|LETTER TO THE EDITOR
|Year : 2016 | Volume
| Issue : 7 | Page : 94-97
Learning pharmacology by metaphors: A tale of aminoglycosides
Gurudas Khilnani1, Ajeet Kumar Khilnani2, Rekha Thaddanee3
1 Department of Pharmacology, Gujarat Adani Institute of Medical Sciences, Bhuj, Gujarat, India
2 Department of Otorhinolaryngology, GMERS Medical College and Hospital, Patan, Gujarat, India
3 Department of Paediatrics, GMERS Medical College and Hospital, Patan, Gujarat, India
|Date of Web Publication||2-Nov-2016|
Ajeet Kumar Khilnani
Department of Otorhinolaryngology, GMERS Medical College and Hospital, Patan, Gujarat
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Khilnani G, Khilnani AK, Thaddanee R. Learning pharmacology by metaphors: A tale of aminoglycosides. Indian J Pharmacol 2016;48, Suppl S1:94-7
|How to cite this URL:|
Khilnani G, Khilnani AK, Thaddanee R. Learning pharmacology by metaphors: A tale of aminoglycosides. Indian J Pharmacol [serial online] 2016 [cited 2020 Mar 28];48, Suppl S1:94-7. Available from: http://www.ijp-online.com/text.asp?2016/48/7/94/193319
A need is felt to restructure pharmacology curriculum with stress on integrated/interdisciplinary teaching. One of the objectives laid down in the curriculum of pharmacology, by the Medical Council of India, is to prescribe drugs rationally by selection based on suitability, tolerability, efficacy, and cost. This can be achieved by acquisition of knowledge of important aspects of drugs such as nature and source, availability of a number of drugs in the class, systemic effects including mechanism of action, pharmacokinetic comparison of different members of the class, adverse drug reactions, and comparative cost. Often, students find it difficult to remember, such “must-know details” of several drugs that should enable them to select a suitable one, when taught by conventional classroom teaching method. Learning can be facilitated by giving homologous/analogous examples. Specific analogical language comprises culinary and other analogies and has been used in dermatology and clinical medicine., We have constructed a metaphoric text of aminoglycoside with the objective to provide required knowledge in a simplified and easy-to-grasp form that stimulates interest of students. We have tried to incorporate horizontal integration with microbiology using morphological and cultural characteristics of enteric group of organisms as well. We realize that preparing such metaphors requires a lot of imagination and innovative thinking, getting inspirations from bowls and pillboxes. Nevertheless, such metaphors can be useful teaching tools for MBBS students learning rational use of medicine.
Aminoglycosides, traditionally friends of Homo sapiens, are foes of pathogenic intestinal microorganisms. Often, when one of the members of aminoglycoside family is present, then, one would not find any of members of other group (Enterobacteriaceae). These two groups distanced so much from each other that one new little about family details of other group. Nevertheless, man, the common host for both families, knew every detail of both groups and often took advantage of their rivalry! It so happened that both families were invited to attend a farewell dinner organized by Streptomyces family.
Ms. Escherichia (coli), Ms. Klebsiella, and Mr. Pseudomonas were delighted to participate in the functions. Of aminoglycoside family, Mrs. Streptomycin, Ms. Gentamicin, and Mr. Amikacin gleefully agreed to attend the function. Mr. Waksman, the parish priest, instructed them to behave gently and nicely with the opponents despite family feuds. In fact, he knew that those microbes carried with them clandestine weapons, known as “plasmids.”
For the occasion, Ms. Escherichia and Ms. Klebsiella wore Fimbriated frocks. Ms. Escherichia walked with deliberate swings due to? Peritrichate flagella. Ms. Klebsiella wore a headgear (Capsule) which gave an appearance of halo around her face! Mr. Pseudomonas, visibly slender but actually powerful (pathogenic), adorned himself with Polar flagellum and smeared his face with Mucoid slime that emitted “Grape-like odor.” He was known for exhibiting colorful (brown, green, and red) cultural shows. Ms. Klebsiella was expert in making Currant jelly dessert.,
Madam Streptomycin, the eldest of the daughter of Streptomyces griseus family, had been too cruel against microbes in the past but has become sober and weak with advancing age and, thus, three microbes were little afraid of her. Ms. Amikacin was daughter of Mrs. Kanamycin (who was born after Streptomycin in 1957) and was known for her killing instincts against opponents having hidden weapons (plasmids) as well (organisms resistant to other aminoglycosides are susceptible to it).
