Mortality associated with Acinetobacter baumannii infections experienced by lung transplant recipients

Donor respiratory multidrug-resistant bacteria and lung transplantation outcomes

RATIONALE

Respiratory culture screening is mandatory for all potential lung transplant donors. There is limited evidence on the significance of donor multidrug-resistant (MDR) bacteria on transplant outcomes. Establishing the safety of allografts colonized with MDR bacteria has implications for widening an already limited donor pool.

OBJECTIVES

We aimed to describe the prevalence of respiratory MDR bacteria among our donor population and to test for associations with posttransplant outcomes.

METHODS

This retrospective observational study included all adult patients who underwent lung-only transplantation for the first time at King Faisal Specialist Hospital & Research Centre in Riyadh from January 2015 through May 2022. The study evaluated donor bronchoalveolar lavage and bronchial swab cultures.

MAIN RESULTS

Sixty-seven of 181 donors (37%) had respiratory MDR bacteria, most commonly MDR Acinetobacter baumannii (n = 24), methicillin-resistant Staphylococcus aureus (n = 18), MDR Klebsiella pneumoniae (n = 8), MDR Pseudomonas aeruginosa (n = 7), and Stenotrophomonas maltophilia (n = 6). Donor respiratory MDR bacteria were not significantly associated with allograft survival or chronic lung allograft dysfunction (CLAD) in adjusted hazard models. Sensitivity analyses revealed an increased risk for 90-day mortality among recipients of allografts with MDR Klebsiella pneumoniae (n = 6 with strains resistant to a carbapenem and n = 2 resistant to a third-generation cephalosporin only) compared to those receiving culture-negative allografts (25.0% versus 11.1%, p = 0.04). MDR Klebsiella pneumoniae (aHR 3.31, 95%CI 0.95-11.56) and Stenotrophomonas maltophilia (aHR 5.35, 95%CI 1.26-22.77) were associated with an increased risk for CLAD compared to negative cultures.

CONCLUSION

Our data suggest the potential safety of using lung allografts with MDR bacteria in the setting of appropriate prophylaxis; however, caution should be exercised in the case of MDR Klebsiella pneumoniae.

Gearing up for battle: Harnessing adaptive T cell immunity against gram-negative pneumonia

Pneumonia is one of the leading causes of morbidity and mortality worldwide and Gram-negative bacteria are a major cause of severe pneumonia. Despite advances in diagnosis and treatment, the rise of multidrug-resistant organisms and hypervirulent strains demonstrates that there will continue to be challenges with traditional treatment strategies using antibiotics. Hence, an alternative approach is to focus on the disease tolerance components that mediate immune resistance and enhance tissue resilience. Adaptive immunity plays a pivotal role in modulating these processes, thus affecting the incidence and severity of pneumonia. In this review, we focus on the adaptive T cell responses to pneumonia induced by Klebsiella pneumoniae, Pseudomonas aeruginosa, and Acinetobacter baumannii. We highlight key factors in these responses that have potential for therapeutic targeting, as well as the gaps in current knowledge to be focused on in future work.

Patients with transplantation have reduced mortality in bacteraemia: Analysis of data from a randomised trial

OBJECTIVES

Infection remains a major complication of organ transplantation. Paradoxically, epidemiological studies suggest better survival from serious infection. We analysed the relationship between organ transplantation and short -term mortality of patients with bloodstream infection.

METHODS

Data on transplantation status was extracted from a large prospective, multi-centre clinical trial in bloodstream infection. Logistic regression for 28-day mortality was performed on the whole cohort and a propensity-matched cohort (3:1). Infective pathogen, focus of infection, and clinical variables were included in the model. Mediation analysis was performed on clinical variables to explore causation.

RESULTS

4,178 participants were included in the full cohort, with 868 in the matched cohort, of which 217 received an organ transplant. Haematopoietic stem cell transplants (HSCT) were the most common transplant (n = 99), followed by kidney (n = 70). The most common pathogens were staphylococci and Enterobacterales. Transplantation status was associated with a reduced mortality in both the whole (Odds Ratio, OR 0.53; 95% CI 0.28, 0.77) and matched (OR 0.55, 95% CI 0.34, 0.90) cohort, while steroid use was robustly associated with increased mortality OR 4.4 (95% CI 3.12, 6.20) in the whole cohort and OR 5.24 (95% CI 2.79, 9.84) in the matched cohort. There was no interaction between steroid use and transplant status, so transplant patients on steroids generally had increased mortality relative to those without either.

CONCLUSIONS

Organ transplantation is associated with a near halving of short term mortality in bloodstream infection, including a cohort matched for comorbidities, infective pathogen and focus. Steroid usage is associated with increased mortality regardless of transplant status. Understanding the mechanism and causation of this mortality benefit should be a focus of future research.

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.

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.

