Eric Bakker N.D.April 30, 2022
Only 8 Mins!

Antibiotics, also known as antibacterials, are medications that destroy or slow down the growth of bacteria. They include a range of powerful drugs and are used to treat diseases caused by bacteria. Antibiotics cannot treat viral infections, such as cold, flu, and most coughs. This article will explain what antibiotics are, how they work, any potential side effects, and antibiotic resistance.


Antibiotics have been used extensively since the late 1940’s to treat patients with infectious diseases and there is no doubt that these pharmaceutical drugs have greatly reduced the previously high rates of illness and death from even simple infectious disease. But as we all know, antibiotics have been used so widely and for such a long period of time that bacteria these antibiotics were designed to kill have in fact adapted to them, making these kinds of drugs much less effective. Each year in America alone, over 2 million people become infected with antibiotic-resistant bacteria, and around 25,000 people die each year as a direct result of these infections that have become drug-resistant.

A publication called Science News in the 1950’s ran a story1 that antibiotics could do a lot more than ‘cure many diseases’. New experiments conducted on animals al Lederle Laboratories in the early 50’s cast a ‘spectacular new role for antibiotics’ as a ‘livestock growth promoter’. Scientists found that when they gave pigs antibiotics mixed in with their food that they could increase meat yields by up to a staggering 50 percent.

Antibiotics important to medicine are still being used today by veterinarians in different countries to promote animal growth, a practice which been strongly linked to the increasing antibiotic resistance in humans. Almost 50 years ago (1966) the editors of the New England Journal of Medicine2 warned that if science continued to ignore the reality of bacterial resistance, they would “find themselves back in the pre-antibiotic Middle Ages.” In the early 1970’s health-conscious people began to lobby against the practice of feeding animals “sub-therapeutic” doses of antibiotics that fostered bacterial resistance in meat-eating humans. And as usual, for every health conscious there is always the scientific sceptic who can prove through ‘controlled studies’ that there is no evidence to suggest any link between the two, and in 2015 scientists are still arguing about the dangers of bacterial resistance as the debate rages on regarding antibiotics in animal feed.

On average, New Zealanders eat about 31kg of chicken each per year and chicken has been the number one choice for protein for the past ten years at the supermarket1. Consumption of chicken meat has more than doubled since accurate records began in 1986 when annual consumption was just 14kgs. All commercial poultry in NZ and Australia contains antibiotics. Antibiotics2 have been widely used in meat, milk and egg production in New Zealand since government approval in the 1960’s. All those who consume commercial eggs, dairy products or meats in Australia and NZ will be consuming antibiotics, detrimental to the beneficial micro-flora.

A staggering 30 million pounds of antibiotics were sold in 2011 in the US alone for meat and poultry production3, compared with the 7.7 million sold for human use and the number is on the rise. We have good reason to believe that similar large amounts of antibiotics are being used in Australia and New Zealand both for animals as well as for humans.

Gram Positive and Gram Negative Bacteria

Bacteria are generally divided into two distinct classes – The gram-positive and gram-negative bacteria. The word “Gram” is derived from the Gram Stain test that involves adding a violet coloured dye to bacteria. Gram-positive bacteria will remain violet when stained whereas the gram-negative bacteria will not be coloured violet but rather appear as red or pink coloured. Gram-positive bacteria tend to respond positively to antibiotics as well as antibodies than gram-negative bacteria, because their cell wall tends to be much more permeable to the effects of antibiotics or antibodies. The bacteria responsible for MRSA and acne are examples of Gram-positive bacteria, whilst those responsible for Lyme disease and pneumonia are examples of Gram-negative bacteria.

Types of Antibiotics

Even though there are more than 12 types of antibiotics your doctor may use, the majority of prescriptions of antibiotics will generally be a handful of different drugs. I have chosen the six most common classes of antibiotics for this article as they represent over 75 percent of what your doctor would commonly prescribe.

Each antibiotic is effective only for certain types of infections, and a doctor will generally choose an antibiotic based on the most likely bacterial cause of the infection, and in some cases lab tests may help to assist with the choice of antibiotic.

