Infectious complications following major heart surgery from the day of the surgery to hospital discharge.

BACKGROUND: At some point in their lives, many people will require major heart surgery (MHS). Patients are generally older adults with various risk factors for infection. However, the incidence of infection after MHS is poorly known, as reported infection data are frequently biased due to different factors like the surgical procedure, postoperative timing, and infectious syndromes or etiologic agents, among others. In addition, most patient data are retrospectively obtained. PURPOSE AND METHODS: Data were prospectively collected regarding the incidence of all nosocomial infections produced from the time of surgery to hospital discharge in a cohort of 800 adults consecutively undergoing a MHS procedure. RESULTS: During postoperative hospitalization, 124 of the 800 participants developed one or more infections (15.5%): during their ICU stay in 68 patients (54.8%), during their stay on the general ward post ICU in 50 (40.3%), and during their stay in both wards in 6 (4.8%). The most common infections were pneumonia (related or not to mechanical ventilation), surgical site and bloodstream. As etiological agents, 193 pathogens were isolated: mostly Gram-negative bacilli (54.4%), followed by Gram-positive bacteria (30%), viruses (4.6%) and fungi (1.5%). In our cohort, all-cause mortality was recorded in 33 participants (4.1%) and 9 infection-related deaths (1.1%) were produced. Among subjects who developed infections, overall mortality was 13.7% and in those who did not, this was only 2.3%. CONCLUSION: Infection following MHS remains frequent and severe. Our data suggest that hospital-acquired infection studies should consider episodes of infection in all populations during their entire hospital stay and not only those related to specific clinical syndromes or acquired while the patient is in intensive care.

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

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.

Do lower respiratory tract samples contribute to the assessment of carriage of Staphylococcus aureus in patients undergoing mechanical ventilation after major heart surgery?

Colonization by Staphylococcus aureus is regularly assessed in patients undergoing major heart surgery (MHS). Despite pre-surgical decontamination attempts, a significant proportion of MHS patients remain colonized by S. aureus at the time of surgery. Nasal sampling can be improved by sampling extra-nasal areas. We evaluated whether processing lower respiratory tract (LRT) secretions enhanced the detection of S. aureus after MHS. Following a standard protocol, nasal swabs and LRT aspirates were obtained from all of the study patients at the time of surgery or in the immediate postoperative period. One swab was used for culture in the microbiology laboratory, and a second swab was used for the Xpert SA Nasal Complete assay. According to our definition of colonization (culture positive and/or PCR positive), 31 of 115 patients (26.9%) were colonized at the time of surgery. Among these, LRT samples only were positive in three patients (2.6% of the whole population and 9.7% of the carriers). The remaining 28 were either positive in the nasal sample or positive in both samples. The yield of the detection of colonization by S. aureus by including also LRT samples in patients undergoing MHS is limited and must be balanced with laboratory workload and demands on laboratory personnel. Trial registration: Clinical trials.gov NCT02640001.

Impact of selective digestive decontamination without systemic antibiotics in a major heart surgery intensive care unit.

PURPOSE: The incidence density of ventilator-associated pneumonia (VAP) is higher in patients undergoing major heart surgery than in other populations, despite the introduction of bundles of preventive measures, because many risk factors are not amenable to intervention. Selective digestive decontamination (SDD) has been shown to be efficacious for decreasing the frequency of VAP, although it has not been incorporated into the routine of most intensive care units. The objective of our study was to evaluate the efficacy of SDD without parenteral antibiotics for preventing VAP in a major heart surgery intensive care unit. METHODS: We compared the incidence of VAP before the introduction of SDD (17 months) and during the 17 months after the introduction of SDD and examined its ecologic influence. RESULTS: The rates of VAP in the overall population before and during the intervention were 16.26/1000 days and 6.80 episodes/1000 days of mechanical ventilation, respectively (P = .01). The rates of VAP in the 173 patients remaining under mechanical ventilation > 48 hours after surgery were, respectively, 25.85/1000 days of mechanical ventilation versus 12.06 episodes/1000 days of mechanical ventilation (P = .04). We found a significant reduction in the number of patients with multidrug-resistant microorganisms (P = .01) in the second period of the study. CONCLUSIONS: Our study shows that SDD without parenteral antibiotics can reduce the incidence of VAP in high-risk patients after major heart surgery, with no significant ecologic influence.

T2MR contributes to the very early diagnosis of complicated candidaemia. A prospective study.

