Browsing by Subject "microbiology"

Now showing 1 - 7 of 7
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    Biodegradable nanofibrous drug delivery systems: effects of metronidazole and ciprofloxacin on periodontopathogens and commensal oral bacteria
    (Springer-Verlag, 2014-12) Bottino, Marco C.; Arthur, Rodrigo A.; Waeiss, R. Aaron; Kamocki, Krzysztof; Gregson, Karen S.; Gregory, Richard L.; Department of Restorative Dentistry, IU School of Dentistry
    OBJECTIVES: The purposes of this study were to fabricate biodegradable polydioxanone (PDS II®) electrospun periodontal drug delivery systems (hereafter referred to as matrices) containing either metronidazole (MET) or ciprofloxacin (CIP) and to investigate the effects of antibiotic incorporation on both periodontopathogens and commensal oral bacteria. MATERIALS AND METHODS: Fibrous matrices were processed from PDS polymer solution by electrospinning. Antibiotic-containing PDS solutions were prepared to obtain four distinct groups: 5 wt.% MET, 25 wt.% MET, 5 wt.% CIP, and 25 wt.% CIP. Pure PDS was used as a control. High-performance liquid chromatography (HPLC) was done to evaluate MET and CIP release. Dual-species biofilms formed by Lactobacillus casei (Lc) and Streptococcus salivarius (Ss) were grown on the surface of all electrospun matrices. After 4 days of biofilm growth, the viability of bacteria on biofilms was assessed. Additionally, antimicrobial properties were evaluated against periodontopathogens Fusobacterium nucleatum (Fn) and Aggregatibacter actinomycetemcomitans (Aa) using agar diffusion assay. RESULTS: A three-dimensional interconnected porous network was observed in the different fabricated matrices. Pure PDS showed the highest fiber diameter mean (1,158 ± 402 nm) followed in a descending order by groups 5 wt.% MET (1,108 ± 383 nm), 25 wt.% MET (944 ± 392 nm), 5 wt.% CIP (871 ± 309 nm), and 25 wt.% CIP (765 ± 288 nm). HPLC demonstrated that groups containing higher amounts (25 wt.%) of incorporated drugs released more over time, while those with lower levels (5 wt.%) the least. No inhibitory effect of the tested antibiotics was detected on biofilm formation by the tested commensal oral bacteria. Meanwhile, CIP-containing matrices inhibited growth of Fn and Aa. CONCLUSION: CIP-containing matrices led to a significant inhibition of periodontopathogens without negatively impairing the growth of periodontal beneficial bacteria. CLINICAL RELEVANCE: Based on the proven in vitro inhibition of periodontitis-related bacteria, future in vivo research using relevant animal models is needed to confirm the effectiveness of these drug delivery systems.
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    Eradication of Pseudomonas aeruginosa biofilms on cultured airway cells by a fosfomycin/tobramycin antibiotic combination
    (Wiley Blackwell (Blackwell Publishing), 2013-02) Anderson, Gregory G.; Kenney, Thomas F.; Macleod, David L.; Henig, Noreen R.; O'Toole, George A.; Department of Biology, School of Science
    Chronic biofilm formation by Pseudomonas aeruginosa in cystic fibrosis (CF) lungs is a major cause of morbidity and mortality for patients with CF. To gain insights into effectiveness of novel anti-infective therapies, the inhibitory effects of fosfomycin, tobramycin, and a 4:1 (wt/wt) fosfomycin/tobramycin combination (FTI) on Pseudomonas aeruginosa biofilms grown on cultured human CF-derived airway cells (CFBE41o-) were investigated. In preformed biofilms treated for 16 h with antibiotics, P. aeruginosa CFU per mL were reduced 4 log10 units by both FTI and tobramycin at 256 mg L(-1) , while fosfomycin alone had no effect. Importantly, the FTI treatment contained five times less tobramycin than the tobramycin-alone treatment. Inhibition of initial biofilm formation was achieved at 64 mg L(-1) FTI and 16 mg L(-1) tobramycin. Fosfomycin (1024 mg L(-1)) did not inhibit biofilm formation. Cytotoxicity was also determined by measuring lactate dehydrogenase (LDH). Intriguingly, sub-inhibitory concentrations of FTI (16 mg L(-1)) and tobramycin (4 mg L(-1)) and high concentrations of fosfomycin (1024 mg L(-1)) prevented bacterially mediated airway cell toxicity without a corresponding reduction in CFU. Overall, it was observed that FTI and tobramycin demonstrated comparable activity on biofilm formation and disruption. Decreased administration of tobramycin upon treatment with FTI might lead to a decrease in negative side effects of aminoglycosides.
