Bloodstream infections among transplant recipients: results of a nationwide surveillance in Spain

Multidrug-resistant organism bloodstream infections in solid organ transplant recipients and impact on mortality: a systematic review

Background

Bloodstream infections (BSIs) cause significant morbidity and mortality in solid organ transplant (SOT) recipients. There are few data regarding the contribution of MDR organisms (MDROs) to these infections. We evaluated the resistance percentage of MDRO BSIs in SOT recipients and the associated mortality.

Methods

A systematic review of MEDLINE and Embase databases up to January 2024, for studies of adult SOT recipients that quantified MDRO BSI resistance percentage and/or associated crude mortality. MDROs studied were carbapenem-resistant Enterobacterales (CRE), Acinetobacter baumannii (CRAB) and Pseudomonas aeruginosa (CRPA), third-generation cephalosporin-resistant Enterobacterales (3GCR-E), MRSA and VRE. Resistance percentage and mortality outcomes were reported as median (IQR) and crude mortality (%), respectively.

Results

Of 945 studies identified, 52 were included. Most were retrospective (41/52) and/or single centre (37/52), and liver transplantation was the most frequently studied SOT type (22/52). High resistance percentages of BSIs were noted, ranging from 13.6% CRE for Enterobacterales to 59.2% CRAB for A. baumannii. Resistance percentage trends decreased over time, but these changes were not statistically significant. Asia had the highest resistance percentages for MRSA [86.2% (IQR 77.3%-94.6%)], 3GCR-E [59.5% (IQR 40.5%-66.7%)] and CRE [35.7% (IQR 8.3%-63.1%)]. North America had the highest VRE resistance percentages [77.7% (IQR 54.6%-94.7%)]. Crude mortality was 15.4%-82.4% and was consistently higher than for non-MDRO BSIs.

Conclusions

MDRO BSI resistance percentages were high for all pathogens studied (IQR 24.6%-69.4%) but there was geographical and temporal heterogeneity. MDRO BSIs were associated with high mortality in SOT recipients. Microbiological and clinical data in this vulnerable population were incomplete, highlighting the need for robust international multicentre studies.

Population Pharmacokinetic Analysis and Dosing Optimization of Colistin Sulfate in Lung Transplant Recipients with Pneumonia: A Prospective Study

OBJECTIVES

Currently, there is a lack of information on the clinical pharmacokinetics (PK), effectiveness, and safety of colistin sulfate in lung transplant recipients. This study aims to improve colistin sulfate dosing regimens and evaluate its population pharmacokinetics (PopPK) in lung transplant recipients.

METHODS

This study evaluated the clinical efficacy, microbiological efficacy, and adverse events of colistin sulfate in lung transplant recipients. The NONMEM program was employed to construct the PopPK model, and Monte Carlo simulations were executed to establish dosing regimens according to the probability of target attainment (PTA).

RESULTS

The study included 146 colistin sulfate concentrations, spanning from 0.05 to 4.18 mg/L from 39 lung transplant recipients with multidrug-resistant gram-negative bacteria. 26 (66.67%) patients successfully eradicated bacteria, and 30 (76.92%) patients had clinical cure or improvement. Additionally, only 2 (5.13%) patients developed colistin sulfate-related nephrotoxicity. The PK profile was effectively represented by a one-compartmental model with linear elimination. Creatinine clearance (CrCL) and concomitant furosemide use were recognized as covariates influencing the clearance of colistin sulfate. Based on the PTA results, a daily dosage of 1.5 million IU, divided into 2-3 administrations, could attain a PTA exceeding 90% for MIC ≤ 1 µg/mL at CrCL of about 110 mL/min. However, this regimen would lead to insufficient exposure for MIC ≥ 2 µg/mL.

CONCLUSION

The clearance of colistin sulfate is significantly influenced by concomitant furosemide use and renal function. The currently recommended dosing regimens by label sheet may result in subtherapeutic exposure for MIC exceeding 1 mg/L in lung transplant recipients.

Risk Factors for E2SKAPE Infections and Mortality Among Liver Transplant Recipients

PURPOSE

Infections caused by Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp (ESKAPE) plus Escherichia coli (E2SKAPE), in particular multidrug-resistant (MDR) E2SKAPE infections, occur frequently and pose a life-threatening to liver transplant (LT) recipients. To prevent E2SKAPE infections and improve the prognosis of LT recipients, the identification of risk factors for E2SKAPE infections and mortality is necessary.

METHODS

E2SKAPE pathogens were isolated and identified from clinical samples following standard microbiological procedures. All episodes of E2SKAPE infections and mortality documented among LT recipients were analyzed.

FINDINGS

A total of 83 episodes of E2SKAPE infections, including 75 (90.4%) episodes of MDR-E2SKAPE infections, occurred in 23.1% (53/229) of LT recipients. E. faecium was the dominant causative bacterium (37/83; 44.6%). The most common site of infections was the urinary tract (14/53; 26.4%). Sixteen (7%) patients died within 2 months after LT, and 7 deaths were E2SKAPE infections-related. Multivariate logistic regression analysis revealed that female sex [odds ratio (OR) = 3.665, 95% confidence interval (CI): 1.614-8.321, P = 0.002], duration of surgery ≥ 400 min [OR = 2.328, 95%CI: 1.151-4.707, P = 0.019], intraoperative red blood cell (RBC) transfusion ≥ 12U [OR = 2.542, 95%CI: 1.218-5.306, P = 0.013] and indwelling urethral catheter use ≥ 3 days [OR = 3.96, 95%CI: 1.309-11.981, P = 0.015] were independent risk factors for E2SKAPE infections after LT, and that only exposure to more than 2 intravenous antibiotics post-LT [OR = 0.318, 95%CI: 0.15-0.674, P = 0.003] was negatively associated with acquisition of E2SKAPE infections. The predictors of crude mortality included female sex [OR = 4.822, 95%CI: 1.299-17.904, P = 0.019], creatinine on day 3 post-LT > 1.5 mg/dL [OR = 11.014, 95%CI: 2.985-40.637, P < 0.001], mechanical ventilation post-LT [OR = 10.724, 95%CI: 2.695-42.676, P = 0.001] and recipients with E2SKAPE infections [OR = 4.112, 95%CI: 1.169-14.47, P = 0.028].

IMPLICATIONS

A high incidence of E2SKAPE infections was noted in the early post-LT period. The most common infection site was the urinary tract, and the dominant pathogenic bacterium was E. faecium. Female sex, prolonged surgery time, massive RBC transfusion, or delayed urethral catheter removal were associated with E2SKAPE infections. Only exposure to more than 2 intravenous antibiotics post-LT was negatively related to the acquisition of E2SKAPE infections. The predictors of mortality included female sex, creatinine on day 3 post-LT>1.5 mg/dL, mechanical ventilation post-LT, and recipients with E2SKAPE infections.

Bacterial infections in solid organ transplant recipients

PURPOSE OF REVIEW

Bacteria are the leading cause of infections in solid organ transplant (SOT) recipients, significantly impacting patient outcome. Recently detailed and comprehensive epidemiological data have been published.

RECENT FINDING

This literature review aims to provide an overview of bacterial infections affecting different types of SOT recipients, emphasizing underlying risk factors and pathophysiological mechanisms.

SUMMARY

Lung transplantation connects two microbiotas: one derived from the donor's lower respiratory tract with one from the recipient's upper respiratory tract. Similarly, liver transplantation involves a connection to the digestive tract and its microbiota through the bile ducts. For heart transplant recipients, specific factors are related to the management strategies for end-stage heart failure based with different circulatory support tools. Kidney and kidney-pancreas transplant recipients commonly experience asymptomatic bacteriuria, but recent studies have suggested the absence of benefice of routine treatment. Bloodstream infections (BSI) are frequent and affect all SOT recipients. Nonorgan-related risk factors as age, comorbidity index score, and leukopenia contribute to BSI development. Bacterial opportunistic infections have become rare in the presence of efficient prophylaxis. Understanding the epidemiology, risk factors, and pathophysiology of bacterial infections in SOT recipients is crucial for effective management and improved patient outcomes.

The Burden and Impact of Early Post-transplant Multidrug-Resistant Organism Detection Among Renal Transplant Recipients, 2005-2021

Background

Reducing the burden of multidrug-resistant organism (MDRO) colonization and infection among renal transplant recipients (RTRs) may improve patient outcomes. We aimed to assess whether the detection of an MDRO or a comparable antibiotic-susceptible organism (CSO) during the early post-transplant (EPT) period was associated with graft loss and mortality among RTRs.

Methods

We conducted a retrospective cohort study of RTRs transplanted between 2005 and 2021. EPT positivity was defined as a positive bacterial culture within 30 days of transplant. The incidence and prevalence of EPT MDRO detection were calculated. The primary outcome was a composite of 1-year allograft loss or mortality following transplant. Multivariable Cox hazard regression, competing risk, propensity score-weighted sensitivity, and subgroup analyses were performed.

