Seasonal pattern of early mortality and infectious complications in liver transplant recipients

Seasonal variation of cytomegalovirus disease in kidney transplant recipients

PURPOSE

Studies conducted in the northern United States found cytomegalovirus (CMV) disease after liver transplantation follows a seasonal pattern, with increased incidence in fall and winter. This has not been evaluated in kidney transplant recipients. Improved understanding of CMV seasonality may help guide use of preventative therapies.

METHODS

We evaluated adult patients receiving a kidney transplant at our center in Wisconsin from January 1, 1995 to December 31, 2018. CMV event was defined as quantifiable viral replication with clinical signs or symptoms suspicious for CMV per current consensus recommendations. Seasons were divided as follows: winter (December-February), spring (March-May), summer (June-August), and fall (September-November). The primary objective was to evaluate the annual distribution of CMV disease and determine whether this differed by season.

RESULTS

There were 6151 kidney transplants in the study period. A total of 913 patients had 1492 episodes of CMV. Median time from transplant to first detection was 5.51 months (interquartile range [IQR] 2.87-11.7). The observed overall incidence exceeded the expected incidence in winter (+.7%), spring (+5.5%), and fall (+3.4%) and was less than expected in summer (-9.5%) (p = .18). The incidence of CMV during summer, however, was 21% less than expected (p = .001) in recipients who were CMV positive (R+) at the time of transplantation. No such difference was observed in CMV negative recipients (R-; p = .58).

CONCLUSION

CMV after kidney transplant appears to be less common during the summer season in patients who were R+ at transplant but does not follow seasonal variation in R-. Reasons for this are unclear but are likely related to CMV-specific cell-mediated immunity. These findings may have clinical implications, particularly the use of non-pharmacologic strategies to improve response to antiviral therapy.

What Influence Does the Time of Year Have on Postoperative Complications Following Total Knee Arthroplasty?

BACKGROUND

The time of year might influence the occurrence of surgical complications. Therefore, this study investigated correlations between the time-of-year and 30-day postoperative complication rates following primary total knee arthroplasty (TKA). Specifically, we determined (1) postoperative complication rates across all quarters; and (2) time-of-year influence on complications using univariate and multivariate regression analyses.

METHODS

CPT code 27447 identified 147,473 TKAs from the NSQIP database. Readmissions, reoperations, as well as medical and surgical complications occurring within 30 postoperative days were assessed. All TKAs were divided into 4 cohorts based on the quarter-of-the-year (Q1-Q4) during which the surgery was performed. Chi-Square, ANOVA, linear regression, as well as univariate and multivariate analyses were performed to compare complication rates. A P < .05 was set for statistical significance.

RESULTS

Q3 had a higher risk of superficial infection when compared to Q1 (OR 1.37; 95% CI 1.12-1.69; P = .002). There was a lower risk of pneumonia between Q2 and Q1 (OR: 0.7; 95% CI 0.54-0.90; P = .007) as well as Q4 and Q1 (OR 0.76; 95% CI 0.6-0.96; P = .017). Blood transfusion was lower in Q2, Q3, and Q4 compared to Q1 (P = .02, P < .001, and P < .001).

CONCLUSION

This study provides a baseline analysis correlating the time of year and outcomes of TKA. However, since seasonality and weather can vary greatly in the United States by geographic region and time of year, future studies should be performed at a more granular level using hospital-specific data correlating weather and region to TKA outcomes.

Seasonal changes of lower respiratory tract infections in lung transplant recipients during the first post-transplant year: The Hungarian experience

BACKGROUND

After lung transplantation (LuTX) a high level of immunosuppression is needed to prevent rejection of the graft. Together with earlier colonization by pathogens, immunosuppression makes recipients more susceptible to infections, especially during the first postoperative year. As seasonality of lower respiratory tract infections (LRTI) is well-known in chronic lung diseases, we assessed seasonal changes of pathogen spectrum and number of infections in the first postoperative year in LuTX recipients.

METHODS

LRTI were analyzed in 28 Hungarian adult LuTX patients. Incidence and spectrum of microorganism causing LRTI were evaluated according to post-transplant time and seasonal temperature and humidity changes.

RESULTS

A total of 69 cases of LRTI were registered (average: 1.9 cases/patient; range: 0-14). Gram-negative=59, gram-positive=26, and fungal=31 pathogens were detected, with polymicrobial samples in 46% of all cases. Increased number of LRTI was observed in the cold season (1.68±1.54 vs 0.79±0.92 case/month/patient, P<.01) and significant negative correlations were identified between the incidence of polymicrobial and bacterial infections and temperature (r² =0.1535, P<.05, r² =0.3144, P<.01, respectively). In addition, positive correlation was observed between polymicrobial infections and humidity (r² =0.1403, P<.05). Higher incidence of LRTI was also noted in the cold season, when accounting for the differences in immunosuppression.

CONCLUSION

Seasons influenced the incidence of LRTI in the first postoperative year in LuTX recipients. More intensive vigilance for possible gram-negative and polymicrobial infections is needed in these patients in cold and wet seasons in the continental climate zone, regardless of underlying disease.

