Stephan Stenmark

Distinct roles of reactive nitrogen and oxygen species to control infection with the facultative intracellular bacterium Francisella tularensis.

ABSTRACT Reactive nitrogen species (RNS) and reactive oxygen species (ROS) are important mediators of the bactericidal host response. We investigated the contribution of these two mediators to the control of infection with the facultative intracellular bacterium Francisella tularensis. When intradermally infected with the live vaccine strain F. tularensis LVS, mice deficient in production of RNS (iNOS−/− mice) or in production of ROS by the phagocyte oxidase (p47phox−/− mice) showed compromised resistance to infection. The 50% lethal dose (LD50) for iNOS−/− mice was <20 CFU, and the LD50 for p47phox−/− mice was 4,400 CFU, compared to an LD50 of >500,000 CFU for wild-type mice. The iNOS−/− mice survived for 26.4 ± 1.8 days, and the p47phox−/− mice survived for 10.1 ± 1.3 days. During the course of infection, the serum levels of gamma interferon (IFN-γ) and interleukin-6 were higher in iNOS−/− and p47phox−/− mice than in wild-type mice. Histological examination of livers of iNOS−/− mice revealed severe liver pathology. Splenocytes obtained 5 weeks after primary infection from antibiotic-treated iNOS−/− mice showed an in vitro recall response that was similar in magnitude and greater secretion of IFN-γ compared to cells obtained from wild-type mice. In summary, mice lacking expression of RNS or ROS showed extreme susceptibility to infection with F. tularensis LVS. The roles of RNS and ROS seemed to be distinct since mice deficient in production of ROS showed dissemination of infection and died during the early phase of infection, whereas RNS deficiency led to severe liver pathology and a contracted course of infection.

Specific antibodies contribute to the host protection against strains of Francisella tularensis subspecies holarctica.

T cells are crucial to the control and eradication of the facultative intracellular bacterium Francisella tularensis. A contributory role of humoral antibodies in the host defence remains to be assessed. We used B-cell-deficient mice to study the possible contribution of antibodies to the defence against the live vaccine strain (LVS) or a clinical isolate of F. tularensis, both belonging to the subspecies holarctica (type B). When B-cell-deficient (Igmu(-/-)) mice of the C57BL/10 background were administered immune serum one day before intradermal injection of LVS, they developed lower bacterial numbers in skin, liver, and spleen than did mice receiving normal serum, and survived a challenge inoculum that was lethal for mice given normal serum. Administration of immune serum to C57BL/10 mice afforded protection also against infection with the clinical isolate of F. tularensis subsp. holarctica. Five days after intradermal inoculation of bacteria of the isolate, animals receiving immune serum showed 4log10 lower bacterial counts in liver and spleen than mice administered normal serum. In mice primed by LVS infection, T-cell immunity and host protection were strong and only a marginal contribution of immune serum against a secondary intradermal infection was demonstrated. Together, these findings show that specific antibodies contribute to the host defence of mice against F. tularensis subsp. holarctica.

Daclatasvir combined with sofosbuvir or simeprevir in liver transplant recipients with severe recurrent hepatitis C infection

Daclatasvir (DCV) is a potent, pangenotypic nonstructural protein 5A inhibitor with demonstrated antiviral efficacy when combined with sofosbuvir (SOF) or simeprevir (SMV) with or without ribavirin (RBV) in patients with chronic hepatitis C virus (HCV) infection. Herein, we report efficacy and safety data for DCV‐based all‐oral antiviral therapy in liver transplantation (LT) recipients with severe recurrent HCV. DCV at 60 mg/day was administered for up to 24 weeks as part of a compassionate use protocol. The study included 97 LT recipients with a mean age of 59.3 ± 8.2 years; 93% had genotype 1 HCV and 31% had biopsy‐proven cirrhosis between the time of LT and the initiation of DCV. The mean Model for End‐Stage Liver Disease (MELD) score was 13.0 ± 6.0, and the proportion with Child‐Turcotte‐Pugh (CTP) A/B/C was 51%/31%/12%, respectively. Mean HCV RNA at DCV initiation was 14.3 × 6 log10 IU/mL, and 37% had severe cholestatic HCV infection. Antiviral regimens were selected by the local investigator and included DCV+SOF (n = 77), DCV+SMV (n = 18), and DCV+SMV+SOF (n = 2); 35% overall received RBV. At the end of treatment (EOT) and 12 weeks after EOT, 88 (91%) and 84 (87%) patients, respectively, were HCV RNA negative or had levels <43 IU/mL. CTP and MELD scores significantly improved between DCV‐based treatment initiation and last contact. Three virological breakthroughs and 2 relapses occurred in patients treated with DCV+SMV with or without RBV. None of the 8 patient deaths (6 during and 2 after therapy) were attributed to therapy. In conclusion, DCV‐based all‐oral antiviral therapy was well tolerated and resulted in a high sustained virological response in LT recipients with severe recurrent HCV infection. Most treated patients experienced stabilization or improvement in their clinical status. Liver Transplantation 22 446‐458 2016 AASLD

