Mixed Bacterial Species Research Articles

Streamer formation dynamics with mixed bacterial species: Effects of cultivation conditions, hydrodynamics, and species

Streamer formation dynamics with mixed bacterial species: Effects of cultivation conditions, hydrodynamics, and species

Diagnostic yield of viral multiplex PCR during acute exacerbation of COPD admitted to the intensive care unit: a pilot study

Acute exacerbation of chronic obstructive pulmonary disease (AECOPD) is one of the leading causes of admission to the intensive care unit, often triggered by a respiratory tract infection of bacterial or viral aetiology. Managing antibiotic therapy in this context remains a challenge. Respiratory panel molecular tests allow identifying viral aetiologies of AECOPD. We hypothesized that the systematic use of a respiratory multiplex PCR (mPCR) would help antibiotics saving in severe AECOPD. Our objectives were to describe the spectrum of infectious aetiologies of severe AECOPD, using a diagnostic approach combining conventional diagnostic tests and mPCR, and to measure antibiotics exposure. The study was bicentric, prospective, observational, and included 105 critically ill patients with a severe AECOPD of presumed infectious aetiology, in whom a respiratory mPCR with a viral panel was performed in addition to conventional microbiological tests. Altogether, the microbiological documentation rate was 50%, including bacteria alone (19%), respiratory viruses alone (16%), and mixed viruses and bacterial species (16%). The duration of antibiotic therapy was shorter in patients without documented bacterial infection (5.6 vs. 9 days; P = 0.0006). This pilot study suggests that molecular tests may help for the proper use of anti-infective treatments in critically ill patients with severe AECOPD.

Impact of mixed microalgal and bacterial species on organic micropollutants removal in photobioreactors under natural light

Single microalgae species are effective at the removal of various organic micropollutants (OMPs), however increased species diversity might enhance this removal. Sixteen OMPs were added to 2 continuous photobioreactors, one inoculated with Chlorella sorokiniana and the other with a microalgal-bacterial community, for 112 d under natural light. Three media were sequentially used in 3 Periods: I) synthetic sewage (d 0-28), II) 10x diluted anaerobically digested black water (AnBW) (d 28-94) and III) 5x diluted AnBW (d 94-112). Twelve OMPs were removed>30%, while 4 were<10% removed. Removal efficiencies were similar for 9 OMPs, yet the mixed community showed a 2-3 times higher removal capacity (µg OMP/g dry weight) than C. sorokiniana during Period II pseudo steady state. The removal decreased drastically in Period III due to overgrowth of filamentous green algae. This study shows for the first time how microbial community composition and abundance are key for OMPs removal.

Corrosion behavior of 7B04 aluminum alloy under the synergistic effect of Lacticaseibacillus paracasei and Acinetobacter lwoffi

Corrosion behavior of 7B04 aluminum alloy under the synergistic effect of Lacticaseibacillus paracasei and Acinetobacter lwoffi

Sustainable application of tubular photosynthesis microbial desalination cell for simultaneous desalination of seawater for potable water supply associated with sewage treatment and energy recovery

A sustainable approach for simultaneous desalination of actual seawater for potable water supply, and bioelectrochemical treatment of sewage associated with power generation was evaluated in a tubular photosynthesis desalination microbial fuel cell (PDMC) continually operated for 180days. Anion exchange membrane (AEM) was used to separate the bioanode and desalination compartments, whereby, and cation exchange membrane (CEM) was used to separate the desalination and biocathode compartments. Mixed bacterial species and mixed microalgae were utilized for inoculation of the bioanode and biocathode, respectively. The results revealed that maximum and average desalination efficiencies of saline seawater fed to the desalination compartment were 80±1% and 72±1.2%, respectively. Maximum and average removal efficiencies of the sewage organic content in the anodic compartment were up to 99.3±0.5% and 91.0±0.8%, respectively associated with maximum power output of 430.7±0.7mW/m3. In spite of the heavy growth of the mixed bacterial species and microalgae as well, no fouling of AEM and CEM was observed during the entire period of operation. Kinetic study demonstrated that Blackman model described well the bacterial growth. Dense and healthy growth of biofilm and the microalgae in the anodic and cathodic compartments, respectively were clearly observed during the operation period. The promising outcomes of this investigation demonstrated that the suggested approach is a potential sustainable option for simultaneous desalination of saline seawater for potable water supply, biotreatment of sewage, and power generation.

