Bacterial Pathogens Isolated in Liver Transplant Recipients With Surgical Site Infection and Antibiotic Treatment

Low rate of surgical site infections after liver transplantation: A 5-year retrospective cohort study

BACKGROUND

Surgical site infection (SSI) after liver transplant (LT) is common, but no studies have been conducted in Australia. The purpose of this study was to determine the proportion of patients who developed an SSI post-LT in Australia's largest LT unit.

METHODS

This was a single-center retrospective cohort study. We included all LT recipients who were aged 18 years or more and received their transplant between March 1, 2018 and April 1, 2023. The primary outcome was to determine the proportion of LT recipients who developed an SSI within 30 days of transplantation.

RESULTS

There were 404 LTs performed during the study period, and 375 met inclusion criteria. Of these, 8% (n = 31/375) developed an SSI and were classified as superficial (3%, n = 12/375) or deep/organ space (5%, n = 19/375). The most common antibiotics used for prophylaxis were amoxicillin/clavulanate (75%, n = 281/375), followed by piperacillin/tazobactam (17%, n = 62/375). Independent risk factors associated with the development of SSI were Roux-en-Y hepaticojejunostomy (aOR 3.16, 95% CI 1.17-8.28, p = .02), operative time (per 60-min increment) (aOR 1.23, 95% CI 1.02-1.48), and re-operation (aOR 4.16, 95% CI 1.81-9.58, p < .01). Type of antibiotic received perioperatively was not significantly associated with SSI.

CONCLUSION

SSI occurred in 8% of LT recipients and was predominantly related to operation-related factors rather than patient- or antibiotic-related factors.

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

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

Epidemiology of surgical site infections after solid organ transplants in the period 2015-2019: A single-center retrospective cohort study

Surgical site infections (SSI) are severe complications of solid organ transplant (SOT). This retrospective study assessed the epidemiology of and outcomes associated with invasive primary SSI (IP-SSI) occurring within 3 months of transplantation in adult SOT recipients at Duke University over a 5-year period (2015-2019). Among 2073 consecutive SOT recipients, 198 IP-SSI were identified. The IP-SSI rate declined over the period (14.4% in 2015 vs. 8.3% in 2019) and was higher among multi-organ compared with single-organ transplants (33.9% vs. 8.1%, p < .01). SOT recipients with IP-SSI had longer hospital stays than patients without SSI (30.0 vs. 17.0 days, p < .01). Transplant hospitalization (9.6% vs. 2.2%, p < .01), 6-month (11.6% vs. 3.3%, p < .01), and 1-year mortality (15.7% vs. 5.8%, p < .01) were higher in SOT recipients with IP-SSI than in those without. While Gram-positive bacteria were the most common pathogens, urogenital Mollicute and atypical Mycobacteria were identified as an unexpected cause of IP-SSI, particularly among lung transplant recipients. The median time to IP-SSI was 24.0 (IQR 13.8-48.3) days, although the time to IP-SSI varied based on organ transplanted and the causative pathogen. IP-SSI is an important and potentially modifiable complication of SOT, associated with prolonged hospitalizations and reduced survival, particularly in the lung transplant population.

Chronic Wound Infection Model of Acinetobacter baumannii in Outbred Mice

INTRODUCTION

We established a murine wound infection model with doxycycline treatment against multidrug-resistant Acinetobacter baumannii (AB5075) in Institute of Cancer Research (ICR) outbred mice.

METHODS

Using three groups of neutropenic ICR mice, two full-thickness dorsal dermal wounds (6 mm diameter) were made on each mouse. In two groups, wounds were inoculated with 7.0 × 104 colony-forming units of AB5075. Of these two groups, one received a 6-day regimen of doxycycline while the other was sham treated with phosphate-buffered saline as placebo control. Another uninfected/untreated group served as a control. Wound closure, clinical symptoms, bacterial burden in wound beds and organs, and wound histology were investigated.