A – The β-Lactams Class (most widely used of all antibiotics – especially amoxicillin)

1 – The Penicillins (amoxicillin is most popularly prescribed antibiotic overall, followed by flucloxacillin) The β-Lactams class of antibiotics is probably the most widely prescribed type of antibiotics in most Western countries. All beta-lactam antibiotics contain a beta-lactam ring; and they include the penicillins and cephalosporins. The first to be discovered was penicillin in 1928 by Dr. Alexander Fleming. Beta lactams interfere with the synthesis of peptidoglycan, a structural component of the bacterial cell wall and are most always used against gram-positive bacteria. Bacteria can outsmart these drugs develop resistance via several mechanisms, including the production of specific enzymes that break down the beta-lactam ring. It is used to treat many different types of bacterial such as ear infections, bladder infections, pneumonia, gonorrhea, and E.coli or salmonella infection. Amoxicillin is also sometimes used together with clarithromycin and lansoprazole (Prevacid) in what is know as a “triple-therapy” to treat Helicobacter pylori infection.

2 – The Cephalosporins (cephalexin (Keflex), Cephalosporin antibiotics are a class of are β-Lactam antibiotics used to treat pneumonia, strep throat, staph infections, tonsillitis, bronchitis, otitis media, various types of skin infections, gonorrhea, urinary tract infections. They are also commonly used pre & post surgery. Cephalexin can also be used to treat bone infections. Ceplhalosporins are grouped into “generations” based on their antimicrobial properties. Each newer generation has a more potent and broader-spectrum activity than the generation before it, but is also increasingly expensive. Antibiotics in the fourth generation can even cross through the blood-brain barrier and effectively treat bacterial meningitis. Cephalosporin doesn’t usually cause as many side effects as other antibiotics do.

β-Lactams Side Effects : diarrhoea, nausea, mild stomach cramps or upset. Approximately 5–10% of patients with allergic hypersensitivity to penicillins will also have cross-reactivity with cephalosporins. Cephalosporin antibiotics are contraindicated in people with a history of allergic reactions (urticaria, anaphylaxis, interstitial nephritis, etc.) to penicillins or cephalosporins.

B – The Macrolides (second most widely used antibiotics – especially erythromycin)

Macrolides include erythromycin, clarithromycin, and azithromycin. These drugs are similar to Beta-lactams in that that are mainly used against gram-positive bacteria but is this case they act in a bacteriostatic manner in that they prevent bacterial growth by inhibiting protein (ribosome) synthesis. They tend to have more broad-spectrum activities that penicillin. They are losing increasing ground as an increasing amount of bacteria are becoming resistant to this class of antibiotics.

Macrolides are used mainly for different kinds of respiratory infections and are mainly used to treat sinusitis, pharyngitis, bronchitis, skin infections as well as genital and gastrointestinal tract infections.

Macrolide Side Effects: nausea, vomiting, and diarrhea; infrequently, sometimes there can be temporary hearing impairment. Azithromycin has been associated with allergic reactions, including angioedema, anaphylaxis, and skin reactions. Oral erythromycin may be highly irritating to the stomach and has caused many of my patients to complain to their doctor. Like most antibiotics, macrolides should be used with caution in patients with liver dysfunction.

C – The Aminoglycoside Class (family of more than 20 antibiotics)

There are many different aminoglycoside antibiotics such as gentamicin, neomycin, streptomycin and tobramycin. A fungus called Streptomyces griseus found to produce a substance with antibiotic property that causes bactericidal death was discovered by Selman Waksman who named the substance ‘streptomycin’. Waksman went on to receive a Nobel prize in Medicine and Physiology in 1952 for his discovery of streptomycin. It was in fact Waksman who coined the phrase ‘antibiotic’ in 1942. Aminoglycosides are bactericidal and work by stopping bacteria from making proteins by interfering with ribosomes found in bacterial cells. This class of powerful antibiotics is used to treat infections caused by gram-negative bacteria such as serious infections, septicemia, tuberculosis, etc.

