive assay for quantitation of varicella-zoster virus (VZV) DNA in blood, involving PCR amplification, solution hybridization with Tris-(2,2′-bipyridine)-ruthenium(II) chelate-labeled probes, and measurement by electrochemiluminescence (ECL). Extraction and amplification efficiencies were monitored by the inclusion of internal control (IC) DNA, mimicking the VZV target, in the DNA extraction. Viral DNA load was calculated from the ratio of VZV and IC ECL signals. The lower limit of sensitivity was 20 VZV DNA copies/ml of plasma or serum and 80 copies/ml of whole blood. In reconstruction experiments, expected and calculated VZV DNA loads were in excellent accordance. Blood specimens from 42 VZV-infected patients were tested for the presence of VZV DNA and showed detection rates of 86% in patients with varicella and 81% in patients with herpes zoster. In specimens obtained during the first week after onset of the rash, detection rates were 100 and 89%, respectively. Viral DNA was detected in all immunocompromised patients with herpes zoster, emphasizing the risk of disseminated disease in this patient group. VZV DNA load was similar in patients with varicella and multidermatomal herpes zoster and lower in patients with unidermatomal zoster. Despite the cell-associated nature of the virus, VZV DNA was detected in serum and plasma at high copy numbers, and at similar frequencies compared to whole-blood specimens. Quantitation of VZV DNA in blood is of potential importance for diagnosis and clinical management of VZV-infected patients. Plasma and serum provide convenient matrices for this purpose.

For scarce antigens or antigens which are embedded in a dense macromolecular structure, on-section labeling, the first method of choice, is not always successful. Often, the antigen can be localized by immunofluorescence microscopy, usually by a pre-embedding labeling method. Most of these methods lead to loss of ultrastructural details and, hence, labeling at electron microscope resolution does not add essential information. The scope of this paper is to compare five permeabilization methods for pre-embedding labelling for electron microscopy. We aim for a method that is easy to use and suitable for routine investigations. For our ongoing work, special attention is given to labeling of the cell nucleus. Accessibility of cytoplasmic and nuclear antigens is monitored with a set of different marker antibodies. From this investigation, we suggest that prefixation with formaldehyde/glutaraldehyde is necessary to stabilize the ultrastructure before using a detergent (Triton X-100 or Brij 58) to permeabilize or remove the membranes. The experimental conditions for labeling should be checked first with fluorescence or fluorescence-gold markers by fluorescence microscopy. Then either ultrasmall gold particles (with or without fluorochrome) with silver enhancement or, if the ultrasmall gold particles are obstructed, peroxidase markers are advised. The most promising technique to localize scarce antigens with good contrast is the combination of a pre-embedding peroxidase/tyramide-FITC or -biotin labeling followed by an on-section colloidal gold detection.

HIV-1 RNA levels as measured by two commercially available quantitative assays were compared before and during zidovudine treatment. HIV-1 RNA levels were measured in stored serum samples from 24 Dutch zidovudine-treated participants of a zidovudine efficacy study (European-Australian Collaborative Group Study 017) at weeks -3, 0, 4 and 8, using quantitative nucleic acid sequence-based amplification (NASBA; Organon Technika) and quantitative reverse transcriptase-polymerase chain reaction (Amplicor; Roche Molecular Systems). HIV-1 RNA copy numbers and changes from baseline as measured by each assay were compared. Individual responses to treatment were compared using definitions based on the within-subject variation of each assay. Before treatment, HIV-1 RNA levels as measured by NASBA were 0.49 logs higher than the levels measured by the Amplicor assay (95% confidence interval (CI) 0.32-0.66). During treatment, this difference decreased significantly to 0.27 logs (95% CI 0.01-0.53; difference 0.22 logs; 95% CI 0.05-0.37). The smaller difference between the results of the two assays during treatment was a consequence of a larger decline in RNA level as measured by NASBA compared with that measured by the Amplicor assay (mean change after 4 weeks 0.77 and 0.49 logs, respectively). At week 8, the mean HIV-1 RNA level was still significantly below baseline values as measured by NASBA, but not when measured by the Amplicor assay. Discrepancies in individual responses as measured by the two assays were also observed. In conclusion, marked differences exist between the NASBA and Amplicor quantitative assays, in both HIV-1 RNA copy numbers without treatment and changes in RNA level during treatment. These differences should be considered in interpreting analyses of clinical trials and relationships between HIV-1 RNA level and clinical outcome, as well as in the use of RNA level in the management of HIV-infected patients.

