4 Common Bacteria that Cause Infections in Wound Management

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Bacteria culture

by Lydia A. Meyers RN, MSN, CWCN

Wound infections are discussed in the media and are a major reason for admission into the hospital. With the importance in health care today to decrease costs, I was encouraged to do research into where infections come from and the causes for hospitalization and death among wound patients. In the current data I found there is information showing how the government has increased surveillance related to reportable admission to hospital in relation to infections in wounds by home health and hospice organizations.

Despite these efforts, infections are still a major cost burden on the health care system. According to one report, in 2005, Medicare spent $2.4 billion on wound infections, including surgical wounds and traumatic wounds. In this article, I will address the difference between a colonized wound and a contaminated wound, as well as the causes and effects of the most problematic bacteria for the health care industry: CRE, C. diff, MDRO, VRSE and MRSA.

Differences Between a Colonized Wound and Contaminated Wound

An infection can be defined in many ways, and according to Sharon Baranoski's "Wound Care Essentials", the appearance of bioburden in a wound, does not indicate infection in that wound bed. Bioburden is normal flora found on the surface of the skin and is responsible helping to keep bacteria in check. When the normal flora is taken away or decreased in number, then many different bacteria increase in pollution; and this becomes an infection. Contamination in the wound is defined as the presence of bacteria, without the multiplication of that bacteria. When the bacteria enter the wound bed from the surrounding tissue there is not automatically an infection until the numbers increase. Colonization of the wound is defined as increase in number of the bacteria. When the number and type of bacteria increase to a point that the body is no longer able to control the invasion, then symptoms of infection can be noted.

Definition of CRE

One of the bacteria of concern today is Carbapenem-resistant Enterobacteriaceae (CRE) a bacterium associated with Klebsiella species and Escherichia coli (E. coli). This bacteria has just recently been identified and is located within the digestive system. As stated by the Centers for Disease Control (CDC), "... the emergence and dissemination of Carbapenem-resistance among Enterobacteriaceae in the United States represent a serious threat to public health." The danger with this infection is the high mortality rate and its ability to spread rapidly. The CDC also reported that CRE became present and was identified in 1992 and KPC (Klebsiella pneumoniacarbapenemase) became known in 2001. Though this bacteria is not present in all areas of the country, most cases are found in health care settings. The CDC further explained that those people who are very ill and receiving treatments such as ventilators, urinary catheters, IVs, and antibiotics over long periods of time are at greater risk of developing CRE infections.

Patient Case: A patient with a surgical wound later developed an abscess infection. The culture of the abscess revealed CRE and the patient was isolated. This patient had been in the facility for many months. The patient was identified as very high risk as a result of the additional treatments being received: dependency on ventilator; a catheter for urinary retention; and plus, the patient was on long-term IV antibiotics. There was difficulty placing the patient into another facility related to the infection because of the need to continue with isolation.

Definition of Clostridium difficile

Clostridium difficile (C. diff) is a spore-forming, gram-positive bacteria that is responsible for producing toxins A and B that cause colon damage. This bacteria and the toxins it produce can cause a number of intestinal conditions including pseudomembranous colitis, toxic megacolon and perforations of the colon. Sepsis may also occur and on rare occasion, death. If toxins A and B enter the colon, they cause breakdown of the muscle and mucosa. Toxin B contributes to the major damage in the intestine.

C. diff is a common cause of antibiotic-associated diarrhea (AAD), accounting for 15-25% of all cases. There is a difference between C. diff colonization and infection as related to the signs and symptoms of the disease. A patient with symptoms of the disease considered to have the infection. According to the CDC, the symptoms include: appetite loss, nausea, watery diarrhea, fever and abdominal pain with tenderness. Patient will also test positive for the organisms or toxins in cases of C. diff infection.

Patient case: A patient had continued upper respiratory infections related to trach. The patient was transferred after a car accident to an extended care facility (to have continued physical therapy and 24-hour care by nursing), trach was finally discontinued and he was able to speak, and a decrease in infections was noted. After the last hospitalization, the patient developed diarrhea, which was diagnosed later as C. diff. All known medications were tried and the patient continued to weaken without colonization of the C. diff. This patient died within three months after the diarrhea had started.

Definition of Multiple Drug Resistant Organisms (MDRO)

MDRO stands for Multiple Drug Resistant Organisms, and according to the CDC, MDRO is defined as bacteria that are resistant to several types of antimicrobials; not just one. Commonly cited MDRO bacteria include: Escherichia coli, Klebsiella pneumoniae, Acinetobacter baumannii, Stenotrophomonas maltophilia, Burkholderia cepacia, and Ralstonia picketti.

MDRO has become prevalent in different types of health care facilities as well as different levels of care. The higher levels are in ICUs, especially tertiary care facilities, according to the CDC. When patients are located in long-term care facilities, there is an increased incidence as well as an increased mortality rate associated with MDROs. The residents that are colonized become the vehicle for the infection in acute care facilities. The CDC states there is also an increase in the number of pediatric patients infected.