Aminoglycoside Side Effects and Bacterial Resistance: Aminoglycosides work well, but bacteria become resistant to them, and because they are poorly absorbed through the digestive system when given orally they need to be given intravenously for infections increasing their potential for side effects. These powerful drugs are given for very short periods of time only (no more than 3 days) and because they are considerably toxic; their use needs to be very carefully considered. The major irreversible toxicity of aminoglycosides is damage to the ear and hearing (ototoxicity) as well as kidney damage (nephrotoxicity).

D – The Sulfonamides (sulfa-drugs – the first commercially available antibiotic)

This class of antibiotics includes cotrimoxazole (Bactrim) and trimethoprim. The first commercially available antibiotic was a sulfonamide and was developed in 1932 (Prontosil). Many of this broad-spectrum class have been developed since, capable of a broad spectrum action on both gram-positive and gram-negative bacteria. Sulfonamides work by disrupting the production of di-hydrofolic acid (a form of folate), preventing bacteria from producing proteins thereby disrupting growth and reproduction of bacteria. Today they are less commonly used due to bacterial resistance, as well as their powerful ability to induce hepatotoxicity. Certain kinds of sulfonamides such as sulfasalazine are also used with ulcerative colitis.

Aminoglycoside Side Effects: dizziness, headache, lethargy, diarrhea, anorexia, nausea, vomiting, and serious skin rashes. Hepatotoxicity can occur, especially if patient drinks alcohol as well.

E – The Quinolones (the most common contributor to antibiotic resistance)

Quinalones include ciprofloxacin (Cipro) and levofloxacin. This broad-spectrum class of antibiotics are one of the newest and were developed in the1960’s. Their generic name often contains the root word “floxacin”, and unlike other antibiotic classes these synthetic antibiotics and not made from bacteria or yeasts and work by interfering with the bacteria’s ability to make DNA, inhibiting bacterial reproduction. Because of their excellent uptake into the body, quinolones are generally administered orally. Drugs like Cipro are commonly used to treat urinary tract infections, skin infections, and respiratory infections (such as sinusitis, pneumonia, and bronchitis). They are generally used for hospital-acquired infections when a doctor suspects resistance to older antibiotic classes.

Quinolones have also been widely used for veterinary purposes, a use that has been criticized for increasing the development of antibiotic-resistance. They were they most commonly prescribed antibiotic is 2002 in America and their wide overuse (even routinely given for viral infections) is thought to be one of the most significant contributors leading to widespread antibiotic-resistance.

Quinolone Side Effects: Several of the newest quinolones have been withdrawn because of toxicity; they include trovafloxacin (severe hepatic toxicity), gatifloxacin (serious hypoglycemia and hyperglycemia), grepafloxacin (cardiac toxicity), temafloxacin (acute renal failure, major hepatotoxicity, hemolytic anemia, coagulopathy, and acute hypoglycemia).

F – The Tetracyclines (becoming less popular due to increasing resistance)

Tetracyclines include tetracycline and doxycycline. These are broad-spectrum antibiotics and are active against both gram-positive and gram-negative bacteria. Like the sulfonamides, they inhibit protein synthesis, inhibiting growth and reproduction of bacteria.

Tetracycline is often used for acne (sometimes continuously for months and months), chronic bronchitis, and for the treatment of syphilis and gonorrhoea in patients allergic to penicillin. It is also commonly used in conjunction with other antibiotics such as penicillin as part of a multi-drug triple-therapy regimen for Helicobacter pylori eradication. Doxycycline is also used to treat many different bacterial infections including acne vulgaris and acne rosacea (blemishes, lumps & bumps and others acne-like lesions), urinary tract infections, periodontitis and dental abscesses, gonorrhoea, and chlamydia, mycoplasma, rickettsia and others unlisted infections.

They must be taken two hours at a minimum away from eating because they can readily bind with foods, reducing their absorption. Tetracycline use is decreasing due to increasing incidences of bacterial resistance; however, but many doctors still use them with acne, UTIs, as well as respiratory tract infections.