A simple approach for the determination of drug susceptibilities by using human immunodeficiency virus type 1 (HIV-1) RNA from the sera of patients is described. HIV-1 RNA was extracted from patient sera, and the 5' part of the reverse transcriptase (RT) gene was transcribed into DNA and amplified in a nested PCR. The amplified fragment covers the 3' part of the protease gene and amino acids 1 to 304 of the RT gene. This fragment can be introduced through homologous recombination, as described previously, into a novel HIV-1 reference strain (pHXB2 delta 2-261RT) from which amino acids 2 to 261 of RT have been deleted. The resulting recombinant virus expresses all properties of the HXB2 reference strain except for those encoded by the introduced part of the patient RT gene. Recombinant viruses were subsequently tested for drug susceptibility in a microtiter format killing assay [3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay] as well as in the standard HeLa CD4+ plaque reduction assay. Similar susceptibility profiles were obtained by each assay with recombinant viruses derived from patients receiving alternating nevirapine and zidovudine treatment or lamivudine-zidovudine combination therapy. In conclusion, this approach enables high-through-put determination of the drug susceptibilities of serum RNA-derived RT genes, independent of the patient's viral background, and generates the possibility of relating changes in susceptibility to changes in viral genotypes.

Nevirapine is a non-nucleoside reverse transcriptase inhibitor of HIV-1 which exhibits synergy in vitro with zidovudine (ZDV) and also is active against ZDV-resistant HIV. We evaluated the activity and safety of nevirapine in combination with ZDV in patients receiving long-term ZDV therapy.We conducted a randomized, open-label, controlled 28-week study of nevirapine (200 mg daily for 2 weeks followed by 200 mg twice daily for 26 weeks) and continued ZDV (500-600 mg daily) versus continued ZDV alone in 49 HIV-1 p24 antigenaemic patients with CD4+ lymphocyte counts500 x 10(6)/l and who had been treated with ZDV for at least 6 months.Addition of nevirapine to ZDV resulted in a significant and rapid reduction in circulating RNA load (mean, 0.65), a mean CD4+ lymphocyte rise of 34 x 10(6)/l, a reduction in serum beta 2-microglobulin and a median fall in immune complex dissociated p24 antigen levels of 69%. These changes remained statistically significant for 4, 4, 12 and at least 28 weeks, respectively. The principal adverse event due to nevirapine was a hypersensitivity reaction comprising rash with or without fever and mucositis in eight (32%) patients, which was dose-limiting in seven patients.Nevirapine exhibits significant although transient anti-HIV activity in ZDV-pretreated patients but its use is frequently associated with a hypersensitivity reaction.

Recent reports indicate a high rate of viral replication during all phases of HIV-1 infection. This rapid turnover presents a continuous drive towards mutations in the HIV-1 genome, which may include those conferring drug resistance. Although the natural occurrence of drug-resistant variants has been reported, the implication on viral kinetics of the subsequent introduction of a selective pressure, in the form of antiviral treatment, remains to be elucidated. We analysed proviral DNA from nine previously untreated participants in a nevirapine study for the presence of the nevirapine resistance-conferring tyrosine to cysteine substitution at codon 181 of HIV-1 reverse transcriptase. In one individual, a minor proviral subpopulation containing this mutation was detected. A rapid selective outgrowth of this minor drug-resistant subpopulation during subsequent treatment with nevirapine was evidenced by a nearly complete replacement of the wild-type HIV-1 RNA population by 181-cysteine variant virus in serum within 1 week, and a reversal of the proportions of tyrosine- and cysteine-encoding proviruses within 2 weeks of treatment, which contrasted with other subjects tested. The rapid emergence of a drug-resistant virus variant clearly resulted in a lack of replication inhibition by nevirapine: whereas other patients demonstrated a median 1.2 log10 decrease in serum HIV-1 RNA load during the first week of treatment, an increase of 0.6 log10 was observed in this patient. The extensive repercussions for subsequent treatment of even a minor subpopulation of naturally occurring drug-resistant variants observed in this study must be considered in future therapeutic strategies.