Results

Among 3507 RTRs, the prevalence of EPT MDRO detection was 1.3% (95% CI, 0.91%-1.69%) with an incidence rate per 1000 EPT-days at risk of 0.42 (95% CI, 0.31-0.57). Among RTRs who met survival analysis inclusion criteria (n = 3432), 91% (3138/3432) had no positive EPT cultures and were designated as negative controls, 8% (263/3432) had a CSO detected, and 1% (31/3432) had an MDRO detected in the EPT period. EPT MDRO detection was associated with the composite outcome (adjusted hazard ratio [aHR], 3.29; 95% CI, 1.21-8.92) and death-censored allograft loss (cause-specific aHR, 7.15; 95% CI, 0.92-55.5; subdistribution aHR, 7.15; 95% CI, 0.95-53.7). A similar trend was seen in the subgroup and sensitivity analyses.

Conclusions

MDRO detection during the EPT period was associated with allograft loss, suggesting the need for increased strategies to optimize prevention of MDRO colonization and infection.

Bloodstream infections after solid organ transplantation: clinical epidemiology and antimicrobial resistance (2016-21)

Background

Solid organ transplant (SOT) recipients are at risk of bloodstream infections (BSIs) with MDR organisms (MDROs).

Objectives

To describe the epidemiology of BSI in the year after several types of SOT, as well as the prevalence of MDRO infections in this population.

Methods

We conducted a single-centre, retrospective study of kidney, liver, heart, and multi-organ transplantation patients. We examined BSIs ≤1 year from SOT and classified MDRO phenotypes for Staphylococcus aureus, enterococci, Enterobacterales, Pseudomonas aeruginosa and Candida spp. We compared BSI characteristics between SOT types and determined risk factors for 90 day mortality.

Results

We included 2293 patients [1251 (54.6%) kidney, 663 (28.9%) liver, 219 (9.6%) heart and 160 (7.0%) multi-organ transplant]. Overall, 8.5% of patients developed a BSI. BSIs were most common after multi-organ (23.1%) and liver (11.3%) transplantation (P < 0.001). Among 196 patients with BSI, 323 unique isolates were recovered, 147 (45.5%) of which were MDROs. MDROs were most common after liver transplant (53.4%). The most frequent MDROs were VRE (69.8% of enterococci) and ESBL-producing and carbapenem-resistant Enterobacterales (29.2% and 27.2% of Enterobacterales, respectively). Mortality after BSI was 9.7%; VRE was independently associated with mortality (adjusted OR 6.0, 95% CI 1.7-21.3).

Conclusions

BSI incidence after SOT was 8.5%, with a high proportion of MDROs (45.5%), especially after liver transplantation. These data, in conjunction with local antimicrobial resistance patterns and prescribing practices, may help guide empirical antimicrobial selection and stewardship practices after SOT.

Postoperative Bloodstream Infection Is Associated with Early Vascular Complications in Pediatric Liver Transplant Recipients with Biliary Atresia

Bloodstream infection (BSI) after pediatric liver transplantation (PLT) is a common and severe complication that affects patient survival. Children with biliary atresia (BA) are at an increased risk for clinically significant infections. This study evaluated the impact of post-PLT BSI on clinical outcomes in children with BA. A total of 67 patients with BA aged <18 years who underwent PLT between April 2006 and September 2020 were analyzed and divided into two groups according to the occurrence of post-PLT BSI within 1 month (BSI vs. no BSI = 13 [19.4%] vs. 54 [80.6%]). The BSI group was significantly younger at the time of PLT and had a higher frequency of BSI at the time of PLT than the no BSI group. Early vascular complications within 3 months and reoperations were significantly more frequent in the BSI group. Univariate and multivariate analyses revealed that bacteremia within 1 month of PLT and graft-to-recipient weight ratio >4% were significantly associated with vascular complications. In conclusion, BSI after PLT is associated with increased vascular complications and reoperations. Proper control of bacterial infections and early liver transplantation before uncontrolled BSI may reduce vascular complications and unexpected reoperations in children with BA.

Investigating infectious outcomes in adult patients undergoing solid organ transplantation: A retrospective single-center experience, Paris, France

OBJECTIVES

This study described the demographic characteristics, clinical presentation, treatment, and outcomes of solid organ transplant recipients who were admitted to our center for infection. It also determined factors associated with a poor outcome, and compares early and late period infections.

METHODS

In this retrospective observational study, conducted at a tertiary care center in France between October 2017 and March 2019, infectious outcomes of patients with solid organ transplant where studied.

RESULTS

A total of 104 patients were included with 158 hospitalizations for infection. Among these 104 patients, 71 (68%) were men. The median age was 59 years old. The most common symptoms on admission were fever (66%) and chills (31%). Lower respiratory tract infections were the most common diagnosis (71/158 hospitalizations). Urinary tract infections were frequently seen in kidney transplant recipients (25/60 hospitalizations). One or more infectious agents were isolated for 113 hospitalizations (72%): 70 bacteria, 36 viruses and 10 fungi, with predominance of gram-negative bacilli (53 cases) of which 13 were multidrug-resistant. The most frequently used antibiotics were third generation cephalosporins (40 cases), followed by piperacillin-tazobactam (26 cases). We note that 25 infections (16%) occurred during the first 6 months (early post-transplant period). Patients admitted during the early post-transplant period were more often on immunosuppressive treatment with prednisone (25/25 VS 106/133) (p = 0.01), mycophenolic acid (22/25 VS 86/133) (p = 0.03), presented for an urinary tract infection (10/25 VS 25/133) (p = 0.04) or a bacterial infection (17/25 VS 53/133) (p = 0.01). Patients with later infection had more comorbidities (57/83 VS 9/21) (p = 0.03), cancer (19/83 VS 0/21) (p = 0.04) or were on treatment with everolimus (46/133 VS 0/25) (p = 0.001). During 31 hospitalizations (20%), patients presented with a serious infection requiring intensive care (n = 26; 16%) or leading to death (n = 7; 4%). Bacteremia, pulmonary and cardiac complications were the main risk factors associated with poor outcome.

CONCLUSION

Infections pose a significant challenge in the care of solid organ transplant patients, particularly those with comorbidities and intensive immunosuppression. This underscores the crucial importance of continuous surveillance and epidemiologic monitoring within this patient population.

Candidemia in thoracic solid organ transplant recipients: Characteristics and outcomes relative to matched uninfected and bacteremic thoracic organ transplant recipients

BACKGROUND

Little is understood about the risk factors and outcomes from candidemia in thoracic solid organ transplant recipients.

METHODS

This is a single-center retrospective cohort study of patients undergoing heart or lung transplant between January 1, 2013 and December 31, 2022. We performed two comparisons among heart and lung transplant recipients: (1) recipients with candidemia versus matched, uninfected recipients, and (2) recipients with candidemia versus recipients with bacteremia.

RESULTS

During the study 384 heart and 194 lung transplants were performed. Twenty-one (5.5%) heart and six (3.1%) lung recipients developed candidemia. Heart recipients with candidemia were more likely to have had delayed chest closure (38.1% vs. 0%, p < .0001), temporary mechanical circulatory support (57.1% vs. 11.9%, p = .0003), and repeat surgical chest exploration 76.2% vs. 16.7%, p < .0001) than uninfected controls. Heart and lung recipients who developed candidemia were more likely to have been on renal replacement therapy prior to infection relative to uninfected controls (57.1% vs. 11.9%, p = .0003 and 66.7% vs. 0%, p = .0041, respectively). Heart recipients with candidemia had significantly lower post-transplant survival and lower post-infection survival relative to matched uninfected controls and heart recipients with bacteremia, respectively (p < .0001 and p = .0002, respectively).

CONCLUSIONS

Candidemia following heart and lung transplantation is associated with significant morbidity and mortality. Further research is needed to understand if heart recipients with delayed chest closure, temporary mechanical circulatory support, renal replacement therapy, and repeat surgical chest exploration may benefit from targeted antifungal prophylaxis.

Risk Factors and Outcome of Gram-Negative Bloodstream Infection in Living-Donor Renal Transplant Recipients: A Case-Control Study From Pakistan

OBJECTIVES

Gram-negative rods are the most common cause of bloodstream infection in renal transplant recipients. Acute rejection, urologic abnormalities, and ureteral stents are risk factors. Graft dysfunction is independently associated with gram-negative rod bloodstream infection. Our aim is to investigate the incidence, risk factors, and outcome among living donor renal transplant recipients from Pakistan.

MATERIALS AND METHODS

In this case-control study, we reviewed the medical records until June 2021 of renal transplant recipients seen from 2015 to 2019 for gram negative bacteremia. For every case, controls were matched by age, date of transplant, and sex. Demographics, risk factors, graft function, and mortality were compared. Clinical features, immunosuppression, source of blood stream infection, and microbiology were noted in cases.

