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The blp locus of a type 6A strain of Streptococcus pneumoniae encodes a two-peptide bacteriocin, pneumocin MN, which mediates intraspecies competition during mouse nasopharyngeal colonization. This locus is regulated by a quorum-sensing mechanism consisting of a dedicated two-component regulatory system and a peptide pheromone. Like most clinical isolates, this type 6A strain can be separated into opaque and transparent colony variants, each playing a different role during pneumococcal infection. In this study, we show that the blp locus is differentially regulated at the posttranscriptional level in pneumococcal opacity variants. Transparent and opaque variants produce equivalent amounts of blpMNPO transcript when stimulated with a synthetic pheromone, but transparent variants have no pneumocin MN-mediated inhibitory activity while opaque variants produce large zones of inhibitory activity. The differential regulation in opacity variants is driven by the two-component regulatory system CiaRH via its regulation of the serine protease HtrA. Transparent mutants deficient in CiaH or HtrA show increased pneumocin MN-mediated inhibition. In addition, these mutants demonstrate alterations in their dose response to a synthetic peptide pheromone, suggesting that HtrA activity impacts pneumocin MN production at the level of signaling. This, in addition to its known effects on competence, suggests that HtrA is a pleiotropic regulator whose protease activity affects several important bacterial pathways. The complex regulation of pneumocins may allow the pneumococcus to reserve the secretion of active peptides for situations where the benefit of their inhibitory activity outweighs the cost of their production.

Competence for genetic transformation in Streptococcus pneumoniae has previously been described as a quorum-sensing trait regulated by a secreted peptide pheromone. Recently we demonstrated that competence is also activated by reduction in the accuracy of protein biosynthesis. We have now investigated whether errors upstream of translation in the form of random genomic mutations can provide a similar stimulus. Here we show that generation of a mutator phenotype in S. pneumoniae through deletions of mutX, hexA or hexB enhanced the expression of competence. Similarly, chemical mutagenesis with the nucleotide analog dPTP promoted development of competence. To investigate the relationship between mutational load and the activation of competence, replicate lineages of the mutX strain were serially passaged under conditions of relaxed selection allowing random accumulation of secondary mutations. Competence increased with propagation in these lineages but not in control lineages having wild-type mutX. Resequencing of these derived strains revealed between 1 and 9 single nucleotide polymorphisms (SNPs) per lineage, which were broadly distributed across the genome and did not involve known regulators of competence. Notably, the frequency of competence development among the sequenced strains correlated significantly with the number of nonsynonymous mutations that had been acquired. Together, these observations provide support for the hypothesis that competence in S. pneumoniae is regulated in response to the accumulated burden of coding mutations in the bacterial genome. In contrast to previously described DNA damage response systems that are activated by physical lesions in the chromosome, this pneumococcal pathway may represent a unique stress response system that monitors the coding integrity of the genome. [ABSTRACT FROM AUTHOR]

Our 35-bed acute care pediatric hospital with a specialization in therapy and rehabilitation services experienced an outbreak of norovirus. We describe the measures implemented to prevent secondary transmission. Once laboratory testing confirmed that norovirus was responsible for the outbreak, additional cases were identified using clinical criteria of either abrupt onset of vomiting followed by diarrhea, or acute diarrhea without vomiting. In total 38 staff members, 14 patients, and 5 family members were affected over a period of 17?days. All patients, whether symptomatic or not, were placed on contact precautions. New admissions were postponed and visitor restrictions were implemented. Only soap and water was used for hand hygiene. The environmental disinfectants were confirmed to have Environmental Protection Agency kill claims for norovirus. Cleaning was done three times daily on high-touch surfaces, patient rooms, hallways, bathrooms, and staff work stations. Supplemental ultraviolet light disinfection (UVD) was deployed. Congregating in the cafeteria was discouraged by providing meals to patients and families in their rooms. We eliminated group activities in common spaces. Staff were instructed not to share food and to utilize disposable lunch containers. Symptomatic staff were furloughed for 48 hours; food handlers were furloughed for seven days. Auditing by infection prevention was initiated to assess personal protective equipment (PPE) use and hand hygiene. Measured compliance with PPE use was 96% and with hand hygiene was 95%. While the route by which infection was introduced was not identified, factors that may have contributed to the spread of disease include: sharing of food among staff, close contact during therapy, hardiness of norovirus in the environment, and low infectious dose. Lessons learned include: importance of frequent environmental cleaning, ensuring disinfectants have norovirus kill claims, staff understanding precautions and having one staff member dedicated to UVD. [ABSTRACT FROM AUTHOR]

