Mediastinitis And The Germ Theory Nursing Essay

Prevention and treatment of infection is a large part of practice after surgery. This paper will examine current practice in preventing and treating sternal wound infections, or mediastinitis, after surgery and examine the germ theory and look at how, when applied to practice, it can help decrease sternal wound infections. Sternal wound infections are defined by involving sternal muscle, bone, or mediastinum (Killiam, Russel, & Keister, 2009). Mediastinitis occurs in 5% of patients who have undergone a sternotomy, a procedure done primarily for cardiac procedures (Bosen & Mackavich, 2006). Complications of mediastinitis could be “osteomyelitis, sternal dehiscence, sepsis, or right ventricular rupture (Bosen & Mackavich, 2006, p. 64cc1).” Out of the 5% of patients who end up with mediastinitis, up to 47% die (Bosen & Mackavich, 2006). Treatment of mediastinitis could be as simple as debridement of the wound and antibiotic therapy or as involved as debridement with the wound left open, continued wet to dry dressing changes and sternum removal with following muscle flap coverage of the wound. A new method of treatment involves negative pressure with placement of a wound vac (Bosen & Mackavich, 2006).

Risk Factors

In a study performed in Australia by Robinson, Billah, Leder, and Reid (2007) found that preoperative risk factors for deep sternal wound infections (DSWI) included “diabetes preoperative dialysis, respiratory disease, body mass index, and angina CCS Class 3 or 4. The intra-operative factors were use of a ventricular assist device (VAD), cardiac transplantation, and a procedure involving the use of both internal thoracic arteries (ITAs) (Robinson, Billah, Leder, & Reid, 2007, p. 168).” Valve procedures carried a higher risk of DSWI with the most frequent risk factors were diabetes (49.67% of DSWI patients), being overweight (83.01% of patients) and both ITAs used (17.65% of patients) (Robinson et al., 2007). Diabetic patients are two to five times more likely to develop DSWI, however diagnosis alone was not the only factor, a hyperglycemic state is needed before, during, and after surgery (Killiam et al., 2009).

Current Research

While there is a lot of current research available, it is limited in its scope. There is a lot of research on risk factor reduction, especially focusing on hyperglycemia. There is a lot of research offered on how tight glucose control will help decrease the chance of infection status post cardiac surgery. Another area in which a lot of current research is available is the treatment of mediastinitis with wound vac, or negative pressure therapy. A flaw with the existing research is the inability to study this problem in a randomized manner. As with many medical diagnoses a researcher must first wait for the patient to develop the problem, in this case a person must first need surgery and then go onto develop a sternal wound infection. Also,

Germ Theory

The theory selected to apply to this problem is the germ theory. This was chosen due to its attempts to explain how infection occurs. The germ theory of disease is often viewed as the “single most important contribution to medical science and practice (Abedon, 1998). Louis Pastuer proposed the germ theory based “on the effects that microorganisms had on fermentation and putrefaction of organic matter (Toledo-Pereyra, 2009, p. 82).” Pasteur first made discoveries with bacteria in the germ theory of fermentation and later transferred the same process to disease with the germ theory of disease (Toledo-Pereyra, 2009). First proposed in 1858, this theory is still relevant to practice today. Germ theory is the theory that a specific ‘germ’ is capable of causing an infective process. Facets of this theory are used to prevent infection in current practice by practicing hand washing, cleansing a wound and using antibiotic ointment, or treating a surgery patient with prophylactic antibiotics (McEwen & Wills, 2007). It also is used to identify, understand, and manage infections disease by helping to identify the contributory agent and then preventing and treating the disease (McEwen & Wills, 2007).

The germ theory is often used in nursing research, often without thought because it is now thought to be very basic science, but was originally borrowed from the biomedical sciences. This theory has its basis in middle range theory. Middle range theories can be “(1) a description of a particular phenomenon, (2) an explanation of the relationship between phenomena, or (3) a prediction of the effects of one phenomenon or another (McEwen & Wills, 2007, p. 38).” The germ theory attempts to describe the phenomena of infection by stating it is caused by germs. Strengths of this theory include many viewings of various microorganisms or ‘germs’ and multiple research studies that have shown this theory to be true. The major limitation of this theory is its simplicity. While infection is a basic concept with an agent being introduced and causing infection there are many aspects that are not accounted for in the theory such as strength of a patient’s immune system, nutrition status, and patient’s overall health status (obesity, smoking, other chronic diseases).

Application of the Germ Theory

To use the germ theory to decrease sternal wound infections would be a simple process of keeping germs away from the surgical incision. If no germs or various microorganisms were introduced into the incision from the point of surgery to healing, infection would not occur. The most basic application of the germ theory in attempts to stop sternal wound infections is the act of hand washing (Dunaway & Goldrick, 2007). If all surgeons, nurses, techs, and anyone else present in the operating room and those around during the recovery period would simply take the time to wash their hands thoroughly introduction of bacteria and microorganisms not a part of normal flora for that patient would decrease dramatically and lessen the chances of an infection.

Also important is managing aseptic technique throughout the patient’s stay. To do this have patients bathe with antiseptic skin prep, check for sterility in instruments and packing in the operating room, maintain sterility in the operating room, maintaining sterile procedure when dressing the incision, not changing the dressing for 24-48 hours, and using sterile procedures if the dressing must be changed (Dunaway & Goldrick, 2007). These are all examples of ways to decrease chances of the introduction of a ‘germ’ into the incision site and help decrease chances of infection.


It is always important, as any person in the medical field to be aware of the ideas behind the germ theory, any infection for any patient can be potentially dangerous. It is especially important in the cardiac surgery field with a 47% chance of mortality with a case of sternal wound infection. While there are many risk factors, modifiable and non-modifiable, involved in preventing postoperative sternal wound infections, but sometimes the simplest concepts can be the most important. While the germ theory was first proposed a century and a half ago, it is still relevant and practical to modern medicine and nursing practice.