RESULTS

Of 1677 renal transplant recipients, 44 developed gram negative bacteremia. The incidence was 5.9 per 1000 person-years. Median time since transplant was 5 months. The most common source was urinary tract infection. On univariate analysis, antithymocyte globulin, urinary tract infection, and recurrent urinary tract infections were associated with gram negative bacteremia. On multivariate analysis, urinary tract infection (adjusted odds ratio = 3.46; 95% CI, 1.27-9.37) and recurrent urinary tract infections (adjusted odds ratio = 4.03; 95% CI, 1.15-14.15) were significant risk factors. We found no difference in 30-day mortality and estimated glomerular filtration rate on last follow-up between cases and controls. Kaplan-Meier survival curves showed significant differences in graft survival in patients with gram negative bacteremia. Escherichia coli was the most common organism, with 75% ceftriaxone and 13% imipenem resistance.

CONCLUSIONS

The most significant risk factor for gram negative rod bloodstream infection was recurrent urinary tract infections. Timely treatment and prevention of recurrent urinary tract infections areimperative for prevention of gram negative bacteremia.

Epidemiology and Prevention of Early Infections by Multi-Drug-Resistant Organisms in Adults Undergoing Liver Transplant: A Narrative Review

Invasive bacterial infections are a leading cause of morbidity and mortality after liver transplant (LT), especially during the first months after LT, and infections due to multi-drug-resistant organisms (MDRO) are increasing in this setting. Most of the infections in patients in intensive care unit arise from the endogenous microflora and, for this reason, pre-LT MDRO rectal colonization is a risk factor for developing MDRO infections in the post-LT. Moreover, the transplanted liver may carry an increased risk of MDRO infections due to organ transportation and preservation, to donor intensive care unit stay and previous antibiotic exposure. To date, little evidence is available about how MDRO pre-LT colonization in donors and recipients should address LT preventive and antibiotic prophylactic strategies, in order to reduce MDRO infections in the post-LT period. The present review provided an extensive overview of the recent literature on these topics, with the aim to offer a comprehensive insight about the epidemiology of MDRO colonization and infections in adult LT recipients, donor-derived MDRO infections, possible surveillance, and prophylactic strategies to reduce post-LT MDRO infections.

Bacteremia During the First Year After Solid Organ Transplantation: An Epidemiological Update

Background

There are limited contemporary data on the epidemiology and outcomes of bacteremia in solid organ transplant recipients (SOTr).

Methods

Using the Swiss Transplant Cohort Study registry from 2008 to 2019, we performed a retrospective nested multicenter cohort study to describe the epidemiology of bacteremia in SOTr during the first year post-transplant.

Results

Of 4383 patients, 415 (9.5%) with 557 cases of bacteremia due to 627 pathogens were identified. One-year incidence was 9.5%, 12.8%, 11.4%, 9.8%, 8.3%, and 5.9% for all, heart, liver, lung, kidney, and kidney-pancreas SOTr, respectively (P = .003). Incidence decreased during the study period (hazard ratio, 0.66; P < .001). One-year incidence due to gram-negative bacilli (GNB), gram-positive cocci (GPC), and gram-positive bacilli (GPB) was 5.62%, 2.81%, and 0.23%, respectively. Seven (of 28, 25%) Staphylococcus aureus isolates were methicillin-resistant, 2/67 (3%) enterococci were vancomycin-resistant, and 32/250 (12.8%) GNB produced extended-spectrum beta-lactamases. Risk factors for bacteremia within 1 year post-transplant included age, diabetes, cardiopulmonary diseases, surgical/medical post-transplant complications, rejection, and fungal infections. Predictors for bacteremia during the first 30 days post-transplant included surgical post-transplant complications, rejection, deceased donor, and liver and lung transplantation. Transplantation in 2014-2019, CMV donor-negative/recipient-negative serology, and cotrimoxazole Pneumocystis prophylaxis were protective against bacteremia. Thirty-day mortality in SOTr with bacteremia was 3% and did not differ by SOT type.

Conclusions

Almost 1/10 SOTr may develop bacteremia during the first year post-transplant associated with low mortality. Lower bacteremia rates have been observed since 2014 and in patients receiving cotrimoxazole prophylaxis. Variabilities in incidence, timing, and pathogen of bacteremia across different SOT types may be used to tailor prophylactic and clinical approaches.

Clinical characteristics, risk factors and outcomes of Klebsiella pneumoniae pneumonia developing secondary Klebsiella pneumoniae bloodstream infection

Purpose

The clinical characteristics of Klebsiella pneumoniae (KP) pneumonia and KP bloodstream infection (KP-BSI) are often reported, while the risk factors for KP pneumonia developing into secondary KP-BSI (KP-pneumonia/KP-BSI) are largely unknown. Therefore, this study attempted to investigate the clinical characteristics, risk factors and outcomes of KP-pneumonia/KP-BSI.

Methods

A retrospective observational study was conducted at a tertiary hospital between January 1, 2018, and December 31, 2020. The patients were divided into groups of KP pneumonia alone and KP pneumonia/KP-BSI, and the clinical information were collected from medical records electronic system.

Results

A total of 409 patients were finally recruited. According to the multivariate logistic regression analysis, male sex (adjusted odds ratio [aOR] 3.7; 95% CI, 1.44–9.5), immunosuppression (aOR, 13.52; 95% CI, 2.53,72.22), APACHE II score higher than 21 (aOR, 3.39; 95% CI, 1.41–8.12), serum procalcitonin (PCT) levels above 1.8 ng/ml (aOR, 6.37; 95% CI, 2.67–15.27), ICU stay of more than 2.5 days before pneumonia onset (aOR, 1.09; 95% CI, 1.02,1.17), mechanical ventilation (aOR, 4.96; 95% CI, 1.2,20.5), Klebsiella pneumoniae isolates producing extended spectrum β-lactamase (ESBL-positive KP) (aOR, 12.93; 95% CI, 5.26–31.76), and inappropriate antibacterial therapy (aOR, 12.38; 95% CI, 5.36–28.58) were independent factors of KP pneumonia/KP BSI. In comparison with the patients with KP pneumonia alone, the patients with KP pneumonia/KP BSI showed an almost 3 times higher incidence of septic shock (64.4% vs. 20.1%, p < 0.01), a longer duration of mechanical ventilation, and longer lengths of ICU stay and total hospital stay (median days, 15 vs. 4,19 vs. 6, 34 vs. 17, respectively, both p < 0.01). Additionally, the overall in-hospital crude mortality rate in the patients with KP-pneumonia/KP-BSI was more than two times higher than that in those with KP pneumonia alone (61.5% vs. 27.4%, p < 0.01).

Conclusion

Factors including male sex, immunosuppression, APACHE II score higher than 21, serum PCT levels above 1.8 ng/ml, ICU stay of more than 2.5 days before pneumonia onset, mechanical ventilation, ESBL-positive KP, and inappropriate antibacterial therapy are independent risk factors for KP pneumonia/KP-BSI. Of note, the outcomes in patients with KP pneumonia worsen once they develop secondary KP-BSI, which merits more attention.

Pseudomonas aeruginosa: Infections, Animal Modeling, and Therapeutics

Pseudomonas aeruginosa is an important Gram-negative opportunistic pathogen which causes many severe acute and chronic infections with high morbidity, and mortality rates as high as 40%. What makes P. aeruginosa a particularly challenging pathogen is its high intrinsic and acquired resistance to many of the available antibiotics. In this review, we review the important acute and chronic infections caused by this pathogen. We next discuss various animal models which have been developed to evaluate P. aeruginosa pathogenesis and assess therapeutics against this pathogen. Next, we review current treatments (antibiotics and vaccines) and provide an overview of their efficacies and their limitations. Finally, we highlight exciting literature on novel antibiotic-free strategies to control P. aeruginosa infections.

Epidemiology and outcomes of bone and joint infections in solid organ transplant recipients

Bone and joint infection (BJI) epidemiology and outcomes in solid organ transplant recipients (SOTr) remain largely unknown. We aim to describe BJI in a multi-center cohort of SOTr (Swiss Transplant Cohort Study). All consecutive SOTr with BJI (01.05.2008-31.12.2019) were included. A nested case-control study to identify risk factors for BJI was performed. Among 4482 patients, 61 SOTr with 82 BJI were included, at an incidence of 1.4% (95% CI 1.1-1.7), higher in heart and kidney-pancreas SOTr (Gray's test p < .01). Although BJI were predominately late events (median of 18.5 months post-SOT), most infections occurred during the first year post-transplant in thoracic SOTr. Diabetic foot osteomyelitis was the most frequent infection (38/82, 46.3%), followed by non-vertebral osteomyelitis (26/82, 31.7%). Pathogens included Gram-positive cocci (70/131, 53.4%), Gram-negative bacilli (34/131, 26.0%), and fungi (9/131, 6.9%). BJI predictors included male gender (OR 2.94, 95% CI 1.26-6.89) and diabetes (OR 2.97, 95% CI 1.34-6.56). Treatment failure was observed in 25.9% (21/81) patients and 1-year mortality post-BJI diagnosis was 14.8% (9/61). BJI remain a rare event in SOTr, associated with subtle clinical presentations, high morbidity and relapses, requiring additional studies in the future.