A comparative study on the performance of microbial fuel cell for the treatment of reactive orange 16 dye using mixed and pure bacterial species and its optimization using response surface methodology

The present work provides an insight on the removal of dye and energy recovery simultaneously by Acinetobacter pitii in microbial fuel cells. It focuses on decolorization of reactive orange 16 dye and electricity production in a microbial fuel cell using bacterial isolate Acinetobacter pitii. This isolate removes 92.70% of color at a fixed concentration of 500 ppm of dye within 24 h on the 20th day of operation. The maximum voltage and current density obtained from the species is found to be 0.4379 V and 0.973 A/m3 at 1000 Ω. The central composite design was used to model the process for the removal of 243 ppm of dye from the initial dye concentration of 295 ppm at pH of 7.5, time 71.27 h, with simultaneous production of 1.06 A/m3 of current density. Analytical techniques such as Chemical Oxygen Demand (COD), Fourier-transform infrared spectroscopy (FTIR), Liquid chromatography and mass spectroscopy analysis (LCMS), Scanning electron microscope (SEM), and carbon-di-oxide (CO2) determination were used to study about the nature of the removal of reactive orange 16 dye in a microbial fuel cell. The toxicity of the degraded sample was assessed using Phytotoxicity analysis.

Bioremediation of real-field slaughterhouse wastewater associated with power generation in algae-photosynthetic microbial fuel cell

Algae-photosynthetic microbial fuel cell (PMFC) could be considered as a promising approach for producing purified water. This study assessed the performance of an algae-PMFC continuously operated for 120 days to treat and demineralize real-field slaughterhouse wastewater associated with bioenergy generation. Mixed bacterial species including Pseudomonas and Bacillus as the dominant species were used to inoculate the anodic chamber, whereby Chlorella vulgaris microalgae were used in the cathodic section. The results showed that maximum removal efficiency of the chemical oxygen demand (COD) and ammonium ions from the actual slaughterhouse wastewater were 99.65% and 70%, respectively. Maximum and average recorded power output were 543.28 and 391.42 mW/m2, respectively. Dense growth of both; the biofilm in the anodic compartment as well as Chlorella vulgaris microalgae in the cathodic compartment were clearly observed after 120-days operation. The promising results of this potential approach encourage the application of PMFC for the treatment of slaughterhouse wastewater.

The extracellular DNA lattice of bacterial biofilms is structurally related to Holliday junction recombination intermediates

Extracellular DNA (eDNA) is a critical component of the extracellular matrix of bacterial biofilms that protects the resident bacteria from environmental hazards, which includes imparting significantly greater resistance to antibiotics and host immune effectors. eDNA is organized into a lattice-like structure, stabilized by the DNABII family of proteins, known to have high affinity and specificity for Holliday junctions (HJs). Accordingly, we demonstrated that the branched eDNA structures present within the biofilms formed by NTHI in the middle ear of the chinchilla in an experimental otitis media model, and in sputum samples recovered from cystic fibrosis patients that contain multiple mixed bacterial species, possess an HJ-like configuration. Next, we showed that the prototypic Escherichia coli HJ-specific DNA-binding protein RuvA could be functionally exchanged for DNABII proteins in the stabilization of biofilms formed by 3 diverse human pathogens, uropathogenic E. coli, nontypeable Haemophilus influenzae, and Staphylococcus epidermidis Importantly, while replacement of DNABII proteins within the NTHI biofilm matrix with RuvA was shown to retain similar mechanical properties when compared to the control NTHI biofilm structure, we also demonstrated that biofilm eDNA matrices stabilized by RuvA could be subsequently undermined upon addition of the HJ resolvase complex, RuvABC, which resulted in significant biofilm disruption. Collectively, our data suggested that nature has recapitulated a functional equivalent of the HJ recombination intermediate to maintain the structural integrity of bacterial biofilms.