The potential use of an alternating treatment strategy with nevirapine and zidovudine in prolonging the antiretroviral effects of nevirapine was evaluated. Ten human immunodeficiency virus type 1 (HIV-1)-infected p24 antigen-positive persons who had not received prior antiretroviral therapy were treated for 9-13 weeks with an alternating regimen of 1 week of nevirapine (200 mg/day) and 3 weeks of zidovudine (600 mg/day). Serum p24 antigen levels declined during the first week of nevirapine treatment (median, 59%); however, subsequent courses of nevirapine were characterized by rising p24 antigen levels, while antigen levels remained stable or declined during zidovudine treatment. Serum beta 2-microglobulin levels and CD4+ cell counts exhibited similar responses. HIV-1 isolates obtained from 2 patients revealed 40- and 1000-fold reductions in nevirapine sensitivity after 8 weeks. These findings demonstrate that alternating treatment with zidovudine and nevirapine does not prolong the effectiveness of nevirapine and does not prevent the development of nevirapine resistance.

230 neutropenic episodes in 84 patients with acute myeloid leukemia receiving selective intestinal decontamination were studied to evaluate the ability of surveillance cultures to monitor the efficacy of microbial suppression, to identify causative organisms in case of fever, and to predict infection due to potential pathogens (i.e. Staphylococcus aureus and aerobic Gram-negative bacteria). Most cultures became negative soon after the administration of prophylactic antibiotics and there were only few persistent colonizations. 14 potential pathogens resistant to the intestinal decontamination regimen were isolated in surveillance cultures, none of which caused infection. Of the 212 febrile episodes, only 22 were caused by a microbiologically documented infection with potential pathogens. Most microbiologically documented infections were caused by organisms not routinely identified by surveillance cultures, indicating efficient selective intestinal decontamination. Only 9 (41%) of the 22 infections with potential pathogens were predicted by surveillance cultures. We conclude that surveillance cultures are of limited use in predicting infection or identifying causative organisms of fever in neutropenic patients receiving selective intestinal decontamination. However, they are useful in monitoring the efficacy of microbial suppression. One set of surveillance cultures each week after the disappearance of potential pathogens would be sufficient.

The high water permeability of kidney proximal tubules is of paramount importance for isotonic reabsorption of 70% of the glomerular filtrate, and water channels have been postulated to account for the high water permeability. Target analysis following radiation inactivation was used to probe the molecular size of the water channel. Samples of brush border membranes from rat renal cortex were subjected to 3-MeV electron pulses from the Van de Graaff accelerator at a temperature of -130 degrees C. The inactivation of the renal brush border enzymes, alkaline phosphatase, and maltase was used for internal standardization of accumulated dose measurements in target analysis of the water channel. Osmotic water permeability was measured by following the change in scattered light intensity upon rapid mixing of vesicles with a hypertonic solution using stopped-flow spectrophotometry. The vesicle shrinkage response was biphasic and the rate of the fast phase decreased dose dependently by irradiation corresponding to a target size of 30 +/- 3.5 kDa. The total change in scattered light intensity was unaltered, indicating that irradiation did not destroy the lipid barrier. Our results provide strong support for the hypothesis that the high osmotic water permeability of renal proximal tubules results from a water channel-specific protein with a functional unit of 30 kDa.

