Factors Associated with Post-Operative Conversion to Methicillin-ResistantStaphylococcus AureusPositivity or Infection in Initially MRSA-Negative Patients

Prophylactic Effect of Vancomycin on Infection after Cranioplasty in Methicillin-Resistant Staphylococcus Aureus Carriers with Traumatic Brain Injury

Objective

Methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant coagulase negative staphylococci (MRCNS) are major causes of neurosurgical infection. Nasal colonization of MRSA is the most important risk factor and MRSA screening can be a screening method to identify MRSA and MRCNS colonization. We retrospectively evaluated prophylactic effect of vancomycin on MRSA or MRCNS surgical site infection (SSI) after cranioplasty following decompressive craniectomy (DC) after traumatic brain injury (TBI) in MRSA carriers.

Methods

The study included 21 patients who were positive in MRSA screening before cranioplasty. These patients underwent DC after TBI and subsequent cranioplasty with autologous bone. The patients were separated into SSI group and no SSI group according to the development of SSI due to MRSA or MRCNS after cranioplasty. Mean follow-up period after cranioplasty was 23.5±22.8 months (range, 3 to 73 months). The rate of MRSA or MRCNS SSI and factors including the prophylactic preoperative antibiotics were compared between groups.

Results

The rate of MRSA or MRCNS SSI was 23.8% (5/21 patients). Mean time from cranioplasty to confirm the SSI was 19.6±10.9 days (6 to 63 days). The rate of MRSA or MRCNS SSI was significantly different from the use of preoperative prophylactic antibiotics (p=0.047). MRSA or MRCNS SSI developed in 1 of 13 patients (7.6%) who received vancomycin and in 4 of 8 patients (50%) who received 3rd generation cephalosporin.

Conclusion

Preoperative MRSA screening and administration of vancomycin as a preoperative prophylactic antibiotic should be considered in MRSA carriers who are scheduled to cranioplasty to reduce MRSA or MRCNS SSI.

Epidemiology of methicillin-resistant Staphylococcus aureus carriage and MRSA surgical site infections in patients undergoing colorectal surgery: a cohort study in two centers

BACKGROUND

Surgical site infections (SSIs) after colorectal surgery usually are caused by commensal intestinal bacteria. Methicillin-resistant Staphylococcus aureus (MRSA) may be responsible for additional SSI-related morbidity. The aim of this retrospective cohort study was to describe the epidemiology of SSIs caused by MRSA after colorectal surgery in two tertiary-care centers, one in Geneva, Switzerland (G), and the other in Chicago, Illinois (C).

METHODS

Adult patients undergoing colorectal resections during periods of universal screening for MRSA on admission were identified retrospectively. Demographic characteristics, surgery-related factors, and occurrence of MRSA SSI were compared in patients with and without MRSA carriage before surgery.

RESULTS

There were 1,069 patients (G=194, C=875) with a median age of 67 years fulfilling the inclusion criteria. Of these, 45 patients (4.2%) had a positive MRSA screening result within 30 days before surgery (G=18, C=27; p<0.001). Ten patients (0.9%; G=6, C=4) developed MRSA SSI, detected a median of 17.5 days after surgery, but only two of them were MRSA-positive before surgery. Nine of the 45 MRSA carriers identified by screening received pre-operative prophylaxis with vancomycin (G 6/18, C 3/27), and 17 of these patients (37.8%; G 7/18, C 10/27) were started on MRSA decolonization therapy before surgery. Pre-operative administration of either decolonization or vancomycin was not protective against MRSA SSI (p=0.49).

CONCLUSION

Methicillin-resistant S. aureus seems to be an infrequent cause of SSI after colorectal resections, even in MRSA carriers. Systematic universal screening for MRSA carriage prior to colorectal surgery may not be beneficial for the individual patient. Post-operative factors seem to be important in MRSA infections, as the majority of MRSA SSIs occurred in patients negative for MRSA carriage.