Easybiotics: a GUI for 3D physical modelling of multi-species bacterial populations.

3D physical modelling is a powerful computational technique that allows for the simulation of complex systems such as consortia of mixed bacterial species. The complexities in physical modelling reside in the knowledge intensive model building process and the computational expense in calculating their numerical solutions. These models can offer insights into microbiology, both in understanding natural systems and as design tools for developing novel synthetic bacterial systems. Developing a robust synthetic system typically requires multiple iterations around the specify→design→build→test cycle to meet specifications. This process is laborious and expensive for both the computational and laboratory aspects, hence any improvement in any of the workflow steps would be welcomed. We have previously introduced Simbiotics, a powerful and flexible platform for designing and analyzing 3D simulations of mixed species bacterial populations. Simbiotics requires programming experience to use which creates barriers to entry for use of the tool. In the spirit of enabling biologists who may not have programming skills to install and utilize Simbiotics, we present in this application note Easybiotics, a user-friendly graphical user interface for Simbiotics. Users may design, simulate and analyze models from within the graphical user interface, with features such as live graph plotting and parameter sweeps. Easybiotics provides full access to all of Simbiotics simulation features, such as cell growth, motility and gene regulation. Easybiotics and Simbiotics are free to use under the GPL3.0 licence, and can be found at: http://ico2s.org/software/simbiotics.html. We also provide readily downloadable virtual machine sandboxes to facilitate rapid installation.

Enzymatic Study of Linoleic and Alpha-Linolenic Acids Biohydrogenation by Chloramphenicol-Treated Mixed Rumen Bacterial Species.

In the rumen, dietary polyunsaturated fatty acids (PUFA) are reduced by a multistage reaction called biohydrogenation (BH). BH leads to a high proportion of saturated fat in ruminant products, but also products some potential bioactive intermediates like conjugated linoleic and linolenic acids. BH is composed of two kinds of reactions: first an isomerization of PUFA followed by reductions (two for linoleic acid, C18:2n-6; three for α-linolenic acid, C18:3n-3). There is little knowledge about BH enzymes as BH bacterial species are the subject of a lot of studies. Nevertheless, both aspects must be explored to control BH and enhance the fatty acids profile of ruminant products. In the present study, an alternative approach was developed to study the enzymes produced in vivo by mixed ruminal bacteria, using inactivation of bacteria by chloramphenicol, an inhibitor of protein synthesis in prokaryotes, before in vitro incubation. To study C18:2n-6 and C18:3n-3 BH several experiments were used: (1) with different incubation durations (0 to 3) to estimate average rates and efficiencies of all BH reactions, and intermediates production; and (2) with different initial quantities of PUFA (0.25 to 2 mg) to estimate Michaelis–Menten enzymatic parameters, Km and Vmax. A last experiment explored the effect of pH buffer and donor cow diet on C18:2n-6 isomerization pathways. Concerning C18:2n-6 BH, this study confirmed the high saturability of its isomerization, the inhibition of both trans11 and trans10 pathways by a low pH, and the last reduction to stearic acid as the limiting-step. Concerning C18:3n-3, its BH was faster than C18:2n-6, in particular its isomerization (Vmax = 3.4 vs. 0.6 mM/h, respectively), and the limiting-step was the second reduction to t11-C18:1. Besides, our mixed isomerases had a higher affinity for C18:2n-6 than for C18:3n-3 (Km = 2.0 × 10-3 vs. 4.3 × 10-3 M, respectively), but due to their high saturability by C18:2n-6, they had a lower efficiency to isomerize C18:2n-6 than C18:3n-3. Chloramphenicol-treated ruminal fluid would be a meaningful method to study the BH enzymes activities.

