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European Review For Medical and... Apr 2019Diabetic foot ulcers (DFUs), a micro-vascular complication, are associated with a substantial increase in morbidity and mortality. DFUs are a complicated mixture of... (Review)
Review
Diabetic foot ulcers (DFUs), a micro-vascular complication, are associated with a substantial increase in morbidity and mortality. DFUs are a complicated mixture of neuropathy, peripheral arterial diseases, foot deformities, and infections. Foot infections are frequent and potentially devastating complications. Infection prospers in more than half of all foot ulcers and is the factor that most often leads to lower extremity amputation. The complications of microbial flora span the spectrum from superficial cellulitis to chronic osteomyelitis and gangrenous extremity lower limb amputations. Wounds without confirmed soft tissue or bone infections do not require antibiotic therapy. Mild and moderate infections need empiric therapy covering Gram-positive cocci, while severe infections caused by drug-resistant organisms require broad-spectrum anti-microbials targeting aggressive Gram-negative aerobes and obligate anaerobes.
Topics: Anti-Bacterial Agents; Bacteria, Anaerobic; Diabetes Complications; Diabetic Foot; Humans; Osteomyelitis
PubMed: 30977868
DOI: 10.26355/eurrev_201904_17471 -
Journal of Microbiology, Immunology,... Aug 2020Lemierre's syndrome, also known as post-anginal septicemia or necrobacillosis, is characterized by bacteremia, internal jugular vein thrombophlebitis, and metastatic... (Review)
Review
Lemierre's syndrome, also known as post-anginal septicemia or necrobacillosis, is characterized by bacteremia, internal jugular vein thrombophlebitis, and metastatic septic emboli secondary to acute pharyngeal infections. Modern physicians have "forgotten" this disease. The most common causative agent of Lemierre's syndrome is Fusobacterium necrophorum, followed by Fusobacterium nucleatum and anaerobic bacteria such as streptococci, staphylococci, and Klebsiella pneumoniae. The causative focus mostly originated from pharyngitis or tonsillitis, accounting for over 85% of the cases of Lemierre's syndrome. Pneumonia or pleural empyema is the most common metastatic infection in Lemierre's syndrome. Antimicrobial therapy should be prescribed for 3-6 weeks. The treatment regimens include metronidazole and β-lactam antibiotics. In recent years, the antibiotic stewardship program has resulted in decreased antibiotic prescription for upper respiratory tract infections. The incidence of Lemierre's syndrome has increased over the past decade. F. necrophorum is an underestimated cause of acute pharyngitis or tonsillitis. A high index of suspicion is required for the differential diagnosis of acute tonsillopharyngitis with persistent neck pain and septic syndrome.
Topics: Anti-Bacterial Agents; Bacteria; Bacteria, Anaerobic; Communicable Diseases, Emerging; Fusobacterium necrophorum; Humans; Lemierre Syndrome; Pharyngitis; Sepsis
PubMed: 32303484
DOI: 10.1016/j.jmii.2020.03.027 -
Current Opinion in Microbiology Feb 2015Fusobacterium nucleatum is an anaerobic oral commensal and a periodontal pathogen associated with a wide spectrum of human diseases. This article reviews its implication... (Review)
Review
Fusobacterium nucleatum is an anaerobic oral commensal and a periodontal pathogen associated with a wide spectrum of human diseases. This article reviews its implication in adverse pregnancy outcomes (chorioamnionitis, preterm birth, stillbirth, neonatal sepsis, preeclampsia), GI disorders (colorectal cancer, inflammatory bowel disease, appendicitis), cardiovascular disease, rheumatoid arthritis, respiratory tract infections, Lemierre's syndrome and Alzheimer's disease. The virulence mechanisms involved in the diseases are discussed, with emphasis on its colonization, systemic dissemination, and induction of host inflammatory and tumorigenic responses. The FadA adhesin/invasin conserved in F. nucleatum is a key virulence factor and a potential diagnostic marker for F. nucleatum-associated diseases.