Bacteraemia Is Associated with Increased ICU Mortality in the Postoperative Course of Lung Transplantation

We aimed to describe the prevalence, risk factors, morbidity and mortality associated with the occurrence of bacteraemia during the postoperative ICU stay after lung transplantation (LT). We conducted a retrospective single-centre study that included all consecutive patients who underwent LT between January 2015 and October 2021. We analysed all the blood cultures drawn during the postoperative ICU stay, as well as samples from suspected infectious sources in case of bacteraemia. Forty-six bacteria were isolated from 45 bacteraemic patients in 33/303 (10.9%) patients during the postoperative ICU stay. Staphylococcus aureus (17.8%) was the most frequent bacteria, followed by Pseudomonas aeruginosa (15.6%) and Enterococcus faecium (15.6%). Multidrug-resistant bacteria accounted for 8/46 (17.8%) of the isolates. The most common source of bacteraemia was pneumonia (38.3%). No pre- or intraoperative risk factor for bacteraemia was identified. Recipients who experienced bacteraemia required more renal replacement therapy, invasive mechanical ventilation, norepinephrine support, tracheotomy and more days of hospitalization during the ICU stay. After adjustment for age, sex, type of LT procedure and the need for intraoperative ECMO, the occurrence of bacteraemia was associated with a higher mortality rate in the ICU (aOR = 3.55, 95% CI [1.56–8.08], p = 0.003). Bacteraemia is a major source of concern for lung transplant recipients.

Population pharmacokinetic analysis, renal safety, and dosing optimization of polymyxin B in lung transplant recipients with pneumonia: A prospective study

Objectives: This study aims to characterize the population pharmacokinetics of polymyxin B in lung transplant recipients and optimize its dosage regimens.

Patients and methods: This prospective study involved carbapenem-resistant organisms-infected patients treated with polymyxin B. The population pharmacokinetic model was developed using the NONMEM program. The clinical outcomes including clinical treatment efficacy, microbiological efficacy, nephrotoxicity, and hyperpigmentation were assessed. Monte Carlo simulation was performed to calculate the probability of target attainment in patients with normal or decreased renal function.

Results: A total of 34 hospitalized adult patients were included. 29 (85.29%) patients were considered of clinical cure or improvement; 14 (41.18%) patients had successful bacteria elimination at the end of the treatment. Meanwhile, 5 (14.71%) patients developed polymyxin B-induced nephrotoxicity; 19 (55.88%) patients developed skin hyperpigmentation. A total of 164 concentrations with a range of 0.56–11.66 mg/L were obtained for pharmacokinetic modeling. The pharmacokinetic characteristic of polymyxin B was well described by a 1-compartment model with linear elimination, and only creatinine clearance was identified as a covariate on the clearance of polymyxin B. Monte Carlo simulations indicated an adjusted dosage regimen might be needed in patients with renal insufficiency and the currently recommended dose regimens by the label sheet of polymyxin B may likely generate a subtherapeutic exposure for MIC = 2 mg/L.

Conclusion: Renal function has a significant effect on the clearance of polymyxin B in lung transplant recipients, and an adjustment of dosage was needed in patients with renal impairments.

Surgical Site Infections in Post-Living Donor Liver Transplantation: Surveillance and Evaluation of Care Bundle Approach

Background and Aim: Although implantation of a care bundle approach is well established in intensive care units (ICUs), yet its impact on reducing surgical site infections (SSI) among post living-donor-liver transplantation (LDLT) patients has not been established. Our aim is to evaluate the impact of a care bundle in reducing SSI and to detect the pattern of antibiotic resistance in LDLT. Materials and Methods: This before and after comparative study was conducted at Elmanial specialized tertiary hospital, Cairo University over a period of 3 years (January 2016 - December 2018) including 57 LDLT patients. We introduced a care bundle comprised of a group of evidence-based practices implemented together. The study was divided into three phases. All bacterial identification and antibiotic sensitivity testing were done by a Vitek 2 compact system. Results: SSIs rates were reduced significantly by 30.4% from the pre-implementation to the post implementation phase (from 13/24, 54.2% to 5/21, 23.8%, OR 0.21, CI 95%: 1.137- 0.039). This reduction went hand in hand with increase in the hand hygiene compliance from 57.3 % to 78 %, then remained sustained with a median rate of 78% in the last 6 months. Klebsiella pneumoniae 11\25 (44% of SSIs), Acinetobacter baumannii 8\25 (32% of SSIs), Escherichia coli 5\25 (20%), Pseudomonas aeruginosa 5\25 (20%) and MRSA 4\25 (16%). With predominance of XDR phenotype 14/25 (56%), followed by ESBL of gram-negative bacteria 6/25 (24%), then MRSA 4/25 (16%). Conclusion: SSIs in LDLT mandates strict implementation of comprehensive evidence-based care bundles for better patent outcome.

Sepsis affects kidney graft function and one-year mortality of the recipients in contrast with systemic inflammatory response

Background

Infections remain a major cause of morbidity and mortality after kidney transplantation. The aim of our study was to determine the effect of sepsis on kidney graft function and recipient mortality.

Methods

A prospective, observational, single-center study was performed. Selected clinical and biochemical parameters were recorded and compared between an experimental group (with sepsis, n = 34) and a control group (with systemic inflammatory response syndrome, n = 31) comprising kidney allograft recipients.

Results

Sepsis worsened both patient (HR = 14.77, p = 0.007) and graft survival (HR = 15.07, p = 0.007). Overall one-year mortality was associated with age (HR = 1.08, p = 0.048), APACHE II score (HR = 1.13, p = 0.035), and combination immunosuppression therapy (HR = 0.1, p = 0.006), while graft survival was associated with APACHE II (HR = 1.25, p = 0.004) and immunosuppression. In sepsis patients, mortality correlated with the maximal dose of noradrenalin (HR = 100.96, p = 0.008), fungal infection (HR = 5.64, p = 0.024), SAPS II score (HR = 1.06, p = 0.033), and mechanical ventilation (HR = 5.97, p = 0.033), while graft survival was influenced by renal replacement therapy (HR = 21.16, p = 0.005), APACHE II (HR = 1.19, p = 0.035), and duration of mechanical ventilation (HR = 1.01, p = 0.015).

Conclusion

In contrast with systemic inflammatory response syndrome, septic kidney allograft injury is associated with early graft loss and may represent a significant risk of mortality.

Acute kidney injury secondary to urinary tract infection in kidney transplant recipients

Acute kidney injury (AKI) in kidney transplant recipients (KTRs) is a common, yet poorly investigated, complication of urinary tract infections (UTI) and urosepsis. A retrospective comparative analysis was performed, recruiting 101 KTRs with urosepsis, 100 KTRs with UTI, and 100 KTRs without history of UTI or sepsis. The incidences of AKI in the urosepsis and UTI groups were 75.2% and 41%, respectively. The urosepsis group has also presented with a significantly higher prevalence of AKI stage 2 and 3 than the UTI group. The rates of recovery from AKI stages 1, 2 and 3, were 75,6%, 55% and 26.1%, respectively. Factors independently associated with renal recovery from AKI were: AKI severity grade (AKI stage 2 with OR = 0.25 and AKI stage 3 with OR = 0.1), transfusion of red blood cells (RBC) (OR = 0.22), and the use of steroid bolus in the acute phase of treatment (OR = 4). The septic status (urosepsis vs UTI) did not influence the rates of renal recovery from AKI after adjustment for the remaining variables. The dominant cause of RBC transfusions in the whole population was upper GI-bleeding. In multivariable analyses, the occurrence of AKI was also independently associated with a greater decline of eGFR at 1-year post-discharge and with a greater risk of graft loss. In KTRs with both urosepsis and UTI, the occurrence of AKI portends poor transplantation outcomes. The local transfusion policy, modulation of immunosuppression and stress ulcer prophylaxis (which is not routinely administered in KTRs) in the acute setting may be modifiable factors that significantly impact long-term transplantation outcomes.

Incidences of infectious events in a renal transplant cohort of the German Center of Infectious Diseases (DZIF)

Background

Infectious complications are a major cause of morbidity and mortality after kidney transplantation.

Methods

In this transplant cohort study at the German Center of Infectious Diseases (DZIF), we evaluated all infections occurring during the first year after renal transplantation. We assessed microbial etiology, incidence rates, and temporal occurrence of these infections.