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    Incidence of World Health Organization stage 3 and 4 events, tuberculosis and mortality in untreated, HIV-infected children enrolling in care before 1 year of age: an IeDEA (International Epidemiologic Databases To Evaluate AIDS) East Africa regional analysis
    (Ovid Technologies (Wolters Kluwer) - Lippincott Williams & Wilkins, 2014-06) Ciaranello, Andrea; Lu, Zhigang; Ayaya, Samuel; Losina, Elena; Musick, Beverly; Vreeman, Rachel; Freedberg, Kenneth A.; Abrams, Elaine J.; Dillabaugh, Lisa; Doherty, Katie; Ssali, John; Yiannoutsos, Constantin T.; Wools-Kaloustian, Kara; Department of Pediatrics, IU School of Medicine
    BACKGROUND: Few studies have reported CD4%- and age-stratified rates of World Health Organization Stage 3 (WHO3) events, World Health Organization Stage 4 (WHO4) events, tuberculosis (TB) and mortality in HIV-infected infants before initiation of antiretroviral therapy. METHODS: HIV-infected children enrolled before 1 year of age in the International Epidemiologic Databases to Evaluate AIDS East Africa region (October 1, 2002, to November, 2008) were included. We estimated incidence rates of earliest clinical event (WHO3, WHO4 and TB), before antiretroviral therapy initiation per local guidelines, stratified by current age (< or ≥6 months) and current CD4% (<15%, 15-24%, ≥25%). CD4%-stratified mortality rates were estimated separately for children who did not experience a clinical event ("background" mortality) and for children who experienced an event, including "acute" mortality (≤30 days post event) and "later" mortality (>30 days post event). RESULTS: Among 847 children (median enrollment age: 4.8 months; median pre-antiretroviral therapy follow up: 10.8 months; 603 (71%) with ≥1 CD4% recorded), event rates were comparable for those aged <6 and ≥6 months. Current CD4% was associated with risk of WHO4 events for children <6 months of age and with all evaluated events for children ≥6 months old (P < 0.05). "Background" mortality was 3.7-8.4/100 person-years (PY). "Acute" mortality (≤30 days post event) was 33.8/100 PY (after TB) and 41.1/100 PY (after WHO3 or WHO4). "Later" mortality (>30 days post event) ranged by CD4% from 4.7 to 29.1/100 PY. CONCLUSIONS: In treatment-naïve, HIV-infected infants, WHO3, WHO4 and TB events were common before and after 6 months of age and led to substantial increases in mortality. Early infant HIV diagnosis and treatment are critically important, regardless of CD4%.
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    Lipoxin Inhibits Fungal Uptake by Macrophages and Reduces the Severity of Acute Pulmonary Infection Caused by Paracoccidioides brasiliensis
    (Hindawi Publishing Corporation, 2015) Ribeiro, Laura R. R.; Loures, Flávio V.; de Araújo, Eliseu F.; Feriotti, Cláudia; Costa, Tânia A.; Serezani, Carlos Henrique; Jancar, Sonia; Calich, Vera L. G.; Department of Microbiology and Immunology, IU School of Medicine
    Cysteinyl leukotrienes (CysLTs) and lipoxins (LXs) are lipid mediators that control inflammation, with the former inducing and the latter inhibiting this process. Because the role played by these mediators in paracoccidioidomycosis was not investigated, we aimed to characterize the role of CysLT in the pulmonary infection developed by resistant (A/J) and susceptible (B10.A) mice. 48 h after infection, elevated levels of pulmonary LTC4 and LXA4 were produced by both mouse strains, but higher levels were found in the lungs of susceptible mice. Blocking the CysLTs receptor by MTL reduced fungal loads in B10.A, but not in A/J mice. In susceptible mice, MLT treatment led to reduced influx of PMN leukocytes, increased recruitment of monocytes, predominant synthesis of anti-inflammatory cytokines, and augmented expression of 5- and 15-lipoxygenase mRNA, suggesting a prevalent LXA4 activity. In agreement, MTL-treated macrophages showed reduced fungal burdens associated with decreased ingestion of fungal cells. Furthermore, the addition of exogenous LX reduced, and the specific blockade of the LX receptor increased the fungal loads of B10.A macrophages. This study showed for the first time that inhibition of CysLTs signaling results in less severe pulmonary paracoccidioidomycosis that occurs in parallel with elevated LX activity and reduced infection of macrophages.