Topics: Bacteria, Anaerobic; Cell Transformation, Neoplastic; Female; Fusobacterium Infections; Fusobacterium nucleatum; Humans; Inflammation; Male; Pregnancy; Pregnancy Complications, Infectious; Virulence; Virulence Factors
PubMed: 25576662
DOI: 10.1016/j.mib.2014.11.013 -
Cancer Medicine Sep 2020Bacteria identified in the oral cavity are highly complicated. They include approximately 1000 species with a diverse variety of commensal microbes that play crucial... (Review)
Review
Bacteria identified in the oral cavity are highly complicated. They include approximately 1000 species with a diverse variety of commensal microbes that play crucial roles in the health status of individuals. Epidemiological studies related to molecular pathology have revealed that there is a close relationship between oral microbiota and tumor occurrence. Oral microbiota has attracted considerable attention for its role in in-situ or distant tumor progression. Anaerobic oral bacteria with potential pathogenic abilities, especially Fusobacterium nucleatum and Porphyromonas gingivalis, are well studied and have close relationships with various types of carcinomas. Some aerobic bacteria such as Parvimonas are also linked to tumorigenesis. Moreover, human papillomavirus, oral fungi, and parasites are closely associated with oropharyngeal carcinoma. Microbial dysbiosis, colonization, and translocation of oral microbiota are necessary for implementation of carcinogenic functions. Various underlying mechanisms of oral microbiota-induced carcinogenesis have been reported including excessive inflammatory reaction, immunosuppression of host, promotion of malignant transformation, antiapoptotic activity, and secretion of carcinogens. In this review, we have systemically described the impact of oral microbial abnormalities on carcinogenesis and the future directions in this field for bringing in new ideas for effective prevention of tumors.
Topics: Alphapapillomavirus; Bacteria, Aerobic; Bacteria, Anaerobic; Bacterial Translocation; Cell Transformation, Neoplastic; Disease Progression; Dysbiosis; Firmicutes; Fungi; Fusobacterium nucleatum; Humans; Immune Tolerance; Microbiota; Mouth; Neoplasms; Oropharyngeal Neoplasms; Porphyromonas gingivalis
PubMed: 32638533
DOI: 10.1002/cam4.3206 -
Nature Nov 2021Antibiotics are used to fight pathogens but also target commensal bacteria, disturbing the composition of gut microbiota and causing dysbiosis and disease. Despite this...
Antibiotics are used to fight pathogens but also target commensal bacteria, disturbing the composition of gut microbiota and causing dysbiosis and disease. Despite this well-known collateral damage, the activity spectrum of different antibiotic classes on gut bacteria remains poorly characterized. Here we characterize further 144 antibiotics from a previous screen of more than 1,000 drugs on 38 representative human gut microbiome species. Antibiotic classes exhibited distinct inhibition spectra, including generation dependence for quinolones and phylogeny independence for β-lactams. Macrolides and tetracyclines, both prototypic bacteriostatic protein synthesis inhibitors, inhibited nearly all commensals tested but also killed several species. Killed bacteria were more readily eliminated from in vitro communities than those inhibited. This species-specific killing activity challenges the long-standing distinction between bactericidal and bacteriostatic antibiotic classes and provides a possible explanation for the strong effect of macrolides on animal and human gut microbiomes. To mitigate this collateral damage of macrolides and tetracyclines, we screened for drugs that specifically antagonized the antibiotic activity against abundant Bacteroides species but not against relevant pathogens. Such antidotes selectively protected Bacteroides species from erythromycin treatment in human-stool-derived communities and gnotobiotic mice. These findings illluminate the activity spectra of antibiotics in commensal bacteria and suggest strategies to circumvent their adverse effects on the gut microbiota.
Topics: Animals; Anti-Bacterial Agents; Bacteria; Bacteria, Anaerobic; Bacteroides; Clostridioides difficile; Dicumarol; Erythromycin; Feces; Female; Gastrointestinal Microbiome; Germ-Free Life; Humans; Macrolides; Male; Mice; Microbiota; Symbiosis; Tetracyclines
PubMed: 34646011
DOI: 10.1038/s41586-021-03986-2 -
Applied and Environmental Microbiology Mar 2018Aerobic methanotrophs have long been known to play a critical role in the global carbon cycle, being capable of converting methane to biomass and carbon dioxide.... (Review)
Review
Aerobic methanotrophs have long been known to play a critical role in the global carbon cycle, being capable of converting methane to biomass and carbon dioxide. Interestingly, these microbes exhibit great sensitivity to copper and rare-earth elements, with the expression of key genes involved in the central pathway of methane oxidation controlled by the availability of these metals. That is, these microbes have a "copper switch" that controls the expression of alternative methane monooxygenases and a "rare-earth element switch" that controls the expression of alternative methanol dehydrogenases. Further, it has been recently shown that some methanotrophs can detoxify inorganic mercury and demethylate methylmercury; this finding is remarkable, as the canonical organomercurial lyase does not exist in these methanotrophs, indicating that a novel mechanism is involved in methylmercury demethylation. Here, we review recent findings on methanotrophic interactions with metals, with a particular focus on these metal switches and the mechanisms used by methanotrophs to bind and sequester metals.