Electricity Generation in Microbial Fuel Cell (MFC) by Bacterium Isolated from Rice Paddy Field Soil

Microbial fuel cell (MFC) is an alternative approach in generating renewable energy by utilising bacteria that will oxidize organic or inorganic substrates, producing electrons yielded as electrical energy. Different species of exoelectrogenic bacteria capable of generating significant amount of electricity in MFC has been identified, using various organic compounds for fuel. Soil sample taken from rice paddy field is proven to contain exoelectrogenic bacteria, thus electricity generation using mixed culture originally found in the soil, and pure culture isolated from the soil is studied. This research will isolate the exoelectrogenic bacterial species in the rice paddy field soil responsible for energy generation. Growth of bacteria isolated from the MFC is observed by measuring the optical density (OD), cell density weight (CDW) and viable cell count. Mixed bacterial species found in paddy field soil generates maximum power of 77.62 μW and 0.70 mA of current. In addition, the research also shows that the pure bacterium in rice paddy field soil can produce maximum power and current at 51.32 μW and 0.28 mA respectively.

Aerobic uterine isolates and antimicrobial susceptibility in mares with post-partum metritis.

The potential for life-threatening complications of metritis requires prompt initiation of antimicrobial treatment, often before microbiological test results are reported. However, published studies to guide first-line antibiotic selection are scarce. To report the most frequent bacterial species, antimicrobial susceptibility and prevalence of multidrug resistance (MDR) in cases of equine metritis. Retrospective analysis of uterine bacterial culture and antimicrobial susceptibility test (AST) results from mares with metritis. Data from uterine culture and AST from 45 mares and 88 bacterial isolates were analysed. The frequency of single and mixed infections, bacterial species and susceptibility to antimicrobials was reported. Mixed growth (62.2% mares) was more frequent than pure growth. The most commonly isolated bacterial species was Escherichia coli (30.7%) and mares with mixed growth most commonly grew a combination of Gram-negative and Gram-positive bacteria (65.5%). Gentamicin with penicillin was an appropriate choice for 65.1% of the mares. Trimethoprim/sulfonamide was effective in only 48.8% of the mares. Effective antimicrobial therapy was provided by the combination of penicillin with amikacin (90.7%) or with enrofloxacin (81.4%). Some organisms were also sensitive to tetracyclines, cephalosporins and chloramphenicol. MDR was more frequent in Gram-negative (85.4%) than Gram-positive bacteria (23.5%). Low number of bacteria, limited number of veterinary specific interpretive criteria for equine metritis. Mixed infections were common in equine metritis. Gram-negative bacteria and enterococci were often associated with resistance to the most frequently used antimicrobials. Potentiated sulfonamides are not an appropriate first choice for mares with metritis. While the combination of penicillin and gentamicin may be an appropriate first-line treatment for some mares, use of amikacin or enrofloxacin instead of gentamicin may be preferential.

An evaluation of multiple annealing and looping based genome amplification using a synthetic bacterial community

The low biomass in environmental samples is a major challenge for microbial metagenomic studies. The amplification of a genomic DNA was frequently applied to meeting the minimum requirement of the DNA for a high-throughput next-generation-sequencing technology. Using a synthetic bacterial community, the amplification efficiency of the Multiple Annealing and Looping Based Amplification Cycles (MALBAC) kit that is originally developed to amplify the single-cell genomic DNA of mammalian organisms is examined. The DNA template of 10 pg in each reaction of the MALBAC amplification may generate enough DNA for Illumina sequencing. Using 10 pg and 100 pg templates for each reaction set, the MALBAC kit shows a stable and homogeneous amplification as indicated by the highly consistent coverage of the reads from the two amplified samples on the contigs assembled by the original unamplified sample. Although GenomePlex whole genome amplification kit allows one to generate enough DNA using 100 pg of template in each reaction, the minority of the mixed bacterial species is not linearly amplified. For both of the kits, the GC-rich regions of the genomic DNA are not efficiently amplified as suggested by the low coverage of the contigs with the high GC content. The high efficiency of the MALBAC kit is supported for the amplification of environmental microbial DNA samples, and the concerns on its application are also raised to bacterial species with the high GC content.