Acinetobacter baumannii and A. pittii clinical isolates lack adherence and cytotoxicity to lung epithelial cells in vitro

The molecular and genetic basis of Acinetobacter baumannii and Acinetobacter pittii virulence remains poorly understood, and there is still lack of knowledge in host cell response to these bacteria. In this study, we have used eleven clinical Acinetobacter strains (A. baumannii n = 5; A. pittii n = 6) to unravel bacterial adherence, invasion and cytotoxicity to human lung epithelial cells. Our results showed that adherence to epithelial cells by Acinetobacter strains is scarce and cellular invasion was not truly detected. In addition, all Acinetobacter strains failed to induce any cytotoxic effect on A549 cells.

Inpatient Mortality Among Solid Organ Transplant Recipients Hospitalized for Sepsis and Severe Sepsis

BACKGROUND

Solid organ transplant (SOT) recipients are at elevated risk of sepsis. The impact of SOT on outcomes following sepsis is unclear.

METHODS

We performed a retrospective cohort study using data from University HealthSystem Consortium, a consortium of academic medical center affiliates. We examined the association between SOT and mortality among patients hospitalized with severe sepsis or explicitly coded sepsis in 2012-2014. We used International Classification of Diseases, Ninth Revision (ICD-9) codes to identify severe sepsis, explicitly coded sepsis, and SOT (kidney, liver, heart, lung, pancreas, or intestine transplants). We fit random-intercept logistic regression models to account for clustering by hospital.

RESULTS

There were 903 816 severe sepsis hospitalizations (39 618 [4.4%] with SOT) and 410 623 sepsis hospitalizations (14 526 [3.9%] with SOT) in 250 hospitals. SOT recipients were younger and more likely to be insured by Medicare than those without SOT. Among hospitalizations for severe sepsis and sepsis, in-hospital mortality was lower among those with vs those without SOT (5.5% vs 9.4% for severe sepsis; 8.7% vs 12.7% for sepsis). After adjustment, the odds ratio for mortality comparing SOT patients vs non-SOT was 0.83 (95% confidence interval [CI], .79-.87) for severe sepsis and 0.78 (95% CI, .73-.84) for sepsis. Compared to non-SOT patients, kidney, liver, and co-transplant (kidney-pancreas/kidney-liver) recipients demonstrated lower mortality. No association was present for heart transplant, and lung transplant was associated with higher mortality.

CONCLUSIONS

Among patients hospitalized for severe sepsis or sepsis, those with SOT had lower inpatient mortality than those without SOT. Identifying the specific strategies employed for populations with improved mortality could inform best practices for sepsis among SOT and non-SOT populations.

Lung Transplantation in a Multidrug-Resistant Gram-Negative Acinetobacter Baumannii-Colonized Patient: A Case Report

Colonization or infection with various pathogens is frequently found in patients listed for lung transplantation. We describe a case of a 50-year-old woman with α-1-antitrypsin deficiency, which was listed for double-lung transplantation, with multidrug-resistant gram-negative Acinetobacter baumannii (MRGN4-Ab) skin colonization. Transplantation was successfully performed. Colistin (Polymyxine E) was administered intravenously and through inhalation in the first month. MRGN4-Ab was still detectable in skin swabs without evidence of infection. After good recovery and clinical inapparence, the patient was discharged 2 months after transplantation.

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.

Multidrug-resistant Acinetobacter baumannii infections in lung transplant patients in the cardiothoracic intensive care unit

BACKGROUND

Multidrug-resistant (MDR) gram-negative bacteria are a growing threat to solid organ transplantation (SOT) patients in the intensive care unit (ICU). We aimed to examine the mortality rates of gram-negative MDR bacterial infection in SOT patients compared with patient population undergoing other cardiothoracic surgeries and hospitalized under similar ICU conditions.

METHODS

A retrospective study from a single medical center, including patients with MDR Acinetobacter baumannii and carbapenem-resistant Klebsiella pneumoniae infection, hospitalized in the cardiothoracic ICU. Data were collected from computerized databases, and data were verified using the hospitalization files. Microbiological data were provided by the microbiology laboratory.

RESULTS

During the study period, 205 SOT patients and 5031 other patients were hospitalized in the cardiothoracic ICU. Active infection with gram-negative MDR bacteria was identified in 147 patients, of which 37 underwent SOT (18% of total transplant recipients) and 110 underwent another cardiothoracic surgery (2% of total patients who are not transplant recipients). Mortality rates were high among both groups of patients, with no significant difference between them.

CONCLUSIONS

Infection with resistant bacteria is more prevalent among patients following SOT compared with patients following other cardiothoracic surgeries. Mortality is high in all patients regardless of the immunocompromised condition.

Treatment of MDR-Gram negative infections in the 21st century: a never ending threat for clinicians

The spread of antimicrobial resistance among Gram negative bacteria has dramatically reduced the current therapeutic opportunities and hampered the perspectives of drug discovery pipeline. Several unmet needs concerning the optimal therapeutic approaches to severe infections caused by the leading multi-drug-resistant GNB are still unresolved, mainly in relationship with the difficulty in the design of prospective comparative studies. Therefore a perspective of how the main resistance patterns and the related infections can be managed in the absence of more definitive data is mandatory.

