High mortality associated with Acinetobacter species infection in liver transplant patients

Extensive Drug Resistance of Strong Biofilm-Producing Acinetobacter baumannii Strains Isolated from Infections and Colonization Hospitalized Patients in Southern Poland

Acinetobacter baumannii (AB) is a bacterium that causes infections, particularly in immunocompromised patients. Treatment is challenging due to biofilm formation by AB strains, which hinders antibiotic effectiveness and promotes drug resistance. The aim of our study was to analyze the biofilm-producing capacity of AB isolates from various forms of infections in relation to biofilm-related genes and their drug resistance. We tested one hundred isolates for biofilm formation using the crystal violet microplate method. Drug resistance analyses were performed based on EUCAST and CLSI guidelines, and biofilm genes were detected using PCR. All tested strains were found to form biofilms, with 50% being ICU strains and 72% classified as strong biofilm producers. Among these, 87% were extensively drug-resistant (XDR) and 2% were extra-extensively drug-resistant (E-XDR). The most common gene set was bap, bfmS, csuE, and ompA, found in 57% of all isolates. Our research shows that, regardless of the form of infection, biofilm-forming strains can be expected among AB isolates. The emergence of E-XDR and XDR strains among non-ICU infections highlights the necessity for the rational use of antibiotics to stop or limit the further acquisition of drug resistance by A. baumannii.

Risk factors and outcomes of early infection in liver transplant recipients with acute-on-chronic liver failure

OBJECTIVES

Patients with acute-on-chronic liver failure (ACLF) have a high risk of infection after liver transplantation (LT). In this study, we aimed to evaluate the prevalence of early post-LT infection (within one month after LT) in recipients with ACLF, and to compare the survival rate between patients with or without post-LT infection.

METHODS

Patients with ACLF who underwent LT between January 2015 and December 2017 were retrospectively included. Characteristics of the patients, prevalence, site and pathogen of post-LT infection, and its risk factors were evaluated.

RESULTS

A total of 62 patients with ACLF developed bacterial or fungal infection after LT. The 30-day, 90-day, and 1-year survival rates in the infected group were found to be significantly lower than those in the non-infected group (67.7% vs 98.5%, 64.5% vs 97.7%, and 48.4% vs 95.4%; all P  < 0.001). The most common pathogens involved were carbapenem-resistant gram-negative organisms, including Acinetobacter baumannii, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Acinetobacter lwoffi. Multivariate analysis demonstrated that reoperation and length of intensive care unit stay were independently associated with post-LT infection. In addition, living donor LT and early allograft dysfunction were independently associated with 30-day all-cause mortality, whereas red blood cell transfusion and post-LT infection were independently associated with all-cause 30-day and 90-day mortality after LT.

CONCLUSIONS

Early infection after LT is a major prognostic factor in patients with ACLF. Constant vigilance for the risk factors of early infection after LT is needed for timely diagnosis and prompt intervention.

Drug Resistance and Risk Factors for Acquisition of Gram-Negative Bacteria and Carbapenem-Resistant Organisms Among Liver Transplant Recipients

Introduction

Infections caused by Gram-negative bacteria, in particular carbapenem-resistant organisms (CRO), pose a great threat to liver transplant (LT) recipients. Understanding the risk factors for Gram-negative and CRO infections and the drug resistance of corresponding bacteria will help guide the prevention and treatment of these infections.

Methods

Data on the composition, distribution and drug resistance of Gram-negative bacteria and CRO among LT recipients were collected. The risk factors for Gram-negative and CRO infections were identified via univariate and multivariate analysis.

Results

A total of 45 episodes of Gram-negative infection, including 20 episodes of CRO infection, occurred in 19.9% (27/136) of LT recipients. Klebsiella pneumoniae was the dominant pathogenic bacteria (14/45; 31.1%). The most common site of infection was the abdominal cavity/bile duct (11/27; 40.7%). Eleven (8.1%) patients died within 2 months after LT, and two deaths were related to Gram-negative infection. Gram-negative bacteria were relatively sensitive to tigecycline and polymyxin B, with resistance of 26.7 and 11.1%, respectively. CRO had lower resistance to ceftazidime/avibactam (45.5%) and polymyxin B (10%). A univariate analysis showed that male sex, infection within 2 months prior to LT, duration of surgery ≥ 400 min, reoperation, indwelling urethral catheter use ≥ 3 days and elevated alanine aminotransferase on day 1 post-LT were associated with Gram-negative infection. Multivariate logistic regression analysis revealed that infection within 2 months prior to LT [odds ratio (OR) = 4.426, 95%CI: 1.634–11.99, P = 0.003], duration of surgery ≥ 400 min [OR = 3.047, 95%CI: 1.194–7.773, P = 0.02] and indwelling urethral catheter use ≥ 3 days [OR = 5.728, 95%CI: 1.226–26.763, P = 0.026] were independent risk factors for Gram-negative infection after LT, and that only carbapenem use ≥ 3 days within 15 days prior to infection [OR = 14, 95%CI: 1.862–105.268, P = 0.01] was related to the occurrence of CRO infections.

Conclusion

The incidence of Gram-negative and CRO infections was high in the early post-LT period. The most common infection site was the abdominal cavity/bile duct, and the dominant pathogen was K. pneumoniae. Patients with infections within 2 months prior to LT, prolonged surgery time or delayed urethral catheter removal were prone to Gram-negative infection. Carbapenem exposure was correlated with CRO infections.

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.

Prevalence, Risk Factors And Treatment Of The Most Common Gram-Negative Bacterial Infections In Liver Transplant Recipients: A Review

Advances in surgical techniques and immunosuppressive agents have made solid organ transplant (Tx) an important strategy for treatment of end-stage organ failures. However, the incidence of infections following Tx due to Gram-negative pathogens is on the rise. These infections are associated with increased mortality and morbidity in patients following transplantation, including liver Tx. Thus, managing infections in liver Tx recipients is a big challenge, requiring prompt medical attention. Considering the important effect of Gram-negative bacterial infections on the outcomes of liver Tx recipients, the most prevalent Gram-negative pathogens including Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa and Escherichia coli will be discussed in this review.

Carbapenemase-Producing Bacterial Infections in Patients With Liver Transplant

Carbapenemase-producing Enterobacteriacea (CPE) cause serious and life-threatening infections. They are resistant to carbapenems and many other classes of commonly used antimicrobial agents; therefore, managing infections caused by them poses a substantial challenge in clinical practice. They can also cause morbidity and mortality in patients with liver transplant. A retrospective analysis of CPE culture-positive patients with a history of liver transplant can help to examine the epidemiology and microbiology of these bacteria, as well as gain information on the possible infection sources, susceptibility patterns, and expected mortality in infected populations. In addition, study of these bacteria could help formulate a consensus on the appropriate use of empirical and directed antibiotic therapy, which can effectively reduce infections in these patients. We reviewed the medical records of 142 subjects who underwent liver transplantation at Ankara University Hospital, a 1900-bed tertiary care university hospital, in Ankara, Turkey, between January 2014 and August 2018. Patients showing signs of infection with culture positivity for CPE-producing organisms were included from the study. Statistical analysis was performed and a value of P < .05 is considered statistically significant. In most cases, the source of infection was the abdomen. Klebsiella species was also predominant in these cases. Model for End-Stage Liver Disease scores and length of hospital stay were higher and statistically significant when compared to patients who were CPE negative. Mortality was highest in the CPE-positive group. Infection is the most important cause of mortality and morbidity after liver transplantation and increases the cost of treatment. Regarding the culture sensitivity patterns and resistance mode, empirical therapy with carbapenems does not produce a solid result. The high mortality observed with these infections reflects very limited therapeutic options.