Objectives: Diagnosis of complicated candidaemia represents a challenge for clinicians since early clinical manifestations may be non-specific and difficult to identify, thus precluding an appropriate treatment. Patients and methods: This was a multicentre prospective study for predicting complicated episodes in patients with bloodstream infection caused by Candida species, while assessing the value of follow-up blood cultures (BCs) and the persistence of positive results for T2Candida MR (T2MR) and blood ß-d-glucan (BDG) tests. Immediately after the first positive BC yielding Candida species, samples were obtained on days 0, +2, +4, +7 and +14, to simultaneously perform follow-up BC, T2MR and BDG. An episode of candidaemia was defined as 'complicated' when (i) it caused septic metastasis; and/or (ii) it was the cause of the patient's death. Results: From January to June 2017, 30 patients were enrolled in the study. Of these, nine (30%) had complicated candidaemia. Values of persistently positive samples for the prediction of complicated episodes for BCs, T2MR and BDG, respectively, were as follows: sensitivity (44.4%, 100%, 100%); specificity (76.1%, 76.1%, 38.9%); positive predictive value (PPV) (44.4%, 64.2%, 40.9%) and negative predictive value (NPV) (76.1%, 100%, 100%). In multivariate analysis, having a positive T2MR within the first 5 days was associated with an almost 37-fold higher risk of developing complicated candidaemia. Conclusions: The T2MR test performed in patients with proven candidaemia may be a better marker of complicated infection than follow-up BCs or BDG. It is possible that this test may change current clinical practice, influencing the length and type of antifungal therapy in this population.

Vascular catheter colonization: surveillance based on culture of needleless connectors.

BACKGROUND: Superficial culture has a high negative predictive value in the assessment of catheter tip colonization (CC) and catheter-related bloodstream infection (C-RBSI). However, the process of hub culture requires the hubs to be swabbed, and this carries a risk of dislodging the biofilm. At present, most catheter hubs are closed by needleless connectors (NCs) that are periodically replaced. Our objective was to compare the yield of SC (skin + hub culture) with that of skin + NC culture in the assessment of CC and C-RBSI. METHODS: During 5 months, we included the patients on the Major Heart Surgery ICU when a central venous catheter (CVC) remained in place ≥7 days after insertion. SCs were taken simultaneously when the NC was withdrawn and processed by the semi-quantitative method, even when the catheter was not removed. All catheter tips were cultured. All NCs belonging to a single catheter lumen were individually flushed with 100 µl of brain-heart infusion (BHI) broth. We considered the lumen to be colonized when ≥1 NC culture from the lumen flush was positive. We collected a total of 60 catheters. RESULTS: The overall CC rate was 15.0 %, and we confirmed two episodes of C-RBSI. The validity values after the comparison of SCs with skin + NC culture for prediction of CC were the following: sensitivity 66.7 % vs. 77.8 %, and negative predictive value 93.6 % vs. 93.1 %. The sensitivity and negative predictive value for prediction of C-RBSI was 100 % for both SC and skin + NC culture. CONCLUSION: The combination of skin and flushed NC culture can be an alternative to conventional SC for ruling out CC and C-RBSI.

A Prospective Monitoring Study of Cytomegalovirus Infection in Non-Immunosuppressed Critical Heart Surgery Patients.

BACKGROUND: Reactivation of cytomegalovirus (CMV) has been reported occasionally in immnunocompetent patients in the intensive care unit (ICU). The epidemiology and association of CMV infection with adverse outcome is not well defined in this population. Patients undergoing major heart surgery (MHS) are at a particularly high risk of infection. CMV infection has not been systematically monitored in MSH-ICU patients. METHODS: We assessed CMV plasma viremia weekly using a quantitative polymerase chain reaction assay in a prospective cohort of immunocompetent adults admitted to the MHS-ICU for at least 72 hours between October 2012 and May 2013. Risk factors for CMV infection and its potential association with continued hospitalization or death by day 30 (composited endpoint) were assessed using univariate and multivariate logistic regression analyses. RESULTS: CMV viremia at any level was recorded in 16.5% of patients at a median of 17 days (range, 3-54 days) after admission to the MHS-ICU. Diabetes (adjusted OR, 5.6; 95% CI, 1.8-17.4; p=0.003) and transfusion requirement (>10 units) (adjusted OR, 13.7; 95% CI, 3.9-47.8; p<0.001) were independent risk factors associated with CMV reactivation. Reactivation of CMV at any level was independently associated with the composite endpoint (adjusted OR, 12.1; 95% CI, 2.3-64; p=0.003). CONCLUSION: Reactivation of CMV is relatively frequent in immunocompetent patients undergoing MHS and is associated with prolonged hospitalization or death.

Cultures of Needleless Connectors Are Useful for Ruling Out Central Venous Catheter Colonization.

