Utility of Urine Cultures During Febrile Neutropenia Workup in Hematopoietic Stem Cell Transplantation Recipients Without Urinary Symptoms

The utility of obtaining screening urine cultures for febrile neutropenia (FN) during hematopoietic stem cell transplant (HCT) is unknown. In 667 adult HCT patients with FN, only 40 (6%) were found with bacteriuria. Antibiotics were modified in 3 patients (0.4%) based on urine cultures and none developed urinary-associated infectious complications.

Walk before you run: Feasibility challenges and lessons learned from the PROCLAIM study, a multicenter randomized controlled trial of misoprostol for prevention of recurrent Clostridioides difficile during COVID-19

We analyzed our challenging experience with a randomized controlled trial of misoprostol for prevention of recurrent C. difficile. Despite careful prescreening and thoughtful protocol modifications to facilitate enrollment, we closed the study early after enrolling just 7 participants over 3 years. We share lessons learned, noting the importance of feasibility studies, inclusion of biomarker outcomes, and dissemination of such findings to inform future research design and implementation successes.

Multidrug-Resistant Gram-Negative Bacteria in Burn Patients

Patients with burn injuries are at high risk for infectious complications, and infections are the most common cause of death after the first 72 h of hospitalization. Hospital-acquired infections caused by multidrug resistant (MDR) Gram-negative bacteria (GNB) in this population are concerning. Here, we evaluated carriage with MDR GNB in patients in a large tertiary-care burn intensive care unit. Twenty-nine patients in the burn unit were screened for intestinal carriage. Samples were cultured on selective media. Median time from admission to the burn unit to first sample collection was 9 days (IQR 5 - 17 days). In 21 (72%) patients, MDR GNB were recovered; the most common bacterial species isolated was Pseudomonas aeruginosa, which was found in 11/29 (38%) of patients. Two of these patients later developed bloodstream infections with P. aeruginosa. Transmission of KPC-31-producing ST22 Citrobacter freundii was detected. Samples from two patients grew genetically similar C. freundii isolates that were resistant to ceftazidime-avibactam. On analysis of whole-genome sequencing, blaKPC-31 was part of a Tn4401b transposon that was present on two different plasmids in each C. freundii isolate. Plasmid curing experiments showed that removal of both copies of blaKPC-31 was required to restore susceptibility to ceftazidime-avibactam. In summary, MDR GNB colonization is common in burn patients and patient-to-patient transmission of highly resistant GNB occurs. These results emphasize the ongoing need for infection prevention and antimicrobial stewardship efforts in this highly vulnerable population.

An overview of COVID-19 in solid organ transplantation

BACKGROUND

The COVID-19 pandemic has influenced the field of solid organ transplantation (SOT) in many ways. COVID-19 has led to programmatic impacts and changes in donor and recipient selection. Several studies have evaluated the course, optimal treatment, and prevention of COVID-19 in SOT recipients.

OBJECTIVES

To review the literature on COVID-19 in SOT recipients.

SOURCES

PubMed, Web of Science, and Google Scholar were searched. The search was restricted to articles published between January 1, 2019 and December 1, 2021.

CONTENT

The COVID-19 pandemic initially led to a decreased volume of solid organ transplants. However, transplant volumes at most centres have rebounded. Donor selection remains an incompletely defined issue. Several reports suggest that donor-derived SARS-CoV-2 infections occur only in lung transplant recipients and that other organs from SARS-CoV-2 PCR-positive donors could potentially be safely used. However, these data are limited to case series. Transplantation for end-stage lung disease after COVID-19 infection is increasingly common and has been performed with acceptable outcomes. In acute COVID-19 in a transplant candidate, transplantation should be delayed when feasible. After adjustment, mortality after COVID-19 appear similar in SOT recipients compared to the general population, with notable increased use of antiviral and anti-inflammatory treatment options. Prevention of COVID-19 is key in SOT recipients. Vaccination of SOT recipients and anyone who is in contact with SOT recipients is one of the cornerstones of prevention. Nonpharmacological interventions such as face coverings, hand hygiene, and physical distancing remain ever important as well.