Infections in Liver Transplantation

Liver transplantation has become an important treatment modality for patients with end-stage liver disease/cirrhosis, acute liver failure, and hepatocellular carcinoma. Although surgical techniques and immunosuppressive regimens for liver transplantation have improved significantly over the past 20 years, infectious complications continue to contribute to the morbidity and mortality in this patient population. The use of standardized screening protocols for both donors and recipients, coupled with targeted prophylaxis against specific pathogens, has helped to mitigate the risk of infection in liver transplant recipients. Patients with chronic liver disease and cirrhosis have immunological deficits that place them at increased risk for infection while awaiting liver transplantation. The patient undergoing liver transplantation is prone to develop healthcare-acquired infections due to multidrug-resistant organisms that could potentially affect patient outcomes after transplantation. The complex nature of liver transplant surgery that involves multiple vascular and hepatobiliary anastomoses further increases the risk of infection after liver transplantation. During the early post-transplantation period, healthcare-acquired bacterial and fungal infections are the most common types of infection encountered in liver transplant recipients. The period of maximal immunosuppression that occurs at 1–6 months after transplantation can be complicated by opportunistic infections due to both primary infection and reactivation of latent infection. Severe community-acquired infections can complicate the course of liver transplantation beyond 12 months after transplant surgery. This chapter provides an overview of liver transplantation including indications, donor-recipient selection criteria, surgical procedures, and immunosuppressive therapies. A focus on infections in patients with chronic liver disease/cirrhosis and an overview of the specific infectious complications in liver transplant recipients are presented.

Ascitic Bacterial Composition Is Associated With Clinical Outcomes in Cirrhotic Patients With Culture-Negative and Non-neutrocytic Ascites

Ascites bacterial burden is associated with poor clinical outcomes in patients with end-stage liver disease. However, the impact of ascitic microbial composition on clinical course was still not clear. In this study, the ascitic microbiota composition of 100 cirrhotic patients with culture-negative and non-neutrocytic ascites were researched with 16S rRNA pyrosequencing and enterotype-like cluster analysis. Results: By characterizing the ascitic microbial composition, two distinct microbial clusters were observed, Cluster 1 (86 patients) and Cluster 2 (14 patients). Cluster 1 showed lower microbial richness than Cluster 2. At the phylum level, Cluster 1 had greater abundance of Bacteroidetes and Firmicutes, but less abundance of Proteobacteria and Actinobacteria than Cluster 2. At the family level, family Bacteroidales S24-7 group, Prevotellaceae, Lachnospiraceae, Lactobacillaceae, Rikenellaceae, and Vibrionaceae were found over-represented in Cluster 1. And family Acetobacteraceae, Erysipelotrichaceae, Rickettsiaceae, and Streptococcaceae were found enriched in Cluster 2. The levels of plasma cytokine IL-17A, IL-7, and PDGF-BB were found significantly higher in Cluster 1 than in Cluster 2. There were four OTUs closely correlated with plasma cytokines, which were OTU 140 and OTU 271 (both from Bacteroidales S24-7 group), OTU 68 (Veillonellaceae), and OTU 53 (Helicobacteraceae). Patients from Cluster 1 showed significant higher short-term mortality than patients from Cluster 2. Conclusion: Our study demonstrated that the microbial composition of culture-negative and non-neutrocytic ascites in cirrhotic patients is associated with short-term clinical outcomes. The results here offer a rational for the identification of patients with high risk, and provide references for selective use of prophylactic methods.

Early Bacterial Pneumonia After Hepatic Transplantation: Epidemiologic Profile

BACKGROUND

Postoperative pulmonary complications are major cause of morbidity and mortality in patients receiving liver transplantation (LT), particularly bacterial pneumonia occurring within the first 100 days after transplantation. Our aim in this study was to determine the incidence, microorganisms involved, associated factors, and morbidity of bacterial pneumonia presenting in the first 100 days posttransplant.

METHODS

We performed a cohort study in which patients receiving liver transplantation were included prospectively in our national database (Database of Infections in Transplantation of Solid Organs). The study period was from July 14, 2009 to July 24, 2015.

RESULTS

One hundred six patients were transplanted during the 6-year period. We documented 9 bacterial pneumonia cases with an incidence of 8.5 per 100 patients; 2 patients had hospital-acquired pneumonia (HAP) and 7 had ventilator-associated pneumonia (VAP). In 4 of the 9 bacterial pneumonia cases, patients presented with bacteremia. Eleven microorganisms were isolated these 9 patients. Microbiologic diagnosis methods included 5 cases of alveolar bronchoalveolar lavage (BAL), 1 case of BAL and pleural fluid puncture, 1 case of pleural fluid puncture, and 1 case through sputum study. Of the 11 isolated organisms, 9 corresponded to Gram-negative bacilli (GNB): Klebsiella spp, n = 3; Acinetobacter baumannii, n = 4; Morganella morganii, n = 1; and Pseudomonas aeruginosa, n = 1. Regarding the resistance profile, 7 presented with a multiresistance profile (MDR) and extreme resistance (XDR). Univariate analysis identified the Model for End-Stage Liver Disease (MELD) pretransplant score as a factor associated with developing pneumonia (P < .001, 95% confidence interval [CI] 2.872-10.167), and early extubation, before 8 hours posttransplant, as a protective factor (P = .008; relative risk [RR] 0.124; 95% CI 0 .041-0.377). Hospital stay was longer in patients with pneumonia compared to those without pneumonia (P < .0001, 95% CI 17.79-43.11 days). There was also an increased risk of death in patients with pneumonia (RR 17.963; 95% CI 5106-63,195).

CONCLUSIONS

Early bacterial pneumonia after hepatic transplantation is associated with higher morbidity and mortality. At our center, 4 of 9 patients had bacteremia. GNB cases with MDR and XDR profiles are predominant. Early extubation is a protective factor.

Clinical Characteristics of Acinetobacter baumannii Infection in Solid-Organ Transplant Recipients

OBJECTIVES

Acinetobacter baumannii, depending on the immune status of the host, may result in one of the most serious hospital infections. Infections involving A. baumannii infection have been recently rising. However, little is known about the clinical features of A. baumannii infection in solid-organ transplant recipients. We aimed to share our clinical experiences with A. baumannii infection in our transplant recipients.

MATERIALS AND METHODS

Between 2011 and 2017, 41 solid-organ transplant patients developed A. baumannii infection at Baskent University Hospital. Medical records were reviewed, and patient demographics, microbiology results, and overall outcome data were noted.

RESULTS

Of 41 solid-organ transplant patients with A. baumannii infection, 29 were male and 12 were female patients with mean age of 47.15 ± 13.24 years. Our infection rate with A. baumannii infection was 6.1%. The most common sites of infection were deep tracheal aspirate (48.8%)and bloodstream (36.6%). Onset of infection 1 year posttransplant was identified in 58.5% of recipients. Risk factors included presence of invasive procedures (56.1%) and administration of high-dose corticosteroids for rejection 1 year before infection (68.3%). Thirty-day mortality rate was 41.5% (17/41 patients) and was not associated with the infection site, microbiological cure, clinical cure, and drug resistance in our study group.

