The complex pathogenesis of bacteremia: from antimicrobial clearance mechanisms to the genetic background of the host

Culture-independent identification of bloodstream infections from whole blood: prospective evaluation in specimens of known infection status

Sepsis caused by bloodstream infection (BSI) is a major healthcare burden and a leading cause of morbidity and mortality worldwide. Timely diagnosis is critical to optimize clinical outcome, as mortality rates rise every hour treatment is delayed. Blood culture remains the "gold standard" for diagnosis but is limited by its long turnaround time (1-7 days depending on the organism) and its potential to provide false-negative results due to interference by antimicrobial therapy or the presence of mixed (i.e., polymicrobial) infections. In this paper, we evaluated the performance of resistance and pathogen ID/BSI, a direct-from-specimen molecular assay. To reduce the false-positivity rate common with molecular methods, this assay isolates and detects genomic material only from viable microorganisms in the blood by incorporating a novel precursor step to selectively lyse host and non-viable microbial cells and remove cell-free genomic material prior to lysis and analysis of microbial cells. Here, we demonstrate that the assay is free of interference from host immune cells and common antimicrobial agents at elevated concentrations. We also demonstrate the accuracy of this technology in a prospective cohort pilot study of individuals with known sepsis/BSI status, including samples from both positive and negative individuals.

IMPORTANCE

Blood culture remains the "gold standard" for the diagnosis of sepsis/bloodstream infection (BSI) but has many limitations which may lead to a delay in appropriate and accurate treatment in patients. Molecular diagnostic methods have the potential for markedly improving the management of such patients through faster turnaround times and increased accuracy. But molecular diagnostic methods have not been widely adopted for the identification of BSIs. By incorporating a precursor step of selective lysis of host and non-viable microorganisms, our resistance and pathogen ID (RaPID)/BSI molecular assay addresses many limitations of blood culture and other molecular assay. The RaPID/BSI assay has an approximate turnaround time of 4 hours, thereby significantly reducing the time to appropriate and accurate diagnosis of causative microorganisms in such patients. The short turnaround time also allows for close to real-time tracking of pathogenic clearance of microorganisms from the blood of these patients or if a change of antimicrobial regimen is required. Thus, the RaPID/BSI molecular assay helps with optimization of antimicrobial stewardship; prompt and accurate diagnosis of sepsis/BSI could help target timely treatment and reduce mortality and morbidity in such patients.

Exertional Stress-induced Pathogenic Luminal Content Translocation - Friend or Foe?

The incidence of perturbed gastrointestinal integrity, as well as resulting systemic immune responses and gastrointestinal symptoms, otherwise known as exercised-induced gastrointestinal syndrome (EIGS), is common among individuals who partake in prolonged exercise. EIGS may cause the translocation of pathogenic material, including whole bacteria and bacterial endotoxins, from the lumen into circulation, which may progress into clinical consequences such as sepsis, and potentially subsequent fatality. However, further investigation is warranted to assess the possibility of food allergen and/or digestive enzyme luminal to circulatory translocation in response to exercise, and the clinical consequences. Findings from this narrative literature review demonstrate evidence that whole bacteria and bacterial endotoxins translocation from the gastrointestinal lumen to systemic circulation occurs in response to exercise stress, with a greater propensity of translocation occurring with accompanying heat exposure. It has also been demonstrated that food allergens can translocate from the lumen to systemic circulation in response to exercise stress and initiate anaphylaxis. To date, no research investigating the effect of exercise on the translocation of digestive enzymes from the lumen into systemic circulation exists. It is evident that EIGS and consequential pathogenic translocation presents life-threatening clinical implications, warranting the development and implementation of effective management strategies in at-risk populations.

Neutrophil-targeted combinatorial nanosystems for suppressing bacteremia-associated hyperinflammation and MRSA infection to improve survival rates

There is currently no specific and effective treatment for bacteremia-mediated sepsis. Hence, this study engineered a combinatorial nanosystem containing neutrophil-targeted roflumilast-loaded nanocarriers and non-targeted fusidic acid-loaded nanoparticles to enable the dual mitigation of bacteremia-associated inflammation and methicillin-resistant Staphylococcus aureus (MRSA) infection. The targeted nanoparticles were developed by conjugating anti-lymphocyte antigen 6 complex locus G6D (Ly6G) antibody fragment on the nanoparticulate surface. The particle size and zeta potential of the as-prepared nanosystem were about 200 nm and -25 mV, respectively. The antibody-conjugated nanoparticles showed a three-fold increase in neutrophil internalization compared to the unfunctionalized nanoparticles. As a selective phosphodiesterase (PDE) 4 inhibitor, the roflumilast in the nanocarriers largely inhibited cytokine/chemokine release from the activated neutrophils. The fusidic acid-loaded nanocarriers were vital to eliminate biofilm MRSA colony by 3 log units. The nanoparticles drastically decreased the intracellular bacterial count compared to the free antibiotic. The in vivo mouse bioimaging demonstrated prolonged retention of the nanosystem in the circulation with limited organ distribution and liver metabolism. In the mouse bacteremia model, the multifunctional nanosystem produced a 1‒2 log reduction of MRSA burden in peripheral organs and blood. The functionalized nanosystem arrested the cytokine/chemokine overexpression greater than the unfunctionalized nanocarriers and free drugs. The combinatory nanosystem also extended the median survival time from 50 to 103 h. No toxicity from the nanoformulation was found based on histology and serum biochemistry. Furthermore, our data proved that the active neutrophil targeting by the versatile nanosystem efficiently alleviated MRSA infection and organ dysfunction caused by bacteremia. STATEMENT OF SIGNIFICANCE: Bacteremia-mediated sepsis poses a significant challenge in clinical practice, as there is currently no specific and effective treatment available. In our study, we have developed a novel combinatorial nanosystem to address this issue. Our nanosystem consists of neutrophil-targeted roflumilast-loaded nanocarriers and non-targeted fusidic acid-loaded nanoparticles, enabling the simultaneous mitigation of bacteremia-associated inflammation and MRSA infection. Our nanosystem demonstrated the decreased neutrophil activation, effective inhibition of cytokine release, elimination of MRSA biofilm colonies, and reduced intracellular bacterial counts. In vivo experiments showed prolonged circulation, limited organ distribution, and increased survival rates in a mouse bacteremia model. Importantly, our nanosystem exhibited no toxicity based on comprehensive assessments.

Genetic and immune determinants of E. coli liver abscess formation

Systemic infections can yield distinct outcomes in different tissues. In mice, intravenous inoculation of Escherichia coli leads to bacterial replication within liver abscesses, while other organs such as the spleen clear the pathogen. Abscesses are macroscopic necrotic regions that comprise the vast majority of the bacterial burden in the animal, yet little is known about the processes underlying their formation. Here, we characterize E. coli liver abscesses and identify host determinants of abscess susceptibility. Spatial transcriptomics revealed that liver abscesses are associated with heterogenous immune cell clusters comprised of macrophages, neutrophils, dendritic cells, innate lymphoid cells, and T-cells that surround necrotic regions of the liver. Abscess susceptibility is heightened in the C57BL lineage, particularly in C57BL/6N females. Backcross analyses demonstrated that abscess susceptibility is a polygenic trait inherited in a sex-dependent manner without direct linkage to sex chromosomes. As early as 1 d post infection, the magnitude of E. coli replication in the liver distinguishes abscess-susceptible and abscess-resistant strains of mice, suggesting that the immune pathways that regulate abscess formation are induced within hours. We characterized the early hepatic response with single-cell RNA sequencing and found that mice with reduced activation of early inflammatory responses, such as those lacking the LPS receptor TLR4 (Toll-like receptor 4), are resistant to abscess formation. Experiments with barcoded E. coli revealed that TLR4 mediates a tradeoff between abscess formation and bacterial clearance. Together, our findings define hallmarks of E. coli liver abscess formation and suggest that hyperactivation of the hepatic innate immune response drives liver abscess susceptibility.

Bacteremia in Patients with Sepsis in the ICU: Does It Make a Difference?

Sepsis (and septic shock) is on of the most common causes of death worldwide. Bacteremia often, but not necessarily, occurs in septic patients, but the impact of true bacteremia on a patient's clinical characteristics and outcome remains unclear. The main aim of this study was to compare the characteristics and outcome of a well-defined cohort of 258 septic patients with and without bacteremia treated in the intensive care unit (ICU) of a tertiary center hospital in Prague, Czech Republic. As expected, more frequently, bacteremia was present in patients without previous antibiotic treatment. A higher proportion of bacteremia was observed in patients with infective endocarditis as well as catheter-related and soft tissue infections in contrast to respiratory sepsis. Multivariant analysis showed increased severity of clinical status and higher Charlson comorbidity index (CCI) as variables with significant influence on mortality. Bacteremia appears to be associated with higher mortality rates and length of ICU stay in comparison with nonbacteremic counterparts, but this difference did not reach statistical significance. The presence of bacteremia, apart from previous antibiotic treatment, may be related to the site of infection.

