Topical and Systemic Antibiotics

The Mildew Covenant

The discovery of antibiotics is often attributed to Fleming; however, this “discovery” is in the same vein as Columbus and his discovery of the Americas. Substances with antibiotic properties have been used since antiquity to treat infection by practitioners of traditional Chinese medicine. Tetracycline, an antibiotic still in use today, has been detected in the remains of ancient Nubians, Romans, and Egyptians. Fleming’s identification of penicillin doesn’t even represent western medicines discovery of antibiotics. An effective syphilis drug called Compound 606 had been use for more than two decades prior. It’s name was derived from being the sixth substance in the sixth group of compounds being methodically screened in the lab of German microbiologist Paul Ehrlich. The narrative of Alexander Fleming and his serendipitous plates of mold is vestigial World War II propaganda. The story goes that Fleming himself used penicillin to save Winston Churchill after he fell deathly ill in Tunisia. The actual drug used to treat Churchill was a German Sulfa compound but the Fleming story as told served to raise morale. Penicillin was a panacea seeded by God himself into a petri dish of his chosen people. Fleming as the discoverer of antibiotics isn’t a literal truth but rather a parable to remind grade school children that all great things come from Britain.

Antibiotics are substances able to either kill or inhibit the growth of bacteria. Their use revolutionized medicine and has saved countless lives but misuse can be harmful. Overuse and improper duration of treatment has lead to the emergence of multi drug resistant organisms. For example, strains of tuberculosis have been identified in India, Iran, and Italy which are immune to all known antibiotics. Some antibiotics have the potential to cause terrible side effects such as hearing loss or liver failure. Antibiotics are also the most prevalent of allergens with more than one in ten being allergic to penicillin. Because of these risk, antibiotics are only sold under the order of a physician in the United States. This work is neither comprehensive nor being written by a physician. I’m sharing what I’ve learned about the use of antibiotics related to surgical procedures but I am in no way condoning or advising anyone to take them unless they’ve spoken with their medical doctor.

Antibiotics are used in two different forms for a procedure such as an implant: Orally or Topically. Furthermore, the intent of administration can be to either treat an infection or as prophylaxis to prevent one from occurring.

Oral Antibiotics

 Oral Antibiotics for prophylaxis are those administered prior to a surgical procedure in order to prevent infection as a complication. The antibiotic selected is generally a well tolerated broad spectrum. The specific agent chosen is based on the type of infection most likely to occur after a particular surgery. For example, Fluoroquinolone is eliminated from the body intact via urine. For this reason, it’s the antibiotic of choice before procedures on the urinary tract. Those receiving pancreas and kidney transplants are at increased risk of fungal infection and thus one of the first line prophylactic antibiotics is the anti-fungal agent fluconazole. The most common prophylactic antibiotic is Cefazolin. It’s a first generation cephalosporin that binds to bacterial cell walls and is active against a wide range of bacteria. There are a number of disadvantages however which makes Cefazolin undesirable for a simple procedure. Cefazolin is not available in an oral form. It must be administered either intravenously or by intramuscular injection. There is also a 10 to 20% risk of allergic cross sensitivity for those with an allergy to penicillin. Finally, Cefazolin isn’t commonly used to treat ill fish. The relevancy of this will be explained later.

The American Society of Health System Pharmacist Clinical Practice Guidelines lists Clindamycin as the second choice prophylactic antibiotic for those with a sensitivity to penicillin. Clindamycin functions by interrupting bacterial protein synthesis. Like any antibiotic it may cause adverse effects. This most often takes the form of nausea and vomiting. More severe effects include C. Dificile infections and colitis although this is somewhat rare. Serious acute reactions such as anaphylaxis occur in less than 0.1% of people making clindamycin a better choice for those fool hardy enough to take an antibiotic without being prescribed by a physician. Clindamycin is also available in an oral form and is a drug commonly used to treat fish.

