CLINICAL MATTERS
“Hey Doc, I have a cold. Azithromycin is okay, right?” This has got to be one of the most common questions doctors get asked nowadays. Unfortunately, most upper respiratory tract infections are caused by viruses and antibiotics won’t help. That doesn’t stop many people from just popping leftover antibiotics or self-medicating. Since people get better from their viruses most of the time anyway, they think they got “cured” and do it again.
To add complexity to the question, there are instances when giving azithromycin is perfectly fine such as if there is a secondary bacterial infection, if someone has an atypical infection like Mycoplasma, or when we suspect a bacterial pneumonia. Deciding whether someone needs antibiotics is a complex skill, and usually involves a complete history, physical exam, and in some cases, an x-ray and laboratory tests. There is no “one size fits all” in medicine so it is best to individualize.
One other recurrent but erroneous local practice that I keep seeing in patients with infected wounds is the use of oral antibiotics as a skin wound disinfectant. This usually takes the form of an amoxicillin capsule that they pull open and then they pour out the powdered contents directly onto the wound. Unfortunately, as any doctor will tell you, this doesn’t really work and can actually make the infection worse since the powder can irritate the wound. While I understand the thought process that goes into these home remedies, the science of how antibiotics work is much more complex and it doesn’t help when people take matters into their own hands.
There are hundreds of antibiotics currently on the market. This is a bewildering assortment, considering penicillin only became commercially available in the 1940s.
In fact, there was such a huge shortage of penicillin during World War II that doctors collected the urine of people who were treated with penicillin to recycle the leftover drug that was peed out. Pretty disgusting, but desperate times called for desperate measures. Unfortunately, bacteria eventually developed resistance to penicillin and so scientists had to tweak the molecule so that it could overcome the bacterial resistance. They did this by chemically altering the different parts of penicillin and coming up with aminopenicillins, ureidopenicillins, cephalosporins, carbapenems, and much more.
New antibiotic drug classes were also discovered, including erythromycin which is a macrolide and the parent drug of azithromycin and clarithromycin. Erythromycin, which also used to be called Ilosone, was discovered in the Philippines in the Ilocos region. A Filipino scientist named Dr. Abelardo Aguilar, who was working for Eli Lilly, isolated it from a soil bacterium (Streptomyces erythreus) and it became one of the most used antibiotics in history. Unfortunately, Dr. Aguilar received no further credit or compensation for his work despite his immense contribution.
Despite the proliferation of antibiotics, antimicrobial resistance is increasingly becoming a global threat as organisms develop mechanisms to defeat the newest antibiotics. Antibiotic misuse is threatening to put us right back where we started before the modern antibiotic era. That would be a truly disastrous situation with people dying of common illnesses because our medications no longer work.
The reason why opening an amoxicillin capsule won’t work on an open wound is because antibiotics have different mechanisms, active forms, coverage, and pharmacologic properties. Oral antibiotics are designed to be absorbed in the stomach, and the dosage plus dosing intervals used are meticulously studied and researched for maximum efficacy. Some antibiotics like ertapenem aren’t absorbed in the gut at all and need to be given intravenously. Some antibiotics like gentamicin may work very well against resistant bacteria in the urine, but do not penetrate the brain or the lungs and won’t be of much use in treating infections in those organs. Certain antibiotic doses need to be adjusted when there is kidney or liver disease. Antibiotics for topical use are usually formulated in an ointment to get better skin penetration. The chemical forms may differ, and the dose is optimized for proper absorption.
The medical subspecialty of Infectious Diseases was formed partly because of the bewildering array of antibiotics and other antimicrobials being used to treat infections. While all doctors know how to use antibiotics, the increasing resistance and complexity of infections has given rise to a discipline dedicated to these diseases. Infectious diseases doctors showed their worth during the Covid-19 pandemic and continue to make a difference in the lives of patients every day. Common and mild infections continue to be treated by primary care practitioners and other specialties. However, when infections are severe or complex, infectious diseases specialists are needed to optimize outcomes.
For instance, an infection of the heart known as endocarditis may need up to six weeks of intravenous antibiotics because a shorter course may not be enough to sterilize the heart valves. Not only are some of these antibiotics tricky to give, but the side effects of the medication can also be significant if not anticipated. Certain forms of drug-resistant tuberculosis are very difficult to treat and require more than a year of treatment. People living with HIV can easily develop a drug-resistant virus if the medications are not carefully chosen and monitored. In addition, the preferred treatments for different diseases are always being reevaluated and modified as we learn more things over time.
Twenty years ago, an infected boil in the Philippines would have been treated with cephalexin or cloxacillin. Nowadays, over half of the Staphylococcus aureus is resistant to these two drugs and we use other drug classes. The length of treatment for a lot of infections has also decreased in many cases, either because new data show equivalence to longer courses, or because antibiotics with long elimination times are used. An example of the latter is that a three-day course of azithromycin is equivalent to a seven-to-10-day course of another antibiotic with a shorter half-life. Modern antibiotic courses do have to contend with more resistant bacteria, but advances have also decreased the number of side effects, and in some cases, have made it more convenient to take. Some newer antibiotic formulations are being made that can be given once a week or less. It is part of a physician’s job to keep up with the latest advances in medicine because what was true last year may no longer be true today. Self-medication with antibiotics is never a good idea. Adhere to your doctor’s prescription, no more and no less. Antibiotics have come a long way and we want them to keep protecting us from infections. If you have any questions, ask your doctor.