Bacteremia in Severe Mastitis of Dairy Cows

The aim of this cross-sectional study was to investigate the occurrence of bacteremia in severe mastitis cases of dairy cows. Milk and corresponding blood samples of 77 cases of severe mastitis were bacteriologically examined. All samples (milk and blood) were incubated aerobically and anaerobically to also investigate the role of obligate anaerobic microorganisms in addition to aerobic microorganisms in severe mastitis. Bacteremia occurred if identical bacterial strains were isolated from milk and blood samples of the same case. In addition, pathogen shedding was examined, and the data of animals and weather were collected to determine associated factors for the occurrence of bacteremia in severe mastitis. If Gram-negative bacteria were detected in milk samples, a Limulus test (detection of endotoxins) was also performed for corresponding blood samples without the growth of Gram-negative bacteria. In 74 cases (96.1%), microbial growth was detected in aerobically incubated milk samples. The most-frequently isolated bacteria in milk samples were Escherichia (E.) coli (48.9%), Streptococcus (S.) spp. (18.1%), and Klebsiella (K.) spp. (16%). Obligatory anaerobic microorganisms were not isolated. In 72 cases (93.5%) of the aerobically examined blood samples, microbial growth was detected. The most-frequently isolated pathogens in blood samples were non-aureus Staphylococci (NaS) (40.6%) and Bacillus spp. (12.3%). The Limulus test was positive for 60.5% of cases, which means a detection of endotoxins in most blood samples without the growth of Gram-negative bacteria. Bacteremia was confirmed in 12 cases (15.5%) for K. pneumoniae (5/12), E. coli (4/12), S. dysgalactiae (2/12), and S. uberis (1/12). The mortality rate (deceased or culled) was 66.6% for cases with bacteremia and 34.1% for cases without bacteremia. High pathogen shedding and high humidity were associated with the occurrence of bacteremia in severe mastitis.

Genetic and immune determinants of E. coli liver abscess formation

Systemic infections can yield distinct outcomes in different tissues. In mice, intravenous inoculation of E. coli leads to bacterial replication within liver abscesses while other organs such as the spleen largely clear the pathogen. Abscesses are macroscopic necrotic regions that comprise the vast majority of the bacterial burden in the animal, yet little is known about the processes underlying their formation. Here, we characterize E. coli liver abscesses and identify host determinants of abscess susceptibility. Spatial transcriptomics revealed that liver abscesses are associated with heterogenous immune cell clusters comprised of macrophages, neutrophils, dendritic cells, innate lymphoid cells, and T-cells that surround necrotic regions of the liver. Susceptibility to liver abscesses is heightened in the C57BL/6 lineage, particularly in C57BL/6N females. Backcross analyses demonstrated that abscess susceptibility is a polygenic trait inherited in a sex-dependent manner without direct linkage to sex chromosomes. As early as one day post infection, the magnitude of E. coli replication in the liver distinguishes abscess-susceptible and abscess-resistant strains of mice, suggesting that the immune pathways that regulate abscess formation are induced within hours. We characterized the early hepatic response with single-cell RNA sequencing and found that mice with reduced activation of early inflammatory responses, such as those lacking the LPS receptor TLR4, are resistant to abscess formation. Experiments with barcoded E. coli revealed that TLR4 mediates a tradeoff between abscess formation and bacterial clearance. Together, our findings define hallmarks of E. coli liver abscess formation and suggest that hyperactivation of the hepatic innate immune response drives liver abscess susceptibility.

Predictive value of cell population data with Sysmex XN-series hematology analyzer for culture-proven bacteremia

Background

Cell population data (CPD) parameters related to neutrophils, such as fluorescent light intensity (NE-SFL) and fluorescent light distribution width index (NE-WY), have emerged as potential biomarkers for sepsis. However, the diagnostic implication in acute bacterial infection remains unclear. This study assessed the diagnostic value of NE-WY and NE-SFL for bacteremia in patients with acute bacterial infections, and those associations with other sepsis biomarkers.

Methods

Patients with acute bacterial infections were enrolled in this prospective observational cohort study. For all patients, a blood sample, with at least two sets of blood cultures, were collected at the onset of infection. Microbiological evaluation included examination of the blood bacterial load using PCR. CPD was assessed using Automated Hematology analyzer Sysmex series XN-2000. Serum levels of procalcitonin (PCT), interleukin-6 (IL-6), presepsin, and CRP were also assessed.

Results

Of 93 patients with acute bacterial infection, 24 developed culture-proven bacteremia and 69 did not. NE-SFL and NE-WY were significantly higher in patients with bacteremia than in those without bacteremia (p < 0.005, respectively), and were significantly correlated with the bacterial load determined by PCR (r = 0.384 and r = 0.374, p < 0.005, respectively). To assess the diagnostic value for bacteremia, receiver operating characteristic curve analysis was used. NE-SFL and NE-WY showed an area under the curve of 0.685 and 0.708, respectively, while those of PCT, IL-6, presepsin, and CRP were 0.744, 0.778, 0.685, and 0.528, respectively. Correlation analysis showed that the levels of NE-WY and NE-SFL were strongly correlated with PCT and IL-6 levels.

Conclusion

This study demonstrated that NE-WY and NE-SFL could predict bacteremia in a manner that may be different from that of other indicators. These findings suggest there are potential benefits of NE-WY/NE-SFL in predicting severe bacterial infections.

Disseminated intravascular coagulation phenotype is regulated by the TRPM7 channel during sepsis

BACKGROUND

Sepsis is an uncontrolled inflammatory response against a systemic infection that results in elevated mortality, mainly induced by bacterial products known as endotoxins, producing endotoxemia. Disseminated intravascular coagulation (DIC) is frequently observed in septic patients and is associated with organ failure and death. Sepsis activates endothelial cells (ECs), promoting a prothrombotic phenotype contributing to DIC. Ion channel-mediated calcium permeability participates in coagulation. The transient reception potential melastatin 7 (TRPM7) non-selective divalent cation channel that also contains an α-kinase domain, which is permeable to divalent cations including Ca²⁺, regulates endotoxin-stimulated calcium permeability in ECs and is associated with increased mortality in septic patients. However, whether endothelial TRPM7 mediates endotoxemia-induced coagulation is not known. Therefore, our aim was to examine if TRPM7 mediates coagulation during endotoxemia.

RESULTS

The results showed that TRPM7 regulated endotoxin-induced platelet and neutrophil adhesion to ECs, dependent on the TRPM7 ion channel activity and by the α-kinase function. Endotoxic animals showed that TRPM7 mediated neutrophil rolling on blood vessels and intravascular coagulation. TRPM7 mediated the increased expression of the adhesion proteins, von Willebrand factor (vWF), intercellular adhesion molecule 1 (ICAM-1), and P-selectin, which were also mediated by the TRPM7 α-kinase function. Notably, endotoxin-induced expression of vWF, ICAM-1 and P-selectin were required for endotoxin-induced platelet and neutrophil adhesion to ECs. Endotoxemic rats showed increased endothelial TRPM7 expression associated with a procoagulant phenotype, liver and kidney dysfunction, increased death events and an increased relative risk of death. Interestingly, circulating ECs (CECs) from septic shock patients (SSPs) showed increased TRPM7 expression associated with increased DIC scores and decreased survival times. Additionally, SSPs with a high expression of TRPM7 in CECs showed increased mortality and relative risk of death. Notably, CECs from SSPs showed significant results from the AUROC analyses for predicting mortality in SSPs that were better than the Acute Physiology and Chronic Health Evaluation II (APACHE II) and the Sequential Organ Failure Assessment (SOFA) scores.

CONCLUSIONS

Our study demonstrates that sepsis-induced DIC is mediated by TRPM7 in ECs. TRPM7 ion channel activity and α-kinase function are required by DIC-mediated sepsis-induced organ dysfunction and its expression are associated with increased mortality during sepsis. TRPM7 appears as a new prognostic biomarker to predict mortality associated to DIC in SSPs, and as a novel target for drug development against DIC during infectious inflammatory diseases.

Therapeutic Bacteriophages for Gram-Negative Bacterial Infections in Animals and Humans

Drug-resistant Gram-negative bacterial pathogens are an increasingly serious health threat causing worldwide nosocomial infections with high morbidity and mortality. Of these, the most prevalent and severe are Pseudomonas aeruginosa, Klebsiella pneumoniae, Escherichia coli, Acinetobacter baumannii, and Salmonella typhimurium. The extended use of antibiotics has led to the emergence of multidrug resistance in these bacteria. Drug-inactivating enzymes produced by these bacteria, as well as other resistance mechanisms, render drugs ineffective and make treatment of such infections more difficult and complicated. This makes the development of novel antimicrobial agents an urgent necessity. Bacteriophages, which are bacteria-killing viruses first discovered in 1915, have been used as therapeutic antimicrobials in the past, but their use was abandoned due to the widespread availability of antibiotics in the 20th century. The emergence, however, of drug-resistant pathogens has re-affirmed the need for bacteriophages as therapeutic strategies. This review describes the use of bacteriophages as novel agents to combat this rapidly emerging public health crisis by comprehensively enumerating and discussing the innovative use of bacteriophages in both animal models and in patients infected by Gram-negative bacteria.

Bacteriological profile and antibiogram of blood culture isolates from bloodstream infections in a rural tertiary hospital in Nigeria

Background

Bloodstream infections (BSIs) are a cause of significant morbidity and mortality requiring urgent antibiotic treatment. However, there is widespread antibiotic-resistance from the bacterial causes, necessitating regular surveillance for drug-resistant bacteria and their antibiograms.

Objective

This study isolated and identified various bacterial causes of BSIs, determined their antibiotic susceptibility patterns, and determined the best empirical treatment for cases of BSI in the setting.

Methods

A cross-sectional study was carried out at the Federal Teaching Hospital, Ido-Ekiti, Nigeria between June 2020 and February 2021 on 177 blood culture samples from cases of BSI. Identification of isolated bacteria and antibiotic susceptibility testing of the isolates were carried out following the standard protocol.