Topics: Bacteria, Anaerobic; Metals; Methane
PubMed: 29305514
DOI: 10.1128/AEM.02289-17 -
The Journal of Biological Chemistry Mar 2020An early exposure to lipid biochemistry in the laboratory of Konrad Bloch resulted in a fascination with the biosynthesis, structures, and functions of bacterial lipids....
An early exposure to lipid biochemistry in the laboratory of Konrad Bloch resulted in a fascination with the biosynthesis, structures, and functions of bacterial lipids. The discovery of plasmalogens (1-alk-1'-enyl, 2-acyl phospholipids) in anaerobic Gram-positive bacteria led to studies on the physical chemistry of these lipids and the cellular regulation of membrane lipid polymorphism in bacteria. Later studies in several laboratories showed that the formation of the alk-1-enyl ether bond involves an aerobic process in animal cells and thus is fundamentally different from that in anaerobic organisms. Our work provides evidence for an anaerobic process in which plasmalogens are formed from their corresponding diacyl lipids. Studies on the roles of phospholipases in revealed distinctions between its phospholipases and those previously discovered in other bacteria and showed how the enzymes are uniquely fitted to the intracellular lifestyle of this significant human pathogen.
Topics: Anaerobiosis; Bacteria, Anaerobic; Fatty Acids; Gram-Positive Bacteria; Lipids; Phosphatidylethanolamines; Plasmalogens
PubMed: 32221031
DOI: 10.1074/jbc.X120.013022 -
International Journal of Infectious... Jan 2021For decades, the term "anti-anaerobic" has been commonly used to refer to antibiotics exhibiting activity against anaerobic bacteria, also designated as anaerobes. This... (Review)
Review
For decades, the term "anti-anaerobic" has been commonly used to refer to antibiotics exhibiting activity against anaerobic bacteria, also designated as anaerobes. This term is used in various situations ranging from infections associated with well-identified pathogens like Clostridioides difficile, or Fusobacterium necrophorum in Lemierre's syndrome, that require specific antibiotic treatments to polymicrobial infections generally resulting from the decreased permeability of anatomical barriers (e.g., intestinal translocation and stercoral peritonitis) or infectious secondary localizations (e.g., brain abscess and infectious pleurisy). In these cases, the causal bacteria generally remain unidentified and the antimicrobial treatment is empirical. However, major progress in the knowledge of human bacterial microbiotas in the last 10 years has shown how diverse are the species involved in these communities. Here, we sought to reappraise the concept of anti-anaerobic spectrum in the light of recent advances in the microbiota field. We first highlight that the term anaerobic itself does not represent the tremendous diversity of the bacteria it spans, and then we stress that the antibiotic susceptibility profiles for most anaerobic bacteria remain unaddressed. Furthermore, we provide examples challenging the relevance of the "anti-anaerobic" spectrum from a clinical and ecological perspective.
Topics: Anaerobiosis; Animals; Anti-Bacterial Agents; Bacteria, Anaerobic; Humans; Microbiota; Terminology as Topic
PubMed: 33127500
DOI: 10.1016/j.ijid.2020.10.052 -
Journal of Industrial Microbiology &... Mar 2019Natural product discovery in the microbial world has historically been biased toward aerobes. Recent in silico analysis demonstrates that genomes of anaerobes encode... (Review)
Review
Natural product discovery in the microbial world has historically been biased toward aerobes. Recent in silico analysis demonstrates that genomes of anaerobes encode unexpected biosynthetic potential for natural products, however, chemical data on natural products from the anaerobic world are extremely limited. Here, we review the current body of work on natural products isolated from strictly anaerobic microbes, including recent genome mining efforts to discover polyketides and non-ribosomal peptides from anaerobes. These known natural products of anaerobes have demonstrated interesting molecular scaffolds, biosynthetic logic, and/or biological activities, making anaerobes a promising reservoir for future natural product discovery.
Topics: Bacteria, Anaerobic; Biological Products; Biosynthetic Pathways; Chromans; Multigene Family; Naphthols; Peptides; Phenazines; Polycyclic Aromatic Hydrocarbons; Polyketides; Thioamides
PubMed: 30284140
DOI: 10.1007/s10295-018-2086-5