Syndromic surveillance for local outbreak detection and awareness : evaluating outbreak signals of acute gastroenteritis in telephone triage, web-based queries and over-the-counter pharmacy sales

SUMMARY For the purpose of developing a national system for outbreak surveillance, local outbreak signals were compared in three sources of syndromic data – telephone triage of acute gastroenteritis, web queries about symptoms of gastrointestinal illness, and over-the-counter (OTC) pharmacy sales of antidiarrhoeal medication. The data sources were compared against nine known waterborne and foodborne outbreaks in Sweden in 2007–2011. Outbreak signals were identified for the four largest outbreaks in the telephone triage data and the two largest outbreaks in the data on OTC sales of antidiarrhoeal medication. No signals could be identified in the data on web queries. The signal magnitude for the fourth largest outbreak indicated a tenfold larger outbreak than officially reported, supporting the use of telephone triage data for situational awareness. For the two largest outbreaks, telephone triage data on adult diarrhoea provided outbreak signals at an early stage, weeks and months in advance, respectively, potentially serving the purpose of early event detection. In conclusion, telephone triage data provided the most promising source for surveillance of point-source outbreaks.

Susceptibility to infections, without concomitant hyper-IgE, reported in 1976, is caused by hypomorphic mutation in the phosphoglucomutase 3 (PGM3) gene.

Phosphoglucomutase 3 (PGM3) is an enzyme converting N-acetyl-glucosamine-6-phosphate to N-acetyl-glucosamine-1-phosphate, a precursor important for glycosylation. Mutations in the PGM3 gene have recently been identified as the cause of novel primary immunodeficiency with a hyper-IgE like syndrome. Here we report the occurrence of a homozygous mutation in the PGM3 gene in a family with immunodeficient children, described already in 1976. DNA from two of the immunodeficient siblings was sequenced and shown to encode the same homozygous missense mutation, causing a destabilized protein with reduced enzymatic capacity. Affected individuals were highly prone to infections, but lack the developmental defects in the nervous and skeletal systems, reported in other families. Moreover, normal IgE levels were found. Thus, belonging to the expanding group of congenital glycosylation defects, PGM3 deficiency is characterized by immunodeficiency, with or without increased IgE levels, and with variable forms of developmental defects affecting other organ systems.

Risk factors and potential preventive measures for nephropatia epidemica in Sweden 2011–2012: a case–control study

Introduction Nephropatia epidemica (NE), a relatively mild form of hemorrhagic fever with renal syndrome caused by the Puumala virus (PUUV), is endemic in northern Sweden. We aim to study the risk factors associated with NE in this region. Methods We conducted a matched case–control study between June 2011 and July 2012. We compared confirmed NE cases with randomly selected controls, matched by age, sex, and place of infection or residence. We analyzed the association between NE and several occupational, environmental, and behavioral exposures using conditional logistic regression. Results We included in the final analysis 114 cases and 300 controls, forming 246 case–control pairs. Living in a house with an open space beneath, making house repairs, living less than 50 m from the forest, seeing rodents, and smoking were significantly associated with NE. Conclusion Our results could orient public health policies targeting these risk factors and subsequently reduce the NE burden in the region.