Tthe key problem associated with MDRO is that colonization is common within multiple MDROs; thus, when a patient becomes colonized with VRE, MRSA, MDRO, C. diff and Candida, treating only one of the bacteria does not eliminate the others. A good program to help assure the patient progresses back to health is to focus on eliminating or reducing the risk factors. Some research suggests that a multidisciplinary approach is the best way to base a decision as to whether to use or not use antibiotics to reduce the number of patients that become colonized or contact MDRO.

Patient case: A patient in a skilled nursing facility who has been in bed for several months with a large wound caused by an insect bite, has had several surgical debridements. The patient was cultured because the wound had not shown signs of healing. The culture result showed that MDRO had become colonized within the patient, so the patient was placed in isolation for treatment in an effort to reduce the spread of the bacteria to other patients. This increased the patient's anxiety, and decreased her/his motivation to want to get out of the hospital. Approaching the treatment of the patient's infection from a holistic, multidisciplinary way may help a someone who is having issues such as anxiety as a result of treatment protocol, and may impact decisions of care.

Definition of VRE

VRE (Vancomycin-resistant Enterococci) is a bacteria that is normally located in the intestines and female genital tract. Unless a patient becomes compromised, this bacteria's presence is normal and colonization does not cause disease. There are two types (acquired and intrinsic) and two levels of vancomycin resistance known at this time: VISA and VRSA. The difference between the two levels is determined when the minimum inhibitory concentration (MIC) is available. The vancomycin MIC is 4-8µg/ml for VISA and ≥16µg/ml for VRSA.

According to the CDC, unless a person is symptomatic there is no reason to treat to treat VRE. Individuals at risk for developing a treatable VRE infection include: patients that have a lengthy history of antibiotic treatment; patients that are hospitalized; surgical patients; patients with medical devices; patients with a past history of colonized VRE; and patients with weakened immune systems.

The best steps to take in treating VRE is to remove the medical device, if possible, that is the source the infection, and provide further treatment only if there are symptoms. A treatment example is a patient who has a urinary tract infection and currently has a catheter. If there is no medical reason for the catheter, then it should be removed and the patient treated only for the length of symptom relief or if this patient becomes colonized.

Patient case: A patient who had a catheter related to a stage IV pressure ulcer showed signs of infection in the wound and urine. The patient had a fever, and the wound measurements were not changing; plus there was wound odor, increased pain with the dressing change and an increased amount of drainage. A punch biopsy of the wound bed and urinary culture was performed. The patient was positive for VRE in increased numbers, so the patient was placed in isolation and started on antibiotics. The antibiotics were stopped, another culture done, and the patient was colonized. The wound showed improved signs of healing. The patient was not removed from isolation because of the positive VRE cultures and the risk of contaminating other patients.

Definition of MRSA

Methicillin-resistant Staphylococcus aureus (MRSA) is a bacteria resistant to many of today's antibiotics. According to the CDC, 33 percent of the public has Staph in his/her nose. In fact, two in every 100 people carry MRSA. Skin infections are contracted in public areas and there is no data for the number of public cases. In the health care industry, MRSA causes life-threatening infections of the bloodstream, pneumonia, and surgical site infections.

Though MRSA is the most notorious of the infectious bacteria, it is important to note that the number of new cases has been declining since 2005. CDC data shows the number of infections has declined 54 percent from 2005 to 2011.

An example illustrating MRSA treatment is a patient that had been admitted with a severe wound and infection, and before admission was receiving antibiotic therapy. The patient was to continue antibiotic therapy after admission. The wound was not biopsied to assure that it was still infected. The patient was placed in isolation, and all visitors as well as staff, needed to be gowned and gloved to enter the patient's room. This caused the patient to become increasingly depressed and the patient wanted to leave. The patient discussions with the discharge planner and patient's family continued. Once the patient was finally able to go home, the patient's outlook improved. Supportive from the family was put into place and encouragement was provided by the health care team that the patient would do well at home.


The importance of assessing the patient for possible infection is very important to control the spread of these infections to our families, other patients and health care staff. The highest priority is using those infection prevention protocols already in place.

The limited use of antibiotics, monitoring patients at risk and limiting the use of catheters, ventilators, and IVs/PICC lines is important. Remembering that the patient is the one that is already having difficulty just being in the hospital, and to be put into isolation for the full length of time the patient is in the hospital can cause increased anxiety and depression.

The need to assess and culture each wound correctly, not just expedited quickly, is important. Knowing the history of the patient and having cultures done to assure the patient is infectious and not colonized will save money. The patient and his or her family need education on why isolation is necessary, along with information regarding the amount of time the isolation is necessary before the patient is released. The most important concern is to find ways to stop the infection quickly, not only for the patient's well-being, but also for financially sound health care delivery.

About the Author
Lydia Meyers RN, MSN, CWCN has been a certified wound care nurse for over 15 years with experience working in home healthcare, extended care facilities, hospice care, acute care, LTAC, and wound clinics. Her nursing philosophy to "heal wounds as quickly as possible" is the guiding force behind her educational pursuits, both as a teacher and a student.

The views and opinions expressed in this blog are solely those of the author, and do not represent the views of WoundSource, Kestrel Health Information, Inc., its affiliates, or subsidiary companies.

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