In vitro and ex vivo microbial leakage assessment in endodontics: A literature review

The aim of this study was to perform a literature review of published in-vitro and ex-vivo studies, which evaluated microbial leakage in endodontics in the past 10 years. A comprehensive electronic literature search was carried out in PubMed database for English articles published from 2005 to 2016 using the keywords “endodontics,” “in vitro,” “ex vivo,” “microbial leakage,” “microbial penetration,” “saliva,” “Enterococcus faecalis,” “E. faecalis,” “endodontic sealers,” “temporary filling material,” “apical plug,” “mineral trioxide aggregate,” and “MTA.” The keywords were combined using Boolean operators AND/OR. Based on our search strategy, 33 relevant articles were included in the study. There are three main methods for assessment of bacterial microleakage, namely, (A) the dual-chamber leakage model, (B) detection of bacteria using a scanning electron microscope (SEM), and (C) polymerase chain reaction. All bacterial leakage models have some limitations and may yield different results compared to other microleakage evaluation techniques (i.e., dye penetration, fluid filtration, or electrochemical tests). The results of SEM correlated with those of microbial leakage test in most studies. Microbial leakage test using saliva better simulates the clinical setting for assessment of the leakage of single or mixed bacterial species.

Culture independent bacterial identification in post-mortem samples

Investigation of post-mortem samples for a bacterial aetiology is challenging. There may be pathological signs of inflammation and infection, but not always. Further complications arise via detection of organisms derived from agonal or post-mortem translocation from the colonised mucous membranes and contamination artificially introduced by collection processes. Attributing a terminal outcome to the finding of specific bacteria ranges from high certainty for pathogens not associated with the human microbiome, to low certainty when observing mixed bacterial species including normal flora. Clinical features of infection, known individual risk factors, particular bacterial virulence genes, and case histories are important pieces of the puzzle. Treatment with antimicrobials, peculiar nutritional and atmospheric requirements of bacteria, and delays in sample collection can all reduce the ability of traditional culture methods to recover causative organisms. In those circumstances recovery and specific identification of bacterial DNA has been an effective diagnostic augmentation for post-mortem bacteriology. Use of DNA encoding the bacterial ribosomes has been the primary culture independent approach. This technique will be discussed and local cases will be presented. The diagnostic value of 2 nd and 3 rd generation DNA sequencing instrument output and resultant bioinformatically reconstructed microbial genome content from clinical samples will be discussed.

Testing of Cadexomer Iodine against a Variety of Micro-organisms Grown in Single and Mixed Species Biofilms

BACKGROUND/OBJECTIVES: The simplistic definition of a biofilm is a structured community of bacterial cells enclosed in a selfproduced polysaccharidematrix, which adheres to an inert or living surface. Several authors have stated that nearly 2/3 of chronic wounds contain bioburden in the form of biofilms. It has been reported that biofilm-associated infections exceeds $1 billion/year in the US. The purpose of this study was to evaluate the ability of cadexomer iodine dressings to prevent biofilm formation in vitro over a 48 h period using single and mixed species biofilm models. METHODS: Biofilms were grown in a 96-well microtitre plate. The lid was sealed with parafilm and incubated at 37 C for 48 hours. For each dressing tested, replicates were aseptically placed into appropriate wells of a fresh 96-well microtitre plate. Following two wash steps to remove excess stain and subsequent elution of the remaining stain in ethanol, the optical density (OD) at 570 nmwas then measured for each well. The results were grouped into strong biofilm, moderate biofilm, weak biofilm or no biofilm categories. The mixed bacterial species used are common to DUs and PUs. RESULTS: The results indicate that in contrast to a filter paper control (upon which biofilms grew freely) cadexomer iodine prevented biofilm formation against P. aeruginosa, S. aureus and mix species biofilms. CONCLUSIONS: The data suggests that rapid intervention with cadexomer iodine may be useful in preventing biofilm formation in wounds. It is hoped that studies of this typewill allow for enhanced clinician education, patient safety and prove beneficial to facilities with respect to wound care.