RESULTS

Doxycycline-treated wounds completely healed by day 21, but untreated, infected wounds failed to heal. Compared to controls, wound infections without treatment resulted in significant reductions in body weight and higher bacterial loads in wound beds, lung, liver, and spleen by day 7. Histological evaluation of wounds on day 21 revealed ulcerated epidermis, muscle necrosis, and bacterial presence in untreated wounds, while wounds treated with doxycycline presented intact epidermis.

CONCLUSIONS

Compared to the previously developed BALB/c dermal wound model, this study demonstrates that the mouse strain selected impacts wound severity and resolution. Furthermore, this mouse model accommodates two dorsal wounds rather than only one. These variations offer investigators increased versatility when designing future studies of wound infection. In conclusion, ICR mice are a viable option as a model of dermal wound infection. They accommodate two simultaneous dorsal wounds, and upon infection, these wounds follow a different pattern of resolution compared to BALB/c mice.

Eliminated routine postorthotopic liver transplant antibiotics in uncomplicated patients leads to equivalent safety outcomes

Objective:

The purpose of this retrospective study was to evaluate safety and efficacy end points of a postoperative antibiotic prophylaxis protocol in liver transplant (LT) patients, which was revised to limit antibiotic use.

Methods:

In the routine antibiotics group (RA), patients routinely received prophylactic antibiotics for around 3 days postoperatively for a variety of rationales, versus the limited antibiotics group (LA), in which patients received antibiotics for the treatment of secondary peritonitis. Patients were included if they were 18 or older and underwent liver transplant between January 2016 and September 2019. In total, 216 patients remained after exclusion: 118 patients in the RA group and 98 patients in the LA group.

Results:

We detected a significant difference in the primary end point of postoperative antibiotic days of therapy. The median days of therapy was 2 for the RA group and 0 for the LA group (P < 0.005). Significantly fewer patients received only intraoperative antibiotics in the RA group versus the LA group: 42 (35.6%) versus 76 (73.5%) respectively (P < .005). There was no significant difference in secondary or safety outcomes, including surgical site infections.

Conclusions:

This study provides evidence that limiting the duration of prophylactic antibiotics postoperatively and treating most patients with only intraoperative antibiotics is safe.

Standardization of post-operative antimicrobials reduced exposure while maintaining good outcomes in pediatric liver transplant recipients

Infections following orthotopic liver transplant (OLT) result in significant morbidity and mortality, warranting careful consideration of risks associated with antibiotic overuse and benefits of infection prevention. In the absence of specific guidelines for antimicrobial prophylaxis in pediatric OLT, we developed a standardized approach to post-operative (post-op) antimicrobial therapy including 48 hours of antibiotics, no vancomycin for post-op fever within the first 48 hours, and caspofungin only for certain situations. The goal was to reduce antimicrobial utilization and adverse outcomes associated with longer duration of and broader treatment while maintaining good outcomes. The impact of this standardization on antimicrobial utilization and clinical outcomes at the largest pediatric liver transplant center in the United States is described. All individuals receiving an OLT from 1/1/17-9/30/17 (N = 38) and 3/14/18-12/13/18 (N = 27) were included in the pre-intervention (PreI) and post-intervention (PostI) groups, respectively. The intervention resulted in a significant reduction in individuals receiving post-op broad-spectrum gram-negative antibiotics for >48 hours (76% PreI vs 44% PostI OLT recipients, P = .01) and post-op vancomycin use (50% PreI, vs 7.4% PostI, P < .001). There were no statistically significant differences between groups for post-op fever, positive pre-/post-operative cultures, receipt of massive transfusion, or hospital length of stay. In conclusion, following the implementation of a standardized approach to post-op prophylaxis, antimicrobial exposure was significantly reduced without affecting OLT recipient outcomes.

