Listeria monocytogenes is a Gram-positive pathogenic bacterium which can be found in soil or water. Infection with the organism can develop after ingestion of contaminated food products. Small and ...large outbreaks of listeriosis have been described. Listeria monocytogenes can cause a number of clinical syndromes, most frequently sepsis, meningitis, and rhombencephalitis, particularly in immunocompromised hosts. The latter syndrome mimics the veterinary infection in ruminants called "circling disease". Neonatal infection can occur as a result of maternal chorioamnionitis ("early onset" sepsis) or through passage through a birth canal colonized with Listeria from the gastrointestinal tract. ("late onset" meningitis). Treatment of listeriosis is usually with a combination of ampicillin and an aminoglycoside but other regimens have been used. The mortality rate is high, reflecting the combination of an immunocompromised host and an often delayed diagnosis.
Streptococcus pneumoniae (the pneumoccus) is the leading cause of otitis media, community-acquired pneumonia, and bacterial meningitis. The success of the pneumococcus stems from its ability to ...persist in the population as a commensal and avoid killing by immune system. This chapter first reviews the molecular mechanisms that allow the pneumococcus to colonize and spread from one anatomical site to the next. Then, it discusses the mechanisms of inflammation and cytotoxicity during emerging and classical pneumococcal infections.
Acute infections caused by pathogenic bacteria have been studied extensively for well over 100 years. These infections killed millions of people in previous centuries, but they have been combated ...effectively by the development of modern vaccines, antibiotics and infection control measures. Most research into bacterial pathogenesis has focused on acute infections, but these diseases have now been supplemented by a new category of chronic infections caused by bacteria growing in slime‐enclosed aggregates known as biofilms. Biofilm infections, such as pneumonia in cystic fibrosis patients, chronic wounds, chronic otitis media and implant‐ and catheter‐associated infections, affect millions of people in the developed world each year and many deaths occur as a consequence. In general, bacteria have two life forms during growth and proliferation. In one form, the bacteria exist as single, independent cells (planktonic) whereas in the other form, bacteria are organized into sessile aggregates. The latter form is commonly referred to as the biofilm growth phenotype. Acute infections are assumed to involve planktonic bacteria, which are generally treatable with antibiotics, although successful treatment depends on accurate and fast diagnosis. However, in cases where the bacteria succeed in forming a biofilm within the human host, the infection often turns out to be untreatable and will develop into a chronic state. The important hallmarks of chronic biofilm‐based infections are extreme resistance to antibiotics and many other conventional antimicrobial agents, and an extreme capacity for evading the host defences. In this thesis, I will assemble the current knowledge on biofilms with an emphasis on chronic infections, guidelines for diagnosis and treatment of these infections, before relating this to my previous research into the area of biofilms. I will present evidence to support a view that the biofilm lifestyle dominates chronic bacterial infections, where bacterial aggregation is the default mode, and that subsequent biofilm development progresses by adaptation to nutritional and environmental conditions. I will make a series of correlations to highlight the most important aspects of biofilms from my perspective, and to determine what can be deduced from the past decades of biofilm research. I will try to bridge in vitro and in vivo research and propose methods for studying biofilms based on this knowledge. I will compare how bacterial biofilms exist in stable ecological habitats and opportunistically in unstable ecological habitats, such as infections. Bacteria have a similar lifestyle (the biofilm) in both habitats, but the fight for survival and supremacy is different. On the basis of this comparison, I will hypothesize how chronic biofilm infections are initiated and how bacteria live together in these infections. Finally, I will discuss different aspects of biofilm infection diagnosis. Hopefully, this survey of current knowledge and my proposed guidelines will provide the basis and inspiration for more research, improved diagnostics, and treatments for well‐known biofilm infections and any that may be identified in the future.
