Gram-negative rod bacteremia after cardiovascular surgery: Clinical features and prognostic factors

Prolonged cardiopulmonary bypass time as predictive factor for bloodstream infection

Objectives

To evaluate the correlation between patient characteristics, operative variables and the risk of blood stream infection as well as the association of primary blood stream infection and adverse outcomes.

Methods

Clinical records of 6500 adult patients who underwent open heart surgery between February 2008 and October 2020 were analyzed. The microbiological pattern of the primary BSI and its association with adverse events, such as mortality and major cardiovascular events, were evaluated.

Results

Primary bloodstream infection was diagnosed in 1.7% (n = 108) of patients following cardiac surgery with the application of cardiopulmonary bypass. Most isolated bacteria were gram-negative bacillus groups, such as the Enterobacteriaceae family with Serrata marcescens in 26.26%, followed by the Enterococcaceae family with the Enterococcus faecalis in 7.39% and Enterococcus faecium in 9.14% as the most frequently identified bacteria. The postprocedural mortality, stroke rate p < 0.001, the incidence of postoperative new renal failure p < 0.001, and the renal replacement therapy p < 0.001 were significantly higher in the primary BSI group. Aortic cross-clamp time >120 min, OR 2.31 95%CI 1.34 to 3.98, perfusion time >120 min, OR 2.45 95%CI 1.63 to 3.67, and duration of the intervention >300min, OR 2.78 95%CI 1.47 to 5.28, were significantly related to the primary BSI.

Conclusion

The gram-negative bacillus was the most common microorganism identified in BSI after cardiovascular operations using cardiopulmonary bypass. Patients on dialysis prior to cardiac surgery are at higher risk for having BSI. Enteric bacterial translocation after prolonged cardiopulmonary bypass is a possible mechanism of early primary bloodstream infection in these patients. In patients at high risk, prophylactic use of an antibiotic regimen with broader gram-negative bacteria coverage should be considered, especially in those with prolonged cardiopulmonary bypass and intervention time.

Pseudomonas aeruginosa Pneumonia: Evolution of Antimicrobial Resistance and Implications for Therapy

Pseudomonas aeruginosa (PA), a non-lactose-fermenting gram-negative bacillus, is a common cause of nosocomial infections in critically ill or debilitated patients, particularly ventilator-associated pneumonia (VAP), and infections of urinary tract, intra-abdominal, wounds, skin/soft tissue, and bloodstream. PA rarely affects healthy individuals, but may cause serious infections in patients with chronic structural lung disease, comorbidities, advanced age, impaired immune defenses, or with medical devices (e.g., urinary or intravascular catheters, foreign bodies). Treatment of pseudomonal infections is difficult, as PA is intrinsically resistant to multiple antimicrobials, and may acquire new resistance determinants even while on antimicrobial therapy. Mortality associated with pseudomonal VAP or bacteremias is high (> 35%) and optimal therapy is controversial. Over the past three decades, antimicrobial resistance (AMR) among PA has escalated globally, via dissemination of several international multidrug resistant "epidemic" clones. We discuss the importance of PA as a cause of pneumonia including health care-associated pneumonia, hospital-acquired pneumonia, VAP, the emergence of AMR to this pathogen, and approaches to therapy (both empirical and definitive).

The value of prophylactic antibiotics in coronary artery bypass graft surgery: A review of literature

Infections have a significant impact on increasing both the morbidity and mortality rate of patients who have undergone coronary artery bypass graft (CABG) surgery. Infection after CABG imposes a clinical and economic burden on patients and health care organizations; therefore, prevention should be on the agenda. This review will focus on the value of using prophylactic antibiotics in coronary artery bypass graft surgery (CABG). Prophylactic antibiotics like cephalosporin and vancomycin are more commonly used antibiotics and are strongly associated with reduced infection risk in patients. The results showed that using antibiotics during the perioperative period and after CABG is an effective strategy for reducing post-infection problems without compromising the patients' clinical outcomes. Diabetic patients are prone to postoperative infection after CABG, however, prophylactic antibiotics should not be the only strategy used to reduce the risk of postoperative infection in diabetic patients. Perioperative glycaemic control is essential for diabetic patients undergoing CABG. Appropriate antibiotic prophylaxis has a great impact on preventing infection after CABG but duration and selecting appropriate antibiotic is important. Standardizing the use of antibiotic prophylaxis reduces the rate of infection and unwanted bacterial resistance, which could subsequently reduce economic costs to patients and public health.

Antimicrobial susceptibilities of the ertapenem-non-susceptible non-carbapenemase-producing Enterobacterales isolates causing intra-abdominal infections in the Asia-Pacific region during 2008-2014: Results from the Study for Monitoring the Antimicrobial Resistance Trends (SMART)

OBJECTIVES

To investigate the susceptibility profiles amongst ertapenem-non-susceptible non-carbapenemase-producing Enterobacterales (ETP-NS-non-CPE) isolates.

METHODS

Minimum inhibitory concentrations (MICs) of 404 ETP-NS-non-CPE isolates collected from different intra-abdominal infection (IAI) sites amongst patients in the Asia-Pacific region during 2008-2014 were determined using the broth microdilution method. The susceptibility results were interpreted according to the MIC breakpoints recommended by the Clinical and Laboratory Standards Institute (CLSI) in 2018. The MICs data of several agents were evaluated based on their published pharmacokinetic/pharmacodynamic (PK/PD) profiles.

