Why we always do not get results from antibiotics even when we are sure that there is a bacterial infection?
Antibiotics are nowadays seen as a culprit rather than a saviour of humankind. Indiscriminate use by non-professional people brings antibiotics to this status. Most of the people including professionals are confused to use this class of drugs. Moreover, in the veterinary profession, very few options are available to treat infections. In commercial poultry production, use of preventive medication and biosecurity programs have a great role and proper implementation of these 2 will surely lead to a profitable business. In western countries ban on antibiotics is very strict as they can’t use them in feed for preventive purposes and now in recent legislation is also going to be prohibited for treatment also, so farming operations becomes more and more difficult to carry out. But in India, antibiotic usage in the feed as well as treatment is still continued and seems likely in the future. In such a scenario, proper usage of antibiotic is the need of the hour. I always suspect that when antibiotic given through water along with other chemicals like sanitizers it would probably lower down the effectiveness of antibiotics in a solution due to unwanted chemical interactions.
Usually, 3-4 complications arise with the improper non-professional use of antibiotic
1. Desired results may not be seen when the dose is less or affects growth when given in higher doses like colistin sulfate damage kidneys.
2. When a farmer does not get results with available antibiotic his faith is lost in the brand and when the doctor prescribed it again he overlooks it.
3. Unnecessarily antibiotic resistance arises.
4. Mixing of antibiotics with other drugs, supplements and sanitizers
Proper antibiotic administration and its desired results require deep scientific knowledge of the pathology of the disease, the microbiology of pathogen as well as chemical properties of given antibiotic salt. Pathology and microbiology are comparatively lighter part of above 3 points but drug chemistry (pharmacokinetics) of antibiotic is the quite a complicated part. How drug interacts in a solution individually and how it will behave in a solution with other chemical salts is need to know very precisely to get required results from the antibiotic.
Based on ease of administration and theoretically better bioavailability, the preferred manner to deliver antibacterial drugs in commercial chickens is through the drinking water. Almost 90% of antibiotic administration is done through drinking water. However, in practice, considerable variations in bioavailability among flocks and even among individuals should be expected due to factors such as drinking habits in the flock and of each bird; quality of drinking water, including hard water; environment temperature and, possibly, the presence of sanitizers added to reduce bacterial load in the water.
Many farmers use antibiotics along with sanitizers. The possible interaction of a sanitizer added to the drinking water with a given antibacterial or other supplements or drugs has been questioned by professionals in the field, but almost no documentation of such information is published. No doubt that when 2 or more chemicals are dissolved in a solution they interact or possibly react and obviously after reaction their property usually changes. It is now reasonable to think that the water sanitizer on a farm can influence the stability of the antibiotic in water and consequently its bioavailability may be modified.
For example, iodophors (iodine-polyvinylpyrrolidone) are often utilized to disinfect piping and waterers and to reduce bacterial load in the water. Their efficacy is based on their high reactivity with chemical and organic entities. Thus, chemical its interaction with antibacterial drugs is feasible. Acidifiers are also used as sanitizers but little information is available about their interactions with other chemicals in drinking water. Similarly, chlorine and hypochlorite based water sanitizers are strong oxidizing agents and could most probably oxidize majority of microbes including antioxidant supplement usually give during infections like vitamin E, C, A and even other antibiotics like fluoroquinolones are also liable to be oxidized.
A study conducted recently shows that chlorinated and iodophor sanitizers greatly reduces the activity of enrofloxacin in drinking water. Enrofloxacin with sodium hypochlorite in the drinking water decreased the antimicrobial activity, Cmax, and bioavailability of the drug in a directly proportional manner. Iodine in drinking water reduces Cmax and antimicrobial activity of enrofloxacin in vitro. Further, citrate based acidifier increases Cmax and bioavailability of enrofloxacin which can be explained with the help of the fact that fluoroquinolones are highly soluble in acidic solutions and their antibacterial properties enhance in an acidic environment. Opposite to that absorption of fluoroquinolones by the oral route of administration is drastically decreased by antacid containing magnesium, aluminium and other agents such as sucralfate. Some farmers in the field have a habit of giving sodium bicarbonate along with medicines which influence antibiotic’s working up to some extent.
Likewise, a sulpha group of drugs are highly basic in nature and they usually precipitate in acidic solution due to this fact they are famous for crystal urea. I had first-hand practical experience in my UG days when my colleague was giving ringer lactate to a moribund calf and after sometime, he had to left for another work so to save some time he put Bactrim (sulphamethoxazole) in ringer lactate bottle. That mixture gets precipitated immediately and choked the IV set. Learning by doing has long-lasting impressions over memory, from that day I critically look for drug interaction in solution and I never recommend mixing of drugs until I know their basic chemistry.
Note: Cmax is the maximum (or peak) serum concentration that a drug achieves in a specified compartment or test area of the body after the drug has been administrated and before the administration of a second dose.