Results

Culture positivity in this study was 19.2%. No significant difference was seen in culture positivity between male and female participants (p = 0.97). Gram-negative enteric bacteria were predominantly isolated (67.6%), including Escherichia coli (29.4%) and Klebsiella aerogenes (20.6%). Staphylococcus aureus was the most common Gram-positive bacterium isolated (23.5%). Three (37.5%) S. aureus isolates were methicillin-resistant. All isolates were sensitive to meropenem, and 97.1% were sensitive to imipenem; other sensitivity patterns were: ceftazidime (85.3%), ciprofloxacin (79.4%), ofloxacin (79.4%), and gentamicin (76.5%). There was low sensitivity to ampicillin (32.4%) and cotrimoxazole (38.2%). All Gram-positive isolates, including methicillin-resistant S. aureus, were sensitive to vancomycin.

Conclusion

Regular surveillance of isolate sensitivity patterns, formulation of hospital antibiotic policies based on existing data and compliance with treatment guidelines will promote rational antibiotic use and reduce resistance among bacteria.

Insights on Gut and Skin Wound Microbiome in Stranded Indo-Pacific Finless Porpoise (Neophocaena phocaenoides)

The gut microbiome is a unique marker for cetaceans’ health status, and the microbiome composition of their skin wounds can indicate a potential infection from their habitat. Our study provides the first comparative analysis of the microbial communities from gut regions and skin wounds of an individual Indo-Pacific finless porpoise (Neophocaena phocaenoides). Microbial richness increased from the foregut to the hindgut with variation in the composition of microbes. Fusobacteria (67.51% ± 5.10%), Firmicutes (22.00% ± 2.60%), and Proteobacteria (10.47% ± 5.49%) were the dominant phyla in the gastrointestinal tract, while Proteobacteria (76.11% ± 0.54%), Firmicutes (22.00% ± 2.60%), and Bacteroidetes (10.13% ± 0.49%) were the dominant phyla in the skin wounds. The genera Photobacterium, Actinobacillus, Vibrio, Erysipelothrix, Tenacibaculum, and Psychrobacter, considered potential pathogens for mammals, were identified in the gut and skin wounds of the stranded Indo-Pacific finless porpoise. A comparison of the gut microbiome in the Indo-Pacific finless porpoise and other cetaceans revealed a possible species-specific gut microbiome in the Indo-Pacific finless porpoise. There was a significant difference between the skin wound microbiomes in terrestrial and marine mammals, probably due to habitat-specific differences. Our results show potential species specificity in the microbiome structure and a potential threat posed by environmental pathogens to cetaceans.

Rapid DNA visual detection of polymicrobial bloodstream infection using filter paper

Bloodstream infection (BSI) is a major complication in patients with cancers due to therapy-induced neutropenia and underlying conditions, which increases hospitalization time and mortality rate. Targeted and timely antimicrobial management is crucial to save the patients’ lives and reduce the social and economic burdens. Blood culture is a routine clinical diagnostic method of BSI with a long turnaround time, and generally identifies monomicrobial BSI. Thus, polymicrobial BSI often goes undetected although it occurs more frequently in these patients and results in more severe outcomes compared to monomicrobial BSI. In this work, we apply glutaric anhydride, N-hydroxysuccinimide and N,N′-dicyclohexylcarbodiimide to fabricate a functional surface on cellulose filter paper. Targeting three pathogens (Escherichia coli, Saccharomyces cerevisiae, and human cytomegalovirus) commonly occurring in BSI in neutropenic patients, we demonstrate rapid and accurate triplex pathogen DNA detection using the functionalized paper. All three pathogen DNA was identified in 1–5 min with a detection limit of 0.1–0.5 ng/µL. The developed test tool has the potential to provide rapid polymicrobial BSI diagnosis in support of timely, accurate antimicrobial treatment, and could be integrated into an automatic sample-to-result portable equipment.

The utility of extended differential parameters as a biomarker of bacteremia at a tertiary academic hospital in persons with and without HIV infection in South Africa

INTRODUCTION

Extended differential parameters (EDPs) are generated with the automated differential count by Sysmex XN-series automated hematology analysers, and include the immature granulocyte count (IG%), the neutrophil fluorescent light intensity (NE-SFL) and the neutrophil fluorescent light distribution width (NE-WY). These have been proposed as early biomarkers of bacteremia. This study aimed to evaluate the NE-SFL, NE-WY and IG% in comparison to neutrophil CD64 (nCD64) expression (as a high quality sepsis biomarker) among patients with suspected bacterial sepsis at the Chris Hani Baragwanath Academic Hospital in Johannesburg, South Africa.

METHODS

A daily search of the laboratory information system identified samples submitted for a blood culture (BC) and a concurrent full blood count (FBC). Automated differential counts using a Sysmex XN-9000 haematology analyser and neutrophil CD64 expression by flow cytometry were assessed on the residual FBC samples.

RESULTS

A total of 151 samples were collected, of which 83 were excluded due to equivocal results with regards to the presence of bacterial infection. The remaining 68 samples included 23 with bacteremia, 28 with evidence of non-bacteremic bacterial infection, 13 with no evidence of bacterial infection and 4 with Tuberculosis. HIV status was documented in 90 of the patients, with a seropositivity rate of 57.8%. The EDPs were all significantly higher among patients with bacteremia as compared to those without bacterial infection, but on ROC curve analyses, only the NE-SFL showed good performance (AUC>0.8) for discriminating cases with bacteremia from those without bacterial infection at a cut-off value of 49.75. In comparison to the nCD64, the NE-SFL showed moderate agreement (kappa = 0.5). On stratification of the ROC analysis by HIV status, the NE-SFL showed superior performance among persons with HIV infection (AUC = 1), while the automated IG% showed better performance among the patients without HIV infection (AUC = 0.9).

CONCLUSION

In this study, EDPs showed differential performance as biomarkers for bacteremia according to HIV-status in the South African setting, with the most promising results seen with the NE-SFL and IG% parameters among people with and without HIV infection, respectively. Further assessment of these parameters without pre-selection of patients likely to have infection is required to further determine their clinical utility, particularly among patients with underlying inflammatory conditions or malignancy.

Blood Bacteria-Free DNA in Septic Mice Enhances LPS-Induced Inflammation in Mice through Macrophage Response

Although bacteria-free DNA in blood during systemic infection is mainly derived from bacterial death, translocation of the DNA from the gut into the blood circulation (gut translocation) is also possible. Hence, several mouse models with experiments on macrophages were conducted to explore the sources, influences, and impacts of bacteria-free DNA in sepsis. First, bacteria-free DNA and bacteriome in blood were demonstrated in cecal ligation and puncture (CLP) sepsis mice. Second, administration of bacterial lysate (a source of bacterial DNA) in dextran sulfate solution (DSS)-induced mucositis mice elevated blood bacteria-free DNA without bacteremia supported gut translocation of free DNA. The absence of blood bacteria-free DNA in DSS mice without bacterial lysate implies an impact of the abundance of bacterial DNA in intestinal contents on the translocation of free DNA. Third, higher serum cytokines in mice after injection of combined bacterial DNA with lipopolysaccharide (LPS), when compared to LPS injection alone, supported an influence of blood bacteria-free DNA on systemic inflammation. The synergistic effects of free DNA and LPS on macrophage pro-inflammatory responses, as indicated by supernatant cytokines (TNF-α, IL-6, and IL-10), pro-inflammatory genes (NFκB, iNOS, and IL-1β), and profound energy alteration (enhanced glycolysis with reduced mitochondrial functions), which was neutralized by TLR-9 inhibition (chloroquine), were demonstrated. In conclusion, the presence of bacteria-free DNA in sepsis mice is partly due to gut translocation of bacteria-free DNA into the systemic circulation, which would enhance sepsis severity. Inhibition of the responses against bacterial DNA by TLR-9 inhibition could attenuate LPS-DNA synergy in macrophages and might help improve sepsis hyper-inflammation in some situations.

Oral mucositis: Current knowledge and future directions

Oral mucositis secondary to head and neck chemoradiation displays a complex molecular pathogenesis involving epithelial and microvascular injury, release of pro-inflammatory cytokines, and host-microbiome communications. These processes lead to oxidative stress and the release of reactive oxygen species that stifle the structural integrity of the oral mucosa, with emergence of erosions and ulcers. The consequences are malnutrition, psychological/psychiatric symptoms, poor quality of life, and occurrence of opportunistic infections. The latter pose a major challenge due to the risk of interruption of anti-neoplastic therapy, tumour recurrence and, ultimately, death. This article aims to present the clinical characteristics, molecular pathogenesis, and an overview of the predisposing factors and current management of oral mucositis. It is anticipated that the future direction of the management of oral mucositis will focus on evidence-based prehabilitation and pre- and per-chemoradiation therapy monitoring.

G-CSF as a potential early biomarker for diagnosis of bloodstream infection

Background

Cytokines play an important role in bacterial infection, and thus, we aim to find out cytokines that may be diagnostically significant in early stage of bacterial bloodstream infection.

Methods

Mice models infected with Staphylococcus aureus and Klebsiella pneumoniae were established. Then dynamic changes of nine serum cytokines were monitored within 48 hours after the infection. Cytokines with significant differences between the infected groups and control group were further analyzed. Clinical samples of patients who were suspected of bloodstream infection were collected. Then the diagnostic efficiency of screened cytokines was determined with receiver operating characteristic curve analysis.

