BACKGROUND A large outbreak of diarrhea and the hemolytic–uremic syndrome caused by an unusual serotype of Shiga-toxin–producing Escherichia coli (O104:H4) began in Germany in May 2011. As of July 22, a large number of cases of diarrhea caused by Shiga-toxin–producing E. coli have been reported — 3167 without the hemolytic–uremic syndrome (16 deaths) and 908 with the hemolytic–uremic syndrome (34 deaths) — indicating that this strain is notably more virulent than most of the Shiga-toxin–producing E. coli strains. Preliminary genetic characterization of the outbreak strain suggested that, unlike most of these strains, it should be classified within the enteroaggregative pathotype of E. coli. METHODS We used third-generation, single-molecule, real-time DNA sequencing to determine the complete genome sequence of the German outbreak strain, as well as the genome sequences of seven diarrhea-associated enteroaggregative E. coli serotype O104:H4 strains from Africa and four enteroaggregative E. coli reference strains belonging to other serotypes. Genomewide comparisons were performed with the use of these enteroaggregative E. coli genomes, as well as those of 40 previously sequenced E. coli isolates. RESULTS The enteroaggregative E. coli O104:H4 strains are closely related and form a distinct clade among E. coli and enteroaggregative E. coli strains. However, the genome of the German outbreak strain can be distinguished from those of other O104:H4 strains because it contains a prophage encoding Shiga toxin 2 and a distinct set of additional virulence and antibiotic-resistance factors. CONCLUSIONS Our findings suggest that horizontal genetic exchange allowed for the emergence of the highly virulent Shiga-toxin–producing enteroaggregative E. coli O104:H4 strain that caused the German outbreak. More broadly, these findings highlight the way in which the plasticity of bacterial genomes facilitates the emergence of new pathogens.

The present paper presents a hypothesis aimed at explaining why venous leg ulcers, pressure ulcers, and diabetic foot ulcers develop into a chronic state. We propose that the lack of proper wound healing is at least in part caused by inefficient eradication of infecting, opportunistic pathogens, a situation reminiscent of chronic Pseudomonas aeruginosa infections found in patients suffering from cystic fibrosis (CF). We have analyzed sections from chronic wounds by fluorescence in situ hybridization and found distinct microcolonies--the basal structures of bacterial biofilms. Several researchers have previously reported that another important hallmark of biofilm formation is development of increased tolerance to various antimicrobial measures and treatments. Furthermore, the immune response to infecting bacteria in the cystic fibrosis lung is dominated by polymorphonuclear neutrophils (PMNs), and we have recently shown that in vitro biofilms of P. aeruginosa produce a shielding mechanism that offers protection from the phagocytic activity of PMNs. We hypothesize that the presence of P. aeruginosa in biofilms, and the lack of concomitant elimination by attended PMNs, are the main causes of inefficient eradication by antibiotic treatment and antimicrobial activity of the innate immune system, respectively.

The aim of the study was to investigate the bacterial profile of chronic venous leg ulcers and the importance of the profile to ulcer development. Patients with persisting venous leg ulcers were included and followed for 8 weeks. Every second week, ulcer samples were collected and the bacterial species present were identified. More than one bacterial species were detected in all the ulcers. The most common bacteria found were Staphylococcus aureus (found in 93.5% of the ulcers), Enterococcus faecalis (71.7%), Pseudomonas aeruginosa (52.2%), coagulase-negative staphylococci (45.7%), Proteus species (41.3%) and anaerobic bacteria (39.1%). Resident bacterial species were present in all the ulcers. In 76% of the ulcers, two or more (up to five) resident bacterial species were found. The most common resident bacterial species were S. aureus and P. aeruginosa. Furthermore, ulcers with P. aeruginosa were found to be significantly larger than ulcers without the presence of P. aeruginosa (P < 0.005). Our study demonstrated that the chronic wound is colonised by multiple bacterial species and that once they are established many of them persist in the wound. Our results suggest that the presence of P. aeruginosa in venous leg ulcers can induce ulcer enlargement and/or cause delayed healing.

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Due to urgency and demand, numerous severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) immunoassays are rapidly being developed and placed on the market with limited validation on clinical samples. Thorough validation of serological tests are required to facilitate their use in the accurate diagnosis of SARS-CoV-2 infection, confirmation of molecular results, contact tracing, and epidemiological studies. This study evaluated the sensitivity and specificity of nine commercially available serological tests. These included three enzyme-linked immunosorbent assays (ELISAs) and six point-of-care (POC) lateral flow tests. The assays were validated using serum samples from: i) SARS-CoV-2 PCR-positive patients with a documented first day of disease; ii) archived sera obtained from healthy individuals before the emergence of SARS-CoV-2 in China;iii) sera from patients with acute viral respiratory tract infections caused by other coronaviruses or noncoronaviruses; and iv) sera from patients positive for dengue virus, cytomegalovirus and Epstein Barr virus.The results showed 100% specificity for the Wantai SARS-CoV-2 Total Antibody ELISA, 93% for the Euroimmun IgA ELISA, and 96% for the Euroimmun IgG ELISA with sensitivities of 90%, 90%, and 65%, respectively. The overall performance of the POC tests according to manufacturer were in the rank order of AutoBio Diagnostics > Dynamiker Biotechnology = CTK Biotech > Artron Laboratories > Acro Biotech ≥ Hangzhou Alltest Biotech. Overall, these findings will facilitate selection of serological assays for the detection SARS-CoV-2-specific antibodies towards diagnosis as well as sero-epidemiological and vaccine development studies.