Recipient-born bloodstream infection due to extensively drug-resistant Acinetobacter baumannii after emergency heart transplant: report of a case and review of the literature

Infections due to drug-resistant Gram-negative rods are an emerging risk factor for increased mortality after solid organ transplant. Extensively drug-resistant (XDR) Acinetobacter baumannii (Acb) is a major threat in several critical care settings. The limited available data on the outcome of XDR Acb infections in organ transplant recipients mostly comes from cases of donor-derived infections. However, recipients of life-saving organs are often critically ill patients, staying long term in intensive care units, and therefore at high risk for nosocomial infections. In this report, we describe our experience with the exceedingly complex management of a recipient-born XDR Acb bloodstream infection clinically ensued shortly after heart transplant. We also review the current literature on this mounting issue relevant for intensive care, transplant medicine and infectious diseases.

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.

Nosocomial bloodstream infections in a nationwide study: comparison between solid organ transplant patients and the general population

BACKGROUND

The incidence of bloodstream infection (BSI) varies according to the transplanted organ. Mortality can be as high as 24%, with a significant impact on graft survival. Transplantation is a risk factor for multidrug-resistant (MDR) organisms, but comparison with a non-transplanted population in a single large cohort has not been described.

METHODS

This is a prospective nationwide study (16 centers) reporting data on 2364 monomicrobial nosocomial BSIs, comparing 83 episodes in solid organ transplant patients with 2447 BSIs occurring in the general hospital population.

RESULTS

The prevalence of groups of infecting organisms (gram-positive, gram-negative, and fungi) was similar between transplant patients and the general population and a similar crude mortality rate was observed (34.9% in transplant vs. 43.3% in non-transplant patients). Staphylococcus aureus was the single most frequently isolated organism in both groups, and Acinetobacter species was more frequently isolated in the general population. Regarding MDR organisms, Klebsiella species, and Enterobacter species resistant to cefepime, as well as Acinetobacter species resistant to meropenem, were significantly more frequent in transplant patients.

CONCLUSION

Antimicrobial resistance is higher, particularly among gram-negative bacteria in the transplant population, although the overall mortality rate between transplant and non-transplant patients with nosocomial BSI is similar.

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.

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.

Impact of multidrug-resistant organisms on patients considered for lung transplantation

Infections with multidrug-resistant organisms are a growing problem in lung transplant recipients. Carriage of drug-resistant bacteria and fungi before transplantation is an important risk factor for such infections. In that regard Pseudomonas aeruginosa and species of Burkholderia, Acinetobacter, non-tuberculous mycobacteria and Scedosporium are particularly important. An understanding of the impact of these organisms is essential to the evaluation of lung transplant candidates. The microbiology, epidemiology, clinical manifestations, and approach to these pathogens before transplant are reviewed in this article.

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.

High mortality associated with Acinetobacter species infection in liver transplant patients

BACKGROUND

Acinetobacter species have become increasingly important nosocomial pathogens worldwide and can result in a wide range of infections, including bacteremia, pneumonia, urinary tract infection, peritonitis, among others. The aim of this study was to investigate clinical characteristics, mortality, and outcomes among liver transplant recipients with Acinetobacter species infections.

METHODS

We retrospectively analyzed 451 subjects who had undergone living donor liver transplantations between January 2001 and May 2010. Pandrug-resistant (PDR) Acinetobacter species were defined as resistant to all commercially available antibiotics except colistin.

RESULTS

Infectious complications due to Acinetobacter species appeared in 26 patients (5.8%) with a total of 37 episodes. Of the species identified, 34 were Acinetobacter baumannii and 3 Acinetobacter Iwoffiii. The presumed sources of infection were the biliary tract (n = 21, 56.8%), lung (n = 7, 18.9%), intra-abdomen (n = 6, 16.2%), catheter (n = 2, 5.4%), and urinary tract (n = 1, 3.6%). Among the 37 Acinetobacter species, 75.7% (28/37) were PDR species. Age, duration of intensive care unit stay, Child-Pugh score, and Model for End-stage Liver Disease score were not significant risk factors for Acinetobacter species infection. However, the overall mortality among patients with Acinetobacter species infections was 50% (13/26), which was significantly higher than that among those free of infection (50% vs 11.5%, P < .05). Multivariate analysis using a Cox regression model showed that inappropriate antimicrobial treatment was a significant independent risk factor for mortality among patients with Acinetobacter species infections (hazard Ratio = 4.19, 95% confidence interval 1.1-18.7; P = .06).

CONCLUSION

Patients with Acinetobacter species infections after liver transplantation show a significantly worse prognosis. PDR Acinetobacter species have been a major problem in our center.

Severe infection in a lung transplant recipient caused by donor-transmitted carbapenem-resistant Acinetobacter baumannii

We describe a case of proven donor transmission of carbapenem-resistant Acinetobacter baumannii, which resulted in severe infectious complications after lung transplantation. A single bla(OXA-23) positive strain, belonging to a new multilocus sequence type (ST231), was isolated from donor and recipient, who died 65 days after transplantation. This report highlights the current challenges associated with the potential transmission of multidrug-resistant infections through organ transplantation.