CONCLUSIONS

Acinetobacter baumannii is an important cause of hospital-acquired infection and mortality worldwide. A major problem with A. baumannii infection is delayed initiation of appropriate antibiotic treatment and the rising numbers of extensively drug-resistant organisms. Predicting the potential risk factors, especially in the already at-risk solid-organ transplant population, has an important role in patient outcomes.

Epidemiological Analysis of Extended-Spectrum Beta-Lactamase-Producing Bacterial Infections in Adult Live Donor Liver Transplant Patients

Introduction:

Bacterial infections are a leading cause of morbidity and mortality in patients receiving solid-organ transplants. Extended-spectrum beta-lactamases (ESBL) pathogens are the most important pathogenic bacteria infecting these patients.

Aim:

This study aims to evaluate for the incidence and characteristics of ESBL-positive organism, to look for the clinical outcomes in ESBL-positive infected cases, and to evaluate and draft the antibiotic policy in posttransplant patients during the first 28 days posttransplant.

Materials and Methods:

This is a retrospective data analysis of liver transplant recipients infected with ESBL culture-positive infections. All the culture sites such as blood, urine, and endotracheal tube aspirates were screened for the first ESBL infection they had and noted. This data were collected till day 28 posttransplant. The antibiotic susceptibility pattern and the most common organism were also noted.

Results:

A total of 484 patients was screened and 116 patients had ESBL-positive cultures. Out of these, 54 patients had infections and 62 patients were ESBL colonizers. The primary infection site was abdominal fluid (40.7%), with Klebsiella accounting for most of the ESBL infections. Colistin was the most sensitive antibiotic followed by tigecycline. The overall mortality was 11.4% and 31 out of 54 ESBL-infected patients died.

Conclusions:

Infections with ESBL-producing organism in liver transplant recipients has a high mortality and very limited therapeutic options.

Antibiotic-Resistant Infections and Treatment Challenges in the Immunocompromised Host

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.

Management of multidrug resistant Gram-negative bacilli infections in solid organ transplant recipients: SET/GESITRA-SEIMC/REIPI recommendations

Solid organ transplant (SOT) recipients are especially at risk of developing infections by multidrug resistant (MDR) Gram-negative bacilli (GNB), as they are frequently exposed to antibiotics and the healthcare setting, and are regulary subject to invasive procedures. Nevertheless, no recommendations concerning prevention and treatment are available. A panel of experts revised the available evidence; this document summarizes their recommendations: (1) it is important to characterize the isolate's phenotypic and genotypic resistance profile; (2) overall, donor colonization should not constitute a contraindication to transplantation, although active infected kidney and lung grafts should be avoided; (3) recipient colonization is associated with an increased risk of infection, but is not a contraindication to transplantation; (4) different surgical prophylaxis regimens are not recommended for patients colonized with carbapenem-resistant GNB; (5) timely detection of carriers, contact isolation precautions, hand hygiene compliance and antibiotic control policies are important preventive measures; (6) there is not sufficient data to recommend intestinal decolonization; (7) colonized lung transplant recipients could benefit from prophylactic inhaled antibiotics, specially for Pseudomonas aeruginosa; (8) colonized SOT recipients should receive an empirical treatment which includes active antibiotics, and directed therapy should be adjusted according to susceptibility study results and the severity of the infection.

A Case of Early detected Multidrug-resistant Acinetobacter baumannii Infection after Liver Transplantation

Invasive bacterial infections have become the leading cause of morbidity and mortality among solid organ transplant recipients (SOTRs). Acinetobacter baumannii can cause a serious infection in SOTRs. Multidrug-resistant A. baumannii (MDR-Ab) represents a major problem in liver transplant recipients. Here, we presented a respiratory infection related to MDR-Ab pathogenesis in a patient who underwent liver transplantation due to acute hepatic failure. Accordingly, it has been emphasized that infections after the liver transplantation should be accomplished after due consideration of all relevant facts with a multidisciplinary approach.

Does Thymoglobulin Induction Increase Susceptibility to Carbapenem-Resistant Acinetobacter baumannii Sepsis-related Death in Expanded Criteria Donors?

BACKGROUND

Solid organ transplant recipients are susceptible to antibiotic-resistant infections and carbapenem-resistant Acinetobacter baumannii (CRAB) has recently been recognized as a serious complication in solid organ recipients. High mortality rates have been described.

METHODS

We retrospectively analyzed 807 transplantations and detected 10 patients who died 24 hours after the diagnosis of septicemia, all with CRAB-positive blood cultures. Recipients were followed up for at least 1 year and were stratified into the following groups: Group 1, patients alive; Group 2, patients that died due to other causes except Acinetobacter infection; and Group 3, patients who died within 24 hours of CRAB diagnosis.

RESULTS

CRAB-positive patients died a median of 3.17 (range, 1.81-18.7) months after transplantation. In these patients, expanded criteria donors (ECDs) were more frequent (P < .001), as were the use of anti-thymocyte globulin (ATG) induction (P = .02) and delayed graft function (P = .01). For ECD recipients, death rate from any cause, whether induced with ATG or not, was 25% and 20.6%, respectively (odds ratio [OR], 1.28; confidence interval [CI] 95%, 0.56-2.91; P = .68). The death rate from CRAB-related sepsis was 10.3% and 0% whether receiving ATG or not, respectively (OR, 15.49; CI 95%, 0.87-277.16; P = .014). There was a 25.75-fold increase in the death rate in ECD kidney recipients induced with thymoglobulin and with CRAB-related sepsis.

CONCLUSION

Transplants from ECDs and induced with thymoglobulin may be at increased risk of CRAB death in 24 hours when compared with patients with standard donors and induced with thymoglobulin.

Multidrug-resistant organisms in liver transplant: Mitigating risk and managing infections

Liver transplant (LT) recipients are vulnerable to infections with multidrug-resistant (MDR) pathogens. Risk factors for colonization and infection with resistant bacteria are ubiquitous and unavoidable in transplantation. During the past decade, progress in transplantation and infection prevention has contributed to the decreased incidence of infections with methicillin-resistant Staphylococcus aureus. However, even in the face of potentially effective antibiotics, vancomycin-resistant enterococci continue to plague LT. Gram-negative bacilli prove to be more problematic and are responsible for high rates of both morbidity and mortality. Despite the licensure of novel antibiotics, there is no universal agent available to safely and effectively treat infections with MDR gram-negative organisms. Currently, efforts dedicated toward prevention and treatment require involvement of multiple disciplines including transplant providers, specialists in infectious diseases and infection prevention, and researchers dedicated to the development of rapid diagnostics and safe and effective antibiotics with novel mechanisms of action. Liver Transplantation 22 1143-1153 2016 AASLD.

