Antibiotic-Resistant Infections, MRSA, and C-Diff

Janet Pheonix, MD, MPH, Rachel Hampton, B.A. and Sarah Miller, R.N.

Updated August 2010

There is growing concern about the presence of Methicillin-resistant Staphylococcus Aureus (MRSA), a type of bacteria that is resistant to most antibiotics.  These bacteria used to be found mainly in medical facilities and nursing homes, but in recent years they have also been found in gyms, schools, sports clubs, and other places where people are in close contact. MRSA can spread easily in these environments through physical contact or sharing athletic clothing or equipment. The spread of MRSA threatens public health because the bacteria are resistant to most antibiotics and very difficult to treat.

What is Staphylococcus aureus (staph)?

Staphylococcus aureus, commonly referred to as “staph,” are bacteria frequently found on the nose or skin. Approximately 20-30% of people carry staph but are not infected (CDC, 2007). Staph bacteria are the most common causes of skin infections such as pimples and boils in the United States. They are usually harmless, but if the organisms enter the bloodstream through a cut or wound, they can cause an infection that can spread throughout the body.  These serious infections include pneumonia, septicemia (a bloodstream infection) and surgical wound infections.

What is MRSA?

Methicillin-resistant Staphylococcus aureus (MRSA) is one type of staph aureus that has developed resistance to a family of antibiotics similar to penicillin.  The growing number of antibiotic-resistant bacteria poses a very serious threat to public health. In 1974, MRSA infections accounted for 2% of the total number of staph infections; in 1995 it was 22%; in 2004 it was 63%. (CDC, 2007 Although MRSA is resistant to many antibiotics, a handful of drugs can still be used to treat the infection. According to a  report published in the Journal of the American Medical Association, about 94,000 people were infected with MRSA in 2005, and approximately 19,000 people died during a hospital stay related to the infection (Klevens et al., 2007).  The U.S. Center for Disease Control and Prevention estimates that 1% of the population carries MRSA (CDC, 2007).

What Causes Antibiotic Resistance?

Since the discovery of penicillin in 1928, antibiotics and antimicrobial drugs have been widely used in the United States. Over time, some bacteria have developed ways to survive these drugs. Unfortunately, the widespread use of antibiotics has contributed to the development of antibiotic-resistant bacteria.

When a person takes an antibiotic, the drug kills many bacteria, but a few will survive. These surviving bacteria are resistant to that antibiotic. They then multiply. This means that every time a patient takes an antibiotic, he or she is creating more drug-resistant bacteria. Although bacterial antibiotic resistance is an evolutionary process, societal factors also contribute to the problem. The inappropriate use of antibiotics (such as using them to treat viral infections like colds) contributes to the growing number of antibiotic-resistant bacteria today. For years, antibiotics have been prescribed for colds, earaches, flu, and other infections that normally clear up on their own. Inappropriate use of antibiotics, such as not taking doses as prescribed, can also contribute to the emergence of antibiotic-resistant bacteria.

In recent years antibacterial household products have become popular, and this trend also contributes to the increasing number of antibiotic-resistant bacteria. Antibacterial agents are commonly found in cleaners, soaps, detergents, hand lotions, tooth brushes, and sometimes even plastic containers and mattresses. Although people buy these products with the intent of protecting their family from harmful germs, the widespread use of antibacterial products helps to produce resistant bacteria.

Another cause for concern is the use of antibiotics in livestock (Mayo Clinic, 2007). Cows, chickens, and pigs are often fed low levels of antibiotics over long periods of time, and this is believed to promote the survival of antibacterial-resistant bacteria in livestock. There is some concern that these resistant bacteria can be transferred to humans through direct contact with animals or the consumption of their meat.

What Causes Infection?

Hospital- and Healthcare-acquired MRSA occurs as a result of exposure during medical care, usually after surgery or a procedure involving the insertion of foreign material into the body.  The staph or MRSA bacteria can enter the body through a cut, wound, or abrasion. An infection may result. Staph organisms are carried from person to person through human hands, especially in a healthcare environment.

Community-acquired MRSA is caused by contact with people who are infected with MRSA or objects that infected people have been in contact with. This includes things like gym equipment and personal items like towels, razors, and clothing. If the bacteria gets into an opening in your skin (even a tiny one that you can’t see), it can cause an infection.

What are the Symptoms?

Staph infections, including MRSA, normally start as small bumps that resemble pimples or boils, and can be red, swollen, painful, or have pus or other drainage. Sometimes the infection is limited to the skin, but the bacteria can also burrow down into the body, and cause infections in the bones, joints, surgical wounds, the bloodstream, lungs, and heart valves. Symptoms of a more serious infection  could include fever, difficulty breathing, sweating, pallor, and rapid heart rate. If the valves of the heart are infected, symptoms may include chest pain or irregular heart beats. In some cases, excessive bleeding may occur.

Are Some People More Likely to Get an Infection?

A study of MRSA infections in nine metropolitan areas of the United States found that about 80% of MRSA infections occur as a result of health care interventions. (Kallen et.al., 2010). For example, people often get urinary tract infections when MRSA gets into their urinary catheters or they will get septicemia (blood infection) when MRSA gets into their IV lines. People who have been hospitalized for a significant period of time are likely to be at greater risk (Klevens et al., 2007). Living in unsanitary or overcrowded conditions also increases the risk of MRSA, and outbreaks have occurred in military training facilities and prisons (Mayo Clinic, 2007).