To everything there is a season: impact of seasonal change on admissions, acuity of injury, length of stay, throughput, and charges at an accredited, regional burn center

PURPOSE

Although previous studies have investigated the impact of weather and temporal factors on incidence of trauma admissions, there is a paucity of data describing the effect of seasonal change on burn injury. The purpose of this study was to examine the impact of the changing seasons on admissions to and resource utilization at an accredited burn center, with the goal of optimizing patient throughput and matching supply with demand.

METHODS

We performed a retrospective review of all burn admissions to an accredited, regional burn center, from Summer 2009 through Spring 2010. Patients were segregated into the seasonal cohorts of Summer, Fall, Winter, and Spring, based on admission date. Patient demographics included age, gender, mechanism of injury, and total body surface area (TBSA) injured. Main outcome measures included length of intensive care unit (ICU) stay, length of stay (LOS), and hospital charges, which served as a proxy for resource utilization (nursing, wound, and critical care; access to operating room (OR); inpatient rehabilitation). Groups were compared by T tests, with statistical significance assigned to P values <0.05.

RESULTS

Seven hundred thirty patients were admitted to the burn center during this annual period, with a mean age of 31.6 years and a TBSA of 8.9%. Although Spring had the greatest the number of admissions at 219 (30%), patients from Summer and Winter had the largest burns, longest length of ICU and hospital stays, and highest hospital charges (P < 0.05). Furthermore, variability of these parameters, as measured by standard deviation, was greatest during Summer and Winter, serving to reduce throughput via uneven demand on resources. Highest throughput occurred during the Spring, which had the highest admission-to-LOS ratio. No differences were observed in age, gender, and incidence of electrical injuries, across the 4 seasons.

CONCLUSIONS

Summer and winter were the peak seasons of resource utilization at our burn center, in terms of length and variability of ICU and hospital stays, as well as total hospital charges. Such seasonal change may be related to acuity of burn injury but not number of burn admissions. To improve operational efficiency and maximize patient throughput, resource allocation should be structured to anticipate seasonal changes, so that supply of services matches demand.

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.

Features of immune senescence in liver transplant recipients with established grafts

Immune senescence is the normal process whereby the human immune system ages, but becomes less effective. We investigated whether liver transplant recipients have features of immune senescence. Lymphocytes from 97 liver transplant recipients with established grafts and 41 age-matched and sex-matched controls were subjected to an 8-color flow cytometry assay that measured expression of killer cell lectin-like receptor subfamily G member 1, cluster of differentiation 127 (CD127), CD45RO, CD27, CD28, CD4, CD8, and CD57. Lymphocyte telomere length was assessed by flow-fluorescence in situ hybridization. Cases were compared with controls for each marker of immune senescence using a Mann-Whitney U test. For liver transplant recipients, linear regression analyses identified associations between markers of immune senescence and clinical or demographic characteristics. Lymphocytes from liver transplant recipients expressed more phenotypic markers of maturity than did lymphocytes from controls. Lymphocyte telomeres were shorter in liver transplant recipients than in controls. Age, hepatocellular carcinoma at transplantation, and skin malignancy developing after transplantation were associated independently with shortened lymphocyte telomeres. Increasing age and previous cytomegalovirus infection were associated independently with phenotypic markers of lymphocyte maturity. Thus, lymphocytes from liver transplant recipients are older "biologically" than lymphocytes from age-matched and sex-matched controls. Hepatocellular carcinoma at transplantation, subsequent skin malignancy, and previous cytomegalovirus infection are associated with lymphocyte senescence in liver transplant recipients.

Early intra-abdominal infections associated with orthotopic liver transplantation

BACKGROUND

Postoperative infections remain a significant problem among liver transplant recipients (LTRs). An early cause of morbidity after liver transplantation is intra-abdominal infection (IAI) about which there are limited data.

METHODS

We report a retrospective review of 169 adult LTRs from January 1, 2002 to June 9, 2006, comparing those who developed early postoperative IAI (peritonitis, biliary tract infection, abdominal abscess, or enteritis) with those who did not to identify clinical features and risk factors, analyze epidemiology, and assess graft and patient survival.

RESULTS

Sixty-eight patients (40%) had 104 infections, with 148 pathogens isolated. Leukocytosis (53%) and fever (34%) were the most common clinical features, and peritonitis (43%) was the most common manifestation. Enterococcus spp., the most frequent single pathogens, comprised 26% of organisms cultured. There were significant associations of IAI with pretransplant ascites (P=0.002), posttransplant dialysis (P=0.015), and non-IAI surgical complications (P<0.001). There was a trend toward graft failure in patients with IAI (P=0.051) but increased mortality was not associated with IAI. Use of pretransplant antibiotics was significantly associated with development of multiple drug-resistant organisms in IAI (P=0.032).