Results

As for mice models infected by Staphylococcus aureus and Klebsiella pneumoniae, six cytokines including IL‐1β, IL‐6, IL‐12p70, G‐CSF, IFN‐γ, and TNF‐α were significantly different (P < .05) between two bacterial infected groups. As for clinical samples, three cytokines including IL‐6, IL‐12p70, and G‐CSF showed significant differences between infection group (Staphylococcus aureus and Klebsiella pneumonia group) and negative control group. With the area under curve of 0.7350 and 0.6431 for G‐CSF and IL‐6, respectively, these two cytokines were significantly different between Staphylococcus aureus and Klebsiella pneumoniae infection groups. Combination of G‐CSF and IL‐6 could improve the AUC to 0.8136.

Conclusions

G‐CSF cannot only identify bacterial bloodstream infection, but can also distinguish the infection of Staphylococcus aureus from Klebsiella pneumoniae. Further investigation should be performed concerning the diagnostic efficiency of G‐CSF in diagnosing different types of bacterial bloodstream infection.

Prevalence and predictors of bacteremia in dairy calves with diarrhea

Gastrointestinal disease is the most common cause of mortality in dairy calves. Septicemia is an important sequela of diarrhea, and the possibility of bacteremia is the primary justification for empirical antimicrobial therapy. Prior reports estimate that approximately one-third of diarrheic calves are bacteremic; however, those estimates may not be representative of routine cases in heifer calves on commercial dairy operations early in the course of disease. We hypothesized that the prevalence of bacteremia in calves with diarrhea and systemic signs of illness is less than prior estimates (~31%), and that clinical signs or hematological values would be associated with the presence or absence of bacteremia. Female calves less than 21 d of age with and without diarrhea were enrolled from 2 commercial dairy farms over a 10-wk period. Diarrheic calves were enrolled if they were newly diagnosed, had loose to watery stool, had either dehydration (assessed by skin tent and eye position) or depression (assessed by suckle reflex and standing ability), and had no prior antimicrobial treatments. Complete health assessments were conducted at 0, 7, and 14 d following enrollment. An aseptic jugular venous sample was collected and cultured using aerobic and anaerobic methods, and bacterial species were identified using mass spectrometry. Poisson regression models were used to identify associations with bacteremia and compute adjusted prevalence ratios. The prevalence of bacteremia in diarrheic and healthy calves was 9.26% (10/108, 95% confidence interval: 4.5-16%) and 14.8% (4/27, 95% confidence interval: 1.4-28.2%), respectively. Among calves with diarrhea, those with a fever (>39.7°C) or depression were 4.8 and 6.5 times more likely, respectively, to have bacteremia. Only 1 of 47 calves (2%) without signs of depression was bacteremic. The prevalence of bacteremia in diarrheic calves with signs of systemic illness (depression or dehydration) was significantly lower than previous estimates, and bacteremia was rare among calves without observed depression. Antimicrobial therapy targeting bacteremia is not currently justified in routine cases of diarrhea in preweaning calves without signs of depression. These results suggest a substantial opportunity for more targeted antimicrobial therapy to improve antimicrobial stewardship.

Pathogen clonal expansion underlies multiorgan dissemination and organ-specific outcomes during murine systemic infection

The dissemination of pathogens through blood and their establishment within organs lead to severe clinical outcomes. However, the within-host dynamics that underlie pathogen spread to and clearance from systemic organs remain largely uncharacterized. In animal models of infection, the observed pathogen population results from the combined contributions of bacterial replication, persistence, death, and dissemination, each of which can vary across organs. Quantifying the contribution of each these processes is required to interpret and understand experimental phenotypes. Here, we leveraged STAMPR, a new barcoding framework, to investigate the population dynamics of extraintestinal pathogenic Escherichia coli, a common cause of bacteremia, during murine systemic infection. We show that while bacteria are largely cleared by most organs, organ-specific clearance failures are pervasive and result from dramatic expansions of clones representing less than 0.0001% of the inoculum. Clonal expansion underlies the variability in bacterial burden between animals, and stochastic dissemination of clones profoundly alters the pathogen population structure within organs. Despite variable pathogen expansion events, host bottlenecks are consistent yet highly sensitive to infection variables, including inoculum size and macrophage depletion. We adapted our barcoding methodology to facilitate multiplexed validation of bacterial fitness determinants identified with transposon mutagenesis and confirmed the importance of bacterial hexose metabolism and cell envelope homeostasis pathways for organ-specific pathogen survival. Collectively, our findings provide a comprehensive map of the population biology that underlies bacterial systemic infection and a framework for barcode-based high-resolution mapping of infection dynamics.

Kocuria rosea Bacteremia in Chronic Kidney Disease Patient: A Rare Case Report

Kocuria sp. may cause bacteremia, peritonitis, brain abscesses, meningitis, endocarditis, and acute cholecystitis in immunocompromised individuals. Recent reports identified Kocuria rosea in bacteremia associated with in dwelling intravenous lines, continuous dialysis fluids etc. We report on the case of bacteremia caused by K.rosea, a gram-positive microorganism in a 65-year-old female with a known case of end-stage renal disease on hemodialysis. After Piperacillin and Tazobactam antibiotic treatment, the patient got cured of fever and infection. This report presents a rare case of K.rosea bacteremia successfully treated with common antibiotics. Proper identification systems should be there to know the cause of bacteremia. The bacteremia cases with rare organisms should not be ignored.

Bacterial profile, antimicrobial susceptibility patterns, and associated factors among bloodstream infection suspected patients attending Arba Minch General Hospital, Ethiopia

Bacterial bloodstream infections are of great concern globally. Of late, the emergence of drug resistant bacteria worsen the related morbidity and mortality. This study was aimed to determine the bacterial profile, antimicrobial susceptibility patterns, and associated factors among the blood stream infection (BSI) suspected patients attending the Arba Minch General Hospital (AMGH), southern Ethiopia, from 01 June through 31st August, 2020. A cross-sectional study was conducted among 225 BSI suspected patients. Systematic random sampling method was used to select patients. Blood culture was done to isolate bacterial pathogens. Antimicrobial susceptibility test was performed by employing the Kirby-Bauer disc diffusion method. Descriptive statistics and multivariable logistic regression analysis were done by Statistical Package for Social Service (SPSS) version 22. The rate of prevalence of bacteriologically confirmed cases was 22/225 (9.8%). Majority of BSI were caused by Gram-positive cocci, 13/22 (59.1%), particularly the isolates of S. aureus, 7/22 (31.8%) followed by Enterococci species, 4/22 (18.2%) and coagulase-negative Staphylococci (CoNS), 2/22 (9.1%). Among the Gram-negative bacteria 9/22 (41.1%), Klebsiella species 4/22 (18.2%) was the prominent one followed by Escherichia coli 2/22 (9.1%), Pseudomonas aeruginosa 2/22 (9.1%), and Enterobacter species 1/22 (4.5%). All the isolates of Gram-negative bacteria were susceptible to meropenem whereas 69.2% of the isolates of Gram-positive counterparts were susceptible to erythromycin. Slightly above two third (68.2%) of the total isolates were multidrug resistant. Insertion of a peripheral intravenous line was significantly associated with BSI [p = 0.03; Adjusted Odds Ratio = 4.82; (Confidence Interval: 1.08-21.46)]. Overall results revealed that eventhough the prevalence of BSI in Arba Minch is comparatively lower (9.8%), multidrug resistance is alarmingly on the rise, which is to be addressed through effective surveillance and control strategies.

Bacterial and fungal bloodstream infections in solid organ transplant recipients: results from a Danish cohort with nationwide follow-up

OBJECTIVES

Bloodstream infections (BSI) are prevalent after solid organ transplantation (SOT). In this study, we aimed to investigate the incidence and risk factors for BSI in the first 5 years post-transplantation.

METHODS

The study included 1322 SOT (kidney, liver, lung and heart) recipients transplanted from 2010 to 2017 with a total of 5616 years of follow-up. Clinical characteristics and microbiology were obtained from the Centre of Excellence for Personalized Medicine of Infectious Complications in Immune Deficiency (PERSIMUNE) data repository with nationwide follow-up. Incidence was investigated in the different SOT groups. Risk factors associated with BSI were assed in the combined group in time-updated multivariable Cox regressions.

RESULTS

The cumulative incidence of first BSI in the first 5 years post-transplantation differed in the SOT groups with a lower incidence in heart transplant recipients than in the other SOT groups (heart: 4.4%, CI 0.0-9.7%, vs. kidney: 24.6%, CI 20.9-28.2%, liver: 24.7%, CI 19.4-29.9%, and lung: 19.6%, CI 14.5-24.8%, p <0.001). Age above 55 years (HR 1.71, CI 1.2-2.4, p=0.002) and higher Charlson comorbidity index score (HR per unit increase: 1.25, CI 1.1-1.4, p<0.001) at transplantation, current cytomegalovirus (CMV) infection (HR 4.5, CI 2.6-7.9, p<0.001) and current leucopenia (HR 13.3, CI 3.7-47.9, p<0.001) were all associated with an increased risk of BSI.

CONCLUSION

In SOT recipients, the incidence of BSI differed with the type of transplanted organ. Risk of BSI was higher in older recipients and in recipients with comorbidity, current CMV infection or leucopenia. Thus, increased attention towards BSI in recipients with these characteristics is warranted.

Genomic epidemiology of methicillin-resistant and -susceptible Staphylococcus aureus from bloodstream infections

Background

Bloodstream infections due to Staphylococcus aureus cause significant patient morbidity and mortality worldwide. Of major concern is the emergence and spread of methicillin-resistant S. aureus (MRSA) in bloodstream infections, which are associated with therapeutic failure and increased mortality.