Microbiological diagnosis of bacterial endophthalmitis

AbstractPurpose The systematic microbiological documentation of endophthalmitis allows the confirmation of the infectious nature of the disease and the possible adaptation of treatment at the individual level and, at the collective level, the epidemiological characterization of the bacterial spectrum of endophthalmitis.Methods different microbiological techniques will be presented: conventional techniques (media), eubacterial PCR, real time PCRResults It is preferable to inoculate intraocular samples into culture media (a paediatric blood culture bottle or in Brain Heart Infusion (BHI) broth) under sterile conditions in the operating room and to transfer the sample intended for PCR into a sterile tube without residual DNA (DNA‐free) and with a screw cap. Bacterial identifications and antibiograms are then obtained using phenotypic methods. Real time PCR is more sensitive than culture, allows the detection and identification of specific micro‐organisms, DNA quantification, and has a faster turn around time (no post‐PCR step). The PCR amplification of 16S rDNA uses consensus primers (panbacterial PCR) and is followed by identification from analysis of 16S rDNA sequence. This technique has the advantages of amplification of DNA from all bacteria, and identification of bacteria difficult to identify phenotypically (e.g. coagulase‐negative Staphylococcus species). However drawbacks are the possible contaminations, the duration (2‐3 days including sequencing), and the impossibility of differentiating mixed bacterial species in the same clinical sample.Conclusion PCR techniques are complementary tools to culture. New techniques of PCR are needed in order to be faster and more sensitive. Genomic characterization of strain virulence of bacteria involved in endophthalmitis will be further studied.

PCR in acute bacterial endophthalmitis

AbstractPurpose this review aims to summarize studies which assessed the use of PCR in post operative endophthalmitis. Endophthalmitis is a rare but devastating complication of ocular surgeries. There is a need for more rapid and more sensitive microbiological techniques since clinicians should rapidly identify bacterial pathogens.Methods different microbiological techniques will be presented, eubacterial PCR, real time PCRResults Column‐based nucleic acid purification allows removal of DNA‐polymerase inhibitors. Real time PCR is more sensitive than culture, allows the detection and identification of specific micro‐organisms, DNA quantification, and has a faster turn around time (no post‐PCR step). The PCR amplification of 16S rDNA uses consensus primers (panbacterial PCR) and is followed by identification from analysis of 16S rDNA sequence (BIBI). This technique has the advantages of amplification of DNA from all bacteria, and identification of bacteria difficult to identify phenotypically (e.g. coagulase‐negative Staphylococcus species). However drawbacks are the possible contaminations, the duration (2‐3 days including sequencing), and the impossibility of differentiating mixed bacterial species in the same clinical sample. A summary of the main published clinicomicrobiological studies will be presented.Conclusion PCR techniques are complementary tools to culture. New techniques of PCR are needed in order to be faster and more sensitive. Genomic characterization of strain virulence of bacteria involved in endophthalmitis could help clinicians to identify patients needing a more aggressive treatment and to develop new drugs.

Procalcitonin levels in surgical patients at risk of candidemia

Although the majority of cases of sepsis in intensive care unit (ICU) patients are due to bacterial infection, fungal infections are common and their early identification is important so that appropriate treatment can be started. Biomarkers have been used to aid diagnosis of bacterial infections, but their role in fungal infections is less defined. In this study we assessed the value of procalcitonin (PCT) levels for the diagnosis of candidemia or bacteremia in septic patients. We prospectively recorded PCT levels in 48 critically ill surgical patients with signs of sepsis and at high risk for fungal infection, and compared levels in patients with candidemia and bacteremia. Bacterial species were isolated from blood cultures in 16 patients, Candida species in 17, and mixed bacterial and Candida species in 2 patients. PCT levels were less elevated in patients with candidemia (median 0.71 [IQR 0.5-1.1]) than in those with bacteremia (12.9 [2.6-81.2]). A PCT value less than 2 ng/ml enabled bacteremia to be ruled out with a negative predictive value of 94%, and had a similar positive predictive value for candidemia. Our data indicate that a low PCT value in a critically ill septic patient is more likely to be related to candidemia than to bacteremia.