IMPLICATIONS

The COVID-19 pandemic continues to have an important impact on SOT candidates and recipients. Prevention of infection is the most important measure and requires careful attention to approaches to vaccination and messaging of the ongoing need for face coverings, physical distancing, and hand hygiene.

SARS-CoV-2 D614G variant exhibits efficient replication ex vivo and transmission in vivo

The spike aspartic acid-614 to glycine (D614G) substitution is prevalent in global severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) strains, but its effects on viral pathogenesis and transmissibility remain unclear. We engineered a SARS-CoV-2 variant containing this substitution. The variant exhibits more efficient infection, replication, and competitive fitness in primary human airway epithelial cells but maintains similar morphology and in vitro neutralization properties, compared with the ancestral wild-type virus. Infection of human angiotensin-converting enzyme 2 (ACE2) transgenic mice and Syrian hamsters with both viruses resulted in similar viral titers in respiratory tissues and pulmonary disease. However, the D614G variant transmits significantly faster and displayed increased competitive fitness than the wild-type virus in hamsters. These data show that the D614G substitution enhances SARS-CoV-2 infectivity, competitive fitness, and transmission in primary human cells and animal models.

Convalescent Plasma Therapy in Four Critically Ill Pediatric Patients With Coronavirus Disease 2019: A Case Series

Coronavirus disease 2019 is a pandemic with no specific therapeutic agents or vaccination. Small published case series on critically ill adults suggest improvements in clinical status with minimal adverse events when patients receive coronavirus disease 2019 convalescent plasma, but data on critically ill pediatric patients are lacking. We report a series of four critically ill pediatric patients with acute respiratory failure who received coronavirus disease 2019 convalescent plasma as a treatment strategy for severe disease.

CASE SUMMARY

Patients ranged in age from 5 to 16 years old. All patients received coronavirus disease 2019 convalescent plasma within the first 26 hours of hospitalization. Additional disease modifying agents were also used. All patients made a full recovery and were discharged home off of oxygen support. No adverse events occurred from the coronavirus disease 2019 convalescent plasma transfusions.

CONCLUSION

Coronavirus disease 2019 convalescent plasma is a feasible therapy for critically ill pediatric patients infected with severe acute respiratory syndrome coronavirus 2. Well-designed clinical trials are necessary to determine overall safety and efficacy of coronavirus disease 2019 convalescent plasma and additional treatment modalities in pediatric patients.

SARS-CoV-2 Reverse Genetics Reveals a Variable Infection Gradient in the Respiratory Tract

The mode of acquisition and causes for the variable clinical spectrum of coronavirus disease 2019 (COVID-19) remain unknown. We utilized a reverse genetics system to generate a GFP reporter virus to explore severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pathogenesis and a luciferase reporter virus to demonstrate sera collected from SARS and COVID-19 patients exhibited limited cross-CoV neutralization. High-sensitivity RNA in situ mapping revealed the highest angiotensin-converting enzyme 2 (ACE2) expression in the nose with decreasing expression throughout the lower respiratory tract, paralleled by a striking gradient of SARS-CoV-2 infection in proximal (high) versus distal (low) pulmonary epithelial cultures. COVID-19 autopsied lung studies identified focal disease and, congruent with culture data, SARS-CoV-2-infected ciliated and type 2 pneumocyte cells in airway and alveolar regions, respectively. These findings highlight the nasal susceptibility to SARS-CoV-2 with likely subsequent aspiration-mediated virus seeding to the lung in SARS-CoV-2 pathogenesis. These reagents provide a foundation for investigations into virus-host interactions in protective immunity, host susceptibility, and virus pathogenesis.