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    Modeling the interactions of bacteria and Toll-like receptor-mediated inflammation in necrotizing enterocolitis
    (Elsevier, 2013-03-21) Arciero, Julia; Bard Ermentrout, G.; Siggers, Richard; Afrazi, Amin; Hackam, David; Vodovotz, Yoram; Rubin, Jonathan; Department of Mathematical Sciences, School of Science
    Necrotizing enterocolitis (NEC) is a severe disease of the gastrointestinal tract in premature infants, characterized by a disrupted intestinal epithelium and an exaggerated pro-inflammatory response. Since the activation of Toll-like receptor-4 (TLR4) blocks cell migration and proliferation and contributes to an uncontrolled inflammatory response within the intestine, this receptor has been identified as a key contributor to the development of NEC. Toll-like receptor-9 (TLR9) has been shown to sense bacterial genome components (CpG DNA) and to play an anti-inflammatory role in NEC. We present in vitro results demonstrating direct inhibition of TLR4 activation by CpG DNA, and we develop a mathematical model of bacteria-immune interactions within the intestine to investigate how such inhibition of TLR4 signaling might alter inflammation, associated bacterial invasion of tissue, and resulting outcomes. The model predicts that TLR9 can inhibit both the beneficial and detrimental effects of TLR4, and thus a proper balance of action by these two receptors is needed to promote intestinal health. The model results are also used to explore three interventions that could potentially prevent the development of NEC: reducing bacteria in the mucus layer, administering probiotic treatment, and blocking TLR4 activation. While the model shows that these interventions would be successful in most cases, the model is also used to identify situations in which the proposed treatments might be harmful.
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    Sequestration of host metabolism by an intracellular pathogen
    (eLife Sciences Organisation, Ltd., 2016) Gehre, Lena; Gorgette, Olivier; Perrinet, Stéphanie; Prevost, Marie-Christine; Ducatez, Mathieu; Giebel, Amanda M.; Nelson, David E.; Ball, Steven G.; Subtil, Agathe; Department of Microbiology and Immunology, IU School of Medicine
    For intracellular pathogens, residence in a vacuole provides a shelter against cytosolic host defense to the cost of limited access to nutrients. The human pathogen Chlamydia trachomatis grows in a glycogen-rich vacuole. How this large polymer accumulates there is unknown. We reveal that host glycogen stores shift to the vacuole through two pathways: bulk uptake from the cytoplasmic pool, and de novo synthesis. We provide evidence that bacterial glycogen metabolism enzymes are secreted into the vacuole lumen through type 3 secretion. Our data bring strong support to the following scenario: bacteria co-opt the host transporter SLC35D2 to import UDP-glucose into the vacuole, where it serves as substrate for de novo glycogen synthesis, through a remarkable adaptation of the bacterial glycogen synthase. Based on these findings we propose that parasitophorous vacuoles not only offer protection but also provide a microorganism-controlled metabolically active compartment essential for redirecting host resources to the pathogens.
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    Similarities and seasonal variations in bacterial communities from the blood of rodents and from their flea vectors
    (Nature Publishing Group, 2015-07) Cohen, Carmit; Toh, Evelyn; Munro, Daniel; Dong, Qunfeng; Hawlena, Hadas; Department of Microbiology and Immunology, IU School of Medicine
    Vector-borne microbes are subject to the ecological constraints of two distinct microenvironments: that in the arthropod vector and that in the blood of its vertebrate host. Because the structure of bacterial communities in these two microenvironments may substantially affect the abundance of vector-borne microbes, it is important to understand the relationship between bacterial communities in both microenvironments and the determinants that shape them. We used pyrosequencing analyses to compare the structure of bacterial communities in Synosternus cleopatrae fleas and in the blood of their Gerbillus andersoni hosts. We also monitored the interindividual and seasonal variability in these bacterial communities by sampling the same individual wild rodents during the spring and again during the summer. We show that the bacterial communities in each sample type (blood, female flea or male flea) had a similar phylotype composition among host individuals, but exhibited seasonal variability that was not directly associated with host characteristics. The structure of bacterial communities in male fleas and in the blood of their rodent hosts was remarkably similar and was dominated by flea-borne Bartonella and Mycoplasma phylotypes. A lower abundance of flea-borne bacteria and the presence of Wolbachia phylotypes distinguished bacterial communities in female fleas from those in male fleas and in rodent blood. These results suggest that the overall abundance of a certain vector-borne microbe is more likely to be determined by the abundance of endosymbiotic bacteria in the vector, abundance of other vector-borne microbes co-occurring in the vector and in the host blood and by seasonal changes, than by host characteristics.