Assessment of microbial communities in PM1 and PM10 of Urumqi during winter

Recently, inhalable particulate matter has been reported to carry microorganisms responsible for human allergy and respiratory disease. The unique geographical environment and adverse weather conditions of Urumqi cause double pollution of dust and smog, but research on the microbial content of the atmosphere has not been commenced. In this study, 16S and 18S rRNA gene sequencing were conducted to investigate the microbial composition of Urumqi's PM1 and PM10 pollutants in winter. Results showed that the bacterial community is mainly composed of Proteobacteria, Firmicutes and Actinobacteria, Proteobacteria accounted for the most proportion which was significant difference in some aforementioned studies. Ascomycota and Basidiomycota constitute the main part of the fungal microbial community. The difference of bacterial relative abundance in sample point is greater than in particle sizes. The sequences of several pathogenic bacteria and opportunistic pathogens were also detected, such as Acinetobacter, Delftia, Serratia, Chryseobacterium, which may impact on immunocompromised populations (elderly, children and postoperative convalescence patients), and some fungal genera may cause several plant diseases. Our findings may serve an important reference value in the global air microbial propagation and air microbial research in desert.

Rapid Detection of Bloodstream Pathogens in Liver Transplantation Patients With FilmArray Multiplex Polymerase Chain Reaction Assays: Comparison With Conventional Methods

BACKGROUND

Bloodstream infection (BSI) is an important concern in transplant patients. Early intervention with appropriate antimicrobial therapy is critical to better clinical outcome; however, there is significant delay when conventional identification methods are used.

METHODS

We aimed to determine the diagnostic performance of the FilmArray Blood Culture Identification Panel, a recently approved multiplex polymerase chain reaction assay detecting 24 BSI pathogens and 3 resistance genes, in comparison with the performances of conventional identification methods in liver transplant (LT) patients. A total of 52 defined sepsis episodes (signal-positive by blood culture systems) from 45 LT patients were prospectively studied.

RESULTS

The FilmArray successfully identified 37 of 39 (94.8%) bacterial and 3 of 3 (100%) yeast pathogens in a total of 42 samples with microbial growth, failing to detect only 2 of 39 (5.1%) bacterial pathogens that were not covered by the test panel. The FilmArray could also detect additional pathogens in 3 samples that had been reported as having monomicrobial growth, and it could detect Acinetobacter baumannii in 2 samples suspected of skin flora contamination. The remaining 8 blood cultures showing a positive signal but yielding no growth were also negative by this assay. Results of MecA, KPC, and VanA/B gene detection were in high accordance. The FilmArray produced results with significantly shorter turnaround times (1.33 versus 36.2, 23.6, and 19.5 h; P < .05) than standard identification methods, Vitek II, and Vitek MS, respectively.

CONCLUSIONS

This study showed that the FilmArray appeared as a reliable alternative diagnostic method with the potential to mitigate problems with protracted diagnosis of the BSI pathogens in LT patients.

Predictors of mortality in solid-organ transplant recipients with infections caused by Acinetobacter baumannii

Acinetobacter baumannii can cause a serious infection in solid-organ transplant (SOT) recipients, and more data on A. baumannii infection is needed. We sought to investigate the epidemiology and distribution of A. baumannii isolates in SOT recipients. We also investigated the risk factors for overall in-hospital mortality and infection-related 30-day mortality using multivariate logistic regression analysis. A double-center retrospective study of SOT recipients who were infected with A. baumannii between January 2003 and January 2015 was conducted. A total of 71 individuals developed 93 episodes of A. baumannii infection, with a mean age of 44.5 years (44.5±11.9 years). Ninety percent of recipients had nosocomial origin A. baumannii infection, with the bloodstream as the most common site of infection (32.4%). Septic shock developed in 23.9% (17 of 71) of all recipients with A. baumannii infection. Morbidity and mortality rates of A. baumannii infections were high in SOT recipients. The incidence rate of A. baumannii infection in SOT recipients was 3.9% (71 of 1,821). Overall in-hospital mortality and infection-related 30-day mortality were 53.5% (38 of 71) and 40.8% (29 of 71), respectively. Risk factors independently associated with overall in-hospital mortality were mechanical ventilation at onset of A. baumannii infection (odds ratio [OR] 6.29, 95% confidence interval [CI] 1.48–26.85; P=0.013), liver or liver–kidney transplantation (OR 15.33, 95% CI 1.82–129.18; P=0.012), and late-onset A. baumannii infection (OR 7.61, 95% CI 1.07–54.36; P=0.043). A platelet count <50,000/mm³ (OR 12.76, 95% CI 1.28–126.81; P=0.030) and mechanical ventilation at onset of A. baumannii infection (OR 189.98, 95% CI 13.23–2,728.81; P<0.001) were identified as independent risk factors for infection-related 30-day mortality. In conclusion, the morbidity and mortality rates of A. baumannii infections were high in SOT recipients. Mechanical ventilation at onset of A. baumannii infection was associated with higher overall in-hospital mortality and infection-related mortality. For overall in-hospital mortality, liver or liver–kidney transplantation and late-onset A. baumannii infection, and for infection-related mortality, thrombocytopenia were also risk factors, respectively.

Distribution and resistance of pathogens in liver transplant recipients with Acinetobacter baumannii infection

BACKGROUND

Drug-resistant Acinetobacter baumannii has become a major problem in liver transplant recipients. The aim of this study was to investigate the clinical presentation, distribution, and drug susceptibility characteristics in liver recipients with A. baumannii infection.

METHODS

We retrospectively investigated 17 liver recipients who developed A. baumannii infection between January 1, 2007 and December 31, 2014. The distribution of A. baumannii and drug susceptibility characteristics were reviewed.

RESULTS

Infectious complications due to A. baumannii appeared in 17 liver recipients, with a total of 24 episodes. Approximately 63% (15/24) of A. baumannii infections occurred within 2 weeks after transplantation. The most common source of infection was multiple culture-positive sites (35.3%, n=6), followed by the intra-abdominal/biliary tract (23.5%, n=4) and lung (23.5%, n=4). Eight patients (47.1%) had a body temperature of 38°C or higher at the onset of A. baumannii infection. Nine, seven, and 12 recipients had a serum creatinine level of >1.5 mg/dL, a white blood cell count of >15,000/mm(3), and a platelet count of <50,000/mm(3), respectively. There were five (29.4%) cases of septic shock and eight (47.1%) deaths. The rate of antibiotic resistance of A. baumannii to ten of 12 antibiotics investigated was more than 60%. Among the 24 infections caused by A. baumannii, 75% were carbapenem-resistant. The rods were relatively sensitive to tigecycline and cefoperazone-sulbactam.

CONCLUSION

The clinical manifestations of A. baumannii infection included a high body temperature, a decreased platelet count, an elevated white blood cell count, and onset in the early period after transplantation as well as high mortality. The antibiotic resistance rate of A. baumannii was extremely high. Prevention measures and combination antibiotic therapy are needed to improve the outcomes of liver recipients with A. baumannii infections.

Distribution and resistance of pathogens in liver transplant recipients with Acinetobacter baumannii infection

Background

Drug-resistant Acinetobacter baumannii has become a major problem in liver transplant recipients. The aim of this study was to investigate the clinical presentation, distribution, and drug susceptibility characteristics in liver recipients with A. baumannii infection.

Methods

We retrospectively investigated 17 liver recipients who developed A. baumannii infection between January 1, 2007 and December 31, 2014. The distribution of A. baumannii and drug susceptibility characteristics were reviewed.

