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Aims: To monitor the decay of E. coli O157 in soil (loamy sand) on a scout campsite following an outbreak in humans. Methods and Results: Samples of soil and sheep faeces were collected from the campsite and tested for the presence of E. coli O157 by immunomagnetic separation (IMS) after enrichment in buffered peptone water + vancomycin at 42°C for 6 h. Enumeration of target was carried out by direct plating onto sorbitol MacConkey agar plates supplemented with cefixime and tellurite (CTSMAC) incubated at 37°C for 24 h. Low numbers (< 100 g )1 ) were estimated by the most probable number (3-tube MPN) technique. Conclusions: Survival was observed for 15 weeks. Significance and Impact of the Study: A number of laboratory studies have followed the decay of E. coli O157 in soil, animal faeces and water. This study follows (for the first time) the decay of the organism in soil after an outbreak associated with sheep. It demonstrates the long-term persistence of the organism in the environment and the results will be potentially important in performing risk assessments for both human and animal infection.

The year 2020 has seen the emergence of a global pandemic as a result of the disease COVID-19. This report reviews knowledge of the transmission of COVID-19 indoors, examines the evidence for mitigating measures, and considers the implications for wintertime with a focus on ventilation.

Primers were designed to amplify the rpoB gene of Neisseria meningitidis. The region of the gene amplified covered clusters I and II of the rifampin resistance (Rifr) mutation sites identified in Escherichia coli. DNAs from six Rifr isolates and 21 rifampin-susceptible isolates from the United Kingdom representing a number of serogroups were amplified and sequenced. All six Rifr isolates had identical DNA sequences and the same amino acid change, a His to an Asn change at position 35 (H35N). This His residue is equivalent to the His residue at position 526 in E. coli, one of the known Rifr mutation sites. DNAs from an additional six Rifr mutations generated in vitro were amplified and sequenced. Three had H35Y changes, one had an H35R change, one had an H35N change and one had an S40F change. The predominance of mutations at the His residue at position 35 in Rifr N. meningitidis isolates suggests that it plays a critical role in the selection of antibiotic-resistant variants. All six Rifr isolates belonged to the same clonal group when analyzed by restriction enzyme analysis and pulsed-field gel electrophoresis. These data suggest that a single clone of Rifr N. meningitidis is present and widespread throughout the United Kingdom.

Staphylococcal DNA was digested with endonucleases and probed with labelled ribosomal RNA (rRNA) from Escherichia coli. Reproducible restriction patterns containing between seven and 22 bands were obtained for seven different species of staphylococci. These profiles were species-specific with different strains of a particular species sharing an identical or similar restriction pattern. The results reported here indicate that rRNA gene restriction pattern analyses have an application in the taxonomy of staphylococci.

SUMMARYThe polypeptides of BSCt cells infected with vaccinia virus and pulse labelled with [l~C]-protein hydrolysate or [35S]-methionine have been examined by discontinuous polyacrylamide gel electrophoresis followed by autoradiography. About 80 virus induced polypeptides were detected, 30 appearing before and 50 after the onset of virus DNA synthesis. These were termed pre-and post-replicative polypeptides respectively. The synthesis of most pre-replicative polypeptides was turned off shortly after the peak of virus DNA synthesis; when virus DNA synthesis was inhibited this turn-off did not occur and post-replicative polypeptides were not made. The synthesis of some post-replicative polypeptides started at about the time of maximal DNA synthesis, reached a peak about I h later, and was then turned off. Other post-replicative polypeptides whose synthesis started at this time were made for prolonged periods. The synthesis of most post-replicative polypeptides started about I h after the time of maximal virus DNA synthesis and continued thereafter for prolonged periods. The stability of pre-and post-replicative polypeptides was examined in pulse-chase experiments; most pre-replicative and 'early' post-replicative polypeptides were stable for prolonged periods, whereas, during a chase, eleven 'late' post-replicative polypeptides disappeared and seven new polypeptides appeared.

Rifampin-resistant (Rifr) Neisseria meningitidis strains are known to have single point mutations in the central conserved regions of the rpoB gene. We have demonstrated two distinct resistance phenotypes in strains with identical mutations in this region, an intermediate level of resistance in Rifr clinical isolates and a high level of resistance in mutants selected in vitro. The possible role of membrane permeability in the latter was investigated by measuring MICs in the presence of Tween 80; values for high-level-resistance mutants were reduced to intermediate levels, whereas those for intermediate-level-resistance strains were unaffected. The highly resistant mutants were also found to have increased resistance to Triton X-100 and gentian violet. Sequencing of the meningococcal mtrR gene and its promoter region (which determine resistance to hydrophobic agents in Neisseria gonorrhoeae) from susceptible or intermediate strains and highly resistant mutants generated from them showed no mutation within this region. Two-dimensional gel electrophoresis of two parent and Rif mutant strains showed identical shifts in the pI of one protein, indicating that differences between the parent and the highly Rifr mutant are not confined to the rpoB gene. These results indicate that both permeability and rpoB mutations play a role in determining the resistance of N. meningitidis to rifampin.

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