Tetracycline Side Effects: include constipation, diarrhea, cramps, bloating and gas as well as sore mouth and especially the tongue (can last for months or even much longer). You will need to be careful about sun exposure after taking tetracyclines because they are know to cause ‘photosensitivity (an increased risk of sunburn after UV light exposure). This may be an important (and often overlooked) consideration for holidaymakers intending to take long-term doxycycline on their vacation as malaria prophylaxis. Tetracyclines should not be given to young children who are developing teeth because they are know to cause tooth discoloration. They can also cause allergic reactions, although penicillins are more likely to cause stronger allergic reactions and have even been linked to anaphylaxis. In rare cases, tetracyclines have been linked to severe headaches and vision problems, signs of increased intracranial blood pressure.

Before Antibiotics

For simplicity, I have used the 1940’s as a dividing line between the pre-antibiotics and the antibiotic era. Before the 1940’s there were in fact no antibiotics, how did parents handle sick kids? What did people do with infections? How did health-care professionals actually treat infections? A common-sense approach was not to treat the infection but to let the body fight in naturally. Doctors in bygone days would encourage the body to build up natural resistance and only when the body was clearly not winning the battle was any intervention required.

People depended primarily on herbal medicines and various folk cures, most countries had their own form of herbal medicine and a doctor or herbalist was ready to help in the treatment of infections. In most cultures, the empirical knowledge of cultivating, wild crafting and using herbal medicines was passed down from one generation to the next. Doctors depended to a great extent on natural substances and even used elements such as iron, cannabis extracts and antimony. Most doctors in Germany were trained in homeopathic medicine and from the 1840’s through to the 1920’s homeopathic medicine was extremely popular throughout Europe and North America. In the early 1900’s though, the AMA (American Medical Association) gained strong political lobby and shut down nearly all of the homeopathic hospitals and colleges. By 1920, only 7 of the many hundred establishments remained, and today they are all but gone. It is important to understand the use of ‘mother tinctures’ by homeopaths; a mother tincture is a potent solution of a plant-based substance and alcohol made according to standards set by the HPUS (Homeopathic Pharmacopeia of the United States). Homeopathy today is just about gone, it happened one hundred years ago and it is happening all over again. Perhaps in the future when the ridiculous profits are no longer associated with healing will it make a significant comeback. Most all ‘medical research’ today is still sponsored by pharmaceutical interests and medical students are taught pharmacology as the primary route of treating patients.

Herbal medicines were still being regularly used even in the mid 1930’s my medical doctors according to my volume of “Treatment In General Medical Practice” (Articles for the British Medical Journal, 1936) Diseases such as albuminuria and nephrosis were treated in 1936 with extract of licorice.4

Before the 1940’s, the treatment of common infections were depended on:

  • Herbal medicines
  • Homeopathic medicines
  • Traditional folk cures
  • Common sense

The Dangers Of Routine Antibiotic Prescribing

In my clinic I see patients on a daily basis who have been affected by antibiotic drugs. A common scenario is that the patient was treated in the past for acne for tetracycline or trimethoprim for a UTI, and they have never been well since. Candida yeast infections become a reality for all too many patients.

It is not uncommon to find that a child with a behavioural problem was treated routinely with antibiotics in the past, for example an ear infection, a cough or a sore throat, and often times they will have been recurrently. Soon thereafter, changes may begin to occur. There could be developmental delays, speech development may stop, and within a few weeks or months the child may become unresponsive and lose interest in his parents and surroundings. Concerned parents then take the child to various specialists, and finally come up with a diagnosis of autistic spectrum disorder. Worried mothers may have their children in and out of medical clinics and unfortunately there are still doctors who still routinely prescribe antibiotics (even for the tiniest of cuts and abrasions that respond to Tea Tree oil), despite the fact that not only the malevolent bacteria are destroyed but also the friendly bacteria such as Lactobacillus and Bifidus species.

The yeast remaining behind now thrives, as they are not susceptible to the influences of antibiotics (some classes of antibiotics in fact are made from yeasts such as Penicillin), and with recurring prescriptions the bacteria left behind become more increasingly resistant to antibiotics.

