Microbial evolution

By Dr. Ismail Muhammad Bello

You have likely heard about climate change, a pressing existential threat demanding global collaboration. However, it is not the sole concern. Antibiotic resistance is another rapidly emerging issue that demands urgent attention.

Not too long ago, the pathological basis of diseases was shrouded in mystery, often attributed to superstitions. About four hundred (400) years back, the role of microbes in disease causation was still unknown. It took the discovery of the microscope and the works of Antoni Van Leeuwenhoek to open our eyes to the unseen world – the realm of microbes – surrounding and inhabiting us.

Microbes, omnipresent and adaptable, have evolved significantly to thrive in a constantly changing world. The human connection with microbes is extensive and intriguing. Thanks to their versatility, microorganisms are instrumental in driving human technological advances through their varying applications in agriculture, environmental protection, medicine and industrial production. From drug discovery and development to their role in bioremediation, biotechnology, and the emerging field of genetic engineering, microorganisms have played a monumental role in the survival and progress of life forms on Earth, even shaping civilizations.

Nevertheless, despite their crucial role in the earth’s functions, microbes also contribute to human misery as pathogens. Despite global efforts to combat them, infectious diseases persist as a challenge, particularly in Sub-Saharan Africa where the existing weak health system grapples with a double burden of diseases – an increasing prevalence of non-communicable diseases alongside prevailing communicable diseases.

Apart from the substantial morbidity and mortality resulting from infectious diseases, the burden encompasses economic losses due to healthcare expenses and disabilities, as well as a decline in productivity. In a broader sense, infectious diseases hinder human development by adversely affecting education, income, life expectancy, and other health indicators.

While current morbidity and mortality rates remain notably high, the situation contrasts significantly with the past where certain infections, now easily treatable, were once considered death sentences or challenging to address. The serendipitous discovery of Penicillin by Alexander Fleming stands out as a pivotal moment in medical history. “Antibiotics” not only transformed the curability of many diseases but, coupled with advancements in anaesthesia, also enhanced the safety and feasibility of major surgeries.

While the term “antibiotics” holds a more specific meaning in pharmacology, commonly it refers to a category of drugs utilized in treating “bacterial” infections. Bacteria, while a significant group, represents just one class of microorganisms; others include viruses, fungi, parasites, and even prions. Antibiotics function by disrupting vital processes in microbes leading to a loss of structural integrity or functional capacity, ultimately causing them to die or halt their replication.

Antibiotics encompass a diverse group of drugs, belonging to various classes, each effective against specific types of organisms. They include the well-known Amoxicillin (Amoxil), Ampicillin-Cloxacillin (Ampiclox), Metronidazole (Flagyl), Ciprofloxacin, Amoxicillin-Clavulanate (Augmentin) and numerous others easily accessible over-the-counter in our setting. Antibiotics have played crucial roles in combatting menacing diseases like Tuberculosis, Leprosy, Gonorrhoea, Syphilis, bacterial pneumonia, acute bacterial meningitis, and many others.

The introduction of these drugs came as a huge blow to the pathogenic microbes that previously had a field day. However, in line with natural selection, they didn’t succumb passively and perceived the development as a declaration of war. Over the years, these microbes evolved, becoming insensitive to many of these drugs—a phenomenon known as antibiotic resistance.

In response, scientists discovered new drugs, tweaked some of the existing drugs or synthesized novel ones. This led to a vicious cycle, whereas new drugs are developed, these organisms adapt and become resistant. This trend persists to our present day, leading to the emergence of highly resistant strains of microorganisms that are not susceptible to most of the antibiotics used in treating the kind of infections they cause – the so-called Superbugs. 

Unfortunately, this cycle is not sustainable for mankind. The rate at which microbes adapt to our drugs is faster than the turnout of our drugs. It takes about 10-15 years to develop a new antibiotic. Not only that, studies have shown that the estimated global cost of developing a new, targeted antibiotic will cost over a billion USD ($1 Billion), making it a highly expensive and risky venture for pharmaceutical companies.

The combination of these factors has impeded innovation in the field of antibiotics. Notably, the latest discovery of a new “class of antibiotics” that has reached the market was back in 1987. Since then we have been in a “discovery void” era, and currently, there are few novel antibiotic classes in the drug development pipeline. 

In 2022, the World Health Organization (WHO) identified twenty-eight (28) antibiotics in clinical development that address the WHO list of priority pathogens, of which only six (6) were classified as innovative. The repercussions are felt globally as an increasing number of bacterial infections are becoming hard to treat, once again posing a threat to global health and development.

Undoubtedly, resistance is a natural phenomenon and will eventually develop against some antibiotics. However, the accelerated rate at which it is occurring is aided by our irrational use of these drugs. Therefore, prudent use will surely slow down the process. 

Key determinants of antibiotic resistance include antibiotic abuse in veterinary and medical practice, inadequate provision of Water, Sanitation and hygiene (WASH) infrastructure, and the effectiveness of policy development and enforcement.

Dr. Ismail is a Medical Officer at Khalifa Sheikh Isyaka Rabiu Paediatric Hospital, Zoo Road, Tarauni, Kano State.