Methods

We generated high quality draft genomes from 323 S. aureus blood culture isolates from patients diagnosed with bloodstream infection at the Dartmouth-Hitchcock Medical Center, New Hampshire, USA in 2010–2018.

Results

In silico detection of antimicrobial resistance genes revealed that 133/323 isolates (41.18%) carry horizontally acquired genes conferring resistance to at least three antimicrobial classes, with resistance determinants for aminoglycosides, beta-lactams and macrolides being the most prevalent. The most common resistance genes were blaZ and mecA, which were found in 262/323 (81.11%) and 104/323 (32.20%) isolates, respectively. Majority of the MRSA (102/105 isolates or 97.14%) identified using in vitro screening were related to two clonal complexes (CC) 5 and 8. The two CCs emerged in the New Hampshire population at separate times. We estimated that the time to the most recent common ancestor of CC5 was 1973 (95% highest posterior density (HPD) intervals: 1966–1979) and 1946 for CC8 (95% HPD intervals: 1924–1959). The effective population size of CC8 increased until the late 1960s when it started to level off until late 2000s. The levelling off of CC8 in 1968 coincided with the acquisition of SCCmec Type IV in majority of the strains. The plateau in CC8 also coincided with the acceleration in the population growth of CC5 carrying SCCmec Type II in the early 1970s, which eventually leveled off in the early 1990s. Lastly, we found evidence for frequent recombination in the two clones during their recent clonal expansion, which has likely contributed to their success in the population.

Conclusions

We conclude that the S. aureus population was shaped mainly by the clonal expansion, recombination and co-dominance of two major MRSA clones in the last five decades in New Hampshire, USA. These results have important implications on the development of effective and robust strategies for intervention, control and treatment of life-threatening bloodstream infections.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-06293-3.

Multifunctional lipid-based nanocarriers with antibacterial and anti-inflammatory activities for treating MRSA bacteremia in mice

Background

Bacteremia-induced sepsis is a leading cause of mortality in intensive care units. To control a bacterial infection, an immune response is required, but this response might contribute to organ failure. Kidneys are one of the main organs affected by bacteremia. Combination therapies with antibacterial and anti-inflammatory effects may be beneficial in treating bacteremia. This study aimed to develop nanostructured lipid carriers (NLCs) loaded with ciprofloxacin and rolipram that exert a combination of anti-methicillin-resistant Staphylococcus aureus (MRSA) and anti-inflammatory effects. Retinol was incorporated into the nanoparticles to transport retinol-binding protein 4 (RBP4) to the kidneys, which abundantly express RBP receptors. The NLCs were fabricated by high-shear homogenization and sonication, and neutrophils were used as a model to assess their anti-inflammatory effects. Mice were injected with MRSA to establish a model of bacteremia with organ injury.

Results

The mean nanoparticle size and zeta potential of the NLCs were 171 nm and − 39 mV, respectively. Ciprofloxacin (0.05%, w/v) and rolipram (0.02%) achieved encapsulation percentages of 88% and 96%, respectively, in the nanosystems. The minimum bactericidal concentration of free ciprofloxacin against MRSA increased from 1.95 to 15.63 µg/ml when combined with rolipram, indicating a possible drug-drug interaction that reduced the antibacterial effect. Nanoparticle inclusion promoted the anti-MRSA activity of ciprofloxacin according to time-kill curves. The NLCs were found to be largely internalized into neutrophils and exhibited superior superoxide anion inhibition than free drugs. Retinol incorporation into the nanocarriers facilitated their efficient targeting to the kidneys. The NLCs significantly mitigated MRSA burden and elastase distribution in the organs of MRSA-infected animals, and the greatest inhibition was observed in the kidneys. Bacterial clearance and neutrophil infiltration suppression attenuated the bacteremia-induced cytokine overexpression, leading to an improvement in the survival rate from 22% to 67%.

Conclusions

The dual role of our NLCs endowed them with greater efficacy in treating MRSA bacteremia than that of free drugs.

Serum N-Glycomics Stratifies Bacteremic Patients Infected with Different Pathogens

Bacteremia—i.e., the presence of pathogens in the blood stream—is associated with long-term morbidity and is a potential precursor condition to life-threatening sepsis. Timely detection of bacteremia is therefore critical to reduce patient mortality, but existing methods lack precision, speed, and sensitivity to effectively stratify bacteremic patients. Herein, we tested the potential of quantitative serum N-glycomics performed using porous graphitized carbon liquid chromatography tandem mass spectrometry to stratify bacteremic patients infected with Escherichia coli (n = 11), Staphylococcus aureus (n = 11), Pseudomonas aeruginosa (n = 5), and Streptococcus viridans (n = 5) from healthy donors (n = 39). In total, 62 N-glycan isomers spanning 41 glycan compositions primarily comprising complex-type core fucosylated, bisecting N-acetylglucosamine (GlcNAc), and α2,3-/α2,6-sialylated structures were profiled across all samples using label-free quantitation. Excitingly, unsupervised hierarchical clustering and principal component analysis of the serum N-glycome data accurately separated the patient groups. P. aeruginosa-infected patients displayed prominent N-glycome aberrations involving elevated levels of fucosylation and bisecting GlcNAcylation and reduced sialylation relative to other bacteremic patients. Notably, receiver operating characteristic analyses demonstrated that a single N-glycan isomer could effectively stratify each of the four bacteremic patient groups from the healthy donors (area under the curve 0.93–1.00). Thus, the serum N-glycome represents a new hitherto unexplored class of potential diagnostic markers for bloodstream infections.

Antimicrobial susceptibility patterns of bacteria that commonly cause bacteremia at a tertiary hospital in Zambia

Background: Bloodstream infections and antimicrobial resistance cause global increases in morbidity and mortality. Aim: We evaluated the antimicrobial susceptibility patterns of bacteria that commonly cause bacteremia in humans. Materials & methods: We conducted a retrospective cross-sectional study at the University Teaching Hospitals in Lusaka, Zambia, using Laboratory Information Systems. Results: The commonest isolated bacteria associated with sepsis were Klebsiella pneumoniae. The distribution of bacteria associated with bacteremia in different wards and departments pneumonia. The distribution of bacteria associated with bacteremia in different wards and departments at University Teaching Hospitals was were statistically significant (χ2 = 1211.518; p < 0.001). Conclusion: K. pneumoniae, Escherichia coli, Pantoea agglomerans and Enterococcus species have developed high resistance levels against ampicillin, cefotaxime, ciprofloxacin, gentamicin and trimethoprim/sulfamethoxazole and a very low resistance levels against imipenem and Amikacin.

Etomidate Use for Rapid Sequence Intubation Is Not Associated With Nosocomial Infection

INTRODUCTION

Etomidate is commonly used for induction of anesthesia for rapid sequence intubation (RSI). It has little impact on hemodynamic status, making it a widely used agent. Due to the inhibition of cortisol production, etomidate causes adrenal suppression. The purpose of this study is to determine whether there is a correlation with etomidate use and the incidence of secondary infections.

METHODS

This was a retrospective cohort of hospitalized patients who received either etomidate or control (ketamine, propofol, or no agent) for RSI. The primary endpoint was the incidence of secondary infections. Secondary outcomes included number of mechanical ventilator-free days within 28 days, 30-day mortality, length of hospital stay, and length of intensive care unit stay.

RESULTS

A total of 434 patients were reviewed, of which 129 (29.7%) met the study criteria (n = 94 etomidate; n = 35 control). The incidence of secondary infection was numerically higher in the etomidate group compared with the control group, though this was not statistically significant (38.7% vs. 28.6%, p = 0.447). Also, though the secondary outcomes showed no statistically significant difference between the groups, the patients in the control group had a longer hospital stay (14.0 vs. 18.1, p = 0.20) and a longer ICU stay (11.0 vs. 14.1, p = 030). Furthermore, the etomidate group had a non-statistically significant higher incidence of bacteremia (8 vs. 0, p = 0.17).

CONCLUSION

The use of etomidate was not associated with increased incidence of secondary infection. To fully understand the effects of etomidate use and its subsequent adrenal suppression, larger studies are needed.

Utility of procalcitonin as an early diagnostic marker of bacteremia in individuals with periodontitis Stage II and III

BACKGROUND

The aim of the present study is to assess the ability of procalcitonin (PCT) to differentiate between periodontal health and Stage II and III periodontitis. We further assessed, if PCT can reflect early bacteremia induced by non-surgical periodontal treatment (NSPT).

METHODS

Sixty-four systemically healthy individuals were divided into Group I, periodontally healthy, and Group II, Stage II and III periodontitis. NSPT was done for both the groups. Standardized serum and salivary samples were obtained and analyzed for PCT levels using highly sensitive double antibody sandwich enzyme-linked immunosorbent assay at baseline and 2 weeks. In addition, the serum levels of PCT were recorded at immediate and 1-hour post-NSPT.

RESULTS

Mean PCT levels (saliva = 0.03 ng/mL and serum = 0.05 ng/mL) in periodontally healthy group were considerably lower than that in the periodontitis group (saliva = 0.22 ng/mL and serum = 1.85 ng/mL) with significant intergroup comparison at P < 0.001. Post NSPT the mean serum PCT values increased from 1.854 ng/mL to 1.871 ng/mL at the immediate interval and remained at 0.879 ng/mL after 2 weeks at P < 0.001. Spearman correlation showed highly significant positive correlation between serum and salivary PCT values to clinical attachment level (CAL) at P < 0.001 and rho = 0.78 and 0.75, respectively. Linear regression model showed serum PCT to be a significant predictor for CAL.

