Rapid antibiotic susceptibility testing from blood culture bottles with species agnostic real-time polymerase chain reaction.

Development and implementation of rapid antimicrobial susceptibility testing is critical for guiding patient care and improving clinical outcomes, especially in cases of sepsis. One approach to reduce the time-to-answer for antimicrobial susceptibility is monitoring the inhibition of DNA production, as differences in DNA concentrations are more quickly impacted compared to optical density changes in traditional antimicrobial susceptibility testing. Here, we use real-time PCR to rapidly determine antimicrobial susceptibility after short incubations with antibiotic. Application of this assay to a collection of 144 isolates in mock blood culture, covering medically relevant pathogens displaying high rates of resistance, provided susceptibility data in under 4 hours. This assay provided categorical agreement with a reference method in 96.3% of cases across all species. Sequencing of a subset of PCR amplicons showed accurate genus level identification. Overall, implementation of this method could provide accurate susceptibility results with a reduced time-to-answer for a number of medically relevant bacteria commonly isolated from blood culture

Distribution of ΔCq values for tested isolates.

The ΔCq values for all isolates are shown, separated by antibiotic and susceptibility as determined by the reference method (BMD), for (a) Enterobacteriaceae spp., (b) A. baumannii, (c) P. aeruginosa, (d) E. faecium, and (e) S. aureus. Isolate-antibiotic combinations that resulted in minor, major, or very major errors are colored red. Sus, susceptible; int, intermediate; res, resistant; Cip, ciprofloxacin; Gen, gentamicin; Imi, imipenem; Van, vancomycin; Amp, ampicillin; Oxa, oxacillin.</p

Categorical agreement and errors for the tested isolates.

Categorical agreement and errors for the tested isolates.</p

Number of tested isolates and the antibiotic concentration used in the qPCR assay.

Number of tested isolates and the antibiotic concentration used in the qPCR assay.</p

Comparison of transcriptional responses between pathogenic and nonpathogenic hantavirus infections in Syrian hamsters using NanoString

Background Syrian hamsters infected with Andes virus (ANDV) develop a disease that recapitulates many of the salient features of human hantavirus pulmonary syndrome (HPS), including lethality. Infection of hamsters with Hantaan virus (HTNV) results in an asymptomatic, disseminated infection. In order to explore this dichotomy, we examined the transcriptome of ANDV- and HTNV-infected hamsters. Results Using NanoString technology, we examined kinetic transcriptional responses in whole blood collected from ANDV- and HTNV-infected hamsters. Of the 770 genes analyzed, key differences were noted in the kinetics of type I interferon sensing and signaling responses, complement activation, and apoptosis pathways between ANDV- and HTNV-infected hamsters. Conclusions Delayed activation of type I interferon responses in ANDV-infected hamsters represents a potential mechanism that ANDV uses to subvert host immune responses and enhance disease. This is the first genome-wide analysis of hantavirus-infected hamsters and provides insight into potential avenues for therapeutics to hantavirus disease. </jats:sec

Read mapping of sequenced qPCR amplicons.

Read mapping of sequenced qPCR amplicons.</p

Rapid identification of bacterial select agents using loop-mediated isothermal amplification

Abstract Background Point of need diagnostics provide efficient testing capability for remote or austere locations, decreasing the time to answer by minimizing travel or sample transport requirements. Loop-mediated isothermal amplification (LAMP) is an appealing technology for point-of-need diagnostics due to its rapid analysis time and minimal instrumentation requirements. Methods Here, we designed and optimized nine LAMP assays that are sensitive and specific to targeted bacterial select agents including Bacillus anthracis, Francisella tularensis, Yersinia pestis, and Brucella spp. Evaluation of each assay determined preliminary limit of detection (LOD) with LOD confirmed across 60 replicates (≥ 95% positivity rate). Testing across a robust set of strains of the target agent, common DNA agents, and near-neighbors documented sensitivity and specificity for independent assays. Results Specifically, all assays were 100% specific and sensitive except for Y. pestis Caf1 (90% inclusive across Y. pestis strains). Conclusion Here, we optimized assay turn-around-time, decreasing a standard 60 min traditional polymerase chain reaction (PCR) to 30 min using LAMP with positive results in as little as 5–10 min. Incorporating point of need sample processing and evaluating the potential inhibitory impact of sample matrices such as whole blood and soil would be needed to enable this test system for use on field-forward clinical and environmental sample testing

Host response transcriptomic analysis of Crimean-Congo hemorrhagic fever pathogenesis in the cynomolgus macaque model

AbstractCrimean-Congo hemorrhagic fever virus (CCHFV) is a highly pathogenic tick-borne RNA virus prevalent in Asia, Europe, and Africa, and can cause a hemorrhagic disease (CCHF) in humans with mortality rates as high as 60%. A general lack of both effective medical countermeasures and a comprehensive understanding of disease pathogenesis is partly driven by an historical lack of viable CCHF animal models. Recently, a cynomolgous macaque model of CCHF disease was developed. Here, we document the targeted transcriptomic response of non-human primates (NHP) to two different CCHFV strains; Afghan09-2990 and Kosova Hoti that both yielded a mild CCHF disease state. We utilized a targeted gene panel to elucidate the transcriptomic changes occurring in NHP whole blood during CCHFV infection; a first for any primate species. We show numerous upregulated genes starting at 1 day post-challenge through 14 days post-challenge. Early gene changes fell predominantly in the interferon stimulated gene family with later gene changes coinciding with an adaptive immune response to the virus. There are subtle differences between viral strains, namely duration of the differentially expressed gene response and biological pathways enriched. After recovery, NHPs showed no lasting transcriptomic changes at the end of sample collection.</jats:p

Decreased antibiotic susceptibility driven by global remodeling of the Klebsiella pneumoniae proteome

Bacteria can circumvent the effect of antibiotics by transitioning to a poorly understood physiological state that does not involve conventional genetic elements of resistance. Here we examine antibiotic susceptibility with a Class A β-lactamase+ invasive strain of Klebsiella pneumoniae that was isolated from a lethal outbreak within laboratory colonies of Chlorocebus aethiops sabaeus monkeys. Bacterial responses to the ribosomal synthesis inhibitors streptomycin and doxycycline resulted in distinct proteomic adjustments that facilitated decreased susceptibility to each antibiotic. Drug-specific changes to proteomes included proteins for receptor-mediated membrane transport and sugar utilization, central metabolism, and capsule production, while mechanisms common to both antibiotics included elevated scavenging of reactive oxygen species and turnover of misfolded proteins. Resistance to combined antibiotics presented integrated adjustments to protein levels as well as unique drug-specific proteomic features. Our results demonstrate that dampening of Klebsiella pneumoniae susceptibility involves global remodeling of the bacterial proteome to counter the effects of antibiotics and stabilize growth.http://www.mcponline.org/content/early/2019/01/07/mcp.RA118.00073