Pharmaceutical Microbiology


Written by MicroDok

Antibiotic resistance is a phenomenon that occurs when bacteria are not killed or inhibited by usually achievable systemic concentration of an antibiotic which is supposed to prevent their harmful effect to a host. It is a global health problem that has bedeviled our health sector worldwide. There emergence and increase is gradually eroding the efficacy of drugs used in clinical medicine for the treatment of infectious diseases. Prior exposure to antibiotics places a kind of selective pressure on bacteria, thus making them develop resistance to a particular drug over time. Microbes or bacteria can also develop resistance following changes (mutation) in their DNA. Antibiotic resistance is of many types including extended spectrum beta lactamase. Extended spectrum beta lactamases (ESBLs) are a group of β – lactamase enzymes that break down and cause resistance to beta-lactam antibiotics including penicillins and cephalosporins, thus rendering them ineffective for treatment in vivo.

They are Multidrug resistant organisms, extending their resistance to both β – lactams and non- ­beta lactams like aminoglycosides and quinolones. ESBLs are plasmid-mediated and can be exchanged between bacteria via genetic transfer. They carry tremendous clinical implications since most of the drugs used in therapy are rendered ineffective by them. It is therefore pertinent that the clinical microbiology laboratories all over the world detect ESBL production in clinical isolates following the CLSI standards of detecting them. This will help to guide therapy, prevent the morbidity and mortality caused by antibiotic resistant bacteria – thereby putting us on the road map to curbing and containing antibiotic resistance in our world of today.

In recent times, antibiotic resistance of pathogens to drugs (antibiotics) directed towards the degrading properties of microbes in vivo has been on the increase both in the community and in the hospital. Antibiotics are exceptionally vital in clinical medicine for the treatment of bacterial related infections, but unfortunately bacteria are capable of developing resistance to them. Antibiotic resistance is a global health problem that has bedeviled our health sector worldwide, affecting both the developed and developing countries of the world. They make infectious diseases very difficult to treat. The emergence of antibiotic resistance is a complex problem that is driven by many interconnected factors, of which the use and misuse of antimicrobial agents (antibiotics, antiseptics, disinfectants, and preservatives) amongst other factors, is the main driving force for the development of resistance.

Antibiotic resistance occurs when bacteria change in some way that reduces or eliminates the effectiveness of drugs, chemicals or agents designed to cure or prevent the infection. Thus, the bacteria survive and continue to multiply causing harm and havoc in the patient (host) taking the drug. There has been a very great concern that the “antibiotic era” might be coming to an end – firstly, because the rate of production of new drugs has diminished greatly and, secondly, because microbes (viruses, bacteria, fungi, protozoa) are showing great inventiveness in devising mechanisms for circumventing the inhibiting and killing properties of drugs (antibiotics) directed towards them. Deaths from acute respiratory infections, diarrheal diseases, measles, AIDs, malaria and tuberculosis account for more than 85% of the mortality from infection worldwide.

Resistance of microbes to first-line drugs causing these diseases according to the WHO ranges from zero to almost 100 % and in some cases, resistance to both second – and third – line drugs is seriously compromising treatment outcome. A major example is extended spectrum β – lactamase (ESBL) – producing bacteria which is resistant to virtually all beta – lactam drugs and some non – beta lactam drugs. Antibiotic resistance though a natural biological phenomenon, has in no doubt lead to the loss in the efficacy of some important drugs (especially the beta-lactams) from our therapeutic armamentarium.  Nobody is to be blamed for this plethora of menace that is gradually eroding the efficacy of our drugs, since the introduction of every antimicrobial agent into clinical practice at one time or the other has been followed by the detection in the laboratory of strains of microorganisms that are resistant to these antimicrobial agents.

In containing antibiotic resistance in both our community and the hospital, a good and adequate routine diagnostic antimicrobial susceptibility testing in the microbiology laboratory is paramount. They should be charged with the responsibility of detecting antibiotic resistant strains of microbes (especially ESBL-producing bacteria) in the hospitals and in the community using internationally recognized protocol as outlined by the Clinical Laboratory Standard Institute, CLSI (formerly National Committee for Clinical Laboratory Standards, NCCLS) guideline. Data emanating from such studies should be made available and harnessed properly by all stakeholders in order to develop a road map for the proper control and eradication of antibiotic resistance from our world. Therefore, it is ripe for us to close the door on antibiotic resistant strains of bacteria before we wake up someday and find out that the only weapon (antibiotics) we have against bacterial related diseases have left us.


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