Both groups met at the gate of the venue. There were many other guests. Madam Streptomycin exchanged greetings with Mr. Mycobacteria and Mrs. Haemophilus. Ms. Gentamicin grinned at Ms. Escherichia, Klebsiella, and Pseudomonas. Ms. Amikacin shook hands with Mr. Proteus and Mr. Pseudomonas. Then, welcome drinks were served to everyone. All cheered the drinks to toast for the health. After a few sips, all members of both families were relaxed and set around a table in a dimly lit corner and gossiped on several contemporary issues forgetting their rivalry.
After a brief introduction, Ms. Escherichia was first to ask, “Many of your members are found in high concentration in urine where I prefer to reside. How is that?”
“See, we are not much inactivated in human body and manage to reach in urine.” “Furthermore”, Mrs Streptomycin elaborated, “being water-soluble, we cannot get across the intestinal mucosa. So man uses us by injectable route.”
“That way you are different than other antibiotics” commented Ms. Gentamicin. She nodded.
Mr. Pseudomonas then asked from Ms. Amikacin, “Why do suffix yourself with ‘–micin’ while Madam Streptomycin uses ‘–mycin’?”
Ms. Amikacin eagerly responded, “This is because –mycins such as Streptomycin, Tobramycin, and Kanamycin are obtained from Streptomyces fungus whereas –micins such as Gentamicin, sister Sisomicin, and brother Netilmicin originate from Micromonospora clan. This identifies us with the source of origin!”
“That is great” said Mr. Pseudomonas.
“Do you know?” Mrs.Streptomycin elaborated further, “That we are born with 2 or more (amino-) sugars (Paromomycin and Neomycin have 3 sugars) but are not as sweet (are toxic to microbes and human beings).”
“That we have often experienced” Ms. Klebsiella retorted.
“One of my friends, Mr. Neisseria gonorrhoea, had a very bad encounter with Spectinomycin. Does anyone of you know about it?” asked Ms. E. coli.
“Mr. Spectinomycin is a distant relative of streptomycin (both are aminocyclitols) but has no sugar! He usually does not mix with many of us (does not cause misreading of RNA in microbes). However, he is deadly dangerous against N. gonorrhoea and knocks it down with a single blow (single-dose intramuscular)” replied Mr. Gentamicin.
“Oh, that is the reason” exclaimed Ms. E. coli!
“And beware of Mr. Gentamicin” said Mr. Pseudomonas to other friends. “Often, I have been the victim of his assault and in bargain, I had to import (acquire) chemical armoury (inactivating enzymes) to defend against his massacre. In fact, I have learnt to resist Tobramycin, Amikacin, Kanamycin, and Netilmicin while by escaping gentamicin assaults by harboring such weapons (Gentamicin resistance indicated cross-resistance to Tobramycin, Amikacin, Kanamycin, and Netilmicin).”
“And what about Streptomycin?” asked Ms. E. coli.
“You will be amazed to know that our eldest member, Streptomycin, is endowed with power to kill enemy even when it is well-armored with plasmids and alike,” said Ms. Gentamicin (gentamicin-resistant strains of enterococci are susceptible to Streptomycin).
Madam Streptomycin explained that they all had killer powers initially but as time passed the microbes had acquired abilities to defend against their killing action.
“May I ask you a question but at the outset I may say that please do not reply if it hurts you in any way” requested Mr. Pseudomonas.
“Never mind such apprehensions, you may ask us any question,” assured Madam Streptomycin.
“How do you harm and kill us?” asked Mr. Pseudomonas who was trembling.
Mrs. Streptomycin was taken aback, but as she had already absolved them, she thoughtfully replied, “We enter into your body (by diffusion) through porin channels of outer coat (cell wall) and then use your membrane carriers (bacterial cell membrane electron transport system) to reach into cytoplasm. Inside cell, we attack 30s infantry division of your ribosomes and freeze formation of right amino acid sequences (protein synthesis) needed for your survival.”