RESULTS

The majority (>84%) of IAI-ETP-NS-non-CPE isolates - including Escherichia coli (n=83), Klebsiella pneumoniae (n=91) and Enterobacter species (n=210) - were susceptible to imipenem and amikacin. The 193 hepatobiliary ETP-NS-non-CPE isolates exhibited a trend of lower cefepime MIC (≤4mg/L) distribution than those (n=145) cultured from the peritoneal space (P=0.058). Amongst the ETP-NS-non-CP Enterobacter isolates, 65.7% displayed a cefepime MIC≤4mg/L. In addition, compared with Escherichia coli and Klebsiella pneumoniae isolates, 82.9% and 72.9% of the ETP-NS-non-CP Enterobacter isolates were susceptible to levofloxacin and ciprofloxacin, respectively. Of note, 74.5% and 70.3% of the ETP-NS-non-CP Enterobacter isolates cultured from the hepatobiliary tract and peritoneal space exhibited a ciprofloxacin MIC≤2mg/L and ≤0.25mg/L, respectively. Imipenem and amikacin showed good in vitro susceptibility rates against the IAI-ETP-NS-non-CPE isolates. The hepatobiliary ETP-NS-non-CPE displayed lower cefepime MICs than those cultured from the peritoneal space. Additionally, a significant fraction of IAI-ETP-NS-non-CP Enterobacter isolates exhibited ciprofloxacin MIC ≤ 2mg/L.

CONCLUSION

Based upon the PK/PD analyses, ciprofloxacin, imipenem and cefepime are probably effective against IAI-ETP-NS-non-CPE isolates.

Cardiopulmonary Bypass Time Predicts Early Postoperative Enterobacteriaceae Bloodstream Infection

BACKGROUND

A bloodstream infection in patients undergoing cardiovascular operations is crucial because it can result in significantly worse outcomes. However, microbiological patterns have rarely been investigated in these patients.

METHODS

We retrospectively reviewed the data of 1,041 adult patients who underwent cardiovascular operations using cardiopulmonary bypass from January 2013 to December 2017 at the National Cheng Kung University Hospital, Tainan, Taiwan. The microbiological pattern and associated variables were analyzed in patients with early postoperative primary bloodstream infection.

RESULTS

Primary bloodstream infection developed in 28 patients (2.7%) within 7 days after cardiovascular operations using cardiopulmonary bypass. In patients with early primary bloodstream infection, 36 microorganisms were isolated, and a gram-negative bacillus was identified to be the predominant pathogen (28 of 36 [77.8%]). The most common microorganisms comprised the Enterobacter (n = 8) and Acinetobacter (n = 7) species, and 16 of the 28 gram-negative bacilli belonged to the Enterobacteriaceae family. Compared with those without postoperative bloodstream infection, patients with Enterobacteriaceae family-related early postoperative bloodstream infections had a significantly longer cardiopulmonary bypass time and also worse early and late survival rates.

CONCLUSIONS

Most patients with early primary bloodstream infection after cardiovascular operations using cardiopulmonary bypass were infected with gram-negative bacilli, and the Enterobacteriaceae family was the most common microorganism observed. Endogenous bacterial translocation after prolonged cardiopulmonary bypass is a possible mechanism of Enterobacteriaceae family-related early primary bloodstream infection in these patients. Prophylactic use of an antibiotic regimen with broader gram-negative bacteria coverage in cardiovascular surgical patients with prolonged cardiopulmonary bypass should be considered.

The incidence rate, trend and microbiological aetiology of prosthetic joint infection after total knee arthroplasty: A 13 years' experience from a tertiary medical center in Taiwan

BACKGROUND/PURPOSE

Total knee arthroplasty (TKA) improves the patient's quality of life by relieving pain, correcting the deformity, and helping the patient resume normal activities. However, post-TKA prosthetic joint infection leads to implant failure, is difficult to treat, and causes a significant burden both economically and health-wise. Therefore, an understanding of the current trends in this infection and microbiology data is essential for preventing and treating it.

METHODS

A retrospective study was conducted on 10,768 patients who underwent primary TKA at Taipei Veterans General Hospital, Taiwan, from 2002 to 2014. The incidence of post-TKA prosthetic joint infection in different time periods was investigated, and microbiological results in early- (<3 months post-TKA) and delay-onset prosthetic joint infection were analyzed.

RESULTS

The 2 years incidence of post-TKA prosthetic joint infection was 1.93% (2002-2006), 1.05% (2007-2010), and 0.76% (2011-2014). The incidence of post-TKA prosthetic joint infection decreased significantly from 2002 to 2014. Although Staphylococcus species was most commonly isolated, a significantly higher proportion of gram-negative bacteria were isolated from early-onset compared with delay-onset post-TKA prosthetic joint infection patients: 9/29 (31.0%) versus 13/100 (13%); p = 0.023.

CONCLUSIONS

The results showed that the risk of post-TKA prosthetic joint infection is decreasing. Microbiology results showed that early-onset post-TKA prosthetic joint infection is associated with a higher risk of gram-negative bacterial infection. Physicians should be aware of this risk in order to correctly select empirical agents.