Antibiotic Resistance

Post 1940’s, the treatment of common infections showed an increased reliance on sulpha drugs and antibiotics. While antibiotics are potentially life saving and present an amazing advancement in medical science, their time is just about up. We were promised that the scourge of infectious disease would be gone for all-time and that all humans would end up ‘living in an infection-free world’. The reality is that bacterial resistance is advancing at an alarming rate to the point where doctors are seriously concerned about our future as a species on this planet. Antibiotics are being rendered useless by the very bacteria they were intended to destroy. Antibiotic-resistant bacteria sicken more than two million Americans each year and account for at least 23,000 deaths. The main cause is the chronic overuse of antibiotics.5

As a result of increasingly resistant bacterial strains, increasingly stronger antibiotics need to be created – creating even more resistant bacteria. However, the break neck speed at which resistance is developing globally is considerably faster than the pace at which drug companies can manufacture new classes of antibiotics.

I encourage you to look at the following web-links and read the reality of how useless these ‘wonder’ drugs will be in the future. It makes you wonder why more research and money wasn’t invested originally in the early days into the very best natural medicines to counter infectious disease.

Allergic Reactions

Allergic reactions to antibiotic reactions can range from mild allergic reactions to severe and debilitating adverse events. Antibiotic side effects are extremely variable and can vary from patient to patient and are also quite different from antibiotic to antibiotic. There is however some common antibiotic side effects that may occur within the various antibiotic classes.

Acute allergies or hypersensitivity reactions to an antibiotic are in fact one of the most common drug-related side effects leading to ER admission. Almost 50 percent of ER visits to many hospitals are due to antibiotic reactions in the penicillin class of drugs, and a further percentage are due to a wide variety of antibiotic drugs used to treat a wide variety of infections. Children under one year of age have been found to have the highest rate of antibiotic related side effects.6

Mild reactions may result in a skin rash, and I see these commonly in my clinical practice after a patient is prescribed an antibiotic. They are then treated with another ‘anti’ drug, an antihistamine, to counter the response. More severe allergic reactions can include anaphylaxis leading to wheezing, shortness of breath, hives and swelling of the face including the tongue and lips. Such medical emergencies need immediate ER attention or they could result in death.

My mother-in-law had a severe anaphylactic reaction several years ago after taking only one capsule of erythromycin for a cough that almost cost her life, and it was only the quick thinking by her doctor that had saved her.

Digestive Problems

Antibiotics almost always disturb the intestinal flora, especially the Lactobacillus acidophilus and Bifidobacterium bifidus species. Such disturbances have been linked to irritable bowel syndrome and inflammatory bowel disease like ulcerative colitis and even colon cancer. In my clinical experience, antibiotics nearly always lead to some form of digestive problem and problems can range from short term (4 to 6 weeks) right through to “never been well since” (NBWS) an antibiotic prescription, even twenty years or more after the drug was prescribed. It is important to always therefore establish if a person’s digestive problem started after they were prescribed an antibiotic or if they have NBWS.

Research has shown that 25 percent or even more of all patients who have been taking an antibiotic go on to develop antibiotic-associated diarrhea. The eradication of the beneficial bacteria often results in the overgrowth of infectious bacteria such as Clostridium difficile as well as Candida albicans.

Yeast infections (tongue & oral thrush, vaginal, jock itch, etc.)

Antibiotics are known to change the normal flora balance in the mouth, throughout the GI tract, vagina, groin, axilla, leading to an overgrowth of potentially many different fungal species. Candida albicans is a common fungus normally present in small amounts in the GI tract, mouth, vagina, and even on the skin and when kept in balance does not generally cause any disease or symptoms. Candida however may take over when there is limited competition from bacteria due to antibiotic treatment.

After having treated countless patients over the years with gastrointestinal problems ranging from mild to most severe and debilitating as well as many women suffering from chronic vaginal thrush and men with ‘incurable’ cases of jock itch, I have come to the conclusion than in most all these cases the patients had a history of antibiotic use.

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