Objective: Describe and compare the prevalence of symptomatic and asymptomatic or recently resolved respiratory infections in hospitalized children., Design: Cross-sectional study., Setting: Three hospital primary-to-quaternary care pediatric healthcare system., Patients: People less than 22 years old who underwent admission screening for respiratory viruses using a multitarget polymerase chain reaction (PCR) panel from August 2020 through April 2022., Methods: The symptom status of each patient was recorded by the ordering provider. The prevalence of each virus was described comparing symptomatic and asymptomatic patients. Results for each virus were stratified by age group and trends were examined over time., Results: Of the 32,812 eligible PCR panels collected, 12,965 (39.5%), 18,651 (56.8%), and 1,196 (3.6%) were obtained from patients who were symptomatic, asymptomatic, or had missing or unknown symptom status, respectively. Symptomatic patients were much more likely to test positive for a respiratory virus (67.3% vs 27.0%). The most common viruses detected in asymptomatic patients were rhinovirus/enterovirus (18.0%), SARS-CoV-2 (3.6%), and parainfluenza viruses (2.3%). The odds ratio of testing positive when symptomatic was significantly greater than unity for all viruses but varied by virus and age group. The proportion of positive tests for each virus was dynamic and changed with intermittent epidemics, or viral "waves.", Conclusions: More than one-quarter of children without respiratory symptoms admitted to a pediatric healthcare system had PCR-detectable respiratory viruses. Children with symptoms of a respiratory infection are nevertheless much more likely to have a respiratory virus detected by PCR., Competing Interests: None., (© The Author(s) 2024.)

Background: The COVID-19 pandemic has resulted in shortages of diagnostic tests, personal protective equipment, hospital beds, and other critical resources., Objective: We sought to improve the management of scarce resources by leveraging electronic health record (EHR) functionality, computerized provider order entry, clinical decision support (CDS), and data analytics., Methods: Due to the complex eligibility criteria for COVID-19 tests and the EHR implementation-related challenges of ordering these tests, care providers have faced obstacles in selecting the appropriate test modality. As test choice is dependent upon specific patient criteria, we built a decision tree within the EHR to automate the test selection process by using a branching series of questions that linked clinical criteria to the appropriate SARS-CoV-2 test and triggered an EHR flag for patients who met our institutional persons under investigation criteria., Results: The percentage of tests that had to be canceled and reordered due to errors in selecting the correct testing modality was 3.8% (23/608) before CDS implementation and 1% (262/26,643) after CDS implementation (P<.001). Patients for whom multiple tests were ordered during a 24-hour period accounted for 0.8% (5/608) and 0.3% (76/26,643) of pre- and post-CDS implementation orders, respectively (P=.03). Nasopharyngeal molecular assay results were positive in 3.4% (826/24,170) of patients who were classified as asymptomatic and 10.9% (1421/13,074) of symptomatic patients (P<.001). Positive tests were more frequent among asymptomatic patients with a history of exposure to COVID-19 (36/283, 12.7%) than among asymptomatic patients without such a history (790/23,887, 3.3%; P<.001)., Conclusions: The leveraging of EHRs and our CDS algorithm resulted in a decreased incidence of order entry errors and the appropriate flagging of persons under investigation. These interventions optimized reagent and personal protective equipment usage. Data regarding symptoms and COVID-19 exposure status that were collected by using the decision tree correlated with the likelihood of positive test results, suggesting that clinicians appropriately used the questions in the decision tree algorithm., (©Hung S Luu, Laura M Filkins, Jason Y Park, Dinesh Rakheja, Jefferson Tweed, Christopher Menzies, Vincent J Wang, Vineeta Mittal, Christoph U Lehmann, Michael E Sebert. Originally published in JMIR Medical Informatics (https://medinform.jmir.org), 18.10.2021.)