Superbugs : A Primer

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Superbugs
Superbugs

The introduction of antibiotics into modern healthcare has added years onto the average lifespan of humans in developed countries. However, the widespread use and misuse of antibiotics has led to the current problem of antibiotic resistance. Multiple antibiotic resistant strains of some bacteria have reached a stage where virtually no antibiotics are available for treatment.

widespread use and misuse of antibiotics has led to the current problem of antibiotic resistance

The development of resistance is a natural process for all types of antibiotics. The way antibiotic resistance arises, in simplistic terms, is that antibiotics kill the vulnerable pathogens (the ones that are making you sick) and leave behind the stronger bacteria. The stronger bacteria, because they were not killed by the antibiotic, slowly accumulates resistance to the antibiotic used. The typical rates of resistance development to a new drug is about 1%. However, due to improper use of antibiotics (i.e., incorrect dosing, poor quality product, prescribing antibiotics for non-bacterial infections, etc.), the rate of resistance has increased dramatically. This has caused a massive surge in the number of resistant bacteria. These drug resistant bacteria are sometimes referred to as superbugs. The following are some of the most significant superbugs that are becoming more and more resistant to traditional antibiotics:

Tuberculosis

Tuberculosis is an infectious disease caused by the bacterium, Mycobacterium tuberculosis that attacks the lungs. It is the second largest single infectious cause of death globally, accounting for the deaths of 2% of the world population annually. Standard anti-TB drugs, including rifampicin, isoniazid, pyrazinamide and ethambutol, have been used for decades to manage the disease. Due largely to inadequate treatment in developing countries, the emergence of multidrug-resistant TB (MDR-TB) and extensively drug-resistant TB (XDR-TB) has become a global concern. The resistance in MDR-TB is typically to rifampicin and isoniazid, which are considered to be first-line TB drugs. With XDR-TB, the bacteria also has resistance to three or more of the six classes of second-line drugs. Totally drug resistant TB (resistant to all known drugs) has also been observed in some countries.

Pneumonia

Pneumonia is an inflammatory disease of the lung which causes difficulty breathing, cough, chest pain and fever. Pneumonia can be viral or bacterial, the latter of which is treated with a course of antibiotics. Some bacteria, including Streptococcus pneumoniae have become resistant to one or more first-line antibiotics, leading to treatment failures. Most commonly the resistance is to penicillin, but may also include other antibiotics, including Erythromycin, Trimethoprim, Vancomycin, Chloramphenicol, Ofloxacin and Tetracycline. Drug resistant Streptococcus pneumoniae (DRSP) outbreaks have been reported in child care centres, nursing homes and institutions for those with HIV. There is a vaccine available to prevent DSRP, which is recommended for high-risk children and older adults.

Gonorrhea

Gonorrhea is a sexually transmitted infection (STI) that has become a major public health issue. Resistance to most first-line antibiotics is prevalent among most strains, so treatment today is typically with the drug ceftriaxone, in combination with azithromycin or doxycycline. However, some strains of gonorrhea are now showing resistance to this regimen, which will make the infection increasingly difficult to treat.

CRE

Carbapenem-resistant Enterobacteriaceae (CRE) is a naturally-occurring bacterium found in human intestines. These bacteria don’t cause any problems unless they are somehow transmitted to the blood or other organs, where they can cause serious infections or death. Transmission is person to person, usually through direct contact with infected fecal matter, medical instruments or skin. Carbapenems are very strong antibiotics that are used to treat illnesses caused by multidrug-resistant bacteria, and are typically only prescribed in very serious cases. Bacteria that resist carbapenems have very few treatment options. The death rate for CRE bacteria that reach the bloodstream can range from 40-50%.

MRSA

Methicillin-resistant Staphylococcus aureus (MRSA) has been an issue in healthcare settings for decades. MRSA is an infection caused by a type of staph bacteria that has become resistant to the antibiotic treatments normally prescribed for staph infections (e.g. methicillin). MRSA infections manifest on the skin and their drug resistance make them difficult to treat. MRSA is a leading cause of hospital acquired infections (HAI), typically transmitted through invasive procedures, like surgeries; and are sometimes community associated, typically transmitted through skin to skin contact, like in contact sports, daycare centres and in crowded living conditions.

VRE

Vancomycin Resistant Enterococcus (VRE) is bacterium that exists in the bowel of every human. Healthy people carry VRE with no signs or symptoms, but in sick and immune-compromised patients, VRE can cause infections in the bloodstream (sepsis), as well as meningitis and pneumonia, among many others. Vancomycin is a first line antibiotic indicated for bloodstream infections, so a bacteria that has developed resistance to this drug is difficult to treat.

Conclusion:

As more and more superbugs emerge, it will be imperative that research into the development of new antimicrobials be funded and supported. Infection prevention through better hygiene, vaccinations and better access to healthcare will also be key components to mitigating antibiotic use. Precautions in antibiotic use should be at the forefront of everyone’s mindset.

References:

Antibiotic-resistant illnesses and bacteria. (2014, October 24). Retrieved from http://healthycanadians.gc.ca/drugs-products-medicaments-produits/buying-using-achat-utilisation/antibiotic-resistance-antibiotique/illnesses-maladies-eng.php

CRE Bacteria Infection (Carbapenem-Resistant Enterobacteriaceae). (2015, February 24). Retrieved from http://www.medicinenet.com/cre_infection/article.htm

Drug Resistant Streptococcus pneumoniae (DRSP). Retrieved from http://southernnevadahealthdistrict.org/health-topics/drsp.php

Centre for Disease Control, Drug Resistant TB. (2015, October 15). Retrieved from http://www.cdc.gov/tb/topic/drtb/

Groopman, Jerome (2012, October 1). Sex and the Superbug. [Article in The New Yorker]. Retrieved from http://www.newyorker.com/magazine/2012/10/01/sex-and-the-superbug

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Harris, Anthony. Retrieved from http://www.uptodate.com/contents/methicillin-resistant-staphylococcus-aureus-mrsa-beyond-the-basics

Kielstra, Paul (2014, June 30). Ancient enemy, modern imperative: A time for great action against tuberculosis. Retrieved from http://www.economistinsights.com/healthcare/analysis/ancient-enemy-modern-imperative

Mayo Clinic (2014, January 2). Legionnaires’ disease. Retrieved from http://www.mayoclinic.org/diseases-conditions/legionnaires-disease/basics/causes/con-20028867

Omerod, L.P (2005, May 11). Multidrug-resistant tuberculosis (MDR-TB): epidemiology, prevention and treatment. Retrieved from http://healthycanadians.gc.ca/drugs-products-medicaments-produits/buying-using-achat-utilisation/antibiotic-resistance-antibiotique/illnesses-maladies-eng.php

Pneumococcal Disease (2015, June 10). Retrieved from http://www.cdc.gov/pneumococcal/drug-resistance.html

Quinte Health Care (2015, April) Clostridium Difficile. Retrieved from http://www.qhc.on.ca/clostridium-difficile-p144.php

Vancomycin Resistant Enterococcus (VRE)
http://www.health.nt.gov.au/Vancomycin_Resistant_Enterococcus_VRE/index.aspx

Todar, Kenneth. Bacterial resistance to Antibiotics. Retrieved from http://textbookofbacteriology.net/resantimicrobial.html

World Health Organization (2012). Global action plan to control the spread and impact of antimicrobial resistance in Neisseria gonorrhoeae.

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