Bacterial persistance

The presence of a foreign body in an infected site markedly rednces the likelihood for snccess-ful antibiotic therapy. Prosthetics such as cardiac valves, artificial joints, pacemakers, vascnlar grafts, and various shunts promote the formation of a bacterial biofilm that impairs phagocytosis within the film, the slower growth of bacteria may also reduce antibiotic activity and favor bacterial persistence. Infections associated with foreign bodies thus are characterized by frequent relapses and failure, even with long-term antibiotic therapy. Successful therapy usually requires removal of the foreign material. 

Legume bacteria are usually sufficiently tolerant of unfavorable soil conditions to be able to persist under most conditions that the host plant can endure. However, the bacteria prefer a neutral medium and hence Uming the soil where needed is often advisable both for the growth of the plant for the persistence of the bacteria in the soil. Experience has shown that good inoculation requires not just one bacterial cell per seed but several, and hence a good soil environment for bacterial persistence and multiplication is important. 

Bryan, L. E., 1989. Leading articles Two forms of antimicrobial resistance bacterial persistence and positive function resistance. Journal of Antimicrobial Chemotherapy 23, 817-823. 

BALABAN NQ, MERRIN J, CHAU R, KOWALIK L and LEiBLER s (2004), Bacterial persistence as a phenotypic switch . Science, 305,1622-1625. 

Many key protein ET processes have become accessible to theoretical analysis recently because of high-resolution x-ray stmctural data. These proteins include the bacterial photosynthetic reaction centre [18], nitrogenase (responsible for nitrogen fixation), and cytochrome c oxidase (the tenninal ET protein in mammals) [19, 20]. Although much is understood about ET in these molecular machines, considerable debate persists about details of the molecular transfonnations. 

The refractory nature of some pollutants, notably, persistent polyhalogenated compounds, has raised problems of bioremediation of contaminated sites (e.g., sediments and dumping sites). There has been interest in the identification, or the production by genetic manipulation, of strains of microorganisms that can metabolically degrade recalcitrant molecules. For example, there are bacterial strains that can reductively dechlorinate PCBs under anaerobic conditions. 

The structural range of industrially important representatives of these groups is enormous, and includes chlorobenzenes (solvents), polychlorinated biphenyls (PCBs) (hydraulic and insulating fluids), and polybrominated biphenyls and diphenyl ethers (flame retardants). There is widespread concern over both the persistence and the potential toxicity of all these compounds, and sites that have become contaminated during their production represent a threat both to the environment and to human health. Pathways for the aerobic bacterial degradation of chlorobenzenes and chlorobiphe-nyls, and their brominated analogs have been discussed in Chapter 9, Part 1. 

Sinusitis, or inflammation of the paranasal sinuses, is better described as rhinosinusitis that also involves inflammation of contiguous nasal mucosa, which occurs in virtually all cases of viral respiratory infections. Acute rhinosinusitis is characterized by symptoms that resolve completely in less than 4 weeks, whereas chronic rhinosinusitis typically persists as cough, rhi-norrhea, or nasal obstruction for more than 90 days. Acute bacterial rhinosinusitis (ABRS) refers to an acute bacterial infection of the sinuses that can occur independently or be superimposed on chronic sinusitis. The focus of this section will be on ABRS and appropriate treatment. 

How long have the patient s symptoms been present If symptoms are mild and present for fewer than 10 days, viral sinusitis is likely. Persistent moderate or acute severe symptoms are more indicative of bacterial infection. 

Peritonitis may be classified as primary, secondary, or tertiary. Primary peritonitis, also called spontaneous bacterial peritonitis, is an infection of the peritoneal cavity without an evident source of bacteria from the abdomen.1,2 In secondary peritonitis, a focal disease process is evident within the abdomen. Secondary peritonitis may involve perforation of the gastrointestinal (GI) tract (possibly because of ulceration, ischemia, or obstruction), postoperative peritonitis, or posttraumatic peritonitis (e.g., blunt or penetrating trauma). Tertiary peritonitis occurs in critically ill patients and is infection that persists or recurs at least 48 hours after apparently adequate management of primary or secondary peritonitis. 

Among pharmaceuticals, antibiotics have become of special concern in recent years. The reason is that these substances are continuously being introduced into the environment and may spread and maintain bacterial resistance in the different compartments. Sulfonamides are very commonly used antimicrobials in humans but mainly in veterinary medicine, due to their broad spectrum of activity and low cost, being the second most widely used veterinary antibiotic in the EU. Their occurrence has been reported in all kinds of water matrices their high excretion rates (after their intake by humans of livestock) and high water solubility make them very ubiquitous and persistent pollutants in the environment. 

Costerton JW, Stewart PS, Greenberg EP. Bacterial biofilms A common cause of persistent infections. Science 1999 284[5418] 1318-1322. 

In a recent study, we found no acquisition of rifaximin resistance in 27 rifaximin-treated subjects colonized by Enterococcus [37]. The MIC50 and MIC90 for the treatment group (rifaximin at a dose of either 400 or 200 mg twice daily for 3 days) were similar (16-64 pg/ml). In two published studies, rifaximin resistance was shown to occur in the bacterial flora of individuals who received treatment with rifaximin at a dose of 800 mg/day for 5 days [9, 27]. Within 1-2 weeks after the end of rifaximin treatment, resistance rates appeared to have decreased to less than 20% of the intestinal flora. The resistant strains detected during treatment appeared to be unstable and unable to persistently colonize the intestinal tract. 

Bump RC, Zuspan FP, Bueschling WJ 3rd, Ayers LW, Stephans TJ The prevalence, six-month persistence, and predictive values of laboratory indicators of bacterial vaginosis (nonspecific vaginitis) in asymptomatic women. Am J Obstet Gynecol 1985,150 917-924. 

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