Results

Infectious complications due to A. baumannii appeared in 17 liver recipients, with a total of 24 episodes. Approximately 63% (15/24) of A. baumannii infections occurred within 2 weeks after transplantation. The most common source of infection was multiple culture-positive sites (35.3%, n=6), followed by the intra-abdominal/biliary tract (23.5%, n=4) and lung (23.5%, n=4). Eight patients (47.1%) had a body temperature of 38°C or higher at the onset of A. baumannii infection. Nine, seven, and 12 recipients had a serum creatinine level of >1.5 mg/dL, a white blood cell count of >15,000/mm³, and a platelet count of <50,000/mm³, respectively. There were five (29.4%) cases of septic shock and eight (47.1%) deaths. The rate of antibiotic resistance of A. baumannii to ten of 12 antibiotics investigated was more than 60%. Among the 24 infections caused by A. baumannii, 75% were carbapenem-resistant. The rods were relatively sensitive to tigecycline and cefoperazone-sulbactam.

Conclusion

The clinical manifestations of A. baumannii infection included a high body temperature, a decreased platelet count, an elevated white blood cell count, and onset in the early period after transplantation as well as high mortality. The antibiotic resistance rate of A. baumannii was extremely high. Prevention measures and combination antibiotic therapy are needed to improve the outcomes of liver recipients with A. baumannii infections.

Fulminant endocarditis and disseminated infection caused by carbapenem-resistant Acinetobacter baumannii in a renal-pancreas transplant recipient

Acinetobacter baumannii is an important cause of healthcare-associated infections, and is particularly problematic among patients who undergo organ transplantation. We describe a case of fulminant sepsis caused by carbapenem-resistant A. baumannii harboring the blaOXA-23 carbapenemase gene and belonging to international clone II. This isolate led to the death of a patient 6 days after simultaneous kidney-pancreas transplantation. Autopsy findings revealed acute mitral valve endocarditis, myocarditis, splenic and renal emboli, peritonitis, and pneumonia. This case highlights the severe nature of certain A. baumannii infections and the vulnerability of transplanted patients to the increasingly intractable "high-risk" clones of multidrug-resistant organisms.

Frequency and clinical outcomes of ESKAPE bacteremia in solid organ transplantation and the risk factors for mortality

BACKGROUND

Although bacteremias caused by the 6 ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species) have recently been highlighted as a serious complication in solid organ transplant (SOT), more information is urgently needed. We sought to investigate the frequency and clinical outcomes of ESKAPE bacteremia in SOT and determine the risk factors for mortality.

METHODS

A retrospective analysis of bacteremia after SOT was reviewed. Risk factors for mortality caused by ESKAPE bacteremia were identified.

RESULTS

Eighty-four episodes of bacteremia were caused by ESKAPE strains. Of these strains, 41 were caused by resistant ESKAPE (rESKAPE) organisms. The only factor for bacteremia-related mortality independently associated with ESKAPE was septic shock (odds ratio [OR] = 21.017, 95% confidence interval [CI] = 5.038-87.682, P < 0.001). The factors for bacteremia-related mortality independently associated with rESKAPE bacteremia were septic shock (OR = 16.558, 95% CI = 6.620-104.668, P = 0.003) and age ≥40 years (OR = 7.521, 95% CI = 1.196-47.292, P = 0.031).

CONCLUSIONS

To improve the outcomes of transplantation, more effective therapeutic treatments are of paramount importance when older SOT recipients with bacteremia due to ESKAPE/rESKAPE organisms present with septic shock.

Bacterial biliary tract infections in liver transplant recipients

PURPOSE OF REVIEW

The purpose of this study is to provide an overview of bacterial biliary tract infections in liver transplant recipients with a focus on pathogenesis and conservative treatment strategies.

RECENT FINDINGS

The development of interventional endoscopic and radiologic interventions has improved the outcome of conservative treatments for bile tract strictures and bilomas. However, recent data show an important rise of infections with multidrug-resistant (MDR) pathogens in liver transplant recipients.

SUMMARY

Both recurrent cholangitis and infected bilomas are bacterial biliary tract infections in liver transplant recipients responsible for significant morbidity and graft loss, which require a multidisciplinary approach. Risk factors for biliary tract strictures and bilomas formation have recently been identified. With the improved outcome of a conservative management including prolonged and/or recurrent antibiotic treatments, the risk of selecting resistant pathogens is increased. There is an urgent need to develop new strategies to reduce the risk of secondary infections by MDR isolates in liver transplant recipients.

Bacterial infection after liver transplantation

Infectious complications are major causes of morbidity and mortality after liver transplantation, despite recent advances in the transplant field. Bacteria, fungi, viruses and parasites can cause infection before and after transplantation. Among them, bacterial infections are predominant during the first two months post-transplantation and affect patient and graft survival. They might cause surgical site infections, including deep intra-abdominal infections, bacteremia, pneumonia, catheter-related infections and urinary tract infections. The risk factors for bacterial infections differ between the periods after transplant, and between centers. Recently, the emergence of multi-drug resistant bacteria is great concern in liver transplant (LT) patients. The instructive data about effects of infections with extended-spectrum beta lactamase producing bacteria, carbapenem-resistant gram-negative bacteria, and glycopeptide-resistant gram-positive bacteria were reported on a center-by-center basis. To prevent post-transplant bacterial infections, proper strategies need to be established based upon center-specific data and evidence from well-controlled studies. This article reviewed the recent epidemiological data, risk factors for each type of infections and important clinical issues in bacterial infection after LT.

Multidrug-resistant bacterial infections after liver transplantation: An ever-growing challenge

Bacterial infections are a leading cause of morbidity and mortality among solid organ transplant recipients. Over the last two decades, various multidrug-resistant (MDR) pathogens have emerged as relevant causes of infection in this population. Although this fact reflects the spread of MDR pathogens in health care facilities worldwide, several factors relating to the care of transplant donor candidates and recipients render these patients particularly prone to the acquisition of MDR bacteria and increase the likelihood of MDR infectious outbreaks in transplant units. The awareness of this high vulnerability of transplant recipients to infection leads to the more frequent use of broad-spectrum empiric antibiotic therapy, which further contributes to the selection of drug resistance. This vicious cycle is difficult to avoid and leads to a scenario of increased complexity and narrowed therapeutic options. Infection by MDR pathogens is more frequently associated with a failure to start appropriate empiric antimicrobial therapy. The lack of appropriate treatment may contribute to the high mortality occurring in transplant recipients with MDR infections. Furthermore, high therapeutic failure rates have been observed in patients infected with extensively-resistant pathogens, such as carbapenem-resistant Enterobacteriaceae, for which optimal treatment remains undefined. In such a context, the careful implementation of preventive strategies is of utmost importance to minimize the negative impact that MDR infections may have on the outcome of liver transplant recipients. This article reviews the current literature regarding the incidence and outcome of MDR infections in liver transplant recipients, and summarizes current preventive and therapeutic recommendations.

Strategies to reduce infectious complication using epidemiologic data analysis in liver transplant recipients

BACKGROUND

Infectious complications are major factors for morbidity and mortality in liver transplant recipients. To establish a proper strategy to reduce infectious complications, we analyzed epidemiologic and risk factors for post-transplant infections.

METHODS

We analyzed the medical records of 231 consecutive liver transplant recipients from December 2007 to November 2011, including at least 1-year follow up, for comparison with those from 1996 to 2005.