CONCLUSION

Screening for serum PCT levels in patients with periodontitis could act not only as a guide to assess the bacterial load and use of antibiotics but also as a predictor for CAL loss in patients with periodontitis.

Correlation of procalcitonin to positive blood culture results in a sample of South African trauma ICU patients between 2016 and 2017

PURPOSE

This study sought to investigate the screening accuracy of procalcitonin (PCT) for bacteremia, as defined by a positive blood culture, in a South African trauma ICU.

METHODS

This was a retrospective chart review study involving 149 patients who were admitted to the ICU of a level-1 trauma center in South Africa between 2016 and 2017. Median PCT levels in patients with and without positive blood cultures were compared. The screening accuracy of PCT for a positive blood culture was summarized as sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). Two PCT cut-points were investigated: a general cut-point in the South African context (> 2.0 ng/mL), and a trauma ICU-specific cut-point (prioritizing specificity while optimizing sensitivity) which was determined from a receiver-operator-characteristic curve.

RESULTS

Bacteremic patients had higher median PCT levels when compared with non-bacteremic patients (30.5 ng/mL versus 6.6 ng/mL, p = 0.002). The sensitivity, specificity, PPV, and NPV of PCT > 2.0 ng/mL was 86% (95% confidence interval-CI 71-94%), 29% (CI 22-38%), 28% (CI 20-37%), and 87% (CI 73-94%), respectively. The unit-specific cut-point was PCT > 31.0 ng/mL, which had a sensitivity, specificity, PPV, and NPV of 50% (CI 34-66%), 80% (CI 71-86%), 44% (CI 30-59%), and 83% (CI 75-89%), respectively. Unlike PCT > 2.0 ng/mL, PCT > 31.0 ng/mL demonstrated fair-to-good test specificity in a sub-analysis of patients who underwent recent surgery.

CONCLUSIONS

Increased PCT levels were associated with bacteremia in this study. PCT > 31.0 ng/mL may be used to rule in suspected bacteremia in this trauma ICU setting.

Antimicrobial resistance of bacteraemia in the emergency department of a German university hospital (2013-2018): potential carbapenem-sparing empiric treatment options in light of the new EUCAST recommendations

Background

This study investigated predominant microorganisms causing community-onset bacteraemia at the medical emergency department (ED) of a tertiary-care university hospital in Germany from 2013 to 2018 and their antimicrobial susceptibility patterns.

Methods

Antimicrobial resistance patterns in patients with positive blood cultures presenting to an internal medicine ED were retrospectively analysed.

Results

Blood cultures were obtained at 5191 of 66,879 ED encounters, with 1013 (19.5%) positive results, and true positive results at 740 encounters (diagnostic yield, 14.3%). The most frequently isolated relevant microorganisms were Enterobacterales (n = 439, 59.3%), Staphylococcus aureus (n = 92, 12.4%), Streptococcus pneumoniae (n = 34, 4.6%), Pseudomonas aeruginosa (n = 32, 4.3%), Streptococcus pyogenes (n = 16, 2.2%), Enterococcus faecalis (n = 18, 2.4%), and Enterococcus faecium (n = 12, 1.6%). Antimicrobial susceptibility testing revealed a high proportion of resistance against ampicillin-sulbactam in Enterobacterales (42.2%). The rate of methicillin-resistant Staphylococcus aureus was low (0.4%).

Piperacillin-tazobactam therapy provided coverage for 83.2% of all relevant pathogens using conventional breakpoints. Application of the new European Committee on Antimicrobial Susceptibility Testing (EUCAST) recommendations increased the percentage of susceptible isolates to high-dose piperacillin-tazobactam to 92.8% (p < 0.001). Broad-spectrum carbapenems would only cover an additional 4.8%. The addition of vancomycin or linezolid extended coverage by just 1.7%.

Conclusions

Using an ureidopenicillin-beta-lactamase inhibitor combination at the high dose suggested by the new EUCAST recommendations provided nearly 93% coverage for relevant pathogens in patients with suspected bloodstream infection in our cohort. This might offer a safe option to reduce the empiric use of carbapenems. Our data support the absence of a general need for glycopeptides or oxazolidinones in empiric treatment.

Plasma interleukin-6 concentration for the diagnosis of sepsis in critically ill adults

BACKGROUND

The definition of sepsis has evolved over time, along with the clinical and scientific knowledge behind it. For years, sepsis was defined as a systemic inflammatory response syndrome (SIRS) in the presence of a documented or suspected infection. At present, sepsis is defined as a life-threatening organ dysfunction resulting from a dysregulated host response to infection. Even though sepsis is one of the leading causes of mortality in critically ill patients, and the World Health Organization (WHO) recognizes it as a healthcare priority, it still lacks an accurate diagnostic test. Determining the accuracy of interleukin-6 (IL-6) concentrations in plasma, which is proposed as a new biomarker for the diagnosis of sepsis, might be helpful to provide adequate and timely management of critically ill patients, and thus reduce the morbidity and mortality associated with this condition.

OBJECTIVES

To determine the diagnostic accuracy of plasma interleukin-6 (IL-6) concentration for the diagnosis of bacterial sepsis in critically ill adults.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, LILACS, and Web of Science on 25 January 2019. We screened references in the included studies to identify additional studies. We did not apply any language restriction to the electronic searches.

SELECTION CRITERIA

We included diagnostic accuracy studies enrolling critically ill adults aged 18 years or older under suspicion of sepsis during their hospitalization, where IL-6 concentrations were evaluated by serological measurement.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened the references to identify relevant studies and extracted data. We assessed the methodological quality of studies using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool. We estimated a summary receiver operating characteristic (SROC) curve by fitting a hierarchical summary ROC (HSROC) non-linear mixed model. We explored sources of heterogeneity using the HSROC model parameters. We conducted all analyses in the SAS statistical software package and R software.

MAIN RESULTS

We included 23 studies (n = 4192) assessing the accuracy of IL-6 for the diagnosis of sepsis in critically ill adults. Twenty studies that were available as conference proceedings only are awaiting classification. The included participants were heterogeneous in terms of their distribution of age, gender, main diagnosis, setting, country, positivity threshold, sepsis criteria, year of publication, and origin of infection, among other factors. Prevalence of sepsis greatly varied across studies, ranging from 12% to 78%. We considered all studies to be at high risk of bias due to issues related to the index test domain in QUADAS-2. The SROC curve showed a great dispersion in individual studies accuracy estimates (21 studies, 3650 adult patients), therefore the considerable heterogeneity in the collected data prevented us from calculating formal accuracy estimates. Using a fixed prevalence of sepsis of 50% and a fixed specificity of 74%, we found a sensitivity of 66% (95% confidence interval 60 to 72). If we test a cohort 1000 adult patients under suspicion of sepsis with IL-6, we will find that 330 patients would receive appropriate and timely antibiotic therapy, while 130 patients would be wrongly considered to have sepsis. In addition, 370 out of 1000 patients would avoid unnecessary antibiotic therapy, and 170 patients would have been undiagnosed of sepsis. This numerical approach should be interpreted with caution due to the limitations described above.

AUTHORS' CONCLUSIONS

Our evidence assessment of plasma interleukin-6 concentrations for the diagnosis of sepsis in critically ill adults reveals several limitations. High heterogeneity of collected evidence regarding the main diagnosis, setting, country, positivity threshold, sepsis criteria, year of publication, and the origin of infection, among other factors, along with the potential number of misclassifications, remain significant constraints for its implementation. The 20 conference proceedings assessed as studies awaiting classification may alter the conclusions of the review once they are fully published and evaluated. Further studies about the accuracy of interleukin-6 for the diagnosis of sepsis in adults that apply rigorous methodology for conducting diagnostic test accuracy studies are needed. The conclusions of the review will likely change once the 20 studies pending publication are fully published and included.

Bacteremia after professional mechanical plaque removal in patients with chronic periodontitis

OBJECTIVE

The aim of this study was to investigate the characteristics of bacteremia caused by professional mechanical plaque removal (PMPR) in two groups of patients with generalized moderate chronic periodontitis.

MATERIALS AND METHODS

Venous blood samples were taken at multiple time points for one hour following PMPR in fifty patients with generalized moderate chronic periodontitis. Subjects consisted of two groups, one group was receiving supportive periodontal therapy (SPT, n = 25) and the other group was receiving initial periodontal therapy (IPT, n = 25). Blood samples were processed and analyzed for cultivable microflora. Pertinent clinical parameters were recorded for each patient in both groups.

RESULTS

Bacteremia was detected in 10 of 25 SPT and 8 of 25 IPT patients (p = 0.796). In both groups, the prevalence of bacteremia was dependent on the time of blood sampling and varied in magnitude between <10²  CFU/ml and 10⁶  CFU/ml. Sixteen different bacterial species were identified in both groups, mostly Actinomyces naeslundii (SPT n = 3, IPT n = 4) and Streptococcus spp. (SPT n = 6, IPT n = 2). In regression models, Grade II furcation involvement (p = 0.004) and Gingival Bleeding Index (p = 0.036) had affected the occurrence of bacteremia but in the SPT group only.

CONCLUSION

Professional mechanical plaque removal was associated with bacteremia regardless of whether a patient was receiving SPT or IPT.