SARS-CoV-2 Reverse Genetics Reveals a Variable Infection Gradient in the Respiratory Tract

The mode of acquisition and causes for the variable clinical spectrum of coronavirus disease 2019 (COVID-19) remain unknown. We utilized a reverse genetics system to generate a GFP reporter virus to explore severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pathogenesis and a luciferase reporter virus to demonstrate sera collected from SARS and COVID-19 patients exhibited limited cross-CoV neutralization. High-sensitivity RNA in situ mapping revealed the highest angiotensin-converting enzyme 2 (ACE2) expression in the nose with decreasing expression throughout the lower respiratory tract, paralleled by a striking gradient of SARS-CoV-2 infection in proximal (high) versus distal (low) pulmonary epithelial cultures. COVID-19 autopsied lung studies identified focal disease and, congruent with culture data, SARS-CoV-2-infected ciliated and type 2 pneumocyte cells in airway and alveolar regions, respectively. These findings highlight the nasal susceptibility to SARS-CoV-2 with likely subsequent aspiration-mediated virus seeding to the lung in SARS-CoV-2 pathogenesis. These reagents provide a foundation for investigations into virus-host interactions in protective immunity, host susceptibility, and virus pathogenesis.

The receptor binding domain of the viral spike protein is an immunodominant and highly specific target of antibodies in SARS-CoV-2 patients

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that first emerged in late 2019 is responsible for a pandemic of severe respiratory illness. People infected with this highly contagious virus can present with clinically inapparent, mild, or severe disease. Currently, the virus infection in individuals and at the population level is being monitored by PCR testing of symptomatic patients for the presence of viral RNA. There is an urgent need for SARS-CoV-2 serologic tests to identify all infected individuals, irrespective of clinical symptoms, to conduct surveillance and implement strategies to contain spread. As the receptor binding domain (RBD) of the spike protein is poorly conserved between SARS-CoVs and other pathogenic human coronaviruses, the RBD represents a promising antigen for detecting CoV-specific antibodies in people. Here we use a large panel of human sera (63 SARS-CoV-2 patients and 71 control subjects) and hyperimmune sera from animals exposed to zoonotic CoVs to evaluate RBD's performance as an antigen for reliable detection of SARS-CoV-2-specific antibodies. By day 9 after the onset of symptoms, the recombinant SARS-CoV-2 RBD antigen was highly sensitive (98%) and specific (100%) for antibodies induced by SARS-CoVs. We observed a strong correlation between levels of RBD binding antibodies and SARS-CoV-2 neutralizing antibodies in patients. Our results, which reveal the early kinetics of SARS-CoV-2 antibody responses, support using the RBD antigen in serological diagnostic assays and RBD-specific antibody levels as a correlate of SARS-CoV-2 neutralizing antibodies in people.

The RBD Of The Spike Protein Of SARS-Group Coronaviruses Is A Highly Specific Target Of SARS-CoV-2 Antibodies But Not Other Pathogenic Human and Animal Coronavirus Antibodies

A new Severe Acute Respiratory Syndrome Coronavirus variant (SARS-CoV-2) that first emerged in late 2019 is responsible for a pandemic of severe respiratory illness. People infected with this highly contagious virus present with clinically inapparent, mild or severe disease. Currently, the presence of the virus in individual patients and at the population level is being monitored by testing symptomatic cases by PCR for the presence of viral RNA. There is an urgent need for SARS-CoV-2 serologic tests to identify all infected individuals, irrespective of clinical symptoms, to conduct surveillance and implement strategies to contain spread. As the receptor binding domain (RBD) of the viral spike (S) protein is poorly conserved between SARS-CoVs and other pathogenic human coronaviruses, the RBD represents a promising antigen for detecting CoV specific antibodies in people. Here we use a large panel of human sera (70 SARS-CoV-2 patients and 71 control subjects) and hyperimmune sera from animals exposed to zoonotic CoVs to evaluate the performance of the RBD as an antigen for accurate detection of SARS-CoV-2-specific antibodies. By day 9 after the onset of symptoms, the recombinant SARS-CoV-2 RBD antigen was highly sensitive (98%) and specific (100%) to antibodies induced by SARS-CoVs. We observed a robust correlation between levels of RBD binding antibodies and SARS-CoV-2 neutralizing antibodies in patients. Our results, which reveal the early kinetics of SARS-CoV-2 antibody responses, strongly support the use of RBD-based antibody assays for population-level surveillance and as a correlate of neutralizing antibody levels in people who have recovered from SARS-CoV-2 infections.

