Benefits of antibiotics

The benefit of antibiotic aerosols or direct endotracheal instillation has not been consistently demonstrated. 

Is treatment with an antibiotic necessary An important problem in the primary health care setting is treatment of mild upper RTI with antibiotics. It is well known that >90% of these upper RTI are caused by viruses and in these cases antibiotics are useless, even harmful. The benefit of antibiotics for exacerbations of chronic bronchitis is controversial. 

Randomized trials and systematic reviews of trials, therefore, provide the most reliable data on the effects of treatment. That is not to say, however, that non-randomized studies cannot sometimes provide reliable evidence on the benefits of intervention. Few people would doubt the validity of the observational data on the benefits of antibiotic treatment in bacterial meningitis or the benefits of treatment with levodopa in Parkinson s disease. Similarly, clinical guidelines have been revised worldwide on the basis of the non-randomized evidence of the substantial reduction in the risk of early recurrent stroke (see Fig. 19.2, p. 245) as a result of the urgent initiation of standard secondary prevention (Rothwell et al. 2007). 

Mild cases, characterised by pinkness or infection of the eardrum, often resolve spontaneously and need only analgesia emd observation. They are normally viral. A bulging, inflamed eardrum indicates bacterial otitis media usually due to Streptococcus pneumoniae, Haemophilus influenzae, Moraxella (Bran-hamella) catarrhalis. Streptococcus pyogenes (Group A) or Staphylococcus aureus. Amoxicillin or co-amoxiclav is satisfactory, but the clinical benefit of antibiotic therapy is very small when tested in controlled trials. Chemotherapy has not removed the need for myringotomy when pain is very severe, and also for later cases, as sterilised pus may not be completely absorbed and may leave adhesions that impair hearing. Chronic infection presents a similar problem to that of chronic sinus infection, above. 

Hendrickson, J.R. North, D.S. Pharmacoeconomic benefit of antibiotic step-down therapy Converting patients from intravenous ceftriaxone to oral cefpodoxime prox-etil. Ann. Pharmacother. 1995, 29, 561-565. 

Sturlese E, Retto G, Pulia A, et al. Benefits of antibiotic prophylaxis in laparoscopic gynaecological surgery. Clin Exp Obstet Gynecol 1999 26 217-218. 

These include the emergence of potentially dangerous antibiotic resistant microorganisms, the possibility of toxic or allergic reactions in sensitive individuals and/or technological problems of starter culture inhibition associated with antibiotic residues in food products. This paper summarizes the risks, as well as some of the benefits, of antibiotics in foods and feeds. 

FRIEND AND SHAHANi Antibiotics in Foods Benefits of Antibiotics in Foods and Feeds... 

Table 1. Benefits of Subtherapeutic Level of Antibiotic in Food-Producing Animals, % Improvement...

Mechanism of Action. The mechanisms by which antibiotic adrninistration at subtherapeutic levels enhance growth rate and efficiency of gain in growing animals have not been clarified. Possible modes of action include disease control, nutrient sparing, and metaboHc effects. There is extensive evidence that the principal benefit from subtherapeutic use of antibiotics results from the control of harmfiil microorganisms. 

The importance of the penicillins as a class of heterocyclic compounds derives primarily from their effectiveness in the treatment of bacterial infections in mammals (especially humans). It has been estimated that, in 1980, the worldwide production of antibiotics was 25 000 tons and, of this, approximately 17 000 tons were penicillins (81MI51103). The Food and Drug Administration has estimated that, in 1979 in the U.S.A., 30.1 x 10 prescriptions of penicillin V and 44.3 x 10 prescriptions of ampicillin/amoxicillin were dispensed. This level of usage indicates that, compared to other methods of dealing with bacterial infection, the cost-benefit properties of penicillin therapy are particularly favorable. Stated differently, penicillin treatment leads to the elimination of the pathogen in a relatively high percentage of cases of bacterial infection at a relatively low cost to the patient in terms of toxic reactions and financial resources. 

Studies have not shown benefit for additional doses of antibiotic and the duration of antimicrobial prophylaxis should not exceed 24 hours. 

