Use of Antibiotics

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 nutrient sparing effect of antibiotics may result from reduction or elimination of bacteria competing for consumed and available nutrients. It is also recognized that certain bacteria synthesize vitamins (qv), amino acids (qv), or proteins that may be utilized by the host animal. Support of this mode of action is found in the observed nutritional interactions with subtherapeutic use of antibiotics in animal feeds. Protein concentration and digestibiHty, and amino acid composition of consumed proteins may all influence the magnitude of response to feeding antibiotics. Positive effects appear to be largest... 

The sulfa dmgs are stiH important as antimicrobials, although they have been replaced in many systemic infections by the natural and semisynthetic antibiotics. They are of great value in third world countries where problems of storage and lack of medical personnel make appropriate use of antibiotics difficult. They are especially useful in urinary tract infections, particularly the combination of sulfamethoxazole with trimethoprim. Their effectiveness has been enhanced by co-adniinistration with dihydrofolate reductase inhibitors, and the combination of sulfamethoxazole with trimethoprim is of value in treatment of a number of specific microbial infections. The introduction of this combination (cotrimoxazole) in the late 1960s (1973 in the United States) resulted in increased use of sulfonamides. 

That bacterial resistance predates the era of clinical use of antibiotics by several hundred millions of years is the recent result of genomic sequence data mining from antibiotic-producing microorganisms. These are supposed to be the inventors of antibiotic resistance genes which they had developed to protect themselves from the lethal action of their own antibiotics [4]. 

The use of antibiotics is not recommended, except for the treatment of infectious exacerbations of COPD and other bacterial infections. Influenza vaccines decrease illness and death in COPD patients. Pneumococcal vaccination is also recommended. 

Kunin CM (1967) A guide to use of antibiotics in patients with renal disease. A table of recommended doses and factors governing serum levels. Ann Intern Med 67 (1 ) 151—158... 

A further aspect that may add to the development work relates to the method of administration. In addition to the standards methods of administration associated with human medicines, veterinary medicines may be introduced to animals through medicated feeds. Such practices have been most commonly associated with the use of antibiotics or other substances to enhance animal performance under intensive farming systems. The use of medicated feeds has been phased out in Europe since the end of 2005, with the exception of coccidiostats and histomonostats intended to kill or inhibit protozoa. In the U SA, however, medicated feeds are still commonplace. Thus, the developer may have to consider the stability and appropriate labelling of the drug when compounded into medicated feeds. 

Numerous studies confirmed ubiquity of several antibiotics (i.e., ofloxacin, trimethoprim, roxythromycin, and sulfamethoxazole) in sewage influent, though at low ng level [8, 13, 14]. However, even at very low concentrations they can have significant ecotoxicological effects in the aquatic and terrestrial compartment [15, 16]. Indiscriminate or excessive use of antibiotics has been widely blamed for the appearance of so-called super-bugs that are antibiotic-resistant. It is of crucial importance to control their emissions into the environment through more cautious utilization and monitoring outbreaks of dmg-resistant infections. 

The above addresses only part of the problem. The use of antibiotics is rife in areas such as animal husbandly, agriculture, aquaculture and even in the oil industry to prevent spoilage by contaminating microorganisms. A particularly pertinent example is the use of avoparcin in animal feed for many years. Avoparcin is related to the glycopeptides... 

Wyler AR, Kelly WA. Use of antibiotics with external ventriculostomies. J Neurosurg 1972 37(2) 185-187. 

Prophylactic, continuous use of antibiotics has no effect on the frequency of exacerbations antibiotics should only be used for treating infectious exacerbations. Antitussives are contraindicated because cough has an important protective role. Opioids may be effective for dyspnea in advanced disease but may have serious adverse effects they may be used to manage symptoms in terminal patients. 

Topical antivirals are not used to treat adenovirus conjunctivitis. Topical antibiotics are often prescribed for viral conjunctivitis, ostensibly to prevent bacterial superinfection. In reality, this is a case of the patient insisting on a medication to speed healing.11 Avoid the use of antibiotics for a viral infection.12 Eliminating superfluous antibiotic use also helps prevent the development of antibiotic resistance. 

Risk factors for developing an infection caused by a resistant pathogen generally are related to the prior use of antibiotics, insertion of catheters or other invasive devices, and hospitalization in a unit contaminated/colonized with resistant organisms. The following is a more complete list of factors influencing infection from a resistant organism ... 

Educate patients about upper respiratory tract infections and proper use of antibiotic therapy. 

Use of antibiotics Altered flora of mucosa allowing fungal overgrowth... 

Joseph TN, Chen AL, Di Cesare PE. Use of antibiotic-impregnated cement in total joint arthroplasty. J Am Acad Orthop Surg 2003 11 38 7. 

The use of antibiotics, copper diet supplements and probiotics for growth promotion is prohibited. 

B Foxman, RB Valdez, KN Lohr, GA Goldberg, JP Newhouse, RH Brook. The effect of cost sharing on the use of antibiotics in ambulatory care results from a population based randomized controlled trial. J Chron Dis 40(5) 429-437, 1987. 

Philips I, Casewell M, Cox T, Degroot B, Friis C, Jones R, Nightingale C, Preston R, Waddell J (2004) Does the use of antibiotics in food animals pose a risk to human health A critical review of published data. J Antimicrob Chemother 53 28-52... 

More recently, a range of other quality and safety issues have been recognised by consumers and now influence poultry meat and egg buying patterns and behaviour. Most importantly this includes (i) the routine use of antibiotics as growth promoters and curative medicines and the potential for development of transferable antibiotic resistance, (ii) risk associated with enteric pathogen (e.g. Salmonella and Campylobacter) and toxin (e.g. dioxin) contaminants of poultry products, (iii) the environmental impact of poultry production and (iv) the sensory and nutritional quality of eggs and poultry meat (Menzi et al., 1997 Hamm et al., 2002 Rodenburg et al., 2004 Horsted et al., 2005). 

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