Association Between Body Mass Index and Risk for Infection

Obesity

(Adobe Stock, unknown)

For patients with an adult body mass index of 30.0 or higher, studies have depicted an increased risk of infections in both genders. Infections studied included postoperative infections, pneumonia, skin infections, and other nosocomial infections. Obesity influences the immune response, which can lead to susceptibility to infections. Excess adipose tissue causes pro-inflammatory pathways to be activated and can lead to chronic low-grade inflammation. Dietary intervention and regular exercise have been proven to reduce low-grade inflammation in obese patients. Inflammation helps to maintain homeostasis in the body, and obesity can be linked to a shift in the frequency of cells such as macrophages. Obesity has also been associated with changes in neutrophil, monocyte, lymphocytes, and lower T-cell and B-cell-induced proliferation. With this in mind, should physicians have best practices related to infection prevention in patients who are obese or morbidly obese?

Body mass index (BMI) data is recorded in patients undergoing surgical procedures and is reported to the National Healthcare Safety Network (NHSN) or other surveillance networks in other countries. Obesity is on the list as a risk for surgical site infections (SSI), and guidelines recommend using increased doses of prophylactic antimicrobials for patients that are morbidly obese. A study conducted reviewing data from a Dutch surveillance network concluded that obese and morbidly obese patients had at least a 1.3 increased risk of SSI compared to underweight and normal-weight patients. This increase in the risk of SSI in obese patients is multifactorial. It can be attributed to differences in the tissue oxygenation of obese patients- obese surgical patients have been shown to have reduced tissue oxygenation and wound hypoxia, which slow the healing process. Immune cells also require high oxygen demands. All patients should monitor their incision sites after surgery, ensure it remains clean, and have the appropriate dressing if necessary. Patients should notify their physician of any concerning changes in their incision sites, such as redness or pus, which could be signs of infections.

Antibiotic drug dosing in obese patients is important, and patients can be given the incorrect dose. Incorrect dosing can lead to treatment failure in patients with infections such as pneumonia. Recognizing obesity-related pharmacokinetic and pharmacodynamic alterations is important in treating patients and can prevent underdosing or overdosing. Overdosing may lead to toxicity risk. A study on underdosing common antibiotics in the emergency department found that physicians frequently underdosed cefepime, cefazolin, and ciprofloxacin in obese patients. This underdosing can lead to treatment failure and antibiotic resistance.

Patients with obesity are at a higher risk of skin infections as a result of obesity and comorbidities such as diabetes and impaired circulation. Some of these bacterial and yeast skin infections include candidiasis- care teams should promote reducing moisture, body heat, and sweating to lessen the risk of infection. Ensure that patients have good personal hygiene habits, especially while inpatients, and that their bed sheets and hospital gowns are changed regularly and as needed. Turning patients at reoccurring intervals is also beneficial in promoting good skin hygiene.

Other nosocomial infections associated with obesity include pneumonia, catheter-associated bloodstream infections, Clostridium difficile, urinary tract infections, and periodontitis.

However, data on the incidence and outcome of specific infections in patients with a BMI of 30.0 or higher is still limited, and more research is necessary to understand the patient’s pathophysiology.