Contag, C.H. et al. Photonic detection of bacterial pathogens in living hosts. Mol. Microbiol. 18, 593-603

Department of Pediatrics , Stanford University, Palo Alto, California, United States
Molecular Microbiology (Impact Factor: 4.42). 10/1995; 18(4):593 - 603. DOI: 10.1111/j.1365-2958.1995.mmi_18040593.x
Source: PubMed


The study of pathogenic is often limited to ex vivo assays and cell-culture correlates. A greater understanding of infectious diseases would be facilitated by in vivo analyses. Therefore, we have developed a method for detecting bacterial pathogens in a living host and used this method to evaluate disease processes for strains of Salmonella typhimurium that differ in their virulence for mice. Three strains of Salmonella were marked with bioluminescence through transformation with a plasmid conferring constitutive expression of bacterial luciferase. Detection of photons transmitted through tissues of animals infected with bioluminescent Salmonella allowed localization of the bacteria to specific tissues. In this manner progressive infections were distinguished from those that were persistent or abortive. We observed patterns of bio-luminescence that suggested the caecum may play a pivotal role in Salmonella pathogenesis. In vivo efficacy of an antibiotic was monitored using this optical method. This study demonstrates that the real time non-invasive analyses of pathogenic events and pharmacological monitoring can be performed in vivo.

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    • "In BLI, bioluminescent bacteria inoculated into tissue emit a constant signal that can be detected through the tissue of a living animal using an ultrasensitive, cooled charge-coupled device (CCD) camera. Studies show that in vivo BLI is significantly faster and more sensitive than standard techniques for the real-time monitoring of bacterial infections and their treatment [2], [3], [9], [11], [22], [23]. This technology enables quantitative and spatial data to be acquired from defined areas of the animal. "
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    ABSTRACT: Musculoskeletal infections, including surgical-site and implant-associated infections, often cause progressive inflammation and destroy areas of the soft tissue. Treating infections, especially those caused by multi-antibiotic resistant bacteria such as methicillin-resistant Staphylococcus aureus (MRSA) remains a challenge. Although there are a few animal models that enable the quantitative evaluation of infection in soft tissues, these models are not always reproducible or sustainable. Here, we successfully established a real-time, in vivo, quantitative mouse model of soft-tissue infection in the superficial gluteus muscle (SGM) using bioluminescence imaging. A bioluminescent strain of MRSA was inoculated into the SGM of BALB/c adult male mice, followed by sequential measurement of bacterial photon intensity and serological and histological analyses of the mice. The mean photon intensity in the mice peaked immediately after inoculation and remained stable until day 28. The serum levels of interleukin-6, interleukin-1 and C-reactive protein at 12 hours after inoculation were significantly higher than those prior to inoculation, and the C-reactive protein remained significantly elevated until day 21. Histological analyses showed marked neutrophil infiltration and abscesses containing necrotic and fibrous tissues in the SGM. With this SGM mouse model, we successfully visualized and quantified stable bacterial growth over an extended period of time with bioluminescence imaging, which allowed us to monitor the process of infection without euthanizing the experimental animals. This model is applicable to in vivo evaluations of the long-term efficacy of novel antibiotics or antibacterial implants.
    Full-text · Article · Sep 2014 · PLoS ONE
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    • "Bioluminescence imaging (BLI) is today a well-recognized technique for study of the establishment of infectious pathogens in vivo (reviewed in [25], [26]). Using ST transformed with the lux operon from Photorhabdus luminescens, Contag et al. [27] were the first to demonstrate the feasibility of detecting luminescence-generating microbes in a live mouse. BLI is a helpful means to monitor bacterial distribution, to distinguish between weak and strong virulent strains of Salmonella, to differentiate the susceptibility of mouse strains to infection, and to monitor antibiotic therapy. "
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    ABSTRACT: Salmonella enterica serovar Typhimurium (ST) is an enteropathogenic Gram-negative bacterium that causes infection following oral ingestion. ST spreads rapidly along the gastrointestinal tract (GIT) and invades the intestinal epithelium to ultimately reach internal body organs. The probiotic yeast Saccharomyces boulardii BIOCODEX (S.b-B) is prescribed for prophylaxis of diarrheal infectious diseases. We previously showed that S.b-B prevents weight loss in ST-infected mice and significantly decreases bacterial translocation to the spleen and liver. This study was designed to investigate the effect of S.b-B on ST migration along the GIT and the impact of the yeast on the host's early innate immune responses. Bioluminescent imaging (BLI) was used to evaluate the effect of S.b-B on the progression of luminescent Salmonella Typhimurium (ST-lux) in the GIT of mice pretreated with streptomycin. Photonic emission (PE) was measured in GIT extracts (stomach, small intestine, cecum and colon) at various time periods post-infection (PI). PE analysis revealed that, 45 min PI, ST-lux had migrated slightly faster in the mice treated with S.b-B than in the untreated infected animals. At 90 min PI, ST-lux had reached the cecum in both groups of mice. Adhesion of ST to S.b-B was visualized in the intestines of the mice and probably accounts for (1) the faster elimination of ST-lux in the feces, and (2) reduced translocation of ST to the spleen and liver. In the early phase of infection, S.b-B also modifies the host's immune responses by (1) increasing IFN-γ gene expression and decreasing IL-10 gene expression in the small intestine, and (2) elevating both IFN-γ, and IL-10 mRNA levels in the cecum. BLI revealed that S.b-B modifies ST migration and the host immune response along the GIT. Study findings shed new light on the protective mechanisms of S.b-B during the early phase of Salmonella pathogenesis.
    Full-text · Article · Aug 2014 · PLoS ONE
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    • "To this end, bioluminescence can provide a sensitive and innocuous way to detect live or viable microorganisms. Furthermore, in vivo detection of bioluminescent microorganisms is noninvasive, allowing rapid monitoring of the infective state of eukaryotic cells both in culture and in animals (Contag et al. 1995; Francis et al. 2000). The in vivo monitoring of bioluminescence organisms in living animals has been described for bacteria and for fungi (Francis et al. 2000; Doyle et al. 2006; Brock et al. 2008). "
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    ABSTRACT: Photodynamic inactivation of bioluminescent Escherichia coli in the presence of cationic chlorin and isobacteriochlorin photosensitizers (PSs) obtained from 5,10,15,20-tetrakis(pentafluorophenyl)-porphyrin is described. The spectroscopic data for the neutral and cationic derivatives and their photophysical characterizations, especially fluorescence and singlet oxygen generation capacity are also reported. The results show that there is a direct relation between the inactivation efficiency and the increasing number of charges on the molecules. The combined effect of higher wavelength absorption and number of positive charges on the PS shows a 6.1 log reduction during the inactivation process. Overall this study shows that the cationic isobacteriochlorin has high potential to be used as PS for the inactivation of Gram (-) bacteria.
    Full-text · Article · Jan 2014 · Bioorganic & medicinal chemistry letters
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