Temporal Trends in Deep SSIs After Six Orthopedic Procedures


Surgical site infections (SSIs) are important postoperative complications. They are associated with a longer hospital stay, reoperation, temporary prosthesis removal, and prolonged antimicrobial therapy.

In this study, we evaluated the incidence of SSIs after total hip arthroplasty (THA) and total knee arthroplasty (TKA). We also assessed the risk factors associated with SSIs.

Overall Incidence

SSIs are among the most common healthcare-associated infections (HAIs), but their incidence is variable. Efforts have been made to minimize their occurrence by implementing prophylactic antibiotic use during surgery, reducing the frequency of repeat surgeries, and improving hygiene conditions. However, there are still significant SSI rates in low- and middle-income countries (LMICs) [1,2].

To evaluate the temporal trends of deep surgical site infections (SSIs) after six orthopedic procedures, we performed a retrospective case-control study at two tertiary-care hospital-affiliated centers. We included 4818 patients who underwent elective orthopaedic procedures and developed SSIs within 1 year after their operation.

A total of 74 SSIs were identified, with an overall incidence rate of 1.5%. Approximately half of the SSIs were caused by Staphylococcus aureus, and coagulase-negative staphylococci were responsible for the other half. Five risk factors were independently associated with SSI development: diabetes mellitus, morbid obesity, tobacco smoking, surgical duration>75th percentile, and ALB 35.0 g/L. These findings may improve the preoperative assessment of patients and optimisation of modifiable risk factors.

Organism-Specific Incidence

Surgical site infections (SSIs) are among the most common and costly health care-associated infections and can have a major impact on patient outcomes. In addition, SSIs are often multidrug-resistant and exacerbate the severity of complications. Hence, they are important to control and prevent in the operating room.

In this study, we performed active surveillance for hip and knee prostheses in 25 public hospitals equipped with orthopaedic units located in two Italian regions. Data were collected from the infection control nurses of each center over an 8-month period.

SSIs were identified in 45 cases, with an incidence rate of 1*9/100 person-years (95% confidence interval [CI] 1*4-2*5). Thirty-six percent of SSIs occurred during hospitalization and 95*3% within 90 days post-operation. The most frequent SSI-causative organism was Staphylococcus aureus.

Orthopedic – Polymicrobial Infections

Despite the use of preventive measures and advances in surgical techniques, deep infections caused by microorganisms continue to occur after orthopedic procedures. This is particularly true in developing countries, where adherence to infection control guidelines and resources are limited and inadequate.

A variety of pathogens, including Staphylococcus aureus, Enterobacteriaceae, Pseudomonas aeruginosa, Streptococci, and anaerobes, have been found to contribute to the development of polymicrobial infections. These are characterized by organisms belonging to different kingdoms, genera, species, and substrains.

Polymicrobial infections also develop in patients with cystic fibrosis, where chronic airway inflammation leads to colonization of these patients by several pathogens, including S. aureus, Pseudomonas species, Haemophilus influenzae, and Burkholderia cepacia. The development of polymicrobial infections is a complex process that includes the interaction between the host and microorganisms. It requires careful assessment of radiologic imaging, blood, synovial fluid. Histologic testing to establish the presence of an infectious syndrome. Ultimately, accurate diagnosis is a key factor in optimizing patient outcomes.

Orthopedic – Cutibacterium acnes

The microorganism cutibacterium acnes is a commensal gram-positive bacterium that has been implicated in orthopedic implant-related infections. It produces a range of pathogenic factors, including biofilm formation, and is associated with increased drug resistance.

A pyogenic joint infection (PJI) with this bacterium is a rare but persistent infection after surgery. It occurs in a small percentage of patients undergoing total hip or knee arthroplasty, and is often asymptomatic. The PJIs are often difficult to diagnose, due to the fact that MSIS criteria for PJI might not apply to this type of infection.

To reduce the risk of C. acnes contamination during and after orthopaedic procedures, we compared three methods to obtain intraoperative cultures of skin swabs: sterile ethanol preparation (PES), a saline swab, and Z-swab with antibiotic prophylaxis (L). Cultures were incubated for 14 d at 37degC.