Summary in Danish (dansk resumé)
Akutte infektioner forårsaget af patogene bakterier har været studeret dybtgående i mere end 100 år. Disse infektioner dræbte millioner af mennesker i de forrige århundreder, men kan nu bekæmpes effektivt med udviklingen af de moderne vacciner, antibiotika og forbedret hygiejne. Mens den meste forskning inden for bakteriel patogenese har fokuseret på de akutte infektioner, er betydningen af disse sygdomme nu suppleret med en ny kategori af kroniske infektioner forårsaget af bakterier som vokser i slim‐indkapslede aggregater, også kendt som biofilm. Biofilminfektioner såsom lungebetændelse hos patienter med cystisk fibrose, kroniske sår, kronisk mellemørebetændelse og infektioner på implantater og katetre, påvirker millioner af mennesker i den udviklede verden hvert år, mange med dødsfald til følge. Dybest set, kan bakterier optræde i to livsformer ved vækst og formering. I den ene form, optræder bakterierne som enkelte uafhængige celler (planktoniske), og i den anden form er bakterierne organiseret og fikseret i aggregater. Den sidstnævnte form bliver almindeligvis benævnt som biofilmvækstfænotypen. Akutte infektioner antages at involvere planktoniske bakterier og kan normalt behandles med antibiotika, men en succesfuld behandling afhænger af en præcis og hurtig diagnose. I de tilfælde, hvor det lykkes bakterierne at danne en biofilm inde i et menneske, viser infektionen sig oftest at være uhelbredelig og vil udvikle sig til en kronisk tilstand. De vigtige egenskaber ved kroniske, biofilmbaserede infektioner er en ekstrem resistens over for antibiotika, samt en række andre konventionelle antimikrobielle stoffer og en ekstrem evne til at undgå værtens immunforsvar. I denne afhandling vil jeg samle den aktuelle viden om biofilm med vægt på kroniske infektioner, samt retningslinjer for diagnose og behandling af disse infektioner, og relatere dette til min seneste forskning inden for biofilmområdet. Jeg vil fremlægge beviser til støtte for det synspunkt, at biofilmfænotypen dominerer kroniske bakterielle infektioner, at bakteriernes sammenklumpning er en naturlig egenskab, og at den efterfølgende udvikling af biofilm sker som en tilpasning til de ernæringsmæssige og miljømæssige forhold. Jeg vil lave en række sammenligninger med det formål at fremhæve, ud fra mit synspunkt, de vigtigste aspekter af biofilm og hvad der skal udledes af de sidste årtiers forskning i biofilm. Jeg vil forsøge at bygge bro mellem in vitro‐ og in vivo‐ forskning og foreslå, hvordan man kan studere biofilm med denne viden i tankerne. Jeg vil sammenligne hvordan bakterielle biofilm findes både i økologiske stabile miljøer og opportunistiske økologiske ustabile miljøer, såsom infektioner. Bakterierne deler samme livsstil (biofilm) i begge habitformer, men kampen for overlevelse og for overherredømme er anderledes. Baseret på dette vil jeg også forsøge at forudsige og illustrere, hvordan kroniske biofilminfektioner opstår, og hvordan bakterier lever sammen i infektioner. Endelig vil jeg diskutere forskellige aspekter af diagnosticeringen af biofilminfektioner. Denne gennemgang af viden og de efterfølgende retningslinjer kan forhåbentlig danne grundlag og inspiration for meget mere forskning og for forbedret diagnostik og behandling af de accepterede biofilminfektioner og muligvis også for de infektioner, som vil blive identificeret som biofilminfektioner i fremtiden.
The purpose of this article is to review the spectrum, etiopathogenesis, clinical presentation, imaging features, differential diagnoses, and management of emphysematous infections of the abdomen and ...pelvis.
Emphysematous infections are associated with high morbidity and mortality and thus need urgent medical and surgical interventions. CT is the most sensitive modality to detect gas; CT provides definitive diagnosis in most cases and can depict the extent of involvement.
A prevailing opinion is that the strains of Pseudomonas aeruginosa that infects both plants and humans are two separate species. This study strongly disputes that notion until the modern molecular ...technology proves otherwise. This paper examines a spectrum of strains occurring in nature, their habitats, dissemination, their relationship to clinical strains, and the environmental conditions that favor their colonization of plants. The isolates were obtained from clinical specimens, plants, soil, and water. The identity of these strains was confirmed using pyocin typing and biochemical assays. The data reveal that agricultural soils, potted ornamental plants, hoses, fountains, and faucets frequently harbored P. aeruginosa. However, it was not commonly found in semi-arid areas, suggesting that moisture and high humidity is necessary for colonization and survival. Though found in soil, P. aeruginosa was seldom isolated on edible plant parts. The pathogenicity of various strains on plants was tested by inoculating vegetables, lettuce slices (Lactuca sativa L. "Great Lakes"), celery stalks (Apium graveolens L. var. Dulce, potato tuber slices (Solanum tuberosum L. "Whiterose"), tomato (Lycopersicon esculentum L. Mill), cucumber (Cucumis sativus L.), rutabaga (Brassica campestris L.), and carrot (Daucus carota L. var sativa). There was considerable variation in the strains' ability to cause rot, but no difference was observed between clinical isolates and others from agricultural fields, water, and soil. Two of the clinical isolates from burn patients, P. aeruginosa PA13 and PA14, exhibited the greatest virulence in causing rot in all the plants that were tested, especially on cucumber, lettuce, potato, and tomato. The study discusses how closely the epidemiology of P. aeruginosa relates to many plant pathogens, and the ability of human isolates to colonize plants and food material under favorable conditions. The biochemical and phenotypic similarity among strains from the clinical and agricultural material is strongly indicative that they are the same species and that plants and soil are natural reservoirs for P. aeruginosa.
