Effects of Antibiotics

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 application of various antibiotics such as rifampicin/tetracycline (63), cefatoxime/trimethoprim (64), or bacteriostatic compounds such as Micropur (Roth, Karlsruhe, Germany) (65) used for root pretreatment or added to collection media is another strategy to prevent biodegradation during root exudate collection. However, depending on dosage and plant species, also phytotoxic effects of antibiotics have been reported (Table 3). Antibiotics in the soil environment... 

L. Landi, L. Badalucco, F. Pomare, and P. Nannipieri, Effectiveness of antibiotics to distinguish the contributions of fungi and bacteria to net nitrogen mineralization, nitrification and re.spiration. Soil Biol. Biocheiii. 25 1771 (1993). 

Ding C, He J (2010) Effect of antibiotics in the environment on microbial populations. Appl... 

Samac, D.A., Willert, A.M., McBride, M.J. and Kinkel, L.L. (2003). Effects of antibiotic-producing Streptomyces on nodulation and leaf spot in alfalfa , Applied and Soil... 

Schmitt H, Flaapakangas H, van Beelen P (2005) Effects of antibiotics on soil microorganisms time and nutrients influence pollution-induced community tolerance. Soil Biol Biochem 37 1882-1892... 

With the increasing appearance of antibiotic-resistant infections, the side effects of antibiotics and superinfection as a consequence of the disturbance of the intestinal microflora, the immediate decision to use antibiotics... 

Diarrhea is a well-known complication of antibiotic therapy. Rates of antibiotic-associated diarrhea (AAD) vary from 5 to 25%. Some antibiotics are more likely to cause diarrhea than others, specifically, those that are broad spectrum and those that target anaerobic flora. This paper reviews the effects of antibiotics on the fecal flora as well as host factors which contribute to AAD. Clinical features and treatment of AAD are also described. Prevention of AAD rests on wise antibiotic policies, the use of probiotics and prevention of acquisition in the hospital setting. Data from clinical trials suggest that poorly absorbed antimicrobials might have a decreased risk of causing AAD and Clostridium difficile-associated disease, as concluded from studies of antibiotics used for preoperative bowel decontamination and poorly absorbed antibiotics used for traveler s diarrhea. Controlled trials would prove this but are not yet available. Probiotics may be a good adjunct to poorly absorbed antibiotics to minimize the risk of diarrhea associated with antibiotics. 

The effects of antibiotics on anaerobic and aerobic flora are shown in table 3. These data are from a variety of studies of human volunteers or patients given preoperative antibiotics but receiving various antibiotics by various routes [31-44], Variations in data can be explained by methodological differences between studies as well as... 

Research on the selective effects of antibiotic soaps on bacteria are not yet far advanced, but initial evidence suggests that they are used far too frequently, with the possible risk of producing infections resistant to the best available antibiotics. See Larson, E., A. Aiello, et al. (2003). Short- and long-term effects of handwashing with antimicrobial or plain soap in the community./oumoZ of Community Health 28(2) 139-150. 

The practice of incorporating low levels of antibiotics in livestock feeds to promote growth has been particularly controversial. It is feared that this practice will result in development of resistant bacteria in animals, which will in turn be passed on to humans, thus diminishing the effectiveness of antibiotics in treatment of human disease. A petition from the Natural Resources Defense Council to ban such uses of penicillin and tetracyclines recently was denied by the Secretary of Health and Human Services. The controversy therefore is likely to continue. Opinion on the subject is quite polarized, and several points of view are presented in this book. 

Dingell, J., 1980. "Animal Feeds Effect of Antibiotics" (letter). Science. 208 1069. 

Table II. Effect of Antibiotics on Growth of Germ-Free...

Conclusions Growth increase approximately 20% by excluding contamination, or by feeding antibiotic. No effect of antibiotic in absence of contamination. 

Larsen, G. L. Bakke, J. E. The Effect of Antibiotic Treatment on the Metabolism and Enterohepatic Circulation of Propachlor Metabolites in the Rat, unpublished. 

The effects of antibiotics also suggest an etiological role for bacteria in exacerbations in some patients. A meta-analysis of nine studies showed a small overall beneflt with antibiotic treatment for... 

Gomez J., R. Mendez, and J.M. Lemna (1996). The effect of antibiotics on nitrification processes. Applied Biochemistry and Biotechnology 57/58 869-876. 

Some topical anti-infectives contain corticosteroids in addition to antibiotics. There is no convincing evidence that topical corticosteroids inhibit the antibacterial effect of antibiotics when the two are incorporated in the same preparation. In the treatment of secondarily infected dermatoses, which are usually colonized with streptococci, staphylococci, or both, combination therapy may prove superior to corticosteroid therapy alone. Antibiotic-corticosteroid combinations may be useful in treating diaper dermatitis, otitis externa, and impetiginized eczema. 

Hahn, T. and Schulz, R. (2007) Indirect effects of antibiotics in the aquatic environment a laboratory study on detritivore food selection behavior. Hum. Ecol. Risk Assess., 13 (3), 535-542. 

Another example of concern is the effect of antibiotic therapy on the efficiency of the synthetic and semisynthetic steroids used by more than 50 million women as contraceptive agents. Since 1973, many antibiotics such as ampicillin, amoxycillin, chloramphenicol, and sulfonamides have been shown to cause failures of oral contraceptives due to perturbation of intestinal microflora (56, 57). 

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