RESULTS

Among 231 patients, 126 (54.5%) experienced 244 infectious episodes, a rate of 1.05 per patient. Among overall mortality of 9.9% (23/231), infections were more prevalent (P = .04). Predominant infections were postoperative intra-abdominal problems (36.1%), peritonitis (15.2%), pneumonia (13.5%), bacteremia (4.1%), wound complications (1.6%), viral etiologies (18.0%), and other causes (11.5%). Causative organisms were bacterial (68.9%), viral (14.7%), fungal (7.0%), and unproven ones (9.4%). Multivariate analysis of risks for infection showed significant impacts of Model for End-stage Liver Disease score [P = .027; odds ratio (OR), 1.04], post-transplant biliary complications (P < .001; OR, 3.50), and rejection episodes (P = .023; OR, 3.39). Mortality was related to retransplantation (P = .003), post-transplant dialysis (P = .006), and infection (P = .056) upon univariate analysis, none of which were significant in multivariate analysis. Compared with data from the previous period, overall and infection-related mortality decreased from 24.5% to 9.9% and 52.9% to 26.1%, respectively. There were no significant changes in the types of infection or rate of drug-resistant bacteria, but candidal infections and cytomegalovirus reactivations were more prevalent.

CONCLUSION

Our data showed current perioperative antimicrobial regimens need not be changed: however, new strategies are needed to reduce infectious complications after liver transplantation, to reduce biliary complications and to properly manage rejection episodes.

Crystal structure of carbapenemase OXA-58 from Acinetobacter baumannii

Class D β-lactamases capable of hydrolyzing last-resort carbapenem antibiotics represent a major challenge for treatment of bacterial infections. Wide dissemination of these enzymes in Acinetobacter baumannii elevated this pathogen to the category of most deadly and difficult to treat. We present here the structure of the OXA-58 β-lactamase, a major class D carbapenemase of A. baumannii, determined to 1.30-Å resolution. Unlike two other Acinetobacter carbapenemases, OXA23 and OXA-24, the OXA-58 enzyme lacks the characteristic hydrophobic bridge over the active site, despite conservation of the residues which participate in its formation. The active-site residues in OXA-58 are spatially conserved in comparison to those in other class D β-lactamases. Lys86, which activates water molecules during the acylation and deacylation steps, is fully carboxylated in the OXA-58 structure. In the absence of a substrate, a water molecule is observed in the active site of the enzyme and is positioned in the pocket that is usually occupied by the 6α-hydroxyethyl moiety of carbapenems. A water molecule in this location would efficiently deacylate good substrates, such as the penicillins, but in the case of carbapenems, it would be expelled by the 6α-hydroxyethyl moiety of the antibiotics and a water from the surrounding medium would find its way to the vicinity of the carboxylated Lys86 to perform deacylation. Subtle differences in the position of this water in the acyl-enzyme complexes of class D β-lactamases could ultimately be responsible for differences in the catalytic efficiencies of these enzymes against last-resort carbapenem antibiotics.

Risk factors and outcomes of bacteremia caused by drug-resistant ESKAPE pathogens in solid-organ transplant recipients

BACKGROUND

Although infections due to the six ESKAPE pathogens have recently been identified as a serious emerging problem, information regarding bacteremia caused by these organisms in solid-organ transplant (SOT) recipients is lacking. We sought to determine the frequency, risk factors, and outcomes of bacteremia due to drug-resistant ESKAPE (rESKAPE) organisms in liver, kidney, and heart adult transplant recipients.

METHODS

All episodes of bacteremia prospectively documented in hospitalized SOT recipients from 2007 to 2012 were analyzed.

RESULTS

Of 276 episodes of bacteremia, 54 (19.6%) were due to rESKAPE strains (vancomycin-resistant Enterococcus faecium [0], methicillin-resistant Staphylococcus aureus [5], extended-spectrum β-lactamase-producing Klebsiella pneumoniae [10], carbapenem-resistant Acinetobacter baumannii [8], carbapenem- and quinolone-resistant Pseudomonas aeruginosa [26], and derepressed chromosomal β-lactam and extended-spectrum β-lactamase-producing Enterobacter species [5]). Factors independently associated with rESKAPE bacteremia were prior transplantation, septic shock, and prior antibiotic therapy. Patients with rESKAPE bacteremia more often received inappropriate empirical antibiotic therapy than the others (41% vs. 21.6%; P=0.01). Overall case-fatality rate (30 days) was higher in patients with rESKAPE bacteremia (35.2% vs. 14.4%; P=0.001).

CONCLUSIONS

Bacteremia due to rESKAPE pathogens is frequent in SOT recipients and causes significant morbidity and mortality. rESKAPE organisms should be considered when selecting empirical antibiotic therapy for hospitalized SOT recipients presenting with septic shock, particularly those with prior transplantation and antibiotic use.

Multidrug-resistant bacteria in organ transplantation: an emerging threat with limited therapeutic options

Multidrug-resistant organisms (MDROs) are an emerging threat in solid organ transplantation (SOT). The changing epidemiology of these MDROs is reviewed along with the growing evidence regarding risk factors and outcomes associated with both colonization and infection in SOT. The management of these infections is complicated by the lack of antimicrobial agents available to treat these infections, and only a handful of new agents, especially for the treatment of MDR GNR infections, are being evaluated in clinical trials. Due to the increased prevalence of MDROs and limited treatment options, as well as organ shortages, transplant candidacy and use of organs from donors with evidence of MDRO colonization and/or infection remain controversial. Increasing collaboration between transplant programs, individual practitioners, infection control programs, and researchers in antimicrobial development will be needed to face this challenge.

Epidemiology and clinical features of post-transplant bloodstream infection: an analysis of 222 consecutive liver transplant recipients

BACKGROUND

Bloodstream infection (BSI) is a significant cause of morbidity and mortality in liver transplant (LT) recipients. This study aimed to investigate the epidemiology and clinical features of post-transplant BSI in LT recipients.

MATERIALS AND METHODS

The microbiology, frequency, and outcome of post-transplant BSI in the first year after LT were retrospectively analyzed in 222 consecutive patients who had received liver transplants at a single center between 2005 and 2011. The risk factors for post-transplant BSI and death were evaluated.

RESULTS

During a 1-year period after LT, 112 episodes of BSI occurred in 64 of the 222 patients (28.8%). A total of 135 microorganisms were isolated from 112 BSI episodes including 18 polymicrobial episodes. The median time to BSI onset ranged from 8 days for Klebsiella pneumoniae to 101 days for enterococci, and the overall median for all microorganisms was 28 days. The most frequent pathogens were Enterobacteriaceae members (32.5%), enterococci (17.8%), yeasts (14.0%), Staphylococcus aureus (10.3%), and Acinetobacter baumannii (10.3%); most of them showed resistance to major antibiotics. The major sources of BSI were biliary tract (36.2%), abdominal and/or wound (28.1%), and intravascular catheter (18.5%) infections. The independent risk factors for post-transplant BSI were biliary complications (odds ratio [OR]: 2.91, 95% confidence interval [CI]: 1.29 to 6.59, P = 0.010) and longer hospitalization in the intensive care unit (OR: 1.04, 95% CI: 1.00 to 1.08, P < 0.001) after LT. BSI was an independent risk factor for death (hazard ratio [HR]: 3.92, 95% CI: 2.22 to 6.91, P < 0.001), with a poorer survival rate observed in patients with BSI than in those without BSI (1-year survival rate: 60.0% versus 89.5%, respectively, P < 0.001) after LT. The strongest predictors for death in patients with BSI were hepatocellular carcinoma (HR: 3.82, 95% CI: 1.57 to 9.32, P = 0.003), candidemia (HR: 3.71, 95% CI: 1.58 to 8.71, P = 0.003), polymicrobial bacteremia (HR: 3.18, 95% CI: 1.39 to 7.28, P = 0.006), and post-transplant hemodialysis (HR: 2.44, 95% CI: 1.02 to 5.84, P = 0.044).

