Klebsiella pneumoniae is an important gram-negative opportunistic pathogen causing primarily urinary tract infections, respiratory infections, and bacteraemia. The ability of bacteria to form ...biofilms on medical devices, e.g. catheters, has a major role in development of many nosocomial infections. Most clinical K. pneumoniae isolates express two types of fimbrial adhesins, type 1 fimbriae and type 3 fimbriae. In this study, we characterized the role of type 1 and type 3 fimbriae in K. pneumoniae biofilm formation.
Isogenic fimbriae mutants of the clinical K. pneumoniae isolate C3091 were constructed, and their ability to form biofilm was investigated in a flow cell system by confocal scanning laser microscopy. The wild type strain was found to form characteristic biofilm and development of K. pneumoniae biofilm occurred primarily by clonal growth, not by recruitment of planktonic cells. Type 1 fimbriae did not influence biofilm formation and the expression of type 1 fimbriae was found to be down-regulated in biofilm forming cells. In contrast, expression of type 3 fimbriae was found to strongly promote biofilm formation.
By use of well defined isogenic mutants we found that type 3 fimbriae, but not type 1 fimbriae, strongly promote biofilm formation in K. pneumoniae C3091. As the vast majority of clinical K. pneumoniae isolates express type 3 fimbriae, this fimbrial adhesin may play a significant role in development of catheter associated K. pneumoniae infections.
Pneumococcal disease is a leading cause of morbidity and mortality worldwide. The aim of this study was to investigate the association between specific pneumococcal serotypes and mortality from ...invasive pneumococcal disease (IPD).
In a nationwide population-based cohort study of IPD in Denmark during 1977-2007, 30-d mortality associated with pneumococcal serotypes was examined by multivariate logistic regression analysis after controlling for potential confounders. A total of 18,858 IPD patients were included. Overall 30-d mortality was 18%, and 3% in children younger than age 5 y. Age, male sex, meningitis, high comorbidity level, alcoholism, and early decade of diagnosis were significantly associated with mortality. Among individuals aged 5 y and older, serotypes 31, 11A, 35F, 17F, 3, 16F, 19F, 15B, and 10A were associated with highly increased mortality as compared with serotype 1 (all: adjusted odds ratio >or=3, p<0.001). In children younger than 5 y, associations between serotypes and mortality were different than in adults but statistical precision was limited because of low overall childhood-related mortality.
Specific pneumococcal serotypes strongly and independently affect IPD associated mortality.
Bacteriophages constitute an important part of the human gut microbiota, but their impact on this community is largely unknown. Here, we cultivate temperate phages produced by 900 E. coli strains ...isolated from 648 fecal samples from 1-year-old children and obtain coliphages directly from the viral fraction of the same fecal samples. We find that 63% of strains hosted phages, while 24% of the viromes contain phages targeting E. coli. 150 of these phages, half recovered from strain supernatants, half from virome (73% temperate and 27% virulent) were tested for their host range on 75 E. coli strains isolated from the same cohort. Temperate phages barely infected the gut strains, whereas virulent phages killed up to 68% of them. We conclude that in fecal samples from children, temperate coliphages dominate, while virulent ones have greater infectivity and broader host range, likely playing a role in gut microbiota dynamics.
Cesarean section changes neonatal gut colonization Stokholm, Jakob, MD, PhD; Thorsen, Jonathan, MD; Chawes, Bo L., MD, PhD ...
Journal of allergy and clinical immunology,
09/2016, Letnik:
138, Številka:
3
Journal Article
Recenzirano
Odprti dostop
Background Delivery by means of cesarean section has been associated with increased risk of childhood immune-mediated diseases, suggesting a role of early bacterial colonization patterns for immune ...maturation. Objective We sought to describe the influence of delivery method on gut and airway colonization patterns in the first year of life in the Copenhagen Prospective Studies on Asthma in Childhood2010 (COPSAC2010 ) birth cohort. Methods Seven hundred children from the COPSAC2010 birth cohort participated in this analysis. Fecal samples were collected at age 1 week, 1 month, and 1 year, and hypopharyngeal aspirates were collected at age 1 week, 1 month, and 3 months and cultured for bacteria. Detailed information on delivery method, intrapartum antibiotics, and lifestyle factors was obtained by personal interviews. Results Seventy-eight percent of the children were born by means of natural delivery, 12% by means of emergency cesarean section, and 9% by means of elective cesarean section. Birth by means of cesarean section was significantly associated with colonization of the intestinal tract by Citrobacter freundii , Clostridium species, Enterobacter cloacae , Enterococcus faecalis , Klebsiella oxytoca , Klebsiella pneumoniae , and Staphylococcus aureus at age 1 week, whereas colonization by Escherichia coli was associated with natural birth. At age 1 month, these differences were less prominent, and at age 1 year, they were not apparent, which was confirmed by means of multivariate data-driven partial least squares analyses. The initial airway microbiota was unaffected by birth method. Conclusion Delivery by means of cesarean section was associated with early colonization patterns of the neonatal gut but not of the airways. The differences normalized within the first year of life. We speculate that microbial derangements, as indicated in our study, can demonstrate a possible link between delivery by means of cesarean section and immune-mediated disease.