Surgical site infection and risk factors following right lobe living donor liver transplantation in adults: A single-center prospective cohort study

INTRODUCTION

Surgical site infection (SSI) is an important cause of decreased graft survival, prolonged hospital stay, and higher costs following living donor liver transplantation. There are several risk factors for SSI. In this cohort study, we aimed to investigate the incidence of SSI at our center and the associated risk factors.

MATERIALS AND METHODS

Adult right lobe living donor liver transplantations were included in this prospective cohort. Patients who died postoperatively within 3 days; patients with infected ascites or open abdomen, cadaveric, or pediatric transplants; and patients with biologic or cryopreserved vascular grafts were excluded. Patients' demographic characteristics and perioperative surgical findings were recorded. SSI follow-up was continued for 90 days. CDC-2017 criteria were used to diagnose SSI. In the presence of superficial, deep, and organ/space SSI, only the organ in the poorest condition was included in SSI evaluation. The patients were administered similar to antibiotic prophylaxes and immunosuppressive protocols.

RESULTS

A total of 101 patients were enrolled in this study, of which 30 (29.7%) were diagnosed with SSI. Organ/space, only deep, and only superficial SSI were noted in 90% (27/30), 6.7% (2/30), and 3.3% (1/30) of the patients, respectively. Twenty-five of 30 patients with SSI had a remote site infection. One or more bacteria observed in cultures were obtained from 28 patients. A donor-recipient age difference of >10 years, cold ischemia lasting for ≥150 minutes, surgical duration of ≥600 minutes, intraoperative hemorrhage of ≥1000 mL, intraoperative blood transfusion, biliary leak or stricture, prolonged mechanical ventilation, prolonged intensive care unit and hospital stay, remote site infection, and the need for reoperation were associated with increased SSI incidence. Preoperative and intraoperative levels of blood glucose, albumin, and hemoglobin were not associated with SSI. A donor-recipient age difference of >10 years, remote site infection, and biliary leak were found to be independent risk factors for SSI. Hospital mortality with and without SSIs was 6.7% vs 4.4%, P = .61.

DISCUSSION

Organ/space SSIs were the essential part of SSIs following right lobe living donor liver transplantations. Donor-recipient age gap, prolonged cold ischemia time, complicated surgery, and postoperative biliary complications were the main causes of SSIs. Although they did not increase the perioperative mortality, they promote increased rate of reoperations, remote infections, prolonged intensive care unit, and hospital stays.

Intraoperative Versus Extended Antibiotic Prophylaxis in Liver Transplant Surgery: A Randomized Controlled Pilot Trial

The appropriate duration of surgical antibiotic prophylaxis in orthotopic liver transplantation (OLT) in the presence of significant iatrogenic immunosuppression is unclear. We hypothesized that 72 hours of perioperative antibiotic prophylaxis would decrease rates of surgical site infection (SSI) in OLT patients when compared with intraoperative antibiotic prophylaxis alone. OLT recipients were randomized to receive either intraoperative antibiotics only (short antibiotics [SAs]) or 72 hours of perioperative antibiotics (extended antibiotics [EAs]). A total of 102 patients were randomized: 51 to the EA group and 51 to the SA group. Rates of SSI and nosocomial infection (NI) in the SA group were 19% and 17%, respectively, compared with 27% (SSI; P = 0.36) and 22% (NI; P = 0.47) in the EA group, although these differences were not statistically significant. Intensive care unit (ICU) length of stay (LOS), hospital LOS, 30-day mortality, and time to infection were also similar between the 2 groups. Patients developing infections had longer ICU LOS and hospital LOS and a higher association with reoperation, endoscopic retrograde cholangiopancreatography, and 30-day readmission. In conclusion, extending perioperative antibiotics to 72 hours from intraoperative dosing alone in OLT patients does not appear to decrease the incidence of SSI or NI. The results from this pilot trial with 60% power suggest that it is acceptable for OLT recipients to receive intraoperative antibiotic prophylaxis alone.