How Do Antibiotics Work? (continued)
Antibiotics work in a number of different ways, but perhaps it would just be easier to talk about each one individually. I will focus on the pet antibiotics, since these are the ones most of us can stockpile easily. Again trying to make this as simple as I can, I have omitted many technical details. (A cellular biologist may take exception to what I say, saying “He didn’t even discuss peptidoglycan cross linkages by the DD-transpeptidase enzyme!! Who does he think he is!!??” However, I think most of the prepper army will appreciate omission of the technical fluff.)
Penicillin  was the first really effective antibiotic discovered and the starting point from which other antibiotics were developed. The original penicillin worked best if injected, but eventually an oral preparation was developed (called Penicillin VK or phenoxymethylpenicillin potassium), and this is what you get when you buy Fish-Pen.
The penicillin antibiotics are part of the beta-lactam family of antibiotics due to a chemical structure common to these antibiotics called a beta-lactam ring. Other members of the beta-lactam family are the Cephalosporins. Penicillin (and the other beta-lactams) function by deactivating an essential cell wall-building enzyme in the bacteria. With the bacteria unable to repair its cell wall, the cell wall begins to break down and the bacteria literally pops and dies.
Penicillin once treated a wide variety of bacteria, but overuse allowed most bacteria to develop resistance. The most common form of resistance to penicillin is the beta-lactamase enzyme, which cuts the beta-lactam ring, which deactivates the penicillin and renders it harmless to the bacteria. This caused penicillin’s spectrum to become more and more narrow over time as fewer and fewer pathogens responded to it. Today, penicillin is only used as first choice for one infection– strep throat. That’s it. Penicillin’s spectrum is so narrow (because so many things are resistant to it) that we only use it for one thing– killing Streptococcus pyogenes, which is the bacteria that causes strep throat. It can kill a few other bacteria, like Streptococcus pneumoniae (a cause of pneumonia) and Fusobacteria (a cause of trench mouth and dental abscesses). However, because you don’t know if the pneumonia is caused by S. pneumonia or if the dental abscess is caused by Fisobacteria, you don’t use penicillin first.
Because penicillin selectively targets an enzyme that we humans don’t have or need, the side effects of this antibiotic are usually very mild.
Because the spectrum of penicillin has become so narrow, I do not recommend that anyone stock this antibiotic. Other antibiotics are the same price and have more than one use. Continue reading to see which antibiotics to keep on hand for strep throat.
Ampicillin was invented by sticking an amino group onto the side of Penicillin. This increased the antibiotic’s ability to penetrate into bacteria, which broadened the spectrum of this antibiotic to include some gram negative bacteria. Like penicillin, it is a beta-lactam antibiotic. Like penicillin, it works by inhibiting cell wall repair leading to bacterial cell death.
It is classified as an intermediate-spectrum antibiotic. While broader in spectrum than penicillin, it is still pretty narrow. It kills the three bacteria penicillin kills plus Group C strep (enterococcus) and the gram-negative bacteria Haemophilus influenzae, Neisseria meningitidis, and members of the Enterobacteria family (like Shigella, Salmonella, and E. coli).
Because ampicillin selectively targets an enzyme that we humans don’t have or need, the side effects of this antibiotic are usually very mild.
Ampicillin is a good first line choice for strep throat, sinus infections, ear infections, some urinary tract infections, and other respiratory infections like pneumonia. Of the available pet beta lactams, it has the best CNS (central nervous system) penetration, and so it is a good choice for meningitis.
Amoxicillin is the big brother of Ampicillin and another child of Penicillin. Like Ampicillin, it is made by adding side groups to penicillin. In Amoxicillin’s case, one side group broadens its spectrum (making it, like ampicillin, an intermediate-spectrum antibiotic) and another side group increases its absorption from the human gut. Like penicillin, it is a beta-lactam antibiotic. Like penicillin, it works by inhibiting cell wall repair leading to bacterial cell death.
It has the same spectrum as ampicillin, but it also kills Borellia (the causative agent of Lyme disease) and Moraxella (a cause of ear and sinus infections) and Heliobacter pylori (the cause of bleeding stomach ulcers). Amoxicillin is used for basically the same infections as ampicillin with the addition of being effective against lyme disease and stomach ulcers.
Because amoxicillin selectively targets an enzyme that we humans don’t have or need, the side effects of this antibiotic are usually very mild.
If I had to pick one of the three penicillins to stock, Amoxicillin would be the one. It has a broader spectrum than Penicillin (without being too broad) and is better absorbed from the stomach than Ampicillin.
Also known as Keflex in the retail world, Cephalexin  is a first generation Cephalosporin. After Penicillin was discovered, mold scientists went looking at other molds to find other antibiotics (a process called bio-prospecting), and it was thus that the Cephalosporins were discovered.