CONCLUSIONS

BSI was a frequent post-transplant complication, and most of the causative pathogens were multi-drug resistant. Biliary complications and BSIs resulting from biliary infection are major problems for LT recipients. The prevention of BSI and biliary complications is critical in improving prognosis in liver transplant recipients.

Surgical site infections in liver transplant recipients in the model for end-stage liver disease era: an analysis of the epidemiology, risk factors, and outcomes

In recipients of liver transplantation (LT), surgical site infection (SSIs) are among the most common types of infection occurring in the first 60 days after LT. In 2007, the Model for End-Stage Liver Disease (MELD) scoring system was adopted as the basis for prioritizing organ allocation. Patients with higher MELD scores are at higher risk for developing SSIs as well as other health care-associated infections. However, there have been no studies comparing the incidence of SSIs in the pre-MELD era with the incidence in the period since its adoption. Therefore, the objectives of this study were to evaluate the incidence, etiology, epidemiology, and outcomes of post-LT SSIs in those 2 periods and to identify risk factors for SSIs. We evaluated all patients who underwent LT over a 10-year period (2002-2011). SSI cases were identified through active surveillance. The primary outcome measure was an SSI during the first 60 days after LT. Risk factors were analyzed via logistic regression, and 60-day survival rates were evaluated via Cox regression. We evaluated 543 patients who underwent LT 597 times. The SSI rates in the 2002-2006 and 2007-2011 periods were 30% and 24%, respectively (P = 0.21). We identified the following risk factors for SSIs: retransplantation, the transfusion of more than 2 U of blood during LT, dialysis, cold ischemia for >400 minutes, and a cytomegalovirus infection. The overall 60-day survival rate was 79%. Risk factors for 60-day mortality were retransplantation, dialysis, and a longer surgical time. The use of the MELD score modified the incidence and epidemiology of SSIs only during the first year after its adoption. Risks for SSIs were related more to intraoperative conditions and intercurrences after LT than to a patient's status before LT.

Infections after orthotopic liver transplantation in the intensive care unit

PURPOSE

The purpose of the study was to assess the characteristics and risk factors of infections in the early period after orthopic liver transplantation (OLT) among adult patients.

MATERIAL AND METHODS

We studied 75 patients who underwent OLT over 3 years from 2008 to 2010. We recorded all infections that developed during hospitalization in the intensive care unit (ICU) their outcomes, and the possible risk factors.

RESULTS

During the study period in 80 OLT we recorded 19 bloodstream infections (47.5%), 7 ventilator-associated pneumonias (VAP; 17.5%), and 14 intra-abdominal infections (35%). Among the 40 isolated microbes, 72.5% were Gram negative, 25% were Gram positive, and 2.5% were fungi. The median time to developing the infection was 4.95 days (range 2-10). Patients with infections showed longer durations of mechanical ventilation, longer lengths of ICU stay, and lower 1-year survivals.

Hand hygiene compliance in transplant and other special patient groups: an observational study

BACKGROUND

This study evaluates hand hygiene behavior of health care workers in a German university hospital stratified for treatment of special patient groups (eg, transplant patients).

METHODS

From 2008 to 2010, comprehensive education and training of all health care workers was implemented to improve hand hygiene compliance. Consumption rates of alcohol-based hand rub and gloves were collected and evaluated.

RESULTS

Of the 5,647 opportunities of hand disinfection evaluated, 1,607 occurred during care for transplant patients. To our knowledge, this is the largest survey of hand hygiene compliance in special patient groups on intensive care units in a university hospital in Germany. Health care workers on surgical intensive care units showed lower hand hygiene compliance compared with health care workers on other types of intensive care units. Compliance toward hand hygiene was significantly higher on hemato-oncologic and pediatric wards. In general, hand disinfection was performed significantly more frequently after an intervention than before (P < .05, 95% confidence interval: 1.24-1.84). Overall, there was no significant difference in hand hygiene compliance when caring for transplant patients or other patients (odds ratio, 1.16; 95% confidence interval: 0.95-1.42). Nurse's and physician's hand hygiene compliance improved because of education.

CONCLUSION

Hand hygiene compliance is not increased in the care for transplant patients (despite their predisposition for nosocomial infections) compared with other patients. Additional studies will be necessary to further investigate these findings.

Transplantation-associated long-term immunosuppression promotes oral colonization by potentially opportunistic pathogens without impacting other members of the salivary bacteriome

Solid-organ transplant recipients rely on pharmacological immunosuppression to prevent allograft rejection. The effect of such chronic immunosuppression on the microflora at mucosal surfaces is not known. We evaluated the salivary bacterial microbiome of 20 transplant recipients and 19 nonimmunosuppressed controls via 454 pyrosequencing of 16S rRNA gene amplicons. Alpha-diversity and global community structure did not differ between transplant and control subjects. However, principal coordinate analysis showed differences in community membership. Taxa more prevalent in transplant subjects included operational taxonomic units (OTUs) of potentially opportunistic Gammaproteobacteria such as Klebsiella pneumoniae, Pseudomonas fluorescens, Acinetobacter species, Vibrio species, Enterobacteriaceae species, and the genera Acinetobacter and Klebsiella. Transplant subjects also had increased proportions of Pseudomonas aeruginosa, Acinetobacter species, Enterobacteriaceae species, and Enterococcus faecalis, among other OTUs, while genera with increased proportions included Klebsiella, Acinetobacter, Staphylococcus, and Enterococcus. Furthermore, in transplant subjects, the dose of the immunosuppressant prednisone positively correlated with bacterial richness, while prednisone and mycophenolate mofetil doses positively correlated with the prevalence and proportions of transplant-associated taxa. Correlation network analysis of OTU relative abundance revealed a cluster containing potentially opportunistic pathogens as transplant associated. This cluster positively correlated with serum levels of C-reactive protein, suggesting a link between the resident flora at mucosal compartments and systemic inflammation. Network connectivity analysis revealed opportunistic pathogens as highly connected to each other and to common oral commensals, pointing to bacterial interactions that may influence colonization. This work demonstrates that immunosuppression aimed at limiting T-cell-mediated responses creates a more permissive oral environment for potentially opportunistic pathogens without affecting other members of the salivary bacteriome.

Epidemiology, clinical characteristics and outcomes of extensively drug-resistant Acinetobacter baumannii infections among solid organ transplant recipients

BACKGROUND

Extensively drug-resistant Acinetobacter baumannii (XDR-Ab) has emerged as a major nosocomial pathogen, but optimal treatment regimens are unknown. Although solid organ transplant (SOT) recipients are particularly susceptible to XDR-Ab infections, studies in this population are limited. Our objectives were to determine the epidemiology, clinical characteristics and outcomes of XDR-Ab infections among SOT patients.

