Infections and outcomes after cardiac surgery-The impact of outbreaks traced to transesophageal echocardiography probes

Abstract

Background: Infections are a frequent complication of cardiac surgery. The intraoperative use of transesophageal echocardiography (TEE) may be an underrecognized risk factor for post-operative infections. The aim of this study was to investigate infection rates and outcomes after cardiac surgery in a nationwide cohort, especially in relation to periods where surface damaged TEE probes were used.

Methods: This was a retrospective, observational study at Landspitali University Hospital. All consecutive cardiac surgery patients from 1 January 2013 to 31 December 2017 were included. Patients' charts were reviewed for evidence of infection, post-operative complications or death.

Results: During the study period, 973 patients underwent cardiac surgery at Landspitali and 198 (20.3%) developed a post-operative infection. The most common infections were: Pneumonia (9.1%), superficial surgical site (5.7%), bloodstream (2.8%) and deep sternal wound (1.7%). Risk factors for developing an infection included: The duration of procedure, age, insulin-dependent diabetes, EuroScore II, reoperation for bleeding and an operation in a period with a surface damaged TEE probe in use. Twenty-two patients were infected with a multidrug resistant strain of Klebsiella oxytoca, 10 patients with Pseudomonas aeruginosa and two patients developed endocarditis with Enterococcus faecalis. All three pathogens were cultured from the TEE probe in use at respective time, after decontamination. The 30-day mortality rate in the patient cohort was 3.2%.

Conclusions: The intraoperative use of surface damaged TEE probes caused two serious infection outbreaks in patients after cardiac surgery. TEE probes need careful visual inspection during decontamination and probe sheaths are recommended.

Keywords: cardiac surgery; nosocomial infections; pneumonia; post-operative complications; transesophageal echocardiography.

Figure 1

The tip of one of the transesophageal echocardiography probes in use during the study period. With magnification and specific lighting used in this photograph, numerous superficial scratches and a crack (arrow) in the plastic casing can be visualized. The damage was not obvious to the naked eye. The outbreak strains of Pseudomonas aeruginosa and Enterococcus faecalis were isolated from this crack, after the probe had been decontaminated and was ready for use (Photo: Thorkell Thorkelsson) [Colour figure can be viewed at wileyonlinelibrary.com]

Figure 2

Incidence of pneumonia after cardiac surgery over a 5‐year period. Each column represents one quarter year. Arrows indicate the time of TEE probe changes (November 2014 and April 2017)

Figure 3

The figure shows the proportion of all cardiac surgery patients with specific bacteria isolated from a post‐operative respiratory sample