CONCLUSION

IAI occurred at a relatively high rate in the early postoperative period, and fever was not a major indicator. In patients receiving antibiotics within 2 weeks before transplantation, multiple drug-resistant organisms often caused IAI. In addition, the presence of pretransplant ascites, posttransplant dialysis, and wound infection or reoperation after transplant should alert one to the increased risk of IAI in LTRs.

Effect of seasonal variation on the clinical course of chronic hepatitis B

BACKGROUND

Seasonal variation in immunity has been found in healthy individuals and in association with some diseases. It is still unknown whether seasonal variation affects the clinical course of chronic hepatitis B. Our aim in this study was to explore the effect of seasonal variation on the clinical course of chronic hepatitis B.

METHODS

The flare and remission time of chronic hepatitis B were observed in patients with hepatitis B virus (HBV) infection. All patients enrolled were followed up at least every 3 months for a mean follow-up time of 24.0 (range, 12-60) months. Seasonal decomposition was employed to analyze the relationship between seasonal variation and flares, remission, and hepatitis B e antigen (HBeAg) seroconversion in chronic hepatitis B patients during follow-up.

RESULTS

A total of 2238 patients were observed in our study. Flare and HBeAg seroconversion were seldom seen in 1076 patients (48.08%) with alanine aminotransferase (ALT) levels of less than 2.0 x upper limit of normal (ULN) during follow-up (mean, 36 months). The remaining 1162 patients (51.92%) (766, HBeAg positive; 387 anti-HBeAg positive; 9 negative for both HBeAg and anti-HBeAg) with ALT levels >or=2.0 x ULN were followed longitudinally for 12 months to judge flare, remission, and HBeAg seroconversion. Flare, remission, and HBeAg seroconversion in patients with ALT levels >or=2.0 x ULN showed clear seasonal patterns (P < 0.001), with high peaks during spring, summer, and summer, respectively. An autocorrelation correlogram showed that flares, remission, and HBeAg seroconversion occurred with distinct periodicity in winter, spring, summer, and autumn.

CONCLUSIONS

Seasonal variation might affect the clinical course of chronic hepatitis B. The role of seasonal triggering factors should be further investigated.

Intensive Care Complications in Liver and Multivisceral Transplantation

The complications concerning liver and intestinal transplant surgery have relevance for the field of intensive care because they share some characteristics with those following complex long-term surgery. Thus, in this article we shall try to describe complications that are specific to liver and multivisceral transplants. A review of the existing literature on this topic reveals a large number of studies dedicated to early as well as late surgical complications, and immunosuppressive treatment, while there are far fewer contributions describing complications exclusively concerning intensive care. We shall thus attempt to focus on certain aspects where, besides the literature data, we have personal experience. In particular we want to underline the implications of failure in the functional recovery of the graft; alterations in water, electrolyte, and glycemic balance; as well as neurological, respiratory, renal, nutritional, and infective complications.

Interactions between viruses in transplant recipients

Viral coinfections may modulate disease expression, enhance pathogenicity, and lead to greater cumulative immunosuppression in the host. The pathophysiological basis of these may be direct virus-virus interactions, effect of cohabitating viruses on host cell function, or impaired host immune responses. The interrelationship between viral pathogens has become increasingly more relevant and its scope wider as new or previously unrecognized viruses continue to emerge as pathogens in transplant recipients. The pathways and mediators that modulate biological activity represent potential targets for immunomodulatory interventions as adjunctive therapies for transplant recipients.

Genetic control of innate immune responses against cytomegalovirus: MCMV meets its match

Cytomegalovirus (CMV) is a widespread pathogen that is responsible for severe disease in immunocompromised individuals and probably, associated with vascular disease in the general population. There is increasing evidence that cells of the innate immune system play a key role in controlling this important pathogen. This is particularly evident in the experimental murine CMV (MCMV) model of infection which has revealed an important role for natural killer (NK) cells in controlling early viral replication after infection with MCMV. In this model, different strains of inbred mice exhibit striking differences in their level of susceptibility to MCMV infection. Genetic studies, performed almost 10 years ago, revealed that this pattern of susceptibility/resistance can be attributed to a single genetic locus termed Cmv1 and recently several groups that have been working on the mapping and identification of Cmv1 have met with success. Interestingly, Cmv1 is allelic to a member of the Ly49 gene family, which encode activating or inhibitory transmembrane receptors present on the surface of NK cells. All Ly49 receptors characterized to date interact with MHC class I molecules on potential target cells, resulting in the accumulation of signals to the NK to either 'kill' or 'ignore' the cell based upon the repertoire of MHC class I molecules expressed. The identification of Cmv1 as Ly49H, a stimulatory member of the Ly49 family, adds an interesting twist to the Ly49 story. Although the ligand of Ly49H is not yet known, there is already compelling evidence that the ligand is upregulated on virally infected cells, resulting in specific activation of Ly49H-expressing NK cells. This review provides an historical perspective of the MCMV infection model from its inception to the discovery of the gene responsible for the phenotype and provides a basis for further experiments aimed at understanding the role of NK cells, in general, and Ly49H, in particular, in mediating resistance to cytomegalovirus.