Infections in transplant patients

Microbiological and Molecular Study of Paranasal Sinus Infections of Children with Malignancy and Unknown Origin Fever in Markazi Province, Iran

Background

Children with malignancies are vulnerable to various infections, including sinus infections. Sinusitis is primarily caused by bacterial infections, followed by fungal infections. Due to this, evaluating the occurrence, diversity, and antibiotic susceptibility patterns of bacterial species that cause paranasal sinus infections in children with malignancy and unexplained fever is important.

Objective

To investigate the bacterial species accountable for sinusitis in children with malignancy and unexplained fever, and determine their susceptibility to antibiotics.

Methods

The study involved collecting 90 sinus samples from children aged 5 to 15 years with malignancy in Arak City, Iran. The isolates were identified using a combination of phenotypic, biochemical, and molecular techniques, including specific polymerase chain reaction and 16S ribosomal RNA gene sequencing. Drug susceptibility testing was performed following the Clinical & Laboratory Standards Institute 2021 guidelines.

Results

A total of 36 isolates (40%) were obtained, including 4 isolates of Nocardia (11.12%), 4 isolates of Escherichia coli (11.12%), 3 isolates of Klebsiella pneumoniae (8.33%), 5 isolates of Pseudomonas aeruginosa (13.88%), 3 isolates of Acinetobacter baumannii (8.33%), 4 isolates of Staphylococcus aureus (11.12%), 3 isolates of Staphylococcus epidermidis (8.33%), 5 isolates of Streptococcus agalactiae (13.88%), 2 isolates of Streptococcus pneumoniae (5.55%), and 3 isolates of Enterococcus faecium (8.33%). The isolates showed the most sensitivity to imipenem and trimethoprim-sulfamethoxazole and the least sensitivity to erythromycin and tetracycline.

Conclusions

The findings of the study indicate that sinusitis can contribute to fever of unknown origin in patients with cancer. Therefore, it is recommended to use a combination of molecular and phenotypic methods for accurate identification of isolates. This approach can provide more reliable and precise results, leading to better diagnosis and treatment of sinusitis infections in children with malignancy.

Photodynamic Antimicrobial Activity of a Novel 5,10,15,20-Tetrakis (4-Ethylphenyl) Porphyrin against Clinically Important Bacteria

The growing emergence of microbes resistant to commercially available antibiotic therapies poses a threat to healthcare systems worldwide. Multiple factors have been associated with the increasing incidence of hospital-acquired infections caused by antibiotic-resistant pathogens, including the indiscriminate use of broad-spectrum antibiotics, the massive application of antibiotics in hospitals as a prophylactic measure, self-medication, and nonadherence to pharmacological therapies by patients. In this study, we developed a novel treatment to mitigate the impact of microbial resistance. We synthesized a benzoporphyrin derivative, 5,10,15,20-tetrakis (4-ethylphenyl) porphyrin (TEtPP), with a reaction yield close to 50%. TEtPP exhibited excellent photophysical properties (Φf = 0.12 ± 0.04 and ΦΔ = 0.81 ± 0.23) and was thereby assessed as a potential agent for antibacterial photodynamic therapy. The photophysical properties of the synthesized porphyrin derivative were correlated with the assayed antimicrobial activity. TEtPP showed higher activity against the MRSA strain under irradiation than in the absence of irradiation (minimum inhibitory concentration (MIC) = 69.42 µg/mL vs. MIC = 109.30 µg/mL, p < 0.0001). Similar behavior was observed against P. aeruginosa (irradiated MIC = 54.71 µg/mL vs. nonirradiated MIC = 402.90 µg/mL, p < 0.0001). TEtPP exhibited high activity against S. aureus in both the irradiated and nonirradiated assays (MIC = 67.68 µg/mL vs. MIC = 58.26 µg/mL, p = 0.87).

Low Circulating Concentrations of Very Long Chain Saturated Fatty Acids Are Associated with High Risk of Mortality in Kidney Transplant Recipients

Kidney transplant recipients (KTR) are at increased risk of mortality, particularly from infectious diseases, due to lifelong immunosuppression. Although very long chain saturated fatty acids (VLSFA) have been identified as crucial for phagocytosis and clearance of infections, their association with mortality in immunocompromised patient groups has not been studied. In this prospective cohort study we included 680 outpatient KTR with a functional graft ≥1 year and 193 healthy controls. Plasma VLSFA (arachidonic acid (C20:0), behenic acid (C22:0) and lignoceric acid (C24:0)) were measured by gas chromatography coupled with a flame ionization detector. Cox regression analyses was used to prospectively study the associations of VLSFA with all-cause and cause-specific mortality. All studied VLSFA were significantly lower in KTR compared to healthy controls (all p < 0.001). During a median (interquartile range) follow-up of 5.6 (5.2-6.3) years, 146 (21%) KTR died, of which 41 (28%) died due to infectious diseases. In KTR, C22:0 was inversely associated with risk of all-cause mortality, with a HR (95% CI) per 1-SD-increment of 0.79 (0.64-0.99), independent of adjustment for potential confounders. All studied VLSFA were particularly strongly associated with mortality from infectious causes, with respective HRs for C20:0, C22:0 and C24:0 of 0.53 (0.35-0.82), 0.48 (0.30-0.75), and 0.51 (0.33-0.80), independent of potential confounders. VLSFA are inversely associated with infectious disease mortality in KTR after adjustment, including HDL-cholesterol. Further studies are needed to assess the effect of VLSFA-containing foods on the risk of infectious diseases in immunocompromised patient groups.