Randomized Trial Evaluating the Impact of Ribavirin Mono-Therapy and Double Dosing on Viral Kinetics, Ribavirin Pharmacokinetics and Anemia in Hepatitis C Virus Genotype 1 Infection

In this pilot study (RibaC), 58 hepatitis C virus (HCV) genotype 1 infected treatment-naïve patients were randomized to (i) 2 weeks ribavirin double dosing concomitant with pegylated interferon-α (pegIFN-α), (ii) 4 weeks ribavirin mono-therapy prior to adding pegIFN-α, or (iii) standard-of-care (SOC) ribavirin dosing concurrent with pegIFN-α. Four weeks of ribavirin mono-therapy resulted in a mean 0.46 log10 IU/mL HCV RNA reduction differentially regulated across IL28B genotypes (0.89 vs. 0.21 log10 IU/mL for CC and CT/TT respectively; P = 0.006), increased likelihood of undetectable HCV RNA week 4 after initiating pegIFN-α and thus shortened treatment duration (P<0.05), and decreased median IP-10 concentration from 550 to 345 pg/mL (P<0.001). Both experimental strategies impacted on ribavirin concentrations, and high levels were achieved after one week of double dosing. However, by day 14, double dosing entailed a greater hemoglobin decline as compared to SOC (2.2 vs. 1.4 g/dL; P = 0.03). Conclusion: Ribavirin down-regulates IP-10, and may have an anti-viral effect differently regulated across IL28B genotypes. Trial Registration ClinicalTrials.gov NCT01226771

Early outbreak detection by linking health advice line calls to water distribution areas retrospectively demonstrated in a large waterborne outbreak of cryptosporidiosis in Sweden

BackgroundIn the winter and spring of 2011 a large outbreak of cryptosporidiosis occurred in Skellefteå municipality, Sweden. This study summarizes the outbreak investigation in terms of outbreak size, duration, clinical characteristics, possible source(s) and the potential for earlier detection using calls to a health advice line.MethodsThe investigation included two epidemiological questionnaires and microbial analysis of samples from patients, water and other environmental sources. In addition, a retrospective study based on phone calls to a health advice line was performed by comparing patterns of phone calls between different water distribution areas.ResultsOur analyses showed that approximately 18,500 individuals were affected by a waterborne outbreak of cryptosporidiosis in Skellefteå in 2011. This makes it the second largest outbreak of cryptosporidiosis in Europe to date. Cryptosporidium hominis oocysts of subtype IbA10G2 were found in patient and sewage samples, but not in raw water or in drinking water, and the initial contamination source could not be determined. The outbreak went unnoticed to authorities for several months. The analysis of the calls to the health advice line provides strong indications early in the outbreak that it was linked to a particular water treatment plant.ConclusionsWe conclude that an earlier detection of the outbreak by linking calls to a health advice line to water distribution areas could have limited the outbreak substantially.

Antibiotic prescription and clinical management of common infections among general practitioners in Latvia, Lithuania, and Sweden: a pilot survey with a simple protocol

Comparative information on diagnosis-related antibiotic prescribing patterns are scarce from primary care within and between countries. To describe and compare antibiotic prescription and routine management of infections in primary care in Latvia (LV), Lithuania (LT) and two study sites in Sweden (SE), a cross-sectional observational study on patients who consulted due to sypmtoms compatible with infection was undetraken. Infection and treatment was detected and recorded by physicians only. Data was collected from altogether 8786 consecutive patients with infections in the three countries. Although the overall proportion of patients receiving an antibiotic prescription was similar in all three countries (LV and LT 42%, SE 38%), there were differences in the rate of prescription between the countries depending on the respective diagnoses. While penicillins dominated among prescriptions (LV 58%, LT 67%, SE 70%), phenoxymethylpenicillin was most commonly prescribed in Sweden (57% of all penicillins), while it was amoxicillin with or without clavulanic acid in Latvia (99%) and Lithuania (85%) respectively. Pivmecillinam and flucloxacillin, which accounted for 29% of penicillins in Sweden, were available neither in Latvia nor in Lithuania. The applied methodology was simple, and provided useful information on differences in treatment of common infections in ambulatory care in the absence of available computerized diagnosis–prescription data. Despite some limitations, the method can be used for assessment of intention to treat and compliance to treatment guidelines and benchmarking locally, nationally, or internationally, just as the point prevalence surveys (PPS) protocols have been used in hospitals all over Europe.