730. Cefiderocol for the Treatment of Achromobacter xylosoxidans Infections in Two Lung Transplant Patients with Cystic Fibrosis

Background

Achromobacter xylosoxidansis a highly resistant Gram-negative bacterium that causes chronic infections in patients with cystic fibrosis (CF). Treatment options for A. xylosoxidans are limited. In the peri-lung transplant setting, the treatment of A. xylosoxidans infections is especially challenging. Cefiderocol is a novel siderophore cephalosporin antibiotic with broad anti-Gram-negative activity, including against A. xylosoxidans. We report here two cases of compassionate use of cefiderocol in CF lung transplant recipients with A. xylosoxidans infection.

Methods

Cefiderocol was obtained through compassionate use from its manufacturer, with approval from the local Institutional Review Board. In the first case, it was used as salvage treatment, and in the second case as a planned part of the peri-transplant regimen.

Results

A male in his 20s with CF and a trimethoprim-sulfamethoxazole (TMP-SMX) allergy was chronically colonized by A. xylosoxidans, which was sensitive only to piperacillin–tazobactam (PIP-TAZ), and TMP-SMX. After lung transplant, he developed A. xylosoxidansbacteremia, and extended-infusion PIP-TAZ was started. Repeat bronchoscopy grew A. xylosoxidans. Due to lack of improvement, cefiderocol was added to PIP-TAZ with rapid clinical improvement. However, after completing his course, he was readmitted with A. xylosoxidans pneumonia. He was treated with 6 weeks of cefiderocol and imipenem and has been well since with an 8-month follow-up. In the second case, cefiderocol was used as part of the planned peri-transplant regimen for a female with CF in her late teens, with chronic A. xylosoxidans colonization, which was intermediate to PIP-TAZ, and resistant to all other drugs tested. Her native lungs grew 4+ A. xylosoxidans at the time of explant. Post-transplant, she was treated with 5 weeks of meropenem and 6 weeks of cefiderocol. At four-month follow-up, she is doing well. However, she is asymptomatically colonized with A. xylosoxidanspost-transplant. Isolates from both cases were susceptible to cefiderocol (case #1 MIC = 0.12; case #2 pretreatment MIC = 1, post-treatment MIC.

Conclusion

Cefiderocol may be a useful option for lung transplant recipients with A. xylosoxidans infections.

Disclosures

Anne Lachiewicz, MD, MPH, MicroGenDx: Consultant; Shionogi: Consultant.

Intestinal parasitic infection alters bone marrow derived dendritic cell inflammatory cytokine production in response to bacterial endotoxin in a diet-dependent manner

Giardia lamblia is a common intestinal parasitic infection that although often acutely asymptomatic, is associated with debilitating chronic intestinal and extra-intestinal sequelae. In previously healthy adults, a primary sporadic Giardia infection can lead to gut dysfunction and fatigue. These symptoms correlate with markers of inflammation that persist well after the infection is cleared. In contrast, in endemic settings, first exposure occurs in children who are frequently malnourished and also co-infected with other enteropathogens. In these children, Giardia rarely causes symptoms and associates with several decreased markers of inflammation. Mechanisms underlying these disparate and potentially enduring outcomes following Giardia infection are not presently well understood. A body of work suggests that the outcome of experimental Giardia infection is influenced by the nutritional status of the host. Here, we explore the consequences of experimental Giardia infection under conditions of protein sufficiency or deficiency on cytokine responses of ex vivo bone marrow derived dendritic cells (BMDCs) to endotoxin stimulation. We show that BMDCs from Giardia- challenged mice on a protein sufficient diet produce more IL-23 when compared to uninfected controls whereas BMDCs from Giardia challenged mice fed a protein deficient diet do not. Further, in vivo co-infection with Giardia attenuates robust IL-23 responses in endotoxin-stimulated BMDCs from protein deficient mice harboring enteroaggregative Escherichia coli. These results suggest that intestinal Giardia infection may have extra-intestinal effects on BMDC inflammatory cytokine production in a diet dependent manner, and that Giardia may influence the severity of the innate immune response to other enteropathogens. This work supports recent findings that intestinal microbial exposure may have lasting influences on systemic inflammatory responses, and may provide better understanding of potential mechanisms of post-infectious sequelae and clinical variation during Giardia and enteropathogen co-infection.