salmonella.bmpAccording to press reports, state health officials are investigating a salmonella death in Ardmore, Oklahoma. 72-year-old Dewey Teeg died recently of salmonella poisoning, according to the reports.  Officials would not confirm where Teeg was infected, but say its an ongoing investigation.

Elderly people sometimes suffer devastating illnesses in situations where otherwise health adults would not.  Here are a few reasons why:

1. Aging of the Gastrointestinal Tract—An Invitation to Infection

Inflammation and shrinkage of the gastric mucosa increase with age. These changes lead to low gastric acidity. In patients with gastric ulcer disease, the drugs used to treat the condition further block gastric acid production. Because stomach acids play an important role in limiting the number of bacteria that enter the small intestine, low gastric acidity increases the likelihood of infection if a pathogen is ingested with food or water.

Gastrointestinal mobility (peristalsis) decreases with age. Peristalsis, which is the mechanism that propels the stomach contents through the intestinal tract, is also the mechanical means for removing ingested, life-threatening pathogens. The risk of infection by potentially invasive pathogens corresponds with the duration of contact between the pathogen and the intestinal mucosa. Thus, a decrease in peristalsis delays the clearance of the pathogen from the intestinal tract and contributes substantially to the increased prevalence and severity of infection in the elderly.

2. A Higher Prevalence of Underlying Medical Conditions

Underlying medical conditions or disease (co-morbid factors) also contribute to the morbidity and mortality of infection in the elderly. Among hospitalized patients, those older than 65 develop pneumonia twice as often as younger patients due to poor nutrition, neuromuscular disease (poor cough reflex and aspiration), pharyngeal colonization, depressed level of alertness, endotracheal intubation, intensive care unit admission, nasogastric tube use, and antacid use. Pneumonia is the leading infectious cause of death in the elderly.

Atherosclerosis, another common co-morbid disease, compromises circulation and blood flow to the peripheral tissues and the skin, particularly in elderly individuals who are hospitalized and bedridden with an infectious illness. Unfortunately, it is the skin and the previously discussed mucous membranes that serve as the body’s first line of defense against invasion by infectious microorganisms. Loss of the integrity of the skin may result in the development of pressure ulcers, which are warm, moist mediums for infectious microorganisms to rapidly multiply and are associated with a number of infectious complications.

When an infectious microorganism, regardless of source, gains access to the bloodstream, the patient may develop systemic sepsis, also know as bacteremia. Bacteremia is most common in people who are already affected by, or are being treated for, some other medical problem (co-morbid disease); conversely, people in good health with strong immune systems rarely develop bacteremia. The main sources of bacteremia in elderly patients are the urinary tract, gastrointestinal tract, respiratory tract, and the skin. Other potential sources include surgical wounds, invasive tubes and catheters, intravenous lines—virtually any site where an invasive medical procedure has occurred. Bacterial organisms most likely to cause bacteremia include members of the Staphylococcus, Streptococcus, and Escherichia coli genera. Because bacteremia is far more prevalent in those with co-morbid conditions, which group is substantially populated by the elderly, the presence of co-morbid conditions is clearly a determinant of the mortality associated with infectious disease.

3. A Weakened Immune System—the Inability to Fight Off Infection

With advancing age come progressive weakness, decline, and dysfunction of the immune system. Many of the body’s natural physiologic responses to infection are therefore blunted in the elderly; and the intensity of many clinical signs and symptoms in an elderly patient with an infectious process are muted when compared to those in a younger person. This age-related decline contributes significantly to the increased risk of severe illness and mortality in elderly persons with infectious disease.

The effect of a weakened immune response on the health of an elderly person often manifests most apparently during periods of intense stress (e.g., surgery, sepsis, multiple organ failure, malnutrition, dehydration).