There is now concern about the risk of infection in schools. Infections can spread from person to person in gyms and locker rooms through shared personal items like towels, razors, and athletic gear. Bacteria can also enter the body easily through cuts and abrasions during team practice or sports. However, as long as a person doesn’t wear another person’s personal items and washes his or her own frequently, the school environment is not likely to play a significant role in the transmission of MRSA.

How Can I Prevent Infection?

The best way to prevent staph or MRSA infections is to practice good hygiene.

  • Keep your hands clean by washing regularly with soap and water or using an alcohol-based hand sanitizer.
  • Limit your use of antibacterial products in your home. Instead of using antibacterial cleaners, use an alcohol-based cleaner. Use soap instead of antibacterial hand wash.
  • Keep cuts and wounds covered with a bandage until they are completely healed.
  • Avoid contact with other people’s wounds or bandages.
  • Avoid sharing personal items such as towels, sheets, razors, clothing, and athletic equipment.
  • Washing clothing and linens regularly with hot water and dry them in a hot dryer; wash athletic clothing after every use.
  • Non-washable athletic equipment (e.g. head gear) should be wiped down with a phenol- or chlorine-based wipe such as liquid Lysol after each use.
  • Avoid sharing lip balms, lotions, or any other cosmetics.
  • Eat organic meat, which comes from livestock that have not ingested antibiotics

Treatment

Although MSRA is resistant to most drugs, it can still respond to certain medications. Most doctors rely on intravenous vancomycin or other antibiotic drugs in its class (glycopeptide antibiotics) to treat resistant germs such as MRSA. Many less severe staph skin infections can be treated by draining any abscesses or boils. This should only be done by a healthcare professional.

Concerns for the Future

Despite serious concerns about the dramatic increase in MRSA in recent years, many antibacterial-resistant bacteria, such as MRSA, can still be treated with antibiotics.

Although not a new antibiotic, vancomycin has never been widely used because it usually must be given intravenously to be effective, and it has more side effects than many other antibiotics. Because of it’s effectiveness for MRSA, it has become the antibiotic of last resort, and is used to treat only the most serious, life-threatening infections. It should not be used unless other antibiotics have failed; otherwise, more bacteria will become resistant to vancomycin as well. In 2002, the CDC reported the first case of staph aureus infections resistant to vancomycin (NIAID, 2006). Since then, several more cases of vancomycin-resistant bacteria (VRSA) have been reported.

There is also a bacteria called VRE (Vancomycin-resistant enterococcus), which is not staph but is resistant to Vancomycin as well. Increased use of Vancomycin has caused an increase in VRE infections.

C-Diff

C-diff (Clostridium Difficile) is a different type of bacteria that is resistant to some antibiotics as well as alcohol-based hand sanitizers. It is normally present in our digestive tracts, but is kept in check by other normally-occurring bacteria. Sometimes, when people take antibiotics, they lose some of the bacteria that keep C-diff under control. When this happens, the number of c-diff bacteria grow and cause an infection, the main symptom of which is very severe diarrhea. People can also catch c-diff from hospital surfaces and the hands of health care providers, especially if the providers are using hand sanitizer instead of soap and water. There have also been cases of people catching c-diff in the community, probably from touching contaminated surfaces and then their mouths (Weber et. al., 2010, Naggie et.al., 2010). Right now, there are several antibiotics that are effective against c-diff, but it is important to take steps to prevent its transmission, such as using antibiotics only when they are absolutely needed, proper cleaning in hospitals, hand washing with soap and water for health care professionals, and hand washing after using the bathroom and before eating for everyone.

Although new antibiotics are being developed, there is currently no effective treatment for VRSA or VRE. As we continue to use antibiotics, we will probably to continue to see more antibiotic-resistant infections.  It is important that the spread of antibiotic-resistant bacteria is halted, before even the drugs reserved for resistant infections become ineffective.

References

Kallen, A.J., Mu, Y., Bulens, S., Reginold, A., Petit, S., Gershman, K., et.al. (2010) Health care-associated invasive MRSA, 2005-2008. JAMA, 304(6) pp. 641-8.

Klevens, R. M., Morrison, M. A., Nadle, J., et al. (2007). Invasive methicillin-resistant staphylococcus aureus infections in the United States. Journal of the American Medical Association, 298(15):1763-1771.

Naggie S, Frederick J, Pien BC, Miller BA, Provenzale DT, Goldberg KC, Woods CW. Community-associated Clostridium difficile infection: experience of a veteran affairs medical center in southeastern USA. Infection. 38(4):297-300.

Weber DJ, Rutala WA, Miller MB, Huslage K, Sickbert-Bennett E. (2010) Role of hospital surfaces in the transmission of emerging health care-associated pathogens: norovirus, Clostridium difficile, and Acinetobacter species. Am J Infect Control. 38(5 Suppl 1):S25-33

Centers for Disease Control and Prevention, (2005). Community-associated MRSA information for the public. Retrieved October 31, 2007 from the World Wide Web: http://www.cdc.gov/ncidod/dhqp/ar_mrsa_ca_public.html.

Center for Disease Control and Prevention, (2007). MRSA in Health Care Settings. Retrieved October 31, 2007 from the World Wide Web: http://www.cdc.gov/ncidod/dhqp/ar_mrsa_spotlight_2006.html.

Mayo Clinic, (2007). MRSA infection. Mayo Foundation for Medical Education and Research (MFMER). Retrieved October 31, 2007 from the World Wide Web: http://www.mayoclinic.com/health/mrsa/DS00735.

National Institute of Allergy and Infectious Diseases (NIAID), (2006). The Problem of Antimicrobial Resistance. Retrieved November 11, 2007 from the World Wide Web: http://www.niaid.nih.gov/factsheets/antimicro.htm