ABSTRACT
Since the outbreak of COVID-19, the world has raced to understand and accurately diagnose infection caused by SARS-CoV-2. Today, hundreds of commercial antibody tests are on the market ...despite often lacking proper validation and with unsatisfactory sensitivity and/or specificity. In addition, many questions related to the humoral response remain unresolved, although research is carried out at an unprecedented speed. Despite the shortcomings, serological assays have an important part to play in combating the pandemic by aiding in diagnosis and sero-epidemiological studies. However, careful attention must be paid to the application of serology and the interpretation of serological data—especially in low prevalence regions, both at an individual and at a population level. In this article, we argue that serological results are often misinterpreted, and in the eagerness to be first, methodological rigor is often taking a backseat.
Antibody testing for SARS-CoV-2 is widespread despite poor test validation and limited knowledge on antibody responses, which makes it crucial to understand both the potential, limitations and interpretation of serology.
Highly invasive, community-acquired Klebsiella pneumoniae infections have recently emerged, resulting in pyogenic liver abscesses. These infections are caused by hypervirulent K. pneumoniae (hvKP) ...isolates primarily of capsule serotype K1 or K2. Hypervirulent K1 isolates belong to clonal complex 23 (CC23), indicating that this clonal lineage has a specific genetic background conferring hypervirulence. Here, we apply whole-genome sequencing to a collection of K. pneumoniae isolates to characterize the phylogenetic background of hvKP isolates with an emphasis on CC23. Most of the hvKP isolates belonged to CC23 and grouped into a distinct monophyletic clade, revealing that CC23 is a unique clonal lineage, clearly distinct from nonhypervirulent strains. Separate phylogenetic analyses of the CC23 isolates indicated that the CC23 lineage evolved recently by clonal expansion from a single common ancestor. Limited grouping according to geographical origin was observed, suggesting that CC23 has spread globally through multiple international transmissions. Conversely, hypervirulent K2 strains clustered in genetically unrelated groups. Strikingly, homologues of a large virulence plasmid were detected in all hvKP clonal lineages, indicating a key role in K. pneumoniae hypervirulence. The plasmid encodes two siderophores, aerobactin and salmochelin, and RmpA (regulator of the mucoid phenotype); all these factors were found to be restricted to hvKP isolates. Genomic comparisons revealed additional factors specifically associated with CC23. These included a distinct variant of a genomic island encoding yersiniabactin, colibactin, and microcin E492. Furthermore, additional novel genomic regions unique to CC23 were revealed which may also be involved in the increased virulence of this important clonal lineage.
During the last 3 decades, hypervirulent Klebsiella pneumoniae (hvKP) isolates have emerged, causing severe community-acquired infections primarily in the form of pyogenic liver abscesses. This syndrome has so far primarily been found in Southeast Asia, but increasing numbers of cases are being reported worldwide, indicating that the syndrome is turning into a globally emerging disease. We applied whole-genome sequencing to a collection of K. pneumoniae clinical isolates to reveal the phylogenetic background of hvKP and to identify genetic factors associated with the increased virulence. The hvKP isolates primarily belonged to clonal complex 23 (CC23), and this clonal lineage was revealed to be clearly distinct from nonhypervirulent strains. A specific virulence plasmid was found to be associated with hypervirulence, and novel genetic determinants uniquely associated with CC23 were identified. Our findings extend the understanding of the genetic background of the emergence of hvKP clones.
The degree to which molecular epidemiology reveals information about the sources and transmission patterns of an outbreak depends on the resolution of the technology used and the samples studied. ...Isolates of Escherichia coli O104:H4 from the outbreak centered in Germany in May–July 2011, and the much smaller outbreak in southwest France in June 2011, were indistinguishable by standard tests. We report a molecular epidemiological analysis using multiplatform whole-genome sequencing and analysis of multiple isolates from the German and French outbreaks. Isolates from the German outbreak showed remarkably little diversity, with only two single nucleotide polymorphisms (SNPs) found in isolates from four individuals. Surprisingly, we found much greater diversity (19 SNPs) in isolates from seven individuals infected in the French outbreak. The German isolates form a clade within the more diverse French outbreak strains. Moreover, five isolates derived from a single infected individual from the French outbreak had extremely limited diversity. The striking difference in diversity between the German and French outbreak samples is consistent with several hypotheses, including a bottleneck that purged diversity in the German isolates, variation in mutation rates in the two E. coli outbreak populations, or uneven distribution of diversity in the seed populations that led to each outbreak.
