Postoperative Nosocomial Infections

Surgical patients are prone to develop a wide variety of nosocomial infections during the postoperative period, which include SSIs, UTIs, pneumonia, and bacteremic episodes. SSIs are discussed above, and the latter

types of nosocomial infections are related to prolonged use of indwelling

tubes and catheters for the purpose of urinary drainage, ventilation, and

venous and arterial access, respectively.

The presence of a postoperative UTI should be considered based on urinalysis demonstrating WBCs or bacteria, a positive test for leukocyte esterase, or a

combination of these elements. The diagnosis is established after greater than

104 CFU/mL of microbes are identified by culture techniques in symptomatic

patients, or greater than 105 CFU/mL in asymptomatic individuals. Treatment

with a single antibiotic that achieves high levels in the urine is appropriate.

Postoperative surgical patients should have indwelling urinary catheters removed as quickly as possible, typically within 1–2 days, as long as they are

mobile.

Prolonged mechanical ventilation is associated with an increased incidence

of pneumonia, and is frequently because of pathogens common in the nosocomial environment. Frequently these organisms are highly resistant to many

different agents. The diagnosis is established based on clinical criteria of purulent sputum, fever, elevated WBC, and roentgenographic evidence of one

or more areas of pulmonary consolidation. Consideration should be given to

performing bronchoalveolar lavage to obtain samples to assess by Gram stain

and to performing a culture to assess for the presence of microbes. Surgical

patients should be weaned from mechanical ventilation as soon as feasible to

reduce the incidence of this complication.

Infection associated with indwelling intravascular catheters has become a

common problem among hospitalized patients. Because of the complexity of

many surgical procedures, these devices are increasingly used for physiologic

monitoring, vascular access, drug delivery, and parenteral nutrition. Among

the several million catheters inserted each year in the United States, approximately 25 percent will become colonized, and approximately 5 percent will be

associated with bacteremia. Many patients who develop intravascular catheter

infections are asymptomatic, often exhibiting an elevation in the WBC count.

Blood cultures obtained from a peripheral site and drawn through the catheter

that reveal the presence of the same organism increase the index of suspicion

for the presence of a catheter infection. Obvious purulence at the exit site

of the skin tunnel, severe sepsis syndrome because of any type of organism

when other potential causes have been excluded, or bacteremia because of

gram-negative aerobes or fungi should lead to catheter removal.