Editorial: Mouse models to study sepsis syndrome in humans

The pathophysiology of sepsis in humans is poorly understood. This common syndrome, responsible for killing hundreds of thousands of patients each year in the United States alone [1], was defined by a consensus statement in 1992 to consist of certain criteria that provide evidence for inflammation in the setting of infection [2]. Severe sepsis was defined as organ failure in the setting of sepsis, and septic shock was defined as severe sepsis where the organ failure was hypotension. The definition for severe sepsis has become the basis for the entry criteria for most clinical trials of sepsis, lumping together heterogenous patients who have some type of infection, some type of secondary inflammation, and some kind of organ failure. The inherent concept in these definitions is that inappropriate or over-abundant inflammation is central to the pathophysiology of the syndrome. At the time that these definitions were made, there were limited numbers of proinflammatory cytokines described (notably, IL-1 and TNF). The dominant hypothesis was that the pathophysiology of sepsis syndrome was related or caused by microbial wall components (such as bacterial LPS), activating immune cells to produce these cytokines, which then in turn induced uncontrolled inflammation. Treatment attempts at blocking these two proinflammatory cytokines failed in patients with sepsis syndrome. Ironically, we now know that deficiency of these cytokines leads to immunocompromise and infections that cause sepsis. Proof of the hypothesis that microbial-induced inflammation is causative in sepsis syndrome is still lacking; this proof will need to come from a study in humans in which part of this cascade is blocked, and there is clear and reproducible, therapeutic benefit. In the meanwhile, numerous experiments worldwide are performed in mouse models with the hope of better understanding microbial-induced inflammation so that such new therapies can be developed. For decades, mouse models to study sepsis have fallen into one of two broad categories: intoxication and infection. In intoxication models, mice are challenged with a noninfectious, proinflammatory compound, such as LPS or killed bacteria. In infection models, the mice are challenged with live bacteria. Multiple variations of these models have been tried over the years with differing endpoints and routes of administration. One of the most-used models, the CLP model, was developed to try to better mimic sepsis in patients in which there is a mixed bacterial species in a relevant tissue compartment. In this model, the cecum of rodents is ligated and punctured with a needle, resulting in spillage of the intestinal contents into the peritoneum and the development of secondary bacterial peritonitis [3]. Unfortunately, all of the mouse models have one substantial and over-riding disadvantage: The disease that mice develop in response to microbial challenge seems to differ from what is seen clinically in humans. Compared with what is seen in sepsis syndrome in humans, mice challenged with high numbers of bacteria, such as in the CLP model, tend to have a shorter duration of disease, which is often terminated with a quite sudden death and less organ failure. Secondary derangements in kidney, lung, and liver function that are such an important part of sepsis syndrome and that often lead to death in humans are therefore not easily studied in these mouse models. Rodents are highly resistant to most types of induced inflammation compared with humans. The challenge dose of LPS used in most published in vivo studies in mice is 1–25 mg/kg, which approximates the dose that causes death in half of the mice [4 –7]. This dose is 1000 –10,000 times the dose required to induce severe disease with shock in humans [8, 9] and 1,000,000 times the dose used in carefully controlled study environments in which human volunteers are challenged with highly characterized preparations of 2– 4 ng/kg LPS to elicit fever and cytokines [10]. A direct comparison between the species for live bacteria is obviously not possible. However, in most mouse models, it is necessary to administer high doses of live bacteria to induce illness (usu-