Risk Factors Affecting the Incidence of Infection after Orthopaedic Surgery: The Role of Chemoprophylaxis

Article excerpt

SUMMARY

The incidence of surgical site infection and urinary tract infection following orthopaedic procedures has diminished in recent years due to modern antimicrobial prophylaxis.

We conducted a case-control study (100 cases, 100 controls) in order to evaluate the risk factors associated with infection after orthopaedic procedures. The following risk factors were defined: gender, age, comorbidities [rheumatoid arthritis, diabetes mellitus, obesity (>30 kg/m^sup 2^), peripheral vessel disease], pre- and post-operative glucose levels, pre-operative and post-operative length of stay (days), duration (days) of urinary catheterization, type of parenteral antibiotic prophylaxis (cefotaxime or vancomycin), time of surgery (elective or scheduled), American Society of Anesthesiologists (ASA) Score (0-3), type of surgery (fracture osteosynthesis, joint replacement, spinal surgery, other), and the type of anesthesia administered (general, epidural, spinal).

Urinary tract infection was the most frequent post-surgical infection (71 out of 100 cases) followed by surgical site infection (15 out of 100 cases). Using the multivariable logistic regression model, we found out that only the type of chemoprophylaxis was statistically significant risk factor (p<0.001) associated with post-surgical infection. More specifically, the use of vancomycin instead of cephalosporin is associated with a lower risk of infection.

Key words: infection, post-surgical, orthopaedic, risk factors

INTRODUCTION

The incidence of deep and superficial surgical site infection (SSI) and urinary tract infection (UTI) following orthopaedic procedures has extremely decreased during recent decades due to modern antibiotic prophylaxis. Surgical site infection is the most serious complication occurring in 1% to 3% of orthopaedic surgical procedures (1). Most of these infections are the result of direct or airborne contamination at the time of surgery although approximately one-third of infections follow hematogenous seeding of the joint. Urinary tract infection is the second most common hospital-acquired infection reaching incidence of 25-28%. Mortality is tripled in patients having UTI and there is evidence of increased risk for metastatic infection around joint replacements although the latter finding remains controversial (2).

Risk factors associated with SSI include obesity, diabetes mellitus, rheumatoid arthritis, increased American Society of Anesthesiologists (ASA) risk index score (3), whereas female sex, number of days of urinary catheterization, and inappropriate catheter management seem to affect the risk of UTI (2).

In order to elucidate further the aetiology of any kind of infection inpatients undergoing orthopaedic procedures, we conducted an observational study using a case-control design.

MATERIALS AND METHODS

A case-control study was performed in a tertiary care university teaching hospital aiming at the identification of risk factors for infection developing after an orthopaedic procedure. The study was approved by the institutional ethics committee.

The study group consisted of patients who experienced an infection following orthopaedic surgery while controls were randomly selected among patients who had undergone orthopaedic surgery without a subsequent infection. The definitions of infections investigated are given below: A superficial surgical site infection had a discharge, which yielded organisms from the culture of aseptically aspirated fluid or tissue from a swab; Deep infection was considered in case of strong clinical and radiological evidence of infection such as periosteal elevation, focal osteolysis, hot and swollen joint, draining sinus and/or positive intraoperative culture; A urinary tract infection was defined as urine culture with > 100,000 colony-forming units/ml (CFU/ml) plus urinary symptoms (dysuria, frequency, urgency and/or suprapubic pain and/or fever); Pneumonia was defined as fever plus radiological findings on chest X-ray consistent with pneumonia. …