Listeria monocytogenes (Lm) is a foodborne human pathogen responsible for severe infections, including septicaemia, neurolisteriosis, and maternal–foetal and focal infections. Little is known about ...Lm-associated respiratory tract or lung infections.
We conducted a retrospective study of culture-proven cases of Lm pleural infections and pneumonia reported to the French National Reference Centre for Listeria from January 1993 to August 2016.
Thirty-eight consecutive patients with pleural infection (n = 32), pneumonia (n = 5), or both (n = 1) were studied; 71% of these were men. Median age was 72 (range 29–90). Two patients presented with concomitant neurolisteriosis. All patients but one reported at least one immunosuppressive condition (97%), with a median number of 2 (range 0–5), including 29% (8/28) with current exposure to immunosuppressive therapy and 50% (17/34) with ongoing neoplasia; 75% (21/28) reported previous pleural or pulmonary disease. Antibiotic therapy mostly consisted in amoxicillin (72%) associated with aminoglycoside in 32%. Chest-tube drainage was performed in 7/19 patients with empyema (37%); 25% of the patients (7/30) required intensive care management. In-hospital mortality reached 35% and occurred after a median time interval of 4 days (range 1–33 days). Three patients had recurrence of empyema (time interval of 1 week to 4 months after treatment completion). Altogether, only 13/31 patients (42%) diagnosed with Lm respiratory infection experienced an uneventful outcome at 2-year follow-up.
Lm is a rare but severe cause of pneumonia and pleural infection in older immunocompromised patients, requiring prompt diagnosis and adequate management and follow-up.
Actinomycetes, a Gram positive bacteria, well reported as a source of antibiotics, also possess potential to control various plant pathogens, besides acting as plant growth promoting agent. Chemicals ...in different forms are extensively being used in vegetable farming, adversely affecting the environment and consumer health. Microbial agent like actinomycetes can substantially replace these harmful chemicals, and have now started finding a place as an important input in to farming practices. Only selected vegetable crops belonging to 11 different families have been explored with use of actinomycetes as biocontrol and plant growth promoting agent till now. It provides ample opportunities to vegetable researchers, to further explore with use of this very important group of microorganisms, in order to achieve even higher production level of safe vegetables. Mycostop and Actinovate are two actinomycetes based formulations globally available for use in vegetable farming as a substitute for chemical formulations. Present review article has summarized the literature available on use of actinomycetes in vegetable farming. Existing wide gap in knowledge, and potential thrust areas for future research have also been projected.
The spread of carbapenem-resistant Enterobacteriaceae (CRE) in healthcare settings challenges clinicians worldwide. However, little is known about dissemination of CRE in livestock, food, and ...companion animals and potential transmission to humans.
We performed a systematic review of all studies published in the PubMed database between 1980 and 2017 and included those reporting the occurrence of CRE in samples from food-producing and companion animals, wildlife, and exposed humans. The primary outcome was the occurrence of CRE in samples from these animals; secondary outcomes included the prevalence of CRE, carbapenemase types, CRE genotypes, and antimicrobial susceptibilities.
We identified 68 articles describing CRE among pigs, poultry, cattle, seafood, dogs, cats, horses, pet birds, swallows, wild boars, wild stork, gulls, and black kites in Africa, America, Asia, Australia, and Europe. The following carbapenemases have been detected (predominantly affecting the genera Escherichia and Klebsiella): VIM, KPC, NDM, OXA, and IMP. Two studies found that 33–67% of exposed humans on poultry farms carried carbapenemase-producing CRE closely related to isolates from the farm environment. Twenty-seven studies selectively screened samples for CRE and found a prevalence of <1% among livestock and companion animals in Europe, 2–26% in Africa, and 1–15% in Asia. Wildlife (gulls) in Australia and Europe carried CRE in 16–19%.
The occurrence of CRE in livestock, seafood, wildlife, pets, and directly exposed humans poses a risk for public health. Prospective prevalence studies using molecular and cultural microbiological methods are needed to better define the scope and transmission of CRE.
Over the last 10-15 years, our understanding of the composition and functions of the human gut microbiota has increased exponentially. To a large extent, this has been due to new 'omic' technologies ...that have facilitated large-scale analysis of the genetic and metabolic profile of this microbial community, revealing it to be comparable in influence to a new organ in the body and offering the possibility of a new route for therapeutic intervention. Moreover, it might be more accurate to think of it like an immune system: a collection of cells that work in unison with the host and that can promote health but sometimes initiate disease. This review gives an update on the current knowledge in the area of gut disorders, in particular metabolic syndrome and obesity-related disease, liver disease, IBD and colorectal cancer. The potential of manipulating the gut microbiota in these disorders is assessed, with an examination of the latest and most relevant evidence relating to antibiotics, probiotics, prebiotics, polyphenols and faecal microbiota transplantation.
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