Влияние антропогенных нагрузок на энергетические запасы мидий Mytilus galloprovincialis Lam.

Дослiджено вмiст глiкогену та сумарних лiпiдiв у мiдiй Mytilus galloprovincialis Lam. з двох станцiй Одеської затоки з рiзним антропогенним навантаженням. Встановлено, що поблизу випуску очисних споруд вмiст глiкогену в гонадах молюскiв в 1,7, в гепатопанкреасi в 1,4 та в зябрах в 1,9 раза менший, нiж у районi м. Великий Фонтан. У районi випуску очисних споруд вмiст сумарних лiпiдiв у гепатопанкреасi мiдiй в 1,5 раза нижчий, нiж у районi м. Великий Фонтан. Рiзницi у вмiстi сумарних лiпiдiв у гонадах та зябрах мiдiй не виявлено.The glycogen and lipids contents in mussels (Mytilus galloprovincialis Lam.) are studied on two stations in the Odessa Bay (Ukraine) under the influence of different anthropogenic loads. It has been established that, near the water treatment plant, the glycogen content in mussels in gonads was 1.7, in the hepatopancreas 1.4 and in the gills — 1.9 times less than that in the relatively clean area near the Cape Bolshoi Fontan. For lipids, it was 1.5 times less in hepatopancreas near the water treatment plant. No difference was noted for the lipids in mussel gonads and gills

The Carriage of Multiresistant Bacteria after Travel (COMBAT) prospective cohort study: Methodology and design

Background: Antimicrobial resistance (AMR) is one of the major threats to public health around the world. Besides the intense use and misuse of antimicrobial agents as the major force behind the increase in antimicrobial resistance, the e

Prevalence and risk factors for carriage of ESBL-producing Enterobacteriaceae in a population of Dutch travellers: A cross-sectional study

Background: We investigated prevalence and predictive factors for ESBL-E carriage in a population of mostly travellers prior to their travel (n = 2216). In addition, we examined ESBL genotype before travel and compared these to returning travellers. Method: A questionnaire and faecal sample were collected before travel, and a second faecal sample was collected immediately after travel. Faecal samples were analysed for ESBL-E, with genotypic characterization by PCR and sequencing. Risk factors for ESBL-E carriage prior to travel were identified by logistic regression analyses. Results: Before travel, 136 participants (6.1%) were colonized with ESBL-E. Antibiotic use in the past three months (ORadjusted 2.57; 95% CI 1.59–4.16) and travel outside of Europe in the past year (1.92, 1.28–2.87) were risk factors for ESBL-E colonisation prior to travel. Travel outside of Europe carried the largest attributable risk (39.8%). Prior to travel 31.3% (40/128) of participants carried blaCTX-M 15 and 21.9% (28/128) blaCTX-M 14/18. In returning travellers 633 acquired ESBL-E of who 53.4% (338/633) acquired blaCTX-M 15 and 17.7% (112/633) blaCTX-M 14/18. Conclusion: In our population of Dutch travellers we found a pre-travel ESBL-E prevalence of 6.1%. Prior to travel, previous antibiotic use and travel outside of Europe were the strongest independent predictors

Carriage of Blastocystis spp. in travellers - A prospective longitudinal study

Introduction: A lack of prospective and longitudinal data on pre- and post-travel carriage of Blastocystis spp. complicates interpretation of a positive test post-travel. Therefore we studied dynamics of Blastocystis carriage in a cohort of Dutch travellers. Methods: From the prospective, multicentre COMBAT study among 2001 Dutch travellers, a subset of 491 travellers was selected based on travel destination to 7 subregions (70 or 71 travellers each). Faecal samples taken directly before and after travel were screened for Blastocystis with qPCR, followed, when positive, by sequence analysis to determine subtypes. Results: After exclusion of 12 samples with missing samples or inhibited qPCR-reactions, stool samples of 479 travellers were analysed. Before travel, 174 of them (36.3%) carried Blastocystis and in most of these, the same subtype was persistently carried. However, in 48/174 of those travellers (27.6%; CI95 20.8–36.6%) no Blastocystis or a different subtype was detected in the post-travel sample, indicating loss of Blastocystis during travel. Only 26 (5.4%; CI95 3.7%–8.0%) of all travellers acquired Blastocystis, including two individuals that were already positive for Blastocystis before travel but acquired a different subtype during travel. Discussion: This study shows that Blastocystis carriage in travellers is highly dynamic. The observed acquisition and loss of Blastocystis could either be travel-related or reflect the natural course of Blastocystis carriage. We demonstrate that the majority of Blastocystis detected in post-travel samples were already carried before travel

Global phylogenetic analysis of Escherichia coli and plasmids carrying the mcr-1 gene indicates bacterial diversity but plasmid restriction