Semiquantitative cultures of skin surrounding intravascular catheter entry sites and catheter hubs have high negative predictive values for catheter tip colonization. However, culturing samples from the inner side of the hub requires the catheter to be manipulated, thus increasing the risk of migration of microorganisms into the bloodstream. Today, hubs are closed using needleless connectors (NCs). Cultures of NCs could predict catheter colonization. Our objective was to compare the yield of NC sonicate cultures for prediction of catheter colonization with that of hub cultures. For 6 months, we prospectively collected all short-term central lines and systems removed from patients admitted to the cardiac surgery postoperative care unit, irrespective of the reason for withdrawal. Hub cultures were obtained immediately before withdrawal and were cultured using a semiquantitative method. Catheter tips were cultured using the roll-plate technique and sonication, and NCs were cultured using a semiquantitative technique after sonication. We considered NCs to be colonized when ≥1 culture was positive. We collected a total of 75 central systems. The catheter colonization rate was 10.7%. The rates for hub and NC colonization were 6.7% and 12.0%, respectively. The validity values for hubs and NCs for prediction of catheter colonization were as follows: sensitivity, 25.0% and 87.5%; specificity, 95.5% and 97.0%; positive predictive value, 40.0% and 77.8%; negative predictive value, 91.4% and 98.5%; validity index, 88.0% and 96.0%, respectively. Cultures of closed NCs can be used to rule out catheter tip colonization and are superior to hub cultures in ruling out short-term central venous catheter colonization.

Ethanol lock therapy (E-Lock) in the prevention of catheter-related bloodstream infections (CR-BSI) after major heart surgery (MHS): a randomized clinical trial.

BACKGROUND: Lock-therapy with antimicrobials has been used for the treatment and prevention of catheter-related bloodstream infections (CR-BSI). Experiences with Ethanol-Locks (E-locks) have included therapeutic interventions with variable results. Patients undergoing Major Heart Surgery (MHS) are a high-risk population for CR-BSI.The aim of this study was to assess the efficacy and tolerance to E-Locks in the prevention of CR-BSI of patients undergoing MHS. METHODS AND FINDINGS: This is an academic, prospective, randomized, non-blinded and controlled clinical trial assessing the incidence of CR-BSI of patients with E-locks (E-lock) and the tolerance to the procedure in comparison with patients receiving conventional catheter-care (CCC). Patients undergoing MHS with intravascular catheters for more than 48 hours were randomly assigned into treatment or control group by a computer-generated list of randomly assigned numbers. In the treatment group, all their catheter lumens were locked with an ethanol solution at 70% for two hours, every three days (E-Locks). The control group received conventional catheter-care (CCC). Overall, 200 patients with 323 catheters were included in the study, which was stopped after 10 months due to adverse events. Of them, 179 catheters (113 patients) had E-Locks and 144 catheters (87 patients) were CCC. Euroscore Surgical Risk in both groups was 4.04 vs 4.07 p = 0.94 respectively. The results for the E-Locks and CCC were as follows: Incidence of CR-BSI/1000 days of exposure 2.1 vs 5.2 (p = 0.33), catheter tip colonization 14 (7.8%) vs 6 (4.2%) patients (p = 0.17), median length of hospital stay, 15 vs 16 days (p = 0.77). Seven patients (6.19%), all in the ethanol branch, had to discontinue the trial due to intolerance or adverse events. CONCLUSIONS: We do not recommend prophylaxis of CR-BSI with ethanol-lock on a routine basis in patients undergoing Major Heart Surgery. TRIAL REGISTRATION: Clinical Trials.gov NCT01229592.

Impact of four sequential measures on the prevention of ventilator-associated pneumonia in cardiac surgery patients.

INTRODUCTION: Ventilator-associated pneumonia (VAP) is the most frequent infection in patients admitted to intensive care units. METHODS: We compared rates of VAP, days on mechanical ventilation (MV), and cost of antimicrobial agents before and during implementation. RESULTS: We collected data from 401 patients before the intervention and from 1,534 patients during the intervention. Both groups were comparable. No significant differences in EuroSCORE were observed between the patients of both periods (6.4 versus 6.3; P = 0.7). The rates of VAP (episodes/1,000 days of ventilation) were, respectively, 23.9 versus 13.5 (P = 0.005). Mean number of days of MV/1,000 days of stay was 507 versus 375 (P = 0.001), and the cost of antimicrobial therapy (Euros/1,000 days of stay) was €70,612 versus €52,775 (P = 0.10). The main effect of sequential application of preventive measures in time achieved a relative-rate reduction of VAP of 41% (IRR, 0.41; 95% CI, 0.28 to 0.62). The mortality rate before and during the intervention was 13.0% and 10.2%, respectively. CONCLUSIONS: A sequentially applied bundle of four preventive measures reduces VAP rates, days of MV, and the cost of antimicrobial therapy in patients admitted to the major heart surgery ICU. TRIAL REGISTRATION: Clinical Trials.gov: NCT02060045. Registered 4 February 2014.