In Vivo Pharmacokinetic/Pharmacodynamic Profiles of Danofloxacin in Rabbits Infected With Salmonella typhimurium After Oral Administration

Salmonella typhimurium is a highly transmissible pathogen in rabbits that causes significant losses. Danofloxacin shows excellent efficacy against S. typhimurium infections. However, there are few reports of the pharmacokinetic/pharmacodynamic (PK/PD) modeling of danofloxacin against this pathogen. The aim of this study was to evaluate the in vivo PK/PD relationship of danofloxacin in rabbits infected with S. typhimurium. We used the reduction of bacterial burden in the blood, liver, spleen, and lung as the target PD endpoints, and determined the PK/PD indexes that best correlated with the efficacy and its corresponding magnitude. Danofloxacin was administrated orally to experimentally S. typhimurium-infected rabbits once daily for three successive days. The concentrations of danofloxacin in the serum and the bacterial burden in the blood, liver, spleen, and lung were determined. The PK/PD relationships of danofloxacin against S. typhimurium were evaluated using a Sigmoid E_max model. The results showed that the area under the concentration-time curve from 0 to 24 h/minimum inhibitory concentration (AUC_{24 h}/MIC) ratio correlated well with the in vivo antibacterial effectiveness in different organs, with an r² of 0.8971, 0.9186, 0.9581, and 0.8708 in the blood, liver, spleen, and lung, respectively. The AUC_{24 h}/MIC ratios for the bactericidal effect (3 × Log₁₀ colony forming units/mL reductions) were 121.30, 354.28, 216.64, and 228.66 in the blood, liver, spleen, and lung, respectively, indicating that the in vivo effectiveness of danofloxacin against S. typhimurium using bacterial reduction in different organs as PD endpoints was not identical. This study illustrated that the selection of the target organ for bacterial reduction determination had little effect on best PK/PD parameter determination, but is critical for parameter magnitude calculation in antimicrobial PK/PD modeling, and furthermore, has an impact on the rational dosage optimization process.

Chronic osteomyelitis of the tibia in a runner: catastrophic consequences of shin splints

Medial tibial stress syndrome and chronic osteomyelitis are conditions that are traditionally thought to affect very different patient groups. We present a case of shin splints in a recreational long-distance runner, complicated by chronic osteomyelitis of the tibia. This is a unique case in which the microtrauma resulting from shin splints was implicated as an entry point for bacterial infection into the bone. Clinical evaluation and bone biopsy culture results indicated haematogenous spread of bacteria originating from the oral cavity. The patient required surgical resection of the affected bone and a prolonged course of intravenous antibiotic treatment. We illustrate that when shin splints show signs of acute inflammation with delayed recovery, the possibility of osteomyelitis should be kept in mind.

Linezolid and atorvastatin impact on pneumonia caused by Staphyloccocus aureus in rabbits with or without mechanical ventilation

Pneumonia may involve methicillin-resistant Staphylococcus aureus (MRSA), with elevated rates of antibiotics failure. The present study aimed to assess the effect of statins given prior to pneumonia development. Spontaneously breathing (SB) or mechanically ventilated (MV) rabbits with pneumonia received atorvastatin alone, linezolid (LNZ) alone, or a combination of both (n = 5 in each group). Spontaneously breathing and MV untreated infected animals (n = 11 in each group), as well as uninfected animals (n = 5 in each group) were used as controls. Microbiological features and inflammation were evaluated. Data are presented as medians (interquartile range). Linezolid alone tended to reduce pulmonary MRSA load in both SB and MV rabbits, but failed to prevent bacteremia (59%) in the latter. Linezolid alone dampened TNF-α lung production in both SB and MV rabbits (e.g., 2226 [789] vs. 11478 [10251] pg/g; p = 0.022). Statins alone did the same in both SB and MV animals (e.g., 2040 [133]; p = 0.016), and dampened systemic inflammation in the latter, possibly through TLR2 down-regulation within the lung. However, the combination of LNZ and statin led to an increased rate of bacteremia in MV animals up to 75%. Statins provide an anti-inflammatory effect in rabbits with MRSA pneumonia, especially in MV ones. However, dampening the systemic inflammatory response with statins could impede blood defenses against MRSA.

Bloodstream Infections

Bacteremia and sepsis are conditions associated with high mortality and are of great impact to health care operations. Among the top causes of mortality in the United States, these conditions cause over 600 fatalities each day. Empiric, broad-spectrum treatment is a common but often a costly approach that may fail to effectively target the correct microbe, may inadvertently harm patients via antimicrobial toxicity or downstream antimicrobial resistance. To meet the diagnostic challenges of bacteremia and sepsis, laboratories must understand the complexity of diagnosing and treating septic patients, in order to focus on creating algorithms that can help direct a more targeted approach to antimicrobial therapy and synergize with existing clinical practices defined in new Surviving Sepsis Guidelines. Significant advances have been made in improving blood culture media; as yet no molecular or antigen-based method has proven superior for the detection of bacteremia in terms of limit of detection. Several methods for rapid molecular identification of pathogens from blood cultures bottles are available and many more are on the diagnostic horizon. Ultimately, early intervention by molecular detection of bacteria and fungi directly from whole blood could provide the most patient benefit and contribute to tailored antibiotic coverage of the patient early on in the course of the disease. Although blood cultures remain as the best means of diagnosing bacteremia and candidemia, complementary testing with antigen tests, microbiologic investigations from other body sites, and histopathology can often aid in the diagnosis of disseminated disease, and application of emerging nucleic acid test methods and other new technology may greatly impact our ability to bacteremic and septic patients, particularly those who are immunocompromised.

The Level of Oxidative Neutrophil Response When Determining Endotoxin Activity Assay: A New Biomarker for Defining the Indications and Effectiveness of Intensive Care in Patients with Sepsis

Background. To analyse the clinical informativity of the neutrophil oxidative response level (“Response”) during an Endotoxin Activity Assay (EAA) as a new biomarker defining the indications and effectiveness of intensive care in cardiac surgical patients with septic complications. Methods. Blood samples were taken from 198 adult patients who were admitted to the ICU after cardiac surgery (SIRS: 34, MODS: 36, and sepsis: 128). The composite of laboratory studies included CRP, PCT, EAA with “Response” level, and presepsin. Results. 83% of patients had a “normal” neutrophil response, 12% of patients had a low neutrophil response, and 5% of patients had a critically low neutrophil response. Patients with critically low responses had the lowest values of the EAA and the highest concentrations of PSP and D-dimer (p < 0.05). Conclusions. EAA results should be interpreted with the level of neutrophil response. “Response” > 0.5 has a negative predictive value; the EAA < 0.6 at “Response” < 0.5 may indicate a high level of endotoxaemia.

Host and Pathogen Biomarkers for Severe Pseudomonas aeruginosa Infections

Pseudomonas aeruginosa is among the leading causes of severe nosocomial infections, particularly affecting critically ill and immunocompromised patients. Here we review the current knowledge on the factors underlying the outcome of P. aeruginosa nosocomial infections, including aspects related to the pathogen, the host, and treatment. Intestinal colonization and previous use of antibiotics are key risk factors for P. aeruginosa infections, whereas underlying disease, source of infection, and severity of acute presentation are key host factors modulating outcome; delayed adequate antimicrobial therapy is also independently associated with increased mortality. Among pathogen-related factors influencing the outcome of P. aeruginosa infections, antibiotic resistance, and particularly multidrug-resistant profiles, is certainly of paramount relevance, given its obvious effect on the chances of appropriate empirical therapy. However, the direct impact of antibiotic resistance in the severity and outcomes of P. aeruginosa infections is not yet well established. The interplay between antibiotic resistance, virulence, and the concerning international high-risk clones (such as ST111, ST175, and ST235) still needs to be further analyzed. On the other hand, differential presence or expression of virulence factors has been shown to significantly impact disease severity and mortality. The likely more deeply studied P. aeruginosa virulence determinant is the type III secretion system (T3SS); the production of T3SS cytotoxins, and particularly ExoU, has been well established to determine a worse outcome both in respiratory and bloodstream infections. Other relevant pathogen-related biomarkers of severe infections include the involvement of specific clones or O-antigen serotypes, the presence of certain horizontally acquired genomic islands, or the expression of other virulence traits, such as the elastase. Finally, recent data suggest that host genetic factors may also modulate the severity of P. aeruginosa infections.

Mechanical Ventilation Alters the Development of Staphylococcus aureus Pneumonia in Rabbit

Ventilator-associated pneumonia (VAP) is common during mechanical ventilation (MV). Beside obvious deleterious effects on muco-ciliary clearance, MV could adversely shift the host immune response towards a pro-inflammatory pattern through toll-like receptor (TLRs) up-regulation. We tested this hypothesis in a rabbit model of Staphylococcus aureus VAP. Pneumonia was caused by airway challenge with S. aureus, in either spontaneously breathing (SB) or MV rabbits (n = 13 and 17, respectively). Pneumonia assessment regarding pulmonary and systemic bacterial burden, as well as inflammatory response was done 8 and 24 hours after S. aureus challenge. In addition, ex vivo stimulations of whole blood taken from SB or MV rabbits (n = 7 and 5, respectively) with TLR2 agonist or heat-killed S. aureus were performed. Data were expressed as mean±standard deviation. After 8 hours of infection, lung injury was more severe in MV animals (1.40±0.33 versus [vs] 2.40±0.55, p = 0.007), along with greater bacterial concentrations (6.13±0.63 vs. 4.96±1.31 colony forming units/gram, p = 0.002). Interleukin (IL)-8 and tumor necrosis factor (TNF)-αserum concentrations reached higher levels in MV animals (p = 0.010). Whole blood obtained from MV animals released larger amounts of cytokines if stimulated with TLR2 agonist or heat-killed S. aureus (e.g., TNF-α: 1656±166 vs. 1005±89; p = 0.014). Moreover, MV induced TLR2 overexpression in both lung and spleen tissue. MV hastened tissue injury, impaired lung bacterial clearance, and promoted a systemic inflammatory response, maybe through TLR2 overexpression.