“Actually, we play havoc in your ribosomal factory and misguide workforce to disturb line management (block initiation and chain elongation), misread the map (genetic code), incorporate wrong component (amino acid) in sequence so that faulty finished products (proteins) are formed and transported to the cell membrane that finally disrupts and, thus, you perish!”
“It is awful to know all this but we too have developed mechanisms to ward off such dangers,” disclosed Mr. Pseudomonas in defiance.
“What do you mean by that?” annoyingly questioned Ms. Gentamicin.
“Often, we restrict entry inside (bacterial cells), make our ribosomes hostile to you and of course develop inactivating enzymes that weaken your killer instincts!” elaborated Mr. Pseudomonas under inebriation.
A certain degree of disbelief and doom could be seen on their faces and silence prevailed for some time.
Finally, Ms. Escherichia changed the topic.
“I may tell you an interesting fact” she said. “These human beings are amazing creatures. They indulge in so many misdemeanors and open gates for us to invade and damage their organs.” (Sexual promiscuity, bad hygiene and unwholesome diet, which predispose them to enteric infections.)
“For example, I can damage their urinary system extensively.” She elaborated further.
“I can damage their lungs,” added Klebsiella.
“And I inflict devastating injuries to humans as I am capable of growing in hospitals even in the presence of Cetrimide!” boasted Mr. Pseudomonas.
“Please do not consider us innocents that way” said Amikacin in reply. “We too can damage man’s kidneys, ears, and nervous system if they misbehave (improper drug use) with us.”
“I am capable of damaging kidneys and hearing-organs (Cochlea) too much,” she elaborated.
“Mrs. Streptomycin is cruel on balancing organs of human ears in particular. She silently gets into inner ear in high concentration and produces irreversible damage to vestibule. It is pity to watch such an individual (mostly elderly) under her influence having double vision, difficult stance in dark and walking with a lurch (ataxia) as if he has drunk deadly! ? It also causes deafness and person to suffer from a sense of painful ringing in ears (tinnitus),” she continued.
“And what about Ms. Gentamicin?” asked Mr. Pseudomonas.
“She is one member bestowed with power to destroy cells of balancing organs (Vestibular organs) and proximal tubular cells of kidneys much more than others. Man is so much afraid of this effect that he has now devised strategies to reduce our effect on kidneys,” said Madam Streptomycin.
“You are talking about single daily-dose therapy, I suppose,” said Amikacin.
“Yes, exactly and in addition, man uses dose calculations based on their kidney function for administration of gentamicin and other members,” answered Mrs. Streptomycin, “but even that does not completely eliminate the damage!”
“Is not our aggression the reason for that?” commented Ms. Gentamicin.
“Not exactly,” replied Ms. Amikacin, “Many human-related factors (advancing age, diabetes, liver disease, sepsis) determine oto- and nephron-toxicity. Furthermore, neomycin and framycetin, our closer cousins, are so dangerous in causing kidney and ear damage that humans refrain from their systemic use.”
“And you may also know that we can block myoneural junction and weaken their muscle power,” Mrs. Streptomycin confided.
“Is it that you are cruel to us only?” questioned Ms. Escherichia.
“Not at all” was the reply by Madam Streptomycin, “we can kill a large number of other bugs such as Mycobacteria, Pasteurella, Brucella, enterococci, and Mycoplasma.”
“Dear Madam, can you enlighten me from whom should I be afraid the most?” Mr. Pseudomonas prayed to Ms. Streptomycin.
She responded, “As such we all can harm you, but beware of Mr. Tobramycin as he is 4–5 times stronger than gentamicin to smash you. Furthermore, we can invite our bosom friends, b-Lactams and Vancomycin, to potentiate our lethal attacks against you all.”
“Oh” Microbes uttered ruefully.
Meanwhile, dinner was served and all were engaged in mouthfuls of delicious delicacies including pea soup (stools), Currant jelly (sputum), and anchovy sauce (pus). Satiated, they thanked the host for a sumptuous dinner and departed with a promise for peaceful coexistence! [Table 1].
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