Results

Of 804 renal transplant recipients (65.2% male, 51 ± 14 years), 439 (54.6%) had 972 infections within the first year after transplantation. Almost half of these infections (47.8%) occurred within the first three months. Bacteria were responsible for 66.4% (645/972) of all infections, followed by viral (28.9%[281/972]) and fungal (4.7%[46/972]) pathogens. The urinary tract was the most common site of infection (42.4%). Enterococcus was most frequently isolated bacteria (20.9%), followed by E.coli (17.6%) and Klebsiella (12.5%). E.coli was the leading pathogen in recipients &lt;50 years of age, whereas Enterococcus predominated in older recipients. Resistant bacteria were responsible for at least one infection in 9.5% (76/804) of all recipients. Viral infections occurred in 201 recipients (25.0%). Of these, herpes viruses predominated (140/281[49.8%]) and cytomegalovirus had the highest incidence rate (12.3%). In the 46 fungal infections, Candida albicans (40.8%) was most commonly isolated. Other fungal opportunistic pathogens, including Aspergillus fumigatus and Pneumocystis, were rare.

Conclusions

Renal allograft recipients in Germany experience a high burden of infectious complications in the first year after transplantation. Bacteria were the predominating pathogen, followed by opportunistic infections such as cytomegalovirus. Microbial etiology varied between age groups and resistant bacteria were identified in 10% of recipients.

The long-term impact of bloodstream infections on patient and graft survival following kidney transplantation

BACKGROUND

There are limited data on the impact of bloodstream infections (BSI) following kidney transplantation (KT) on long term patient outcome.

METHODS

This was a retrospective parallel-cohort study. We included 123 consecutive KT recipients who were admitted with a first episode of BSI between 1/2007-12/2016. They were matched with 225 KT recipients who did not have BSI. Multivariate regression analysis with BSI as time-dependent covariate was used for the effect of BSI on graft loss, all-cause mortality and long-term graft function (defined by the slope of mean serum creatinine level).

RESULTS

During a median follow-up of 89.4 months, post-transplant BSI was independently associated with all-cause mortality (HR 5.56, 95% CI 3.07-10.09, p<0.0001) and graft failure (HR-2.82, 95% CI 1.40-5.64, p = 0.003) after adjustment for potential confounders. This association remained irrespective of the source of infection or pathogen, but became non-significant when appropriate antibiotic therapy was administrated. Baseline kidney function was independently associated with graft failure. Recipients with BSI had lower baseline kidney function, however the BSI episode had no influence on the slope of change in serum creatinine over time.

CONCLUSION

BSI after KT was associated with long-term adverse outcome. This effect was mitigated by the early administration of appropriate antibiotics. This article is protected by copyright. All rights reserved.

Multidrug-resistant infections in solid organ transplant recipients: a focus on risk factors, prevention and treatment strategies

Solid organ transplantation is the best therapeutic option for patients with end-stage organ disease and, according to the data from international registries, there has been a steady increase in numbers and results. However, post-transplant infections remain a fearsome complication with, in the last decade, an increasing incidence of episodes due to antibiotic-resistant bacteria and opportunistic agents. In this paper, we summarize the most relevant and updated knowledge concerning infections from multidrug-resistant germs in solid organ transplant recipients, focusing on risk factors, treatment and prevention strategies, and antimicrobial pharmacokinetics relevant to this particular population of patients.

Bacterial and Viral Infection and Sepsis in Kidney Transplanted Patients

Kidney transplanted patients are a unique population with intrinsic susceptibility to viral and bacterial infections, mainly (but not exclusively) due to continuous immunosuppression. In this setting, infectious episodes remain among the most important causes of death, with different risks according to the degree of immunosuppression, time after transplantation, type of infection, and patient conditions. Prevention, early diagnosis, and appropriate therapy are the goals of infective management, taking into account that some specific characteristics of transplanted patients may cause a delay (the absence of fever or inflammatory symptoms, the negativity of serological tests commonly adopted for the general population, or the atypical anatomical presentation depending on the surgical site and graft implantation). This review considers the recent available findings of the most common viral and bacterial infection in kidney transplanted patients and explores risk factors and outcomes in septic evolution.

Distribution and Antibiotic Susceptibility Pattern of Multidrug-Resistant Bacteria and Risk Factors Among Kidney Transplantation Recipients with Infections Over 13 Years: A Retrospective Study

Background

Infection ranks as the most common complication after kidney transplantation (KT) and threatens outcomes of kidney transplantation recipients (KTR). This study aimed to investigate the microbiological profile of infection, assess bacterial resistance and identify risk factors for multidrug-resistant (MDR) bacterial infection among KTR.

Methods

During the study period, 866 recipients underwent kidney transplant surgery. We studied the distribution of pathogens, resistance rate of MDR bacteria and the risk factors of MDR bacterial infection.

Results

Totally, 214 species of pathogens (110 species were MDR bacteria) were isolated in 119 KTR. Escherichia coli (E. coli) was the most common bacteria of the infection. MDR extended spectrum β-lactamase (ESBL)-producing Enterobacteriaceae (ESBL-E) were most resistant to ampicillin, cefazolin, ciprofloxacin and complex sulfamethoxazole, while quite sensitive to imipenem, amikacin and piperacillin/tazobactam (PIT). All MDR gram-positive bacteria were quite sensitive to linezolid and vancomycin, except that MDR Staphylococcus was also susceptible to rifampicin. Female gender (OR = 3.497, 95% CI = 1.445–8.467, P = 0.006), pathogen types > 1 (OR = 3.832, 95% CI = 1.429–10.273, P = 0.008) and postoperative time < 3 months (OR = 0.331, 95% CI = 0.137–0.799, P = 0.014) were independent risk factors for MDR bacterial infection.

Conclusion

PIT and amikacin may be an alternative choice of ESBL-E infection. Rifampicin can also be prescribed for MDR Staphylococcus infection. MDR bacterial infection was associated with female gender, pathogen types more than 1 and 3 months postoperative period.

Incidencia de infecciones en el postrasplante renal inmediato

Introducción: El receptor de un trasplante renal es un paciente de alto riesgo para sufrir infección debido a las potenciales complicaciones quirúrgicas y al tratamiento inmunosupresor que reciben.El desarrollo de infecciones supone un riesgo aumentado de pérdida del injerto y de la mortalidad. Objetivos: El objetivo principal fue conocer la incidencia de las infecciones más frecuentes en el paciente con un trasplante renal, durante el periodo postrasplante inmediato.Los objetivos secundarios fueron describir los gérmenes responsables de las infecciones más frecuentes y analizar la relación entre los tipos de infección estudiados y sus posibles factores de riesgo. Metodología: Estudio observacional retrospectivo en pacientes trasplantados renales entre enero de 2018 y diciembre de 2019 durante el periodo del postrasplante inmediato.Resultados: La incidencia de infección fue 69,4%, los síndromes descritos fueron infección del tracto urinario (48%), bacteriemia (9,2%), infección relacionada con catéter (8,2%) e infección por citomegalovirus (4,1%). Los microorganimos más frecuentemente implicados, en estos procesos infecciosos fueron Escherichia coli (16,3%), Enterococus faecium (12,2%) y Enterobacter cloacae (8,1%).Se ha encontrado relación significativa entre la aparición de infección y la duración del ingreso, así como con la presencia o no del antecedente personal de hipertensión arterial. También entre la incidencia de infección relacionada con el catéter venoso central y el tiempo que permaneció insertado. Conclusiones: La infección más frecuente encontrada en el postrasplante renal inmediato fue la infección del tracto urinario, mientras que el microorganismo más presente habitualmente en los procesos infecciosos fue la Escherichia coli.

Recommendations of the Italian society for infectious and tropical diseases (SIMIT) for adult vaccinations

Vaccination prevents 2-3 million deaths worldwide every year. Nevertheless, vaccine-preventable diseases (VPDs) still cause a considerable number of deaths especially in subjects belonging to "risk groups." These are represented by older adults, immunocompromised individuals and all subjects with underlying chronic medical conditions (cardiovascular, pulmonary, renal and liver chronic diseases, diabetes, immunodeficiency disorders). They have a weaker immune system and, if infected, are more likely to develop severe complications of their condition or of the preventable-infectious disease. This document summarizes the recommendations for vaccination of the main Global Institutional Organizations and analyses the risks of comorbidities associated with infectious disease and the benefits of vaccination for each specific group. The document provides a clear, practical and authoritative guide to adult vaccination.