The reason fish keeps being mentioned is because antibiotics are unavailable for human consumption without a prescription but can be easily purchased at most pet stores catering to fish aficionados. A common brand name is “Fish Cin” which comes in 150mg capsules. One might ask, “Is this safe to take a pet antibiotic?” The capsules being sold for use in aquariums have identical colors and identifying imprints to those sold for humans. While I can’t provide you with a source, all evidence seems to indicate that these capsules are coming from the same manufacturer.

Proper dosing for preprocedural Clindamycin is 900mg by mouth one hour prior to incision. A repeat dose of 900mg by mouth is to be given 6 hours after this time. The use of a prophylactic antibiotic significantly lowers the risk of infection following a procedure.

The other use of antibiotics is to treat an infection that occurs following a procedure. Choosing an antibiotic for this purpose is more difficult in that the wound should be assessed to determine the type and severity of infection. Most often a first generation cephalosporin is used such as Cephalexin. Cephalexin unfortunately does present risk of anaphylaxis and there is a cross-sensitivity for those with a penicillin allergy. If a person has previously taken penicillin or related drugs without effect, Cephalexin can be purchased as a fish antibiotics under the name “Fish Flex.”  The indicated dosing for treatment of a skin infection is 250mg to 500mg every 6 hours for 7 to 21 days. Once again, I’m certainly not advising taking medications without a prescription. If one were to do this however, and an infection hadn’t significantly improved within 7 days it would be wise to see a physician. Some infections aren’t treated by Cephalexin and taking the wrong antibiotic can actually make an infection worse.

Topical Antibiotics

Topical antibiotics are not routinely used as prophylaxis on sutured wounds. Although ample clinical studies have been performed demonstrating that topical antibiotics can decrease infection rates in simple wounds, these substances are known allergen and can result in contact dermatitis with slowed healing and increased scarring. The three most commonly used topical antibiotics are bacitracin, neomycin, and polymyxin b which are often sold together as triple antibiotic ointment. Bacitracin is a broad spectrum topical able to target the majority of bacteria which cause skin infections. A reaction to bacitracin may not only slow healing, it can contribute to increased scarring. Bacitracin was the 2003 allergen of the year in the journal “The Dermatologist” with 8.3% of people tested showing a definite reaction.  Neomycin is a topical antibiotic that has strong activity against gram negative bacteria and partial activity against gram positive. For a person who is not allergic, neomycin can reduce the rate of infection, speed healing, and minimize scarring. For those who are allergic, the contact dermatitis will slow healing and increase scarring. Neomycin was the 2010 allergen of the year with 8.7% of people tested showing a reaction. Polymyxin B works almost exclusively on gram negative bacteria. Although ineffective against gram positive bacteria it has an interesting capability to bind endotoxins. Polymyxin B is also a known causative agent for dermatitis and in those susceptible it slows healing and increases scarring.

Mupirocin is a less commonly used topical antibiotic with excellent gram positive activity. It’s effective against a number of resistant bacteria such as MRSA. Mupirocin is the least likely of the topical agents discussed to cause dermatitis; however, the spectrum of activity is relatively narrow. It’s ineffective against fungi, anaerobic bacteria, mycobacteria, mycoplasma, and chlamydia. Anaerobic bacteria are commonly the cause of skin infections and thus mupirocin alone is ineffective as a prophylactic agent.

These topical antibiotics are most often in a petrolatum base. Interestingly, Petrolatum-based ointments when applied 3 times daily for 1 month after surgery reduce erythema in postsurgical scars. Silicone gels have been shown to be similarly effective and it’s reasoned that these agents work by maintaining moisture. Topical antibiotics are not advised for incisions which are clean and free of infection. If a procedure is performed using sterile technique and proper aftercare is observed they simply aren’t needed and are more likely to cause a problem then prevent one. There are topical creams which can be useful to minimize scarring. These will be discussed further on the aftercare pages.