Publications by authors named "Michael Bachman"
Hypervirulent is associated with severe community-acquired infections. Hypervirulent colonies typically exhibit a mucoid phenotype. mucoidy is influenced by a complex combination of environmental factors and genetic mechanisms.
View Article and Find Full Text PDFInterpreting the phenotypes of alleles in genomes is complex. Whilst all strains are expected to carry a chromosomal copy conferring resistance to ampicillin, they may also carry mutations in chromosomal alleles or additional plasmid-borne alleles that have extended-spectrum β-lactamase (ESBL) activity and/or β-lactamase inhibitor (BLI) resistance activity. In addition, the role of individual mutations/a changes is not completely documented or understood.
View Article and Find Full Text PDFBloodstream infections (BSIs) are common in hospitals, often life-threatening and increasing in prevalence. Microorganisms in the blood are usually rapidly cleared by the immune system and filtering organs but, in some cases, they can cause an acute infection and trigger sepsis, a systemic response to infection that leads to circulatory collapse, multiorgan dysfunction and death. Most BSIs are caused by bacteria, although fungi also contribute to a substantial portion of cases.
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- The text discusses a healthcare-associated pathogen that leads to infections in the bloodstream, lungs, and urinary tract, highlighting the importance of its capsule polysaccharide in its ability to cause disease.
- It describes how different capsule genetic sequences (specifically KL1, KL2, and KL5) impact the pathogen’s ability to colonize organs and survive in various infection models, with KL1 and KL2 strains being particularly adept at causing disease.
- The study also finds that the capsule of KL1 and KL2 strains helps resist attack by immune cells (macrophages), which may enhance the pathogen’s survival and ability to spread during infection.
Article Synopsis
- There is a significant lack of understanding regarding how certain Gram-negative bacteria, particularly from the Enterobacterales order, cause severe blood infections (bacteremia) despite their survival strategies being more suited for different environments.
- Enterobacterales species, such as E. coli and Klebsiella pneumoniae, are prevalent in bacteremia cases, often leading to life-threatening conditions like sepsis due to immune system responses.
- Researchers identified 18 key genes linked to the bacteria's survival and tested their effects using mutant strains in a mouse model, discovering several genes whose mutations weakened the bacteria, paving the way for potential new treatments for bloodstream infections.
The primary risk factor for infection with members of the species complex is prior gut colonization, and infection is often caused by the colonizing strain. Despite the importance of the gut as a reservoir for infectious , little is known about the association between the gut microbiome and infection. To explore this relationship, we undertook a case-control study comparing the gut community structure of -colonized intensive care and hematology/oncology patients.
View Article and Find Full Text PDFObjective: Emergency medical services (EMS) clinicians are tasked with early fluid resuscitation for patients with sepsis. Traditional methods for prehospital fluid delivery are limited in speed and ease-of-use. We conducted a comparative effectiveness study of a novel rapid infusion device for prehospital fluid delivery in suspected sepsis patients.
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- Bloodstream infections can be deadly and may lead to sepsis, with Gram-negative bacteria being a major cause of these infections.
- Researchers are focusing on the transcription factor ArcA, which helps bacteria grow and survive in the bloodstream.
- Understanding how ArcA functions in these bacteria could lead to better infection models and help create new treatments.
Article Synopsis
- Gram-negative bacteremia significantly contributes to global health issues and involves three key stages: initial infection, spread, and survival in the bloodstream and filtering organs.
- Klebsiella pneumoniae is a primary cause of this condition, often starting in the lungs, and relies on various factors for its virulence, though specific mechanisms for surviving in the bloodstream were previously unclear.
- Recent research identified 58 genes that enhance K. pneumoniae's fitness during bacteremia, showing that different mechanisms are required in different organs, including adaptations for resisting oxidative stress and optimizing replication.
Article Synopsis
- * It employs machine learning to analyze the gut community structure, revealing differences between infected and non-infected patients, with relative abundance of particular bacteria being the most significant factor.
- * The findings suggest that integrating gut microbiome data with bacterial genetics and clinical information can enhance predictions about infections in colonized patients, highlighting potential for early intervention strategies.
Objectives: Despite EMS-implemented screening and treatment protocols for suspected sepsis patients, prehospital fluid therapy is variable. We sought to describe prehospital fluid administration in suspected sepsis patients, including demographic and clinical factors associated with fluid outcomes.
Methods: A retrospective cohort of adult patients from a large, county-wide EMS system from January 2018-February 2020 was identified.
Healthcare-acquired infections are a leading cause of disease in patients that are hospitalized or in long-term-care facilities. Klebsiella pneumoniae (Kp) is a leading cause of bacteremia, pneumonia, and urinary tract infections in these settings. Previous studies have established that the operon, a genetic locus that confers tellurite oxide (KTeO) resistance, is associated with infection in colonized patients.
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- The study investigates how certain genes in Klebsiella pneumoniae are linked to the transition from gut colonization to infection, highlighting the genetic differences between strains.
- Researchers compared cases of infection (N=85) with asymptomatic carriers (N=160) to find 37 genes associated with infection risk, many related to stress and antibiotic resistance rather than traditional virulence factors.
- Five of these genes were further validated in a separate group, suggesting their role in understanding infection progression in patients carrying Klebsiella bacteria.
Klebsiella pneumoniae is a leading cause of Gram-negative bacteremia, which is a major source of morbidity and mortality worldwide. Gram-negative bacteremia requires three major steps: primary site infection, dissemination to the blood, and bloodstream survival. Because K.
