How and why Amoxicillin is overused
Amoxicillin is a β-lactam antibiotic prescribed by physicians to fight bacterial infections. The drug does not kill bacteria, but obstructs their ability to form cells, a precondition for bacteria to proliferate (Offit et al, 1999). News about amoxicillin overuse in North America, South America, Africa, Europe and Asia is a major cause of concern for practitioners as it enhances drug resistance (Rosenblut et al, 2006). Amoxicillin’s availability as an over-the-counter (OTC) drug has enhanced its use in many parts of the world, especially in North America and Europe (Wood, 1999). In developing countries, self prescription plays a role in enhancing overuse of amoxicillin. Mostly, in self prescribing, the drug is taken for the wrong reasons, increasing instances of resistance (Abramson & Givner, 1999). In all continents, amoxicillin is prescribed more often by physicians as a good remedy for bacterial infections, making it one of the most overused antibiotics. In most parts of Europe, Asia, and North America, the drug is prescribed freely and irrationally (Mohan et al, 2004).
Amoxicillin continues to be overused all over the world since it is viewed as having a comparatively broad spectrum against many bacteria that are sensitive to its effects. The drug forms a good selection for physicians when the sensitivity of the disease-causing bacteria is unknown (Offit et al, 1999). When an organism in a severe ailment cannot be secluded, a common strategy for many practitioners around the world is to ‘cover’ for all potential bacteria using amoxicillin in amalgamation with other antibiotics, leading to its overuse (Wolf, 2003). Amoxicillin also continues to be overused due to misdiagnosis of ailments. For example, physicians continue to treat 50%-70% of patients suffering from upper respiratory tract infections (URTIs) with amoxicillin, notwithstanding the fact that majority of these ailments have a viral aetiology (Mohan, 2004). Over-treatment of patients using antimicrobial regimens, specifically amoxicillin, has been known to occur in the United States and other parts of the world (Garbutt et al, 2003). In Africa and Latin America, over-treatment, over-diagnosis, and easy availability of the drug have been cited as causes of overuse. In North America, Amoxicillin continues to be overused because it is low-priced and well tolerated (Abramson & Givner, 1999). Lack of awareness and disagreeing with recommended treatment guidelines by physicians have also led to an overuse of amoxicillin in all parts of the world (Garbutt, et al, 2003).
Bacteria Resistance
Amoxicillin is recommended to treat infections arising from strains of bacteria such as E. faecalis, Streptococci, N. gonorrhoeae, V. atypical, E. coli, S. Pneumoniae, R. mucilaginosa, Staphylococcus, P. mirabilis, G. haemolysans, H. influenzae, N. gonorrhoeae, and H. Pylori (Ready et al, 2004). However, some of the bacteria have developed resistance to the drug. In the US, S. pneumoniae, the main causative agent of acute otitis media (AOM), bacterial pneumonia, and meningitis, have been found to resist amoxicillin regimen by about 21% (Abramson & Givner, 1999). H. pylori strains have developed resistance to the drug in all continents, but with varying levels of resistance depending on age, race, and health status (Dore et al, 1999). The resistance rate for H. pylori in Europe stands at 0.6% according to a recent study conducted by Koletzko et al (2006).
In Europe, particularly in Spain, H. influenza has been found to resist amoxicillin by 30.2% (Garcia-Cobos et al, 2008). In Africa, both S. pneumoniae and H. Influenzae have shown increased resistance to amoxicillin. A Study conducted in South Africa by Liebowitz et al (2003) revealed that 86% of 729 strains of S. pneumoniae were susceptible to amoxicillin. This shows 14% of the strains are resistant to the drug. Africa, Asia, and South America also suffer from amoxicillin resistant Shigella and Salmonella bacteria (Offit et al, 1999). In Africa and some parts of Asia, Shigella dysenteriae 1A, responsible for causing severe diarrhea, have resisted amoxicillin regimen by 15% and 40% respectively. E. coli and S. aureus are other common bacteria that have developed resistance to amoxicillin regimen in many parts of the world, ranging from 6% in Europe to 36% in Asia (Rahnama et al, 2009).
Resistance of the above named bacteria to amoxicillin is caused by nearly the same reasons in all the continents. Some strains of Shigella, H. pylori, E. coli, H. influenza, S. aureus and S. pneumoniae generate extended-spectrum β-lactamase enzymes, making treatment with amoxicillin difficult (Koeth et al, 2004). Resistance of these organisms, especially S. pneumoniae and H. influenza, has also been boosted by overuse and misuse of antibiotic regimens (Dagan et al, 2008). In Africa, Asia and Latin America, Shigella and E. coli’s resistance to amoxicillin regimen are also caused by despicable living conditions and lack of treatment at the opportune time (Offit et al, 1999).
Future Status on Resistance
Amoxicillin will continue to be a dominant agent against susceptible bacterial microorganisms in the future. However, the number of bacteria that is susceptible to the drug is dwindling by the day due to overuse and over-prescription (Offit et al, 1999). In Japan, a study conducted to reveal the incidence of H. pylori resistance to amoxicillin using 648 strains of the species revealed that resistance to the drug was on the increase, and could reach 35% by 2010 (Watanabe et al, 2005). In 2003, the total eradication rate of H. pylori in subjects who obtained a triple remedy containing amoxicillin stood at 81.4%. It is therefore safe to assume that the bacteria will get worse in Asia in the future. Offit et al (1999) and Rahnama et al (2009) argues that cases of E. coli, Shigella, and Salmonera will continue to worsen in the future in Africa, Asia and South America due to appalling living conditions, overcrowding and OTC antibiotic remedies, which increases resistance. A recent study conducted in Nigeria put E. coli and Salmonella spp resistance to amoxicillin at 89.1% (Oluyege et al, 2009).
According to a study conducted in Brazil by Reis et al (2002), H. influenza, the meningitis causing bacteria, is increasingly becoming resistant to many antibiotic regimens, including amoxicillin. The authors attribute this trend to irrational prescription, self prescription and easy availability of the drug. The future status for the bacteria in Latin America therefore looks grim. This is the same for H. influenza and S. pneumoniae found in Europe, North America, Africa and Asia. Garcia-Cobos et al (2008) suggest that the current treatment protocols for bacterial infections using amoxicillin in Europe and US only serve to enhance resistance due to weak policy guidelines regarding use. For him, this will negatively affect future containment of disease causing organisms, specifically H. influenza and S. pneumoniae. In the US, both organisms continue to become resistant to amoxicillin, previously considered as a drug of choice for their treatment. As such, resistance is bound to increase in the near future.
Reference List
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