Antibiotics gentamycin

Figure 7.32 The structure of the aminoglycoside antibiotic gentamycin. The drug may be used as a mixture and R and R = H or CH3, depending on the particular component.

One of the first examples is a polymer network that consists of polyvinylalco-hol crosslinked by a thrombin-degradable peptide-linker [108] and the encapsulated antibiotic Gentamycin. In the case of a wound infection, the thrombin content increases dramatically. This enzyme degrades the co-network, and releases the Gentamycin, which then fights a possible bacterial infection (see Fig. 7). Suzuki and Tanihara have shown that the antibiotic is only released in the presence of thrombin and only then effectively kills S. aureus and P. aeruginosa cells [109, 110],... 

Pseudomonas also contaminates agar and grain cultures, inhibiting mycelial growth. The use of antibiotics (gentamycin sulfate) or micron filters prevents outbreaks of this contaminant. A few species cause the mycelium to grow more rapidly and luxuriantly. Similarly, considerable attention has centered on the beneficial role of Pseudomonas putida and allies in the casing layer. This subject is discussed in detail in Appendix II. 

The autoclavable antibiotic gentamycin is derived from a genus closely allied to Streptomyces, the genus Micromonospora. 

Lewis JE, Nelson JC, Elder HA (1972) Radioimmunoassay of an antibiotic gentamycin. Nature New Biol 239 214-216... 

The objective of antibiotic treatments is to reduce the density of microbial pathogen in infected udder tissues and thereby improve the capacity of the animal s immune system to deal with the infection. The effect of a successful antibiotic treatment is therefore self-cure of mastitis (Hamann and Kromker, 1999). However, some antibiotics (e.g. tetracycline and gentamycine) may also have negative side effects on the animal s immune response to udder infection, as they have been shown to inhibit/reduce phagocytosis of the animal s own defence cells (Nickerson et al 1986). 

The steady-state maximum plasma concentration, Cmaxss, of gentamycin and tobramycin are 6 to 10 mcg/mL. The Cmax ss of amikacin is 25 to 30 mcg/mL. The Cmin ss of both gentamycin and tobramycin is 0.5 to 1.5 mcg/mL, while that of amikacin is 5 to 8 mcg/mL. In order for these drugs to be effective, it is important to closely monitor their therapeutic concentrations. An important observation of these antibiotics is that with prolonged therapy, the Cminsl, values increase. This increase is due to the renal impairment. In the case where Cmin ss is less than the desired Cmin ss, the dose may be insufficient. 

Fig. 6.12. Two-step activation of a poly(vinyl alcohol)-linker-gentamycin device for wound-selective delivery of the antibiotic [44]. The overexpressed enzyme thrombin is the activity targeted by the thrombin-sensitive peptide linker.

FSIS laboratories also use chemical techniques and instrumentation to identify select antibiotic residues. The tetracyclines of interest are identified by thin layer chromatography. Sulfonamides are detected and quantified by fluorescence thin lay chromatography and confirmed by gas chromatography/mass spectrometry. Amoxicillin and gentamycin are identified and/or quantified by high pressure liquid chromatography. Similar techniques are used to identify ionophores and other antimicrobials of interest. 

The primary application of RIA for antibiotics has been in the medical area, and primarily for antibiotics not used in agriculture. Assays have been developed for gentamicin tobramycin, sisomicin, netilmicin and for hygromycin B, an antibiotic used primarily in agriculture (36-37, 22-24). Gentamycin could be measured as low as 80 pg, tobramycin 280 pg, netilmicin 300 pg mL. 

Unwin, J. Standage, S. Wellington, E. Gentamycin Antibiotics Patent GB (0303767.8)-A, 18-FEB-2003 Coventry, England The University of Warwick. 

The aminoglycoside antibiotics streptomycin (Box 20-B),c d u v the neomycins,w paromomycin (see drawing below),c x z gentamycin,aa and kanamycin have one structural unit in common. They often bind to 16S ribosomal RNA in the decoding center. 

Scheme 1. Aminoglycoside antibiotics Sisomycin and Gentamycin derivatives the glycoside linkage to 0-6 of the streptamine is rotated clockwise hv 120° com oared...

Antibiotics such as neomycin, streptomycin, kanamycin, gentamycin, polymyxin A, polymyxin B, colistin, lincomycin, and tetracycline have all been implicated as augmenting the action of the nondepolarizing agents. 

The toxicity of aminoglycosides in the kidney and other organs is concentration-dependent. Antibiotics such as kanamycin and gentamycin have their half-lives doubled in elderly patients. The elderly commonly suffer from osteoarthritis and (less commonly) rheumatoid arthritis. NSAIDs must be carefully used in geriatric patients, as they cause GI toxicity. For example, aspirin causes GI irritation... 

Cultivation of cestodes presents a number of problems, many of which are shared with other parasitic helminths, such as trematodes and nematodes (796,800,810). Some problems, however, are unique to cestodes, particularly those related to the tapeworm s lack of an alimentary canal. Since cestodes normally inhabit the intestine of vertebrates, a major stumbling block to culture attempts in the past has been the initial establishment of sterility. Availability of antibiotics such as gentamycin, penicillin and streptomycin has largely eliminated this difficulty, and there now seems no reason why any species from any host habitat cannot be obtained in a sterile condition. 

---