Colonization of the nasal airways by Staphylococcus aureus on admission to a major heart surgery operating room: A real-world experience

Abstract

Introduction: Nasal swab culture is used to identify Staphylococcus aureus colonization, as this is a major risk factor for surgical site infection (SSI) in patients who are going to undergo major heart surgery (MHS). We determined nasal carriage of S. aureus in patients undergoing MHS by comparing the yield of a conventional culture with that of a rapid molecular test (Xpert® SA Nasal Complete, Cepheid).

Methods: From July 2015 to April 2017, all patients who were to undergo MHS were invited to participate in the study. We obtained two nasal cultures from each patient just before entering the operating room, independently of a previous test for the determination of nasal colonization by this microorganism performed before surgery. One swab was used for conventional culture in the microbiology laboratory, and the other was used for the rapid molecular test. We defined nasal colonization as the presence of a positive culture for S. aureus using either of the two techniques. All patients were followed up until hospital discharge or death.

Results: Overall, 57 out of 200 patients (28.5%) were colonized by S. aureus at the time of surgery. Thirty-three patients had both conventional culture- and PCR-positive results. Twenty-four patients had a negative culture and a positive PCR test. Only twenty-one percent (12/57) of colonized patients had undergone an attempt to decolonise before the surgical intervention.

Conclusion: A significant proportion of patients undergoing MHS are colonized by S. aureus in the nostrils on entering the operating room. New strategies to prevent SSI by this microorganism are needed. Rapid molecular tests immediately before MHS, followed by immediate decolonisation, must be evaluated. Trial Registration Clinical Trials.gov NCT02640001.

Keywords: Cirugía cardiaca mayor; Colonización nasal; Laboratory diagnostic techniques; Major heart surgery; Nasal colonization; Prevención de infección de la herida quirúrgica; Staphylococcus aureus; Surgical site infection prevention; Técnicas diagnósticas de laboratorio.