Burden of pneumococcal disease among adults in Southern Europe (Spain, Portugal, Italy, and Greece): a systematic review and meta-analysis

The aim was to summarize pneumococcal disease burden data among adults in Southern Europe and the potential impact of vaccines on epidemiology. Of 4779 identified studies, 272 were selected. Invasive pneumococcal disease (IPD) incidence was 15.08 (95% CI 11.01-20.65) in Spain versus 2.56 (95% CI 1.54-4.24) per 100,000 population in Italy. Pneumococcal pneumonia incidence was 19.59 (95% CI 10.74-35.74) in Spain versus 2.19 (95% CI 1.36-3.54) per 100,000 population in Italy. Analysis of IPD incidence in Spain comparing pre-and post- PCV7 and PCV13 periods unveiled a declining trend in vaccine-type IPD incidence (larger and statistically significant for the elderly), suggesting indirect effects of childhood vaccination programme. Data from Portugal, Greece and, to a lesser extent, Italy were sparse, thus improved surveillance is needed. Pneumococcal vaccination uptake, particularly among the elderly and adults with chronic and immunosuppressing conditions, should be improved, including shift to a higher-valency pneumococcal conjugate vaccine when available.

Survival Outcome of Sepsis in Recipients of Solid Organ Transplant

Sepsis is a complex disease stemming from a dysregulated immune response toward an infectious agent. In transplantation, sepsis remains one of the leading causes of morbidity and mortality. Solid organ transplant recipients have impaired adaptive immunity due to immunosuppression required to prevent rejection. Immunosuppression has unintended consequences, such as increasing the risk of infections and sepsis. Due to its high morbidity and mortality, early detection of sepsis is paramount to start aggressive treatment. Several biomarkers or combination of biomarkers of sepsis have emerged in the last decade, but they are not dependable for early diagnosis or for outcome prognosis.

New drugs for difficult bugs: management of multidrug-resistant gram-negative infections in solid organ transplant recipients

PURPOSE OF REVIEW

Multidrug-resistant Gram-negative bacteria remain a significant threat to patient and allograft survival. Management of these infections in solid organ transplant (SOT) recipients remains challenging due to a limited antimicrobial pipeline and reliance on novel agents, which have not been systematically evaluated in the transplant population.

RECENT FINDINGS

Novel antimicrobials, including the second-generation β-lactam/β-lactamase inhibitors, cefiderocol, plazomicin and eravacycline, have been developed to combat infections due to multidrug-resistant Gram-negative infections, but each has microbiologic and therapeutic niches and warrant further study in SOT recipients.

SUMMARY

This review summarizes therapeutic options for extended-spectrum β-lactamase-producing Enterobacterales, carbapenem-resistant Enterobacterales and Pseudomonas aeruginosa with difficult-to-treat resistance in SOT recipients and emphasizes recently approved antimicrobial agents.

Bacterial and fungal bloodstream infections in solid organ transplant recipients: results from a Danish cohort with nationwide follow-up

OBJECTIVES

Bloodstream infections (BSI) are prevalent after solid organ transplantation (SOT). In this study, we aimed to investigate the incidence and risk factors for BSI in the first 5 years post-transplantation.

METHODS

The study included 1322 SOT (kidney, liver, lung and heart) recipients transplanted from 2010 to 2017 with a total of 5616 years of follow-up. Clinical characteristics and microbiology were obtained from the Centre of Excellence for Personalized Medicine of Infectious Complications in Immune Deficiency (PERSIMUNE) data repository with nationwide follow-up. Incidence was investigated in the different SOT groups. Risk factors associated with BSI were assed in the combined group in time-updated multivariable Cox regressions.

RESULTS

The cumulative incidence of first BSI in the first 5 years post-transplantation differed in the SOT groups with a lower incidence in heart transplant recipients than in the other SOT groups (heart: 4.4%, CI 0.0-9.7%, vs. kidney: 24.6%, CI 20.9-28.2%, liver: 24.7%, CI 19.4-29.9%, and lung: 19.6%, CI 14.5-24.8%, p <0.001). Age above 55 years (HR 1.71, CI 1.2-2.4, p=0.002) and higher Charlson comorbidity index score (HR per unit increase: 1.25, CI 1.1-1.4, p<0.001) at transplantation, current cytomegalovirus (CMV) infection (HR 4.5, CI 2.6-7.9, p<0.001) and current leucopenia (HR 13.3, CI 3.7-47.9, p<0.001) were all associated with an increased risk of BSI.

CONCLUSION

In SOT recipients, the incidence of BSI differed with the type of transplanted organ. Risk of BSI was higher in older recipients and in recipients with comorbidity, current CMV infection or leucopenia. Thus, increased attention towards BSI in recipients with these characteristics is warranted.

Bacterial and fungal bloodstream infections in pediatric liver and kidney transplant recipients

Background

Bacterial and fungal bloodstream infections (BSI) are common after pediatric liver and kidney transplantations and associated with morbidity and mortality. However, knowledge about incidence rates, pathogen composition, and resistance patterns is limited. We aimed to describe the pattern of bacterial and fungal BSI in a cohort of pediatric liver and kidney transplant recipients.

Methods

A prospective study of 85 pediatric liver and kidney transplant recipients transplanted from 2010 to 2017 with a total of 390 person-years of follow-up. Clinical characteristics and BSI were retrieved from national registries assuring nationwide follow-up for at least 1 year. BSI incidence rates and pathogen composition were investigated and stratified by the time post-transplantation and type of transplanted organ.

Results

A total of 29 BSI were observed within the first 5 years post-transplantation with 16 different pathogens. The overall incidence rate of first BSI was 1.91 per 100 recipients per month (95% CI, 1.1–3.1) in the first year post-transplantation. The most common pathogens were Enterococcus faecium, Candida albicans, Escherichia coli, and Klebsiella pneumoniae. The pathogen composition depended on the transplanted organ with a higher proportion of BSI with Enterobacterales in kidney transplant recipients than in liver transplant recipients (67% vs. 20%, p = 0.03), while multiple pathogens were detected in the liver transplant recipients.

Conclusions

BSI were common in pediatric liver and kidney transplant recipients and the pathogen composition differed between liver and kidney transplant recipients. Guidelines for empiric antibiotic therapy should consider the type of transplanted organ as well as the local resistance patterns.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-06224-2.

Molecular characterization of multidrug resistant Enterobacterales strains isolated from liver and kidney transplant recipients in Spain

The objective of this study was to analyse the mechanisms of resistance to carbapenems and other extended-spectrum-β-lactams and to determine the genetic relatedness of multidrug-resistant Enterobacterales (MDR-E) causing colonization or infection in solid-organ transplantation (SOT) recipients. Prospective cohort study in kidney (n = 142), liver (n = 98) or kidney/pancreas (n = 7) transplant recipients between 2014 and 2018 in seven Spanish hospitals. We included 531 MDR-E isolates from rectal swabs obtained before transplantation and weekly for 4–6 weeks after the procedure and 10 MDR-E from clinical samples related to an infection. Overall, 46.2% Escherichia coli, 35.3% Klebsiella pneumoniae, 6.5% Enterobacter cloacae, 6.3% Citrobacter freundii and 5.7% other species were isolated. The number of patients with MDR-E colonization post-transplantation (176; 71.3%) was 2.5-fold the number of patients colonized pre-transplantation (71; 28.7%). Extended-spectrum β-lactamases (ESBLs) and carbapenemases were detected in 78.0% and 21.1% of MDR-E isolates respectively. In nine of the 247 (3.6%) transplant patients, the microorganism causing an infection was the same strain previously cultured from surveillance rectal swabs. In our study we have observed a low rate of MDR-E infection in colonized patients 4–6 weeks post-transplantation. E. coli producing bla_CTX-M-G1 and K. pneumoniae harbouring bla_OXA-48 alone or with bla_CTX-M-G1 were the most prevalent MDR-E colonization strains in SOT recipients.

Antibiotic-Resistant Infections and Treatment Challenges in the Immunocompromised Host: An Update

This article reviews antibiotic resistance and treatment of bacterial infections in the growing number of patients who are immunocompromised: solid organ transplant recipients, the neutropenic host, and persons with human immunodeficiency virus and AIDS. Specific mechanisms of resistance in both gram-negative and gram-positive bacteria, as well as newer treatment options are addressed elsewhere and are only briefly discussed in the context of the immunocompromised host.

Burden and Timeline of Infectious Diseases in the First Year After Solid Organ Transplantation in the Swiss Transplant Cohort Study

Background

The burden and timeline of posttransplant infections are not comprehensively documented in the current era of immunosuppression and prophylaxis.

Methods

In this prospective study nested within the Swiss Transplant Cohort Study (STCS), all clinically relevant infections were identified by transplant–infectious diseases physicians in persons receiving solid organ transplant (SOT) between May 2008 and December 2014 with ≥12 months of follow-up.

Results

Among 3541 SOT recipients, 2761 (1612 kidney, 577 liver, 286 lung, 213 heart, and 73 kidney-pancreas) had ≥12 months of follow-up; 1520 patients (55%) suffered 3520 infections during the first year posttransplantation. Burden and timelines of clinically relevant infections differed between transplantations. Bacteria were responsible for 2202 infections (63%) prevailing throughout the year, with a predominance of Enterobacteriaceae (54%) as urinary pathogens in heart, lung, and kidney transplant recipients, and as digestive tract pathogens in liver transplant recipients. Enterococcus spp (20%) occurred as urinary tract pathogens in kidney transplant recipients and as digestive tract pathogens in liver transplant recipients, and Pseudomonas aeruginosa (9%) in lung transplant recipients. Among 1039 viral infections, herpesviruses predominated (51%) in kidney, liver, and heart transplant recipients. Among 263 fungal infections, Candida spp (60%) prevailed as digestive tract pathogens in liver transplant recipients. Opportunistic pathogens, including Aspergillus fumigatus (1.4%) and cytomegalovirus (6%), were rare, scattering over 12 months across all SOT recipients.