They are closely related to the Penicillins in that they have a beta-lactam ring and act by inhibiting cell wall repair. Like the penicillin family, they are most effective against bacteria with thick cell walls (Gram positive) and are intermediate in spectrum. They are effective against streps (so this is a fine choice against strep throat) and the staphs. However, unlike the penicillins, they are more resistant to bacterial defenses and so work against more and different bacteria. This is especially important for one reason– Staphlococcus aureus.
Staph aureus (which I will just call Staph from now on, even though there are many other strains of Staph) is a common and very aggressive bacteria that is the cause of many infections. Staph is found on our skin and in our noses, and as long as it stays there it does not cause many problems. However, if you get a little cut or scratch, staph may get in and make an infection. STAPH IS THE #1 CAUSE OF WOUND INFECTIONS WORLDWIDE. It can cause small abscesses if your immune system gets it walled off fast enough, but if not you get more severe infections like cellulitis, necrotizing fasciitis, sepsis (infection traveling in the bloodstream), osteomyelitis (infection of the bone), endocarditis (infection of the heart), or meningitis (infection of the spinal cord). Obviously, many of these can lead to death. Being in the nose (part of the respiratory tract), it can also cause sinusitis and pneumonia. Staph was one of the first bacteria to develop a resistance to the penicillin family of antibiotics. Worldwide today over 80% of Staph strains are immune to penicillin, and in some areas as many as 97% of strains are resistant. However, they are not resistant to Keflex! So this is an antibiotic you really want to keep on hand.
Keflex is first line for infections by Streps and Staph, including skin abscesses, boils, folliculitis, mastitis, mild cellulitis, impetigo, erysipelas, and strep throat. It can also be used for ear infections, respiratory infections, and UTI’s, but it is not the best choice for these infections.
Three important notes: First is that Keflex treats regular Staph aureus, but it does not treat Methycillin Resistant Staph Aureus (MRSA). Keep reading to see what antibiotic you will need to treat that. Second is that it does not penetrate into the brain and spinal cord. So it is a very poor choice for meningitis. Third is it has a fairly short half life and usually needs to be taken three if not four times a day to get best effect.
Because Keflex selectively targets an enzyme that we humans don’t have or need and because it doesn’t wipe out all your gram negative gut bacteria, the side effects of this antibiotic are usually very mild.
In a TEOTWAWKI  scenario, I foresee a lot of manual labor and violence. Both of these things lead to cuts, scratches, and puncture wounds, which means a lot of staph infections. This means you will need Keflex.
Now for something completely different– an antibiotic that isn’t a beta-lactam! Ciprofloxicin belongs to the Fluoroquinolone family of antibiotics, which were discovered by accident in the lab by a chemist trying to make malaria medication, but they sure work.
Cipro works by inhibiting bacterial Topoisomerase enzymes, which makes the bacteria unable to reproduce by blocking DNA replication. This works in both gram positive and gram negative bacteria. Bacterial resistance to Cipro is increasing and spreading, but at this moment in time is still pretty rare.
Cipro is a broad-spectrum antibiotic that kills a wide variety of gram positive and gram negative bacteria. It kills Staph aureus and Pseudomonas– two bacteria that are resistant to many other antibiotics. Because it is so broad in spectrum, it is not generally recommended for less complex infections where a narrower spectrum antibiotic would work. You don’t want to use this for a strep throat or simple skin abscess, if you have Keflex on hand.
Cipro is considered the first line agent for complicated UTI’s and kidney infections, bone and joint infections, typhoid, prostatitis, abdominal infections, gonorrhea, plague, and anthrax. It is also frequently used for infections acquired in the hospital where resistances are more likely. It can also be used for sinus infections, community acquired pneumonia, strep throat, or ear infections, but it is generally considered a little too strong for these infections. Most MRSA bacteria will respond to Cipro, but resistance is developing, and there are better choices. Cipro also penetrates the blood brain barrier well and so is a good choice for meningitis.
Like any medication, Cipro is not without potential side effects, and in Cipro’s case there is a big one. In fact, it carries a Black Box warning because of it. Cipro is associated with tendonitis and tendon rupture. The risk is increased if you are over 60 and/or on steroids. It’s rare (0.1% chance or one in a thousand), but being on Cipro makes it three times as likely compared to the general population. Also, the tendon that ruptures most often is the Achilles tendon that connects your heel with your leg. So think long and hard about taking this drug, especially if it is for something less severe. Getting through the wasteland as a cripple will not be easy.
Having Cipro on hand is a good idea, though. It will treat some things nothing else will, but it should not be used frivolously. Other antibiotics will often do the same job with fewer side effects and won’t put your tendons at risk.