The National Surgical Infection Prevention Project and published evidence suggest that the continuation of antimicrobial prophylaxis beyond wound closure is unnecessary.1 Studies have not shown benefit for additional doses of antibiotic and the duration of antimicrobial prophylaxis should not exceed 24 hours. Longer durations of antibiotic prophylaxis are advocated by some guidelines and will be discussed later. 

The use of the aerosol route for delivery of antibiotics for pulmonary infections remains controversial. The majority of pediatric studies have been conducted in children with cystic fibrosis. In these patients distribution of the antibiotic to the desired tissue site is impeded because of the viscosity of the sputum in patients with acute exacerbations of their pulmonary infections [91,92], Long-term studies have demonstrated preventive benefits of aerosolized antibiotics in children with cystic fibrosis who are colonizing Pseudomonas aeruginosa in their lungs but are not acutely ill [93,94], Cyclic administration of tobramycin administered by nebulizer has received FDA approval [95],... 

If both the farms and the dairy are covered by a reliable control system, the everyday monitoring will take place at the optimal CCP at the farm and analysis of milk samples at the dairy will only be needed at low frequency for verification of the system (Principle 6). This will ensure that there are no antibiotic residues in the milk sold by the dairy, with minimal expenses for control. In fact, the most expensive item will be the cost of the unannounced inspections at the farms to monitor the integrity of the system. However, if not all the farms are covered by a sufficiently good control system, the dairy will have to add the extra costs of its own independent system, in order to be able to take responsibility for this quality aspect. So the main benefit of a supply chain-based system is that it provides full control at the lowest cost. The main drawback is that the more entities that are involved, the greater is the risk that one of them will experience a system failure and this can have disastrous consequences for all those other entities that rely on the defaulting entity for their product control. 

As long as the urine is sterile preoperatively, the risk of SSI after urologic procedures is low, and the benefit of prophylactic antibiotics in this setting is controversial. E. coli is the most frequently encountered organism. 

Vaginal hysterectomies are associated with a high rate of postoperative infection when performed without the benefit of prophylactic antibiotics. 

No milk can be considered hormone free as natural hormones are always present. The question that has been under heated debate since approximately 1995 is whether the bovine somatotropin hormone (BST) injected into cows to increase milk production results in harmful levels of hormone in milk. The use of BST, which is based upon an economic return rather than any health benefit to the animal, raises two important questions what are the health risks to the human consumer, primarily children and what are the effects on the animals It is fairly well accepted that the use of BST increases the incidence of mastitis and therefore the potential for increased residues of antibiotic and antimicrobials in milk. Because of this Canada, Australia, Japan, the U.K., and other European Union countries decided that the health impact on animals was unacceptable and that BST was not to be used in their jurisdictions. Their decisions were not based upon any human health concerns, but strictly on concerns for animal health. 

The underlying idea of the mechanism of action of the sulfonamides is quite general in the search for agents effective against pathogens but safe for humans find a clear biochemical difference between the host and its infectious agent and seek ways to exploit that difference to the benefit of the host and the detriment of the infectious agent. This is exactly what happens with the p-lactam antibiotics, to which we now turn. 

Most of the antibiotics commercially available nowadays are derivatives of natural compounds produced by bacteria or fungi. It is widely accepted that in nature these secondary metabolites can act as weapons for microbial cell defence, inhibiting the growth of competitors. However, it seems that antibiotics have, in nature, more sophisticated and complex functions [1-3]. Many environmental bacteria can not only cope with natural antimicrobial substances but also benefit from their presence. For instance, the use of antibiotics by bacteria as biochemical signals, modulators of metabolic activity or even carbon sources has been demonstrated [1, 2, 4]. In other cases, antibiotics can be tolerated because they have structures similar to the natural substrates of bacterial housekeeping enzymes and thus are inactivated, leading to a natural form of resistance [2]. These are just some... 

This book was developed to provide a current perspective on agricultural use of antibiotics. Topics include some major uses of antibiotics, problems associated with their use from a regulatory standpoint, residues in food including methods of detection, risks to human health from use in feeds, trends in use, and overall risks and benefits. The scope, therefore, is much broader than in several other recent symposia that have focused mainly on the controversy regarding the use of antibiotics as feed additives. Many of the topics included in the present volume have not been discussed under one cover before. 

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