Conclusions

In the current era of immunosuppression and prophylaxis, SOT recipients experience a high burden of infections throughout the first year posttransplantation, with rare opportunistic pathogens and a predominance of bacteria.

Risk Factors for Mortality in Hematopoietic Stem Cell Transplantation Recipients with Bloodstream Infection: Points To Be Addressed by Future Guidelines

In recent years, important epidemiologic changes have been described in hematopoietic stem cell transplantation (HSCT) recipients with bloodstream infection (BSI), with increases in gram-negative bacilli and multidrug resistant (MDR) gram-negative bacilli. These changes have been linked to a worrisome increase in mortality. We aimed to define the risk factors for mortality of HSCT patients experiencing BSI. All episodes of BSI in patients with HSCT between 2008 and 2017 were prospectively collected. Multivariate analyses were performed. A total of 402 BSI episodes were documented in 293 patients who had undergone HSCT (75.4% allogenic, 32.3% autologous, 19.3% second HSCT). The median time from HSCT to BSI was 62 days (interquartile range, 9 to 182 days). Gram-positive cocci accounted for 56.7% of the episodes; gram-negative bacilli, for 42%. The most common microorganisms were coagulase-negative staphylococci (30.6%) and Pseudomonas aeruginosa (15.9%). MDR gram-negative bacilli caused 11.9% of all episodes. Clinical characteristics, source of BSI, etiology, and outcomes changed depending on time since HSCT. Globally, 26.6% of episodes were treated with inappropriate empiric antibiotic therapy, more frequently in BSI episodes caused by P. aeruginosa, MDR P. aeruginosa, and MDR gram-negative bacilli. The 30-day mortality was 19.2%. Independent risk factors for mortality were BSI occurring ≥30 days after HSCT (odds ratio [OR], 11.21; 95% confidence interval [CI], 4.63 to 27.19), shock (OR, 7.10; 95% CI, 2.98 to 16.94), BSI caused by MDR P. aeruginosa (OR, 4.45; 95% CI, 1.12 to 17.72), and inappropriate empiric antibiotic therapy for gram-negative bacilli or Candida spp. (OR, 3.73; 95% CI, 1.27 to 10.89). HSCT recipients experiencing BSI have high mortality related to host and procedure factors, causative microorganism, and empiric antibiotic therapy. Strategies to identify HSCT recipients at risk of MDR P. aeruginosa and reducing inappropriate empiric antibiotic therapy are paramount to reduce mortality.

Efficacy of β-lactam/β-lactamase inhibitors to treat extended-spectrum beta-lactamase-producing Enterobacterales bacteremia secondary to urinary tract infection in kidney transplant recipients (INCREMENT-SOT Project)

BACKGROUND

Whether active therapy with β-lactam/β-lactamase inhibitors (BLBLI) is as affective as carbapenems for extended-spectrum β-lactamase-producing Enterobacterales (ESBL-E) bloodstream infection (BSI) secondary to urinary tract infection (UTI) in kidney transplant recipients (KTRs) remains unclear.

METHODS

We retrospectively evaluated 306 KTR admitted to 30 centers from January 2014 to October 2016. Therapeutic failure (lack of cure or clinical improvement and/or death from any cause) at days 7 and 30 from ESBL-E BSI onset was the primary and secondary study outcomes, respectively.

RESULTS

Therapeutic failure at days 7 and 30 occurred in 8.2% (25/306) and 13.4% (41/306) of patients. Hospital-acquired BSI (adjusted OR [aOR]: 4.10; 95% confidence interval [CI]: 1.50-11.20) and Pitt score (aOR: 1.47; 95% CI: 1.21-1.77) were independently associated with therapeutic failure at day 7. Age-adjusted Charlson Index (aOR: 1.25; 95% CI: 1.05-1.48), Pitt score (aOR: 1.72; 95% CI: 1.35-2.17), and lymphocyte count ≤500 cells/μL at presentation (aOR: 3.16; 95% CI: 1.42-7.06) predicted therapeutic failure at day 30. Carbapenem monotherapy (68.6%, primarily meropenem) was the most frequent active therapy, followed by BLBLI monotherapy (10.8%, mostly piperacillin-tazobactam). Propensity score (PS)-adjusted models revealed no significant impact of the choice of active therapy (carbapenem-containing vs any other regimen, BLBLI- vs carbapenem-based monotherapy) within the first 72 hours on any of the study outcomes.

CONCLUSIONS

Our data suggest that active therapy based on BLBLI may be as effective as carbapenem-containing regimens for ESBL-E BSI secondary to UTI in the specific population of KTR. Potential residual confounding and unpowered sample size cannot be excluded (ClinicalTrials.gov identifier: NCT02852902).

High mortality associated with gram-negative bacterial bloodstream infection in liver transplant recipients undergoing immunosuppression reduction

BACKGROUND

Immunosuppression is an important factor in the incidence of infections in transplant recipient. Few studies are available on the management of immunosuppression (IS) treatment in the liver transplant (LT) recipients complicated with infection. The aim of this study is to describe our experience in the management of IS treatment during bacterial bloodstream infection (BSI) in LT recipients and assess the effect of temporary IS withdrawal on 30 d mortality of recipients presenting with severe infection.

AIM

To assess the effect of temporary IS withdrawal on 30 d mortality of LT recipients presenting with severe infection.

METHODS

A retrospective study was conducted with patients diagnosed with BSI after LT in the Department of Liver Surgery, Renji Hospital from January 1, 2016 through December 31, 2017. All recipients diagnosed with BSI after LT were included. Univariate and multivariate Cox regression analysis of risk factors for 30 d mortality was conducted in the LT recipients with Gram-negative bacterial (GNB) infection.

RESULTS

Seventy-four episodes of BSI were identified in 70 LT recipients, including 45 episodes of Gram-positive bacterial (GPB) infections in 42 patients and 29 episodes of GNB infections in 28 patients. Overall, IS reduction (at least 50% dose reduction or cessation of one or more immunosuppressive agent) was made in 28 (41.2%) cases, specifically, in 5 (11.9%) cases with GPB infections and 23 (82.1%) cases with GNB infections. The 180 d all-cause mortality rate was 18.5% (13/70). The mortality rate in GNB group (39.3%, 11/28) was significantly higher than that in GPB group (4.8%, 2/42) (P = 0.001). All the deaths in GNB group were attributed to worsening infection secondary to IS withdrawal, but the deaths in GPB group were all due to graft-versus-host disease. GNB group was associated with significantly higher incidence of intra-abdominal infection, IS reduction, and complete IS withdrawal than GPB group (P < 0.05). Cox regression showed that rejection (adjusted hazard ratio 7.021, P = 0.001) and complete IS withdrawal (adjusted hazard ratio 12.65, P = 0.019) were independent risk factors for 30 d mortality in patients with GNB infections after LT.

CONCLUSION

IS reduction is more frequently associated with GNB infection than GPB infection in LT recipients. Complete IS withdrawal should be cautious due to increased risk of mortality in LT recipients complicated with BSI.

IS

The use of automated data extraction tools to develop a solid organ transplant registry: Proof of concept study of bloodstream infections

BACKGROUND

We created an electronic health record-based registry using automated data extraction tools to study the epidemiology of bloodstream infections (BSI) in solid organ transplant recipients. The overarching goal was to determine the usefulness of an electronic health record-based registry using data extraction tools for clinical research in solid organ transplantation.

METHODS

We performed a retrospective single-center cohort study of adult solid organ transplant recipients from 2010 to 2015. Extraction tools were used to retrieve data from the electronic health record, which was integrated with national data sources. Electronic health records of subjects with positive blood cultures were manually adjudicated using consensus definitions. One-year cumulative incidence, risk factors for BSI acquisition, and 1-year mortality were analyzed by Kaplan-Meier method and Cox modeling, and 30-day mortality with logistic regression.

RESULTS

In 917 solid organ transplant recipients the cumulative incidence of BSI was 8.4% (95% confidence interval 6.8-10.4) with central line-associated BSI as the most common source. The proportion of multidrug-resistant isolates increased from 0% in 2010 to 47% in 2015 (p = 0.03). BSI was the strongest risk factor for 1-year mortality (HR=8.44; 4.99-14.27; p<0.001). In 11 of 14 deaths, BSI was the main cause or contributory in patients with non-rapidly fatal underlying conditions.