METHODS

A retrospective study of SOT recipients at our center who were colonized or infected with XDR-Ab between November 2006 and December 2011 was conducted. Among infected patients, the primary outcome was survival at 28 days. Secondary outcomes included survival at 90 days and clinical success at 28 days, and XDR-Ab infection recurrence.

RESULTS

XDR-Ab was isolated from 69 SOT patients, of whom 41% (28) and 59% (41) were colonized and infected, respectively. Infections were significantly more common among cardiothoracic than abdominal transplant recipients (p=0.0004). Ninety-eight percent (40/41) of patients had respiratory tract infections, most commonly ventilator-associated pneumonia (VAP; 88% [36/41]). Survival rates at 28 and 90 days were 54% (22/41) and 46% (19/41), respectively. Treatment with a colistin-carbapenem regimen was an independent predictor of 28-day survival (p=0.01; odds ratio=7.88 [95% CI: 1.60-38.76]). Clinical success at 28 days was achieved in 49% (18/37) of patients who received antimicrobial therapy, but 44% (8/18) of successes were associated with infection recurrence within 3 months. Colistin resistance emerged in 18% (2/11) and 100% (3/3) of patients treated with colistin-carbapenem and colistin-tigecycline, respectively (p=0.03).

CONCLUSIONS

XDR-Ab causes VAP and other respiratory infections following SOT that are associated with significant recurrence and mortality rates. Cardiothoracic transplant recipients are at greatest risk. Results from this retrospective study suggest that colistin-carbapenem combinations may result in improved clinical responses and survival compared to other regimens and may also limit the emergence of colistin resistance.

The influence of carbapenem resistance on mortality in solid organ transplant recipients with Acinetobacter baumannii infection

Background

Infection with carbapenem-resistant Acinetobacter baumannii has been associated with high morbidity and mortality in solid organ transplant recipients. The main objective of this study was to assess the influence of carbapenem resistance and other potential risk factors on the outcome of A. baumannii infection after kidney and liver transplantation.

Methods

Retrospective study of a case series of A. baumannii infection among liver and renal transplant recipients. The primary outcome was death associated with A. baumannii infection. Multivariate logistic regression was used to assess the influence of carbapenem resistance and other covariates on the outcome.

Results

Forty-nine cases of A. baumannii infection affecting 24 kidney and 25 liver transplant recipients were studied. Eighteen cases (37%) were caused by carbapenem-resistant isolates. There were 17 (35%) deaths associated with A. baumannii infection. In unadjusted analysis, liver transplantation (p = 0.003), acquisition in intensive care unit (p = 0.001), extra-urinary site of infection (p < 0.001), mechanical ventilation (p = 0.001), use of central venous catheter (p = 0.008) and presentation with septic shock (p = 0.02) were significantly related to a higher risk of mortality associated with A. baumannii infection. The number of deaths associated with A. baumannii infection was higher among patients infected with carbapenem-resistant isolates, but the difference was not significant (p = 0.28). In multivariate analysis, the risk of A. baumannii-associated mortality was higher in patients with infection acquired in the intensive care unit (odds ratio [OR] = 34.8, p = 0.01) and on mechanical ventilation (OR = 15.2, p = 0.04). Appropriate empiric antimicrobial therapy was associated with significantly lower mortality (OR = 0.04, p = 0.03), but carbapenem resistance had no impact on it (OR = 0.73, p = 0.70).

Conclusion

These findings suggest that A. baumannii-associated mortality among liver and kidney transplant recipients is influenced by baseline clinical severity and by the early start of appropriate therapy, but not by carbapenem resistance.

Perioperative bacterial infections in deceased donor and living donor liver transplant recipients

BACKGROUND

Deceased donor (DDLT) and living donor (LDLT) liver transplant (LT) is in vogue in several centers in India. Most centers are resorting to LDLT as a preferred surgery due to shortage of deceased donor liver. The risk of infection and its effect on survival in both groups of recipients from the Indian subcontinent are not known. The study was conducted to compare the bacterial infection rates among LDLT and DDLT recipients and their impact on survival at a tertiary referral center.

METHODS

Retrospective data on 67 LT recipients were reviewed. Data on pre-, per-, and postoperative bacterial infection rates and the common isolates were obtained.

RESULTS

Thirty-five patients had LDLT and 32 had DDLT. The prevalence of pre-operative bacterial infection and the isolates was similar in both groups. The perioperative bacterial infection rates were significantly higher in DDLT recipients (P < 0.01) (relative risk: 1.44 95% confidence interval 1.04-1.9). In both LDLT and DDLT, the common source was urinary tract followed by bloodstream infection. The common bacterial isolates in either transplant were Klebsiella followed by Escherichia coli, Pseudomonas spp. and nonfermenting gram-negative bacteria. Six patients (four LDLT; two DDLT) were treated for tuberculosis. Among the risk factors, cold ischemic time, and duration of stay in the intensive care unit was significantly higher for DDLT (p < 0.01). The death rates were not significantly different in the two groups. However, the odds for death were significantly high at 26.8 (p < 0.05) for postoperative bacterial infection and 1.8 (p < 0.001) for past alcohol.

CONCLUSION

Liver transplant recipients are at high-risk for bacterial infection irrespective of type of transplant, more so in DDLT.

Risk factors and antibiotic resistance of pneumonia caused by multidrug resistant Acinetobacter baumannii in pediatric intensive care unit

BACKGROUND

With beta-lactam drugs and immunosuppressants widely used, the infection caused by Acinetobacter baumannii (Ab) has become more and more serious with multidrug resistant Acinetobacter baumannii (MDRAb) emerging and worsening rapidly. Compared with other patients, the incidence and multidrug resistance of MDRAb are higher in children in pediatric intensive care unit (PICU) because of immune deficiency, severe basic diseases, prolonged hospitalization and invasive operations. Hence it is significant to study the epidemiology and changes of antibacterial susceptibility in order to reduce the incidence of MDRAb in children.

METHODS

A total 115 patients with MDRAb pneumonia and 45 patients with negative MDRAb (NMDRAb) pneumonia who had been treated from January 2009 to August 2011 were studied retrospectively at the PICU of Wuhan Children's Hospital. Clinical data were analyzed with univariate and multivariate Logistic regression.

RESULTS

In 176 clinical strains of Acinetobacter baumannii isolated, there were 128 strains of MDRAb, accounting for 72.73%. Drug susceptibility tests showed that the resistance rates of β-lactam antibiotics were more than 70% except for cefoperazone sulbactam. The rates to carbapenems were higher than 90%. They were significantly higher than those of NMDRAb. Amikacin, levofloxacin, ciprofloxacin and minocycline had the lowest drug-resistance rates (<20%). Multivariate Logistic regression revealed that ICU stay, the time of mechanical ventilation, anemia, hypoproteinemia and the use of carbapenems were independent risk factors for MDRAb pneumonia.

CONCLUSIONS

MDRAb is an important opportunistic pathogen to pneumonia in PICU, and its drug-resistance is severe. It increases significantly the mortality of patients. It is important to take the effective prevention measures for controlling it.