Leukocyte transcriptome indicators of development of infection in kidney transplant recipients

After kidney transplantation, infection and death are important clinical complications, especially for the growing numbers of older patients with limited resilience to withstand adverse events. Evaluation of changes in gene expression in immune cells can reveal the underlying mechanisms behind vulnerability to infection. A cohort of 60 kidney transplant recipients was evaluated. Gene expression in peripheral blood mononuclear cells 3 months after kidney transplantation was analyzed to compare differences between patients with infection and those who were infection-free in the first-year post-transplant. Pro-inflammatory genes such as IL1B, CCL4, and TNF were found to be downregulated in post-transplant PBMC from patients who developed infection. In contrast, genes involved in metabolism, HLA genes, and transcripts involved in type I interferon innate antiviral responses were found to be upregulated. Promoter-based bioinformatic analyses implicated increased activity of interferon regulatory factors, erythroid nuclear factor (E2), and CCAAT-enhancer-binding protein (C/EBP) in patients who developed infections. Differential patterns of gene expression were observed in patients who developed infection after kidney transplantation, with patterns distinct from changes associated with patient age, suggesting possible mechanisms behind vulnerability to infection. Assessment of gene expression in blood may offer an approach for patient risk stratification and monitoring after transplantation.

Approach to Transplant Infectious Diseases in the Emergency Department

The emergency department (ED) is an increasingly important site of care for patients who have undergone solid organ transplantation or hematopoietic cell transplantation. It is paramount for emergency physicians to recognize infections early on, obtain appropriate diagnostic testing, initiate empirical antimicrobial therapy, and consider specialty consultation and inpatient admission when caring for these patients. This review provides emergency physicians with an approach to the assessment of transplant patients' underlying risk for infection, formulation of a broad differential diagnosis, and initial management of transplant infectious disease emergencies in the ED.

Increased T cell immunosenescence and accelerated maturation phenotypes in older kidney transplant recipients

Older kidney transplant recipients experience increased rates of infection and death, and less rejection, compared with younger patients. However, little is known about immune dysfunction in older compared with younger kidney transplant recipients and whether it is associated with infection. We evaluated T cell phenotypes including maturation, immune senescence, and exhaustion in a novel investigation into differences in older compared with younger patients receiving identical immune suppression regimens. We evaluated PBMC from 60 kidney transplant recipients (23 older and 37 matched younger patients) by multiparameter immune phenotyping. Older kidney transplant recipients demonstrated decreased frequency of naïve CD4+ and CD8+ T cells, and increased frequency of terminally differentiated, immune senescent, and NK T cells expressing KLRG1. There was a trend towards increased frequency of T cell immune senescence in patients experiencing infection in the first year after transplantation, which reached statistical significance in a multivariate analysis. This pilot study reveals immune dysfunction in older compared with younger transplant recipients, and suggests a likely mechanism for increased vulnerability to infection. The ability to assess T cell maturation and immune senescence in transplant recipients offers the potential for risk stratification and customization of immune suppression to prevent infection and rejection after transplantation.

Primary Care of the Solid Organ Transplant Recipient

Solid organ transplantation (SOT) is one of the major advances in medicine. Care of the SOT recipient is complex and continued partnership with the transplant specialist is essential to manage and treat complications and maintain health. The increased longevity of SOT recipients will lead to their being an evolving part of primary care practice, with ever more opportunities for care, education, and research of this rewarding patient population. This review discusses the overall primary care management of adult SOT recipients.

[Antibiotic resistance: A global crisis]

The introduction of antibiotics into clinical practice represented one of the most important interventions for the control of infectious diseases. Antibiotics have saved millions of lives and have also brought a revolution in medicine. However, an increasing threat has deteriorated the effectiveness of these drugs, that of bacterial resistance to antibiotics, which is defined here as the ability of bacteria to survive in antibiotic concentrations that inhibit/kill others of the same species. In this review some recent and important examples of resistance in pathogens of concern for mankind are mentioned. It is explained, according to present knowledge, the process that led to the current situation in a short time, evolutionarily speaking. It begins with the resistance genes, continues with clones and genetic elements involved in the maintenance and dissemination, and ends with other factors that contribute to its spread. Possible responses to the problem are also reviewed, with special reference to the development of new antibiotics.

MRSA and VRE colonization in solid organ transplantation: a meta-analysis of published studies

The burden of methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococcus (VRE) colonization among the increasing number of solid organ transplant patients has not been systematically explored. We searched PubMed and EMBASE for pertinent articles, performed a meta-analysis of prevalence across eligible studies and estimated the risk of ensuing MRSA or VRE infections relative to colonization status. We stratified effects in the pretransplant and posttransplant period. Twenty-three studies were considered eligible. Seventeen out of 23 (74%) referred to liver transplants. Before transplantation, the pooled prevalence estimate for MRSA and VRE was 8.5% (95% confidence interval [CI] 3.2–15.8) and 11.9% (95% CI 6.8–18.2), respectively. MRSA estimate was influenced by small studies and was lower (4.0%; 95% CI 0.4–10.2) across large studies (>200 patients). After transplantation, the prevalence estimates were 9.4% (95% CI 3.0–18.5) for MRSA and 16.2% (95% CI 10.7–22.6) for VRE. Pretransplant as well as posttransplant MRSA colonization significantly increased the risk for MRSA infections (pooled risk ratio [RR] 5.51; 95% CI 2.36–12.90 and RR 10.56; 95% CI 5.58–19.95, respectively). Pretransplant and posttransplant VRE colonization were also associated with significant risk of VRE infection (RR 6.65; 95% CI 2.54–17.41 and RR 7.93; 95% CI 2.36–26.67, respectively). Solid organ transplantation is a high-risk setting for MRSA and VRE colonization, and carrier state is associated with infection. Upgraded focus in prevention and eradication strategies is warranted.