Use of Glucocorticoids and Risk of Community-Acquired Staphylococcus aureus Bacteremia: A Population-Based Case-Control Study

OBJECTIVE

To investigate whether the use of systemic glucocorticoids is a risk factor for community-acquired Staphylococcus aureus bacteremia (CA-SAB).

PATIENTS AND METHODS

We used population-based medical registries in Northern Denmark to conduct a case-control study including all adults with first-time CA-SAB and matched population controls from January 1, 2000, through December 31, 2011. Glucocorticoid users were categorized as current users (new or long-term use), former users, and nonusers. Using conditional logistic regression, we computed odds ratios (ORs) of CA-SAB according to glucocorticoid exposure, overall and by 90-day prednisolone-equivalent cumulative dose.

RESULTS

We identified 2638 patients with first-time CA-SAB and 26,379 matched population controls. Current glucocorticoid users experienced considerably increased risk of CA-SAB compared with nonusers (adjusted OR=2.48; 95% CI, 2.12-2.90). The adjusted OR was 2.73 (95% CI, 2.17-3.45) in new users, 2.31 (95% CI, 1.90-2.82) in long-term users, and much lower at 1.33 (95% CI, 0.98-1.81) in former users of glucocorticoids compared with nonusers. The risk of CA-SAB increased with higher 90-day cumulative doses. Compared with nonusers of glucocorticoids, the adjusted OR was 1.32 (95% CI, 1.01-1.72) for persons with a cumulative dose of 150 mg or less, 2.42 (95% CI, 1.76-3.33) for persons whose cumulative dose was greater than 500 to 1000 mg, and 6.25 (95% CI, 4.74-8.23) for persons with a cumulative dose greater than 1000 mg.

CONCLUSION

Glucocorticoid use was associated with a substantially increased risk of CA-SAB. The risk increased with higher cumulative dose, revealing a distinct dose-response relation.

Integrating Antimicrobial Therapy with Host Immunity to Fight Drug-Resistant Infections: Classical vs. Adaptive Treatment

Antimicrobial resistance of infectious agents is a growing problem worldwide. To prevent the continuing selection and spread of drug resistance, rational design of antibiotic treatment is needed, and the question of aggressive vs. moderate therapies is currently heatedly debated. Host immunity is an important, but often-overlooked factor in the clearance of drug-resistant infections. In this work, we compare aggressive and moderate antibiotic treatment, accounting for host immunity effects. We use mathematical modelling of within-host infection dynamics to study the interplay between pathogen-dependent host immune responses and antibiotic treatment. We compare classical (fixed dose and duration) and adaptive (coupled to pathogen load) treatment regimes, exploring systematically infection outcomes such as time to clearance, immunopathology, host immunization, and selection of resistant bacteria. Our analysis and simulations uncover effective treatment strategies that promote synergy between the host immune system and the antimicrobial drug in clearing infection. Both in classical and adaptive treatment, we quantify how treatment timing and the strength of the immune response determine the success of moderate therapies. We explain key parameters and dimensions, where an adaptive regime differs from classical treatment, bringing new insight into the ongoing debate of resistance management. Emphasizing the sensitivity of treatment outcomes to the balance between external antibiotic intervention and endogenous natural defenses, our study calls for more empirical attention to host immunity processes.

Host genetic diversity influences the severity of Pseudomonas aeruginosa pneumonia in the Collaborative Cross mice

BACKGROUND

Pseudomonas aeruginosa is one of the top three causes of opportunistic infections in humans. Patients with a compromised immune system, due to immunosuppressive therapies or underlying diseases such as cancer, AIDS or the hereditary disease cystic fibrosis, are at risk of developing P. aeruginosa infection. However, clinical evidence indicates extremely variable outcomes of P. aeruginosa infections in individuals at risk, suggesting that host multi-complex genetic traits may influence the severity of this opportunistic infection. Here, we have used an innovative experimental model to dissect whether host genetic background, such as those found in the outbred population, could influence the risk of morbidity and mortality to P. aeruginosa pneumonia.

RESULTS

A highly genetically-diverse mouse resource population, Collaborative Cross (CC) mice, was infected with a clinical strain of P. aeruginosa and subsequently monitored for mortality, mean survival time, and morbidity, change in body weight for seven days post infection. Disease phenotypes ranged from complete resistance and recovery of body weight to lethal disease. Initial variables, including body weight, age and gender, have limited influence on P. aeruginosa outcome, emphasizing the role of host genetic background in defining the risk of morbidity and mortality. When broad-sense heritability of phenotypic traits was evaluated, it confirmed the influence of genetic profile rather than environmental factors among the CC lines during P. aeruginosa infection.

CONCLUSION

This innovative model system can potentially reproduce the variables responses of disease severity observed in humans during P. aeruginosa pneumonia. Our results demonstrated that a widely-marked differential response to P. aeruginosa airway infection in term of morbidity and mortality, is mainly affected by host genetic factors, as multiple genetic loci or polymorphic variations.

Is the developmentally immature immune response in paediatric sepsis a recapitulation of immune tolerance?

Immunologically immature neonates suffer the highest incidence of paediatric sepsis. Postnatal immunological maturation is characterized by a relatively hypo-inflammatory immune response. The mechanisms that differentiate the mature and immature immune responses resemble those that differentiate the hyper- and hypo-inflammatory responses in severe sepsis. Immunological maturational differences likely affect the neonate's ability to mount an appropriate hyper-inflammatory response, a counteractive hypo-inflammatory response, and subsequent return to immune system homeostasis. To better understand the role of the hypo-inflammatory response in paediatric sepsis, we will explore the maturation of the immune system and the effect it may have on the sepsis-induced hypo-inflammatory response.

Focused ultrasound treatment of abscesses induced by methicillin resistant Staphylococcus aureus: feasibility study in a mouse model

PURPOSE

To study the therapeutic effect of focused ultrasound on abscesses induced by methicillin-resistant Staphylococcus aureus (MRSA). MRSA is a major nosocomial pathogen where immunocompromised patients are prone to develop infections that are less and less responsive to regular treatments. Because of its capability to induce a rise of temperature at a very precise location, the use of focused ultrasound represents a considerable opportunity for therapy of localized MRSA-related infections.

METHODS

50 μl of MRSA strain USA400 bacteria suspension at a concentration of 1.32 ± 0.5 × 10(5) colony forming units (cfu)/μl was injected subcutaneously in the left flank of BALB/c mice. An abscess of 6 ± 2 mm in diameter formed after 48 h. A transducer operating at 3 MHz with a focal length of 50 mm and diameter of 32 mm was used to treat the abscess. The focal point was positioned 2 mm under the skin at the abscess center. Forty-eight hours after injection four ultrasound exposures of 9 s each were applied to each abscess under magnetic resonance imaging guidance. Each exposure was followed by a 1 min pause. These parameters were based on preliminary experiments to ensure repetitive accurate heating of the abscess. Real-time estimation of change of temperature was done using water-proton resonance frequency and a communication toolbox (matMRI) developed inhouse. Three experimental groups of animals each were tested: control, moderate temperature (MT), and high temperature (HT). MT and HT groups reached, respectively, 52.3 ± 5.1 and 63.8 ± 7.5 °C at the end of exposure. Effectiveness of the treatment was assessed by evaluating the bacteria amount of the treated abscess 1 and 4 days after treatment. Myeloperoxidase (MPO) assay evaluating the neutrophil amount was performed to assess the local neutrophil recruitment and the white blood cell count was used to evaluate the systemic inflammatory response after focused ultrasound treatment.

RESULTS

Macroscopic evaluation of treated abscess indicated a diminution of external size of abscess 1 day after treatment. Treatment did not cause open wounds. The median (lower to upper quartile) bacterial count 1 day after treatment was 6.18 × 10(3) (0.76 × 10(3)-11.18 × 10(3)), 2.86 × 10(3) (1.22 × 10(3)-7.07 × 10(3)), and 3.52 × 10(3) (1.18 × 10(3)-6.72 × 10(3)) cfu/100 μl for control, MT and HT groups, respectively; for the 4-day end point, the count was 1.37 × 10(3) (0.67 × 10(3)-2.89 × 10(3)), 1.35 × 10(3) (0.09 × 10(3)-2.96 × 10(3)), and 0.07 × 10(3) (0.03 × 10(3)-0.36 × 10(3)) cfu/100 μl for control, MT and HT, showing a significant reduction (p = 0.002) on the bacterial load four days after focused ultrasound treatment when treating at high temperature (HT). The MPO amount remained unchanged between groups and days, indicating no change on local neutrophil recruitment in the abscess caused by the treatment. The white blood cell count remained unchanged between groups and days indicating that no systemic inflammatory response was caused by the treatment.

CONCLUSIONS

Focused ultrasound induces a therapeutic effect in abscesses induced by MRSA. This effect is observed as a reduction of the number bacteria without significantly altering the amount of MPO at the site of a MRSA-induced abscess. These initial results suggest that focused ultrasound is a viable option for the treatment of localized MRSA-related infections.