•Common colds are primarily caused by rhinoviruses (RV).•Prevention of RV infections has enormous health and economic potential.•The major transmission route in many indoor settings is through the ...air.•Preventive measures should focus on reducing aerosol generation and concentration.•Hands may also contribute to the transmission of RV in some workplaces.
Human rhinoviruses (RVs) are the most common cause of acute respiratory tract illness and upper respiratory tract infections, traditionally defined as ‘common colds’. Experimental transmission of RV has been studied for more than 50 years. However, there are divergent results as to whether hands and fomites or aerosols constitute the dominant route of transmission in natural settings.
We have systematically reviewed the literature according to the PRISMA 2020 statement. Searches were run in PubMed and Web of Science until August 2022. Inclusion criteria were original studies of relevance for revealing the route of transmission of rhinovirus in humans.
The search yielded 663 results, and 25 studies met the inclusion criteria and were selected for this review. These articles addressing RV transmission routes were assigned to 1 of 3 groups: (1) indirect transmission by fomites and hands, (2) direct transmission via large aerosols (droplets) or small aerosols, or (3) transmission either direct via large aerosols (droplets) or small aerosols and fomite or hands.
We found low evidence, that transmission via hands and fomite followed by self-inoculation is the dominant transmission route in real-life indoor settings. We found moderate evidence, that airborne transmission either via large aerosols or small aerosols is the major transmission route of rhinovirus transmission in real-life indoor settings. This suggests that the major transmission route of RVs in many indoor settings is through the air (airborne transmission).
The spatial organization of Pseudomonas aeruginosa and Staphylococcus aureus in chronic wounds was investigated in the present study. Wound biopsy specimens were obtained from patients diagnosed as ...having chronic venous leg ulcers, and bacterial aggregates in these wounds were detected and located by the use of peptide nucleic acid-based fluorescence in situ hybridization and confocal laser scanning microscopy (CLSM). We acquired CLSM images of multiple regions in multiple sections cut from five wounds containing P. aeruginosa and five wounds containing S. aureus and measured the distance of the bacterial aggregates to the wound surface. The distance of the P. aeruginosa aggregates to the wound surface was significantly greater than that of the S. aureus aggregates, suggesting that the distribution of the bacteria in the chronic wounds was nonrandom. The results are discussed in relation to our recent finding that swab culturing techniques may underestimate the presence of P. aeruginosa in chronic wounds and in relation to the hypothesis that P. aeruginosa bacteria located in the deeper regions of chronic wounds may play an important role in keeping the wounds arrested in a stage dominated by inflammatory processes.
Antibiotic treatment during pregnancy and birth is very common. In this study, we describe the estimated prevalence of antibiotic administration during pregnancy and birth in the COPSAC2010 pregnancy ...cohort, and analyze dependence on social and lifestyle-related factors.
706 pregnant women from the novel unselected Copenhagen Prospective Study on Asthma in Childhood (COPSAC2010) pregnancy cohort participated in this analysis. Detailed information on oral antibiotic prescriptions during pregnancy filled at the pharmacy was obtained and verified longitudinally. Information on intrapartum antibiotics, social, and lifestyle-factors was obtained by personal interviews.
The prevalence of antibiotic use was 37% during pregnancy and 33% intrapartum. Lower maternal age at birth; adjusted odds ratio (aOR) 0.94, 95% CI, 0.90-0.98, p = 0.003 and maternal smoking; aOR 1.97, 95% CI, 1.07-3.63, p = 0.030 were associated with use of antibiotics for urinary tract infection during pregnancy. Maternal educational level (low vs. high), aOR 2.32, 95% CI, 1.24-4.35, p = 0.011, maternal asthma; aOR 1.99, 95% CI, 1.33-2.98, p < 0.001 and previous childbirth; aOR 1.80, 95% CI, 1.21-2.66, p = 0.004 were associated with use of antibiotics for respiratory tract infection during pregnancy. Lower gestational age; aOR 0.72, 95% CI, 0.61-0.85, p < 0.001, maternal smoking; aOR 2.84, 95% CI, 1.33-6.06, p = 0.007, and nulliparity; aOR 1.79, 95% CI, 1.06-3.02, p = 0.030 were associated with administration of intrapartum antibiotics in women giving birth vaginally.
Antibiotic administration during pregnancy and birth may be influenced by social and lifestyle-factors. Understanding such risk factors may guide preventive strategies in order to avoid unnecessary use of antibiotics.
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