Gram-negative organisms may be identified by using the Gram stain procedure.

Examined under the microscope, these organisms retain the pink or red counterstain, safranin. Four species of bacteria most frequently cause gram-negative infections: Escherichia coli, Enterobacter, Klebsiella pneumoniae aeruginosa, and Proteus.

Gram negative bacteria invade the bodies of individuals that are not in the best of health. Persons in good health are not usually bothered by gram-negative infections.

a. Infection Development.

Gram-negative infections develop in various parts
of the body and have a variety of causes.

(1) On the skin, these infections are a form of leukemia and must be treated with chemotherapeutic agents.

(2) In the respiratory tract, these infections develop from aspiration, tracheostomy, and mechanical ventilation.

(3) In the vascular system, gram-negative infections develop from intravenous catheters, intracardiac pacemakers, venous cutdowns, pressure-monitoring devices, total parenteral nutrition, and surgical procedures.

(4) In the gastrointestinal tract, infections develop from obstruction, perforation, abscesses, and diverticuli.

(5) In the genitourinary tract, infections come from indwelling catheters, and urinary obstruction.

(6) In the reproductive system, gram-negative infections develop from abortion, and postpartum (after childbirth) period.

b. Signs/Symptoms.

During the early stage, the skin is warm and dry. The patient may experience a shaking chill, and his temperature may rise rapidly. The patient’s personality may change; his behavior may not be appropriate. Low blood pressure may be indicated by cool, clammy skin, tachycardia/tachypnea, proceeding to peripheral cyanosis, oliguria, and death as a result of vascular collapse.

c. Treatment.

First, identify the source of infection. Collect blood cultures and
obtain other smears and cultures as indicated. When possible, remove any source of possible infection such as venous or urinary catheters. Incise and drain any local infections. Prevent and treat shock by monitoring vital signs, administering IV fluids and blood, administering oxygen, and administering antibiotics.