Since the introduction of aerosolised pentamidine for prophylaxis against Pneumocystis carinii pneumonia (PCP) in HIV-seropositive persons and patients with AIDS, an increasing number of cases of atypical manifestations of infection with Pneumocystis carinii have been reported in the United States, viz. upper lobe pneumonia, extrapulmonary Pneumocystis carinii infection and spontaneous pneumothorax. An association between these atypical manifestations of Pneumocystis carinii infection and the use of aerosolised pentamidine seems likely. This report is the first description in the Netherlands of an atypical Pneumocystis carinii infection in an AIDS patient while using aerosolised pentamidine for prophylaxis against PCP. Since aerosolised pentamidine for prophylaxis against PCP is increasingly being used in the Netherlands, a rise in incidence of atypical manifestations of Pneumocystis carinii infection can be expected.

Biological control of Primus serotina, a forest weed in the Netherlands, by means of the silverleaf fungus Chondrostereum purpureum is studied. The fungus is a common saprophyte in dead wood. As a wound invader, it can cause silverleaf disease of P. serotina and fruit trees. Biological control of P. serotina within a forest leads to infection, sporulation and spore dispersal, and thus creates a risk to fruit trees outside the forest. To estimate this risk, spore immission was calculated by means of the Gaussian plume model (GPM). A short-term version of the GPM was used to calculate the ‘absolute risk’ as the spore density outside the forest due to biological control. Mean spore densities at 5000 m distance downwind of the forest were at least one order of magnitude lower than at 500 m. Maximum spore density at 5000 m downwind of the forest was calculated to be 32 spores.m-3, and at 500 m 141 spores.m-3. It was concluded that risk to fruit trees was appreciable at 500 m distance and negligible at...

The risk-assessment study consisted of field experiments, surveys, and simulations, using models current in epidemiology, micrometeorology, and air pollution theory. This paper gives an overview, foregoing many aspects published elsewhere

Although both structured programming (particularly top-down stepwise refinement) [4,7,17] and a data flow view of parallel processing [1,8,11] have been with us now for many years, no attempt has been made to unite the two fields: This paper describes an experiment that unites the two areas in both a textual and a graphical framework. Two packages are described. One produces a Cajole program [13] from input consisting of high-level function definitions together with refinements; and the other produces machine code for a data flow machine from a two dimensional graphical description of a programming problem. An example of each of the systems is given.

During a prospective study of 8 months duration conducted in the Department of Internal Medicine and the Department of Pulmonary Diseases of the Academic Medical Centre, Amsterdam, Gram stainings of sputa and urine were performed for all patients whose clinical symptoms indicated an acute urinary tract infection or pulmonary infection. On the test request, the physician reported which antibiotic treatment he would prescribe if a microscopic examination was not available. The results of the Gram stain were discussed by the microbiologist with the physician, and the antibiotic therapy recommended by the microbiologist was recorded. This recommendation was compared with the antibiotic prescription noted in the patient record 1 day later. Two days after the results of final cultures and susceptibility tests became available, the patient record was again investigated for changes in the antibiotic regimen. Of 57 urine samples and 103 sputa, 27 and 85, respectively, were derived from patients with an infection of the urinary tract or respiratory tract. The results of the Gram stain confirmed the physician's suspicion 91% of the time for urinary tract infections and 81% of the time for pulmonary infections. In 67% of the patients with suspected lower respiratory tract infections and in 58% of patients with suspected urinary tract infections, the antibiotic treatment recommended on the basis of the results of the Gram stain differed significantly from the antibiotic treatment that the physician would have prescribed had a microscopic examination not been performed. The microbiologist's advice on antibiotic treatment was followed in 79% of the cases of respiratory tract infection and in 65% of the cases of urinary tract infection. The antibiotic treatment was adjusted to the final results of culture and antimicrobial susceptibility testing in 54% of the urinary tract infections and in 31% of the respiratory tract infections. The results indicate that the examination of sputa and urine in patients suspected to have an infection of the respiratory tract or urinary tract influences the antibiotic choice considerably.