View Article and Find Full Text PDFClinical Microbiology Open (CMO), a meeting supported by the American Society for Microbiology's Clinical and Public Health Microbiology Committee (CPHMC) and Corporate Council, provides a unique interactive platform for leaders from diagnostic microbiology laboratories, industry, and federal agencies to discuss the current and future state of the clinical microbiology laboratory. The purpose is to leverage the group's diverse views and expertise to address critical challenges, and discuss potential collaborative opportunities for diagnostic microbiology, through the utilization of varied resources. The first and second CMO meetings were held in 2018 and 2019, respectively.
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- ArcAB is a bacterial transcriptional regulator consisting of the sensor kinase ArcB and the response regulator ArcA, and it mainly senses oxygen consumption.
- The review discusses how the bacterial quinone pool influences the activity of ArcAB, highlighting the ongoing debates about the mechanisms behind this regulation.
- Recent findings suggest that ArcAB may also regulate cellular processes under aerobic conditions, challenging its traditional view as only an anaerobic regulator, and its implications for infection-related processes are examined.
Context.—: Multiplex stool polymerase chain reaction tests (SPTs) simultaneously test for many enteric pathogens. However, the clinical significance of a positive result, particularly in the context of chronic gastrointestinal disease, remains controversial.
View Article and Find Full Text PDFBackground: Diagnostic sensitivities of point-of-care SARS-CoV-2 assays depend on specimen type and population-specific viral loads. Evaluation of these assays require "direct" specimens from paired-swab studies rather than more accessible residual specimens in viral transport media (VTM).
Methods: Residual VTM and limit-of-detection studies were conducted on Abbott ID NOW™ COVID-19, Quidel Sofia 2™ SARS Antigen FIA, and DiaSorin Simplexa™ COVID-19 Direct assays, with cycle threshold (CT) adjustments to approximate direct-specimen testing based on gene-target doubling each PCR cycle.
Article Synopsis
- Quality control rules, known as Westgard rules, are crucial in viral load testing to detect errors, balancing patient safety with the costs of false rejections.
- The study utilized Unity Real Time software to analyze QC data and assess performance of FDA-approved and laboratory-developed viral load assays over a testing period of 73 to 83 days.
- Results showed that sigma values indicated high test performance for CMV and HIV, allowing for recommendations to relax QC rules, which could reduce false rejection rates significantly, especially for Epstein-Barr virus testing.
Background: Despite the recent emergence of plasmid-mediated colistin resistance, the epidemiology and mechanisms of colistin-resistant Enterobacterales (CORE) infections remain poorly understood.
Methods: A case-case-control study was conducted utilizing routine clinical isolates obtained at a single tertiary health system in Ann Arbor, Michigan. Patients with CORE isolates from January 1, 2016, to March 31, 2017, were matched 1:1 with patients with colistin-susceptible Enterobacterales (COSE) and uninfected controls.
Article Synopsis
- Bloodstream infections (BSI) represent a significant public health challenge due to their high mortality rates and rising antibiotic resistance, particularly among Gram-negative bacteria.
- The study focused on six common pathogens (E. coli, S. marcescens, K. pneumoniae, E. hormaechei, C. freundii, and A. baumannii) to analyze their infection dynamics and replication rates in a mouse model.
- Findings revealed that while some bacteria like K. pneumoniae and S. marcescens grew rapidly in specific organs, others were gradually cleared, indicating varying abilities to establish and maintain infections in the host.
Article Synopsis
- Klebsiella is a common intestinal bacterium found in hospitalized patients and is a major contributor to health care-associated infections, with a notable risk for those who are colonized.* -
- A study tracked 1,978 patients who were colonized by Klebsiella for 90 days, revealing a 4.3% infection rate, with a mean infection onset of about 21 days; most infections originated from the same strain that colonized the patients.* -
- Factors such as overall health, depression, and low albumin levels at swab collection were linked to an increased risk of infection, suggesting that monitoring colonized patients could help prevent illness.*
Article Synopsis
- Klebsiella pneumoniae and related species are common causes of healthcare-associated infections, often originating from intestinal strains in patients.
- A case-control study utilized a multiplex quantitative PCR assay to assess the connection between Klebsiella colonization density and subsequent infections by comparing infected patients with colonized but uninfected individuals.
- Results showed that higher relative abundance of Klebsiella in rectal swabs was significantly associated with infection risk, indicating that measuring colonization density could help identify at-risk hospitalized patients.
Article Synopsis
- - Klebsiella pneumoniae (Kp) is a major cause of healthcare-related infections, leading to increased patient illness and healthcare costs, particularly linked to gut colonization where the infecting strain often originates.
- - A study identified a specific tellurite-resistance (ter) operon that seems to have a crucial but not fully understood role in Kp infections, separate from other virulence factors and antibiotic resistance genes.
- - Research using mouse models demonstrated that the ter operon boosts Kp's survival in the gut but is not essential during severe infections; its effect is influenced by the gut microbiota, particularly those that produce short-chain fatty acids.
Background: There is limited evidence on the performance of emergent large-vessel occlusion (LVO) stroke screening tools when used by emergency medical services (EMS) and emergency department (ED) providers. We assessed the validity and predictive value of the vision, aphasia, neglect (VAN) assessment when completed by EMS and in the ED among suspected stroke patients.
Methods: We conducted a retrospective study of VAN performed by EMS providers and VAN inferred from the National Institutes of Health Stroke Scale performed by ED nurses at a single hospital.