To understand the dynamics behind the worldwide spread of the mcr-1 gene, we determined the population structure of Escherichia coli and of mobile genetic elements (MGEs) carrying the mcr-1 gene. After a systematic review of the literature we included 65 E. coli whole genome sequences (WGS), adding 6 recently sequenced travel related isolates, and 312 MLST profiles. We included 219 MGEs described in 7 Enterobacteriaceae species isolated from human, animal and environmental samples. Despite a high overall diversity, 2 lineages were observed in the E. coli population that may function as reservoirs of the mcr-1 gene, the largest of which was linked to ST10, a sequence type known for its ubiquity in human faecal samples and in food samples. No genotypic clustering by geographical origin or isolation source was observed. Amongst a total of 13 plasmid incompatibility types, the IncI2, IncX4 and IncHI2 plasmids accounted for more than 90% of MGEs carrying the mcr-1 gene. We observed significant geographical clustering with regional spread of IncHI2 plasmids in Europe and IncI2 in Asia. These findings point towards promiscuous spread of the mcr-1 gene by efficient horizontal gene transfer dominated by a limited number of plasmid incompatibility types

Mathematical studies of the dynamics of antibiotic resistance

In Part I we discuss models for the spread of nosocomial antibioticresistant bacteria. We focus on pathogens for which re-admission of colonized individuals is important, i.e., the feedback-loop between the hospital and the extramural population. In Chapter 2 we will discuss an analytical model and in Chapter 3 we will focus on colonization with Methicillin-resistant Staphylococcus aureus (MRSA). We use both an analytical and a simulation model. Both models suggest that isolation of identified carriers of MRSA in hospitals combined with either screening on admission of high-risk patient or the screening of contact patients in case of the identification of an unexpected MRSA carrier in the hospital, may be sufficient to prevent high levels of MRSA in the hospitals. However, the so-called Dutch search and destroy policy in which both interventions are applied ensures that the current low prevalence level of MRSA in the Netherlands is far less sensitive to changes in the parameter values. In Part II we use real hospital data to draw conclusions for specific pathogens/diseases. In Chapter 4 we use a simple observation to disentangle the phenomena that patients who acquire an infection are likely to stay longer in a unit and that patients who stay longer in a unit are more likely to acquire an infection. In Chapter 5 we use likelihood methods in a Markov chain approach to distinguish between different infection routes on the basis of the fluctuations in the prevalence. This method is applied to data for colonization with two different pathogens. This method is also used to determine optimal culture frequencies

Successful Veterans Affairs initiative to prevent methicillin-resistant Staphylococcus aureus infections revisited

In 2011 Jain et al reported a 62% reduction of healthcare-associated methicillin-resistant Staphylococcus aureus infections that resulted from an intervention bundle. Here we present a mathematical model and prove, using parameters from the study by Jain et al, that the universal screen and isolate strategy can have contributed only marginally to the reduction in infections

Serial Intervals of Respiratory Infectious Diseases: A Systematic Review and Analysis

The serial interval of an infectious disease represents the duration between symptom onset of a primary case and symptom onset of its secondary cases. A good evidence base for such values is essential, because they allow investigators to identify epidemiologic links between cases and serve as an important parameter in epidemic transmission models used to design infection control strategies. We reviewed the literature for available data sets containing serial intervals and for reported values of serial intervals. We were able to collect data on outbreaks within households, which we reanalyzed to infer a mean serial interval using a common statistical method. We estimated the mean serial intervals for influenza A(H3N2) (2.2 days), pandemic influenza A(H1N1)pdm09 (2.8 days), respiratory syncytial virus (7.5 days), measles (11.7 days), varicella (14.0 days), smallpox (17.7 days), mumps (18.0 days), rubella (18.3 days), and pertussis (22.8 days). For varicella, we found an evidence-based value that deviates substantially from the 21 days commonly used in transmission models. This value of the serial interval for pertussis is, to the best of our knowledge, the first that is based on observations. Our review reveals that, for most infectious diseases, there is very limited evidence to support the serial intervals that are often cited

Successful Veterans Affairs initiative to prevent methicillin-resistant Staphylococcus aureus infections revisited

In 2011 Jain et al reported a 62% reduction of healthcare-associated methicillin-resistant Staphylococcus aureus infections that resulted from an intervention bundle. Here we present a mathematical model and prove, using parameters from the study by Jain et al, that the universal screen and isolate strategy can have contributed only marginally to the reduction in infections

Transmissibility of Livestock-associated Methicillin-Resistant Staphylococcus aureus

Previous findings have suggested that the nosocomial transmission capacity of livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) is lower than that of other MRSA genotypes. We therefore performed a 6-month (June 1–November 30, 2011) nationwide study to quantify the single-admission reproduction number, RA, for LA-MRSA in 62 hospitals in the Netherlands and to compare this transmission capacity to previous estimates. We used spa typing for genotyping. Quantification of RA was based on a mathematical model incorporating outbreak sizes, detection rates, and length of hospital stay. There were 141 index cases, 40 (28%) of which were LA-MRSA. Contact screening of 2,101 patients and 7,260 health care workers identified 18 outbreaks (2 LA-MRSA) and 47 secondary cases (3 LA-MRSA). RA values indicated that transmissibility of LA-MRSA is 4.4 times lower than that of other MRSA (not associated with livestock)