CONCLUSIONS

Our study illustrates the usefulness of an electronic health record-based registry using automated extraction tools for clinical research in the field of solid organ transplantation. A BSI reduces the 1-year survival of solid organ transplant recipients. The most common sources of BSIs in our studies are preventable.

Impact of deceased donor multidrug-resistant bacterial organisms on organ utilization

The extent to which donor multidrug-resistant organisms (MDROs) affect organ utilization remains unclear. We performed a retrospective cohort study at 4 transplant centers between 2015 and 2016 to evaluate this question. All deceased donors who donated at least one organ were included. Exposed donors had at least one MDRO on culture. Unexposed donors had no MDRO-positive cultures. Only cultures obtained during the donor's terminal hospitalization were evaluated. Multivariable regression was used to determine the association between donor MDRO and (1) number of organs transplanted per donor and (2) the match run at which each organ was accepted. Subsequently, we restricted the analysis to donors with MDR-Gram-negative (GN) organisms. Of 440 total donors, 29 (7%) donors grew MDROs and 7 (2%) grew MDR-GNs. There was no significant association between donor MDRO and either measure of organ utilization. However, donor MDR-GNs were associated with a significant reduction in the number of organs transplanted per donor (incidence rate ratio 0.43, 95% confidence interval [CI] 0.39-0.48, P < .01), and organs were accepted significantly further down the match list (relative count 5.08, 95% CI 1.64-15.68, P = .01). Though donor MDR-GNs were infrequent in our study, their growing prevalence could meaningfully reduce the donor pool over time.

Risk Factors for Acquisition of Carbapenem-Resistant Klebsiella pneumoniae and Mortality Among Abdominal Solid Organ Transplant Recipients with K. pneumoniae Infections

Background

For abdominal solid organ transplant (ASOT) recipients, infection with Klebsiella pneumoniae, particularly carbapenem-resistant K. pneumoniae (CRKP), can be life-threatening. The aims of this study were to characterize the risk factors associated with acquisition of CRKP and 90-day crude mortality among patients.

Material/Methods

In our cohort study, we retrospectively reviewed 68 K. pneumoniae-infected transplant recipients, studied their demographics, clinical manifestations, microbiology, and outcomes, and determined the risk factors associated with the occurrence of CRKP and crude mortality due to K. pneumoniae infections.

Results

Sixty-eight ASOT recipients (5.4%) experienced 78 episodes of K. pneumoniae infection. Among these, 20 patients (29.4%) died. The independent risk factors associated with mortality were multiple infected organs or sites (odds ratio=22.034, 95% confidence intervals=4.348–111.653, P=0.001) and septic shock (odds ratio=27.090, 95% confidence intervals=1.841–398.512, P=0.016). Risk factors associated with acquisition of CRKP were multiple infected organs or sites (odds ratio=3.056, 95% confidence intervals=1.091–8.556, P=0.033).

Conclusions

K. pneumoniae infections, especially CRKP, frequently occurred among ASOT recipients, with a high mortality rate. Multiple infected organs or sites and septic shock were predictors of crude mortality caused by K. pneumoniae infections, while CRKP infections were associated with multiple infected organs or sites. Greater efforts are needed towards improved antibiotic administration, early diagnosis and precise treatment, recognition of septic shock, and reduced length of hospitalization.

Bloodstream infections by gram-negative bacteria in kidney transplant patients: Incidence, risk factors, and outcome

BACKGROUND

Kidney transplant recipients (KTRs) are at increased risk of infections.

METHODS

The aims of this study were to describe the incidence of bloodstream infections (BSIs) by gram-negative bacteria in a cohort of KTRs, the risk factors for BSI due to multi-drug-resistant (MDR) gram-negative bacteria, and the predictors for unfavorable outcome, defined as death or nephrectomy or return to dialysis, within 30 days from BSI. We conducted a retrospective cohort study at the renal transplant unit of a tertiary care hospital in Athens, Greece.

RESULTS

In a total of 1962 KTRs, we recorded 195 BSI episodes in 182 single patients (male/female = 97/85), with a median (interquartile range) age of 57.2 (44-64.9) years. The incidence was 1.393/100 patient-years. The most common source of infection was urinary tract (70.9%), and Escherichia coli (63.7%) was the most common pathogen. 19.2% of the infecting organisms were MDR; previous antibiotic use (OR 8.2; CI 2.1-32.9) and previous stay in the intensive care unit (OR 34.2; CI 1.6-730.2) were associated with MDR BSIs. 6% of patients died, and 2.2% underwent nephrectomy, while no patients had to return to dialysis. Diabetes mellitus (OR 8.1; 95% CI 1.3-50.3), Pseudomonas aeruginosa BSI (OR 46.1; 95% CI 3.9-552.3), and septic shock (OR 46.7; 95% CI 1.7-1304.9) were independent predictors of unfavorable outcome.

CONCLUSION

Bloodstream infections in KTRs have a significant impact on allograft and patients outcome.

Epidemiology and risk factors for invasive fungal disease in liver transplant recipients in a tertiary transplant center

BACKGROUND

Invasive fungal disease (IFD) in liver transplant recipients causes significant morbidity and mortality. We aim to describe institutional epidemiology and risk factors for IFD in the liver transplant population.

METHODS

We conducted a retrospective cohort study of all adult liver transplant recipients in our institution from 2005 to October 2015 to describe the epidemiology of patients with proven and probable IFD according to the European Organization for Research and Treatment of Cancer/Mycoses Study Group criteria. To determine risk factors for IFD, a case-control study was also conducted. Cases were defined as liver transplant recipients with proven or probable IFD, and controls were defined as liver transplant recipients without IFD. Each case was matched to two controls by age (±10 years of age), gender, and time of transplant (within one year of the case).

RESULTS

28/554 (5.1%) patients developed IFD. Candidiasis (n = 11; 39.3%), Aspergillosis (n = 10; 35.7%), and Cryptococcosis (n = 3; 10.7%) were the most common fungal infections in the proven and probable IFD groups. Mold infections occurred in 13 (46.4%) cases. Reoperation, roux-en-y anastomosis, and massive intraoperative transfusion of ≥40 units of cellular blood products were major risk factors for IFD in the multivariate analysis.

CONCLUSION

Candida and Aspergillus are the most common causes of IFD in liver transplantation in our center. There is significant overlap in risk factors for such infections post-transplantation. In our cohort, critically ill patients with complicated perioperative course seem to predispose them to mold infections post-transplantation, but larger studies are required to better delineate risk factors for mold infection as well as determine the efficacy and optimal duration of mold prophylaxis in liver transplantation. With increasing echinocandin use for antifungal prophylaxis, it is also important to monitor for emerging antifungal resistance.

Streptococcus canis Bacteremia in a Renal Transplant Recipient

A middle-aged man presented with fever and shortness of breath. He had significant history of congestive heart disease and received deceased donor renal transplant 2 years prior to presentation. He was febrile and found to have sepsis. His initial blood cultures grew Streptococcus canis. Streptococcus canis causes rare infection in humans, and this is most likely the first case in the renal transplant population.

Management of Antimicrobial Agents in Abdominal Organ Transplant Patients in Intensive Care Unit

PURPOSE OF REVIEW

Early diagnosis of infections and immediate initiation of appropriate antimicrobials are crucial in the management of patients before and after organ transplantation. We reviewed the most recent literature and guidelines in this field and organized the current recommendations for healthcare professionals caring for critically ill organ transplant recipients.

RECENT FINDINGS

The incidence of multidrug-resistant organisms is increasing. Multidrug-resistant Gram-negative bacteria comprise about 14% of organisms. Vancomycin-resistant enterococci bloodstream infections are also on the rise, as 20.5% of nosocomial enterococci are now vancomycin-resistant, changing empiric antibiotic selection. Fluconazole-resistant Candida species comprise up to 46% of cases of candidemia in hospitalized patients. Consequently, new guidelines recommend primary use of echinocandins in patients with candidemia who have moderate-to-severe disease. Finally, the incidence of emergence of ganciclovir-resistant cytomegalovirus infection in patients is 5-12%, requiring early recognition and change to alternative regimens in the case of poor response to therapy.

SUMMARY

Bloodstream infections are a major cause of mortality and morbidity in solid organ transplantation. Mortality as high as 24% and 50% have been reported with sepsis and septic shock respectively. As such, bloodstream infections should be diagnosed rapidly and intravenous antibiotics should be started immediately. Appropriate resuscitation should be initiated and the number and/or dose of immunosuppressive drugs should be reduced. Proper source control must also be achieved with radiologic drainage or surgical intervention as appropriate. Initial antibiotic treatment of these patients should cover both Gram-positive organisms, especially in the presence of intravascular catheters, and Gram-negative bacteria. Echinocandins like caspofungin should also be considered especially in critically ill patients, particularly if a patient has been on total parenteral nutrition or broad-spectrum antibiotics.